| Index: third_party/sqlite/sqlite-src-3170000/src/btree.c
|
| diff --git a/third_party/sqlite/sqlite-src-3170000/src/btree.c b/third_party/sqlite/sqlite-src-3170000/src/btree.c
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..de553423b8847ff23b58c2ce3ec8218314c7a2e8
|
| --- /dev/null
|
| +++ b/third_party/sqlite/sqlite-src-3170000/src/btree.c
|
| @@ -0,0 +1,9767 @@
|
| +/*
|
| +** 2004 April 6
|
| +**
|
| +** The author disclaims copyright to this source code. In place of
|
| +** a legal notice, here is a blessing:
|
| +**
|
| +** May you do good and not evil.
|
| +** May you find forgiveness for yourself and forgive others.
|
| +** May you share freely, never taking more than you give.
|
| +**
|
| +*************************************************************************
|
| +** This file implements an external (disk-based) database using BTrees.
|
| +** See the header comment on "btreeInt.h" for additional information.
|
| +** Including a description of file format and an overview of operation.
|
| +*/
|
| +#include "btreeInt.h"
|
| +
|
| +/*
|
| +** The header string that appears at the beginning of every
|
| +** SQLite database.
|
| +*/
|
| +static const char zMagicHeader[] = SQLITE_FILE_HEADER;
|
| +
|
| +/*
|
| +** Set this global variable to 1 to enable tracing using the TRACE
|
| +** macro.
|
| +*/
|
| +#if 0
|
| +int sqlite3BtreeTrace=1; /* True to enable tracing */
|
| +# define TRACE(X) if(sqlite3BtreeTrace){printf X;fflush(stdout);}
|
| +#else
|
| +# define TRACE(X)
|
| +#endif
|
| +
|
| +/*
|
| +** Extract a 2-byte big-endian integer from an array of unsigned bytes.
|
| +** But if the value is zero, make it 65536.
|
| +**
|
| +** This routine is used to extract the "offset to cell content area" value
|
| +** from the header of a btree page. If the page size is 65536 and the page
|
| +** is empty, the offset should be 65536, but the 2-byte value stores zero.
|
| +** This routine makes the necessary adjustment to 65536.
|
| +*/
|
| +#define get2byteNotZero(X) (((((int)get2byte(X))-1)&0xffff)+1)
|
| +
|
| +/*
|
| +** Values passed as the 5th argument to allocateBtreePage()
|
| +*/
|
| +#define BTALLOC_ANY 0 /* Allocate any page */
|
| +#define BTALLOC_EXACT 1 /* Allocate exact page if possible */
|
| +#define BTALLOC_LE 2 /* Allocate any page <= the parameter */
|
| +
|
| +/*
|
| +** Macro IfNotOmitAV(x) returns (x) if SQLITE_OMIT_AUTOVACUUM is not
|
| +** defined, or 0 if it is. For example:
|
| +**
|
| +** bIncrVacuum = IfNotOmitAV(pBtShared->incrVacuum);
|
| +*/
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +#define IfNotOmitAV(expr) (expr)
|
| +#else
|
| +#define IfNotOmitAV(expr) 0
|
| +#endif
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +/*
|
| +** A list of BtShared objects that are eligible for participation
|
| +** in shared cache. This variable has file scope during normal builds,
|
| +** but the test harness needs to access it so we make it global for
|
| +** test builds.
|
| +**
|
| +** Access to this variable is protected by SQLITE_MUTEX_STATIC_MASTER.
|
| +*/
|
| +#ifdef SQLITE_TEST
|
| +BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
|
| +#else
|
| +static BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
|
| +#endif
|
| +#endif /* SQLITE_OMIT_SHARED_CACHE */
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +/*
|
| +** Enable or disable the shared pager and schema features.
|
| +**
|
| +** This routine has no effect on existing database connections.
|
| +** The shared cache setting effects only future calls to
|
| +** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
|
| +*/
|
| +int sqlite3_enable_shared_cache(int enable){
|
| + sqlite3GlobalConfig.sharedCacheEnabled = enable;
|
| + return SQLITE_OK;
|
| +}
|
| +#endif
|
| +
|
| +
|
| +
|
| +#ifdef SQLITE_OMIT_SHARED_CACHE
|
| + /*
|
| + ** The functions querySharedCacheTableLock(), setSharedCacheTableLock(),
|
| + ** and clearAllSharedCacheTableLocks()
|
| + ** manipulate entries in the BtShared.pLock linked list used to store
|
| + ** shared-cache table level locks. If the library is compiled with the
|
| + ** shared-cache feature disabled, then there is only ever one user
|
| + ** of each BtShared structure and so this locking is not necessary.
|
| + ** So define the lock related functions as no-ops.
|
| + */
|
| + #define querySharedCacheTableLock(a,b,c) SQLITE_OK
|
| + #define setSharedCacheTableLock(a,b,c) SQLITE_OK
|
| + #define clearAllSharedCacheTableLocks(a)
|
| + #define downgradeAllSharedCacheTableLocks(a)
|
| + #define hasSharedCacheTableLock(a,b,c,d) 1
|
| + #define hasReadConflicts(a, b) 0
|
| +#endif
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| +/*
|
| +**** This function is only used as part of an assert() statement. ***
|
| +**
|
| +** Check to see if pBtree holds the required locks to read or write to the
|
| +** table with root page iRoot. Return 1 if it does and 0 if not.
|
| +**
|
| +** For example, when writing to a table with root-page iRoot via
|
| +** Btree connection pBtree:
|
| +**
|
| +** assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) );
|
| +**
|
| +** When writing to an index that resides in a sharable database, the
|
| +** caller should have first obtained a lock specifying the root page of
|
| +** the corresponding table. This makes things a bit more complicated,
|
| +** as this module treats each table as a separate structure. To determine
|
| +** the table corresponding to the index being written, this
|
| +** function has to search through the database schema.
|
| +**
|
| +** Instead of a lock on the table/index rooted at page iRoot, the caller may
|
| +** hold a write-lock on the schema table (root page 1). This is also
|
| +** acceptable.
|
| +*/
|
| +static int hasSharedCacheTableLock(
|
| + Btree *pBtree, /* Handle that must hold lock */
|
| + Pgno iRoot, /* Root page of b-tree */
|
| + int isIndex, /* True if iRoot is the root of an index b-tree */
|
| + int eLockType /* Required lock type (READ_LOCK or WRITE_LOCK) */
|
| +){
|
| + Schema *pSchema = (Schema *)pBtree->pBt->pSchema;
|
| + Pgno iTab = 0;
|
| + BtLock *pLock;
|
| +
|
| + /* If this database is not shareable, or if the client is reading
|
| + ** and has the read-uncommitted flag set, then no lock is required.
|
| + ** Return true immediately.
|
| + */
|
| + if( (pBtree->sharable==0)
|
| + || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted))
|
| + ){
|
| + return 1;
|
| + }
|
| +
|
| + /* If the client is reading or writing an index and the schema is
|
| + ** not loaded, then it is too difficult to actually check to see if
|
| + ** the correct locks are held. So do not bother - just return true.
|
| + ** This case does not come up very often anyhow.
|
| + */
|
| + if( isIndex && (!pSchema || (pSchema->schemaFlags&DB_SchemaLoaded)==0) ){
|
| + return 1;
|
| + }
|
| +
|
| + /* Figure out the root-page that the lock should be held on. For table
|
| + ** b-trees, this is just the root page of the b-tree being read or
|
| + ** written. For index b-trees, it is the root page of the associated
|
| + ** table. */
|
| + if( isIndex ){
|
| + HashElem *p;
|
| + for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){
|
| + Index *pIdx = (Index *)sqliteHashData(p);
|
| + if( pIdx->tnum==(int)iRoot ){
|
| + if( iTab ){
|
| + /* Two or more indexes share the same root page. There must
|
| + ** be imposter tables. So just return true. The assert is not
|
| + ** useful in that case. */
|
| + return 1;
|
| + }
|
| + iTab = pIdx->pTable->tnum;
|
| + }
|
| + }
|
| + }else{
|
| + iTab = iRoot;
|
| + }
|
| +
|
| + /* Search for the required lock. Either a write-lock on root-page iTab, a
|
| + ** write-lock on the schema table, or (if the client is reading) a
|
| + ** read-lock on iTab will suffice. Return 1 if any of these are found. */
|
| + for(pLock=pBtree->pBt->pLock; pLock; pLock=pLock->pNext){
|
| + if( pLock->pBtree==pBtree
|
| + && (pLock->iTable==iTab || (pLock->eLock==WRITE_LOCK && pLock->iTable==1))
|
| + && pLock->eLock>=eLockType
|
| + ){
|
| + return 1;
|
| + }
|
| + }
|
| +
|
| + /* Failed to find the required lock. */
|
| + return 0;
|
| +}
|
| +#endif /* SQLITE_DEBUG */
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| +/*
|
| +**** This function may be used as part of assert() statements only. ****
|
| +**
|
| +** Return true if it would be illegal for pBtree to write into the
|
| +** table or index rooted at iRoot because other shared connections are
|
| +** simultaneously reading that same table or index.
|
| +**
|
| +** It is illegal for pBtree to write if some other Btree object that
|
| +** shares the same BtShared object is currently reading or writing
|
| +** the iRoot table. Except, if the other Btree object has the
|
| +** read-uncommitted flag set, then it is OK for the other object to
|
| +** have a read cursor.
|
| +**
|
| +** For example, before writing to any part of the table or index
|
| +** rooted at page iRoot, one should call:
|
| +**
|
| +** assert( !hasReadConflicts(pBtree, iRoot) );
|
| +*/
|
| +static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
|
| + BtCursor *p;
|
| + for(p=pBtree->pBt->pCursor; p; p=p->pNext){
|
| + if( p->pgnoRoot==iRoot
|
| + && p->pBtree!=pBtree
|
| + && 0==(p->pBtree->db->flags & SQLITE_ReadUncommitted)
|
| + ){
|
| + return 1;
|
| + }
|
| + }
|
| + return 0;
|
| +}
|
| +#endif /* #ifdef SQLITE_DEBUG */
|
| +
|
| +/*
|
| +** Query to see if Btree handle p may obtain a lock of type eLock
|
| +** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
|
| +** SQLITE_OK if the lock may be obtained (by calling
|
| +** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
|
| +*/
|
| +static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
|
| + BtShared *pBt = p->pBt;
|
| + BtLock *pIter;
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
|
| + assert( p->db!=0 );
|
| + assert( !(p->db->flags&SQLITE_ReadUncommitted)||eLock==WRITE_LOCK||iTab==1 );
|
| +
|
| + /* If requesting a write-lock, then the Btree must have an open write
|
| + ** transaction on this file. And, obviously, for this to be so there
|
| + ** must be an open write transaction on the file itself.
|
| + */
|
| + assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) );
|
| + assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE );
|
| +
|
| + /* This routine is a no-op if the shared-cache is not enabled */
|
| + if( !p->sharable ){
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + /* If some other connection is holding an exclusive lock, the
|
| + ** requested lock may not be obtained.
|
| + */
|
| + if( pBt->pWriter!=p && (pBt->btsFlags & BTS_EXCLUSIVE)!=0 ){
|
| + sqlite3ConnectionBlocked(p->db, pBt->pWriter->db);
|
| + return SQLITE_LOCKED_SHAREDCACHE;
|
| + }
|
| +
|
| + for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
|
| + /* The condition (pIter->eLock!=eLock) in the following if(...)
|
| + ** statement is a simplification of:
|
| + **
|
| + ** (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK)
|
| + **
|
| + ** since we know that if eLock==WRITE_LOCK, then no other connection
|
| + ** may hold a WRITE_LOCK on any table in this file (since there can
|
| + ** only be a single writer).
|
| + */
|
| + assert( pIter->eLock==READ_LOCK || pIter->eLock==WRITE_LOCK );
|
| + assert( eLock==READ_LOCK || pIter->pBtree==p || pIter->eLock==READ_LOCK);
|
| + if( pIter->pBtree!=p && pIter->iTable==iTab && pIter->eLock!=eLock ){
|
| + sqlite3ConnectionBlocked(p->db, pIter->pBtree->db);
|
| + if( eLock==WRITE_LOCK ){
|
| + assert( p==pBt->pWriter );
|
| + pBt->btsFlags |= BTS_PENDING;
|
| + }
|
| + return SQLITE_LOCKED_SHAREDCACHE;
|
| + }
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +#endif /* !SQLITE_OMIT_SHARED_CACHE */
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +/*
|
| +** Add a lock on the table with root-page iTable to the shared-btree used
|
| +** by Btree handle p. Parameter eLock must be either READ_LOCK or
|
| +** WRITE_LOCK.
|
| +**
|
| +** This function assumes the following:
|
| +**
|
| +** (a) The specified Btree object p is connected to a sharable
|
| +** database (one with the BtShared.sharable flag set), and
|
| +**
|
| +** (b) No other Btree objects hold a lock that conflicts
|
| +** with the requested lock (i.e. querySharedCacheTableLock() has
|
| +** already been called and returned SQLITE_OK).
|
| +**
|
| +** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM
|
| +** is returned if a malloc attempt fails.
|
| +*/
|
| +static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
|
| + BtShared *pBt = p->pBt;
|
| + BtLock *pLock = 0;
|
| + BtLock *pIter;
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
|
| + assert( p->db!=0 );
|
| +
|
| + /* A connection with the read-uncommitted flag set will never try to
|
| + ** obtain a read-lock using this function. The only read-lock obtained
|
| + ** by a connection in read-uncommitted mode is on the sqlite_master
|
| + ** table, and that lock is obtained in BtreeBeginTrans(). */
|
| + assert( 0==(p->db->flags&SQLITE_ReadUncommitted) || eLock==WRITE_LOCK );
|
| +
|
| + /* This function should only be called on a sharable b-tree after it
|
| + ** has been determined that no other b-tree holds a conflicting lock. */
|
| + assert( p->sharable );
|
| + assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );
|
| +
|
| + /* First search the list for an existing lock on this table. */
|
| + for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
|
| + if( pIter->iTable==iTable && pIter->pBtree==p ){
|
| + pLock = pIter;
|
| + break;
|
| + }
|
| + }
|
| +
|
| + /* If the above search did not find a BtLock struct associating Btree p
|
| + ** with table iTable, allocate one and link it into the list.
|
| + */
|
| + if( !pLock ){
|
| + pLock = (BtLock *)sqlite3MallocZero(sizeof(BtLock));
|
| + if( !pLock ){
|
| + return SQLITE_NOMEM_BKPT;
|
| + }
|
| + pLock->iTable = iTable;
|
| + pLock->pBtree = p;
|
| + pLock->pNext = pBt->pLock;
|
| + pBt->pLock = pLock;
|
| + }
|
| +
|
| + /* Set the BtLock.eLock variable to the maximum of the current lock
|
| + ** and the requested lock. This means if a write-lock was already held
|
| + ** and a read-lock requested, we don't incorrectly downgrade the lock.
|
| + */
|
| + assert( WRITE_LOCK>READ_LOCK );
|
| + if( eLock>pLock->eLock ){
|
| + pLock->eLock = eLock;
|
| + }
|
| +
|
| + return SQLITE_OK;
|
| +}
|
| +#endif /* !SQLITE_OMIT_SHARED_CACHE */
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +/*
|
| +** Release all the table locks (locks obtained via calls to
|
| +** the setSharedCacheTableLock() procedure) held by Btree object p.
|
| +**
|
| +** This function assumes that Btree p has an open read or write
|
| +** transaction. If it does not, then the BTS_PENDING flag
|
| +** may be incorrectly cleared.
|
| +*/
|
| +static void clearAllSharedCacheTableLocks(Btree *p){
|
| + BtShared *pBt = p->pBt;
|
| + BtLock **ppIter = &pBt->pLock;
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( p->sharable || 0==*ppIter );
|
| + assert( p->inTrans>0 );
|
| +
|
| + while( *ppIter ){
|
| + BtLock *pLock = *ppIter;
|
| + assert( (pBt->btsFlags & BTS_EXCLUSIVE)==0 || pBt->pWriter==pLock->pBtree );
|
| + assert( pLock->pBtree->inTrans>=pLock->eLock );
|
| + if( pLock->pBtree==p ){
|
| + *ppIter = pLock->pNext;
|
| + assert( pLock->iTable!=1 || pLock==&p->lock );
|
| + if( pLock->iTable!=1 ){
|
| + sqlite3_free(pLock);
|
| + }
|
| + }else{
|
| + ppIter = &pLock->pNext;
|
| + }
|
| + }
|
| +
|
| + assert( (pBt->btsFlags & BTS_PENDING)==0 || pBt->pWriter );
|
| + if( pBt->pWriter==p ){
|
| + pBt->pWriter = 0;
|
| + pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING);
|
| + }else if( pBt->nTransaction==2 ){
|
| + /* This function is called when Btree p is concluding its
|
| + ** transaction. If there currently exists a writer, and p is not
|
| + ** that writer, then the number of locks held by connections other
|
| + ** than the writer must be about to drop to zero. In this case
|
| + ** set the BTS_PENDING flag to 0.
|
| + **
|
| + ** If there is not currently a writer, then BTS_PENDING must
|
| + ** be zero already. So this next line is harmless in that case.
|
| + */
|
| + pBt->btsFlags &= ~BTS_PENDING;
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** This function changes all write-locks held by Btree p into read-locks.
|
| +*/
|
| +static void downgradeAllSharedCacheTableLocks(Btree *p){
|
| + BtShared *pBt = p->pBt;
|
| + if( pBt->pWriter==p ){
|
| + BtLock *pLock;
|
| + pBt->pWriter = 0;
|
| + pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING);
|
| + for(pLock=pBt->pLock; pLock; pLock=pLock->pNext){
|
| + assert( pLock->eLock==READ_LOCK || pLock->pBtree==p );
|
| + pLock->eLock = READ_LOCK;
|
| + }
|
| + }
|
| +}
|
| +
|
| +#endif /* SQLITE_OMIT_SHARED_CACHE */
|
| +
|
| +static void releasePage(MemPage *pPage); /* Forward reference */
|
| +
|
| +/*
|
| +***** This routine is used inside of assert() only ****
|
| +**
|
| +** Verify that the cursor holds the mutex on its BtShared
|
| +*/
|
| +#ifdef SQLITE_DEBUG
|
| +static int cursorHoldsMutex(BtCursor *p){
|
| + return sqlite3_mutex_held(p->pBt->mutex);
|
| +}
|
| +
|
| +/* Verify that the cursor and the BtShared agree about what is the current
|
| +** database connetion. This is important in shared-cache mode. If the database
|
| +** connection pointers get out-of-sync, it is possible for routines like
|
| +** btreeInitPage() to reference an stale connection pointer that references a
|
| +** a connection that has already closed. This routine is used inside assert()
|
| +** statements only and for the purpose of double-checking that the btree code
|
| +** does keep the database connection pointers up-to-date.
|
| +*/
|
| +static int cursorOwnsBtShared(BtCursor *p){
|
| + assert( cursorHoldsMutex(p) );
|
| + return (p->pBtree->db==p->pBt->db);
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Invalidate the overflow cache of the cursor passed as the first argument.
|
| +** on the shared btree structure pBt.
|
| +*/
|
| +#define invalidateOverflowCache(pCur) (pCur->curFlags &= ~BTCF_ValidOvfl)
|
| +
|
| +/*
|
| +** Invalidate the overflow page-list cache for all cursors opened
|
| +** on the shared btree structure pBt.
|
| +*/
|
| +static void invalidateAllOverflowCache(BtShared *pBt){
|
| + BtCursor *p;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + for(p=pBt->pCursor; p; p=p->pNext){
|
| + invalidateOverflowCache(p);
|
| + }
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_INCRBLOB
|
| +/*
|
| +** This function is called before modifying the contents of a table
|
| +** to invalidate any incrblob cursors that are open on the
|
| +** row or one of the rows being modified.
|
| +**
|
| +** If argument isClearTable is true, then the entire contents of the
|
| +** table is about to be deleted. In this case invalidate all incrblob
|
| +** cursors open on any row within the table with root-page pgnoRoot.
|
| +**
|
| +** Otherwise, if argument isClearTable is false, then the row with
|
| +** rowid iRow is being replaced or deleted. In this case invalidate
|
| +** only those incrblob cursors open on that specific row.
|
| +*/
|
| +static void invalidateIncrblobCursors(
|
| + Btree *pBtree, /* The database file to check */
|
| + i64 iRow, /* The rowid that might be changing */
|
| + int isClearTable /* True if all rows are being deleted */
|
| +){
|
| + BtCursor *p;
|
| + if( pBtree->hasIncrblobCur==0 ) return;
|
| + assert( sqlite3BtreeHoldsMutex(pBtree) );
|
| + pBtree->hasIncrblobCur = 0;
|
| + for(p=pBtree->pBt->pCursor; p; p=p->pNext){
|
| + if( (p->curFlags & BTCF_Incrblob)!=0 ){
|
| + pBtree->hasIncrblobCur = 1;
|
| + if( isClearTable || p->info.nKey==iRow ){
|
| + p->eState = CURSOR_INVALID;
|
| + }
|
| + }
|
| + }
|
| +}
|
| +
|
| +#else
|
| + /* Stub function when INCRBLOB is omitted */
|
| + #define invalidateIncrblobCursors(x,y,z)
|
| +#endif /* SQLITE_OMIT_INCRBLOB */
|
| +
|
| +/*
|
| +** Set bit pgno of the BtShared.pHasContent bitvec. This is called
|
| +** when a page that previously contained data becomes a free-list leaf
|
| +** page.
|
| +**
|
| +** The BtShared.pHasContent bitvec exists to work around an obscure
|
| +** bug caused by the interaction of two useful IO optimizations surrounding
|
| +** free-list leaf pages:
|
| +**
|
| +** 1) When all data is deleted from a page and the page becomes
|
| +** a free-list leaf page, the page is not written to the database
|
| +** (as free-list leaf pages contain no meaningful data). Sometimes
|
| +** such a page is not even journalled (as it will not be modified,
|
| +** why bother journalling it?).
|
| +**
|
| +** 2) When a free-list leaf page is reused, its content is not read
|
| +** from the database or written to the journal file (why should it
|
| +** be, if it is not at all meaningful?).
|
| +**
|
| +** By themselves, these optimizations work fine and provide a handy
|
| +** performance boost to bulk delete or insert operations. However, if
|
| +** a page is moved to the free-list and then reused within the same
|
| +** transaction, a problem comes up. If the page is not journalled when
|
| +** it is moved to the free-list and it is also not journalled when it
|
| +** is extracted from the free-list and reused, then the original data
|
| +** may be lost. In the event of a rollback, it may not be possible
|
| +** to restore the database to its original configuration.
|
| +**
|
| +** The solution is the BtShared.pHasContent bitvec. Whenever a page is
|
| +** moved to become a free-list leaf page, the corresponding bit is
|
| +** set in the bitvec. Whenever a leaf page is extracted from the free-list,
|
| +** optimization 2 above is omitted if the corresponding bit is already
|
| +** set in BtShared.pHasContent. The contents of the bitvec are cleared
|
| +** at the end of every transaction.
|
| +*/
|
| +static int btreeSetHasContent(BtShared *pBt, Pgno pgno){
|
| + int rc = SQLITE_OK;
|
| + if( !pBt->pHasContent ){
|
| + assert( pgno<=pBt->nPage );
|
| + pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage);
|
| + if( !pBt->pHasContent ){
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + }
|
| + }
|
| + if( rc==SQLITE_OK && pgno<=sqlite3BitvecSize(pBt->pHasContent) ){
|
| + rc = sqlite3BitvecSet(pBt->pHasContent, pgno);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Query the BtShared.pHasContent vector.
|
| +**
|
| +** This function is called when a free-list leaf page is removed from the
|
| +** free-list for reuse. It returns false if it is safe to retrieve the
|
| +** page from the pager layer with the 'no-content' flag set. True otherwise.
|
| +*/
|
| +static int btreeGetHasContent(BtShared *pBt, Pgno pgno){
|
| + Bitvec *p = pBt->pHasContent;
|
| + return (p && (pgno>sqlite3BitvecSize(p) || sqlite3BitvecTest(p, pgno)));
|
| +}
|
| +
|
| +/*
|
| +** Clear (destroy) the BtShared.pHasContent bitvec. This should be
|
| +** invoked at the conclusion of each write-transaction.
|
| +*/
|
| +static void btreeClearHasContent(BtShared *pBt){
|
| + sqlite3BitvecDestroy(pBt->pHasContent);
|
| + pBt->pHasContent = 0;
|
| +}
|
| +
|
| +/*
|
| +** Release all of the apPage[] pages for a cursor.
|
| +*/
|
| +static void btreeReleaseAllCursorPages(BtCursor *pCur){
|
| + int i;
|
| + for(i=0; i<=pCur->iPage; i++){
|
| + releasePage(pCur->apPage[i]);
|
| + pCur->apPage[i] = 0;
|
| + }
|
| + pCur->iPage = -1;
|
| +}
|
| +
|
| +/*
|
| +** The cursor passed as the only argument must point to a valid entry
|
| +** when this function is called (i.e. have eState==CURSOR_VALID). This
|
| +** function saves the current cursor key in variables pCur->nKey and
|
| +** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error
|
| +** code otherwise.
|
| +**
|
| +** If the cursor is open on an intkey table, then the integer key
|
| +** (the rowid) is stored in pCur->nKey and pCur->pKey is left set to
|
| +** NULL. If the cursor is open on a non-intkey table, then pCur->pKey is
|
| +** set to point to a malloced buffer pCur->nKey bytes in size containing
|
| +** the key.
|
| +*/
|
| +static int saveCursorKey(BtCursor *pCur){
|
| + int rc = SQLITE_OK;
|
| + assert( CURSOR_VALID==pCur->eState );
|
| + assert( 0==pCur->pKey );
|
| + assert( cursorHoldsMutex(pCur) );
|
| +
|
| + if( pCur->curIntKey ){
|
| + /* Only the rowid is required for a table btree */
|
| + pCur->nKey = sqlite3BtreeIntegerKey(pCur);
|
| + }else{
|
| + /* For an index btree, save the complete key content */
|
| + void *pKey;
|
| + pCur->nKey = sqlite3BtreePayloadSize(pCur);
|
| + pKey = sqlite3Malloc( pCur->nKey );
|
| + if( pKey ){
|
| + rc = sqlite3BtreePayload(pCur, 0, (int)pCur->nKey, pKey);
|
| + if( rc==SQLITE_OK ){
|
| + pCur->pKey = pKey;
|
| + }else{
|
| + sqlite3_free(pKey);
|
| + }
|
| + }else{
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + }
|
| + }
|
| + assert( !pCur->curIntKey || !pCur->pKey );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Save the current cursor position in the variables BtCursor.nKey
|
| +** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
|
| +**
|
| +** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
|
| +** prior to calling this routine.
|
| +*/
|
| +static int saveCursorPosition(BtCursor *pCur){
|
| + int rc;
|
| +
|
| + assert( CURSOR_VALID==pCur->eState || CURSOR_SKIPNEXT==pCur->eState );
|
| + assert( 0==pCur->pKey );
|
| + assert( cursorHoldsMutex(pCur) );
|
| +
|
| + if( pCur->eState==CURSOR_SKIPNEXT ){
|
| + pCur->eState = CURSOR_VALID;
|
| + }else{
|
| + pCur->skipNext = 0;
|
| + }
|
| +
|
| + rc = saveCursorKey(pCur);
|
| + if( rc==SQLITE_OK ){
|
| + btreeReleaseAllCursorPages(pCur);
|
| + pCur->eState = CURSOR_REQUIRESEEK;
|
| + }
|
| +
|
| + pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl|BTCF_AtLast);
|
| + return rc;
|
| +}
|
| +
|
| +/* Forward reference */
|
| +static int SQLITE_NOINLINE saveCursorsOnList(BtCursor*,Pgno,BtCursor*);
|
| +
|
| +/*
|
| +** Save the positions of all cursors (except pExcept) that are open on
|
| +** the table with root-page iRoot. "Saving the cursor position" means that
|
| +** the location in the btree is remembered in such a way that it can be
|
| +** moved back to the same spot after the btree has been modified. This
|
| +** routine is called just before cursor pExcept is used to modify the
|
| +** table, for example in BtreeDelete() or BtreeInsert().
|
| +**
|
| +** If there are two or more cursors on the same btree, then all such
|
| +** cursors should have their BTCF_Multiple flag set. The btreeCursor()
|
| +** routine enforces that rule. This routine only needs to be called in
|
| +** the uncommon case when pExpect has the BTCF_Multiple flag set.
|
| +**
|
| +** If pExpect!=NULL and if no other cursors are found on the same root-page,
|
| +** then the BTCF_Multiple flag on pExpect is cleared, to avoid another
|
| +** pointless call to this routine.
|
| +**
|
| +** Implementation note: This routine merely checks to see if any cursors
|
| +** need to be saved. It calls out to saveCursorsOnList() in the (unusual)
|
| +** event that cursors are in need to being saved.
|
| +*/
|
| +static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
|
| + BtCursor *p;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( pExcept==0 || pExcept->pBt==pBt );
|
| + for(p=pBt->pCursor; p; p=p->pNext){
|
| + if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ) break;
|
| + }
|
| + if( p ) return saveCursorsOnList(p, iRoot, pExcept);
|
| + if( pExcept ) pExcept->curFlags &= ~BTCF_Multiple;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/* This helper routine to saveAllCursors does the actual work of saving
|
| +** the cursors if and when a cursor is found that actually requires saving.
|
| +** The common case is that no cursors need to be saved, so this routine is
|
| +** broken out from its caller to avoid unnecessary stack pointer movement.
|
| +*/
|
| +static int SQLITE_NOINLINE saveCursorsOnList(
|
| + BtCursor *p, /* The first cursor that needs saving */
|
| + Pgno iRoot, /* Only save cursor with this iRoot. Save all if zero */
|
| + BtCursor *pExcept /* Do not save this cursor */
|
| +){
|
| + do{
|
| + if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
|
| + if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
|
| + int rc = saveCursorPosition(p);
|
| + if( SQLITE_OK!=rc ){
|
| + return rc;
|
| + }
|
| + }else{
|
| + testcase( p->iPage>0 );
|
| + btreeReleaseAllCursorPages(p);
|
| + }
|
| + }
|
| + p = p->pNext;
|
| + }while( p );
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Clear the current cursor position.
|
| +*/
|
| +void sqlite3BtreeClearCursor(BtCursor *pCur){
|
| + assert( cursorHoldsMutex(pCur) );
|
| + sqlite3_free(pCur->pKey);
|
| + pCur->pKey = 0;
|
| + pCur->eState = CURSOR_INVALID;
|
| +}
|
| +
|
| +/*
|
| +** In this version of BtreeMoveto, pKey is a packed index record
|
| +** such as is generated by the OP_MakeRecord opcode. Unpack the
|
| +** record and then call BtreeMovetoUnpacked() to do the work.
|
| +*/
|
| +static int btreeMoveto(
|
| + BtCursor *pCur, /* Cursor open on the btree to be searched */
|
| + const void *pKey, /* Packed key if the btree is an index */
|
| + i64 nKey, /* Integer key for tables. Size of pKey for indices */
|
| + int bias, /* Bias search to the high end */
|
| + int *pRes /* Write search results here */
|
| +){
|
| + int rc; /* Status code */
|
| + UnpackedRecord *pIdxKey; /* Unpacked index key */
|
| +
|
| + if( pKey ){
|
| + assert( nKey==(i64)(int)nKey );
|
| + pIdxKey = sqlite3VdbeAllocUnpackedRecord(pCur->pKeyInfo);
|
| + if( pIdxKey==0 ) return SQLITE_NOMEM_BKPT;
|
| + sqlite3VdbeRecordUnpack(pCur->pKeyInfo, (int)nKey, pKey, pIdxKey);
|
| + if( pIdxKey->nField==0 ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto moveto_done;
|
| + }
|
| + }else{
|
| + pIdxKey = 0;
|
| + }
|
| + rc = sqlite3BtreeMovetoUnpacked(pCur, pIdxKey, nKey, bias, pRes);
|
| +moveto_done:
|
| + if( pIdxKey ){
|
| + sqlite3DbFree(pCur->pKeyInfo->db, pIdxKey);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Restore the cursor to the position it was in (or as close to as possible)
|
| +** when saveCursorPosition() was called. Note that this call deletes the
|
| +** saved position info stored by saveCursorPosition(), so there can be
|
| +** at most one effective restoreCursorPosition() call after each
|
| +** saveCursorPosition().
|
| +*/
|
| +static int btreeRestoreCursorPosition(BtCursor *pCur){
|
| + int rc;
|
| + int skipNext;
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->eState>=CURSOR_REQUIRESEEK );
|
| + if( pCur->eState==CURSOR_FAULT ){
|
| + return pCur->skipNext;
|
| + }
|
| + pCur->eState = CURSOR_INVALID;
|
| + rc = btreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &skipNext);
|
| + if( rc==SQLITE_OK ){
|
| + sqlite3_free(pCur->pKey);
|
| + pCur->pKey = 0;
|
| + assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
|
| + pCur->skipNext |= skipNext;
|
| + if( pCur->skipNext && pCur->eState==CURSOR_VALID ){
|
| + pCur->eState = CURSOR_SKIPNEXT;
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +#define restoreCursorPosition(p) \
|
| + (p->eState>=CURSOR_REQUIRESEEK ? \
|
| + btreeRestoreCursorPosition(p) : \
|
| + SQLITE_OK)
|
| +
|
| +/*
|
| +** Determine whether or not a cursor has moved from the position where
|
| +** it was last placed, or has been invalidated for any other reason.
|
| +** Cursors can move when the row they are pointing at is deleted out
|
| +** from under them, for example. Cursor might also move if a btree
|
| +** is rebalanced.
|
| +**
|
| +** Calling this routine with a NULL cursor pointer returns false.
|
| +**
|
| +** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor
|
| +** back to where it ought to be if this routine returns true.
|
| +*/
|
| +int sqlite3BtreeCursorHasMoved(BtCursor *pCur){
|
| + return pCur->eState!=CURSOR_VALID;
|
| +}
|
| +
|
| +/*
|
| +** This routine restores a cursor back to its original position after it
|
| +** has been moved by some outside activity (such as a btree rebalance or
|
| +** a row having been deleted out from under the cursor).
|
| +**
|
| +** On success, the *pDifferentRow parameter is false if the cursor is left
|
| +** pointing at exactly the same row. *pDifferntRow is the row the cursor
|
| +** was pointing to has been deleted, forcing the cursor to point to some
|
| +** nearby row.
|
| +**
|
| +** This routine should only be called for a cursor that just returned
|
| +** TRUE from sqlite3BtreeCursorHasMoved().
|
| +*/
|
| +int sqlite3BtreeCursorRestore(BtCursor *pCur, int *pDifferentRow){
|
| + int rc;
|
| +
|
| + assert( pCur!=0 );
|
| + assert( pCur->eState!=CURSOR_VALID );
|
| + rc = restoreCursorPosition(pCur);
|
| + if( rc ){
|
| + *pDifferentRow = 1;
|
| + return rc;
|
| + }
|
| + if( pCur->eState!=CURSOR_VALID ){
|
| + *pDifferentRow = 1;
|
| + }else{
|
| + assert( pCur->skipNext==0 );
|
| + *pDifferentRow = 0;
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +#ifdef SQLITE_ENABLE_CURSOR_HINTS
|
| +/*
|
| +** Provide hints to the cursor. The particular hint given (and the type
|
| +** and number of the varargs parameters) is determined by the eHintType
|
| +** parameter. See the definitions of the BTREE_HINT_* macros for details.
|
| +*/
|
| +void sqlite3BtreeCursorHint(BtCursor *pCur, int eHintType, ...){
|
| + /* Used only by system that substitute their own storage engine */
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Provide flag hints to the cursor.
|
| +*/
|
| +void sqlite3BtreeCursorHintFlags(BtCursor *pCur, unsigned x){
|
| + assert( x==BTREE_SEEK_EQ || x==BTREE_BULKLOAD || x==0 );
|
| + pCur->hints = x;
|
| +}
|
| +
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +/*
|
| +** Given a page number of a regular database page, return the page
|
| +** number for the pointer-map page that contains the entry for the
|
| +** input page number.
|
| +**
|
| +** Return 0 (not a valid page) for pgno==1 since there is
|
| +** no pointer map associated with page 1. The integrity_check logic
|
| +** requires that ptrmapPageno(*,1)!=1.
|
| +*/
|
| +static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
|
| + int nPagesPerMapPage;
|
| + Pgno iPtrMap, ret;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + if( pgno<2 ) return 0;
|
| + nPagesPerMapPage = (pBt->usableSize/5)+1;
|
| + iPtrMap = (pgno-2)/nPagesPerMapPage;
|
| + ret = (iPtrMap*nPagesPerMapPage) + 2;
|
| + if( ret==PENDING_BYTE_PAGE(pBt) ){
|
| + ret++;
|
| + }
|
| + return ret;
|
| +}
|
| +
|
| +/*
|
| +** Write an entry into the pointer map.
|
| +**
|
| +** This routine updates the pointer map entry for page number 'key'
|
| +** so that it maps to type 'eType' and parent page number 'pgno'.
|
| +**
|
| +** If *pRC is initially non-zero (non-SQLITE_OK) then this routine is
|
| +** a no-op. If an error occurs, the appropriate error code is written
|
| +** into *pRC.
|
| +*/
|
| +static void ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent, int *pRC){
|
| + DbPage *pDbPage; /* The pointer map page */
|
| + u8 *pPtrmap; /* The pointer map data */
|
| + Pgno iPtrmap; /* The pointer map page number */
|
| + int offset; /* Offset in pointer map page */
|
| + int rc; /* Return code from subfunctions */
|
| +
|
| + if( *pRC ) return;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + /* The master-journal page number must never be used as a pointer map page */
|
| + assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );
|
| +
|
| + assert( pBt->autoVacuum );
|
| + if( key==0 ){
|
| + *pRC = SQLITE_CORRUPT_BKPT;
|
| + return;
|
| + }
|
| + iPtrmap = PTRMAP_PAGENO(pBt, key);
|
| + rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + *pRC = rc;
|
| + return;
|
| + }
|
| + offset = PTRMAP_PTROFFSET(iPtrmap, key);
|
| + if( offset<0 ){
|
| + *pRC = SQLITE_CORRUPT_BKPT;
|
| + goto ptrmap_exit;
|
| + }
|
| + assert( offset <= (int)pBt->usableSize-5 );
|
| + pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
|
| +
|
| + if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
|
| + TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
|
| + *pRC= rc = sqlite3PagerWrite(pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + pPtrmap[offset] = eType;
|
| + put4byte(&pPtrmap[offset+1], parent);
|
| + }
|
| + }
|
| +
|
| +ptrmap_exit:
|
| + sqlite3PagerUnref(pDbPage);
|
| +}
|
| +
|
| +/*
|
| +** Read an entry from the pointer map.
|
| +**
|
| +** This routine retrieves the pointer map entry for page 'key', writing
|
| +** the type and parent page number to *pEType and *pPgno respectively.
|
| +** An error code is returned if something goes wrong, otherwise SQLITE_OK.
|
| +*/
|
| +static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
|
| + DbPage *pDbPage; /* The pointer map page */
|
| + int iPtrmap; /* Pointer map page index */
|
| + u8 *pPtrmap; /* Pointer map page data */
|
| + int offset; /* Offset of entry in pointer map */
|
| + int rc;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| +
|
| + iPtrmap = PTRMAP_PAGENO(pBt, key);
|
| + rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0);
|
| + if( rc!=0 ){
|
| + return rc;
|
| + }
|
| + pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
|
| +
|
| + offset = PTRMAP_PTROFFSET(iPtrmap, key);
|
| + if( offset<0 ){
|
| + sqlite3PagerUnref(pDbPage);
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + assert( offset <= (int)pBt->usableSize-5 );
|
| + assert( pEType!=0 );
|
| + *pEType = pPtrmap[offset];
|
| + if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);
|
| +
|
| + sqlite3PagerUnref(pDbPage);
|
| + if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +#else /* if defined SQLITE_OMIT_AUTOVACUUM */
|
| + #define ptrmapPut(w,x,y,z,rc)
|
| + #define ptrmapGet(w,x,y,z) SQLITE_OK
|
| + #define ptrmapPutOvflPtr(x, y, rc)
|
| +#endif
|
| +
|
| +/*
|
| +** Given a btree page and a cell index (0 means the first cell on
|
| +** the page, 1 means the second cell, and so forth) return a pointer
|
| +** to the cell content.
|
| +**
|
| +** findCellPastPtr() does the same except it skips past the initial
|
| +** 4-byte child pointer found on interior pages, if there is one.
|
| +**
|
| +** This routine works only for pages that do not contain overflow cells.
|
| +*/
|
| +#define findCell(P,I) \
|
| + ((P)->aData + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)])))
|
| +#define findCellPastPtr(P,I) \
|
| + ((P)->aDataOfst + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)])))
|
| +
|
| +
|
| +/*
|
| +** This is common tail processing for btreeParseCellPtr() and
|
| +** btreeParseCellPtrIndex() for the case when the cell does not fit entirely
|
| +** on a single B-tree page. Make necessary adjustments to the CellInfo
|
| +** structure.
|
| +*/
|
| +static SQLITE_NOINLINE void btreeParseCellAdjustSizeForOverflow(
|
| + MemPage *pPage, /* Page containing the cell */
|
| + u8 *pCell, /* Pointer to the cell text. */
|
| + CellInfo *pInfo /* Fill in this structure */
|
| +){
|
| + /* If the payload will not fit completely on the local page, we have
|
| + ** to decide how much to store locally and how much to spill onto
|
| + ** overflow pages. The strategy is to minimize the amount of unused
|
| + ** space on overflow pages while keeping the amount of local storage
|
| + ** in between minLocal and maxLocal.
|
| + **
|
| + ** Warning: changing the way overflow payload is distributed in any
|
| + ** way will result in an incompatible file format.
|
| + */
|
| + int minLocal; /* Minimum amount of payload held locally */
|
| + int maxLocal; /* Maximum amount of payload held locally */
|
| + int surplus; /* Overflow payload available for local storage */
|
| +
|
| + minLocal = pPage->minLocal;
|
| + maxLocal = pPage->maxLocal;
|
| + surplus = minLocal + (pInfo->nPayload - minLocal)%(pPage->pBt->usableSize-4);
|
| + testcase( surplus==maxLocal );
|
| + testcase( surplus==maxLocal+1 );
|
| + if( surplus <= maxLocal ){
|
| + pInfo->nLocal = (u16)surplus;
|
| + }else{
|
| + pInfo->nLocal = (u16)minLocal;
|
| + }
|
| + pInfo->nSize = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell) + 4;
|
| +}
|
| +
|
| +/*
|
| +** The following routines are implementations of the MemPage.xParseCell()
|
| +** method.
|
| +**
|
| +** Parse a cell content block and fill in the CellInfo structure.
|
| +**
|
| +** btreeParseCellPtr() => table btree leaf nodes
|
| +** btreeParseCellNoPayload() => table btree internal nodes
|
| +** btreeParseCellPtrIndex() => index btree nodes
|
| +**
|
| +** There is also a wrapper function btreeParseCell() that works for
|
| +** all MemPage types and that references the cell by index rather than
|
| +** by pointer.
|
| +*/
|
| +static void btreeParseCellPtrNoPayload(
|
| + MemPage *pPage, /* Page containing the cell */
|
| + u8 *pCell, /* Pointer to the cell text. */
|
| + CellInfo *pInfo /* Fill in this structure */
|
| +){
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( pPage->leaf==0 );
|
| + assert( pPage->childPtrSize==4 );
|
| +#ifndef SQLITE_DEBUG
|
| + UNUSED_PARAMETER(pPage);
|
| +#endif
|
| + pInfo->nSize = 4 + getVarint(&pCell[4], (u64*)&pInfo->nKey);
|
| + pInfo->nPayload = 0;
|
| + pInfo->nLocal = 0;
|
| + pInfo->pPayload = 0;
|
| + return;
|
| +}
|
| +static void btreeParseCellPtr(
|
| + MemPage *pPage, /* Page containing the cell */
|
| + u8 *pCell, /* Pointer to the cell text. */
|
| + CellInfo *pInfo /* Fill in this structure */
|
| +){
|
| + u8 *pIter; /* For scanning through pCell */
|
| + u32 nPayload; /* Number of bytes of cell payload */
|
| + u64 iKey; /* Extracted Key value */
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( pPage->leaf==0 || pPage->leaf==1 );
|
| + assert( pPage->intKeyLeaf );
|
| + assert( pPage->childPtrSize==0 );
|
| + pIter = pCell;
|
| +
|
| + /* The next block of code is equivalent to:
|
| + **
|
| + ** pIter += getVarint32(pIter, nPayload);
|
| + **
|
| + ** The code is inlined to avoid a function call.
|
| + */
|
| + nPayload = *pIter;
|
| + if( nPayload>=0x80 ){
|
| + u8 *pEnd = &pIter[8];
|
| + nPayload &= 0x7f;
|
| + do{
|
| + nPayload = (nPayload<<7) | (*++pIter & 0x7f);
|
| + }while( (*pIter)>=0x80 && pIter<pEnd );
|
| + }
|
| + pIter++;
|
| +
|
| + /* The next block of code is equivalent to:
|
| + **
|
| + ** pIter += getVarint(pIter, (u64*)&pInfo->nKey);
|
| + **
|
| + ** The code is inlined to avoid a function call.
|
| + */
|
| + iKey = *pIter;
|
| + if( iKey>=0x80 ){
|
| + u8 *pEnd = &pIter[7];
|
| + iKey &= 0x7f;
|
| + while(1){
|
| + iKey = (iKey<<7) | (*++pIter & 0x7f);
|
| + if( (*pIter)<0x80 ) break;
|
| + if( pIter>=pEnd ){
|
| + iKey = (iKey<<8) | *++pIter;
|
| + break;
|
| + }
|
| + }
|
| + }
|
| + pIter++;
|
| +
|
| + pInfo->nKey = *(i64*)&iKey;
|
| + pInfo->nPayload = nPayload;
|
| + pInfo->pPayload = pIter;
|
| + testcase( nPayload==pPage->maxLocal );
|
| + testcase( nPayload==pPage->maxLocal+1 );
|
| + if( nPayload<=pPage->maxLocal ){
|
| + /* This is the (easy) common case where the entire payload fits
|
| + ** on the local page. No overflow is required.
|
| + */
|
| + pInfo->nSize = nPayload + (u16)(pIter - pCell);
|
| + if( pInfo->nSize<4 ) pInfo->nSize = 4;
|
| + pInfo->nLocal = (u16)nPayload;
|
| + }else{
|
| + btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
|
| + }
|
| +}
|
| +static void btreeParseCellPtrIndex(
|
| + MemPage *pPage, /* Page containing the cell */
|
| + u8 *pCell, /* Pointer to the cell text. */
|
| + CellInfo *pInfo /* Fill in this structure */
|
| +){
|
| + u8 *pIter; /* For scanning through pCell */
|
| + u32 nPayload; /* Number of bytes of cell payload */
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( pPage->leaf==0 || pPage->leaf==1 );
|
| + assert( pPage->intKeyLeaf==0 );
|
| + pIter = pCell + pPage->childPtrSize;
|
| + nPayload = *pIter;
|
| + if( nPayload>=0x80 ){
|
| + u8 *pEnd = &pIter[8];
|
| + nPayload &= 0x7f;
|
| + do{
|
| + nPayload = (nPayload<<7) | (*++pIter & 0x7f);
|
| + }while( *(pIter)>=0x80 && pIter<pEnd );
|
| + }
|
| + pIter++;
|
| + pInfo->nKey = nPayload;
|
| + pInfo->nPayload = nPayload;
|
| + pInfo->pPayload = pIter;
|
| + testcase( nPayload==pPage->maxLocal );
|
| + testcase( nPayload==pPage->maxLocal+1 );
|
| + if( nPayload<=pPage->maxLocal ){
|
| + /* This is the (easy) common case where the entire payload fits
|
| + ** on the local page. No overflow is required.
|
| + */
|
| + pInfo->nSize = nPayload + (u16)(pIter - pCell);
|
| + if( pInfo->nSize<4 ) pInfo->nSize = 4;
|
| + pInfo->nLocal = (u16)nPayload;
|
| + }else{
|
| + btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
|
| + }
|
| +}
|
| +static void btreeParseCell(
|
| + MemPage *pPage, /* Page containing the cell */
|
| + int iCell, /* The cell index. First cell is 0 */
|
| + CellInfo *pInfo /* Fill in this structure */
|
| +){
|
| + pPage->xParseCell(pPage, findCell(pPage, iCell), pInfo);
|
| +}
|
| +
|
| +/*
|
| +** The following routines are implementations of the MemPage.xCellSize
|
| +** method.
|
| +**
|
| +** Compute the total number of bytes that a Cell needs in the cell
|
| +** data area of the btree-page. The return number includes the cell
|
| +** data header and the local payload, but not any overflow page or
|
| +** the space used by the cell pointer.
|
| +**
|
| +** cellSizePtrNoPayload() => table internal nodes
|
| +** cellSizePtr() => all index nodes & table leaf nodes
|
| +*/
|
| +static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
|
| + u8 *pIter = pCell + pPage->childPtrSize; /* For looping over bytes of pCell */
|
| + u8 *pEnd; /* End mark for a varint */
|
| + u32 nSize; /* Size value to return */
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| + /* The value returned by this function should always be the same as
|
| + ** the (CellInfo.nSize) value found by doing a full parse of the
|
| + ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
|
| + ** this function verifies that this invariant is not violated. */
|
| + CellInfo debuginfo;
|
| + pPage->xParseCell(pPage, pCell, &debuginfo);
|
| +#endif
|
| +
|
| + nSize = *pIter;
|
| + if( nSize>=0x80 ){
|
| + pEnd = &pIter[8];
|
| + nSize &= 0x7f;
|
| + do{
|
| + nSize = (nSize<<7) | (*++pIter & 0x7f);
|
| + }while( *(pIter)>=0x80 && pIter<pEnd );
|
| + }
|
| + pIter++;
|
| + if( pPage->intKey ){
|
| + /* pIter now points at the 64-bit integer key value, a variable length
|
| + ** integer. The following block moves pIter to point at the first byte
|
| + ** past the end of the key value. */
|
| + pEnd = &pIter[9];
|
| + while( (*pIter++)&0x80 && pIter<pEnd );
|
| + }
|
| + testcase( nSize==pPage->maxLocal );
|
| + testcase( nSize==pPage->maxLocal+1 );
|
| + if( nSize<=pPage->maxLocal ){
|
| + nSize += (u32)(pIter - pCell);
|
| + if( nSize<4 ) nSize = 4;
|
| + }else{
|
| + int minLocal = pPage->minLocal;
|
| + nSize = minLocal + (nSize - minLocal) % (pPage->pBt->usableSize - 4);
|
| + testcase( nSize==pPage->maxLocal );
|
| + testcase( nSize==pPage->maxLocal+1 );
|
| + if( nSize>pPage->maxLocal ){
|
| + nSize = minLocal;
|
| + }
|
| + nSize += 4 + (u16)(pIter - pCell);
|
| + }
|
| + assert( nSize==debuginfo.nSize || CORRUPT_DB );
|
| + return (u16)nSize;
|
| +}
|
| +static u16 cellSizePtrNoPayload(MemPage *pPage, u8 *pCell){
|
| + u8 *pIter = pCell + 4; /* For looping over bytes of pCell */
|
| + u8 *pEnd; /* End mark for a varint */
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| + /* The value returned by this function should always be the same as
|
| + ** the (CellInfo.nSize) value found by doing a full parse of the
|
| + ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
|
| + ** this function verifies that this invariant is not violated. */
|
| + CellInfo debuginfo;
|
| + pPage->xParseCell(pPage, pCell, &debuginfo);
|
| +#else
|
| + UNUSED_PARAMETER(pPage);
|
| +#endif
|
| +
|
| + assert( pPage->childPtrSize==4 );
|
| + pEnd = pIter + 9;
|
| + while( (*pIter++)&0x80 && pIter<pEnd );
|
| + assert( debuginfo.nSize==(u16)(pIter - pCell) || CORRUPT_DB );
|
| + return (u16)(pIter - pCell);
|
| +}
|
| +
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| +/* This variation on cellSizePtr() is used inside of assert() statements
|
| +** only. */
|
| +static u16 cellSize(MemPage *pPage, int iCell){
|
| + return pPage->xCellSize(pPage, findCell(pPage, iCell));
|
| +}
|
| +#endif
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +/*
|
| +** If the cell pCell, part of page pPage contains a pointer
|
| +** to an overflow page, insert an entry into the pointer-map
|
| +** for the overflow page.
|
| +*/
|
| +static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
|
| + CellInfo info;
|
| + if( *pRC ) return;
|
| + assert( pCell!=0 );
|
| + pPage->xParseCell(pPage, pCell, &info);
|
| + if( info.nLocal<info.nPayload ){
|
| + Pgno ovfl = get4byte(&pCell[info.nSize-4]);
|
| + ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
|
| + }
|
| +}
|
| +#endif
|
| +
|
| +
|
| +/*
|
| +** Defragment the page given. All Cells are moved to the
|
| +** end of the page and all free space is collected into one
|
| +** big FreeBlk that occurs in between the header and cell
|
| +** pointer array and the cell content area.
|
| +**
|
| +** EVIDENCE-OF: R-44582-60138 SQLite may from time to time reorganize a
|
| +** b-tree page so that there are no freeblocks or fragment bytes, all
|
| +** unused bytes are contained in the unallocated space region, and all
|
| +** cells are packed tightly at the end of the page.
|
| +*/
|
| +static int defragmentPage(MemPage *pPage){
|
| + int i; /* Loop counter */
|
| + int pc; /* Address of the i-th cell */
|
| + int hdr; /* Offset to the page header */
|
| + int size; /* Size of a cell */
|
| + int usableSize; /* Number of usable bytes on a page */
|
| + int cellOffset; /* Offset to the cell pointer array */
|
| + int cbrk; /* Offset to the cell content area */
|
| + int nCell; /* Number of cells on the page */
|
| + unsigned char *data; /* The page data */
|
| + unsigned char *temp; /* Temp area for cell content */
|
| + unsigned char *src; /* Source of content */
|
| + int iCellFirst; /* First allowable cell index */
|
| + int iCellLast; /* Last possible cell index */
|
| +
|
| +
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + assert( pPage->pBt!=0 );
|
| + assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
|
| + assert( pPage->nOverflow==0 );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + temp = 0;
|
| + src = data = pPage->aData;
|
| + hdr = pPage->hdrOffset;
|
| + cellOffset = pPage->cellOffset;
|
| + nCell = pPage->nCell;
|
| + assert( nCell==get2byte(&data[hdr+3]) );
|
| + usableSize = pPage->pBt->usableSize;
|
| + cbrk = usableSize;
|
| + iCellFirst = cellOffset + 2*nCell;
|
| + iCellLast = usableSize - 4;
|
| + for(i=0; i<nCell; i++){
|
| + u8 *pAddr; /* The i-th cell pointer */
|
| + pAddr = &data[cellOffset + i*2];
|
| + pc = get2byte(pAddr);
|
| + testcase( pc==iCellFirst );
|
| + testcase( pc==iCellLast );
|
| + /* These conditions have already been verified in btreeInitPage()
|
| + ** if PRAGMA cell_size_check=ON.
|
| + */
|
| + if( pc<iCellFirst || pc>iCellLast ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + assert( pc>=iCellFirst && pc<=iCellLast );
|
| + size = pPage->xCellSize(pPage, &src[pc]);
|
| + cbrk -= size;
|
| + if( cbrk<iCellFirst || pc+size>usableSize ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
|
| + testcase( cbrk+size==usableSize );
|
| + testcase( pc+size==usableSize );
|
| + put2byte(pAddr, cbrk);
|
| + if( temp==0 ){
|
| + int x;
|
| + if( cbrk==pc ) continue;
|
| + temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
|
| + x = get2byte(&data[hdr+5]);
|
| + memcpy(&temp[x], &data[x], (cbrk+size) - x);
|
| + src = temp;
|
| + }
|
| + memcpy(&data[cbrk], &src[pc], size);
|
| + }
|
| + assert( cbrk>=iCellFirst );
|
| + put2byte(&data[hdr+5], cbrk);
|
| + data[hdr+1] = 0;
|
| + data[hdr+2] = 0;
|
| + data[hdr+7] = 0;
|
| + memset(&data[iCellFirst], 0, cbrk-iCellFirst);
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + if( cbrk-iCellFirst!=pPage->nFree ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Search the free-list on page pPg for space to store a cell nByte bytes in
|
| +** size. If one can be found, return a pointer to the space and remove it
|
| +** from the free-list.
|
| +**
|
| +** If no suitable space can be found on the free-list, return NULL.
|
| +**
|
| +** This function may detect corruption within pPg. If corruption is
|
| +** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned.
|
| +**
|
| +** Slots on the free list that are between 1 and 3 bytes larger than nByte
|
| +** will be ignored if adding the extra space to the fragmentation count
|
| +** causes the fragmentation count to exceed 60.
|
| +*/
|
| +static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
|
| + const int hdr = pPg->hdrOffset;
|
| + u8 * const aData = pPg->aData;
|
| + int iAddr = hdr + 1;
|
| + int pc = get2byte(&aData[iAddr]);
|
| + int x;
|
| + int usableSize = pPg->pBt->usableSize;
|
| +
|
| + assert( pc>0 );
|
| + do{
|
| + int size; /* Size of the free slot */
|
| + /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
|
| + ** increasing offset. */
|
| + if( pc>usableSize-4 || pc<iAddr+4 ){
|
| + *pRc = SQLITE_CORRUPT_BKPT;
|
| + return 0;
|
| + }
|
| + /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
|
| + ** freeblock form a big-endian integer which is the size of the freeblock
|
| + ** in bytes, including the 4-byte header. */
|
| + size = get2byte(&aData[pc+2]);
|
| + if( (x = size - nByte)>=0 ){
|
| + testcase( x==4 );
|
| + testcase( x==3 );
|
| + if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
|
| + *pRc = SQLITE_CORRUPT_BKPT;
|
| + return 0;
|
| + }else if( x<4 ){
|
| + /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
|
| + ** number of bytes in fragments may not exceed 60. */
|
| + if( aData[hdr+7]>57 ) return 0;
|
| +
|
| + /* Remove the slot from the free-list. Update the number of
|
| + ** fragmented bytes within the page. */
|
| + memcpy(&aData[iAddr], &aData[pc], 2);
|
| + aData[hdr+7] += (u8)x;
|
| + }else{
|
| + /* The slot remains on the free-list. Reduce its size to account
|
| + ** for the portion used by the new allocation. */
|
| + put2byte(&aData[pc+2], x);
|
| + }
|
| + return &aData[pc + x];
|
| + }
|
| + iAddr = pc;
|
| + pc = get2byte(&aData[pc]);
|
| + }while( pc );
|
| +
|
| + return 0;
|
| +}
|
| +
|
| +/*
|
| +** Allocate nByte bytes of space from within the B-Tree page passed
|
| +** as the first argument. Write into *pIdx the index into pPage->aData[]
|
| +** of the first byte of allocated space. Return either SQLITE_OK or
|
| +** an error code (usually SQLITE_CORRUPT).
|
| +**
|
| +** The caller guarantees that there is sufficient space to make the
|
| +** allocation. This routine might need to defragment in order to bring
|
| +** all the space together, however. This routine will avoid using
|
| +** the first two bytes past the cell pointer area since presumably this
|
| +** allocation is being made in order to insert a new cell, so we will
|
| +** also end up needing a new cell pointer.
|
| +*/
|
| +static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
|
| + const int hdr = pPage->hdrOffset; /* Local cache of pPage->hdrOffset */
|
| + u8 * const data = pPage->aData; /* Local cache of pPage->aData */
|
| + int top; /* First byte of cell content area */
|
| + int rc = SQLITE_OK; /* Integer return code */
|
| + int gap; /* First byte of gap between cell pointers and cell content */
|
| +
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + assert( pPage->pBt );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( nByte>=0 ); /* Minimum cell size is 4 */
|
| + assert( pPage->nFree>=nByte );
|
| + assert( pPage->nOverflow==0 );
|
| + assert( nByte < (int)(pPage->pBt->usableSize-8) );
|
| +
|
| + assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
|
| + gap = pPage->cellOffset + 2*pPage->nCell;
|
| + assert( gap<=65536 );
|
| + /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size
|
| + ** and the reserved space is zero (the usual value for reserved space)
|
| + ** then the cell content offset of an empty page wants to be 65536.
|
| + ** However, that integer is too large to be stored in a 2-byte unsigned
|
| + ** integer, so a value of 0 is used in its place. */
|
| + top = get2byte(&data[hdr+5]);
|
| + assert( top<=(int)pPage->pBt->usableSize ); /* Prevent by getAndInitPage() */
|
| + if( gap>top ){
|
| + if( top==0 && pPage->pBt->usableSize==65536 ){
|
| + top = 65536;
|
| + }else{
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + }
|
| +
|
| + /* If there is enough space between gap and top for one more cell pointer
|
| + ** array entry offset, and if the freelist is not empty, then search the
|
| + ** freelist looking for a free slot big enough to satisfy the request.
|
| + */
|
| + testcase( gap+2==top );
|
| + testcase( gap+1==top );
|
| + testcase( gap==top );
|
| + if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){
|
| + u8 *pSpace = pageFindSlot(pPage, nByte, &rc);
|
| + if( pSpace ){
|
| + assert( pSpace>=data && (pSpace - data)<65536 );
|
| + *pIdx = (int)(pSpace - data);
|
| + return SQLITE_OK;
|
| + }else if( rc ){
|
| + return rc;
|
| + }
|
| + }
|
| +
|
| + /* The request could not be fulfilled using a freelist slot. Check
|
| + ** to see if defragmentation is necessary.
|
| + */
|
| + testcase( gap+2+nByte==top );
|
| + if( gap+2+nByte>top ){
|
| + assert( pPage->nCell>0 || CORRUPT_DB );
|
| + rc = defragmentPage(pPage);
|
| + if( rc ) return rc;
|
| + top = get2byteNotZero(&data[hdr+5]);
|
| + assert( gap+nByte<=top );
|
| + }
|
| +
|
| +
|
| + /* Allocate memory from the gap in between the cell pointer array
|
| + ** and the cell content area. The btreeInitPage() call has already
|
| + ** validated the freelist. Given that the freelist is valid, there
|
| + ** is no way that the allocation can extend off the end of the page.
|
| + ** The assert() below verifies the previous sentence.
|
| + */
|
| + top -= nByte;
|
| + put2byte(&data[hdr+5], top);
|
| + assert( top+nByte <= (int)pPage->pBt->usableSize );
|
| + *pIdx = top;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Return a section of the pPage->aData to the freelist.
|
| +** The first byte of the new free block is pPage->aData[iStart]
|
| +** and the size of the block is iSize bytes.
|
| +**
|
| +** Adjacent freeblocks are coalesced.
|
| +**
|
| +** Note that even though the freeblock list was checked by btreeInitPage(),
|
| +** that routine will not detect overlap between cells or freeblocks. Nor
|
| +** does it detect cells or freeblocks that encrouch into the reserved bytes
|
| +** at the end of the page. So do additional corruption checks inside this
|
| +** routine and return SQLITE_CORRUPT if any problems are found.
|
| +*/
|
| +static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
|
| + u16 iPtr; /* Address of ptr to next freeblock */
|
| + u16 iFreeBlk; /* Address of the next freeblock */
|
| + u8 hdr; /* Page header size. 0 or 100 */
|
| + u8 nFrag = 0; /* Reduction in fragmentation */
|
| + u16 iOrigSize = iSize; /* Original value of iSize */
|
| + u32 iLast = pPage->pBt->usableSize-4; /* Largest possible freeblock offset */
|
| + u32 iEnd = iStart + iSize; /* First byte past the iStart buffer */
|
| + unsigned char *data = pPage->aData; /* Page content */
|
| +
|
| + assert( pPage->pBt!=0 );
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + assert( CORRUPT_DB || iStart>=pPage->hdrOffset+6+pPage->childPtrSize );
|
| + assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( iSize>=4 ); /* Minimum cell size is 4 */
|
| + assert( iStart<=iLast );
|
| +
|
| + /* Overwrite deleted information with zeros when the secure_delete
|
| + ** option is enabled */
|
| + if( pPage->pBt->btsFlags & BTS_SECURE_DELETE ){
|
| + memset(&data[iStart], 0, iSize);
|
| + }
|
| +
|
| + /* The list of freeblocks must be in ascending order. Find the
|
| + ** spot on the list where iStart should be inserted.
|
| + */
|
| + hdr = pPage->hdrOffset;
|
| + iPtr = hdr + 1;
|
| + if( data[iPtr+1]==0 && data[iPtr]==0 ){
|
| + iFreeBlk = 0; /* Shortcut for the case when the freelist is empty */
|
| + }else{
|
| + while( (iFreeBlk = get2byte(&data[iPtr]))<iStart ){
|
| + if( iFreeBlk<iPtr+4 ){
|
| + if( iFreeBlk==0 ) break;
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + iPtr = iFreeBlk;
|
| + }
|
| + if( iFreeBlk>iLast ) return SQLITE_CORRUPT_BKPT;
|
| + assert( iFreeBlk>iPtr || iFreeBlk==0 );
|
| +
|
| + /* At this point:
|
| + ** iFreeBlk: First freeblock after iStart, or zero if none
|
| + ** iPtr: The address of a pointer to iFreeBlk
|
| + **
|
| + ** Check to see if iFreeBlk should be coalesced onto the end of iStart.
|
| + */
|
| + if( iFreeBlk && iEnd+3>=iFreeBlk ){
|
| + nFrag = iFreeBlk - iEnd;
|
| + if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_BKPT;
|
| + iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]);
|
| + if( iEnd > pPage->pBt->usableSize ) return SQLITE_CORRUPT_BKPT;
|
| + iSize = iEnd - iStart;
|
| + iFreeBlk = get2byte(&data[iFreeBlk]);
|
| + }
|
| +
|
| + /* If iPtr is another freeblock (that is, if iPtr is not the freelist
|
| + ** pointer in the page header) then check to see if iStart should be
|
| + ** coalesced onto the end of iPtr.
|
| + */
|
| + if( iPtr>hdr+1 ){
|
| + int iPtrEnd = iPtr + get2byte(&data[iPtr+2]);
|
| + if( iPtrEnd+3>=iStart ){
|
| + if( iPtrEnd>iStart ) return SQLITE_CORRUPT_BKPT;
|
| + nFrag += iStart - iPtrEnd;
|
| + iSize = iEnd - iPtr;
|
| + iStart = iPtr;
|
| + }
|
| + }
|
| + if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_BKPT;
|
| + data[hdr+7] -= nFrag;
|
| + }
|
| + if( iStart==get2byte(&data[hdr+5]) ){
|
| + /* The new freeblock is at the beginning of the cell content area,
|
| + ** so just extend the cell content area rather than create another
|
| + ** freelist entry */
|
| + if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_BKPT;
|
| + put2byte(&data[hdr+1], iFreeBlk);
|
| + put2byte(&data[hdr+5], iEnd);
|
| + }else{
|
| + /* Insert the new freeblock into the freelist */
|
| + put2byte(&data[iPtr], iStart);
|
| + put2byte(&data[iStart], iFreeBlk);
|
| + put2byte(&data[iStart+2], iSize);
|
| + }
|
| + pPage->nFree += iOrigSize;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Decode the flags byte (the first byte of the header) for a page
|
| +** and initialize fields of the MemPage structure accordingly.
|
| +**
|
| +** Only the following combinations are supported. Anything different
|
| +** indicates a corrupt database files:
|
| +**
|
| +** PTF_ZERODATA
|
| +** PTF_ZERODATA | PTF_LEAF
|
| +** PTF_LEAFDATA | PTF_INTKEY
|
| +** PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF
|
| +*/
|
| +static int decodeFlags(MemPage *pPage, int flagByte){
|
| + BtShared *pBt; /* A copy of pPage->pBt */
|
| +
|
| + assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + pPage->leaf = (u8)(flagByte>>3); assert( PTF_LEAF == 1<<3 );
|
| + flagByte &= ~PTF_LEAF;
|
| + pPage->childPtrSize = 4-4*pPage->leaf;
|
| + pPage->xCellSize = cellSizePtr;
|
| + pBt = pPage->pBt;
|
| + if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
|
| + /* EVIDENCE-OF: R-07291-35328 A value of 5 (0x05) means the page is an
|
| + ** interior table b-tree page. */
|
| + assert( (PTF_LEAFDATA|PTF_INTKEY)==5 );
|
| + /* EVIDENCE-OF: R-26900-09176 A value of 13 (0x0d) means the page is a
|
| + ** leaf table b-tree page. */
|
| + assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 );
|
| + pPage->intKey = 1;
|
| + if( pPage->leaf ){
|
| + pPage->intKeyLeaf = 1;
|
| + pPage->xParseCell = btreeParseCellPtr;
|
| + }else{
|
| + pPage->intKeyLeaf = 0;
|
| + pPage->xCellSize = cellSizePtrNoPayload;
|
| + pPage->xParseCell = btreeParseCellPtrNoPayload;
|
| + }
|
| + pPage->maxLocal = pBt->maxLeaf;
|
| + pPage->minLocal = pBt->minLeaf;
|
| + }else if( flagByte==PTF_ZERODATA ){
|
| + /* EVIDENCE-OF: R-43316-37308 A value of 2 (0x02) means the page is an
|
| + ** interior index b-tree page. */
|
| + assert( (PTF_ZERODATA)==2 );
|
| + /* EVIDENCE-OF: R-59615-42828 A value of 10 (0x0a) means the page is a
|
| + ** leaf index b-tree page. */
|
| + assert( (PTF_ZERODATA|PTF_LEAF)==10 );
|
| + pPage->intKey = 0;
|
| + pPage->intKeyLeaf = 0;
|
| + pPage->xParseCell = btreeParseCellPtrIndex;
|
| + pPage->maxLocal = pBt->maxLocal;
|
| + pPage->minLocal = pBt->minLocal;
|
| + }else{
|
| + /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is
|
| + ** an error. */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + pPage->max1bytePayload = pBt->max1bytePayload;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Initialize the auxiliary information for a disk block.
|
| +**
|
| +** Return SQLITE_OK on success. If we see that the page does
|
| +** not contain a well-formed database page, then return
|
| +** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not
|
| +** guarantee that the page is well-formed. It only shows that
|
| +** we failed to detect any corruption.
|
| +*/
|
| +static int btreeInitPage(MemPage *pPage){
|
| +
|
| + assert( pPage->pBt!=0 );
|
| + assert( pPage->pBt->db!=0 );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
|
| + assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) );
|
| + assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) );
|
| +
|
| + if( !pPage->isInit ){
|
| + int pc; /* Address of a freeblock within pPage->aData[] */
|
| + u8 hdr; /* Offset to beginning of page header */
|
| + u8 *data; /* Equal to pPage->aData */
|
| + BtShared *pBt; /* The main btree structure */
|
| + int usableSize; /* Amount of usable space on each page */
|
| + u16 cellOffset; /* Offset from start of page to first cell pointer */
|
| + int nFree; /* Number of unused bytes on the page */
|
| + int top; /* First byte of the cell content area */
|
| + int iCellFirst; /* First allowable cell or freeblock offset */
|
| + int iCellLast; /* Last possible cell or freeblock offset */
|
| +
|
| + pBt = pPage->pBt;
|
| +
|
| + hdr = pPage->hdrOffset;
|
| + data = pPage->aData;
|
| + /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating
|
| + ** the b-tree page type. */
|
| + if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT;
|
| + assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
|
| + pPage->maskPage = (u16)(pBt->pageSize - 1);
|
| + pPage->nOverflow = 0;
|
| + usableSize = pBt->usableSize;
|
| + pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize;
|
| + pPage->aDataEnd = &data[usableSize];
|
| + pPage->aCellIdx = &data[cellOffset];
|
| + pPage->aDataOfst = &data[pPage->childPtrSize];
|
| + /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates
|
| + ** the start of the cell content area. A zero value for this integer is
|
| + ** interpreted as 65536. */
|
| + top = get2byteNotZero(&data[hdr+5]);
|
| + /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the
|
| + ** number of cells on the page. */
|
| + pPage->nCell = get2byte(&data[hdr+3]);
|
| + if( pPage->nCell>MX_CELL(pBt) ){
|
| + /* To many cells for a single page. The page must be corrupt */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + testcase( pPage->nCell==MX_CELL(pBt) );
|
| + /* EVIDENCE-OF: R-24089-57979 If a page contains no cells (which is only
|
| + ** possible for a root page of a table that contains no rows) then the
|
| + ** offset to the cell content area will equal the page size minus the
|
| + ** bytes of reserved space. */
|
| + assert( pPage->nCell>0 || top==usableSize || CORRUPT_DB );
|
| +
|
| + /* A malformed database page might cause us to read past the end
|
| + ** of page when parsing a cell.
|
| + **
|
| + ** The following block of code checks early to see if a cell extends
|
| + ** past the end of a page boundary and causes SQLITE_CORRUPT to be
|
| + ** returned if it does.
|
| + */
|
| + iCellFirst = cellOffset + 2*pPage->nCell;
|
| + iCellLast = usableSize - 4;
|
| + if( pBt->db->flags & SQLITE_CellSizeCk ){
|
| + int i; /* Index into the cell pointer array */
|
| + int sz; /* Size of a cell */
|
| +
|
| + if( !pPage->leaf ) iCellLast--;
|
| + for(i=0; i<pPage->nCell; i++){
|
| + pc = get2byteAligned(&data[cellOffset+i*2]);
|
| + testcase( pc==iCellFirst );
|
| + testcase( pc==iCellLast );
|
| + if( pc<iCellFirst || pc>iCellLast ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + sz = pPage->xCellSize(pPage, &data[pc]);
|
| + testcase( pc+sz==usableSize );
|
| + if( pc+sz>usableSize ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + }
|
| + if( !pPage->leaf ) iCellLast++;
|
| + }
|
| +
|
| + /* Compute the total free space on the page
|
| + ** EVIDENCE-OF: R-23588-34450 The two-byte integer at offset 1 gives the
|
| + ** start of the first freeblock on the page, or is zero if there are no
|
| + ** freeblocks. */
|
| + pc = get2byte(&data[hdr+1]);
|
| + nFree = data[hdr+7] + top; /* Init nFree to non-freeblock free space */
|
| + if( pc>0 ){
|
| + u32 next, size;
|
| + if( pc<iCellFirst ){
|
| + /* EVIDENCE-OF: R-55530-52930 In a well-formed b-tree page, there will
|
| + ** always be at least one cell before the first freeblock.
|
| + */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + while( 1 ){
|
| + if( pc>iCellLast ){
|
| + return SQLITE_CORRUPT_BKPT; /* Freeblock off the end of the page */
|
| + }
|
| + next = get2byte(&data[pc]);
|
| + size = get2byte(&data[pc+2]);
|
| + nFree = nFree + size;
|
| + if( next<=pc+size+3 ) break;
|
| + pc = next;
|
| + }
|
| + if( next>0 ){
|
| + return SQLITE_CORRUPT_BKPT; /* Freeblock not in ascending order */
|
| + }
|
| + if( pc+size>(unsigned int)usableSize ){
|
| + return SQLITE_CORRUPT_BKPT; /* Last freeblock extends past page end */
|
| + }
|
| + }
|
| +
|
| + /* At this point, nFree contains the sum of the offset to the start
|
| + ** of the cell-content area plus the number of free bytes within
|
| + ** the cell-content area. If this is greater than the usable-size
|
| + ** of the page, then the page must be corrupted. This check also
|
| + ** serves to verify that the offset to the start of the cell-content
|
| + ** area, according to the page header, lies within the page.
|
| + */
|
| + if( nFree>usableSize ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + pPage->nFree = (u16)(nFree - iCellFirst);
|
| + pPage->isInit = 1;
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Set up a raw page so that it looks like a database page holding
|
| +** no entries.
|
| +*/
|
| +static void zeroPage(MemPage *pPage, int flags){
|
| + unsigned char *data = pPage->aData;
|
| + BtShared *pBt = pPage->pBt;
|
| + u8 hdr = pPage->hdrOffset;
|
| + u16 first;
|
| +
|
| + assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
|
| + assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
|
| + assert( sqlite3PagerGetData(pPage->pDbPage) == data );
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + if( pBt->btsFlags & BTS_SECURE_DELETE ){
|
| + memset(&data[hdr], 0, pBt->usableSize - hdr);
|
| + }
|
| + data[hdr] = (char)flags;
|
| + first = hdr + ((flags&PTF_LEAF)==0 ? 12 : 8);
|
| + memset(&data[hdr+1], 0, 4);
|
| + data[hdr+7] = 0;
|
| + put2byte(&data[hdr+5], pBt->usableSize);
|
| + pPage->nFree = (u16)(pBt->usableSize - first);
|
| + decodeFlags(pPage, flags);
|
| + pPage->cellOffset = first;
|
| + pPage->aDataEnd = &data[pBt->usableSize];
|
| + pPage->aCellIdx = &data[first];
|
| + pPage->aDataOfst = &data[pPage->childPtrSize];
|
| + pPage->nOverflow = 0;
|
| + assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
|
| + pPage->maskPage = (u16)(pBt->pageSize - 1);
|
| + pPage->nCell = 0;
|
| + pPage->isInit = 1;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Convert a DbPage obtained from the pager into a MemPage used by
|
| +** the btree layer.
|
| +*/
|
| +static MemPage *btreePageFromDbPage(DbPage *pDbPage, Pgno pgno, BtShared *pBt){
|
| + MemPage *pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
|
| + if( pgno!=pPage->pgno ){
|
| + pPage->aData = sqlite3PagerGetData(pDbPage);
|
| + pPage->pDbPage = pDbPage;
|
| + pPage->pBt = pBt;
|
| + pPage->pgno = pgno;
|
| + pPage->hdrOffset = pgno==1 ? 100 : 0;
|
| + }
|
| + assert( pPage->aData==sqlite3PagerGetData(pDbPage) );
|
| + return pPage;
|
| +}
|
| +
|
| +/*
|
| +** Get a page from the pager. Initialize the MemPage.pBt and
|
| +** MemPage.aData elements if needed. See also: btreeGetUnusedPage().
|
| +**
|
| +** If the PAGER_GET_NOCONTENT flag is set, it means that we do not care
|
| +** about the content of the page at this time. So do not go to the disk
|
| +** to fetch the content. Just fill in the content with zeros for now.
|
| +** If in the future we call sqlite3PagerWrite() on this page, that
|
| +** means we have started to be concerned about content and the disk
|
| +** read should occur at that point.
|
| +*/
|
| +static int btreeGetPage(
|
| + BtShared *pBt, /* The btree */
|
| + Pgno pgno, /* Number of the page to fetch */
|
| + MemPage **ppPage, /* Return the page in this parameter */
|
| + int flags /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */
|
| +){
|
| + int rc;
|
| + DbPage *pDbPage;
|
| +
|
| + assert( flags==0 || flags==PAGER_GET_NOCONTENT || flags==PAGER_GET_READONLY );
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, flags);
|
| + if( rc ) return rc;
|
| + *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Retrieve a page from the pager cache. If the requested page is not
|
| +** already in the pager cache return NULL. Initialize the MemPage.pBt and
|
| +** MemPage.aData elements if needed.
|
| +*/
|
| +static MemPage *btreePageLookup(BtShared *pBt, Pgno pgno){
|
| + DbPage *pDbPage;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
|
| + if( pDbPage ){
|
| + return btreePageFromDbPage(pDbPage, pgno, pBt);
|
| + }
|
| + return 0;
|
| +}
|
| +
|
| +/*
|
| +** Return the size of the database file in pages. If there is any kind of
|
| +** error, return ((unsigned int)-1).
|
| +*/
|
| +static Pgno btreePagecount(BtShared *pBt){
|
| + return pBt->nPage;
|
| +}
|
| +u32 sqlite3BtreeLastPage(Btree *p){
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( ((p->pBt->nPage)&0x8000000)==0 );
|
| + return btreePagecount(p->pBt);
|
| +}
|
| +
|
| +/*
|
| +** Get a page from the pager and initialize it.
|
| +**
|
| +** If pCur!=0 then the page is being fetched as part of a moveToChild()
|
| +** call. Do additional sanity checking on the page in this case.
|
| +** And if the fetch fails, this routine must decrement pCur->iPage.
|
| +**
|
| +** The page is fetched as read-write unless pCur is not NULL and is
|
| +** a read-only cursor.
|
| +**
|
| +** If an error occurs, then *ppPage is undefined. It
|
| +** may remain unchanged, or it may be set to an invalid value.
|
| +*/
|
| +static int getAndInitPage(
|
| + BtShared *pBt, /* The database file */
|
| + Pgno pgno, /* Number of the page to get */
|
| + MemPage **ppPage, /* Write the page pointer here */
|
| + BtCursor *pCur, /* Cursor to receive the page, or NULL */
|
| + int bReadOnly /* True for a read-only page */
|
| +){
|
| + int rc;
|
| + DbPage *pDbPage;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( pCur==0 || ppPage==&pCur->apPage[pCur->iPage] );
|
| + assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
|
| + assert( pCur==0 || pCur->iPage>0 );
|
| +
|
| + if( pgno>btreePagecount(pBt) ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto getAndInitPage_error;
|
| + }
|
| + rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly);
|
| + if( rc ){
|
| + goto getAndInitPage_error;
|
| + }
|
| + *ppPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
|
| + if( (*ppPage)->isInit==0 ){
|
| + btreePageFromDbPage(pDbPage, pgno, pBt);
|
| + rc = btreeInitPage(*ppPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(*ppPage);
|
| + goto getAndInitPage_error;
|
| + }
|
| + }
|
| + assert( (*ppPage)->pgno==pgno );
|
| + assert( (*ppPage)->aData==sqlite3PagerGetData(pDbPage) );
|
| +
|
| + /* If obtaining a child page for a cursor, we must verify that the page is
|
| + ** compatible with the root page. */
|
| + if( pCur && ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->curIntKey) ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + releasePage(*ppPage);
|
| + goto getAndInitPage_error;
|
| + }
|
| + return SQLITE_OK;
|
| +
|
| +getAndInitPage_error:
|
| + if( pCur ) pCur->iPage--;
|
| + testcase( pgno==0 );
|
| + assert( pgno!=0 || rc==SQLITE_CORRUPT );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Release a MemPage. This should be called once for each prior
|
| +** call to btreeGetPage.
|
| +*/
|
| +static void releasePageNotNull(MemPage *pPage){
|
| + assert( pPage->aData );
|
| + assert( pPage->pBt );
|
| + assert( pPage->pDbPage!=0 );
|
| + assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
|
| + assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + sqlite3PagerUnrefNotNull(pPage->pDbPage);
|
| +}
|
| +static void releasePage(MemPage *pPage){
|
| + if( pPage ) releasePageNotNull(pPage);
|
| +}
|
| +
|
| +/*
|
| +** Get an unused page.
|
| +**
|
| +** This works just like btreeGetPage() with the addition:
|
| +**
|
| +** * If the page is already in use for some other purpose, immediately
|
| +** release it and return an SQLITE_CURRUPT error.
|
| +** * Make sure the isInit flag is clear
|
| +*/
|
| +static int btreeGetUnusedPage(
|
| + BtShared *pBt, /* The btree */
|
| + Pgno pgno, /* Number of the page to fetch */
|
| + MemPage **ppPage, /* Return the page in this parameter */
|
| + int flags /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */
|
| +){
|
| + int rc = btreeGetPage(pBt, pgno, ppPage, flags);
|
| + if( rc==SQLITE_OK ){
|
| + if( sqlite3PagerPageRefcount((*ppPage)->pDbPage)>1 ){
|
| + releasePage(*ppPage);
|
| + *ppPage = 0;
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + (*ppPage)->isInit = 0;
|
| + }else{
|
| + *ppPage = 0;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** During a rollback, when the pager reloads information into the cache
|
| +** so that the cache is restored to its original state at the start of
|
| +** the transaction, for each page restored this routine is called.
|
| +**
|
| +** This routine needs to reset the extra data section at the end of the
|
| +** page to agree with the restored data.
|
| +*/
|
| +static void pageReinit(DbPage *pData){
|
| + MemPage *pPage;
|
| + pPage = (MemPage *)sqlite3PagerGetExtra(pData);
|
| + assert( sqlite3PagerPageRefcount(pData)>0 );
|
| + if( pPage->isInit ){
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + pPage->isInit = 0;
|
| + if( sqlite3PagerPageRefcount(pData)>1 ){
|
| + /* pPage might not be a btree page; it might be an overflow page
|
| + ** or ptrmap page or a free page. In those cases, the following
|
| + ** call to btreeInitPage() will likely return SQLITE_CORRUPT.
|
| + ** But no harm is done by this. And it is very important that
|
| + ** btreeInitPage() be called on every btree page so we make
|
| + ** the call for every page that comes in for re-initing. */
|
| + btreeInitPage(pPage);
|
| + }
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Invoke the busy handler for a btree.
|
| +*/
|
| +static int btreeInvokeBusyHandler(void *pArg){
|
| + BtShared *pBt = (BtShared*)pArg;
|
| + assert( pBt->db );
|
| + assert( sqlite3_mutex_held(pBt->db->mutex) );
|
| + return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
|
| +}
|
| +
|
| +/*
|
| +** Open a database file.
|
| +**
|
| +** zFilename is the name of the database file. If zFilename is NULL
|
| +** then an ephemeral database is created. The ephemeral database might
|
| +** be exclusively in memory, or it might use a disk-based memory cache.
|
| +** Either way, the ephemeral database will be automatically deleted
|
| +** when sqlite3BtreeClose() is called.
|
| +**
|
| +** If zFilename is ":memory:" then an in-memory database is created
|
| +** that is automatically destroyed when it is closed.
|
| +**
|
| +** The "flags" parameter is a bitmask that might contain bits like
|
| +** BTREE_OMIT_JOURNAL and/or BTREE_MEMORY.
|
| +**
|
| +** If the database is already opened in the same database connection
|
| +** and we are in shared cache mode, then the open will fail with an
|
| +** SQLITE_CONSTRAINT error. We cannot allow two or more BtShared
|
| +** objects in the same database connection since doing so will lead
|
| +** to problems with locking.
|
| +*/
|
| +int sqlite3BtreeOpen(
|
| + sqlite3_vfs *pVfs, /* VFS to use for this b-tree */
|
| + const char *zFilename, /* Name of the file containing the BTree database */
|
| + sqlite3 *db, /* Associated database handle */
|
| + Btree **ppBtree, /* Pointer to new Btree object written here */
|
| + int flags, /* Options */
|
| + int vfsFlags /* Flags passed through to sqlite3_vfs.xOpen() */
|
| +){
|
| + BtShared *pBt = 0; /* Shared part of btree structure */
|
| + Btree *p; /* Handle to return */
|
| + sqlite3_mutex *mutexOpen = 0; /* Prevents a race condition. Ticket #3537 */
|
| + int rc = SQLITE_OK; /* Result code from this function */
|
| + u8 nReserve; /* Byte of unused space on each page */
|
| + unsigned char zDbHeader[100]; /* Database header content */
|
| +
|
| + /* True if opening an ephemeral, temporary database */
|
| + const int isTempDb = zFilename==0 || zFilename[0]==0;
|
| +
|
| + /* Set the variable isMemdb to true for an in-memory database, or
|
| + ** false for a file-based database.
|
| + */
|
| +#ifdef SQLITE_OMIT_MEMORYDB
|
| + const int isMemdb = 0;
|
| +#else
|
| + const int isMemdb = (zFilename && strcmp(zFilename, ":memory:")==0)
|
| + || (isTempDb && sqlite3TempInMemory(db))
|
| + || (vfsFlags & SQLITE_OPEN_MEMORY)!=0;
|
| +#endif
|
| +
|
| + assert( db!=0 );
|
| + assert( pVfs!=0 );
|
| + assert( sqlite3_mutex_held(db->mutex) );
|
| + assert( (flags&0xff)==flags ); /* flags fit in 8 bits */
|
| +
|
| + /* Only a BTREE_SINGLE database can be BTREE_UNORDERED */
|
| + assert( (flags & BTREE_UNORDERED)==0 || (flags & BTREE_SINGLE)!=0 );
|
| +
|
| + /* A BTREE_SINGLE database is always a temporary and/or ephemeral */
|
| + assert( (flags & BTREE_SINGLE)==0 || isTempDb );
|
| +
|
| + if( isMemdb ){
|
| + flags |= BTREE_MEMORY;
|
| + }
|
| + if( (vfsFlags & SQLITE_OPEN_MAIN_DB)!=0 && (isMemdb || isTempDb) ){
|
| + vfsFlags = (vfsFlags & ~SQLITE_OPEN_MAIN_DB) | SQLITE_OPEN_TEMP_DB;
|
| + }
|
| + p = sqlite3MallocZero(sizeof(Btree));
|
| + if( !p ){
|
| + return SQLITE_NOMEM_BKPT;
|
| + }
|
| + p->inTrans = TRANS_NONE;
|
| + p->db = db;
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + p->lock.pBtree = p;
|
| + p->lock.iTable = 1;
|
| +#endif
|
| +
|
| +#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
|
| + /*
|
| + ** If this Btree is a candidate for shared cache, try to find an
|
| + ** existing BtShared object that we can share with
|
| + */
|
| + if( isTempDb==0 && (isMemdb==0 || (vfsFlags&SQLITE_OPEN_URI)!=0) ){
|
| + if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){
|
| + int nFilename = sqlite3Strlen30(zFilename)+1;
|
| + int nFullPathname = pVfs->mxPathname+1;
|
| + char *zFullPathname = sqlite3Malloc(MAX(nFullPathname,nFilename));
|
| + MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
|
| +
|
| + p->sharable = 1;
|
| + if( !zFullPathname ){
|
| + sqlite3_free(p);
|
| + return SQLITE_NOMEM_BKPT;
|
| + }
|
| + if( isMemdb ){
|
| + memcpy(zFullPathname, zFilename, nFilename);
|
| + }else{
|
| + rc = sqlite3OsFullPathname(pVfs, zFilename,
|
| + nFullPathname, zFullPathname);
|
| + if( rc ){
|
| + sqlite3_free(zFullPathname);
|
| + sqlite3_free(p);
|
| + return rc;
|
| + }
|
| + }
|
| +#if SQLITE_THREADSAFE
|
| + mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN);
|
| + sqlite3_mutex_enter(mutexOpen);
|
| + mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
|
| + sqlite3_mutex_enter(mutexShared);
|
| +#endif
|
| + for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){
|
| + assert( pBt->nRef>0 );
|
| + if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager, 0))
|
| + && sqlite3PagerVfs(pBt->pPager)==pVfs ){
|
| + int iDb;
|
| + for(iDb=db->nDb-1; iDb>=0; iDb--){
|
| + Btree *pExisting = db->aDb[iDb].pBt;
|
| + if( pExisting && pExisting->pBt==pBt ){
|
| + sqlite3_mutex_leave(mutexShared);
|
| + sqlite3_mutex_leave(mutexOpen);
|
| + sqlite3_free(zFullPathname);
|
| + sqlite3_free(p);
|
| + return SQLITE_CONSTRAINT;
|
| + }
|
| + }
|
| + p->pBt = pBt;
|
| + pBt->nRef++;
|
| + break;
|
| + }
|
| + }
|
| + sqlite3_mutex_leave(mutexShared);
|
| + sqlite3_free(zFullPathname);
|
| + }
|
| +#ifdef SQLITE_DEBUG
|
| + else{
|
| + /* In debug mode, we mark all persistent databases as sharable
|
| + ** even when they are not. This exercises the locking code and
|
| + ** gives more opportunity for asserts(sqlite3_mutex_held())
|
| + ** statements to find locking problems.
|
| + */
|
| + p->sharable = 1;
|
| + }
|
| +#endif
|
| + }
|
| +#endif
|
| + if( pBt==0 ){
|
| + /*
|
| + ** The following asserts make sure that structures used by the btree are
|
| + ** the right size. This is to guard against size changes that result
|
| + ** when compiling on a different architecture.
|
| + */
|
| + assert( sizeof(i64)==8 );
|
| + assert( sizeof(u64)==8 );
|
| + assert( sizeof(u32)==4 );
|
| + assert( sizeof(u16)==2 );
|
| + assert( sizeof(Pgno)==4 );
|
| +
|
| + pBt = sqlite3MallocZero( sizeof(*pBt) );
|
| + if( pBt==0 ){
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + goto btree_open_out;
|
| + }
|
| + rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
|
| + sizeof(MemPage), flags, vfsFlags, pageReinit);
|
| + if( rc==SQLITE_OK ){
|
| + sqlite3PagerSetMmapLimit(pBt->pPager, db->szMmap);
|
| + rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
|
| + }
|
| + if( rc!=SQLITE_OK ){
|
| + goto btree_open_out;
|
| + }
|
| + pBt->openFlags = (u8)flags;
|
| + pBt->db = db;
|
| + sqlite3PagerSetBusyhandler(pBt->pPager, btreeInvokeBusyHandler, pBt);
|
| + p->pBt = pBt;
|
| +
|
| + pBt->pCursor = 0;
|
| + pBt->pPage1 = 0;
|
| + if( sqlite3PagerIsreadonly(pBt->pPager) ) pBt->btsFlags |= BTS_READ_ONLY;
|
| +#ifdef SQLITE_SECURE_DELETE
|
| + pBt->btsFlags |= BTS_SECURE_DELETE;
|
| +#endif
|
| + /* EVIDENCE-OF: R-51873-39618 The page size for a database file is
|
| + ** determined by the 2-byte integer located at an offset of 16 bytes from
|
| + ** the beginning of the database file. */
|
| + pBt->pageSize = (zDbHeader[16]<<8) | (zDbHeader[17]<<16);
|
| + if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
|
| + || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
|
| + pBt->pageSize = 0;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + /* If the magic name ":memory:" will create an in-memory database, then
|
| + ** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
|
| + ** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
|
| + ** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
|
| + ** regular file-name. In this case the auto-vacuum applies as per normal.
|
| + */
|
| + if( zFilename && !isMemdb ){
|
| + pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
|
| + pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
|
| + }
|
| +#endif
|
| + nReserve = 0;
|
| + }else{
|
| + /* EVIDENCE-OF: R-37497-42412 The size of the reserved region is
|
| + ** determined by the one-byte unsigned integer found at an offset of 20
|
| + ** into the database file header. */
|
| + nReserve = zDbHeader[20];
|
| + pBt->btsFlags |= BTS_PAGESIZE_FIXED;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
|
| + pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
|
| +#endif
|
| + }
|
| + rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
|
| + if( rc ) goto btree_open_out;
|
| + pBt->usableSize = pBt->pageSize - nReserve;
|
| + assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */
|
| +
|
| +#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
|
| + /* Add the new BtShared object to the linked list sharable BtShareds.
|
| + */
|
| + pBt->nRef = 1;
|
| + if( p->sharable ){
|
| + MUTEX_LOGIC( sqlite3_mutex *mutexShared; )
|
| + MUTEX_LOGIC( mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);)
|
| + if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){
|
| + pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST);
|
| + if( pBt->mutex==0 ){
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + goto btree_open_out;
|
| + }
|
| + }
|
| + sqlite3_mutex_enter(mutexShared);
|
| + pBt->pNext = GLOBAL(BtShared*,sqlite3SharedCacheList);
|
| + GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt;
|
| + sqlite3_mutex_leave(mutexShared);
|
| + }
|
| +#endif
|
| + }
|
| +
|
| +#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
|
| + /* If the new Btree uses a sharable pBtShared, then link the new
|
| + ** Btree into the list of all sharable Btrees for the same connection.
|
| + ** The list is kept in ascending order by pBt address.
|
| + */
|
| + if( p->sharable ){
|
| + int i;
|
| + Btree *pSib;
|
| + for(i=0; i<db->nDb; i++){
|
| + if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){
|
| + while( pSib->pPrev ){ pSib = pSib->pPrev; }
|
| + if( (uptr)p->pBt<(uptr)pSib->pBt ){
|
| + p->pNext = pSib;
|
| + p->pPrev = 0;
|
| + pSib->pPrev = p;
|
| + }else{
|
| + while( pSib->pNext && (uptr)pSib->pNext->pBt<(uptr)p->pBt ){
|
| + pSib = pSib->pNext;
|
| + }
|
| + p->pNext = pSib->pNext;
|
| + p->pPrev = pSib;
|
| + if( p->pNext ){
|
| + p->pNext->pPrev = p;
|
| + }
|
| + pSib->pNext = p;
|
| + }
|
| + break;
|
| + }
|
| + }
|
| + }
|
| +#endif
|
| + *ppBtree = p;
|
| +
|
| +btree_open_out:
|
| + if( rc!=SQLITE_OK ){
|
| + if( pBt && pBt->pPager ){
|
| + sqlite3PagerClose(pBt->pPager, 0);
|
| + }
|
| + sqlite3_free(pBt);
|
| + sqlite3_free(p);
|
| + *ppBtree = 0;
|
| + }else{
|
| + sqlite3_file *pFile;
|
| +
|
| + /* If the B-Tree was successfully opened, set the pager-cache size to the
|
| + ** default value. Except, when opening on an existing shared pager-cache,
|
| + ** do not change the pager-cache size.
|
| + */
|
| + if( sqlite3BtreeSchema(p, 0, 0)==0 ){
|
| + sqlite3PagerSetCachesize(p->pBt->pPager, SQLITE_DEFAULT_CACHE_SIZE);
|
| + }
|
| +
|
| + pFile = sqlite3PagerFile(pBt->pPager);
|
| + if( pFile->pMethods ){
|
| + sqlite3OsFileControlHint(pFile, SQLITE_FCNTL_PDB, (void*)&pBt->db);
|
| + }
|
| + }
|
| + if( mutexOpen ){
|
| + assert( sqlite3_mutex_held(mutexOpen) );
|
| + sqlite3_mutex_leave(mutexOpen);
|
| + }
|
| + assert( rc!=SQLITE_OK || sqlite3BtreeConnectionCount(*ppBtree)>0 );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Decrement the BtShared.nRef counter. When it reaches zero,
|
| +** remove the BtShared structure from the sharing list. Return
|
| +** true if the BtShared.nRef counter reaches zero and return
|
| +** false if it is still positive.
|
| +*/
|
| +static int removeFromSharingList(BtShared *pBt){
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + MUTEX_LOGIC( sqlite3_mutex *pMaster; )
|
| + BtShared *pList;
|
| + int removed = 0;
|
| +
|
| + assert( sqlite3_mutex_notheld(pBt->mutex) );
|
| + MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
|
| + sqlite3_mutex_enter(pMaster);
|
| + pBt->nRef--;
|
| + if( pBt->nRef<=0 ){
|
| + if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){
|
| + GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext;
|
| + }else{
|
| + pList = GLOBAL(BtShared*,sqlite3SharedCacheList);
|
| + while( ALWAYS(pList) && pList->pNext!=pBt ){
|
| + pList=pList->pNext;
|
| + }
|
| + if( ALWAYS(pList) ){
|
| + pList->pNext = pBt->pNext;
|
| + }
|
| + }
|
| + if( SQLITE_THREADSAFE ){
|
| + sqlite3_mutex_free(pBt->mutex);
|
| + }
|
| + removed = 1;
|
| + }
|
| + sqlite3_mutex_leave(pMaster);
|
| + return removed;
|
| +#else
|
| + return 1;
|
| +#endif
|
| +}
|
| +
|
| +/*
|
| +** Make sure pBt->pTmpSpace points to an allocation of
|
| +** MX_CELL_SIZE(pBt) bytes with a 4-byte prefix for a left-child
|
| +** pointer.
|
| +*/
|
| +static void allocateTempSpace(BtShared *pBt){
|
| + if( !pBt->pTmpSpace ){
|
| + pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize );
|
| +
|
| + /* One of the uses of pBt->pTmpSpace is to format cells before
|
| + ** inserting them into a leaf page (function fillInCell()). If
|
| + ** a cell is less than 4 bytes in size, it is rounded up to 4 bytes
|
| + ** by the various routines that manipulate binary cells. Which
|
| + ** can mean that fillInCell() only initializes the first 2 or 3
|
| + ** bytes of pTmpSpace, but that the first 4 bytes are copied from
|
| + ** it into a database page. This is not actually a problem, but it
|
| + ** does cause a valgrind error when the 1 or 2 bytes of unitialized
|
| + ** data is passed to system call write(). So to avoid this error,
|
| + ** zero the first 4 bytes of temp space here.
|
| + **
|
| + ** Also: Provide four bytes of initialized space before the
|
| + ** beginning of pTmpSpace as an area available to prepend the
|
| + ** left-child pointer to the beginning of a cell.
|
| + */
|
| + if( pBt->pTmpSpace ){
|
| + memset(pBt->pTmpSpace, 0, 8);
|
| + pBt->pTmpSpace += 4;
|
| + }
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Free the pBt->pTmpSpace allocation
|
| +*/
|
| +static void freeTempSpace(BtShared *pBt){
|
| + if( pBt->pTmpSpace ){
|
| + pBt->pTmpSpace -= 4;
|
| + sqlite3PageFree(pBt->pTmpSpace);
|
| + pBt->pTmpSpace = 0;
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Close an open database and invalidate all cursors.
|
| +*/
|
| +int sqlite3BtreeClose(Btree *p){
|
| + BtShared *pBt = p->pBt;
|
| + BtCursor *pCur;
|
| +
|
| + /* Close all cursors opened via this handle. */
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + pCur = pBt->pCursor;
|
| + while( pCur ){
|
| + BtCursor *pTmp = pCur;
|
| + pCur = pCur->pNext;
|
| + if( pTmp->pBtree==p ){
|
| + sqlite3BtreeCloseCursor(pTmp);
|
| + }
|
| + }
|
| +
|
| + /* Rollback any active transaction and free the handle structure.
|
| + ** The call to sqlite3BtreeRollback() drops any table-locks held by
|
| + ** this handle.
|
| + */
|
| + sqlite3BtreeRollback(p, SQLITE_OK, 0);
|
| + sqlite3BtreeLeave(p);
|
| +
|
| + /* If there are still other outstanding references to the shared-btree
|
| + ** structure, return now. The remainder of this procedure cleans
|
| + ** up the shared-btree.
|
| + */
|
| + assert( p->wantToLock==0 && p->locked==0 );
|
| + if( !p->sharable || removeFromSharingList(pBt) ){
|
| + /* The pBt is no longer on the sharing list, so we can access
|
| + ** it without having to hold the mutex.
|
| + **
|
| + ** Clean out and delete the BtShared object.
|
| + */
|
| + assert( !pBt->pCursor );
|
| + sqlite3PagerClose(pBt->pPager, p->db);
|
| + if( pBt->xFreeSchema && pBt->pSchema ){
|
| + pBt->xFreeSchema(pBt->pSchema);
|
| + }
|
| + sqlite3DbFree(0, pBt->pSchema);
|
| + freeTempSpace(pBt);
|
| + sqlite3_free(pBt);
|
| + }
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + assert( p->wantToLock==0 );
|
| + assert( p->locked==0 );
|
| + if( p->pPrev ) p->pPrev->pNext = p->pNext;
|
| + if( p->pNext ) p->pNext->pPrev = p->pPrev;
|
| +#endif
|
| +
|
| + sqlite3_free(p);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Change the "soft" limit on the number of pages in the cache.
|
| +** Unused and unmodified pages will be recycled when the number of
|
| +** pages in the cache exceeds this soft limit. But the size of the
|
| +** cache is allowed to grow larger than this limit if it contains
|
| +** dirty pages or pages still in active use.
|
| +*/
|
| +int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
|
| + BtShared *pBt = p->pBt;
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + sqlite3PagerSetCachesize(pBt->pPager, mxPage);
|
| + sqlite3BtreeLeave(p);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Change the "spill" limit on the number of pages in the cache.
|
| +** If the number of pages exceeds this limit during a write transaction,
|
| +** the pager might attempt to "spill" pages to the journal early in
|
| +** order to free up memory.
|
| +**
|
| +** The value returned is the current spill size. If zero is passed
|
| +** as an argument, no changes are made to the spill size setting, so
|
| +** using mxPage of 0 is a way to query the current spill size.
|
| +*/
|
| +int sqlite3BtreeSetSpillSize(Btree *p, int mxPage){
|
| + BtShared *pBt = p->pBt;
|
| + int res;
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + res = sqlite3PagerSetSpillsize(pBt->pPager, mxPage);
|
| + sqlite3BtreeLeave(p);
|
| + return res;
|
| +}
|
| +
|
| +#if SQLITE_MAX_MMAP_SIZE>0
|
| +/*
|
| +** Change the limit on the amount of the database file that may be
|
| +** memory mapped.
|
| +*/
|
| +int sqlite3BtreeSetMmapLimit(Btree *p, sqlite3_int64 szMmap){
|
| + BtShared *pBt = p->pBt;
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + sqlite3PagerSetMmapLimit(pBt->pPager, szMmap);
|
| + sqlite3BtreeLeave(p);
|
| + return SQLITE_OK;
|
| +}
|
| +#endif /* SQLITE_MAX_MMAP_SIZE>0 */
|
| +
|
| +/*
|
| +** Change the way data is synced to disk in order to increase or decrease
|
| +** how well the database resists damage due to OS crashes and power
|
| +** failures. Level 1 is the same as asynchronous (no syncs() occur and
|
| +** there is a high probability of damage) Level 2 is the default. There
|
| +** is a very low but non-zero probability of damage. Level 3 reduces the
|
| +** probability of damage to near zero but with a write performance reduction.
|
| +*/
|
| +#ifndef SQLITE_OMIT_PAGER_PRAGMAS
|
| +int sqlite3BtreeSetPagerFlags(
|
| + Btree *p, /* The btree to set the safety level on */
|
| + unsigned pgFlags /* Various PAGER_* flags */
|
| +){
|
| + BtShared *pBt = p->pBt;
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + sqlite3PagerSetFlags(pBt->pPager, pgFlags);
|
| + sqlite3BtreeLeave(p);
|
| + return SQLITE_OK;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Change the default pages size and the number of reserved bytes per page.
|
| +** Or, if the page size has already been fixed, return SQLITE_READONLY
|
| +** without changing anything.
|
| +**
|
| +** The page size must be a power of 2 between 512 and 65536. If the page
|
| +** size supplied does not meet this constraint then the page size is not
|
| +** changed.
|
| +**
|
| +** Page sizes are constrained to be a power of two so that the region
|
| +** of the database file used for locking (beginning at PENDING_BYTE,
|
| +** the first byte past the 1GB boundary, 0x40000000) needs to occur
|
| +** at the beginning of a page.
|
| +**
|
| +** If parameter nReserve is less than zero, then the number of reserved
|
| +** bytes per page is left unchanged.
|
| +**
|
| +** If the iFix!=0 then the BTS_PAGESIZE_FIXED flag is set so that the page size
|
| +** and autovacuum mode can no longer be changed.
|
| +*/
|
| +int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
|
| + int rc = SQLITE_OK;
|
| + BtShared *pBt = p->pBt;
|
| + assert( nReserve>=-1 && nReserve<=255 );
|
| + sqlite3BtreeEnter(p);
|
| +#if SQLITE_HAS_CODEC
|
| + if( nReserve>pBt->optimalReserve ) pBt->optimalReserve = (u8)nReserve;
|
| +#endif
|
| + if( pBt->btsFlags & BTS_PAGESIZE_FIXED ){
|
| + sqlite3BtreeLeave(p);
|
| + return SQLITE_READONLY;
|
| + }
|
| + if( nReserve<0 ){
|
| + nReserve = pBt->pageSize - pBt->usableSize;
|
| + }
|
| + assert( nReserve>=0 && nReserve<=255 );
|
| + if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
|
| + ((pageSize-1)&pageSize)==0 ){
|
| + assert( (pageSize & 7)==0 );
|
| + assert( !pBt->pCursor );
|
| + pBt->pageSize = (u32)pageSize;
|
| + freeTempSpace(pBt);
|
| + }
|
| + rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
|
| + pBt->usableSize = pBt->pageSize - (u16)nReserve;
|
| + if( iFix ) pBt->btsFlags |= BTS_PAGESIZE_FIXED;
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return the currently defined page size
|
| +*/
|
| +int sqlite3BtreeGetPageSize(Btree *p){
|
| + return p->pBt->pageSize;
|
| +}
|
| +
|
| +/*
|
| +** This function is similar to sqlite3BtreeGetReserve(), except that it
|
| +** may only be called if it is guaranteed that the b-tree mutex is already
|
| +** held.
|
| +**
|
| +** This is useful in one special case in the backup API code where it is
|
| +** known that the shared b-tree mutex is held, but the mutex on the
|
| +** database handle that owns *p is not. In this case if sqlite3BtreeEnter()
|
| +** were to be called, it might collide with some other operation on the
|
| +** database handle that owns *p, causing undefined behavior.
|
| +*/
|
| +int sqlite3BtreeGetReserveNoMutex(Btree *p){
|
| + int n;
|
| + assert( sqlite3_mutex_held(p->pBt->mutex) );
|
| + n = p->pBt->pageSize - p->pBt->usableSize;
|
| + return n;
|
| +}
|
| +
|
| +/*
|
| +** Return the number of bytes of space at the end of every page that
|
| +** are intentually left unused. This is the "reserved" space that is
|
| +** sometimes used by extensions.
|
| +**
|
| +** If SQLITE_HAS_MUTEX is defined then the number returned is the
|
| +** greater of the current reserved space and the maximum requested
|
| +** reserve space.
|
| +*/
|
| +int sqlite3BtreeGetOptimalReserve(Btree *p){
|
| + int n;
|
| + sqlite3BtreeEnter(p);
|
| + n = sqlite3BtreeGetReserveNoMutex(p);
|
| +#ifdef SQLITE_HAS_CODEC
|
| + if( n<p->pBt->optimalReserve ) n = p->pBt->optimalReserve;
|
| +#endif
|
| + sqlite3BtreeLeave(p);
|
| + return n;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Set the maximum page count for a database if mxPage is positive.
|
| +** No changes are made if mxPage is 0 or negative.
|
| +** Regardless of the value of mxPage, return the maximum page count.
|
| +*/
|
| +int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
|
| + int n;
|
| + sqlite3BtreeEnter(p);
|
| + n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);
|
| + sqlite3BtreeLeave(p);
|
| + return n;
|
| +}
|
| +
|
| +/*
|
| +** Set the BTS_SECURE_DELETE flag if newFlag is 0 or 1. If newFlag is -1,
|
| +** then make no changes. Always return the value of the BTS_SECURE_DELETE
|
| +** setting after the change.
|
| +*/
|
| +int sqlite3BtreeSecureDelete(Btree *p, int newFlag){
|
| + int b;
|
| + if( p==0 ) return 0;
|
| + sqlite3BtreeEnter(p);
|
| + if( newFlag>=0 ){
|
| + p->pBt->btsFlags &= ~BTS_SECURE_DELETE;
|
| + if( newFlag ) p->pBt->btsFlags |= BTS_SECURE_DELETE;
|
| + }
|
| + b = (p->pBt->btsFlags & BTS_SECURE_DELETE)!=0;
|
| + sqlite3BtreeLeave(p);
|
| + return b;
|
| +}
|
| +
|
| +/*
|
| +** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
|
| +** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
|
| +** is disabled. The default value for the auto-vacuum property is
|
| +** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
|
| +*/
|
| +int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + return SQLITE_READONLY;
|
| +#else
|
| + BtShared *pBt = p->pBt;
|
| + int rc = SQLITE_OK;
|
| + u8 av = (u8)autoVacuum;
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + if( (pBt->btsFlags & BTS_PAGESIZE_FIXED)!=0 && (av ?1:0)!=pBt->autoVacuum ){
|
| + rc = SQLITE_READONLY;
|
| + }else{
|
| + pBt->autoVacuum = av ?1:0;
|
| + pBt->incrVacuum = av==2 ?1:0;
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +#endif
|
| +}
|
| +
|
| +/*
|
| +** Return the value of the 'auto-vacuum' property. If auto-vacuum is
|
| +** enabled 1 is returned. Otherwise 0.
|
| +*/
|
| +int sqlite3BtreeGetAutoVacuum(Btree *p){
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + return BTREE_AUTOVACUUM_NONE;
|
| +#else
|
| + int rc;
|
| + sqlite3BtreeEnter(p);
|
| + rc = (
|
| + (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
|
| + (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
|
| + BTREE_AUTOVACUUM_INCR
|
| + );
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +#endif
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Get a reference to pPage1 of the database file. This will
|
| +** also acquire a readlock on that file.
|
| +**
|
| +** SQLITE_OK is returned on success. If the file is not a
|
| +** well-formed database file, then SQLITE_CORRUPT is returned.
|
| +** SQLITE_BUSY is returned if the database is locked. SQLITE_NOMEM
|
| +** is returned if we run out of memory.
|
| +*/
|
| +static int lockBtree(BtShared *pBt){
|
| + int rc; /* Result code from subfunctions */
|
| + MemPage *pPage1; /* Page 1 of the database file */
|
| + int nPage; /* Number of pages in the database */
|
| + int nPageFile = 0; /* Number of pages in the database file */
|
| + int nPageHeader; /* Number of pages in the database according to hdr */
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( pBt->pPage1==0 );
|
| + rc = sqlite3PagerSharedLock(pBt->pPager);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + rc = btreeGetPage(pBt, 1, &pPage1, 0);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| +
|
| + /* Do some checking to help insure the file we opened really is
|
| + ** a valid database file.
|
| + */
|
| + nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
|
| + sqlite3PagerPagecount(pBt->pPager, &nPageFile);
|
| + if( nPage==0 || memcmp(24+(u8*)pPage1->aData, 92+(u8*)pPage1->aData,4)!=0 ){
|
| + nPage = nPageFile;
|
| + }
|
| + if( nPage>0 ){
|
| + u32 pageSize;
|
| + u32 usableSize;
|
| + u8 *page1 = pPage1->aData;
|
| + rc = SQLITE_NOTADB;
|
| + /* EVIDENCE-OF: R-43737-39999 Every valid SQLite database file begins
|
| + ** with the following 16 bytes (in hex): 53 51 4c 69 74 65 20 66 6f 72 6d
|
| + ** 61 74 20 33 00. */
|
| + if( memcmp(page1, zMagicHeader, 16)!=0 ){
|
| + goto page1_init_failed;
|
| + }
|
| +
|
| +#ifdef SQLITE_OMIT_WAL
|
| + if( page1[18]>1 ){
|
| + pBt->btsFlags |= BTS_READ_ONLY;
|
| + }
|
| + if( page1[19]>1 ){
|
| + goto page1_init_failed;
|
| + }
|
| +#else
|
| + if( page1[18]>2 ){
|
| + pBt->btsFlags |= BTS_READ_ONLY;
|
| + }
|
| + if( page1[19]>2 ){
|
| + goto page1_init_failed;
|
| + }
|
| +
|
| + /* If the write version is set to 2, this database should be accessed
|
| + ** in WAL mode. If the log is not already open, open it now. Then
|
| + ** return SQLITE_OK and return without populating BtShared.pPage1.
|
| + ** The caller detects this and calls this function again. This is
|
| + ** required as the version of page 1 currently in the page1 buffer
|
| + ** may not be the latest version - there may be a newer one in the log
|
| + ** file.
|
| + */
|
| + if( page1[19]==2 && (pBt->btsFlags & BTS_NO_WAL)==0 ){
|
| + int isOpen = 0;
|
| + rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen);
|
| + if( rc!=SQLITE_OK ){
|
| + goto page1_init_failed;
|
| + }else{
|
| +#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS
|
| + sqlite3 *db;
|
| + Db *pDb;
|
| + if( (db=pBt->db)!=0 && (pDb=db->aDb)!=0 ){
|
| + while( pDb->pBt==0 || pDb->pBt->pBt!=pBt ){ pDb++; }
|
| + if( pDb->bSyncSet==0
|
| + && pDb->safety_level==SQLITE_DEFAULT_SYNCHRONOUS+1
|
| + ){
|
| + pDb->safety_level = SQLITE_DEFAULT_WAL_SYNCHRONOUS+1;
|
| + sqlite3PagerSetFlags(pBt->pPager,
|
| + pDb->safety_level | (db->flags & PAGER_FLAGS_MASK));
|
| + }
|
| + }
|
| +#endif
|
| + if( isOpen==0 ){
|
| + releasePage(pPage1);
|
| + return SQLITE_OK;
|
| + }
|
| + }
|
| + rc = SQLITE_NOTADB;
|
| + }
|
| +#endif
|
| +
|
| + /* EVIDENCE-OF: R-15465-20813 The maximum and minimum embedded payload
|
| + ** fractions and the leaf payload fraction values must be 64, 32, and 32.
|
| + **
|
| + ** The original design allowed these amounts to vary, but as of
|
| + ** version 3.6.0, we require them to be fixed.
|
| + */
|
| + if( memcmp(&page1[21], "\100\040\040",3)!=0 ){
|
| + goto page1_init_failed;
|
| + }
|
| + /* EVIDENCE-OF: R-51873-39618 The page size for a database file is
|
| + ** determined by the 2-byte integer located at an offset of 16 bytes from
|
| + ** the beginning of the database file. */
|
| + pageSize = (page1[16]<<8) | (page1[17]<<16);
|
| + /* EVIDENCE-OF: R-25008-21688 The size of a page is a power of two
|
| + ** between 512 and 65536 inclusive. */
|
| + if( ((pageSize-1)&pageSize)!=0
|
| + || pageSize>SQLITE_MAX_PAGE_SIZE
|
| + || pageSize<=256
|
| + ){
|
| + goto page1_init_failed;
|
| + }
|
| + assert( (pageSize & 7)==0 );
|
| + /* EVIDENCE-OF: R-59310-51205 The "reserved space" size in the 1-byte
|
| + ** integer at offset 20 is the number of bytes of space at the end of
|
| + ** each page to reserve for extensions.
|
| + **
|
| + ** EVIDENCE-OF: R-37497-42412 The size of the reserved region is
|
| + ** determined by the one-byte unsigned integer found at an offset of 20
|
| + ** into the database file header. */
|
| + usableSize = pageSize - page1[20];
|
| + if( (u32)pageSize!=pBt->pageSize ){
|
| + /* After reading the first page of the database assuming a page size
|
| + ** of BtShared.pageSize, we have discovered that the page-size is
|
| + ** actually pageSize. Unlock the database, leave pBt->pPage1 at
|
| + ** zero and return SQLITE_OK. The caller will call this function
|
| + ** again with the correct page-size.
|
| + */
|
| + releasePage(pPage1);
|
| + pBt->usableSize = usableSize;
|
| + pBt->pageSize = pageSize;
|
| + freeTempSpace(pBt);
|
| + rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
|
| + pageSize-usableSize);
|
| + return rc;
|
| + }
|
| + if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPage>nPageFile ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto page1_init_failed;
|
| + }
|
| + /* EVIDENCE-OF: R-28312-64704 However, the usable size is not allowed to
|
| + ** be less than 480. In other words, if the page size is 512, then the
|
| + ** reserved space size cannot exceed 32. */
|
| + if( usableSize<480 ){
|
| + goto page1_init_failed;
|
| + }
|
| + pBt->pageSize = pageSize;
|
| + pBt->usableSize = usableSize;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
|
| + pBt->incrVacuum = (get4byte(&page1[36 + 7*4])?1:0);
|
| +#endif
|
| + }
|
| +
|
| + /* maxLocal is the maximum amount of payload to store locally for
|
| + ** a cell. Make sure it is small enough so that at least minFanout
|
| + ** cells can will fit on one page. We assume a 10-byte page header.
|
| + ** Besides the payload, the cell must store:
|
| + ** 2-byte pointer to the cell
|
| + ** 4-byte child pointer
|
| + ** 9-byte nKey value
|
| + ** 4-byte nData value
|
| + ** 4-byte overflow page pointer
|
| + ** So a cell consists of a 2-byte pointer, a header which is as much as
|
| + ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
|
| + ** page pointer.
|
| + */
|
| + pBt->maxLocal = (u16)((pBt->usableSize-12)*64/255 - 23);
|
| + pBt->minLocal = (u16)((pBt->usableSize-12)*32/255 - 23);
|
| + pBt->maxLeaf = (u16)(pBt->usableSize - 35);
|
| + pBt->minLeaf = (u16)((pBt->usableSize-12)*32/255 - 23);
|
| + if( pBt->maxLocal>127 ){
|
| + pBt->max1bytePayload = 127;
|
| + }else{
|
| + pBt->max1bytePayload = (u8)pBt->maxLocal;
|
| + }
|
| + assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
|
| + pBt->pPage1 = pPage1;
|
| + pBt->nPage = nPage;
|
| + return SQLITE_OK;
|
| +
|
| +page1_init_failed:
|
| + releasePage(pPage1);
|
| + pBt->pPage1 = 0;
|
| + return rc;
|
| +}
|
| +
|
| +#ifndef NDEBUG
|
| +/*
|
| +** Return the number of cursors open on pBt. This is for use
|
| +** in assert() expressions, so it is only compiled if NDEBUG is not
|
| +** defined.
|
| +**
|
| +** Only write cursors are counted if wrOnly is true. If wrOnly is
|
| +** false then all cursors are counted.
|
| +**
|
| +** For the purposes of this routine, a cursor is any cursor that
|
| +** is capable of reading or writing to the database. Cursors that
|
| +** have been tripped into the CURSOR_FAULT state are not counted.
|
| +*/
|
| +static int countValidCursors(BtShared *pBt, int wrOnly){
|
| + BtCursor *pCur;
|
| + int r = 0;
|
| + for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
|
| + if( (wrOnly==0 || (pCur->curFlags & BTCF_WriteFlag)!=0)
|
| + && pCur->eState!=CURSOR_FAULT ) r++;
|
| + }
|
| + return r;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** If there are no outstanding cursors and we are not in the middle
|
| +** of a transaction but there is a read lock on the database, then
|
| +** this routine unrefs the first page of the database file which
|
| +** has the effect of releasing the read lock.
|
| +**
|
| +** If there is a transaction in progress, this routine is a no-op.
|
| +*/
|
| +static void unlockBtreeIfUnused(BtShared *pBt){
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( countValidCursors(pBt,0)==0 || pBt->inTransaction>TRANS_NONE );
|
| + if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){
|
| + MemPage *pPage1 = pBt->pPage1;
|
| + assert( pPage1->aData );
|
| + assert( sqlite3PagerRefcount(pBt->pPager)==1 );
|
| + pBt->pPage1 = 0;
|
| + releasePageNotNull(pPage1);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** If pBt points to an empty file then convert that empty file
|
| +** into a new empty database by initializing the first page of
|
| +** the database.
|
| +*/
|
| +static int newDatabase(BtShared *pBt){
|
| + MemPage *pP1;
|
| + unsigned char *data;
|
| + int rc;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + if( pBt->nPage>0 ){
|
| + return SQLITE_OK;
|
| + }
|
| + pP1 = pBt->pPage1;
|
| + assert( pP1!=0 );
|
| + data = pP1->aData;
|
| + rc = sqlite3PagerWrite(pP1->pDbPage);
|
| + if( rc ) return rc;
|
| + memcpy(data, zMagicHeader, sizeof(zMagicHeader));
|
| + assert( sizeof(zMagicHeader)==16 );
|
| + data[16] = (u8)((pBt->pageSize>>8)&0xff);
|
| + data[17] = (u8)((pBt->pageSize>>16)&0xff);
|
| + data[18] = 1;
|
| + data[19] = 1;
|
| + assert( pBt->usableSize<=pBt->pageSize && pBt->usableSize+255>=pBt->pageSize);
|
| + data[20] = (u8)(pBt->pageSize - pBt->usableSize);
|
| + data[21] = 64;
|
| + data[22] = 32;
|
| + data[23] = 32;
|
| + memset(&data[24], 0, 100-24);
|
| + zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
|
| + pBt->btsFlags |= BTS_PAGESIZE_FIXED;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
|
| + assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
|
| + put4byte(&data[36 + 4*4], pBt->autoVacuum);
|
| + put4byte(&data[36 + 7*4], pBt->incrVacuum);
|
| +#endif
|
| + pBt->nPage = 1;
|
| + data[31] = 1;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Initialize the first page of the database file (creating a database
|
| +** consisting of a single page and no schema objects). Return SQLITE_OK
|
| +** if successful, or an SQLite error code otherwise.
|
| +*/
|
| +int sqlite3BtreeNewDb(Btree *p){
|
| + int rc;
|
| + sqlite3BtreeEnter(p);
|
| + p->pBt->nPage = 0;
|
| + rc = newDatabase(p->pBt);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Attempt to start a new transaction. A write-transaction
|
| +** is started if the second argument is nonzero, otherwise a read-
|
| +** transaction. If the second argument is 2 or more and exclusive
|
| +** transaction is started, meaning that no other process is allowed
|
| +** to access the database. A preexisting transaction may not be
|
| +** upgraded to exclusive by calling this routine a second time - the
|
| +** exclusivity flag only works for a new transaction.
|
| +**
|
| +** A write-transaction must be started before attempting any
|
| +** changes to the database. None of the following routines
|
| +** will work unless a transaction is started first:
|
| +**
|
| +** sqlite3BtreeCreateTable()
|
| +** sqlite3BtreeCreateIndex()
|
| +** sqlite3BtreeClearTable()
|
| +** sqlite3BtreeDropTable()
|
| +** sqlite3BtreeInsert()
|
| +** sqlite3BtreeDelete()
|
| +** sqlite3BtreeUpdateMeta()
|
| +**
|
| +** If an initial attempt to acquire the lock fails because of lock contention
|
| +** and the database was previously unlocked, then invoke the busy handler
|
| +** if there is one. But if there was previously a read-lock, do not
|
| +** invoke the busy handler - just return SQLITE_BUSY. SQLITE_BUSY is
|
| +** returned when there is already a read-lock in order to avoid a deadlock.
|
| +**
|
| +** Suppose there are two processes A and B. A has a read lock and B has
|
| +** a reserved lock. B tries to promote to exclusive but is blocked because
|
| +** of A's read lock. A tries to promote to reserved but is blocked by B.
|
| +** One or the other of the two processes must give way or there can be
|
| +** no progress. By returning SQLITE_BUSY and not invoking the busy callback
|
| +** when A already has a read lock, we encourage A to give up and let B
|
| +** proceed.
|
| +*/
|
| +int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
|
| + BtShared *pBt = p->pBt;
|
| + int rc = SQLITE_OK;
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + btreeIntegrity(p);
|
| +
|
| + /* If the btree is already in a write-transaction, or it
|
| + ** is already in a read-transaction and a read-transaction
|
| + ** is requested, this is a no-op.
|
| + */
|
| + if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
|
| + goto trans_begun;
|
| + }
|
| + assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 );
|
| +
|
| + /* Write transactions are not possible on a read-only database */
|
| + if( (pBt->btsFlags & BTS_READ_ONLY)!=0 && wrflag ){
|
| + rc = SQLITE_READONLY;
|
| + goto trans_begun;
|
| + }
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + {
|
| + sqlite3 *pBlock = 0;
|
| + /* If another database handle has already opened a write transaction
|
| + ** on this shared-btree structure and a second write transaction is
|
| + ** requested, return SQLITE_LOCKED.
|
| + */
|
| + if( (wrflag && pBt->inTransaction==TRANS_WRITE)
|
| + || (pBt->btsFlags & BTS_PENDING)!=0
|
| + ){
|
| + pBlock = pBt->pWriter->db;
|
| + }else if( wrflag>1 ){
|
| + BtLock *pIter;
|
| + for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
|
| + if( pIter->pBtree!=p ){
|
| + pBlock = pIter->pBtree->db;
|
| + break;
|
| + }
|
| + }
|
| + }
|
| + if( pBlock ){
|
| + sqlite3ConnectionBlocked(p->db, pBlock);
|
| + rc = SQLITE_LOCKED_SHAREDCACHE;
|
| + goto trans_begun;
|
| + }
|
| + }
|
| +#endif
|
| +
|
| + /* Any read-only or read-write transaction implies a read-lock on
|
| + ** page 1. So if some other shared-cache client already has a write-lock
|
| + ** on page 1, the transaction cannot be opened. */
|
| + rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
|
| + if( SQLITE_OK!=rc ) goto trans_begun;
|
| +
|
| + pBt->btsFlags &= ~BTS_INITIALLY_EMPTY;
|
| + if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY;
|
| + do {
|
| + /* Call lockBtree() until either pBt->pPage1 is populated or
|
| + ** lockBtree() returns something other than SQLITE_OK. lockBtree()
|
| + ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
|
| + ** reading page 1 it discovers that the page-size of the database
|
| + ** file is not pBt->pageSize. In this case lockBtree() will update
|
| + ** pBt->pageSize to the page-size of the file on disk.
|
| + */
|
| + while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) );
|
| +
|
| + if( rc==SQLITE_OK && wrflag ){
|
| + if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
|
| + rc = SQLITE_READONLY;
|
| + }else{
|
| + rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db));
|
| + if( rc==SQLITE_OK ){
|
| + rc = newDatabase(pBt);
|
| + }
|
| + }
|
| + }
|
| +
|
| + if( rc!=SQLITE_OK ){
|
| + unlockBtreeIfUnused(pBt);
|
| + }
|
| + }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
|
| + btreeInvokeBusyHandler(pBt) );
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + if( p->inTrans==TRANS_NONE ){
|
| + pBt->nTransaction++;
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + if( p->sharable ){
|
| + assert( p->lock.pBtree==p && p->lock.iTable==1 );
|
| + p->lock.eLock = READ_LOCK;
|
| + p->lock.pNext = pBt->pLock;
|
| + pBt->pLock = &p->lock;
|
| + }
|
| +#endif
|
| + }
|
| + p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
|
| + if( p->inTrans>pBt->inTransaction ){
|
| + pBt->inTransaction = p->inTrans;
|
| + }
|
| + if( wrflag ){
|
| + MemPage *pPage1 = pBt->pPage1;
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| + assert( !pBt->pWriter );
|
| + pBt->pWriter = p;
|
| + pBt->btsFlags &= ~BTS_EXCLUSIVE;
|
| + if( wrflag>1 ) pBt->btsFlags |= BTS_EXCLUSIVE;
|
| +#endif
|
| +
|
| + /* If the db-size header field is incorrect (as it may be if an old
|
| + ** client has been writing the database file), update it now. Doing
|
| + ** this sooner rather than later means the database size can safely
|
| + ** re-read the database size from page 1 if a savepoint or transaction
|
| + ** rollback occurs within the transaction.
|
| + */
|
| + if( pBt->nPage!=get4byte(&pPage1->aData[28]) ){
|
| + rc = sqlite3PagerWrite(pPage1->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + put4byte(&pPage1->aData[28], pBt->nPage);
|
| + }
|
| + }
|
| + }
|
| + }
|
| +
|
| +
|
| +trans_begun:
|
| + if( rc==SQLITE_OK && wrflag ){
|
| + /* This call makes sure that the pager has the correct number of
|
| + ** open savepoints. If the second parameter is greater than 0 and
|
| + ** the sub-journal is not already open, then it will be opened here.
|
| + */
|
| + rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
|
| + }
|
| +
|
| + btreeIntegrity(p);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +
|
| +/*
|
| +** Set the pointer-map entries for all children of page pPage. Also, if
|
| +** pPage contains cells that point to overflow pages, set the pointer
|
| +** map entries for the overflow pages as well.
|
| +*/
|
| +static int setChildPtrmaps(MemPage *pPage){
|
| + int i; /* Counter variable */
|
| + int nCell; /* Number of cells in page pPage */
|
| + int rc; /* Return code */
|
| + BtShared *pBt = pPage->pBt;
|
| + Pgno pgno = pPage->pgno;
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + rc = btreeInitPage(pPage);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + nCell = pPage->nCell;
|
| +
|
| + for(i=0; i<nCell; i++){
|
| + u8 *pCell = findCell(pPage, i);
|
| +
|
| + ptrmapPutOvflPtr(pPage, pCell, &rc);
|
| +
|
| + if( !pPage->leaf ){
|
| + Pgno childPgno = get4byte(pCell);
|
| + ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
|
| + }
|
| + }
|
| +
|
| + if( !pPage->leaf ){
|
| + Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
|
| + ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Somewhere on pPage is a pointer to page iFrom. Modify this pointer so
|
| +** that it points to iTo. Parameter eType describes the type of pointer to
|
| +** be modified, as follows:
|
| +**
|
| +** PTRMAP_BTREE: pPage is a btree-page. The pointer points at a child
|
| +** page of pPage.
|
| +**
|
| +** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
|
| +** page pointed to by one of the cells on pPage.
|
| +**
|
| +** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
|
| +** overflow page in the list.
|
| +*/
|
| +static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + if( eType==PTRMAP_OVERFLOW2 ){
|
| + /* The pointer is always the first 4 bytes of the page in this case. */
|
| + if( get4byte(pPage->aData)!=iFrom ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + put4byte(pPage->aData, iTo);
|
| + }else{
|
| + int i;
|
| + int nCell;
|
| + int rc;
|
| +
|
| + rc = btreeInitPage(pPage);
|
| + if( rc ) return rc;
|
| + nCell = pPage->nCell;
|
| +
|
| + for(i=0; i<nCell; i++){
|
| + u8 *pCell = findCell(pPage, i);
|
| + if( eType==PTRMAP_OVERFLOW1 ){
|
| + CellInfo info;
|
| + pPage->xParseCell(pPage, pCell, &info);
|
| + if( info.nLocal<info.nPayload ){
|
| + if( pCell+info.nSize > pPage->aData+pPage->pBt->usableSize ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + if( iFrom==get4byte(pCell+info.nSize-4) ){
|
| + put4byte(pCell+info.nSize-4, iTo);
|
| + break;
|
| + }
|
| + }
|
| + }else{
|
| + if( get4byte(pCell)==iFrom ){
|
| + put4byte(pCell, iTo);
|
| + break;
|
| + }
|
| + }
|
| + }
|
| +
|
| + if( i==nCell ){
|
| + if( eType!=PTRMAP_BTREE ||
|
| + get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
|
| + }
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Move the open database page pDbPage to location iFreePage in the
|
| +** database. The pDbPage reference remains valid.
|
| +**
|
| +** The isCommit flag indicates that there is no need to remember that
|
| +** the journal needs to be sync()ed before database page pDbPage->pgno
|
| +** can be written to. The caller has already promised not to write to that
|
| +** page.
|
| +*/
|
| +static int relocatePage(
|
| + BtShared *pBt, /* Btree */
|
| + MemPage *pDbPage, /* Open page to move */
|
| + u8 eType, /* Pointer map 'type' entry for pDbPage */
|
| + Pgno iPtrPage, /* Pointer map 'page-no' entry for pDbPage */
|
| + Pgno iFreePage, /* The location to move pDbPage to */
|
| + int isCommit /* isCommit flag passed to sqlite3PagerMovepage */
|
| +){
|
| + MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */
|
| + Pgno iDbPage = pDbPage->pgno;
|
| + Pager *pPager = pBt->pPager;
|
| + int rc;
|
| +
|
| + assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 ||
|
| + eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( pDbPage->pBt==pBt );
|
| +
|
| + /* Move page iDbPage from its current location to page number iFreePage */
|
| + TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
|
| + iDbPage, iFreePage, iPtrPage, eType));
|
| + rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage, isCommit);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + pDbPage->pgno = iFreePage;
|
| +
|
| + /* If pDbPage was a btree-page, then it may have child pages and/or cells
|
| + ** that point to overflow pages. The pointer map entries for all these
|
| + ** pages need to be changed.
|
| + **
|
| + ** If pDbPage is an overflow page, then the first 4 bytes may store a
|
| + ** pointer to a subsequent overflow page. If this is the case, then
|
| + ** the pointer map needs to be updated for the subsequent overflow page.
|
| + */
|
| + if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
|
| + rc = setChildPtrmaps(pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + }else{
|
| + Pgno nextOvfl = get4byte(pDbPage->aData);
|
| + if( nextOvfl!=0 ){
|
| + ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage, &rc);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + }
|
| + }
|
| +
|
| + /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
|
| + ** that it points at iFreePage. Also fix the pointer map entry for
|
| + ** iPtrPage.
|
| + */
|
| + if( eType!=PTRMAP_ROOTPAGE ){
|
| + rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + rc = sqlite3PagerWrite(pPtrPage->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(pPtrPage);
|
| + return rc;
|
| + }
|
| + rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
|
| + releasePage(pPtrPage);
|
| + if( rc==SQLITE_OK ){
|
| + ptrmapPut(pBt, iFreePage, eType, iPtrPage, &rc);
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/* Forward declaration required by incrVacuumStep(). */
|
| +static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
|
| +
|
| +/*
|
| +** Perform a single step of an incremental-vacuum. If successful, return
|
| +** SQLITE_OK. If there is no work to do (and therefore no point in
|
| +** calling this function again), return SQLITE_DONE. Or, if an error
|
| +** occurs, return some other error code.
|
| +**
|
| +** More specifically, this function attempts to re-organize the database so
|
| +** that the last page of the file currently in use is no longer in use.
|
| +**
|
| +** Parameter nFin is the number of pages that this database would contain
|
| +** were this function called until it returns SQLITE_DONE.
|
| +**
|
| +** If the bCommit parameter is non-zero, this function assumes that the
|
| +** caller will keep calling incrVacuumStep() until it returns SQLITE_DONE
|
| +** or an error. bCommit is passed true for an auto-vacuum-on-commit
|
| +** operation, or false for an incremental vacuum.
|
| +*/
|
| +static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg, int bCommit){
|
| + Pgno nFreeList; /* Number of pages still on the free-list */
|
| + int rc;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( iLastPg>nFin );
|
| +
|
| + if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
|
| + u8 eType;
|
| + Pgno iPtrPage;
|
| +
|
| + nFreeList = get4byte(&pBt->pPage1->aData[36]);
|
| + if( nFreeList==0 ){
|
| + return SQLITE_DONE;
|
| + }
|
| +
|
| + rc = ptrmapGet(pBt, iLastPg, &eType, &iPtrPage);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + if( eType==PTRMAP_ROOTPAGE ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| +
|
| + if( eType==PTRMAP_FREEPAGE ){
|
| + if( bCommit==0 ){
|
| + /* Remove the page from the files free-list. This is not required
|
| + ** if bCommit is non-zero. In that case, the free-list will be
|
| + ** truncated to zero after this function returns, so it doesn't
|
| + ** matter if it still contains some garbage entries.
|
| + */
|
| + Pgno iFreePg;
|
| + MemPage *pFreePg;
|
| + rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, BTALLOC_EXACT);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + assert( iFreePg==iLastPg );
|
| + releasePage(pFreePg);
|
| + }
|
| + } else {
|
| + Pgno iFreePg; /* Index of free page to move pLastPg to */
|
| + MemPage *pLastPg;
|
| + u8 eMode = BTALLOC_ANY; /* Mode parameter for allocateBtreePage() */
|
| + Pgno iNear = 0; /* nearby parameter for allocateBtreePage() */
|
| +
|
| + rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| +
|
| + /* If bCommit is zero, this loop runs exactly once and page pLastPg
|
| + ** is swapped with the first free page pulled off the free list.
|
| + **
|
| + ** On the other hand, if bCommit is greater than zero, then keep
|
| + ** looping until a free-page located within the first nFin pages
|
| + ** of the file is found.
|
| + */
|
| + if( bCommit==0 ){
|
| + eMode = BTALLOC_LE;
|
| + iNear = nFin;
|
| + }
|
| + do {
|
| + MemPage *pFreePg;
|
| + rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iNear, eMode);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(pLastPg);
|
| + return rc;
|
| + }
|
| + releasePage(pFreePg);
|
| + }while( bCommit && iFreePg>nFin );
|
| + assert( iFreePg<iLastPg );
|
| +
|
| + rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, bCommit);
|
| + releasePage(pLastPg);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + }
|
| + }
|
| +
|
| + if( bCommit==0 ){
|
| + do {
|
| + iLastPg--;
|
| + }while( iLastPg==PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg) );
|
| + pBt->bDoTruncate = 1;
|
| + pBt->nPage = iLastPg;
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** The database opened by the first argument is an auto-vacuum database
|
| +** nOrig pages in size containing nFree free pages. Return the expected
|
| +** size of the database in pages following an auto-vacuum operation.
|
| +*/
|
| +static Pgno finalDbSize(BtShared *pBt, Pgno nOrig, Pgno nFree){
|
| + int nEntry; /* Number of entries on one ptrmap page */
|
| + Pgno nPtrmap; /* Number of PtrMap pages to be freed */
|
| + Pgno nFin; /* Return value */
|
| +
|
| + nEntry = pBt->usableSize/5;
|
| + nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
|
| + nFin = nOrig - nFree - nPtrmap;
|
| + if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
|
| + nFin--;
|
| + }
|
| + while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
|
| + nFin--;
|
| + }
|
| +
|
| + return nFin;
|
| +}
|
| +
|
| +/*
|
| +** A write-transaction must be opened before calling this function.
|
| +** It performs a single unit of work towards an incremental vacuum.
|
| +**
|
| +** If the incremental vacuum is finished after this function has run,
|
| +** SQLITE_DONE is returned. If it is not finished, but no error occurred,
|
| +** SQLITE_OK is returned. Otherwise an SQLite error code.
|
| +*/
|
| +int sqlite3BtreeIncrVacuum(Btree *p){
|
| + int rc;
|
| + BtShared *pBt = p->pBt;
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
|
| + if( !pBt->autoVacuum ){
|
| + rc = SQLITE_DONE;
|
| + }else{
|
| + Pgno nOrig = btreePagecount(pBt);
|
| + Pgno nFree = get4byte(&pBt->pPage1->aData[36]);
|
| + Pgno nFin = finalDbSize(pBt, nOrig, nFree);
|
| +
|
| + if( nOrig<nFin ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + }else if( nFree>0 ){
|
| + rc = saveAllCursors(pBt, 0, 0);
|
| + if( rc==SQLITE_OK ){
|
| + invalidateAllOverflowCache(pBt);
|
| + rc = incrVacuumStep(pBt, nFin, nOrig, 0);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
|
| + put4byte(&pBt->pPage1->aData[28], pBt->nPage);
|
| + }
|
| + }else{
|
| + rc = SQLITE_DONE;
|
| + }
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This routine is called prior to sqlite3PagerCommit when a transaction
|
| +** is committed for an auto-vacuum database.
|
| +**
|
| +** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
|
| +** the database file should be truncated to during the commit process.
|
| +** i.e. the database has been reorganized so that only the first *pnTrunc
|
| +** pages are in use.
|
| +*/
|
| +static int autoVacuumCommit(BtShared *pBt){
|
| + int rc = SQLITE_OK;
|
| + Pager *pPager = pBt->pPager;
|
| + VVA_ONLY( int nRef = sqlite3PagerRefcount(pPager); )
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + invalidateAllOverflowCache(pBt);
|
| + assert(pBt->autoVacuum);
|
| + if( !pBt->incrVacuum ){
|
| + Pgno nFin; /* Number of pages in database after autovacuuming */
|
| + Pgno nFree; /* Number of pages on the freelist initially */
|
| + Pgno iFree; /* The next page to be freed */
|
| + Pgno nOrig; /* Database size before freeing */
|
| +
|
| + nOrig = btreePagecount(pBt);
|
| + if( PTRMAP_ISPAGE(pBt, nOrig) || nOrig==PENDING_BYTE_PAGE(pBt) ){
|
| + /* It is not possible to create a database for which the final page
|
| + ** is either a pointer-map page or the pending-byte page. If one
|
| + ** is encountered, this indicates corruption.
|
| + */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| +
|
| + nFree = get4byte(&pBt->pPage1->aData[36]);
|
| + nFin = finalDbSize(pBt, nOrig, nFree);
|
| + if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
|
| + if( nFin<nOrig ){
|
| + rc = saveAllCursors(pBt, 0, 0);
|
| + }
|
| + for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
|
| + rc = incrVacuumStep(pBt, nFin, iFree, 1);
|
| + }
|
| + if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
|
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
|
| + put4byte(&pBt->pPage1->aData[32], 0);
|
| + put4byte(&pBt->pPage1->aData[36], 0);
|
| + put4byte(&pBt->pPage1->aData[28], nFin);
|
| + pBt->bDoTruncate = 1;
|
| + pBt->nPage = nFin;
|
| + }
|
| + if( rc!=SQLITE_OK ){
|
| + sqlite3PagerRollback(pPager);
|
| + }
|
| + }
|
| +
|
| + assert( nRef>=sqlite3PagerRefcount(pPager) );
|
| + return rc;
|
| +}
|
| +
|
| +#else /* ifndef SQLITE_OMIT_AUTOVACUUM */
|
| +# define setChildPtrmaps(x) SQLITE_OK
|
| +#endif
|
| +
|
| +/*
|
| +** This routine does the first phase of a two-phase commit. This routine
|
| +** causes a rollback journal to be created (if it does not already exist)
|
| +** and populated with enough information so that if a power loss occurs
|
| +** the database can be restored to its original state by playing back
|
| +** the journal. Then the contents of the journal are flushed out to
|
| +** the disk. After the journal is safely on oxide, the changes to the
|
| +** database are written into the database file and flushed to oxide.
|
| +** At the end of this call, the rollback journal still exists on the
|
| +** disk and we are still holding all locks, so the transaction has not
|
| +** committed. See sqlite3BtreeCommitPhaseTwo() for the second phase of the
|
| +** commit process.
|
| +**
|
| +** This call is a no-op if no write-transaction is currently active on pBt.
|
| +**
|
| +** Otherwise, sync the database file for the btree pBt. zMaster points to
|
| +** the name of a master journal file that should be written into the
|
| +** individual journal file, or is NULL, indicating no master journal file
|
| +** (single database transaction).
|
| +**
|
| +** When this is called, the master journal should already have been
|
| +** created, populated with this journal pointer and synced to disk.
|
| +**
|
| +** Once this is routine has returned, the only thing required to commit
|
| +** the write-transaction for this database file is to delete the journal.
|
| +*/
|
| +int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
|
| + int rc = SQLITE_OK;
|
| + if( p->inTrans==TRANS_WRITE ){
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3BtreeEnter(p);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum ){
|
| + rc = autoVacuumCommit(pBt);
|
| + if( rc!=SQLITE_OK ){
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| + }
|
| + }
|
| + if( pBt->bDoTruncate ){
|
| + sqlite3PagerTruncateImage(pBt->pPager, pBt->nPage);
|
| + }
|
| +#endif
|
| + rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, 0);
|
| + sqlite3BtreeLeave(p);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called from both BtreeCommitPhaseTwo() and BtreeRollback()
|
| +** at the conclusion of a transaction.
|
| +*/
|
| +static void btreeEndTransaction(Btree *p){
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3 *db = p->db;
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + pBt->bDoTruncate = 0;
|
| +#endif
|
| + if( p->inTrans>TRANS_NONE && db->nVdbeRead>1 ){
|
| + /* If there are other active statements that belong to this database
|
| + ** handle, downgrade to a read-only transaction. The other statements
|
| + ** may still be reading from the database. */
|
| + downgradeAllSharedCacheTableLocks(p);
|
| + p->inTrans = TRANS_READ;
|
| + }else{
|
| + /* If the handle had any kind of transaction open, decrement the
|
| + ** transaction count of the shared btree. If the transaction count
|
| + ** reaches 0, set the shared state to TRANS_NONE. The unlockBtreeIfUnused()
|
| + ** call below will unlock the pager. */
|
| + if( p->inTrans!=TRANS_NONE ){
|
| + clearAllSharedCacheTableLocks(p);
|
| + pBt->nTransaction--;
|
| + if( 0==pBt->nTransaction ){
|
| + pBt->inTransaction = TRANS_NONE;
|
| + }
|
| + }
|
| +
|
| + /* Set the current transaction state to TRANS_NONE and unlock the
|
| + ** pager if this call closed the only read or write transaction. */
|
| + p->inTrans = TRANS_NONE;
|
| + unlockBtreeIfUnused(pBt);
|
| + }
|
| +
|
| + btreeIntegrity(p);
|
| +}
|
| +
|
| +/*
|
| +** Commit the transaction currently in progress.
|
| +**
|
| +** This routine implements the second phase of a 2-phase commit. The
|
| +** sqlite3BtreeCommitPhaseOne() routine does the first phase and should
|
| +** be invoked prior to calling this routine. The sqlite3BtreeCommitPhaseOne()
|
| +** routine did all the work of writing information out to disk and flushing the
|
| +** contents so that they are written onto the disk platter. All this
|
| +** routine has to do is delete or truncate or zero the header in the
|
| +** the rollback journal (which causes the transaction to commit) and
|
| +** drop locks.
|
| +**
|
| +** Normally, if an error occurs while the pager layer is attempting to
|
| +** finalize the underlying journal file, this function returns an error and
|
| +** the upper layer will attempt a rollback. However, if the second argument
|
| +** is non-zero then this b-tree transaction is part of a multi-file
|
| +** transaction. In this case, the transaction has already been committed
|
| +** (by deleting a master journal file) and the caller will ignore this
|
| +** functions return code. So, even if an error occurs in the pager layer,
|
| +** reset the b-tree objects internal state to indicate that the write
|
| +** transaction has been closed. This is quite safe, as the pager will have
|
| +** transitioned to the error state.
|
| +**
|
| +** This will release the write lock on the database file. If there
|
| +** are no active cursors, it also releases the read lock.
|
| +*/
|
| +int sqlite3BtreeCommitPhaseTwo(Btree *p, int bCleanup){
|
| +
|
| + if( p->inTrans==TRANS_NONE ) return SQLITE_OK;
|
| + sqlite3BtreeEnter(p);
|
| + btreeIntegrity(p);
|
| +
|
| + /* If the handle has a write-transaction open, commit the shared-btrees
|
| + ** transaction and set the shared state to TRANS_READ.
|
| + */
|
| + if( p->inTrans==TRANS_WRITE ){
|
| + int rc;
|
| + BtShared *pBt = p->pBt;
|
| + assert( pBt->inTransaction==TRANS_WRITE );
|
| + assert( pBt->nTransaction>0 );
|
| + rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
|
| + if( rc!=SQLITE_OK && bCleanup==0 ){
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| + }
|
| + p->iDataVersion--; /* Compensate for pPager->iDataVersion++; */
|
| + pBt->inTransaction = TRANS_READ;
|
| + btreeClearHasContent(pBt);
|
| + }
|
| +
|
| + btreeEndTransaction(p);
|
| + sqlite3BtreeLeave(p);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Do both phases of a commit.
|
| +*/
|
| +int sqlite3BtreeCommit(Btree *p){
|
| + int rc;
|
| + sqlite3BtreeEnter(p);
|
| + rc = sqlite3BtreeCommitPhaseOne(p, 0);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3BtreeCommitPhaseTwo(p, 0);
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This routine sets the state to CURSOR_FAULT and the error
|
| +** code to errCode for every cursor on any BtShared that pBtree
|
| +** references. Or if the writeOnly flag is set to 1, then only
|
| +** trip write cursors and leave read cursors unchanged.
|
| +**
|
| +** Every cursor is a candidate to be tripped, including cursors
|
| +** that belong to other database connections that happen to be
|
| +** sharing the cache with pBtree.
|
| +**
|
| +** This routine gets called when a rollback occurs. If the writeOnly
|
| +** flag is true, then only write-cursors need be tripped - read-only
|
| +** cursors save their current positions so that they may continue
|
| +** following the rollback. Or, if writeOnly is false, all cursors are
|
| +** tripped. In general, writeOnly is false if the transaction being
|
| +** rolled back modified the database schema. In this case b-tree root
|
| +** pages may be moved or deleted from the database altogether, making
|
| +** it unsafe for read cursors to continue.
|
| +**
|
| +** If the writeOnly flag is true and an error is encountered while
|
| +** saving the current position of a read-only cursor, all cursors,
|
| +** including all read-cursors are tripped.
|
| +**
|
| +** SQLITE_OK is returned if successful, or if an error occurs while
|
| +** saving a cursor position, an SQLite error code.
|
| +*/
|
| +int sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode, int writeOnly){
|
| + BtCursor *p;
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( (writeOnly==0 || writeOnly==1) && BTCF_WriteFlag==1 );
|
| + if( pBtree ){
|
| + sqlite3BtreeEnter(pBtree);
|
| + for(p=pBtree->pBt->pCursor; p; p=p->pNext){
|
| + int i;
|
| + if( writeOnly && (p->curFlags & BTCF_WriteFlag)==0 ){
|
| + if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){
|
| + rc = saveCursorPosition(p);
|
| + if( rc!=SQLITE_OK ){
|
| + (void)sqlite3BtreeTripAllCursors(pBtree, rc, 0);
|
| + break;
|
| + }
|
| + }
|
| + }else{
|
| + sqlite3BtreeClearCursor(p);
|
| + p->eState = CURSOR_FAULT;
|
| + p->skipNext = errCode;
|
| + }
|
| + for(i=0; i<=p->iPage; i++){
|
| + releasePage(p->apPage[i]);
|
| + p->apPage[i] = 0;
|
| + }
|
| + }
|
| + sqlite3BtreeLeave(pBtree);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Rollback the transaction in progress.
|
| +**
|
| +** If tripCode is not SQLITE_OK then cursors will be invalidated (tripped).
|
| +** Only write cursors are tripped if writeOnly is true but all cursors are
|
| +** tripped if writeOnly is false. Any attempt to use
|
| +** a tripped cursor will result in an error.
|
| +**
|
| +** This will release the write lock on the database file. If there
|
| +** are no active cursors, it also releases the read lock.
|
| +*/
|
| +int sqlite3BtreeRollback(Btree *p, int tripCode, int writeOnly){
|
| + int rc;
|
| + BtShared *pBt = p->pBt;
|
| + MemPage *pPage1;
|
| +
|
| + assert( writeOnly==1 || writeOnly==0 );
|
| + assert( tripCode==SQLITE_ABORT_ROLLBACK || tripCode==SQLITE_OK );
|
| + sqlite3BtreeEnter(p);
|
| + if( tripCode==SQLITE_OK ){
|
| + rc = tripCode = saveAllCursors(pBt, 0, 0);
|
| + if( rc ) writeOnly = 0;
|
| + }else{
|
| + rc = SQLITE_OK;
|
| + }
|
| + if( tripCode ){
|
| + int rc2 = sqlite3BtreeTripAllCursors(p, tripCode, writeOnly);
|
| + assert( rc==SQLITE_OK || (writeOnly==0 && rc2==SQLITE_OK) );
|
| + if( rc2!=SQLITE_OK ) rc = rc2;
|
| + }
|
| + btreeIntegrity(p);
|
| +
|
| + if( p->inTrans==TRANS_WRITE ){
|
| + int rc2;
|
| +
|
| + assert( TRANS_WRITE==pBt->inTransaction );
|
| + rc2 = sqlite3PagerRollback(pBt->pPager);
|
| + if( rc2!=SQLITE_OK ){
|
| + rc = rc2;
|
| + }
|
| +
|
| + /* The rollback may have destroyed the pPage1->aData value. So
|
| + ** call btreeGetPage() on page 1 again to make
|
| + ** sure pPage1->aData is set correctly. */
|
| + if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
|
| + int nPage = get4byte(28+(u8*)pPage1->aData);
|
| + testcase( nPage==0 );
|
| + if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
|
| + testcase( pBt->nPage!=nPage );
|
| + pBt->nPage = nPage;
|
| + releasePage(pPage1);
|
| + }
|
| + assert( countValidCursors(pBt, 1)==0 );
|
| + pBt->inTransaction = TRANS_READ;
|
| + btreeClearHasContent(pBt);
|
| + }
|
| +
|
| + btreeEndTransaction(p);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Start a statement subtransaction. The subtransaction can be rolled
|
| +** back independently of the main transaction. You must start a transaction
|
| +** before starting a subtransaction. The subtransaction is ended automatically
|
| +** if the main transaction commits or rolls back.
|
| +**
|
| +** Statement subtransactions are used around individual SQL statements
|
| +** that are contained within a BEGIN...COMMIT block. If a constraint
|
| +** error occurs within the statement, the effect of that one statement
|
| +** can be rolled back without having to rollback the entire transaction.
|
| +**
|
| +** A statement sub-transaction is implemented as an anonymous savepoint. The
|
| +** value passed as the second parameter is the total number of savepoints,
|
| +** including the new anonymous savepoint, open on the B-Tree. i.e. if there
|
| +** are no active savepoints and no other statement-transactions open,
|
| +** iStatement is 1. This anonymous savepoint can be released or rolled back
|
| +** using the sqlite3BtreeSavepoint() function.
|
| +*/
|
| +int sqlite3BtreeBeginStmt(Btree *p, int iStatement){
|
| + int rc;
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3BtreeEnter(p);
|
| + assert( p->inTrans==TRANS_WRITE );
|
| + assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
|
| + assert( iStatement>0 );
|
| + assert( iStatement>p->db->nSavepoint );
|
| + assert( pBt->inTransaction==TRANS_WRITE );
|
| + /* At the pager level, a statement transaction is a savepoint with
|
| + ** an index greater than all savepoints created explicitly using
|
| + ** SQL statements. It is illegal to open, release or rollback any
|
| + ** such savepoints while the statement transaction savepoint is active.
|
| + */
|
| + rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** The second argument to this function, op, is always SAVEPOINT_ROLLBACK
|
| +** or SAVEPOINT_RELEASE. This function either releases or rolls back the
|
| +** savepoint identified by parameter iSavepoint, depending on the value
|
| +** of op.
|
| +**
|
| +** Normally, iSavepoint is greater than or equal to zero. However, if op is
|
| +** SAVEPOINT_ROLLBACK, then iSavepoint may also be -1. In this case the
|
| +** contents of the entire transaction are rolled back. This is different
|
| +** from a normal transaction rollback, as no locks are released and the
|
| +** transaction remains open.
|
| +*/
|
| +int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
|
| + int rc = SQLITE_OK;
|
| + if( p && p->inTrans==TRANS_WRITE ){
|
| + BtShared *pBt = p->pBt;
|
| + assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
|
| + assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) );
|
| + sqlite3BtreeEnter(p);
|
| + if( op==SAVEPOINT_ROLLBACK ){
|
| + rc = saveAllCursors(pBt, 0, 0);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + if( iSavepoint<0 && (pBt->btsFlags & BTS_INITIALLY_EMPTY)!=0 ){
|
| + pBt->nPage = 0;
|
| + }
|
| + rc = newDatabase(pBt);
|
| + pBt->nPage = get4byte(28 + pBt->pPage1->aData);
|
| +
|
| + /* The database size was written into the offset 28 of the header
|
| + ** when the transaction started, so we know that the value at offset
|
| + ** 28 is nonzero. */
|
| + assert( pBt->nPage>0 );
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Create a new cursor for the BTree whose root is on the page
|
| +** iTable. If a read-only cursor is requested, it is assumed that
|
| +** the caller already has at least a read-only transaction open
|
| +** on the database already. If a write-cursor is requested, then
|
| +** the caller is assumed to have an open write transaction.
|
| +**
|
| +** If the BTREE_WRCSR bit of wrFlag is clear, then the cursor can only
|
| +** be used for reading. If the BTREE_WRCSR bit is set, then the cursor
|
| +** can be used for reading or for writing if other conditions for writing
|
| +** are also met. These are the conditions that must be met in order
|
| +** for writing to be allowed:
|
| +**
|
| +** 1: The cursor must have been opened with wrFlag containing BTREE_WRCSR
|
| +**
|
| +** 2: Other database connections that share the same pager cache
|
| +** but which are not in the READ_UNCOMMITTED state may not have
|
| +** cursors open with wrFlag==0 on the same table. Otherwise
|
| +** the changes made by this write cursor would be visible to
|
| +** the read cursors in the other database connection.
|
| +**
|
| +** 3: The database must be writable (not on read-only media)
|
| +**
|
| +** 4: There must be an active transaction.
|
| +**
|
| +** The BTREE_FORDELETE bit of wrFlag may optionally be set if BTREE_WRCSR
|
| +** is set. If FORDELETE is set, that is a hint to the implementation that
|
| +** this cursor will only be used to seek to and delete entries of an index
|
| +** as part of a larger DELETE statement. The FORDELETE hint is not used by
|
| +** this implementation. But in a hypothetical alternative storage engine
|
| +** in which index entries are automatically deleted when corresponding table
|
| +** rows are deleted, the FORDELETE flag is a hint that all SEEK and DELETE
|
| +** operations on this cursor can be no-ops and all READ operations can
|
| +** return a null row (2-bytes: 0x01 0x00).
|
| +**
|
| +** No checking is done to make sure that page iTable really is the
|
| +** root page of a b-tree. If it is not, then the cursor acquired
|
| +** will not work correctly.
|
| +**
|
| +** It is assumed that the sqlite3BtreeCursorZero() has been called
|
| +** on pCur to initialize the memory space prior to invoking this routine.
|
| +*/
|
| +static int btreeCursor(
|
| + Btree *p, /* The btree */
|
| + int iTable, /* Root page of table to open */
|
| + int wrFlag, /* 1 to write. 0 read-only */
|
| + struct KeyInfo *pKeyInfo, /* First arg to comparison function */
|
| + BtCursor *pCur /* Space for new cursor */
|
| +){
|
| + BtShared *pBt = p->pBt; /* Shared b-tree handle */
|
| + BtCursor *pX; /* Looping over other all cursors */
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( wrFlag==0
|
| + || wrFlag==BTREE_WRCSR
|
| + || wrFlag==(BTREE_WRCSR|BTREE_FORDELETE)
|
| + );
|
| +
|
| + /* The following assert statements verify that if this is a sharable
|
| + ** b-tree database, the connection is holding the required table locks,
|
| + ** and that no other connection has any open cursor that conflicts with
|
| + ** this lock. */
|
| + assert( hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, (wrFlag?2:1)) );
|
| + assert( wrFlag==0 || !hasReadConflicts(p, iTable) );
|
| +
|
| + /* Assert that the caller has opened the required transaction. */
|
| + assert( p->inTrans>TRANS_NONE );
|
| + assert( wrFlag==0 || p->inTrans==TRANS_WRITE );
|
| + assert( pBt->pPage1 && pBt->pPage1->aData );
|
| + assert( wrFlag==0 || (pBt->btsFlags & BTS_READ_ONLY)==0 );
|
| +
|
| + if( wrFlag ){
|
| + allocateTempSpace(pBt);
|
| + if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM_BKPT;
|
| + }
|
| + if( iTable==1 && btreePagecount(pBt)==0 ){
|
| + assert( wrFlag==0 );
|
| + iTable = 0;
|
| + }
|
| +
|
| + /* Now that no other errors can occur, finish filling in the BtCursor
|
| + ** variables and link the cursor into the BtShared list. */
|
| + pCur->pgnoRoot = (Pgno)iTable;
|
| + pCur->iPage = -1;
|
| + pCur->pKeyInfo = pKeyInfo;
|
| + pCur->pBtree = p;
|
| + pCur->pBt = pBt;
|
| + pCur->curFlags = wrFlag ? BTCF_WriteFlag : 0;
|
| + pCur->curPagerFlags = wrFlag ? 0 : PAGER_GET_READONLY;
|
| + /* If there are two or more cursors on the same btree, then all such
|
| + ** cursors *must* have the BTCF_Multiple flag set. */
|
| + for(pX=pBt->pCursor; pX; pX=pX->pNext){
|
| + if( pX->pgnoRoot==(Pgno)iTable ){
|
| + pX->curFlags |= BTCF_Multiple;
|
| + pCur->curFlags |= BTCF_Multiple;
|
| + }
|
| + }
|
| + pCur->pNext = pBt->pCursor;
|
| + pBt->pCursor = pCur;
|
| + pCur->eState = CURSOR_INVALID;
|
| + return SQLITE_OK;
|
| +}
|
| +int sqlite3BtreeCursor(
|
| + Btree *p, /* The btree */
|
| + int iTable, /* Root page of table to open */
|
| + int wrFlag, /* 1 to write. 0 read-only */
|
| + struct KeyInfo *pKeyInfo, /* First arg to xCompare() */
|
| + BtCursor *pCur /* Write new cursor here */
|
| +){
|
| + int rc;
|
| + if( iTable<1 ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + }else{
|
| + sqlite3BtreeEnter(p);
|
| + rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
|
| + sqlite3BtreeLeave(p);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return the size of a BtCursor object in bytes.
|
| +**
|
| +** This interfaces is needed so that users of cursors can preallocate
|
| +** sufficient storage to hold a cursor. The BtCursor object is opaque
|
| +** to users so they cannot do the sizeof() themselves - they must call
|
| +** this routine.
|
| +*/
|
| +int sqlite3BtreeCursorSize(void){
|
| + return ROUND8(sizeof(BtCursor));
|
| +}
|
| +
|
| +/*
|
| +** Initialize memory that will be converted into a BtCursor object.
|
| +**
|
| +** The simple approach here would be to memset() the entire object
|
| +** to zero. But it turns out that the apPage[] and aiIdx[] arrays
|
| +** do not need to be zeroed and they are large, so we can save a lot
|
| +** of run-time by skipping the initialization of those elements.
|
| +*/
|
| +void sqlite3BtreeCursorZero(BtCursor *p){
|
| + memset(p, 0, offsetof(BtCursor, iPage));
|
| +}
|
| +
|
| +/*
|
| +** Close a cursor. The read lock on the database file is released
|
| +** when the last cursor is closed.
|
| +*/
|
| +int sqlite3BtreeCloseCursor(BtCursor *pCur){
|
| + Btree *pBtree = pCur->pBtree;
|
| + if( pBtree ){
|
| + int i;
|
| + BtShared *pBt = pCur->pBt;
|
| + sqlite3BtreeEnter(pBtree);
|
| + sqlite3BtreeClearCursor(pCur);
|
| + assert( pBt->pCursor!=0 );
|
| + if( pBt->pCursor==pCur ){
|
| + pBt->pCursor = pCur->pNext;
|
| + }else{
|
| + BtCursor *pPrev = pBt->pCursor;
|
| + do{
|
| + if( pPrev->pNext==pCur ){
|
| + pPrev->pNext = pCur->pNext;
|
| + break;
|
| + }
|
| + pPrev = pPrev->pNext;
|
| + }while( ALWAYS(pPrev) );
|
| + }
|
| + for(i=0; i<=pCur->iPage; i++){
|
| + releasePage(pCur->apPage[i]);
|
| + }
|
| + unlockBtreeIfUnused(pBt);
|
| + sqlite3_free(pCur->aOverflow);
|
| + /* sqlite3_free(pCur); */
|
| + sqlite3BtreeLeave(pBtree);
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Make sure the BtCursor* given in the argument has a valid
|
| +** BtCursor.info structure. If it is not already valid, call
|
| +** btreeParseCell() to fill it in.
|
| +**
|
| +** BtCursor.info is a cache of the information in the current cell.
|
| +** Using this cache reduces the number of calls to btreeParseCell().
|
| +*/
|
| +#ifndef NDEBUG
|
| + static void assertCellInfo(BtCursor *pCur){
|
| + CellInfo info;
|
| + int iPage = pCur->iPage;
|
| + memset(&info, 0, sizeof(info));
|
| + btreeParseCell(pCur->apPage[iPage], pCur->aiIdx[iPage], &info);
|
| + assert( CORRUPT_DB || memcmp(&info, &pCur->info, sizeof(info))==0 );
|
| + }
|
| +#else
|
| + #define assertCellInfo(x)
|
| +#endif
|
| +static SQLITE_NOINLINE void getCellInfo(BtCursor *pCur){
|
| + if( pCur->info.nSize==0 ){
|
| + int iPage = pCur->iPage;
|
| + pCur->curFlags |= BTCF_ValidNKey;
|
| + btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);
|
| + }else{
|
| + assertCellInfo(pCur);
|
| + }
|
| +}
|
| +
|
| +#ifndef NDEBUG /* The next routine used only within assert() statements */
|
| +/*
|
| +** Return true if the given BtCursor is valid. A valid cursor is one
|
| +** that is currently pointing to a row in a (non-empty) table.
|
| +** This is a verification routine is used only within assert() statements.
|
| +*/
|
| +int sqlite3BtreeCursorIsValid(BtCursor *pCur){
|
| + return pCur && pCur->eState==CURSOR_VALID;
|
| +}
|
| +#endif /* NDEBUG */
|
| +int sqlite3BtreeCursorIsValidNN(BtCursor *pCur){
|
| + assert( pCur!=0 );
|
| + return pCur->eState==CURSOR_VALID;
|
| +}
|
| +
|
| +/*
|
| +** Return the value of the integer key or "rowid" for a table btree.
|
| +** This routine is only valid for a cursor that is pointing into a
|
| +** ordinary table btree. If the cursor points to an index btree or
|
| +** is invalid, the result of this routine is undefined.
|
| +*/
|
| +i64 sqlite3BtreeIntegerKey(BtCursor *pCur){
|
| + assert( cursorHoldsMutex(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( pCur->curIntKey );
|
| + getCellInfo(pCur);
|
| + return pCur->info.nKey;
|
| +}
|
| +
|
| +/*
|
| +** Return the number of bytes of payload for the entry that pCur is
|
| +** currently pointing to. For table btrees, this will be the amount
|
| +** of data. For index btrees, this will be the size of the key.
|
| +**
|
| +** The caller must guarantee that the cursor is pointing to a non-NULL
|
| +** valid entry. In other words, the calling procedure must guarantee
|
| +** that the cursor has Cursor.eState==CURSOR_VALID.
|
| +*/
|
| +u32 sqlite3BtreePayloadSize(BtCursor *pCur){
|
| + assert( cursorHoldsMutex(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + getCellInfo(pCur);
|
| + return pCur->info.nPayload;
|
| +}
|
| +
|
| +/*
|
| +** Given the page number of an overflow page in the database (parameter
|
| +** ovfl), this function finds the page number of the next page in the
|
| +** linked list of overflow pages. If possible, it uses the auto-vacuum
|
| +** pointer-map data instead of reading the content of page ovfl to do so.
|
| +**
|
| +** If an error occurs an SQLite error code is returned. Otherwise:
|
| +**
|
| +** The page number of the next overflow page in the linked list is
|
| +** written to *pPgnoNext. If page ovfl is the last page in its linked
|
| +** list, *pPgnoNext is set to zero.
|
| +**
|
| +** If ppPage is not NULL, and a reference to the MemPage object corresponding
|
| +** to page number pOvfl was obtained, then *ppPage is set to point to that
|
| +** reference. It is the responsibility of the caller to call releasePage()
|
| +** on *ppPage to free the reference. In no reference was obtained (because
|
| +** the pointer-map was used to obtain the value for *pPgnoNext), then
|
| +** *ppPage is set to zero.
|
| +*/
|
| +static int getOverflowPage(
|
| + BtShared *pBt, /* The database file */
|
| + Pgno ovfl, /* Current overflow page number */
|
| + MemPage **ppPage, /* OUT: MemPage handle (may be NULL) */
|
| + Pgno *pPgnoNext /* OUT: Next overflow page number */
|
| +){
|
| + Pgno next = 0;
|
| + MemPage *pPage = 0;
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert(pPgnoNext);
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + /* Try to find the next page in the overflow list using the
|
| + ** autovacuum pointer-map pages. Guess that the next page in
|
| + ** the overflow list is page number (ovfl+1). If that guess turns
|
| + ** out to be wrong, fall back to loading the data of page
|
| + ** number ovfl to determine the next page number.
|
| + */
|
| + if( pBt->autoVacuum ){
|
| + Pgno pgno;
|
| + Pgno iGuess = ovfl+1;
|
| + u8 eType;
|
| +
|
| + while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
|
| + iGuess++;
|
| + }
|
| +
|
| + if( iGuess<=btreePagecount(pBt) ){
|
| + rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
|
| + if( rc==SQLITE_OK && eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
|
| + next = iGuess;
|
| + rc = SQLITE_DONE;
|
| + }
|
| + }
|
| + }
|
| +#endif
|
| +
|
| + assert( next==0 || rc==SQLITE_DONE );
|
| + if( rc==SQLITE_OK ){
|
| + rc = btreeGetPage(pBt, ovfl, &pPage, (ppPage==0) ? PAGER_GET_READONLY : 0);
|
| + assert( rc==SQLITE_OK || pPage==0 );
|
| + if( rc==SQLITE_OK ){
|
| + next = get4byte(pPage->aData);
|
| + }
|
| + }
|
| +
|
| + *pPgnoNext = next;
|
| + if( ppPage ){
|
| + *ppPage = pPage;
|
| + }else{
|
| + releasePage(pPage);
|
| + }
|
| + return (rc==SQLITE_DONE ? SQLITE_OK : rc);
|
| +}
|
| +
|
| +/*
|
| +** Copy data from a buffer to a page, or from a page to a buffer.
|
| +**
|
| +** pPayload is a pointer to data stored on database page pDbPage.
|
| +** If argument eOp is false, then nByte bytes of data are copied
|
| +** from pPayload to the buffer pointed at by pBuf. If eOp is true,
|
| +** then sqlite3PagerWrite() is called on pDbPage and nByte bytes
|
| +** of data are copied from the buffer pBuf to pPayload.
|
| +**
|
| +** SQLITE_OK is returned on success, otherwise an error code.
|
| +*/
|
| +static int copyPayload(
|
| + void *pPayload, /* Pointer to page data */
|
| + void *pBuf, /* Pointer to buffer */
|
| + int nByte, /* Number of bytes to copy */
|
| + int eOp, /* 0 -> copy from page, 1 -> copy to page */
|
| + DbPage *pDbPage /* Page containing pPayload */
|
| +){
|
| + if( eOp ){
|
| + /* Copy data from buffer to page (a write operation) */
|
| + int rc = sqlite3PagerWrite(pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + memcpy(pPayload, pBuf, nByte);
|
| + }else{
|
| + /* Copy data from page to buffer (a read operation) */
|
| + memcpy(pBuf, pPayload, nByte);
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** This function is used to read or overwrite payload information
|
| +** for the entry that the pCur cursor is pointing to. The eOp
|
| +** argument is interpreted as follows:
|
| +**
|
| +** 0: The operation is a read. Populate the overflow cache.
|
| +** 1: The operation is a write. Populate the overflow cache.
|
| +**
|
| +** A total of "amt" bytes are read or written beginning at "offset".
|
| +** Data is read to or from the buffer pBuf.
|
| +**
|
| +** The content being read or written might appear on the main page
|
| +** or be scattered out on multiple overflow pages.
|
| +**
|
| +** If the current cursor entry uses one or more overflow pages
|
| +** this function may allocate space for and lazily populate
|
| +** the overflow page-list cache array (BtCursor.aOverflow).
|
| +** Subsequent calls use this cache to make seeking to the supplied offset
|
| +** more efficient.
|
| +**
|
| +** Once an overflow page-list cache has been allocated, it must be
|
| +** invalidated if some other cursor writes to the same table, or if
|
| +** the cursor is moved to a different row. Additionally, in auto-vacuum
|
| +** mode, the following events may invalidate an overflow page-list cache.
|
| +**
|
| +** * An incremental vacuum,
|
| +** * A commit in auto_vacuum="full" mode,
|
| +** * Creating a table (may require moving an overflow page).
|
| +*/
|
| +static int accessPayload(
|
| + BtCursor *pCur, /* Cursor pointing to entry to read from */
|
| + u32 offset, /* Begin reading this far into payload */
|
| + u32 amt, /* Read this many bytes */
|
| + unsigned char *pBuf, /* Write the bytes into this buffer */
|
| + int eOp /* zero to read. non-zero to write. */
|
| +){
|
| + unsigned char *aPayload;
|
| + int rc = SQLITE_OK;
|
| + int iIdx = 0;
|
| + MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
|
| + BtShared *pBt = pCur->pBt; /* Btree this cursor belongs to */
|
| +#ifdef SQLITE_DIRECT_OVERFLOW_READ
|
| + unsigned char * const pBufStart = pBuf; /* Start of original out buffer */
|
| +#endif
|
| +
|
| + assert( pPage );
|
| + assert( eOp==0 || eOp==1 );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
|
| + assert( cursorHoldsMutex(pCur) );
|
| +
|
| + getCellInfo(pCur);
|
| + aPayload = pCur->info.pPayload;
|
| + assert( offset+amt <= pCur->info.nPayload );
|
| +
|
| + assert( aPayload > pPage->aData );
|
| + if( (uptr)(aPayload - pPage->aData) > (pBt->usableSize - pCur->info.nLocal) ){
|
| + /* Trying to read or write past the end of the data is an error. The
|
| + ** conditional above is really:
|
| + ** &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
|
| + ** but is recast into its current form to avoid integer overflow problems
|
| + */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| +
|
| + /* Check if data must be read/written to/from the btree page itself. */
|
| + if( offset<pCur->info.nLocal ){
|
| + int a = amt;
|
| + if( a+offset>pCur->info.nLocal ){
|
| + a = pCur->info.nLocal - offset;
|
| + }
|
| + rc = copyPayload(&aPayload[offset], pBuf, a, eOp, pPage->pDbPage);
|
| + offset = 0;
|
| + pBuf += a;
|
| + amt -= a;
|
| + }else{
|
| + offset -= pCur->info.nLocal;
|
| + }
|
| +
|
| +
|
| + if( rc==SQLITE_OK && amt>0 ){
|
| + const u32 ovflSize = pBt->usableSize - 4; /* Bytes content per ovfl page */
|
| + Pgno nextPage;
|
| +
|
| + nextPage = get4byte(&aPayload[pCur->info.nLocal]);
|
| +
|
| + /* If the BtCursor.aOverflow[] has not been allocated, allocate it now.
|
| + **
|
| + ** The aOverflow[] array is sized at one entry for each overflow page
|
| + ** in the overflow chain. The page number of the first overflow page is
|
| + ** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array
|
| + ** means "not yet known" (the cache is lazily populated).
|
| + */
|
| + if( (pCur->curFlags & BTCF_ValidOvfl)==0 ){
|
| + int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize;
|
| + if( nOvfl>pCur->nOvflAlloc ){
|
| + Pgno *aNew = (Pgno*)sqlite3Realloc(
|
| + pCur->aOverflow, nOvfl*2*sizeof(Pgno)
|
| + );
|
| + if( aNew==0 ){
|
| + return SQLITE_NOMEM_BKPT;
|
| + }else{
|
| + pCur->nOvflAlloc = nOvfl*2;
|
| + pCur->aOverflow = aNew;
|
| + }
|
| + }
|
| + memset(pCur->aOverflow, 0, nOvfl*sizeof(Pgno));
|
| + pCur->curFlags |= BTCF_ValidOvfl;
|
| + }else{
|
| + /* If the overflow page-list cache has been allocated and the
|
| + ** entry for the first required overflow page is valid, skip
|
| + ** directly to it.
|
| + */
|
| + if( pCur->aOverflow[offset/ovflSize] ){
|
| + iIdx = (offset/ovflSize);
|
| + nextPage = pCur->aOverflow[iIdx];
|
| + offset = (offset%ovflSize);
|
| + }
|
| + }
|
| +
|
| + assert( rc==SQLITE_OK && amt>0 );
|
| + while( nextPage ){
|
| + /* If required, populate the overflow page-list cache. */
|
| + assert( pCur->aOverflow[iIdx]==0
|
| + || pCur->aOverflow[iIdx]==nextPage
|
| + || CORRUPT_DB );
|
| + pCur->aOverflow[iIdx] = nextPage;
|
| +
|
| + if( offset>=ovflSize ){
|
| + /* The only reason to read this page is to obtain the page
|
| + ** number for the next page in the overflow chain. The page
|
| + ** data is not required. So first try to lookup the overflow
|
| + ** page-list cache, if any, then fall back to the getOverflowPage()
|
| + ** function.
|
| + */
|
| + assert( pCur->curFlags & BTCF_ValidOvfl );
|
| + assert( pCur->pBtree->db==pBt->db );
|
| + if( pCur->aOverflow[iIdx+1] ){
|
| + nextPage = pCur->aOverflow[iIdx+1];
|
| + }else{
|
| + rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
|
| + }
|
| + offset -= ovflSize;
|
| + }else{
|
| + /* Need to read this page properly. It contains some of the
|
| + ** range of data that is being read (eOp==0) or written (eOp!=0).
|
| + */
|
| +#ifdef SQLITE_DIRECT_OVERFLOW_READ
|
| + sqlite3_file *fd; /* File from which to do direct overflow read */
|
| +#endif
|
| + int a = amt;
|
| + if( a + offset > ovflSize ){
|
| + a = ovflSize - offset;
|
| + }
|
| +
|
| +#ifdef SQLITE_DIRECT_OVERFLOW_READ
|
| + /* If all the following are true:
|
| + **
|
| + ** 1) this is a read operation, and
|
| + ** 2) data is required from the start of this overflow page, and
|
| + ** 3) there is no open write-transaction, and
|
| + ** 4) the database is file-backed, and
|
| + ** 5) the page is not in the WAL file
|
| + ** 6) at least 4 bytes have already been read into the output buffer
|
| + **
|
| + ** then data can be read directly from the database file into the
|
| + ** output buffer, bypassing the page-cache altogether. This speeds
|
| + ** up loading large records that span many overflow pages.
|
| + */
|
| + if( eOp==0 /* (1) */
|
| + && offset==0 /* (2) */
|
| + && pBt->inTransaction==TRANS_READ /* (3) */
|
| + && (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (4) */
|
| + && 0==sqlite3PagerUseWal(pBt->pPager, nextPage) /* (5) */
|
| + && &pBuf[-4]>=pBufStart /* (6) */
|
| + ){
|
| + u8 aSave[4];
|
| + u8 *aWrite = &pBuf[-4];
|
| + assert( aWrite>=pBufStart ); /* due to (6) */
|
| + memcpy(aSave, aWrite, 4);
|
| + rc = sqlite3OsRead(fd, aWrite, a+4, (i64)pBt->pageSize*(nextPage-1));
|
| + nextPage = get4byte(aWrite);
|
| + memcpy(aWrite, aSave, 4);
|
| + }else
|
| +#endif
|
| +
|
| + {
|
| + DbPage *pDbPage;
|
| + rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage,
|
| + (eOp==0 ? PAGER_GET_READONLY : 0)
|
| + );
|
| + if( rc==SQLITE_OK ){
|
| + aPayload = sqlite3PagerGetData(pDbPage);
|
| + nextPage = get4byte(aPayload);
|
| + rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
|
| + sqlite3PagerUnref(pDbPage);
|
| + offset = 0;
|
| + }
|
| + }
|
| + amt -= a;
|
| + if( amt==0 ) return rc;
|
| + pBuf += a;
|
| + }
|
| + if( rc ) break;
|
| + iIdx++;
|
| + }
|
| + }
|
| +
|
| + if( rc==SQLITE_OK && amt>0 ){
|
| + return SQLITE_CORRUPT_BKPT; /* Overflow chain ends prematurely */
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Read part of the payload for the row at which that cursor pCur is currently
|
| +** pointing. "amt" bytes will be transferred into pBuf[]. The transfer
|
| +** begins at "offset".
|
| +**
|
| +** pCur can be pointing to either a table or an index b-tree.
|
| +** If pointing to a table btree, then the content section is read. If
|
| +** pCur is pointing to an index b-tree then the key section is read.
|
| +**
|
| +** For sqlite3BtreePayload(), the caller must ensure that pCur is pointing
|
| +** to a valid row in the table. For sqlite3BtreePayloadChecked(), the
|
| +** cursor might be invalid or might need to be restored before being read.
|
| +**
|
| +** Return SQLITE_OK on success or an error code if anything goes
|
| +** wrong. An error is returned if "offset+amt" is larger than
|
| +** the available payload.
|
| +*/
|
| +int sqlite3BtreePayload(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
|
| + assert( cursorHoldsMutex(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
|
| + assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
|
| + return accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
|
| +}
|
| +
|
| +/*
|
| +** This variant of sqlite3BtreePayload() works even if the cursor has not
|
| +** in the CURSOR_VALID state. It is only used by the sqlite3_blob_read()
|
| +** interface.
|
| +*/
|
| +#ifndef SQLITE_OMIT_INCRBLOB
|
| +static SQLITE_NOINLINE int accessPayloadChecked(
|
| + BtCursor *pCur,
|
| + u32 offset,
|
| + u32 amt,
|
| + void *pBuf
|
| +){
|
| + int rc;
|
| + if ( pCur->eState==CURSOR_INVALID ){
|
| + return SQLITE_ABORT;
|
| + }
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + rc = btreeRestoreCursorPosition(pCur);
|
| + return rc ? rc : accessPayload(pCur, offset, amt, pBuf, 0);
|
| +}
|
| +int sqlite3BtreePayloadChecked(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
|
| + if( pCur->eState==CURSOR_VALID ){
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + return accessPayload(pCur, offset, amt, pBuf, 0);
|
| + }else{
|
| + return accessPayloadChecked(pCur, offset, amt, pBuf);
|
| + }
|
| +}
|
| +#endif /* SQLITE_OMIT_INCRBLOB */
|
| +
|
| +/*
|
| +** Return a pointer to payload information from the entry that the
|
| +** pCur cursor is pointing to. The pointer is to the beginning of
|
| +** the key if index btrees (pPage->intKey==0) and is the data for
|
| +** table btrees (pPage->intKey==1). The number of bytes of available
|
| +** key/data is written into *pAmt. If *pAmt==0, then the value
|
| +** returned will not be a valid pointer.
|
| +**
|
| +** This routine is an optimization. It is common for the entire key
|
| +** and data to fit on the local page and for there to be no overflow
|
| +** pages. When that is so, this routine can be used to access the
|
| +** key and data without making a copy. If the key and/or data spills
|
| +** onto overflow pages, then accessPayload() must be used to reassemble
|
| +** the key/data and copy it into a preallocated buffer.
|
| +**
|
| +** The pointer returned by this routine looks directly into the cached
|
| +** page of the database. The data might change or move the next time
|
| +** any btree routine is called.
|
| +*/
|
| +static const void *fetchPayload(
|
| + BtCursor *pCur, /* Cursor pointing to entry to read from */
|
| + u32 *pAmt /* Write the number of available bytes here */
|
| +){
|
| + u32 amt;
|
| + assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
|
| + assert( pCur->info.nSize>0 );
|
| + assert( pCur->info.pPayload>pCur->apPage[pCur->iPage]->aData || CORRUPT_DB );
|
| + assert( pCur->info.pPayload<pCur->apPage[pCur->iPage]->aDataEnd ||CORRUPT_DB);
|
| + amt = (int)(pCur->apPage[pCur->iPage]->aDataEnd - pCur->info.pPayload);
|
| + if( pCur->info.nLocal<amt ) amt = pCur->info.nLocal;
|
| + *pAmt = amt;
|
| + return (void*)pCur->info.pPayload;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** For the entry that cursor pCur is point to, return as
|
| +** many bytes of the key or data as are available on the local
|
| +** b-tree page. Write the number of available bytes into *pAmt.
|
| +**
|
| +** The pointer returned is ephemeral. The key/data may move
|
| +** or be destroyed on the next call to any Btree routine,
|
| +** including calls from other threads against the same cache.
|
| +** Hence, a mutex on the BtShared should be held prior to calling
|
| +** this routine.
|
| +**
|
| +** These routines is used to get quick access to key and data
|
| +** in the common case where no overflow pages are used.
|
| +*/
|
| +const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){
|
| + return fetchPayload(pCur, pAmt);
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Move the cursor down to a new child page. The newPgno argument is the
|
| +** page number of the child page to move to.
|
| +**
|
| +** This function returns SQLITE_CORRUPT if the page-header flags field of
|
| +** the new child page does not match the flags field of the parent (i.e.
|
| +** if an intkey page appears to be the parent of a non-intkey page, or
|
| +** vice-versa).
|
| +*/
|
| +static int moveToChild(BtCursor *pCur, u32 newPgno){
|
| + BtShared *pBt = pCur->pBt;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
|
| + assert( pCur->iPage>=0 );
|
| + if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + pCur->info.nSize = 0;
|
| + pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
|
| + pCur->iPage++;
|
| + pCur->aiIdx[pCur->iPage] = 0;
|
| + return getAndInitPage(pBt, newPgno, &pCur->apPage[pCur->iPage],
|
| + pCur, pCur->curPagerFlags);
|
| +}
|
| +
|
| +#if SQLITE_DEBUG
|
| +/*
|
| +** Page pParent is an internal (non-leaf) tree page. This function
|
| +** asserts that page number iChild is the left-child if the iIdx'th
|
| +** cell in page pParent. Or, if iIdx is equal to the total number of
|
| +** cells in pParent, that page number iChild is the right-child of
|
| +** the page.
|
| +*/
|
| +static void assertParentIndex(MemPage *pParent, int iIdx, Pgno iChild){
|
| + if( CORRUPT_DB ) return; /* The conditions tested below might not be true
|
| + ** in a corrupt database */
|
| + assert( iIdx<=pParent->nCell );
|
| + if( iIdx==pParent->nCell ){
|
| + assert( get4byte(&pParent->aData[pParent->hdrOffset+8])==iChild );
|
| + }else{
|
| + assert( get4byte(findCell(pParent, iIdx))==iChild );
|
| + }
|
| +}
|
| +#else
|
| +# define assertParentIndex(x,y,z)
|
| +#endif
|
| +
|
| +/*
|
| +** Move the cursor up to the parent page.
|
| +**
|
| +** pCur->idx is set to the cell index that contains the pointer
|
| +** to the page we are coming from. If we are coming from the
|
| +** right-most child page then pCur->idx is set to one more than
|
| +** the largest cell index.
|
| +*/
|
| +static void moveToParent(BtCursor *pCur){
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( pCur->iPage>0 );
|
| + assert( pCur->apPage[pCur->iPage] );
|
| + assertParentIndex(
|
| + pCur->apPage[pCur->iPage-1],
|
| + pCur->aiIdx[pCur->iPage-1],
|
| + pCur->apPage[pCur->iPage]->pgno
|
| + );
|
| + testcase( pCur->aiIdx[pCur->iPage-1] > pCur->apPage[pCur->iPage-1]->nCell );
|
| + pCur->info.nSize = 0;
|
| + pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
|
| + releasePageNotNull(pCur->apPage[pCur->iPage--]);
|
| +}
|
| +
|
| +/*
|
| +** Move the cursor to point to the root page of its b-tree structure.
|
| +**
|
| +** If the table has a virtual root page, then the cursor is moved to point
|
| +** to the virtual root page instead of the actual root page. A table has a
|
| +** virtual root page when the actual root page contains no cells and a
|
| +** single child page. This can only happen with the table rooted at page 1.
|
| +**
|
| +** If the b-tree structure is empty, the cursor state is set to
|
| +** CURSOR_INVALID. Otherwise, the cursor is set to point to the first
|
| +** cell located on the root (or virtual root) page and the cursor state
|
| +** is set to CURSOR_VALID.
|
| +**
|
| +** If this function returns successfully, it may be assumed that the
|
| +** page-header flags indicate that the [virtual] root-page is the expected
|
| +** kind of b-tree page (i.e. if when opening the cursor the caller did not
|
| +** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D,
|
| +** indicating a table b-tree, or if the caller did specify a KeyInfo
|
| +** structure the flags byte is set to 0x02 or 0x0A, indicating an index
|
| +** b-tree).
|
| +*/
|
| +static int moveToRoot(BtCursor *pCur){
|
| + MemPage *pRoot;
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
|
| + assert( CURSOR_VALID < CURSOR_REQUIRESEEK );
|
| + assert( CURSOR_FAULT > CURSOR_REQUIRESEEK );
|
| + if( pCur->eState>=CURSOR_REQUIRESEEK ){
|
| + if( pCur->eState==CURSOR_FAULT ){
|
| + assert( pCur->skipNext!=SQLITE_OK );
|
| + return pCur->skipNext;
|
| + }
|
| + sqlite3BtreeClearCursor(pCur);
|
| + }
|
| +
|
| + if( pCur->iPage>=0 ){
|
| + if( pCur->iPage ){
|
| + do{
|
| + assert( pCur->apPage[pCur->iPage]!=0 );
|
| + releasePageNotNull(pCur->apPage[pCur->iPage--]);
|
| + }while( pCur->iPage);
|
| + goto skip_init;
|
| + }
|
| + }else if( pCur->pgnoRoot==0 ){
|
| + pCur->eState = CURSOR_INVALID;
|
| + return SQLITE_OK;
|
| + }else{
|
| + assert( pCur->iPage==(-1) );
|
| + rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->apPage[0],
|
| + 0, pCur->curPagerFlags);
|
| + if( rc!=SQLITE_OK ){
|
| + pCur->eState = CURSOR_INVALID;
|
| + return rc;
|
| + }
|
| + pCur->iPage = 0;
|
| + pCur->curIntKey = pCur->apPage[0]->intKey;
|
| + }
|
| + pRoot = pCur->apPage[0];
|
| + assert( pRoot->pgno==pCur->pgnoRoot );
|
| +
|
| + /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor
|
| + ** expected to open it on an index b-tree. Otherwise, if pKeyInfo is
|
| + ** NULL, the caller expects a table b-tree. If this is not the case,
|
| + ** return an SQLITE_CORRUPT error.
|
| + **
|
| + ** Earlier versions of SQLite assumed that this test could not fail
|
| + ** if the root page was already loaded when this function was called (i.e.
|
| + ** if pCur->iPage>=0). But this is not so if the database is corrupted
|
| + ** in such a way that page pRoot is linked into a second b-tree table
|
| + ** (or the freelist). */
|
| + assert( pRoot->intKey==1 || pRoot->intKey==0 );
|
| + if( pRoot->isInit==0 || (pCur->pKeyInfo==0)!=pRoot->intKey ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| +
|
| +skip_init:
|
| + pCur->aiIdx[0] = 0;
|
| + pCur->info.nSize = 0;
|
| + pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidNKey|BTCF_ValidOvfl);
|
| +
|
| + pRoot = pCur->apPage[0];
|
| + if( pRoot->nCell>0 ){
|
| + pCur->eState = CURSOR_VALID;
|
| + }else if( !pRoot->leaf ){
|
| + Pgno subpage;
|
| + if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
|
| + subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
|
| + pCur->eState = CURSOR_VALID;
|
| + rc = moveToChild(pCur, subpage);
|
| + }else{
|
| + pCur->eState = CURSOR_INVALID;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Move the cursor down to the left-most leaf entry beneath the
|
| +** entry to which it is currently pointing.
|
| +**
|
| +** The left-most leaf is the one with the smallest key - the first
|
| +** in ascending order.
|
| +*/
|
| +static int moveToLeftmost(BtCursor *pCur){
|
| + Pgno pgno;
|
| + int rc = SQLITE_OK;
|
| + MemPage *pPage;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
|
| + assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
|
| + pgno = get4byte(findCell(pPage, pCur->aiIdx[pCur->iPage]));
|
| + rc = moveToChild(pCur, pgno);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Move the cursor down to the right-most leaf entry beneath the
|
| +** page to which it is currently pointing. Notice the difference
|
| +** between moveToLeftmost() and moveToRightmost(). moveToLeftmost()
|
| +** finds the left-most entry beneath the *entry* whereas moveToRightmost()
|
| +** finds the right-most entry beneath the *page*.
|
| +**
|
| +** The right-most entry is the one with the largest key - the last
|
| +** key in ascending order.
|
| +*/
|
| +static int moveToRightmost(BtCursor *pCur){
|
| + Pgno pgno;
|
| + int rc = SQLITE_OK;
|
| + MemPage *pPage = 0;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + while( !(pPage = pCur->apPage[pCur->iPage])->leaf ){
|
| + pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
|
| + pCur->aiIdx[pCur->iPage] = pPage->nCell;
|
| + rc = moveToChild(pCur, pgno);
|
| + if( rc ) return rc;
|
| + }
|
| + pCur->aiIdx[pCur->iPage] = pPage->nCell-1;
|
| + assert( pCur->info.nSize==0 );
|
| + assert( (pCur->curFlags & BTCF_ValidNKey)==0 );
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/* Move the cursor to the first entry in the table. Return SQLITE_OK
|
| +** on success. Set *pRes to 0 if the cursor actually points to something
|
| +** or set *pRes to 1 if the table is empty.
|
| +*/
|
| +int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
|
| + int rc;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
|
| + rc = moveToRoot(pCur);
|
| + if( rc==SQLITE_OK ){
|
| + if( pCur->eState==CURSOR_INVALID ){
|
| + assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
|
| + *pRes = 1;
|
| + }else{
|
| + assert( pCur->apPage[pCur->iPage]->nCell>0 );
|
| + *pRes = 0;
|
| + rc = moveToLeftmost(pCur);
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/* Move the cursor to the last entry in the table. Return SQLITE_OK
|
| +** on success. Set *pRes to 0 if the cursor actually points to something
|
| +** or set *pRes to 1 if the table is empty.
|
| +*/
|
| +int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
|
| + int rc;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
|
| +
|
| + /* If the cursor already points to the last entry, this is a no-op. */
|
| + if( CURSOR_VALID==pCur->eState && (pCur->curFlags & BTCF_AtLast)!=0 ){
|
| +#ifdef SQLITE_DEBUG
|
| + /* This block serves to assert() that the cursor really does point
|
| + ** to the last entry in the b-tree. */
|
| + int ii;
|
| + for(ii=0; ii<pCur->iPage; ii++){
|
| + assert( pCur->aiIdx[ii]==pCur->apPage[ii]->nCell );
|
| + }
|
| + assert( pCur->aiIdx[pCur->iPage]==pCur->apPage[pCur->iPage]->nCell-1 );
|
| + assert( pCur->apPage[pCur->iPage]->leaf );
|
| +#endif
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + rc = moveToRoot(pCur);
|
| + if( rc==SQLITE_OK ){
|
| + if( CURSOR_INVALID==pCur->eState ){
|
| + assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
|
| + *pRes = 1;
|
| + }else{
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + *pRes = 0;
|
| + rc = moveToRightmost(pCur);
|
| + if( rc==SQLITE_OK ){
|
| + pCur->curFlags |= BTCF_AtLast;
|
| + }else{
|
| + pCur->curFlags &= ~BTCF_AtLast;
|
| + }
|
| +
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/* Move the cursor so that it points to an entry near the key
|
| +** specified by pIdxKey or intKey. Return a success code.
|
| +**
|
| +** For INTKEY tables, the intKey parameter is used. pIdxKey
|
| +** must be NULL. For index tables, pIdxKey is used and intKey
|
| +** is ignored.
|
| +**
|
| +** If an exact match is not found, then the cursor is always
|
| +** left pointing at a leaf page which would hold the entry if it
|
| +** were present. The cursor might point to an entry that comes
|
| +** before or after the key.
|
| +**
|
| +** An integer is written into *pRes which is the result of
|
| +** comparing the key with the entry to which the cursor is
|
| +** pointing. The meaning of the integer written into
|
| +** *pRes is as follows:
|
| +**
|
| +** *pRes<0 The cursor is left pointing at an entry that
|
| +** is smaller than intKey/pIdxKey or if the table is empty
|
| +** and the cursor is therefore left point to nothing.
|
| +**
|
| +** *pRes==0 The cursor is left pointing at an entry that
|
| +** exactly matches intKey/pIdxKey.
|
| +**
|
| +** *pRes>0 The cursor is left pointing at an entry that
|
| +** is larger than intKey/pIdxKey.
|
| +**
|
| +** For index tables, the pIdxKey->eqSeen field is set to 1 if there
|
| +** exists an entry in the table that exactly matches pIdxKey.
|
| +*/
|
| +int sqlite3BtreeMovetoUnpacked(
|
| + BtCursor *pCur, /* The cursor to be moved */
|
| + UnpackedRecord *pIdxKey, /* Unpacked index key */
|
| + i64 intKey, /* The table key */
|
| + int biasRight, /* If true, bias the search to the high end */
|
| + int *pRes /* Write search results here */
|
| +){
|
| + int rc;
|
| + RecordCompare xRecordCompare;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
|
| + assert( pRes );
|
| + assert( (pIdxKey==0)==(pCur->pKeyInfo==0) );
|
| + assert( pCur->eState!=CURSOR_VALID || (pIdxKey==0)==(pCur->curIntKey!=0) );
|
| +
|
| + /* If the cursor is already positioned at the point we are trying
|
| + ** to move to, then just return without doing any work */
|
| + if( pIdxKey==0
|
| + && pCur->eState==CURSOR_VALID && (pCur->curFlags & BTCF_ValidNKey)!=0
|
| + ){
|
| + if( pCur->info.nKey==intKey ){
|
| + *pRes = 0;
|
| + return SQLITE_OK;
|
| + }
|
| + if( pCur->info.nKey<intKey ){
|
| + if( (pCur->curFlags & BTCF_AtLast)!=0 ){
|
| + *pRes = -1;
|
| + return SQLITE_OK;
|
| + }
|
| + /* If the requested key is one more than the previous key, then
|
| + ** try to get there using sqlite3BtreeNext() rather than a full
|
| + ** binary search. This is an optimization only. The correct answer
|
| + ** is still obtained without this ase, only a little more slowely */
|
| + if( pCur->info.nKey+1==intKey && !pCur->skipNext ){
|
| + *pRes = 0;
|
| + rc = sqlite3BtreeNext(pCur, pRes);
|
| + if( rc ) return rc;
|
| + if( *pRes==0 ){
|
| + getCellInfo(pCur);
|
| + if( pCur->info.nKey==intKey ){
|
| + return SQLITE_OK;
|
| + }
|
| + }
|
| + }
|
| + }
|
| + }
|
| +
|
| + if( pIdxKey ){
|
| + xRecordCompare = sqlite3VdbeFindCompare(pIdxKey);
|
| + pIdxKey->errCode = 0;
|
| + assert( pIdxKey->default_rc==1
|
| + || pIdxKey->default_rc==0
|
| + || pIdxKey->default_rc==-1
|
| + );
|
| + }else{
|
| + xRecordCompare = 0; /* All keys are integers */
|
| + }
|
| +
|
| + rc = moveToRoot(pCur);
|
| + if( rc ){
|
| + return rc;
|
| + }
|
| + assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );
|
| + assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->isInit );
|
| + assert( pCur->eState==CURSOR_INVALID || pCur->apPage[pCur->iPage]->nCell>0 );
|
| + if( pCur->eState==CURSOR_INVALID ){
|
| + *pRes = -1;
|
| + assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->nCell==0 );
|
| + return SQLITE_OK;
|
| + }
|
| + assert( pCur->apPage[0]->intKey==pCur->curIntKey );
|
| + assert( pCur->curIntKey || pIdxKey );
|
| + for(;;){
|
| + int lwr, upr, idx, c;
|
| + Pgno chldPg;
|
| + MemPage *pPage = pCur->apPage[pCur->iPage];
|
| + u8 *pCell; /* Pointer to current cell in pPage */
|
| +
|
| + /* pPage->nCell must be greater than zero. If this is the root-page
|
| + ** the cursor would have been INVALID above and this for(;;) loop
|
| + ** not run. If this is not the root-page, then the moveToChild() routine
|
| + ** would have already detected db corruption. Similarly, pPage must
|
| + ** be the right kind (index or table) of b-tree page. Otherwise
|
| + ** a moveToChild() or moveToRoot() call would have detected corruption. */
|
| + assert( pPage->nCell>0 );
|
| + assert( pPage->intKey==(pIdxKey==0) );
|
| + lwr = 0;
|
| + upr = pPage->nCell-1;
|
| + assert( biasRight==0 || biasRight==1 );
|
| + idx = upr>>(1-biasRight); /* idx = biasRight ? upr : (lwr+upr)/2; */
|
| + pCur->aiIdx[pCur->iPage] = (u16)idx;
|
| + if( xRecordCompare==0 ){
|
| + for(;;){
|
| + i64 nCellKey;
|
| + pCell = findCellPastPtr(pPage, idx);
|
| + if( pPage->intKeyLeaf ){
|
| + while( 0x80 <= *(pCell++) ){
|
| + if( pCell>=pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + }
|
| + getVarint(pCell, (u64*)&nCellKey);
|
| + if( nCellKey<intKey ){
|
| + lwr = idx+1;
|
| + if( lwr>upr ){ c = -1; break; }
|
| + }else if( nCellKey>intKey ){
|
| + upr = idx-1;
|
| + if( lwr>upr ){ c = +1; break; }
|
| + }else{
|
| + assert( nCellKey==intKey );
|
| + pCur->aiIdx[pCur->iPage] = (u16)idx;
|
| + if( !pPage->leaf ){
|
| + lwr = idx;
|
| + goto moveto_next_layer;
|
| + }else{
|
| + pCur->curFlags |= BTCF_ValidNKey;
|
| + pCur->info.nKey = nCellKey;
|
| + pCur->info.nSize = 0;
|
| + *pRes = 0;
|
| + return SQLITE_OK;
|
| + }
|
| + }
|
| + assert( lwr+upr>=0 );
|
| + idx = (lwr+upr)>>1; /* idx = (lwr+upr)/2; */
|
| + }
|
| + }else{
|
| + for(;;){
|
| + int nCell; /* Size of the pCell cell in bytes */
|
| + pCell = findCellPastPtr(pPage, idx);
|
| +
|
| + /* The maximum supported page-size is 65536 bytes. This means that
|
| + ** the maximum number of record bytes stored on an index B-Tree
|
| + ** page is less than 16384 bytes and may be stored as a 2-byte
|
| + ** varint. This information is used to attempt to avoid parsing
|
| + ** the entire cell by checking for the cases where the record is
|
| + ** stored entirely within the b-tree page by inspecting the first
|
| + ** 2 bytes of the cell.
|
| + */
|
| + nCell = pCell[0];
|
| + if( nCell<=pPage->max1bytePayload ){
|
| + /* This branch runs if the record-size field of the cell is a
|
| + ** single byte varint and the record fits entirely on the main
|
| + ** b-tree page. */
|
| + testcase( pCell+nCell+1==pPage->aDataEnd );
|
| + c = xRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
|
| + }else if( !(pCell[1] & 0x80)
|
| + && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
|
| + ){
|
| + /* The record-size field is a 2 byte varint and the record
|
| + ** fits entirely on the main b-tree page. */
|
| + testcase( pCell+nCell+2==pPage->aDataEnd );
|
| + c = xRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
|
| + }else{
|
| + /* The record flows over onto one or more overflow pages. In
|
| + ** this case the whole cell needs to be parsed, a buffer allocated
|
| + ** and accessPayload() used to retrieve the record into the
|
| + ** buffer before VdbeRecordCompare() can be called.
|
| + **
|
| + ** If the record is corrupt, the xRecordCompare routine may read
|
| + ** up to two varints past the end of the buffer. An extra 18
|
| + ** bytes of padding is allocated at the end of the buffer in
|
| + ** case this happens. */
|
| + void *pCellKey;
|
| + u8 * const pCellBody = pCell - pPage->childPtrSize;
|
| + pPage->xParseCell(pPage, pCellBody, &pCur->info);
|
| + nCell = (int)pCur->info.nKey;
|
| + testcase( nCell<0 ); /* True if key size is 2^32 or more */
|
| + testcase( nCell==0 ); /* Invalid key size: 0x80 0x80 0x00 */
|
| + testcase( nCell==1 ); /* Invalid key size: 0x80 0x80 0x01 */
|
| + testcase( nCell==2 ); /* Minimum legal index key size */
|
| + if( nCell<2 ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto moveto_finish;
|
| + }
|
| + pCellKey = sqlite3Malloc( nCell+18 );
|
| + if( pCellKey==0 ){
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + goto moveto_finish;
|
| + }
|
| + pCur->aiIdx[pCur->iPage] = (u16)idx;
|
| + rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 0);
|
| + pCur->curFlags &= ~BTCF_ValidOvfl;
|
| + if( rc ){
|
| + sqlite3_free(pCellKey);
|
| + goto moveto_finish;
|
| + }
|
| + c = xRecordCompare(nCell, pCellKey, pIdxKey);
|
| + sqlite3_free(pCellKey);
|
| + }
|
| + assert(
|
| + (pIdxKey->errCode!=SQLITE_CORRUPT || c==0)
|
| + && (pIdxKey->errCode!=SQLITE_NOMEM || pCur->pBtree->db->mallocFailed)
|
| + );
|
| + if( c<0 ){
|
| + lwr = idx+1;
|
| + }else if( c>0 ){
|
| + upr = idx-1;
|
| + }else{
|
| + assert( c==0 );
|
| + *pRes = 0;
|
| + rc = SQLITE_OK;
|
| + pCur->aiIdx[pCur->iPage] = (u16)idx;
|
| + if( pIdxKey->errCode ) rc = SQLITE_CORRUPT;
|
| + goto moveto_finish;
|
| + }
|
| + if( lwr>upr ) break;
|
| + assert( lwr+upr>=0 );
|
| + idx = (lwr+upr)>>1; /* idx = (lwr+upr)/2 */
|
| + }
|
| + }
|
| + assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) );
|
| + assert( pPage->isInit );
|
| + if( pPage->leaf ){
|
| + assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
|
| + pCur->aiIdx[pCur->iPage] = (u16)idx;
|
| + *pRes = c;
|
| + rc = SQLITE_OK;
|
| + goto moveto_finish;
|
| + }
|
| +moveto_next_layer:
|
| + if( lwr>=pPage->nCell ){
|
| + chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
|
| + }else{
|
| + chldPg = get4byte(findCell(pPage, lwr));
|
| + }
|
| + pCur->aiIdx[pCur->iPage] = (u16)lwr;
|
| + rc = moveToChild(pCur, chldPg);
|
| + if( rc ) break;
|
| + }
|
| +moveto_finish:
|
| + pCur->info.nSize = 0;
|
| + assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Return TRUE if the cursor is not pointing at an entry of the table.
|
| +**
|
| +** TRUE will be returned after a call to sqlite3BtreeNext() moves
|
| +** past the last entry in the table or sqlite3BtreePrev() moves past
|
| +** the first entry. TRUE is also returned if the table is empty.
|
| +*/
|
| +int sqlite3BtreeEof(BtCursor *pCur){
|
| + /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
|
| + ** have been deleted? This API will need to change to return an error code
|
| + ** as well as the boolean result value.
|
| + */
|
| + return (CURSOR_VALID!=pCur->eState);
|
| +}
|
| +
|
| +/*
|
| +** Advance the cursor to the next entry in the database. If
|
| +** successful then set *pRes=0. If the cursor
|
| +** was already pointing to the last entry in the database before
|
| +** this routine was called, then set *pRes=1.
|
| +**
|
| +** The main entry point is sqlite3BtreeNext(). That routine is optimized
|
| +** for the common case of merely incrementing the cell counter BtCursor.aiIdx
|
| +** to the next cell on the current page. The (slower) btreeNext() helper
|
| +** routine is called when it is necessary to move to a different page or
|
| +** to restore the cursor.
|
| +**
|
| +** The calling function will set *pRes to 0 or 1. The initial *pRes value
|
| +** will be 1 if the cursor being stepped corresponds to an SQL index and
|
| +** if this routine could have been skipped if that SQL index had been
|
| +** a unique index. Otherwise the caller will have set *pRes to zero.
|
| +** Zero is the common case. The btree implementation is free to use the
|
| +** initial *pRes value as a hint to improve performance, but the current
|
| +** SQLite btree implementation does not. (Note that the comdb2 btree
|
| +** implementation does use this hint, however.)
|
| +*/
|
| +static SQLITE_NOINLINE int btreeNext(BtCursor *pCur, int *pRes){
|
| + int rc;
|
| + int idx;
|
| + MemPage *pPage;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
|
| + assert( *pRes==0 );
|
| + if( pCur->eState!=CURSOR_VALID ){
|
| + assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
|
| + rc = restoreCursorPosition(pCur);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + if( CURSOR_INVALID==pCur->eState ){
|
| + *pRes = 1;
|
| + return SQLITE_OK;
|
| + }
|
| + if( pCur->skipNext ){
|
| + assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
|
| + pCur->eState = CURSOR_VALID;
|
| + if( pCur->skipNext>0 ){
|
| + pCur->skipNext = 0;
|
| + return SQLITE_OK;
|
| + }
|
| + pCur->skipNext = 0;
|
| + }
|
| + }
|
| +
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + idx = ++pCur->aiIdx[pCur->iPage];
|
| + assert( pPage->isInit );
|
| +
|
| + /* If the database file is corrupt, it is possible for the value of idx
|
| + ** to be invalid here. This can only occur if a second cursor modifies
|
| + ** the page while cursor pCur is holding a reference to it. Which can
|
| + ** only happen if the database is corrupt in such a way as to link the
|
| + ** page into more than one b-tree structure. */
|
| + testcase( idx>pPage->nCell );
|
| +
|
| + if( idx>=pPage->nCell ){
|
| + if( !pPage->leaf ){
|
| + rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
|
| + if( rc ) return rc;
|
| + return moveToLeftmost(pCur);
|
| + }
|
| + do{
|
| + if( pCur->iPage==0 ){
|
| + *pRes = 1;
|
| + pCur->eState = CURSOR_INVALID;
|
| + return SQLITE_OK;
|
| + }
|
| + moveToParent(pCur);
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + }while( pCur->aiIdx[pCur->iPage]>=pPage->nCell );
|
| + if( pPage->intKey ){
|
| + return sqlite3BtreeNext(pCur, pRes);
|
| + }else{
|
| + return SQLITE_OK;
|
| + }
|
| + }
|
| + if( pPage->leaf ){
|
| + return SQLITE_OK;
|
| + }else{
|
| + return moveToLeftmost(pCur);
|
| + }
|
| +}
|
| +int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
|
| + MemPage *pPage;
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pRes!=0 );
|
| + assert( *pRes==0 || *pRes==1 );
|
| + assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
|
| + pCur->info.nSize = 0;
|
| + pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
|
| + *pRes = 0;
|
| + if( pCur->eState!=CURSOR_VALID ) return btreeNext(pCur, pRes);
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + if( (++pCur->aiIdx[pCur->iPage])>=pPage->nCell ){
|
| + pCur->aiIdx[pCur->iPage]--;
|
| + return btreeNext(pCur, pRes);
|
| + }
|
| + if( pPage->leaf ){
|
| + return SQLITE_OK;
|
| + }else{
|
| + return moveToLeftmost(pCur);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Step the cursor to the back to the previous entry in the database. If
|
| +** successful then set *pRes=0. If the cursor
|
| +** was already pointing to the first entry in the database before
|
| +** this routine was called, then set *pRes=1.
|
| +**
|
| +** The main entry point is sqlite3BtreePrevious(). That routine is optimized
|
| +** for the common case of merely decrementing the cell counter BtCursor.aiIdx
|
| +** to the previous cell on the current page. The (slower) btreePrevious()
|
| +** helper routine is called when it is necessary to move to a different page
|
| +** or to restore the cursor.
|
| +**
|
| +** The calling function will set *pRes to 0 or 1. The initial *pRes value
|
| +** will be 1 if the cursor being stepped corresponds to an SQL index and
|
| +** if this routine could have been skipped if that SQL index had been
|
| +** a unique index. Otherwise the caller will have set *pRes to zero.
|
| +** Zero is the common case. The btree implementation is free to use the
|
| +** initial *pRes value as a hint to improve performance, but the current
|
| +** SQLite btree implementation does not. (Note that the comdb2 btree
|
| +** implementation does use this hint, however.)
|
| +*/
|
| +static SQLITE_NOINLINE int btreePrevious(BtCursor *pCur, int *pRes){
|
| + int rc;
|
| + MemPage *pPage;
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pRes!=0 );
|
| + assert( *pRes==0 );
|
| + assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
|
| + assert( (pCur->curFlags & (BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey))==0 );
|
| + assert( pCur->info.nSize==0 );
|
| + if( pCur->eState!=CURSOR_VALID ){
|
| + rc = restoreCursorPosition(pCur);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + if( CURSOR_INVALID==pCur->eState ){
|
| + *pRes = 1;
|
| + return SQLITE_OK;
|
| + }
|
| + if( pCur->skipNext ){
|
| + assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
|
| + pCur->eState = CURSOR_VALID;
|
| + if( pCur->skipNext<0 ){
|
| + pCur->skipNext = 0;
|
| + return SQLITE_OK;
|
| + }
|
| + pCur->skipNext = 0;
|
| + }
|
| + }
|
| +
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + assert( pPage->isInit );
|
| + if( !pPage->leaf ){
|
| + int idx = pCur->aiIdx[pCur->iPage];
|
| + rc = moveToChild(pCur, get4byte(findCell(pPage, idx)));
|
| + if( rc ) return rc;
|
| + rc = moveToRightmost(pCur);
|
| + }else{
|
| + while( pCur->aiIdx[pCur->iPage]==0 ){
|
| + if( pCur->iPage==0 ){
|
| + pCur->eState = CURSOR_INVALID;
|
| + *pRes = 1;
|
| + return SQLITE_OK;
|
| + }
|
| + moveToParent(pCur);
|
| + }
|
| + assert( pCur->info.nSize==0 );
|
| + assert( (pCur->curFlags & (BTCF_ValidOvfl))==0 );
|
| +
|
| + pCur->aiIdx[pCur->iPage]--;
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + if( pPage->intKey && !pPage->leaf ){
|
| + rc = sqlite3BtreePrevious(pCur, pRes);
|
| + }else{
|
| + rc = SQLITE_OK;
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pRes!=0 );
|
| + assert( *pRes==0 || *pRes==1 );
|
| + assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
|
| + *pRes = 0;
|
| + pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey);
|
| + pCur->info.nSize = 0;
|
| + if( pCur->eState!=CURSOR_VALID
|
| + || pCur->aiIdx[pCur->iPage]==0
|
| + || pCur->apPage[pCur->iPage]->leaf==0
|
| + ){
|
| + return btreePrevious(pCur, pRes);
|
| + }
|
| + pCur->aiIdx[pCur->iPage]--;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Allocate a new page from the database file.
|
| +**
|
| +** The new page is marked as dirty. (In other words, sqlite3PagerWrite()
|
| +** has already been called on the new page.) The new page has also
|
| +** been referenced and the calling routine is responsible for calling
|
| +** sqlite3PagerUnref() on the new page when it is done.
|
| +**
|
| +** SQLITE_OK is returned on success. Any other return value indicates
|
| +** an error. *ppPage is set to NULL in the event of an error.
|
| +**
|
| +** If the "nearby" parameter is not 0, then an effort is made to
|
| +** locate a page close to the page number "nearby". This can be used in an
|
| +** attempt to keep related pages close to each other in the database file,
|
| +** which in turn can make database access faster.
|
| +**
|
| +** If the eMode parameter is BTALLOC_EXACT and the nearby page exists
|
| +** anywhere on the free-list, then it is guaranteed to be returned. If
|
| +** eMode is BTALLOC_LT then the page returned will be less than or equal
|
| +** to nearby if any such page exists. If eMode is BTALLOC_ANY then there
|
| +** are no restrictions on which page is returned.
|
| +*/
|
| +static int allocateBtreePage(
|
| + BtShared *pBt, /* The btree */
|
| + MemPage **ppPage, /* Store pointer to the allocated page here */
|
| + Pgno *pPgno, /* Store the page number here */
|
| + Pgno nearby, /* Search for a page near this one */
|
| + u8 eMode /* BTALLOC_EXACT, BTALLOC_LT, or BTALLOC_ANY */
|
| +){
|
| + MemPage *pPage1;
|
| + int rc;
|
| + u32 n; /* Number of pages on the freelist */
|
| + u32 k; /* Number of leaves on the trunk of the freelist */
|
| + MemPage *pTrunk = 0;
|
| + MemPage *pPrevTrunk = 0;
|
| + Pgno mxPage; /* Total size of the database file */
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( eMode==BTALLOC_ANY || (nearby>0 && IfNotOmitAV(pBt->autoVacuum)) );
|
| + pPage1 = pBt->pPage1;
|
| + mxPage = btreePagecount(pBt);
|
| + /* EVIDENCE-OF: R-05119-02637 The 4-byte big-endian integer at offset 36
|
| + ** stores stores the total number of pages on the freelist. */
|
| + n = get4byte(&pPage1->aData[36]);
|
| + testcase( n==mxPage-1 );
|
| + if( n>=mxPage ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + if( n>0 ){
|
| + /* There are pages on the freelist. Reuse one of those pages. */
|
| + Pgno iTrunk;
|
| + u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
|
| + u32 nSearch = 0; /* Count of the number of search attempts */
|
| +
|
| + /* If eMode==BTALLOC_EXACT and a query of the pointer-map
|
| + ** shows that the page 'nearby' is somewhere on the free-list, then
|
| + ** the entire-list will be searched for that page.
|
| + */
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( eMode==BTALLOC_EXACT ){
|
| + if( nearby<=mxPage ){
|
| + u8 eType;
|
| + assert( nearby>0 );
|
| + assert( pBt->autoVacuum );
|
| + rc = ptrmapGet(pBt, nearby, &eType, 0);
|
| + if( rc ) return rc;
|
| + if( eType==PTRMAP_FREEPAGE ){
|
| + searchList = 1;
|
| + }
|
| + }
|
| + }else if( eMode==BTALLOC_LE ){
|
| + searchList = 1;
|
| + }
|
| +#endif
|
| +
|
| + /* Decrement the free-list count by 1. Set iTrunk to the index of the
|
| + ** first free-list trunk page. iPrevTrunk is initially 1.
|
| + */
|
| + rc = sqlite3PagerWrite(pPage1->pDbPage);
|
| + if( rc ) return rc;
|
| + put4byte(&pPage1->aData[36], n-1);
|
| +
|
| + /* The code within this loop is run only once if the 'searchList' variable
|
| + ** is not true. Otherwise, it runs once for each trunk-page on the
|
| + ** free-list until the page 'nearby' is located (eMode==BTALLOC_EXACT)
|
| + ** or until a page less than 'nearby' is located (eMode==BTALLOC_LT)
|
| + */
|
| + do {
|
| + pPrevTrunk = pTrunk;
|
| + if( pPrevTrunk ){
|
| + /* EVIDENCE-OF: R-01506-11053 The first integer on a freelist trunk page
|
| + ** is the page number of the next freelist trunk page in the list or
|
| + ** zero if this is the last freelist trunk page. */
|
| + iTrunk = get4byte(&pPrevTrunk->aData[0]);
|
| + }else{
|
| + /* EVIDENCE-OF: R-59841-13798 The 4-byte big-endian integer at offset 32
|
| + ** stores the page number of the first page of the freelist, or zero if
|
| + ** the freelist is empty. */
|
| + iTrunk = get4byte(&pPage1->aData[32]);
|
| + }
|
| + testcase( iTrunk==mxPage );
|
| + if( iTrunk>mxPage || nSearch++ > n ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + }else{
|
| + rc = btreeGetUnusedPage(pBt, iTrunk, &pTrunk, 0);
|
| + }
|
| + if( rc ){
|
| + pTrunk = 0;
|
| + goto end_allocate_page;
|
| + }
|
| + assert( pTrunk!=0 );
|
| + assert( pTrunk->aData!=0 );
|
| + /* EVIDENCE-OF: R-13523-04394 The second integer on a freelist trunk page
|
| + ** is the number of leaf page pointers to follow. */
|
| + k = get4byte(&pTrunk->aData[4]);
|
| + if( k==0 && !searchList ){
|
| + /* The trunk has no leaves and the list is not being searched.
|
| + ** So extract the trunk page itself and use it as the newly
|
| + ** allocated page */
|
| + assert( pPrevTrunk==0 );
|
| + rc = sqlite3PagerWrite(pTrunk->pDbPage);
|
| + if( rc ){
|
| + goto end_allocate_page;
|
| + }
|
| + *pPgno = iTrunk;
|
| + memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
|
| + *ppPage = pTrunk;
|
| + pTrunk = 0;
|
| + TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
|
| + }else if( k>(u32)(pBt->usableSize/4 - 2) ){
|
| + /* Value of k is out of range. Database corruption */
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto end_allocate_page;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + }else if( searchList
|
| + && (nearby==iTrunk || (iTrunk<nearby && eMode==BTALLOC_LE))
|
| + ){
|
| + /* The list is being searched and this trunk page is the page
|
| + ** to allocate, regardless of whether it has leaves.
|
| + */
|
| + *pPgno = iTrunk;
|
| + *ppPage = pTrunk;
|
| + searchList = 0;
|
| + rc = sqlite3PagerWrite(pTrunk->pDbPage);
|
| + if( rc ){
|
| + goto end_allocate_page;
|
| + }
|
| + if( k==0 ){
|
| + if( !pPrevTrunk ){
|
| + memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
|
| + }else{
|
| + rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + goto end_allocate_page;
|
| + }
|
| + memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
|
| + }
|
| + }else{
|
| + /* The trunk page is required by the caller but it contains
|
| + ** pointers to free-list leaves. The first leaf becomes a trunk
|
| + ** page in this case.
|
| + */
|
| + MemPage *pNewTrunk;
|
| + Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
|
| + if( iNewTrunk>mxPage ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto end_allocate_page;
|
| + }
|
| + testcase( iNewTrunk==mxPage );
|
| + rc = btreeGetUnusedPage(pBt, iNewTrunk, &pNewTrunk, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + goto end_allocate_page;
|
| + }
|
| + rc = sqlite3PagerWrite(pNewTrunk->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(pNewTrunk);
|
| + goto end_allocate_page;
|
| + }
|
| + memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
|
| + put4byte(&pNewTrunk->aData[4], k-1);
|
| + memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
|
| + releasePage(pNewTrunk);
|
| + if( !pPrevTrunk ){
|
| + assert( sqlite3PagerIswriteable(pPage1->pDbPage) );
|
| + put4byte(&pPage1->aData[32], iNewTrunk);
|
| + }else{
|
| + rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
|
| + if( rc ){
|
| + goto end_allocate_page;
|
| + }
|
| + put4byte(&pPrevTrunk->aData[0], iNewTrunk);
|
| + }
|
| + }
|
| + pTrunk = 0;
|
| + TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
|
| +#endif
|
| + }else if( k>0 ){
|
| + /* Extract a leaf from the trunk */
|
| + u32 closest;
|
| + Pgno iPage;
|
| + unsigned char *aData = pTrunk->aData;
|
| + if( nearby>0 ){
|
| + u32 i;
|
| + closest = 0;
|
| + if( eMode==BTALLOC_LE ){
|
| + for(i=0; i<k; i++){
|
| + iPage = get4byte(&aData[8+i*4]);
|
| + if( iPage<=nearby ){
|
| + closest = i;
|
| + break;
|
| + }
|
| + }
|
| + }else{
|
| + int dist;
|
| + dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);
|
| + for(i=1; i<k; i++){
|
| + int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);
|
| + if( d2<dist ){
|
| + closest = i;
|
| + dist = d2;
|
| + }
|
| + }
|
| + }
|
| + }else{
|
| + closest = 0;
|
| + }
|
| +
|
| + iPage = get4byte(&aData[8+closest*4]);
|
| + testcase( iPage==mxPage );
|
| + if( iPage>mxPage ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto end_allocate_page;
|
| + }
|
| + testcase( iPage==mxPage );
|
| + if( !searchList
|
| + || (iPage==nearby || (iPage<nearby && eMode==BTALLOC_LE))
|
| + ){
|
| + int noContent;
|
| + *pPgno = iPage;
|
| + TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
|
| + ": %d more free pages\n",
|
| + *pPgno, closest+1, k, pTrunk->pgno, n-1));
|
| + rc = sqlite3PagerWrite(pTrunk->pDbPage);
|
| + if( rc ) goto end_allocate_page;
|
| + if( closest<k-1 ){
|
| + memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
|
| + }
|
| + put4byte(&aData[4], k-1);
|
| + noContent = !btreeGetHasContent(pBt, *pPgno)? PAGER_GET_NOCONTENT : 0;
|
| + rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, noContent);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3PagerWrite((*ppPage)->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(*ppPage);
|
| + *ppPage = 0;
|
| + }
|
| + }
|
| + searchList = 0;
|
| + }
|
| + }
|
| + releasePage(pPrevTrunk);
|
| + pPrevTrunk = 0;
|
| + }while( searchList );
|
| + }else{
|
| + /* There are no pages on the freelist, so append a new page to the
|
| + ** database image.
|
| + **
|
| + ** Normally, new pages allocated by this block can be requested from the
|
| + ** pager layer with the 'no-content' flag set. This prevents the pager
|
| + ** from trying to read the pages content from disk. However, if the
|
| + ** current transaction has already run one or more incremental-vacuum
|
| + ** steps, then the page we are about to allocate may contain content
|
| + ** that is required in the event of a rollback. In this case, do
|
| + ** not set the no-content flag. This causes the pager to load and journal
|
| + ** the current page content before overwriting it.
|
| + **
|
| + ** Note that the pager will not actually attempt to load or journal
|
| + ** content for any page that really does lie past the end of the database
|
| + ** file on disk. So the effects of disabling the no-content optimization
|
| + ** here are confined to those pages that lie between the end of the
|
| + ** database image and the end of the database file.
|
| + */
|
| + int bNoContent = (0==IfNotOmitAV(pBt->bDoTruncate))? PAGER_GET_NOCONTENT:0;
|
| +
|
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
|
| + if( rc ) return rc;
|
| + pBt->nPage++;
|
| + if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++;
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){
|
| + /* If *pPgno refers to a pointer-map page, allocate two new pages
|
| + ** at the end of the file instead of one. The first allocated page
|
| + ** becomes a new pointer-map page, the second is used by the caller.
|
| + */
|
| + MemPage *pPg = 0;
|
| + TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
|
| + assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
|
| + rc = btreeGetUnusedPage(pBt, pBt->nPage, &pPg, bNoContent);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3PagerWrite(pPg->pDbPage);
|
| + releasePage(pPg);
|
| + }
|
| + if( rc ) return rc;
|
| + pBt->nPage++;
|
| + if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
|
| + }
|
| +#endif
|
| + put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
|
| + *pPgno = pBt->nPage;
|
| +
|
| + assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
|
| + rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, bNoContent);
|
| + if( rc ) return rc;
|
| + rc = sqlite3PagerWrite((*ppPage)->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(*ppPage);
|
| + *ppPage = 0;
|
| + }
|
| + TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
|
| + }
|
| +
|
| + assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
|
| +
|
| +end_allocate_page:
|
| + releasePage(pTrunk);
|
| + releasePage(pPrevTrunk);
|
| + assert( rc!=SQLITE_OK || sqlite3PagerPageRefcount((*ppPage)->pDbPage)<=1 );
|
| + assert( rc!=SQLITE_OK || (*ppPage)->isInit==0 );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is used to add page iPage to the database file free-list.
|
| +** It is assumed that the page is not already a part of the free-list.
|
| +**
|
| +** The value passed as the second argument to this function is optional.
|
| +** If the caller happens to have a pointer to the MemPage object
|
| +** corresponding to page iPage handy, it may pass it as the second value.
|
| +** Otherwise, it may pass NULL.
|
| +**
|
| +** If a pointer to a MemPage object is passed as the second argument,
|
| +** its reference count is not altered by this function.
|
| +*/
|
| +static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
|
| + MemPage *pTrunk = 0; /* Free-list trunk page */
|
| + Pgno iTrunk = 0; /* Page number of free-list trunk page */
|
| + MemPage *pPage1 = pBt->pPage1; /* Local reference to page 1 */
|
| + MemPage *pPage; /* Page being freed. May be NULL. */
|
| + int rc; /* Return Code */
|
| + int nFree; /* Initial number of pages on free-list */
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( CORRUPT_DB || iPage>1 );
|
| + assert( !pMemPage || pMemPage->pgno==iPage );
|
| +
|
| + if( iPage<2 ) return SQLITE_CORRUPT_BKPT;
|
| + if( pMemPage ){
|
| + pPage = pMemPage;
|
| + sqlite3PagerRef(pPage->pDbPage);
|
| + }else{
|
| + pPage = btreePageLookup(pBt, iPage);
|
| + }
|
| +
|
| + /* Increment the free page count on pPage1 */
|
| + rc = sqlite3PagerWrite(pPage1->pDbPage);
|
| + if( rc ) goto freepage_out;
|
| + nFree = get4byte(&pPage1->aData[36]);
|
| + put4byte(&pPage1->aData[36], nFree+1);
|
| +
|
| + if( pBt->btsFlags & BTS_SECURE_DELETE ){
|
| + /* If the secure_delete option is enabled, then
|
| + ** always fully overwrite deleted information with zeros.
|
| + */
|
| + if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0) )
|
| + || ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0)
|
| + ){
|
| + goto freepage_out;
|
| + }
|
| + memset(pPage->aData, 0, pPage->pBt->pageSize);
|
| + }
|
| +
|
| + /* If the database supports auto-vacuum, write an entry in the pointer-map
|
| + ** to indicate that the page is free.
|
| + */
|
| + if( ISAUTOVACUUM ){
|
| + ptrmapPut(pBt, iPage, PTRMAP_FREEPAGE, 0, &rc);
|
| + if( rc ) goto freepage_out;
|
| + }
|
| +
|
| + /* Now manipulate the actual database free-list structure. There are two
|
| + ** possibilities. If the free-list is currently empty, or if the first
|
| + ** trunk page in the free-list is full, then this page will become a
|
| + ** new free-list trunk page. Otherwise, it will become a leaf of the
|
| + ** first trunk page in the current free-list. This block tests if it
|
| + ** is possible to add the page as a new free-list leaf.
|
| + */
|
| + if( nFree!=0 ){
|
| + u32 nLeaf; /* Initial number of leaf cells on trunk page */
|
| +
|
| + iTrunk = get4byte(&pPage1->aData[32]);
|
| + rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + goto freepage_out;
|
| + }
|
| +
|
| + nLeaf = get4byte(&pTrunk->aData[4]);
|
| + assert( pBt->usableSize>32 );
|
| + if( nLeaf > (u32)pBt->usableSize/4 - 2 ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto freepage_out;
|
| + }
|
| + if( nLeaf < (u32)pBt->usableSize/4 - 8 ){
|
| + /* In this case there is room on the trunk page to insert the page
|
| + ** being freed as a new leaf.
|
| + **
|
| + ** Note that the trunk page is not really full until it contains
|
| + ** usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have
|
| + ** coded. But due to a coding error in versions of SQLite prior to
|
| + ** 3.6.0, databases with freelist trunk pages holding more than
|
| + ** usableSize/4 - 8 entries will be reported as corrupt. In order
|
| + ** to maintain backwards compatibility with older versions of SQLite,
|
| + ** we will continue to restrict the number of entries to usableSize/4 - 8
|
| + ** for now. At some point in the future (once everyone has upgraded
|
| + ** to 3.6.0 or later) we should consider fixing the conditional above
|
| + ** to read "usableSize/4-2" instead of "usableSize/4-8".
|
| + **
|
| + ** EVIDENCE-OF: R-19920-11576 However, newer versions of SQLite still
|
| + ** avoid using the last six entries in the freelist trunk page array in
|
| + ** order that database files created by newer versions of SQLite can be
|
| + ** read by older versions of SQLite.
|
| + */
|
| + rc = sqlite3PagerWrite(pTrunk->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + put4byte(&pTrunk->aData[4], nLeaf+1);
|
| + put4byte(&pTrunk->aData[8+nLeaf*4], iPage);
|
| + if( pPage && (pBt->btsFlags & BTS_SECURE_DELETE)==0 ){
|
| + sqlite3PagerDontWrite(pPage->pDbPage);
|
| + }
|
| + rc = btreeSetHasContent(pBt, iPage);
|
| + }
|
| + TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
|
| + goto freepage_out;
|
| + }
|
| + }
|
| +
|
| + /* If control flows to this point, then it was not possible to add the
|
| + ** the page being freed as a leaf page of the first trunk in the free-list.
|
| + ** Possibly because the free-list is empty, or possibly because the
|
| + ** first trunk in the free-list is full. Either way, the page being freed
|
| + ** will become the new first trunk page in the free-list.
|
| + */
|
| + if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0)) ){
|
| + goto freepage_out;
|
| + }
|
| + rc = sqlite3PagerWrite(pPage->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + goto freepage_out;
|
| + }
|
| + put4byte(pPage->aData, iTrunk);
|
| + put4byte(&pPage->aData[4], 0);
|
| + put4byte(&pPage1->aData[32], iPage);
|
| + TRACE(("FREE-PAGE: %d new trunk page replacing %d\n", pPage->pgno, iTrunk));
|
| +
|
| +freepage_out:
|
| + if( pPage ){
|
| + pPage->isInit = 0;
|
| + }
|
| + releasePage(pPage);
|
| + releasePage(pTrunk);
|
| + return rc;
|
| +}
|
| +static void freePage(MemPage *pPage, int *pRC){
|
| + if( (*pRC)==SQLITE_OK ){
|
| + *pRC = freePage2(pPage->pBt, pPage, pPage->pgno);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Free any overflow pages associated with the given Cell. Write the
|
| +** local Cell size (the number of bytes on the original page, omitting
|
| +** overflow) into *pnSize.
|
| +*/
|
| +static int clearCell(
|
| + MemPage *pPage, /* The page that contains the Cell */
|
| + unsigned char *pCell, /* First byte of the Cell */
|
| + CellInfo *pInfo /* Size information about the cell */
|
| +){
|
| + BtShared *pBt = pPage->pBt;
|
| + Pgno ovflPgno;
|
| + int rc;
|
| + int nOvfl;
|
| + u32 ovflPageSize;
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + pPage->xParseCell(pPage, pCell, pInfo);
|
| + if( pInfo->nLocal==pInfo->nPayload ){
|
| + return SQLITE_OK; /* No overflow pages. Return without doing anything */
|
| + }
|
| + if( pCell+pInfo->nSize-1 > pPage->aData+pPage->maskPage ){
|
| + return SQLITE_CORRUPT_BKPT; /* Cell extends past end of page */
|
| + }
|
| + ovflPgno = get4byte(pCell + pInfo->nSize - 4);
|
| + assert( pBt->usableSize > 4 );
|
| + ovflPageSize = pBt->usableSize - 4;
|
| + nOvfl = (pInfo->nPayload - pInfo->nLocal + ovflPageSize - 1)/ovflPageSize;
|
| + assert( nOvfl>0 ||
|
| + (CORRUPT_DB && (pInfo->nPayload + ovflPageSize)<ovflPageSize)
|
| + );
|
| + while( nOvfl-- ){
|
| + Pgno iNext = 0;
|
| + MemPage *pOvfl = 0;
|
| + if( ovflPgno<2 || ovflPgno>btreePagecount(pBt) ){
|
| + /* 0 is not a legal page number and page 1 cannot be an
|
| + ** overflow page. Therefore if ovflPgno<2 or past the end of the
|
| + ** file the database must be corrupt. */
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + if( nOvfl ){
|
| + rc = getOverflowPage(pBt, ovflPgno, &pOvfl, &iNext);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + if( ( pOvfl || ((pOvfl = btreePageLookup(pBt, ovflPgno))!=0) )
|
| + && sqlite3PagerPageRefcount(pOvfl->pDbPage)!=1
|
| + ){
|
| + /* There is no reason any cursor should have an outstanding reference
|
| + ** to an overflow page belonging to a cell that is being deleted/updated.
|
| + ** So if there exists more than one reference to this page, then it
|
| + ** must not really be an overflow page and the database must be corrupt.
|
| + ** It is helpful to detect this before calling freePage2(), as
|
| + ** freePage2() may zero the page contents if secure-delete mode is
|
| + ** enabled. If this 'overflow' page happens to be a page that the
|
| + ** caller is iterating through or using in some other way, this
|
| + ** can be problematic.
|
| + */
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + }else{
|
| + rc = freePage2(pBt, pOvfl, ovflPgno);
|
| + }
|
| +
|
| + if( pOvfl ){
|
| + sqlite3PagerUnref(pOvfl->pDbPage);
|
| + }
|
| + if( rc ) return rc;
|
| + ovflPgno = iNext;
|
| + }
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Create the byte sequence used to represent a cell on page pPage
|
| +** and write that byte sequence into pCell[]. Overflow pages are
|
| +** allocated and filled in as necessary. The calling procedure
|
| +** is responsible for making sure sufficient space has been allocated
|
| +** for pCell[].
|
| +**
|
| +** Note that pCell does not necessary need to point to the pPage->aData
|
| +** area. pCell might point to some temporary storage. The cell will
|
| +** be constructed in this temporary area then copied into pPage->aData
|
| +** later.
|
| +*/
|
| +static int fillInCell(
|
| + MemPage *pPage, /* The page that contains the cell */
|
| + unsigned char *pCell, /* Complete text of the cell */
|
| + const BtreePayload *pX, /* Payload with which to construct the cell */
|
| + int *pnSize /* Write cell size here */
|
| +){
|
| + int nPayload;
|
| + const u8 *pSrc;
|
| + int nSrc, n, rc;
|
| + int spaceLeft;
|
| + MemPage *pOvfl = 0;
|
| + MemPage *pToRelease = 0;
|
| + unsigned char *pPrior;
|
| + unsigned char *pPayload;
|
| + BtShared *pBt = pPage->pBt;
|
| + Pgno pgnoOvfl = 0;
|
| + int nHeader;
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| +
|
| + /* pPage is not necessarily writeable since pCell might be auxiliary
|
| + ** buffer space that is separate from the pPage buffer area */
|
| + assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
|
| + || sqlite3PagerIswriteable(pPage->pDbPage) );
|
| +
|
| + /* Fill in the header. */
|
| + nHeader = pPage->childPtrSize;
|
| + if( pPage->intKey ){
|
| + nPayload = pX->nData + pX->nZero;
|
| + pSrc = pX->pData;
|
| + nSrc = pX->nData;
|
| + assert( pPage->intKeyLeaf ); /* fillInCell() only called for leaves */
|
| + nHeader += putVarint32(&pCell[nHeader], nPayload);
|
| + nHeader += putVarint(&pCell[nHeader], *(u64*)&pX->nKey);
|
| + }else{
|
| + assert( pX->nKey<=0x7fffffff && pX->pKey!=0 );
|
| + nSrc = nPayload = (int)pX->nKey;
|
| + pSrc = pX->pKey;
|
| + nHeader += putVarint32(&pCell[nHeader], nPayload);
|
| + }
|
| +
|
| + /* Fill in the payload */
|
| + if( nPayload<=pPage->maxLocal ){
|
| + n = nHeader + nPayload;
|
| + testcase( n==3 );
|
| + testcase( n==4 );
|
| + if( n<4 ) n = 4;
|
| + *pnSize = n;
|
| + spaceLeft = nPayload;
|
| + pPrior = pCell;
|
| + }else{
|
| + int mn = pPage->minLocal;
|
| + n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
|
| + testcase( n==pPage->maxLocal );
|
| + testcase( n==pPage->maxLocal+1 );
|
| + if( n > pPage->maxLocal ) n = mn;
|
| + spaceLeft = n;
|
| + *pnSize = n + nHeader + 4;
|
| + pPrior = &pCell[nHeader+n];
|
| + }
|
| + pPayload = &pCell[nHeader];
|
| +
|
| + /* At this point variables should be set as follows:
|
| + **
|
| + ** nPayload Total payload size in bytes
|
| + ** pPayload Begin writing payload here
|
| + ** spaceLeft Space available at pPayload. If nPayload>spaceLeft,
|
| + ** that means content must spill into overflow pages.
|
| + ** *pnSize Size of the local cell (not counting overflow pages)
|
| + ** pPrior Where to write the pgno of the first overflow page
|
| + **
|
| + ** Use a call to btreeParseCellPtr() to verify that the values above
|
| + ** were computed correctly.
|
| + */
|
| +#if SQLITE_DEBUG
|
| + {
|
| + CellInfo info;
|
| + pPage->xParseCell(pPage, pCell, &info);
|
| + assert( nHeader==(int)(info.pPayload - pCell) );
|
| + assert( info.nKey==pX->nKey );
|
| + assert( *pnSize == info.nSize );
|
| + assert( spaceLeft == info.nLocal );
|
| + }
|
| +#endif
|
| +
|
| + /* Write the payload into the local Cell and any extra into overflow pages */
|
| + while( nPayload>0 ){
|
| + if( spaceLeft==0 ){
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
|
| + if( pBt->autoVacuum ){
|
| + do{
|
| + pgnoOvfl++;
|
| + } while(
|
| + PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt)
|
| + );
|
| + }
|
| +#endif
|
| + rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + /* If the database supports auto-vacuum, and the second or subsequent
|
| + ** overflow page is being allocated, add an entry to the pointer-map
|
| + ** for that page now.
|
| + **
|
| + ** If this is the first overflow page, then write a partial entry
|
| + ** to the pointer-map. If we write nothing to this pointer-map slot,
|
| + ** then the optimistic overflow chain processing in clearCell()
|
| + ** may misinterpret the uninitialized values and delete the
|
| + ** wrong pages from the database.
|
| + */
|
| + if( pBt->autoVacuum && rc==SQLITE_OK ){
|
| + u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
|
| + ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc);
|
| + if( rc ){
|
| + releasePage(pOvfl);
|
| + }
|
| + }
|
| +#endif
|
| + if( rc ){
|
| + releasePage(pToRelease);
|
| + return rc;
|
| + }
|
| +
|
| + /* If pToRelease is not zero than pPrior points into the data area
|
| + ** of pToRelease. Make sure pToRelease is still writeable. */
|
| + assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
|
| +
|
| + /* If pPrior is part of the data area of pPage, then make sure pPage
|
| + ** is still writeable */
|
| + assert( pPrior<pPage->aData || pPrior>=&pPage->aData[pBt->pageSize]
|
| + || sqlite3PagerIswriteable(pPage->pDbPage) );
|
| +
|
| + put4byte(pPrior, pgnoOvfl);
|
| + releasePage(pToRelease);
|
| + pToRelease = pOvfl;
|
| + pPrior = pOvfl->aData;
|
| + put4byte(pPrior, 0);
|
| + pPayload = &pOvfl->aData[4];
|
| + spaceLeft = pBt->usableSize - 4;
|
| + }
|
| + n = nPayload;
|
| + if( n>spaceLeft ) n = spaceLeft;
|
| +
|
| + /* If pToRelease is not zero than pPayload points into the data area
|
| + ** of pToRelease. Make sure pToRelease is still writeable. */
|
| + assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
|
| +
|
| + /* If pPayload is part of the data area of pPage, then make sure pPage
|
| + ** is still writeable */
|
| + assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
|
| + || sqlite3PagerIswriteable(pPage->pDbPage) );
|
| +
|
| + if( nSrc>0 ){
|
| + if( n>nSrc ) n = nSrc;
|
| + assert( pSrc );
|
| + memcpy(pPayload, pSrc, n);
|
| + }else{
|
| + memset(pPayload, 0, n);
|
| + }
|
| + nPayload -= n;
|
| + pPayload += n;
|
| + pSrc += n;
|
| + nSrc -= n;
|
| + spaceLeft -= n;
|
| + }
|
| + releasePage(pToRelease);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Remove the i-th cell from pPage. This routine effects pPage only.
|
| +** The cell content is not freed or deallocated. It is assumed that
|
| +** the cell content has been copied someplace else. This routine just
|
| +** removes the reference to the cell from pPage.
|
| +**
|
| +** "sz" must be the number of bytes in the cell.
|
| +*/
|
| +static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
|
| + u32 pc; /* Offset to cell content of cell being deleted */
|
| + u8 *data; /* pPage->aData */
|
| + u8 *ptr; /* Used to move bytes around within data[] */
|
| + int rc; /* The return code */
|
| + int hdr; /* Beginning of the header. 0 most pages. 100 page 1 */
|
| +
|
| + if( *pRC ) return;
|
| + assert( idx>=0 && idx<pPage->nCell );
|
| + assert( CORRUPT_DB || sz==cellSize(pPage, idx) );
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + data = pPage->aData;
|
| + ptr = &pPage->aCellIdx[2*idx];
|
| + pc = get2byte(ptr);
|
| + hdr = pPage->hdrOffset;
|
| + testcase( pc==get2byte(&data[hdr+5]) );
|
| + testcase( pc+sz==pPage->pBt->usableSize );
|
| + if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
|
| + *pRC = SQLITE_CORRUPT_BKPT;
|
| + return;
|
| + }
|
| + rc = freeSpace(pPage, pc, sz);
|
| + if( rc ){
|
| + *pRC = rc;
|
| + return;
|
| + }
|
| + pPage->nCell--;
|
| + if( pPage->nCell==0 ){
|
| + memset(&data[hdr+1], 0, 4);
|
| + data[hdr+7] = 0;
|
| + put2byte(&data[hdr+5], pPage->pBt->usableSize);
|
| + pPage->nFree = pPage->pBt->usableSize - pPage->hdrOffset
|
| + - pPage->childPtrSize - 8;
|
| + }else{
|
| + memmove(ptr, ptr+2, 2*(pPage->nCell - idx));
|
| + put2byte(&data[hdr+3], pPage->nCell);
|
| + pPage->nFree += 2;
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Insert a new cell on pPage at cell index "i". pCell points to the
|
| +** content of the cell.
|
| +**
|
| +** If the cell content will fit on the page, then put it there. If it
|
| +** will not fit, then make a copy of the cell content into pTemp if
|
| +** pTemp is not null. Regardless of pTemp, allocate a new entry
|
| +** in pPage->apOvfl[] and make it point to the cell content (either
|
| +** in pTemp or the original pCell) and also record its index.
|
| +** Allocating a new entry in pPage->aCell[] implies that
|
| +** pPage->nOverflow is incremented.
|
| +**
|
| +** *pRC must be SQLITE_OK when this routine is called.
|
| +*/
|
| +static void insertCell(
|
| + MemPage *pPage, /* Page into which we are copying */
|
| + int i, /* New cell becomes the i-th cell of the page */
|
| + u8 *pCell, /* Content of the new cell */
|
| + int sz, /* Bytes of content in pCell */
|
| + u8 *pTemp, /* Temp storage space for pCell, if needed */
|
| + Pgno iChild, /* If non-zero, replace first 4 bytes with this value */
|
| + int *pRC /* Read and write return code from here */
|
| +){
|
| + int idx = 0; /* Where to write new cell content in data[] */
|
| + int j; /* Loop counter */
|
| + u8 *data; /* The content of the whole page */
|
| + u8 *pIns; /* The point in pPage->aCellIdx[] where no cell inserted */
|
| +
|
| + assert( *pRC==SQLITE_OK );
|
| + assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
|
| + assert( MX_CELL(pPage->pBt)<=10921 );
|
| + assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB );
|
| + assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) );
|
| + assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) );
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + /* The cell should normally be sized correctly. However, when moving a
|
| + ** malformed cell from a leaf page to an interior page, if the cell size
|
| + ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
|
| + ** might be less than 8 (leaf-size + pointer) on the interior node. Hence
|
| + ** the term after the || in the following assert(). */
|
| + assert( sz==pPage->xCellSize(pPage, pCell) || (sz==8 && iChild>0) );
|
| + if( pPage->nOverflow || sz+2>pPage->nFree ){
|
| + if( pTemp ){
|
| + memcpy(pTemp, pCell, sz);
|
| + pCell = pTemp;
|
| + }
|
| + if( iChild ){
|
| + put4byte(pCell, iChild);
|
| + }
|
| + j = pPage->nOverflow++;
|
| + /* Comparison against ArraySize-1 since we hold back one extra slot
|
| + ** as a contingency. In other words, never need more than 3 overflow
|
| + ** slots but 4 are allocated, just to be safe. */
|
| + assert( j < ArraySize(pPage->apOvfl)-1 );
|
| + pPage->apOvfl[j] = pCell;
|
| + pPage->aiOvfl[j] = (u16)i;
|
| +
|
| + /* When multiple overflows occur, they are always sequential and in
|
| + ** sorted order. This invariants arise because multiple overflows can
|
| + ** only occur when inserting divider cells into the parent page during
|
| + ** balancing, and the dividers are adjacent and sorted.
|
| + */
|
| + assert( j==0 || pPage->aiOvfl[j-1]<(u16)i ); /* Overflows in sorted order */
|
| + assert( j==0 || i==pPage->aiOvfl[j-1]+1 ); /* Overflows are sequential */
|
| + }else{
|
| + int rc = sqlite3PagerWrite(pPage->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + *pRC = rc;
|
| + return;
|
| + }
|
| + assert( sqlite3PagerIswriteable(pPage->pDbPage) );
|
| + data = pPage->aData;
|
| + assert( &data[pPage->cellOffset]==pPage->aCellIdx );
|
| + rc = allocateSpace(pPage, sz, &idx);
|
| + if( rc ){ *pRC = rc; return; }
|
| + /* The allocateSpace() routine guarantees the following properties
|
| + ** if it returns successfully */
|
| + assert( idx >= 0 );
|
| + assert( idx >= pPage->cellOffset+2*pPage->nCell+2 || CORRUPT_DB );
|
| + assert( idx+sz <= (int)pPage->pBt->usableSize );
|
| + pPage->nFree -= (u16)(2 + sz);
|
| + memcpy(&data[idx], pCell, sz);
|
| + if( iChild ){
|
| + put4byte(&data[idx], iChild);
|
| + }
|
| + pIns = pPage->aCellIdx + i*2;
|
| + memmove(pIns+2, pIns, 2*(pPage->nCell - i));
|
| + put2byte(pIns, idx);
|
| + pPage->nCell++;
|
| + /* increment the cell count */
|
| + if( (++data[pPage->hdrOffset+4])==0 ) data[pPage->hdrOffset+3]++;
|
| + assert( get2byte(&data[pPage->hdrOffset+3])==pPage->nCell );
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pPage->pBt->autoVacuum ){
|
| + /* The cell may contain a pointer to an overflow page. If so, write
|
| + ** the entry for the overflow page into the pointer map.
|
| + */
|
| + ptrmapPutOvflPtr(pPage, pCell, pRC);
|
| + }
|
| +#endif
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** A CellArray object contains a cache of pointers and sizes for a
|
| +** consecutive sequence of cells that might be held on multiple pages.
|
| +*/
|
| +typedef struct CellArray CellArray;
|
| +struct CellArray {
|
| + int nCell; /* Number of cells in apCell[] */
|
| + MemPage *pRef; /* Reference page */
|
| + u8 **apCell; /* All cells begin balanced */
|
| + u16 *szCell; /* Local size of all cells in apCell[] */
|
| +};
|
| +
|
| +/*
|
| +** Make sure the cell sizes at idx, idx+1, ..., idx+N-1 have been
|
| +** computed.
|
| +*/
|
| +static void populateCellCache(CellArray *p, int idx, int N){
|
| + assert( idx>=0 && idx+N<=p->nCell );
|
| + while( N>0 ){
|
| + assert( p->apCell[idx]!=0 );
|
| + if( p->szCell[idx]==0 ){
|
| + p->szCell[idx] = p->pRef->xCellSize(p->pRef, p->apCell[idx]);
|
| + }else{
|
| + assert( CORRUPT_DB ||
|
| + p->szCell[idx]==p->pRef->xCellSize(p->pRef, p->apCell[idx]) );
|
| + }
|
| + idx++;
|
| + N--;
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Return the size of the Nth element of the cell array
|
| +*/
|
| +static SQLITE_NOINLINE u16 computeCellSize(CellArray *p, int N){
|
| + assert( N>=0 && N<p->nCell );
|
| + assert( p->szCell[N]==0 );
|
| + p->szCell[N] = p->pRef->xCellSize(p->pRef, p->apCell[N]);
|
| + return p->szCell[N];
|
| +}
|
| +static u16 cachedCellSize(CellArray *p, int N){
|
| + assert( N>=0 && N<p->nCell );
|
| + if( p->szCell[N] ) return p->szCell[N];
|
| + return computeCellSize(p, N);
|
| +}
|
| +
|
| +/*
|
| +** Array apCell[] contains pointers to nCell b-tree page cells. The
|
| +** szCell[] array contains the size in bytes of each cell. This function
|
| +** replaces the current contents of page pPg with the contents of the cell
|
| +** array.
|
| +**
|
| +** Some of the cells in apCell[] may currently be stored in pPg. This
|
| +** function works around problems caused by this by making a copy of any
|
| +** such cells before overwriting the page data.
|
| +**
|
| +** The MemPage.nFree field is invalidated by this function. It is the
|
| +** responsibility of the caller to set it correctly.
|
| +*/
|
| +static int rebuildPage(
|
| + MemPage *pPg, /* Edit this page */
|
| + int nCell, /* Final number of cells on page */
|
| + u8 **apCell, /* Array of cells */
|
| + u16 *szCell /* Array of cell sizes */
|
| +){
|
| + const int hdr = pPg->hdrOffset; /* Offset of header on pPg */
|
| + u8 * const aData = pPg->aData; /* Pointer to data for pPg */
|
| + const int usableSize = pPg->pBt->usableSize;
|
| + u8 * const pEnd = &aData[usableSize];
|
| + int i;
|
| + u8 *pCellptr = pPg->aCellIdx;
|
| + u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
|
| + u8 *pData;
|
| +
|
| + i = get2byte(&aData[hdr+5]);
|
| + memcpy(&pTmp[i], &aData[i], usableSize - i);
|
| +
|
| + pData = pEnd;
|
| + for(i=0; i<nCell; i++){
|
| + u8 *pCell = apCell[i];
|
| + if( SQLITE_WITHIN(pCell,aData,pEnd) ){
|
| + pCell = &pTmp[pCell - aData];
|
| + }
|
| + pData -= szCell[i];
|
| + put2byte(pCellptr, (pData - aData));
|
| + pCellptr += 2;
|
| + if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
|
| + memcpy(pData, pCell, szCell[i]);
|
| + assert( szCell[i]==pPg->xCellSize(pPg, pCell) || CORRUPT_DB );
|
| + testcase( szCell[i]!=pPg->xCellSize(pPg,pCell) );
|
| + }
|
| +
|
| + /* The pPg->nFree field is now set incorrectly. The caller will fix it. */
|
| + pPg->nCell = nCell;
|
| + pPg->nOverflow = 0;
|
| +
|
| + put2byte(&aData[hdr+1], 0);
|
| + put2byte(&aData[hdr+3], pPg->nCell);
|
| + put2byte(&aData[hdr+5], pData - aData);
|
| + aData[hdr+7] = 0x00;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
|
| +** contains the size in bytes of each such cell. This function attempts to
|
| +** add the cells stored in the array to page pPg. If it cannot (because
|
| +** the page needs to be defragmented before the cells will fit), non-zero
|
| +** is returned. Otherwise, if the cells are added successfully, zero is
|
| +** returned.
|
| +**
|
| +** Argument pCellptr points to the first entry in the cell-pointer array
|
| +** (part of page pPg) to populate. After cell apCell[0] is written to the
|
| +** page body, a 16-bit offset is written to pCellptr. And so on, for each
|
| +** cell in the array. It is the responsibility of the caller to ensure
|
| +** that it is safe to overwrite this part of the cell-pointer array.
|
| +**
|
| +** When this function is called, *ppData points to the start of the
|
| +** content area on page pPg. If the size of the content area is extended,
|
| +** *ppData is updated to point to the new start of the content area
|
| +** before returning.
|
| +**
|
| +** Finally, argument pBegin points to the byte immediately following the
|
| +** end of the space required by this page for the cell-pointer area (for
|
| +** all cells - not just those inserted by the current call). If the content
|
| +** area must be extended to before this point in order to accomodate all
|
| +** cells in apCell[], then the cells do not fit and non-zero is returned.
|
| +*/
|
| +static int pageInsertArray(
|
| + MemPage *pPg, /* Page to add cells to */
|
| + u8 *pBegin, /* End of cell-pointer array */
|
| + u8 **ppData, /* IN/OUT: Page content -area pointer */
|
| + u8 *pCellptr, /* Pointer to cell-pointer area */
|
| + int iFirst, /* Index of first cell to add */
|
| + int nCell, /* Number of cells to add to pPg */
|
| + CellArray *pCArray /* Array of cells */
|
| +){
|
| + int i;
|
| + u8 *aData = pPg->aData;
|
| + u8 *pData = *ppData;
|
| + int iEnd = iFirst + nCell;
|
| + assert( CORRUPT_DB || pPg->hdrOffset==0 ); /* Never called on page 1 */
|
| + for(i=iFirst; i<iEnd; i++){
|
| + int sz, rc;
|
| + u8 *pSlot;
|
| + sz = cachedCellSize(pCArray, i);
|
| + if( (aData[1]==0 && aData[2]==0) || (pSlot = pageFindSlot(pPg,sz,&rc))==0 ){
|
| + if( (pData - pBegin)<sz ) return 1;
|
| + pData -= sz;
|
| + pSlot = pData;
|
| + }
|
| + /* pSlot and pCArray->apCell[i] will never overlap on a well-formed
|
| + ** database. But they might for a corrupt database. Hence use memmove()
|
| + ** since memcpy() sends SIGABORT with overlapping buffers on OpenBSD */
|
| + assert( (pSlot+sz)<=pCArray->apCell[i]
|
| + || pSlot>=(pCArray->apCell[i]+sz)
|
| + || CORRUPT_DB );
|
| + memmove(pSlot, pCArray->apCell[i], sz);
|
| + put2byte(pCellptr, (pSlot - aData));
|
| + pCellptr += 2;
|
| + }
|
| + *ppData = pData;
|
| + return 0;
|
| +}
|
| +
|
| +/*
|
| +** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
|
| +** contains the size in bytes of each such cell. This function adds the
|
| +** space associated with each cell in the array that is currently stored
|
| +** within the body of pPg to the pPg free-list. The cell-pointers and other
|
| +** fields of the page are not updated.
|
| +**
|
| +** This function returns the total number of cells added to the free-list.
|
| +*/
|
| +static int pageFreeArray(
|
| + MemPage *pPg, /* Page to edit */
|
| + int iFirst, /* First cell to delete */
|
| + int nCell, /* Cells to delete */
|
| + CellArray *pCArray /* Array of cells */
|
| +){
|
| + u8 * const aData = pPg->aData;
|
| + u8 * const pEnd = &aData[pPg->pBt->usableSize];
|
| + u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize];
|
| + int nRet = 0;
|
| + int i;
|
| + int iEnd = iFirst + nCell;
|
| + u8 *pFree = 0;
|
| + int szFree = 0;
|
| +
|
| + for(i=iFirst; i<iEnd; i++){
|
| + u8 *pCell = pCArray->apCell[i];
|
| + if( SQLITE_WITHIN(pCell, pStart, pEnd) ){
|
| + int sz;
|
| + /* No need to use cachedCellSize() here. The sizes of all cells that
|
| + ** are to be freed have already been computing while deciding which
|
| + ** cells need freeing */
|
| + sz = pCArray->szCell[i]; assert( sz>0 );
|
| + if( pFree!=(pCell + sz) ){
|
| + if( pFree ){
|
| + assert( pFree>aData && (pFree - aData)<65536 );
|
| + freeSpace(pPg, (u16)(pFree - aData), szFree);
|
| + }
|
| + pFree = pCell;
|
| + szFree = sz;
|
| + if( pFree+sz>pEnd ) return 0;
|
| + }else{
|
| + pFree = pCell;
|
| + szFree += sz;
|
| + }
|
| + nRet++;
|
| + }
|
| + }
|
| + if( pFree ){
|
| + assert( pFree>aData && (pFree - aData)<65536 );
|
| + freeSpace(pPg, (u16)(pFree - aData), szFree);
|
| + }
|
| + return nRet;
|
| +}
|
| +
|
| +/*
|
| +** apCell[] and szCell[] contains pointers to and sizes of all cells in the
|
| +** pages being balanced. The current page, pPg, has pPg->nCell cells starting
|
| +** with apCell[iOld]. After balancing, this page should hold nNew cells
|
| +** starting at apCell[iNew].
|
| +**
|
| +** This routine makes the necessary adjustments to pPg so that it contains
|
| +** the correct cells after being balanced.
|
| +**
|
| +** The pPg->nFree field is invalid when this function returns. It is the
|
| +** responsibility of the caller to set it correctly.
|
| +*/
|
| +static int editPage(
|
| + MemPage *pPg, /* Edit this page */
|
| + int iOld, /* Index of first cell currently on page */
|
| + int iNew, /* Index of new first cell on page */
|
| + int nNew, /* Final number of cells on page */
|
| + CellArray *pCArray /* Array of cells and sizes */
|
| +){
|
| + u8 * const aData = pPg->aData;
|
| + const int hdr = pPg->hdrOffset;
|
| + u8 *pBegin = &pPg->aCellIdx[nNew * 2];
|
| + int nCell = pPg->nCell; /* Cells stored on pPg */
|
| + u8 *pData;
|
| + u8 *pCellptr;
|
| + int i;
|
| + int iOldEnd = iOld + pPg->nCell + pPg->nOverflow;
|
| + int iNewEnd = iNew + nNew;
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| + u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
|
| + memcpy(pTmp, aData, pPg->pBt->usableSize);
|
| +#endif
|
| +
|
| + /* Remove cells from the start and end of the page */
|
| + if( iOld<iNew ){
|
| + int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray);
|
| + memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
|
| + nCell -= nShift;
|
| + }
|
| + if( iNewEnd < iOldEnd ){
|
| + nCell -= pageFreeArray(pPg, iNewEnd, iOldEnd - iNewEnd, pCArray);
|
| + }
|
| +
|
| + pData = &aData[get2byteNotZero(&aData[hdr+5])];
|
| + if( pData<pBegin ) goto editpage_fail;
|
| +
|
| + /* Add cells to the start of the page */
|
| + if( iNew<iOld ){
|
| + int nAdd = MIN(nNew,iOld-iNew);
|
| + assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB );
|
| + pCellptr = pPg->aCellIdx;
|
| + memmove(&pCellptr[nAdd*2], pCellptr, nCell*2);
|
| + if( pageInsertArray(
|
| + pPg, pBegin, &pData, pCellptr,
|
| + iNew, nAdd, pCArray
|
| + ) ) goto editpage_fail;
|
| + nCell += nAdd;
|
| + }
|
| +
|
| + /* Add any overflow cells */
|
| + for(i=0; i<pPg->nOverflow; i++){
|
| + int iCell = (iOld + pPg->aiOvfl[i]) - iNew;
|
| + if( iCell>=0 && iCell<nNew ){
|
| + pCellptr = &pPg->aCellIdx[iCell * 2];
|
| + memmove(&pCellptr[2], pCellptr, (nCell - iCell) * 2);
|
| + nCell++;
|
| + if( pageInsertArray(
|
| + pPg, pBegin, &pData, pCellptr,
|
| + iCell+iNew, 1, pCArray
|
| + ) ) goto editpage_fail;
|
| + }
|
| + }
|
| +
|
| + /* Append cells to the end of the page */
|
| + pCellptr = &pPg->aCellIdx[nCell*2];
|
| + if( pageInsertArray(
|
| + pPg, pBegin, &pData, pCellptr,
|
| + iNew+nCell, nNew-nCell, pCArray
|
| + ) ) goto editpage_fail;
|
| +
|
| + pPg->nCell = nNew;
|
| + pPg->nOverflow = 0;
|
| +
|
| + put2byte(&aData[hdr+3], pPg->nCell);
|
| + put2byte(&aData[hdr+5], pData - aData);
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| + for(i=0; i<nNew && !CORRUPT_DB; i++){
|
| + u8 *pCell = pCArray->apCell[i+iNew];
|
| + int iOff = get2byteAligned(&pPg->aCellIdx[i*2]);
|
| + if( SQLITE_WITHIN(pCell, aData, &aData[pPg->pBt->usableSize]) ){
|
| + pCell = &pTmp[pCell - aData];
|
| + }
|
| + assert( 0==memcmp(pCell, &aData[iOff],
|
| + pCArray->pRef->xCellSize(pCArray->pRef, pCArray->apCell[i+iNew])) );
|
| + }
|
| +#endif
|
| +
|
| + return SQLITE_OK;
|
| + editpage_fail:
|
| + /* Unable to edit this page. Rebuild it from scratch instead. */
|
| + populateCellCache(pCArray, iNew, nNew);
|
| + return rebuildPage(pPg, nNew, &pCArray->apCell[iNew], &pCArray->szCell[iNew]);
|
| +}
|
| +
|
| +/*
|
| +** The following parameters determine how many adjacent pages get involved
|
| +** in a balancing operation. NN is the number of neighbors on either side
|
| +** of the page that participate in the balancing operation. NB is the
|
| +** total number of pages that participate, including the target page and
|
| +** NN neighbors on either side.
|
| +**
|
| +** The minimum value of NN is 1 (of course). Increasing NN above 1
|
| +** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
|
| +** in exchange for a larger degradation in INSERT and UPDATE performance.
|
| +** The value of NN appears to give the best results overall.
|
| +*/
|
| +#define NN 1 /* Number of neighbors on either side of pPage */
|
| +#define NB (NN*2+1) /* Total pages involved in the balance */
|
| +
|
| +
|
| +#ifndef SQLITE_OMIT_QUICKBALANCE
|
| +/*
|
| +** This version of balance() handles the common special case where
|
| +** a new entry is being inserted on the extreme right-end of the
|
| +** tree, in other words, when the new entry will become the largest
|
| +** entry in the tree.
|
| +**
|
| +** Instead of trying to balance the 3 right-most leaf pages, just add
|
| +** a new page to the right-hand side and put the one new entry in
|
| +** that page. This leaves the right side of the tree somewhat
|
| +** unbalanced. But odds are that we will be inserting new entries
|
| +** at the end soon afterwards so the nearly empty page will quickly
|
| +** fill up. On average.
|
| +**
|
| +** pPage is the leaf page which is the right-most page in the tree.
|
| +** pParent is its parent. pPage must have a single overflow entry
|
| +** which is also the right-most entry on the page.
|
| +**
|
| +** The pSpace buffer is used to store a temporary copy of the divider
|
| +** cell that will be inserted into pParent. Such a cell consists of a 4
|
| +** byte page number followed by a variable length integer. In other
|
| +** words, at most 13 bytes. Hence the pSpace buffer must be at
|
| +** least 13 bytes in size.
|
| +*/
|
| +static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
|
| + BtShared *const pBt = pPage->pBt; /* B-Tree Database */
|
| + MemPage *pNew; /* Newly allocated page */
|
| + int rc; /* Return Code */
|
| + Pgno pgnoNew; /* Page number of pNew */
|
| +
|
| + assert( sqlite3_mutex_held(pPage->pBt->mutex) );
|
| + assert( sqlite3PagerIswriteable(pParent->pDbPage) );
|
| + assert( pPage->nOverflow==1 );
|
| +
|
| + /* This error condition is now caught prior to reaching this function */
|
| + if( NEVER(pPage->nCell==0) ) return SQLITE_CORRUPT_BKPT;
|
| +
|
| + /* Allocate a new page. This page will become the right-sibling of
|
| + ** pPage. Make the parent page writable, so that the new divider cell
|
| + ** may be inserted. If both these operations are successful, proceed.
|
| + */
|
| + rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
|
| +
|
| + if( rc==SQLITE_OK ){
|
| +
|
| + u8 *pOut = &pSpace[4];
|
| + u8 *pCell = pPage->apOvfl[0];
|
| + u16 szCell = pPage->xCellSize(pPage, pCell);
|
| + u8 *pStop;
|
| +
|
| + assert( sqlite3PagerIswriteable(pNew->pDbPage) );
|
| + assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
|
| + zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
|
| + rc = rebuildPage(pNew, 1, &pCell, &szCell);
|
| + if( NEVER(rc) ) return rc;
|
| + pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;
|
| +
|
| + /* If this is an auto-vacuum database, update the pointer map
|
| + ** with entries for the new page, and any pointer from the
|
| + ** cell on the page to an overflow page. If either of these
|
| + ** operations fails, the return code is set, but the contents
|
| + ** of the parent page are still manipulated by thh code below.
|
| + ** That is Ok, at this point the parent page is guaranteed to
|
| + ** be marked as dirty. Returning an error code will cause a
|
| + ** rollback, undoing any changes made to the parent page.
|
| + */
|
| + if( ISAUTOVACUUM ){
|
| + ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno, &rc);
|
| + if( szCell>pNew->minLocal ){
|
| + ptrmapPutOvflPtr(pNew, pCell, &rc);
|
| + }
|
| + }
|
| +
|
| + /* Create a divider cell to insert into pParent. The divider cell
|
| + ** consists of a 4-byte page number (the page number of pPage) and
|
| + ** a variable length key value (which must be the same value as the
|
| + ** largest key on pPage).
|
| + **
|
| + ** To find the largest key value on pPage, first find the right-most
|
| + ** cell on pPage. The first two fields of this cell are the
|
| + ** record-length (a variable length integer at most 32-bits in size)
|
| + ** and the key value (a variable length integer, may have any value).
|
| + ** The first of the while(...) loops below skips over the record-length
|
| + ** field. The second while(...) loop copies the key value from the
|
| + ** cell on pPage into the pSpace buffer.
|
| + */
|
| + pCell = findCell(pPage, pPage->nCell-1);
|
| + pStop = &pCell[9];
|
| + while( (*(pCell++)&0x80) && pCell<pStop );
|
| + pStop = &pCell[9];
|
| + while( ((*(pOut++) = *(pCell++))&0x80) && pCell<pStop );
|
| +
|
| + /* Insert the new divider cell into pParent. */
|
| + if( rc==SQLITE_OK ){
|
| + insertCell(pParent, pParent->nCell, pSpace, (int)(pOut-pSpace),
|
| + 0, pPage->pgno, &rc);
|
| + }
|
| +
|
| + /* Set the right-child pointer of pParent to point to the new page. */
|
| + put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew);
|
| +
|
| + /* Release the reference to the new page. */
|
| + releasePage(pNew);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +#endif /* SQLITE_OMIT_QUICKBALANCE */
|
| +
|
| +#if 0
|
| +/*
|
| +** This function does not contribute anything to the operation of SQLite.
|
| +** it is sometimes activated temporarily while debugging code responsible
|
| +** for setting pointer-map entries.
|
| +*/
|
| +static int ptrmapCheckPages(MemPage **apPage, int nPage){
|
| + int i, j;
|
| + for(i=0; i<nPage; i++){
|
| + Pgno n;
|
| + u8 e;
|
| + MemPage *pPage = apPage[i];
|
| + BtShared *pBt = pPage->pBt;
|
| + assert( pPage->isInit );
|
| +
|
| + for(j=0; j<pPage->nCell; j++){
|
| + CellInfo info;
|
| + u8 *z;
|
| +
|
| + z = findCell(pPage, j);
|
| + pPage->xParseCell(pPage, z, &info);
|
| + if( info.nLocal<info.nPayload ){
|
| + Pgno ovfl = get4byte(&z[info.nSize-4]);
|
| + ptrmapGet(pBt, ovfl, &e, &n);
|
| + assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 );
|
| + }
|
| + if( !pPage->leaf ){
|
| + Pgno child = get4byte(z);
|
| + ptrmapGet(pBt, child, &e, &n);
|
| + assert( n==pPage->pgno && e==PTRMAP_BTREE );
|
| + }
|
| + }
|
| + if( !pPage->leaf ){
|
| + Pgno child = get4byte(&pPage->aData[pPage->hdrOffset+8]);
|
| + ptrmapGet(pBt, child, &e, &n);
|
| + assert( n==pPage->pgno && e==PTRMAP_BTREE );
|
| + }
|
| + }
|
| + return 1;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** This function is used to copy the contents of the b-tree node stored
|
| +** on page pFrom to page pTo. If page pFrom was not a leaf page, then
|
| +** the pointer-map entries for each child page are updated so that the
|
| +** parent page stored in the pointer map is page pTo. If pFrom contained
|
| +** any cells with overflow page pointers, then the corresponding pointer
|
| +** map entries are also updated so that the parent page is page pTo.
|
| +**
|
| +** If pFrom is currently carrying any overflow cells (entries in the
|
| +** MemPage.apOvfl[] array), they are not copied to pTo.
|
| +**
|
| +** Before returning, page pTo is reinitialized using btreeInitPage().
|
| +**
|
| +** The performance of this function is not critical. It is only used by
|
| +** the balance_shallower() and balance_deeper() procedures, neither of
|
| +** which are called often under normal circumstances.
|
| +*/
|
| +static void copyNodeContent(MemPage *pFrom, MemPage *pTo, int *pRC){
|
| + if( (*pRC)==SQLITE_OK ){
|
| + BtShared * const pBt = pFrom->pBt;
|
| + u8 * const aFrom = pFrom->aData;
|
| + u8 * const aTo = pTo->aData;
|
| + int const iFromHdr = pFrom->hdrOffset;
|
| + int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
|
| + int rc;
|
| + int iData;
|
| +
|
| +
|
| + assert( pFrom->isInit );
|
| + assert( pFrom->nFree>=iToHdr );
|
| + assert( get2byte(&aFrom[iFromHdr+5]) <= (int)pBt->usableSize );
|
| +
|
| + /* Copy the b-tree node content from page pFrom to page pTo. */
|
| + iData = get2byte(&aFrom[iFromHdr+5]);
|
| + memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
|
| + memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
|
| +
|
| + /* Reinitialize page pTo so that the contents of the MemPage structure
|
| + ** match the new data. The initialization of pTo can actually fail under
|
| + ** fairly obscure circumstances, even though it is a copy of initialized
|
| + ** page pFrom.
|
| + */
|
| + pTo->isInit = 0;
|
| + rc = btreeInitPage(pTo);
|
| + if( rc!=SQLITE_OK ){
|
| + *pRC = rc;
|
| + return;
|
| + }
|
| +
|
| + /* If this is an auto-vacuum database, update the pointer-map entries
|
| + ** for any b-tree or overflow pages that pTo now contains the pointers to.
|
| + */
|
| + if( ISAUTOVACUUM ){
|
| + *pRC = setChildPtrmaps(pTo);
|
| + }
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** This routine redistributes cells on the iParentIdx'th child of pParent
|
| +** (hereafter "the page") and up to 2 siblings so that all pages have about the
|
| +** same amount of free space. Usually a single sibling on either side of the
|
| +** page are used in the balancing, though both siblings might come from one
|
| +** side if the page is the first or last child of its parent. If the page
|
| +** has fewer than 2 siblings (something which can only happen if the page
|
| +** is a root page or a child of a root page) then all available siblings
|
| +** participate in the balancing.
|
| +**
|
| +** The number of siblings of the page might be increased or decreased by
|
| +** one or two in an effort to keep pages nearly full but not over full.
|
| +**
|
| +** Note that when this routine is called, some of the cells on the page
|
| +** might not actually be stored in MemPage.aData[]. This can happen
|
| +** if the page is overfull. This routine ensures that all cells allocated
|
| +** to the page and its siblings fit into MemPage.aData[] before returning.
|
| +**
|
| +** In the course of balancing the page and its siblings, cells may be
|
| +** inserted into or removed from the parent page (pParent). Doing so
|
| +** may cause the parent page to become overfull or underfull. If this
|
| +** happens, it is the responsibility of the caller to invoke the correct
|
| +** balancing routine to fix this problem (see the balance() routine).
|
| +**
|
| +** If this routine fails for any reason, it might leave the database
|
| +** in a corrupted state. So if this routine fails, the database should
|
| +** be rolled back.
|
| +**
|
| +** The third argument to this function, aOvflSpace, is a pointer to a
|
| +** buffer big enough to hold one page. If while inserting cells into the parent
|
| +** page (pParent) the parent page becomes overfull, this buffer is
|
| +** used to store the parent's overflow cells. Because this function inserts
|
| +** a maximum of four divider cells into the parent page, and the maximum
|
| +** size of a cell stored within an internal node is always less than 1/4
|
| +** of the page-size, the aOvflSpace[] buffer is guaranteed to be large
|
| +** enough for all overflow cells.
|
| +**
|
| +** If aOvflSpace is set to a null pointer, this function returns
|
| +** SQLITE_NOMEM.
|
| +*/
|
| +static int balance_nonroot(
|
| + MemPage *pParent, /* Parent page of siblings being balanced */
|
| + int iParentIdx, /* Index of "the page" in pParent */
|
| + u8 *aOvflSpace, /* page-size bytes of space for parent ovfl */
|
| + int isRoot, /* True if pParent is a root-page */
|
| + int bBulk /* True if this call is part of a bulk load */
|
| +){
|
| + BtShared *pBt; /* The whole database */
|
| + int nMaxCells = 0; /* Allocated size of apCell, szCell, aFrom. */
|
| + int nNew = 0; /* Number of pages in apNew[] */
|
| + int nOld; /* Number of pages in apOld[] */
|
| + int i, j, k; /* Loop counters */
|
| + int nxDiv; /* Next divider slot in pParent->aCell[] */
|
| + int rc = SQLITE_OK; /* The return code */
|
| + u16 leafCorrection; /* 4 if pPage is a leaf. 0 if not */
|
| + int leafData; /* True if pPage is a leaf of a LEAFDATA tree */
|
| + int usableSpace; /* Bytes in pPage beyond the header */
|
| + int pageFlags; /* Value of pPage->aData[0] */
|
| + int iSpace1 = 0; /* First unused byte of aSpace1[] */
|
| + int iOvflSpace = 0; /* First unused byte of aOvflSpace[] */
|
| + int szScratch; /* Size of scratch memory requested */
|
| + MemPage *apOld[NB]; /* pPage and up to two siblings */
|
| + MemPage *apNew[NB+2]; /* pPage and up to NB siblings after balancing */
|
| + u8 *pRight; /* Location in parent of right-sibling pointer */
|
| + u8 *apDiv[NB-1]; /* Divider cells in pParent */
|
| + int cntNew[NB+2]; /* Index in b.paCell[] of cell after i-th page */
|
| + int cntOld[NB+2]; /* Old index in b.apCell[] */
|
| + int szNew[NB+2]; /* Combined size of cells placed on i-th page */
|
| + u8 *aSpace1; /* Space for copies of dividers cells */
|
| + Pgno pgno; /* Temp var to store a page number in */
|
| + u8 abDone[NB+2]; /* True after i'th new page is populated */
|
| + Pgno aPgno[NB+2]; /* Page numbers of new pages before shuffling */
|
| + Pgno aPgOrder[NB+2]; /* Copy of aPgno[] used for sorting pages */
|
| + u16 aPgFlags[NB+2]; /* flags field of new pages before shuffling */
|
| + CellArray b; /* Parsed information on cells being balanced */
|
| +
|
| + memset(abDone, 0, sizeof(abDone));
|
| + b.nCell = 0;
|
| + b.apCell = 0;
|
| + pBt = pParent->pBt;
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + assert( sqlite3PagerIswriteable(pParent->pDbPage) );
|
| +
|
| +#if 0
|
| + TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
|
| +#endif
|
| +
|
| + /* At this point pParent may have at most one overflow cell. And if
|
| + ** this overflow cell is present, it must be the cell with
|
| + ** index iParentIdx. This scenario comes about when this function
|
| + ** is called (indirectly) from sqlite3BtreeDelete().
|
| + */
|
| + assert( pParent->nOverflow==0 || pParent->nOverflow==1 );
|
| + assert( pParent->nOverflow==0 || pParent->aiOvfl[0]==iParentIdx );
|
| +
|
| + if( !aOvflSpace ){
|
| + return SQLITE_NOMEM_BKPT;
|
| + }
|
| +
|
| + /* Find the sibling pages to balance. Also locate the cells in pParent
|
| + ** that divide the siblings. An attempt is made to find NN siblings on
|
| + ** either side of pPage. More siblings are taken from one side, however,
|
| + ** if there are fewer than NN siblings on the other side. If pParent
|
| + ** has NB or fewer children then all children of pParent are taken.
|
| + **
|
| + ** This loop also drops the divider cells from the parent page. This
|
| + ** way, the remainder of the function does not have to deal with any
|
| + ** overflow cells in the parent page, since if any existed they will
|
| + ** have already been removed.
|
| + */
|
| + i = pParent->nOverflow + pParent->nCell;
|
| + if( i<2 ){
|
| + nxDiv = 0;
|
| + }else{
|
| + assert( bBulk==0 || bBulk==1 );
|
| + if( iParentIdx==0 ){
|
| + nxDiv = 0;
|
| + }else if( iParentIdx==i ){
|
| + nxDiv = i-2+bBulk;
|
| + }else{
|
| + nxDiv = iParentIdx-1;
|
| + }
|
| + i = 2-bBulk;
|
| + }
|
| + nOld = i+1;
|
| + if( (i+nxDiv-pParent->nOverflow)==pParent->nCell ){
|
| + pRight = &pParent->aData[pParent->hdrOffset+8];
|
| + }else{
|
| + pRight = findCell(pParent, i+nxDiv-pParent->nOverflow);
|
| + }
|
| + pgno = get4byte(pRight);
|
| + while( 1 ){
|
| + rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0);
|
| + if( rc ){
|
| + memset(apOld, 0, (i+1)*sizeof(MemPage*));
|
| + goto balance_cleanup;
|
| + }
|
| + nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
|
| + if( (i--)==0 ) break;
|
| +
|
| + if( pParent->nOverflow && i+nxDiv==pParent->aiOvfl[0] ){
|
| + apDiv[i] = pParent->apOvfl[0];
|
| + pgno = get4byte(apDiv[i]);
|
| + szNew[i] = pParent->xCellSize(pParent, apDiv[i]);
|
| + pParent->nOverflow = 0;
|
| + }else{
|
| + apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow);
|
| + pgno = get4byte(apDiv[i]);
|
| + szNew[i] = pParent->xCellSize(pParent, apDiv[i]);
|
| +
|
| + /* Drop the cell from the parent page. apDiv[i] still points to
|
| + ** the cell within the parent, even though it has been dropped.
|
| + ** This is safe because dropping a cell only overwrites the first
|
| + ** four bytes of it, and this function does not need the first
|
| + ** four bytes of the divider cell. So the pointer is safe to use
|
| + ** later on.
|
| + **
|
| + ** But not if we are in secure-delete mode. In secure-delete mode,
|
| + ** the dropCell() routine will overwrite the entire cell with zeroes.
|
| + ** In this case, temporarily copy the cell into the aOvflSpace[]
|
| + ** buffer. It will be copied out again as soon as the aSpace[] buffer
|
| + ** is allocated. */
|
| + if( pBt->btsFlags & BTS_SECURE_DELETE ){
|
| + int iOff;
|
| +
|
| + iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData);
|
| + if( (iOff+szNew[i])>(int)pBt->usableSize ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + memset(apOld, 0, (i+1)*sizeof(MemPage*));
|
| + goto balance_cleanup;
|
| + }else{
|
| + memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
|
| + apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
|
| + }
|
| + }
|
| + dropCell(pParent, i+nxDiv-pParent->nOverflow, szNew[i], &rc);
|
| + }
|
| + }
|
| +
|
| + /* Make nMaxCells a multiple of 4 in order to preserve 8-byte
|
| + ** alignment */
|
| + nMaxCells = (nMaxCells + 3)&~3;
|
| +
|
| + /*
|
| + ** Allocate space for memory structures
|
| + */
|
| + szScratch =
|
| + nMaxCells*sizeof(u8*) /* b.apCell */
|
| + + nMaxCells*sizeof(u16) /* b.szCell */
|
| + + pBt->pageSize; /* aSpace1 */
|
| +
|
| + /* EVIDENCE-OF: R-28375-38319 SQLite will never request a scratch buffer
|
| + ** that is more than 6 times the database page size. */
|
| + assert( szScratch<=6*(int)pBt->pageSize );
|
| + b.apCell = sqlite3ScratchMalloc( szScratch );
|
| + if( b.apCell==0 ){
|
| + rc = SQLITE_NOMEM_BKPT;
|
| + goto balance_cleanup;
|
| + }
|
| + b.szCell = (u16*)&b.apCell[nMaxCells];
|
| + aSpace1 = (u8*)&b.szCell[nMaxCells];
|
| + assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );
|
| +
|
| + /*
|
| + ** Load pointers to all cells on sibling pages and the divider cells
|
| + ** into the local b.apCell[] array. Make copies of the divider cells
|
| + ** into space obtained from aSpace1[]. The divider cells have already
|
| + ** been removed from pParent.
|
| + **
|
| + ** If the siblings are on leaf pages, then the child pointers of the
|
| + ** divider cells are stripped from the cells before they are copied
|
| + ** into aSpace1[]. In this way, all cells in b.apCell[] are without
|
| + ** child pointers. If siblings are not leaves, then all cell in
|
| + ** b.apCell[] include child pointers. Either way, all cells in b.apCell[]
|
| + ** are alike.
|
| + **
|
| + ** leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf.
|
| + ** leafData: 1 if pPage holds key+data and pParent holds only keys.
|
| + */
|
| + b.pRef = apOld[0];
|
| + leafCorrection = b.pRef->leaf*4;
|
| + leafData = b.pRef->intKeyLeaf;
|
| + for(i=0; i<nOld; i++){
|
| + MemPage *pOld = apOld[i];
|
| + int limit = pOld->nCell;
|
| + u8 *aData = pOld->aData;
|
| + u16 maskPage = pOld->maskPage;
|
| + u8 *piCell = aData + pOld->cellOffset;
|
| + u8 *piEnd;
|
| +
|
| + /* Verify that all sibling pages are of the same "type" (table-leaf,
|
| + ** table-interior, index-leaf, or index-interior).
|
| + */
|
| + if( pOld->aData[0]!=apOld[0]->aData[0] ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto balance_cleanup;
|
| + }
|
| +
|
| + /* Load b.apCell[] with pointers to all cells in pOld. If pOld
|
| + ** constains overflow cells, include them in the b.apCell[] array
|
| + ** in the correct spot.
|
| + **
|
| + ** Note that when there are multiple overflow cells, it is always the
|
| + ** case that they are sequential and adjacent. This invariant arises
|
| + ** because multiple overflows can only occurs when inserting divider
|
| + ** cells into a parent on a prior balance, and divider cells are always
|
| + ** adjacent and are inserted in order. There is an assert() tagged
|
| + ** with "NOTE 1" in the overflow cell insertion loop to prove this
|
| + ** invariant.
|
| + **
|
| + ** This must be done in advance. Once the balance starts, the cell
|
| + ** offset section of the btree page will be overwritten and we will no
|
| + ** long be able to find the cells if a pointer to each cell is not saved
|
| + ** first.
|
| + */
|
| + memset(&b.szCell[b.nCell], 0, sizeof(b.szCell[0])*(limit+pOld->nOverflow));
|
| + if( pOld->nOverflow>0 ){
|
| + limit = pOld->aiOvfl[0];
|
| + for(j=0; j<limit; j++){
|
| + b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell));
|
| + piCell += 2;
|
| + b.nCell++;
|
| + }
|
| + for(k=0; k<pOld->nOverflow; k++){
|
| + assert( k==0 || pOld->aiOvfl[k-1]+1==pOld->aiOvfl[k] );/* NOTE 1 */
|
| + b.apCell[b.nCell] = pOld->apOvfl[k];
|
| + b.nCell++;
|
| + }
|
| + }
|
| + piEnd = aData + pOld->cellOffset + 2*pOld->nCell;
|
| + while( piCell<piEnd ){
|
| + assert( b.nCell<nMaxCells );
|
| + b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell));
|
| + piCell += 2;
|
| + b.nCell++;
|
| + }
|
| +
|
| + cntOld[i] = b.nCell;
|
| + if( i<nOld-1 && !leafData){
|
| + u16 sz = (u16)szNew[i];
|
| + u8 *pTemp;
|
| + assert( b.nCell<nMaxCells );
|
| + b.szCell[b.nCell] = sz;
|
| + pTemp = &aSpace1[iSpace1];
|
| + iSpace1 += sz;
|
| + assert( sz<=pBt->maxLocal+23 );
|
| + assert( iSpace1 <= (int)pBt->pageSize );
|
| + memcpy(pTemp, apDiv[i], sz);
|
| + b.apCell[b.nCell] = pTemp+leafCorrection;
|
| + assert( leafCorrection==0 || leafCorrection==4 );
|
| + b.szCell[b.nCell] = b.szCell[b.nCell] - leafCorrection;
|
| + if( !pOld->leaf ){
|
| + assert( leafCorrection==0 );
|
| + assert( pOld->hdrOffset==0 );
|
| + /* The right pointer of the child page pOld becomes the left
|
| + ** pointer of the divider cell */
|
| + memcpy(b.apCell[b.nCell], &pOld->aData[8], 4);
|
| + }else{
|
| + assert( leafCorrection==4 );
|
| + while( b.szCell[b.nCell]<4 ){
|
| + /* Do not allow any cells smaller than 4 bytes. If a smaller cell
|
| + ** does exist, pad it with 0x00 bytes. */
|
| + assert( b.szCell[b.nCell]==3 || CORRUPT_DB );
|
| + assert( b.apCell[b.nCell]==&aSpace1[iSpace1-3] || CORRUPT_DB );
|
| + aSpace1[iSpace1++] = 0x00;
|
| + b.szCell[b.nCell]++;
|
| + }
|
| + }
|
| + b.nCell++;
|
| + }
|
| + }
|
| +
|
| + /*
|
| + ** Figure out the number of pages needed to hold all b.nCell cells.
|
| + ** Store this number in "k". Also compute szNew[] which is the total
|
| + ** size of all cells on the i-th page and cntNew[] which is the index
|
| + ** in b.apCell[] of the cell that divides page i from page i+1.
|
| + ** cntNew[k] should equal b.nCell.
|
| + **
|
| + ** Values computed by this block:
|
| + **
|
| + ** k: The total number of sibling pages
|
| + ** szNew[i]: Spaced used on the i-th sibling page.
|
| + ** cntNew[i]: Index in b.apCell[] and b.szCell[] for the first cell to
|
| + ** the right of the i-th sibling page.
|
| + ** usableSpace: Number of bytes of space available on each sibling.
|
| + **
|
| + */
|
| + usableSpace = pBt->usableSize - 12 + leafCorrection;
|
| + for(i=0; i<nOld; i++){
|
| + MemPage *p = apOld[i];
|
| + szNew[i] = usableSpace - p->nFree;
|
| + for(j=0; j<p->nOverflow; j++){
|
| + szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]);
|
| + }
|
| + cntNew[i] = cntOld[i];
|
| + }
|
| + k = nOld;
|
| + for(i=0; i<k; i++){
|
| + int sz;
|
| + while( szNew[i]>usableSpace ){
|
| + if( i+1>=k ){
|
| + k = i+2;
|
| + if( k>NB+2 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
|
| + szNew[k-1] = 0;
|
| + cntNew[k-1] = b.nCell;
|
| + }
|
| + sz = 2 + cachedCellSize(&b, cntNew[i]-1);
|
| + szNew[i] -= sz;
|
| + if( !leafData ){
|
| + if( cntNew[i]<b.nCell ){
|
| + sz = 2 + cachedCellSize(&b, cntNew[i]);
|
| + }else{
|
| + sz = 0;
|
| + }
|
| + }
|
| + szNew[i+1] += sz;
|
| + cntNew[i]--;
|
| + }
|
| + while( cntNew[i]<b.nCell ){
|
| + sz = 2 + cachedCellSize(&b, cntNew[i]);
|
| + if( szNew[i]+sz>usableSpace ) break;
|
| + szNew[i] += sz;
|
| + cntNew[i]++;
|
| + if( !leafData ){
|
| + if( cntNew[i]<b.nCell ){
|
| + sz = 2 + cachedCellSize(&b, cntNew[i]);
|
| + }else{
|
| + sz = 0;
|
| + }
|
| + }
|
| + szNew[i+1] -= sz;
|
| + }
|
| + if( cntNew[i]>=b.nCell ){
|
| + k = i+1;
|
| + }else if( cntNew[i] <= (i>0 ? cntNew[i-1] : 0) ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto balance_cleanup;
|
| + }
|
| + }
|
| +
|
| + /*
|
| + ** The packing computed by the previous block is biased toward the siblings
|
| + ** on the left side (siblings with smaller keys). The left siblings are
|
| + ** always nearly full, while the right-most sibling might be nearly empty.
|
| + ** The next block of code attempts to adjust the packing of siblings to
|
| + ** get a better balance.
|
| + **
|
| + ** This adjustment is more than an optimization. The packing above might
|
| + ** be so out of balance as to be illegal. For example, the right-most
|
| + ** sibling might be completely empty. This adjustment is not optional.
|
| + */
|
| + for(i=k-1; i>0; i--){
|
| + int szRight = szNew[i]; /* Size of sibling on the right */
|
| + int szLeft = szNew[i-1]; /* Size of sibling on the left */
|
| + int r; /* Index of right-most cell in left sibling */
|
| + int d; /* Index of first cell to the left of right sibling */
|
| +
|
| + r = cntNew[i-1] - 1;
|
| + d = r + 1 - leafData;
|
| + (void)cachedCellSize(&b, d);
|
| + do{
|
| + assert( d<nMaxCells );
|
| + assert( r<nMaxCells );
|
| + (void)cachedCellSize(&b, r);
|
| + if( szRight!=0
|
| + && (bBulk || szRight+b.szCell[d]+2 > szLeft-(b.szCell[r]+(i==k-1?0:2)))){
|
| + break;
|
| + }
|
| + szRight += b.szCell[d] + 2;
|
| + szLeft -= b.szCell[r] + 2;
|
| + cntNew[i-1] = r;
|
| + r--;
|
| + d--;
|
| + }while( r>=0 );
|
| + szNew[i] = szRight;
|
| + szNew[i-1] = szLeft;
|
| + if( cntNew[i-1] <= (i>1 ? cntNew[i-2] : 0) ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto balance_cleanup;
|
| + }
|
| + }
|
| +
|
| + /* Sanity check: For a non-corrupt database file one of the follwing
|
| + ** must be true:
|
| + ** (1) We found one or more cells (cntNew[0])>0), or
|
| + ** (2) pPage is a virtual root page. A virtual root page is when
|
| + ** the real root page is page 1 and we are the only child of
|
| + ** that page.
|
| + */
|
| + assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) || CORRUPT_DB);
|
| + TRACE(("BALANCE: old: %d(nc=%d) %d(nc=%d) %d(nc=%d)\n",
|
| + apOld[0]->pgno, apOld[0]->nCell,
|
| + nOld>=2 ? apOld[1]->pgno : 0, nOld>=2 ? apOld[1]->nCell : 0,
|
| + nOld>=3 ? apOld[2]->pgno : 0, nOld>=3 ? apOld[2]->nCell : 0
|
| + ));
|
| +
|
| + /*
|
| + ** Allocate k new pages. Reuse old pages where possible.
|
| + */
|
| + pageFlags = apOld[0]->aData[0];
|
| + for(i=0; i<k; i++){
|
| + MemPage *pNew;
|
| + if( i<nOld ){
|
| + pNew = apNew[i] = apOld[i];
|
| + apOld[i] = 0;
|
| + rc = sqlite3PagerWrite(pNew->pDbPage);
|
| + nNew++;
|
| + if( rc ) goto balance_cleanup;
|
| + }else{
|
| + assert( i>0 );
|
| + rc = allocateBtreePage(pBt, &pNew, &pgno, (bBulk ? 1 : pgno), 0);
|
| + if( rc ) goto balance_cleanup;
|
| + zeroPage(pNew, pageFlags);
|
| + apNew[i] = pNew;
|
| + nNew++;
|
| + cntOld[i] = b.nCell;
|
| +
|
| + /* Set the pointer-map entry for the new sibling page. */
|
| + if( ISAUTOVACUUM ){
|
| + ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
|
| + if( rc!=SQLITE_OK ){
|
| + goto balance_cleanup;
|
| + }
|
| + }
|
| + }
|
| + }
|
| +
|
| + /*
|
| + ** Reassign page numbers so that the new pages are in ascending order.
|
| + ** This helps to keep entries in the disk file in order so that a scan
|
| + ** of the table is closer to a linear scan through the file. That in turn
|
| + ** helps the operating system to deliver pages from the disk more rapidly.
|
| + **
|
| + ** An O(n^2) insertion sort algorithm is used, but since n is never more
|
| + ** than (NB+2) (a small constant), that should not be a problem.
|
| + **
|
| + ** When NB==3, this one optimization makes the database about 25% faster
|
| + ** for large insertions and deletions.
|
| + */
|
| + for(i=0; i<nNew; i++){
|
| + aPgOrder[i] = aPgno[i] = apNew[i]->pgno;
|
| + aPgFlags[i] = apNew[i]->pDbPage->flags;
|
| + for(j=0; j<i; j++){
|
| + if( aPgno[j]==aPgno[i] ){
|
| + /* This branch is taken if the set of sibling pages somehow contains
|
| + ** duplicate entries. This can happen if the database is corrupt.
|
| + ** It would be simpler to detect this as part of the loop below, but
|
| + ** we do the detection here in order to avoid populating the pager
|
| + ** cache with two separate objects associated with the same
|
| + ** page number. */
|
| + assert( CORRUPT_DB );
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto balance_cleanup;
|
| + }
|
| + }
|
| + }
|
| + for(i=0; i<nNew; i++){
|
| + int iBest = 0; /* aPgno[] index of page number to use */
|
| + for(j=1; j<nNew; j++){
|
| + if( aPgOrder[j]<aPgOrder[iBest] ) iBest = j;
|
| + }
|
| + pgno = aPgOrder[iBest];
|
| + aPgOrder[iBest] = 0xffffffff;
|
| + if( iBest!=i ){
|
| + if( iBest>i ){
|
| + sqlite3PagerRekey(apNew[iBest]->pDbPage, pBt->nPage+iBest+1, 0);
|
| + }
|
| + sqlite3PagerRekey(apNew[i]->pDbPage, pgno, aPgFlags[iBest]);
|
| + apNew[i]->pgno = pgno;
|
| + }
|
| + }
|
| +
|
| + TRACE(("BALANCE: new: %d(%d nc=%d) %d(%d nc=%d) %d(%d nc=%d) "
|
| + "%d(%d nc=%d) %d(%d nc=%d)\n",
|
| + apNew[0]->pgno, szNew[0], cntNew[0],
|
| + nNew>=2 ? apNew[1]->pgno : 0, nNew>=2 ? szNew[1] : 0,
|
| + nNew>=2 ? cntNew[1] - cntNew[0] - !leafData : 0,
|
| + nNew>=3 ? apNew[2]->pgno : 0, nNew>=3 ? szNew[2] : 0,
|
| + nNew>=3 ? cntNew[2] - cntNew[1] - !leafData : 0,
|
| + nNew>=4 ? apNew[3]->pgno : 0, nNew>=4 ? szNew[3] : 0,
|
| + nNew>=4 ? cntNew[3] - cntNew[2] - !leafData : 0,
|
| + nNew>=5 ? apNew[4]->pgno : 0, nNew>=5 ? szNew[4] : 0,
|
| + nNew>=5 ? cntNew[4] - cntNew[3] - !leafData : 0
|
| + ));
|
| +
|
| + assert( sqlite3PagerIswriteable(pParent->pDbPage) );
|
| + put4byte(pRight, apNew[nNew-1]->pgno);
|
| +
|
| + /* If the sibling pages are not leaves, ensure that the right-child pointer
|
| + ** of the right-most new sibling page is set to the value that was
|
| + ** originally in the same field of the right-most old sibling page. */
|
| + if( (pageFlags & PTF_LEAF)==0 && nOld!=nNew ){
|
| + MemPage *pOld = (nNew>nOld ? apNew : apOld)[nOld-1];
|
| + memcpy(&apNew[nNew-1]->aData[8], &pOld->aData[8], 4);
|
| + }
|
| +
|
| + /* Make any required updates to pointer map entries associated with
|
| + ** cells stored on sibling pages following the balance operation. Pointer
|
| + ** map entries associated with divider cells are set by the insertCell()
|
| + ** routine. The associated pointer map entries are:
|
| + **
|
| + ** a) if the cell contains a reference to an overflow chain, the
|
| + ** entry associated with the first page in the overflow chain, and
|
| + **
|
| + ** b) if the sibling pages are not leaves, the child page associated
|
| + ** with the cell.
|
| + **
|
| + ** If the sibling pages are not leaves, then the pointer map entry
|
| + ** associated with the right-child of each sibling may also need to be
|
| + ** updated. This happens below, after the sibling pages have been
|
| + ** populated, not here.
|
| + */
|
| + if( ISAUTOVACUUM ){
|
| + MemPage *pNew = apNew[0];
|
| + u8 *aOld = pNew->aData;
|
| + int cntOldNext = pNew->nCell + pNew->nOverflow;
|
| + int usableSize = pBt->usableSize;
|
| + int iNew = 0;
|
| + int iOld = 0;
|
| +
|
| + for(i=0; i<b.nCell; i++){
|
| + u8 *pCell = b.apCell[i];
|
| + if( i==cntOldNext ){
|
| + MemPage *pOld = (++iOld)<nNew ? apNew[iOld] : apOld[iOld];
|
| + cntOldNext += pOld->nCell + pOld->nOverflow + !leafData;
|
| + aOld = pOld->aData;
|
| + }
|
| + if( i==cntNew[iNew] ){
|
| + pNew = apNew[++iNew];
|
| + if( !leafData ) continue;
|
| + }
|
| +
|
| + /* Cell pCell is destined for new sibling page pNew. Originally, it
|
| + ** was either part of sibling page iOld (possibly an overflow cell),
|
| + ** or else the divider cell to the left of sibling page iOld. So,
|
| + ** if sibling page iOld had the same page number as pNew, and if
|
| + ** pCell really was a part of sibling page iOld (not a divider or
|
| + ** overflow cell), we can skip updating the pointer map entries. */
|
| + if( iOld>=nNew
|
| + || pNew->pgno!=aPgno[iOld]
|
| + || !SQLITE_WITHIN(pCell,aOld,&aOld[usableSize])
|
| + ){
|
| + if( !leafCorrection ){
|
| + ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
|
| + }
|
| + if( cachedCellSize(&b,i)>pNew->minLocal ){
|
| + ptrmapPutOvflPtr(pNew, pCell, &rc);
|
| + }
|
| + if( rc ) goto balance_cleanup;
|
| + }
|
| + }
|
| + }
|
| +
|
| + /* Insert new divider cells into pParent. */
|
| + for(i=0; i<nNew-1; i++){
|
| + u8 *pCell;
|
| + u8 *pTemp;
|
| + int sz;
|
| + MemPage *pNew = apNew[i];
|
| + j = cntNew[i];
|
| +
|
| + assert( j<nMaxCells );
|
| + assert( b.apCell[j]!=0 );
|
| + pCell = b.apCell[j];
|
| + sz = b.szCell[j] + leafCorrection;
|
| + pTemp = &aOvflSpace[iOvflSpace];
|
| + if( !pNew->leaf ){
|
| + memcpy(&pNew->aData[8], pCell, 4);
|
| + }else if( leafData ){
|
| + /* If the tree is a leaf-data tree, and the siblings are leaves,
|
| + ** then there is no divider cell in b.apCell[]. Instead, the divider
|
| + ** cell consists of the integer key for the right-most cell of
|
| + ** the sibling-page assembled above only.
|
| + */
|
| + CellInfo info;
|
| + j--;
|
| + pNew->xParseCell(pNew, b.apCell[j], &info);
|
| + pCell = pTemp;
|
| + sz = 4 + putVarint(&pCell[4], info.nKey);
|
| + pTemp = 0;
|
| + }else{
|
| + pCell -= 4;
|
| + /* Obscure case for non-leaf-data trees: If the cell at pCell was
|
| + ** previously stored on a leaf node, and its reported size was 4
|
| + ** bytes, then it may actually be smaller than this
|
| + ** (see btreeParseCellPtr(), 4 bytes is the minimum size of
|
| + ** any cell). But it is important to pass the correct size to
|
| + ** insertCell(), so reparse the cell now.
|
| + **
|
| + ** This can only happen for b-trees used to evaluate "IN (SELECT ...)"
|
| + ** and WITHOUT ROWID tables with exactly one column which is the
|
| + ** primary key.
|
| + */
|
| + if( b.szCell[j]==4 ){
|
| + assert(leafCorrection==4);
|
| + sz = pParent->xCellSize(pParent, pCell);
|
| + }
|
| + }
|
| + iOvflSpace += sz;
|
| + assert( sz<=pBt->maxLocal+23 );
|
| + assert( iOvflSpace <= (int)pBt->pageSize );
|
| + insertCell(pParent, nxDiv+i, pCell, sz, pTemp, pNew->pgno, &rc);
|
| + if( rc!=SQLITE_OK ) goto balance_cleanup;
|
| + assert( sqlite3PagerIswriteable(pParent->pDbPage) );
|
| + }
|
| +
|
| + /* Now update the actual sibling pages. The order in which they are updated
|
| + ** is important, as this code needs to avoid disrupting any page from which
|
| + ** cells may still to be read. In practice, this means:
|
| + **
|
| + ** (1) If cells are moving left (from apNew[iPg] to apNew[iPg-1])
|
| + ** then it is not safe to update page apNew[iPg] until after
|
| + ** the left-hand sibling apNew[iPg-1] has been updated.
|
| + **
|
| + ** (2) If cells are moving right (from apNew[iPg] to apNew[iPg+1])
|
| + ** then it is not safe to update page apNew[iPg] until after
|
| + ** the right-hand sibling apNew[iPg+1] has been updated.
|
| + **
|
| + ** If neither of the above apply, the page is safe to update.
|
| + **
|
| + ** The iPg value in the following loop starts at nNew-1 goes down
|
| + ** to 0, then back up to nNew-1 again, thus making two passes over
|
| + ** the pages. On the initial downward pass, only condition (1) above
|
| + ** needs to be tested because (2) will always be true from the previous
|
| + ** step. On the upward pass, both conditions are always true, so the
|
| + ** upwards pass simply processes pages that were missed on the downward
|
| + ** pass.
|
| + */
|
| + for(i=1-nNew; i<nNew; i++){
|
| + int iPg = i<0 ? -i : i;
|
| + assert( iPg>=0 && iPg<nNew );
|
| + if( abDone[iPg] ) continue; /* Skip pages already processed */
|
| + if( i>=0 /* On the upwards pass, or... */
|
| + || cntOld[iPg-1]>=cntNew[iPg-1] /* Condition (1) is true */
|
| + ){
|
| + int iNew;
|
| + int iOld;
|
| + int nNewCell;
|
| +
|
| + /* Verify condition (1): If cells are moving left, update iPg
|
| + ** only after iPg-1 has already been updated. */
|
| + assert( iPg==0 || cntOld[iPg-1]>=cntNew[iPg-1] || abDone[iPg-1] );
|
| +
|
| + /* Verify condition (2): If cells are moving right, update iPg
|
| + ** only after iPg+1 has already been updated. */
|
| + assert( cntNew[iPg]>=cntOld[iPg] || abDone[iPg+1] );
|
| +
|
| + if( iPg==0 ){
|
| + iNew = iOld = 0;
|
| + nNewCell = cntNew[0];
|
| + }else{
|
| + iOld = iPg<nOld ? (cntOld[iPg-1] + !leafData) : b.nCell;
|
| + iNew = cntNew[iPg-1] + !leafData;
|
| + nNewCell = cntNew[iPg] - iNew;
|
| + }
|
| +
|
| + rc = editPage(apNew[iPg], iOld, iNew, nNewCell, &b);
|
| + if( rc ) goto balance_cleanup;
|
| + abDone[iPg]++;
|
| + apNew[iPg]->nFree = usableSpace-szNew[iPg];
|
| + assert( apNew[iPg]->nOverflow==0 );
|
| + assert( apNew[iPg]->nCell==nNewCell );
|
| + }
|
| + }
|
| +
|
| + /* All pages have been processed exactly once */
|
| + assert( memcmp(abDone, "\01\01\01\01\01", nNew)==0 );
|
| +
|
| + assert( nOld>0 );
|
| + assert( nNew>0 );
|
| +
|
| + if( isRoot && pParent->nCell==0 && pParent->hdrOffset<=apNew[0]->nFree ){
|
| + /* The root page of the b-tree now contains no cells. The only sibling
|
| + ** page is the right-child of the parent. Copy the contents of the
|
| + ** child page into the parent, decreasing the overall height of the
|
| + ** b-tree structure by one. This is described as the "balance-shallower"
|
| + ** sub-algorithm in some documentation.
|
| + **
|
| + ** If this is an auto-vacuum database, the call to copyNodeContent()
|
| + ** sets all pointer-map entries corresponding to database image pages
|
| + ** for which the pointer is stored within the content being copied.
|
| + **
|
| + ** It is critical that the child page be defragmented before being
|
| + ** copied into the parent, because if the parent is page 1 then it will
|
| + ** by smaller than the child due to the database header, and so all the
|
| + ** free space needs to be up front.
|
| + */
|
| + assert( nNew==1 || CORRUPT_DB );
|
| + rc = defragmentPage(apNew[0]);
|
| + testcase( rc!=SQLITE_OK );
|
| + assert( apNew[0]->nFree ==
|
| + (get2byte(&apNew[0]->aData[5])-apNew[0]->cellOffset-apNew[0]->nCell*2)
|
| + || rc!=SQLITE_OK
|
| + );
|
| + copyNodeContent(apNew[0], pParent, &rc);
|
| + freePage(apNew[0], &rc);
|
| + }else if( ISAUTOVACUUM && !leafCorrection ){
|
| + /* Fix the pointer map entries associated with the right-child of each
|
| + ** sibling page. All other pointer map entries have already been taken
|
| + ** care of. */
|
| + for(i=0; i<nNew; i++){
|
| + u32 key = get4byte(&apNew[i]->aData[8]);
|
| + ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc);
|
| + }
|
| + }
|
| +
|
| + assert( pParent->isInit );
|
| + TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n",
|
| + nOld, nNew, b.nCell));
|
| +
|
| + /* Free any old pages that were not reused as new pages.
|
| + */
|
| + for(i=nNew; i<nOld; i++){
|
| + freePage(apOld[i], &rc);
|
| + }
|
| +
|
| +#if 0
|
| + if( ISAUTOVACUUM && rc==SQLITE_OK && apNew[0]->isInit ){
|
| + /* The ptrmapCheckPages() contains assert() statements that verify that
|
| + ** all pointer map pages are set correctly. This is helpful while
|
| + ** debugging. This is usually disabled because a corrupt database may
|
| + ** cause an assert() statement to fail. */
|
| + ptrmapCheckPages(apNew, nNew);
|
| + ptrmapCheckPages(&pParent, 1);
|
| + }
|
| +#endif
|
| +
|
| + /*
|
| + ** Cleanup before returning.
|
| + */
|
| +balance_cleanup:
|
| + sqlite3ScratchFree(b.apCell);
|
| + for(i=0; i<nOld; i++){
|
| + releasePage(apOld[i]);
|
| + }
|
| + for(i=0; i<nNew; i++){
|
| + releasePage(apNew[i]);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** This function is called when the root page of a b-tree structure is
|
| +** overfull (has one or more overflow pages).
|
| +**
|
| +** A new child page is allocated and the contents of the current root
|
| +** page, including overflow cells, are copied into the child. The root
|
| +** page is then overwritten to make it an empty page with the right-child
|
| +** pointer pointing to the new page.
|
| +**
|
| +** Before returning, all pointer-map entries corresponding to pages
|
| +** that the new child-page now contains pointers to are updated. The
|
| +** entry corresponding to the new right-child pointer of the root
|
| +** page is also updated.
|
| +**
|
| +** If successful, *ppChild is set to contain a reference to the child
|
| +** page and SQLITE_OK is returned. In this case the caller is required
|
| +** to call releasePage() on *ppChild exactly once. If an error occurs,
|
| +** an error code is returned and *ppChild is set to 0.
|
| +*/
|
| +static int balance_deeper(MemPage *pRoot, MemPage **ppChild){
|
| + int rc; /* Return value from subprocedures */
|
| + MemPage *pChild = 0; /* Pointer to a new child page */
|
| + Pgno pgnoChild = 0; /* Page number of the new child page */
|
| + BtShared *pBt = pRoot->pBt; /* The BTree */
|
| +
|
| + assert( pRoot->nOverflow>0 );
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| +
|
| + /* Make pRoot, the root page of the b-tree, writable. Allocate a new
|
| + ** page that will become the new right-child of pPage. Copy the contents
|
| + ** of the node stored on pRoot into the new child page.
|
| + */
|
| + rc = sqlite3PagerWrite(pRoot->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + rc = allocateBtreePage(pBt,&pChild,&pgnoChild,pRoot->pgno,0);
|
| + copyNodeContent(pRoot, pChild, &rc);
|
| + if( ISAUTOVACUUM ){
|
| + ptrmapPut(pBt, pgnoChild, PTRMAP_BTREE, pRoot->pgno, &rc);
|
| + }
|
| + }
|
| + if( rc ){
|
| + *ppChild = 0;
|
| + releasePage(pChild);
|
| + return rc;
|
| + }
|
| + assert( sqlite3PagerIswriteable(pChild->pDbPage) );
|
| + assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
|
| + assert( pChild->nCell==pRoot->nCell );
|
| +
|
| + TRACE(("BALANCE: copy root %d into %d\n", pRoot->pgno, pChild->pgno));
|
| +
|
| + /* Copy the overflow cells from pRoot to pChild */
|
| + memcpy(pChild->aiOvfl, pRoot->aiOvfl,
|
| + pRoot->nOverflow*sizeof(pRoot->aiOvfl[0]));
|
| + memcpy(pChild->apOvfl, pRoot->apOvfl,
|
| + pRoot->nOverflow*sizeof(pRoot->apOvfl[0]));
|
| + pChild->nOverflow = pRoot->nOverflow;
|
| +
|
| + /* Zero the contents of pRoot. Then install pChild as the right-child. */
|
| + zeroPage(pRoot, pChild->aData[0] & ~PTF_LEAF);
|
| + put4byte(&pRoot->aData[pRoot->hdrOffset+8], pgnoChild);
|
| +
|
| + *ppChild = pChild;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** The page that pCur currently points to has just been modified in
|
| +** some way. This function figures out if this modification means the
|
| +** tree needs to be balanced, and if so calls the appropriate balancing
|
| +** routine. Balancing routines are:
|
| +**
|
| +** balance_quick()
|
| +** balance_deeper()
|
| +** balance_nonroot()
|
| +*/
|
| +static int balance(BtCursor *pCur){
|
| + int rc = SQLITE_OK;
|
| + const int nMin = pCur->pBt->usableSize * 2 / 3;
|
| + u8 aBalanceQuickSpace[13];
|
| + u8 *pFree = 0;
|
| +
|
| + VVA_ONLY( int balance_quick_called = 0 );
|
| + VVA_ONLY( int balance_deeper_called = 0 );
|
| +
|
| + do {
|
| + int iPage = pCur->iPage;
|
| + MemPage *pPage = pCur->apPage[iPage];
|
| +
|
| + if( iPage==0 ){
|
| + if( pPage->nOverflow ){
|
| + /* The root page of the b-tree is overfull. In this case call the
|
| + ** balance_deeper() function to create a new child for the root-page
|
| + ** and copy the current contents of the root-page to it. The
|
| + ** next iteration of the do-loop will balance the child page.
|
| + */
|
| + assert( balance_deeper_called==0 );
|
| + VVA_ONLY( balance_deeper_called++ );
|
| + rc = balance_deeper(pPage, &pCur->apPage[1]);
|
| + if( rc==SQLITE_OK ){
|
| + pCur->iPage = 1;
|
| + pCur->aiIdx[0] = 0;
|
| + pCur->aiIdx[1] = 0;
|
| + assert( pCur->apPage[1]->nOverflow );
|
| + }
|
| + }else{
|
| + break;
|
| + }
|
| + }else if( pPage->nOverflow==0 && pPage->nFree<=nMin ){
|
| + break;
|
| + }else{
|
| + MemPage * const pParent = pCur->apPage[iPage-1];
|
| + int const iIdx = pCur->aiIdx[iPage-1];
|
| +
|
| + rc = sqlite3PagerWrite(pParent->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| +#ifndef SQLITE_OMIT_QUICKBALANCE
|
| + if( pPage->intKeyLeaf
|
| + && pPage->nOverflow==1
|
| + && pPage->aiOvfl[0]==pPage->nCell
|
| + && pParent->pgno!=1
|
| + && pParent->nCell==iIdx
|
| + ){
|
| + /* Call balance_quick() to create a new sibling of pPage on which
|
| + ** to store the overflow cell. balance_quick() inserts a new cell
|
| + ** into pParent, which may cause pParent overflow. If this
|
| + ** happens, the next iteration of the do-loop will balance pParent
|
| + ** use either balance_nonroot() or balance_deeper(). Until this
|
| + ** happens, the overflow cell is stored in the aBalanceQuickSpace[]
|
| + ** buffer.
|
| + **
|
| + ** The purpose of the following assert() is to check that only a
|
| + ** single call to balance_quick() is made for each call to this
|
| + ** function. If this were not verified, a subtle bug involving reuse
|
| + ** of the aBalanceQuickSpace[] might sneak in.
|
| + */
|
| + assert( balance_quick_called==0 );
|
| + VVA_ONLY( balance_quick_called++ );
|
| + rc = balance_quick(pParent, pPage, aBalanceQuickSpace);
|
| + }else
|
| +#endif
|
| + {
|
| + /* In this case, call balance_nonroot() to redistribute cells
|
| + ** between pPage and up to 2 of its sibling pages. This involves
|
| + ** modifying the contents of pParent, which may cause pParent to
|
| + ** become overfull or underfull. The next iteration of the do-loop
|
| + ** will balance the parent page to correct this.
|
| + **
|
| + ** If the parent page becomes overfull, the overflow cell or cells
|
| + ** are stored in the pSpace buffer allocated immediately below.
|
| + ** A subsequent iteration of the do-loop will deal with this by
|
| + ** calling balance_nonroot() (balance_deeper() may be called first,
|
| + ** but it doesn't deal with overflow cells - just moves them to a
|
| + ** different page). Once this subsequent call to balance_nonroot()
|
| + ** has completed, it is safe to release the pSpace buffer used by
|
| + ** the previous call, as the overflow cell data will have been
|
| + ** copied either into the body of a database page or into the new
|
| + ** pSpace buffer passed to the latter call to balance_nonroot().
|
| + */
|
| + u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize);
|
| + rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1,
|
| + pCur->hints&BTREE_BULKLOAD);
|
| + if( pFree ){
|
| + /* If pFree is not NULL, it points to the pSpace buffer used
|
| + ** by a previous call to balance_nonroot(). Its contents are
|
| + ** now stored either on real database pages or within the
|
| + ** new pSpace buffer, so it may be safely freed here. */
|
| + sqlite3PageFree(pFree);
|
| + }
|
| +
|
| + /* The pSpace buffer will be freed after the next call to
|
| + ** balance_nonroot(), or just before this function returns, whichever
|
| + ** comes first. */
|
| + pFree = pSpace;
|
| + }
|
| + }
|
| +
|
| + pPage->nOverflow = 0;
|
| +
|
| + /* The next iteration of the do-loop balances the parent page. */
|
| + releasePage(pPage);
|
| + pCur->iPage--;
|
| + assert( pCur->iPage>=0 );
|
| + }
|
| + }while( rc==SQLITE_OK );
|
| +
|
| + if( pFree ){
|
| + sqlite3PageFree(pFree);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Insert a new record into the BTree. The content of the new record
|
| +** is described by the pX object. The pCur cursor is used only to
|
| +** define what table the record should be inserted into, and is left
|
| +** pointing at a random location.
|
| +**
|
| +** For a table btree (used for rowid tables), only the pX.nKey value of
|
| +** the key is used. The pX.pKey value must be NULL. The pX.nKey is the
|
| +** rowid or INTEGER PRIMARY KEY of the row. The pX.nData,pData,nZero fields
|
| +** hold the content of the row.
|
| +**
|
| +** For an index btree (used for indexes and WITHOUT ROWID tables), the
|
| +** key is an arbitrary byte sequence stored in pX.pKey,nKey. The
|
| +** pX.pData,nData,nZero fields must be zero.
|
| +**
|
| +** If the seekResult parameter is non-zero, then a successful call to
|
| +** MovetoUnpacked() to seek cursor pCur to (pKey,nKey) has already
|
| +** been performed. In other words, if seekResult!=0 then the cursor
|
| +** is currently pointing to a cell that will be adjacent to the cell
|
| +** to be inserted. If seekResult<0 then pCur points to a cell that is
|
| +** smaller then (pKey,nKey). If seekResult>0 then pCur points to a cell
|
| +** that is larger than (pKey,nKey).
|
| +**
|
| +** If seekResult==0, that means pCur is pointing at some unknown location.
|
| +** In that case, this routine must seek the cursor to the correct insertion
|
| +** point for (pKey,nKey) before doing the insertion. For index btrees,
|
| +** if pX->nMem is non-zero, then pX->aMem contains pointers to the unpacked
|
| +** key values and pX->aMem can be used instead of pX->pKey to avoid having
|
| +** to decode the key.
|
| +*/
|
| +int sqlite3BtreeInsert(
|
| + BtCursor *pCur, /* Insert data into the table of this cursor */
|
| + const BtreePayload *pX, /* Content of the row to be inserted */
|
| + int flags, /* True if this is likely an append */
|
| + int seekResult /* Result of prior MovetoUnpacked() call */
|
| +){
|
| + int rc;
|
| + int loc = seekResult; /* -1: before desired location +1: after */
|
| + int szNew = 0;
|
| + int idx;
|
| + MemPage *pPage;
|
| + Btree *p = pCur->pBtree;
|
| + BtShared *pBt = p->pBt;
|
| + unsigned char *oldCell;
|
| + unsigned char *newCell = 0;
|
| +
|
| + assert( (flags & (BTREE_SAVEPOSITION|BTREE_APPEND))==flags );
|
| +
|
| + if( pCur->eState==CURSOR_FAULT ){
|
| + assert( pCur->skipNext!=SQLITE_OK );
|
| + return pCur->skipNext;
|
| + }
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( (pCur->curFlags & BTCF_WriteFlag)!=0
|
| + && pBt->inTransaction==TRANS_WRITE
|
| + && (pBt->btsFlags & BTS_READ_ONLY)==0 );
|
| + assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
|
| +
|
| + /* Assert that the caller has been consistent. If this cursor was opened
|
| + ** expecting an index b-tree, then the caller should be inserting blob
|
| + ** keys with no associated data. If the cursor was opened expecting an
|
| + ** intkey table, the caller should be inserting integer keys with a
|
| + ** blob of associated data. */
|
| + assert( (pX->pKey==0)==(pCur->pKeyInfo==0) );
|
| +
|
| + /* Save the positions of any other cursors open on this table.
|
| + **
|
| + ** In some cases, the call to btreeMoveto() below is a no-op. For
|
| + ** example, when inserting data into a table with auto-generated integer
|
| + ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the
|
| + ** integer key to use. It then calls this function to actually insert the
|
| + ** data into the intkey B-Tree. In this case btreeMoveto() recognizes
|
| + ** that the cursor is already where it needs to be and returns without
|
| + ** doing any work. To avoid thwarting these optimizations, it is important
|
| + ** not to clear the cursor here.
|
| + */
|
| + if( pCur->curFlags & BTCF_Multiple ){
|
| + rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + if( pCur->pKeyInfo==0 ){
|
| + assert( pX->pKey==0 );
|
| + /* If this is an insert into a table b-tree, invalidate any incrblob
|
| + ** cursors open on the row being replaced */
|
| + invalidateIncrblobCursors(p, pX->nKey, 0);
|
| +
|
| + /* If BTREE_SAVEPOSITION is set, the cursor must already be pointing
|
| + ** to a row with the same key as the new entry being inserted. */
|
| + assert( (flags & BTREE_SAVEPOSITION)==0 ||
|
| + ((pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey==pCur->info.nKey) );
|
| +
|
| + /* If the cursor is currently on the last row and we are appending a
|
| + ** new row onto the end, set the "loc" to avoid an unnecessary
|
| + ** btreeMoveto() call */
|
| + if( (pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey==pCur->info.nKey ){
|
| + loc = 0;
|
| + }else if( (pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey>0
|
| + && pCur->info.nKey==pX->nKey-1 ){
|
| + loc = -1;
|
| + }else if( loc==0 ){
|
| + rc = sqlite3BtreeMovetoUnpacked(pCur, 0, pX->nKey, flags!=0, &loc);
|
| + if( rc ) return rc;
|
| + }
|
| + }else if( loc==0 && (flags & BTREE_SAVEPOSITION)==0 ){
|
| + if( pX->nMem ){
|
| + UnpackedRecord r;
|
| + r.pKeyInfo = pCur->pKeyInfo;
|
| + r.aMem = pX->aMem;
|
| + r.nField = pX->nMem;
|
| + r.default_rc = 0;
|
| + r.errCode = 0;
|
| + r.r1 = 0;
|
| + r.r2 = 0;
|
| + r.eqSeen = 0;
|
| + rc = sqlite3BtreeMovetoUnpacked(pCur, &r, 0, flags!=0, &loc);
|
| + }else{
|
| + rc = btreeMoveto(pCur, pX->pKey, pX->nKey, flags!=0, &loc);
|
| + }
|
| + if( rc ) return rc;
|
| + }
|
| + assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );
|
| +
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + assert( pPage->intKey || pX->nKey>=0 );
|
| + assert( pPage->leaf || !pPage->intKey );
|
| +
|
| + TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
|
| + pCur->pgnoRoot, pX->nKey, pX->nData, pPage->pgno,
|
| + loc==0 ? "overwrite" : "new entry"));
|
| + assert( pPage->isInit );
|
| + newCell = pBt->pTmpSpace;
|
| + assert( newCell!=0 );
|
| + rc = fillInCell(pPage, newCell, pX, &szNew);
|
| + if( rc ) goto end_insert;
|
| + assert( szNew==pPage->xCellSize(pPage, newCell) );
|
| + assert( szNew <= MX_CELL_SIZE(pBt) );
|
| + idx = pCur->aiIdx[pCur->iPage];
|
| + if( loc==0 ){
|
| + CellInfo info;
|
| + assert( idx<pPage->nCell );
|
| + rc = sqlite3PagerWrite(pPage->pDbPage);
|
| + if( rc ){
|
| + goto end_insert;
|
| + }
|
| + oldCell = findCell(pPage, idx);
|
| + if( !pPage->leaf ){
|
| + memcpy(newCell, oldCell, 4);
|
| + }
|
| + rc = clearCell(pPage, oldCell, &info);
|
| + if( info.nSize==szNew && info.nLocal==info.nPayload ){
|
| + /* Overwrite the old cell with the new if they are the same size.
|
| + ** We could also try to do this if the old cell is smaller, then add
|
| + ** the leftover space to the free list. But experiments show that
|
| + ** doing that is no faster then skipping this optimization and just
|
| + ** calling dropCell() and insertCell(). */
|
| + assert( rc==SQLITE_OK ); /* clearCell never fails when nLocal==nPayload */
|
| + if( oldCell+szNew > pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
|
| + memcpy(oldCell, newCell, szNew);
|
| + return SQLITE_OK;
|
| + }
|
| + dropCell(pPage, idx, info.nSize, &rc);
|
| + if( rc ) goto end_insert;
|
| + }else if( loc<0 && pPage->nCell>0 ){
|
| + assert( pPage->leaf );
|
| + idx = ++pCur->aiIdx[pCur->iPage];
|
| + }else{
|
| + assert( pPage->leaf );
|
| + }
|
| + insertCell(pPage, idx, newCell, szNew, 0, 0, &rc);
|
| + assert( pPage->nOverflow==0 || rc==SQLITE_OK );
|
| + assert( rc!=SQLITE_OK || pPage->nCell>0 || pPage->nOverflow>0 );
|
| +
|
| + /* If no error has occurred and pPage has an overflow cell, call balance()
|
| + ** to redistribute the cells within the tree. Since balance() may move
|
| + ** the cursor, zero the BtCursor.info.nSize and BTCF_ValidNKey
|
| + ** variables.
|
| + **
|
| + ** Previous versions of SQLite called moveToRoot() to move the cursor
|
| + ** back to the root page as balance() used to invalidate the contents
|
| + ** of BtCursor.apPage[] and BtCursor.aiIdx[]. Instead of doing that,
|
| + ** set the cursor state to "invalid". This makes common insert operations
|
| + ** slightly faster.
|
| + **
|
| + ** There is a subtle but important optimization here too. When inserting
|
| + ** multiple records into an intkey b-tree using a single cursor (as can
|
| + ** happen while processing an "INSERT INTO ... SELECT" statement), it
|
| + ** is advantageous to leave the cursor pointing to the last entry in
|
| + ** the b-tree if possible. If the cursor is left pointing to the last
|
| + ** entry in the table, and the next row inserted has an integer key
|
| + ** larger than the largest existing key, it is possible to insert the
|
| + ** row without seeking the cursor. This can be a big performance boost.
|
| + */
|
| + pCur->info.nSize = 0;
|
| + if( pPage->nOverflow ){
|
| + assert( rc==SQLITE_OK );
|
| + pCur->curFlags &= ~(BTCF_ValidNKey);
|
| + rc = balance(pCur);
|
| +
|
| + /* Must make sure nOverflow is reset to zero even if the balance()
|
| + ** fails. Internal data structure corruption will result otherwise.
|
| + ** Also, set the cursor state to invalid. This stops saveCursorPosition()
|
| + ** from trying to save the current position of the cursor. */
|
| + pCur->apPage[pCur->iPage]->nOverflow = 0;
|
| + pCur->eState = CURSOR_INVALID;
|
| + if( (flags & BTREE_SAVEPOSITION) && rc==SQLITE_OK ){
|
| + rc = moveToRoot(pCur);
|
| + if( pCur->pKeyInfo ){
|
| + assert( pCur->pKey==0 );
|
| + pCur->pKey = sqlite3Malloc( pX->nKey );
|
| + if( pCur->pKey==0 ){
|
| + rc = SQLITE_NOMEM;
|
| + }else{
|
| + memcpy(pCur->pKey, pX->pKey, pX->nKey);
|
| + }
|
| + }
|
| + pCur->eState = CURSOR_REQUIRESEEK;
|
| + pCur->nKey = pX->nKey;
|
| + }
|
| + }
|
| + assert( pCur->apPage[pCur->iPage]->nOverflow==0 );
|
| +
|
| +end_insert:
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Delete the entry that the cursor is pointing to.
|
| +**
|
| +** If the BTREE_SAVEPOSITION bit of the flags parameter is zero, then
|
| +** the cursor is left pointing at an arbitrary location after the delete.
|
| +** But if that bit is set, then the cursor is left in a state such that
|
| +** the next call to BtreeNext() or BtreePrev() moves it to the same row
|
| +** as it would have been on if the call to BtreeDelete() had been omitted.
|
| +**
|
| +** The BTREE_AUXDELETE bit of flags indicates that is one of several deletes
|
| +** associated with a single table entry and its indexes. Only one of those
|
| +** deletes is considered the "primary" delete. The primary delete occurs
|
| +** on a cursor that is not a BTREE_FORDELETE cursor. All but one delete
|
| +** operation on non-FORDELETE cursors is tagged with the AUXDELETE flag.
|
| +** The BTREE_AUXDELETE bit is a hint that is not used by this implementation,
|
| +** but which might be used by alternative storage engines.
|
| +*/
|
| +int sqlite3BtreeDelete(BtCursor *pCur, u8 flags){
|
| + Btree *p = pCur->pBtree;
|
| + BtShared *pBt = p->pBt;
|
| + int rc; /* Return code */
|
| + MemPage *pPage; /* Page to delete cell from */
|
| + unsigned char *pCell; /* Pointer to cell to delete */
|
| + int iCellIdx; /* Index of cell to delete */
|
| + int iCellDepth; /* Depth of node containing pCell */
|
| + CellInfo info; /* Size of the cell being deleted */
|
| + int bSkipnext = 0; /* Leaf cursor in SKIPNEXT state */
|
| + u8 bPreserve = flags & BTREE_SAVEPOSITION; /* Keep cursor valid */
|
| +
|
| + assert( cursorOwnsBtShared(pCur) );
|
| + assert( pBt->inTransaction==TRANS_WRITE );
|
| + assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
|
| + assert( pCur->curFlags & BTCF_WriteFlag );
|
| + assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
|
| + assert( !hasReadConflicts(p, pCur->pgnoRoot) );
|
| + assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
|
| + assert( pCur->eState==CURSOR_VALID );
|
| + assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 );
|
| +
|
| + iCellDepth = pCur->iPage;
|
| + iCellIdx = pCur->aiIdx[iCellDepth];
|
| + pPage = pCur->apPage[iCellDepth];
|
| + pCell = findCell(pPage, iCellIdx);
|
| +
|
| + /* If the bPreserve flag is set to true, then the cursor position must
|
| + ** be preserved following this delete operation. If the current delete
|
| + ** will cause a b-tree rebalance, then this is done by saving the cursor
|
| + ** key and leaving the cursor in CURSOR_REQUIRESEEK state before
|
| + ** returning.
|
| + **
|
| + ** Or, if the current delete will not cause a rebalance, then the cursor
|
| + ** will be left in CURSOR_SKIPNEXT state pointing to the entry immediately
|
| + ** before or after the deleted entry. In this case set bSkipnext to true. */
|
| + if( bPreserve ){
|
| + if( !pPage->leaf
|
| + || (pPage->nFree+cellSizePtr(pPage,pCell)+2)>(int)(pBt->usableSize*2/3)
|
| + ){
|
| + /* A b-tree rebalance will be required after deleting this entry.
|
| + ** Save the cursor key. */
|
| + rc = saveCursorKey(pCur);
|
| + if( rc ) return rc;
|
| + }else{
|
| + bSkipnext = 1;
|
| + }
|
| + }
|
| +
|
| + /* If the page containing the entry to delete is not a leaf page, move
|
| + ** the cursor to the largest entry in the tree that is smaller than
|
| + ** the entry being deleted. This cell will replace the cell being deleted
|
| + ** from the internal node. The 'previous' entry is used for this instead
|
| + ** of the 'next' entry, as the previous entry is always a part of the
|
| + ** sub-tree headed by the child page of the cell being deleted. This makes
|
| + ** balancing the tree following the delete operation easier. */
|
| + if( !pPage->leaf ){
|
| + int notUsed = 0;
|
| + rc = sqlite3BtreePrevious(pCur, ¬Used);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + /* Save the positions of any other cursors open on this table before
|
| + ** making any modifications. */
|
| + if( pCur->curFlags & BTCF_Multiple ){
|
| + rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + /* If this is a delete operation to remove a row from a table b-tree,
|
| + ** invalidate any incrblob cursors open on the row being deleted. */
|
| + if( pCur->pKeyInfo==0 ){
|
| + invalidateIncrblobCursors(p, pCur->info.nKey, 0);
|
| + }
|
| +
|
| + /* Make the page containing the entry to be deleted writable. Then free any
|
| + ** overflow pages associated with the entry and finally remove the cell
|
| + ** itself from within the page. */
|
| + rc = sqlite3PagerWrite(pPage->pDbPage);
|
| + if( rc ) return rc;
|
| + rc = clearCell(pPage, pCell, &info);
|
| + dropCell(pPage, iCellIdx, info.nSize, &rc);
|
| + if( rc ) return rc;
|
| +
|
| + /* If the cell deleted was not located on a leaf page, then the cursor
|
| + ** is currently pointing to the largest entry in the sub-tree headed
|
| + ** by the child-page of the cell that was just deleted from an internal
|
| + ** node. The cell from the leaf node needs to be moved to the internal
|
| + ** node to replace the deleted cell. */
|
| + if( !pPage->leaf ){
|
| + MemPage *pLeaf = pCur->apPage[pCur->iPage];
|
| + int nCell;
|
| + Pgno n = pCur->apPage[iCellDepth+1]->pgno;
|
| + unsigned char *pTmp;
|
| +
|
| + pCell = findCell(pLeaf, pLeaf->nCell-1);
|
| + if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT;
|
| + nCell = pLeaf->xCellSize(pLeaf, pCell);
|
| + assert( MX_CELL_SIZE(pBt) >= nCell );
|
| + pTmp = pBt->pTmpSpace;
|
| + assert( pTmp!=0 );
|
| + rc = sqlite3PagerWrite(pLeaf->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
|
| + }
|
| + dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + /* Balance the tree. If the entry deleted was located on a leaf page,
|
| + ** then the cursor still points to that page. In this case the first
|
| + ** call to balance() repairs the tree, and the if(...) condition is
|
| + ** never true.
|
| + **
|
| + ** Otherwise, if the entry deleted was on an internal node page, then
|
| + ** pCur is pointing to the leaf page from which a cell was removed to
|
| + ** replace the cell deleted from the internal node. This is slightly
|
| + ** tricky as the leaf node may be underfull, and the internal node may
|
| + ** be either under or overfull. In this case run the balancing algorithm
|
| + ** on the leaf node first. If the balance proceeds far enough up the
|
| + ** tree that we can be sure that any problem in the internal node has
|
| + ** been corrected, so be it. Otherwise, after balancing the leaf node,
|
| + ** walk the cursor up the tree to the internal node and balance it as
|
| + ** well. */
|
| + rc = balance(pCur);
|
| + if( rc==SQLITE_OK && pCur->iPage>iCellDepth ){
|
| + while( pCur->iPage>iCellDepth ){
|
| + releasePage(pCur->apPage[pCur->iPage--]);
|
| + }
|
| + rc = balance(pCur);
|
| + }
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + if( bSkipnext ){
|
| + assert( bPreserve && (pCur->iPage==iCellDepth || CORRUPT_DB) );
|
| + assert( pPage==pCur->apPage[pCur->iPage] || CORRUPT_DB );
|
| + assert( (pPage->nCell>0 || CORRUPT_DB) && iCellIdx<=pPage->nCell );
|
| + pCur->eState = CURSOR_SKIPNEXT;
|
| + if( iCellIdx>=pPage->nCell ){
|
| + pCur->skipNext = -1;
|
| + pCur->aiIdx[iCellDepth] = pPage->nCell-1;
|
| + }else{
|
| + pCur->skipNext = 1;
|
| + }
|
| + }else{
|
| + rc = moveToRoot(pCur);
|
| + if( bPreserve ){
|
| + pCur->eState = CURSOR_REQUIRESEEK;
|
| + }
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Create a new BTree table. Write into *piTable the page
|
| +** number for the root page of the new table.
|
| +**
|
| +** The type of type is determined by the flags parameter. Only the
|
| +** following values of flags are currently in use. Other values for
|
| +** flags might not work:
|
| +**
|
| +** BTREE_INTKEY|BTREE_LEAFDATA Used for SQL tables with rowid keys
|
| +** BTREE_ZERODATA Used for SQL indices
|
| +*/
|
| +static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
|
| + BtShared *pBt = p->pBt;
|
| + MemPage *pRoot;
|
| + Pgno pgnoRoot;
|
| + int rc;
|
| + int ptfFlags; /* Page-type flage for the root page of new table */
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( pBt->inTransaction==TRANS_WRITE );
|
| + assert( (pBt->btsFlags & BTS_READ_ONLY)==0 );
|
| +
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
|
| + if( rc ){
|
| + return rc;
|
| + }
|
| +#else
|
| + if( pBt->autoVacuum ){
|
| + Pgno pgnoMove; /* Move a page here to make room for the root-page */
|
| + MemPage *pPageMove; /* The page to move to. */
|
| +
|
| + /* Creating a new table may probably require moving an existing database
|
| + ** to make room for the new tables root page. In case this page turns
|
| + ** out to be an overflow page, delete all overflow page-map caches
|
| + ** held by open cursors.
|
| + */
|
| + invalidateAllOverflowCache(pBt);
|
| +
|
| + /* Read the value of meta[3] from the database to determine where the
|
| + ** root page of the new table should go. meta[3] is the largest root-page
|
| + ** created so far, so the new root-page is (meta[3]+1).
|
| + */
|
| + sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot);
|
| + pgnoRoot++;
|
| +
|
| + /* The new root-page may not be allocated on a pointer-map page, or the
|
| + ** PENDING_BYTE page.
|
| + */
|
| + while( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
|
| + pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
|
| + pgnoRoot++;
|
| + }
|
| + assert( pgnoRoot>=3 || CORRUPT_DB );
|
| + testcase( pgnoRoot<3 );
|
| +
|
| + /* Allocate a page. The page that currently resides at pgnoRoot will
|
| + ** be moved to the allocated page (unless the allocated page happens
|
| + ** to reside at pgnoRoot).
|
| + */
|
| + rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, BTALLOC_EXACT);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| +
|
| + if( pgnoMove!=pgnoRoot ){
|
| + /* pgnoRoot is the page that will be used for the root-page of
|
| + ** the new table (assuming an error did not occur). But we were
|
| + ** allocated pgnoMove. If required (i.e. if it was not allocated
|
| + ** by extending the file), the current page at position pgnoMove
|
| + ** is already journaled.
|
| + */
|
| + u8 eType = 0;
|
| + Pgno iPtrPage = 0;
|
| +
|
| + /* Save the positions of any open cursors. This is required in
|
| + ** case they are holding a reference to an xFetch reference
|
| + ** corresponding to page pgnoRoot. */
|
| + rc = saveAllCursors(pBt, 0, 0);
|
| + releasePage(pPageMove);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| +
|
| + /* Move the page currently at pgnoRoot to pgnoMove. */
|
| + rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
|
| + if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + }
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(pRoot);
|
| + return rc;
|
| + }
|
| + assert( eType!=PTRMAP_ROOTPAGE );
|
| + assert( eType!=PTRMAP_FREEPAGE );
|
| + rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
|
| + releasePage(pRoot);
|
| +
|
| + /* Obtain the page at pgnoRoot */
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + rc = sqlite3PagerWrite(pRoot->pDbPage);
|
| + if( rc!=SQLITE_OK ){
|
| + releasePage(pRoot);
|
| + return rc;
|
| + }
|
| + }else{
|
| + pRoot = pPageMove;
|
| + }
|
| +
|
| + /* Update the pointer-map and meta-data with the new root-page number. */
|
| + ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc);
|
| + if( rc ){
|
| + releasePage(pRoot);
|
| + return rc;
|
| + }
|
| +
|
| + /* When the new root page was allocated, page 1 was made writable in
|
| + ** order either to increase the database filesize, or to decrement the
|
| + ** freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
|
| + */
|
| + assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) );
|
| + rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
|
| + if( NEVER(rc) ){
|
| + releasePage(pRoot);
|
| + return rc;
|
| + }
|
| +
|
| + }else{
|
| + rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
|
| + if( rc ) return rc;
|
| + }
|
| +#endif
|
| + assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
|
| + if( createTabFlags & BTREE_INTKEY ){
|
| + ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF;
|
| + }else{
|
| + ptfFlags = PTF_ZERODATA | PTF_LEAF;
|
| + }
|
| + zeroPage(pRoot, ptfFlags);
|
| + sqlite3PagerUnref(pRoot->pDbPage);
|
| + assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 );
|
| + *piTable = (int)pgnoRoot;
|
| + return SQLITE_OK;
|
| +}
|
| +int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
|
| + int rc;
|
| + sqlite3BtreeEnter(p);
|
| + rc = btreeCreateTable(p, piTable, flags);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Erase the given database page and all its children. Return
|
| +** the page to the freelist.
|
| +*/
|
| +static int clearDatabasePage(
|
| + BtShared *pBt, /* The BTree that contains the table */
|
| + Pgno pgno, /* Page number to clear */
|
| + int freePageFlag, /* Deallocate page if true */
|
| + int *pnChange /* Add number of Cells freed to this counter */
|
| +){
|
| + MemPage *pPage;
|
| + int rc;
|
| + unsigned char *pCell;
|
| + int i;
|
| + int hdr;
|
| + CellInfo info;
|
| +
|
| + assert( sqlite3_mutex_held(pBt->mutex) );
|
| + if( pgno>btreePagecount(pBt) ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| + rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
|
| + if( rc ) return rc;
|
| + if( pPage->bBusy ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto cleardatabasepage_out;
|
| + }
|
| + pPage->bBusy = 1;
|
| + hdr = pPage->hdrOffset;
|
| + for(i=0; i<pPage->nCell; i++){
|
| + pCell = findCell(pPage, i);
|
| + if( !pPage->leaf ){
|
| + rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
|
| + if( rc ) goto cleardatabasepage_out;
|
| + }
|
| + rc = clearCell(pPage, pCell, &info);
|
| + if( rc ) goto cleardatabasepage_out;
|
| + }
|
| + if( !pPage->leaf ){
|
| + rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
|
| + if( rc ) goto cleardatabasepage_out;
|
| + }else if( pnChange ){
|
| + assert( pPage->intKey || CORRUPT_DB );
|
| + testcase( !pPage->intKey );
|
| + *pnChange += pPage->nCell;
|
| + }
|
| + if( freePageFlag ){
|
| + freePage(pPage, &rc);
|
| + }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
|
| + zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF);
|
| + }
|
| +
|
| +cleardatabasepage_out:
|
| + pPage->bBusy = 0;
|
| + releasePage(pPage);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Delete all information from a single table in the database. iTable is
|
| +** the page number of the root of the table. After this routine returns,
|
| +** the root page is empty, but still exists.
|
| +**
|
| +** This routine will fail with SQLITE_LOCKED if there are any open
|
| +** read cursors on the table. Open write cursors are moved to the
|
| +** root of the table.
|
| +**
|
| +** If pnChange is not NULL, then table iTable must be an intkey table. The
|
| +** integer value pointed to by pnChange is incremented by the number of
|
| +** entries in the table.
|
| +*/
|
| +int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
|
| + int rc;
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3BtreeEnter(p);
|
| + assert( p->inTrans==TRANS_WRITE );
|
| +
|
| + rc = saveAllCursors(pBt, (Pgno)iTable, 0);
|
| +
|
| + if( SQLITE_OK==rc ){
|
| + /* Invalidate all incrblob cursors open on table iTable (assuming iTable
|
| + ** is the root of a table b-tree - if it is not, the following call is
|
| + ** a no-op). */
|
| + invalidateIncrblobCursors(p, 0, 1);
|
| + rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Delete all information from the single table that pCur is open on.
|
| +**
|
| +** This routine only work for pCur on an ephemeral table.
|
| +*/
|
| +int sqlite3BtreeClearTableOfCursor(BtCursor *pCur){
|
| + return sqlite3BtreeClearTable(pCur->pBtree, pCur->pgnoRoot, 0);
|
| +}
|
| +
|
| +/*
|
| +** Erase all information in a table and add the root of the table to
|
| +** the freelist. Except, the root of the principle table (the one on
|
| +** page 1) is never added to the freelist.
|
| +**
|
| +** This routine will fail with SQLITE_LOCKED if there are any open
|
| +** cursors on the table.
|
| +**
|
| +** If AUTOVACUUM is enabled and the page at iTable is not the last
|
| +** root page in the database file, then the last root page
|
| +** in the database file is moved into the slot formerly occupied by
|
| +** iTable and that last slot formerly occupied by the last root page
|
| +** is added to the freelist instead of iTable. In this say, all
|
| +** root pages are kept at the beginning of the database file, which
|
| +** is necessary for AUTOVACUUM to work right. *piMoved is set to the
|
| +** page number that used to be the last root page in the file before
|
| +** the move. If no page gets moved, *piMoved is set to 0.
|
| +** The last root page is recorded in meta[3] and the value of
|
| +** meta[3] is updated by this procedure.
|
| +*/
|
| +static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
|
| + int rc;
|
| + MemPage *pPage = 0;
|
| + BtShared *pBt = p->pBt;
|
| +
|
| + assert( sqlite3BtreeHoldsMutex(p) );
|
| + assert( p->inTrans==TRANS_WRITE );
|
| + assert( iTable>=2 );
|
| +
|
| + rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
|
| + if( rc ) return rc;
|
| + rc = sqlite3BtreeClearTable(p, iTable, 0);
|
| + if( rc ){
|
| + releasePage(pPage);
|
| + return rc;
|
| + }
|
| +
|
| + *piMoved = 0;
|
| +
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + freePage(pPage, &rc);
|
| + releasePage(pPage);
|
| +#else
|
| + if( pBt->autoVacuum ){
|
| + Pgno maxRootPgno;
|
| + sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &maxRootPgno);
|
| +
|
| + if( iTable==maxRootPgno ){
|
| + /* If the table being dropped is the table with the largest root-page
|
| + ** number in the database, put the root page on the free list.
|
| + */
|
| + freePage(pPage, &rc);
|
| + releasePage(pPage);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + }else{
|
| + /* The table being dropped does not have the largest root-page
|
| + ** number in the database. So move the page that does into the
|
| + ** gap left by the deleted root-page.
|
| + */
|
| + MemPage *pMove;
|
| + releasePage(pPage);
|
| + rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0);
|
| + releasePage(pMove);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + pMove = 0;
|
| + rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
|
| + freePage(pMove, &rc);
|
| + releasePage(pMove);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + *piMoved = maxRootPgno;
|
| + }
|
| +
|
| + /* Set the new 'max-root-page' value in the database header. This
|
| + ** is the old value less one, less one more if that happens to
|
| + ** be a root-page number, less one again if that is the
|
| + ** PENDING_BYTE_PAGE.
|
| + */
|
| + maxRootPgno--;
|
| + while( maxRootPgno==PENDING_BYTE_PAGE(pBt)
|
| + || PTRMAP_ISPAGE(pBt, maxRootPgno) ){
|
| + maxRootPgno--;
|
| + }
|
| + assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
|
| +
|
| + rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
|
| + }else{
|
| + freePage(pPage, &rc);
|
| + releasePage(pPage);
|
| + }
|
| +#endif
|
| + return rc;
|
| +}
|
| +int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
|
| + int rc;
|
| + sqlite3BtreeEnter(p);
|
| + rc = btreeDropTable(p, iTable, piMoved);
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** This function may only be called if the b-tree connection already
|
| +** has a read or write transaction open on the database.
|
| +**
|
| +** Read the meta-information out of a database file. Meta[0]
|
| +** is the number of free pages currently in the database. Meta[1]
|
| +** through meta[15] are available for use by higher layers. Meta[0]
|
| +** is read-only, the others are read/write.
|
| +**
|
| +** The schema layer numbers meta values differently. At the schema
|
| +** layer (and the SetCookie and ReadCookie opcodes) the number of
|
| +** free pages is not visible. So Cookie[0] is the same as Meta[1].
|
| +**
|
| +** This routine treats Meta[BTREE_DATA_VERSION] as a special case. Instead
|
| +** of reading the value out of the header, it instead loads the "DataVersion"
|
| +** from the pager. The BTREE_DATA_VERSION value is not actually stored in the
|
| +** database file. It is a number computed by the pager. But its access
|
| +** pattern is the same as header meta values, and so it is convenient to
|
| +** read it from this routine.
|
| +*/
|
| +void sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
|
| + BtShared *pBt = p->pBt;
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + assert( p->inTrans>TRANS_NONE );
|
| + assert( SQLITE_OK==querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK) );
|
| + assert( pBt->pPage1 );
|
| + assert( idx>=0 && idx<=15 );
|
| +
|
| + if( idx==BTREE_DATA_VERSION ){
|
| + *pMeta = sqlite3PagerDataVersion(pBt->pPager) + p->iDataVersion;
|
| + }else{
|
| + *pMeta = get4byte(&pBt->pPage1->aData[36 + idx*4]);
|
| + }
|
| +
|
| + /* If auto-vacuum is disabled in this build and this is an auto-vacuum
|
| + ** database, mark the database as read-only. */
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + if( idx==BTREE_LARGEST_ROOT_PAGE && *pMeta>0 ){
|
| + pBt->btsFlags |= BTS_READ_ONLY;
|
| + }
|
| +#endif
|
| +
|
| + sqlite3BtreeLeave(p);
|
| +}
|
| +
|
| +/*
|
| +** Write meta-information back into the database. Meta[0] is
|
| +** read-only and may not be written.
|
| +*/
|
| +int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
|
| + BtShared *pBt = p->pBt;
|
| + unsigned char *pP1;
|
| + int rc;
|
| + assert( idx>=1 && idx<=15 );
|
| + sqlite3BtreeEnter(p);
|
| + assert( p->inTrans==TRANS_WRITE );
|
| + assert( pBt->pPage1!=0 );
|
| + pP1 = pBt->pPage1->aData;
|
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + put4byte(&pP1[36 + idx*4], iMeta);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( idx==BTREE_INCR_VACUUM ){
|
| + assert( pBt->autoVacuum || iMeta==0 );
|
| + assert( iMeta==0 || iMeta==1 );
|
| + pBt->incrVacuum = (u8)iMeta;
|
| + }
|
| +#endif
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_BTREECOUNT
|
| +/*
|
| +** The first argument, pCur, is a cursor opened on some b-tree. Count the
|
| +** number of entries in the b-tree and write the result to *pnEntry.
|
| +**
|
| +** SQLITE_OK is returned if the operation is successfully executed.
|
| +** Otherwise, if an error is encountered (i.e. an IO error or database
|
| +** corruption) an SQLite error code is returned.
|
| +*/
|
| +int sqlite3BtreeCount(BtCursor *pCur, i64 *pnEntry){
|
| + i64 nEntry = 0; /* Value to return in *pnEntry */
|
| + int rc; /* Return code */
|
| +
|
| + if( pCur->pgnoRoot==0 ){
|
| + *pnEntry = 0;
|
| + return SQLITE_OK;
|
| + }
|
| + rc = moveToRoot(pCur);
|
| +
|
| + /* Unless an error occurs, the following loop runs one iteration for each
|
| + ** page in the B-Tree structure (not including overflow pages).
|
| + */
|
| + while( rc==SQLITE_OK ){
|
| + int iIdx; /* Index of child node in parent */
|
| + MemPage *pPage; /* Current page of the b-tree */
|
| +
|
| + /* If this is a leaf page or the tree is not an int-key tree, then
|
| + ** this page contains countable entries. Increment the entry counter
|
| + ** accordingly.
|
| + */
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + if( pPage->leaf || !pPage->intKey ){
|
| + nEntry += pPage->nCell;
|
| + }
|
| +
|
| + /* pPage is a leaf node. This loop navigates the cursor so that it
|
| + ** points to the first interior cell that it points to the parent of
|
| + ** the next page in the tree that has not yet been visited. The
|
| + ** pCur->aiIdx[pCur->iPage] value is set to the index of the parent cell
|
| + ** of the page, or to the number of cells in the page if the next page
|
| + ** to visit is the right-child of its parent.
|
| + **
|
| + ** If all pages in the tree have been visited, return SQLITE_OK to the
|
| + ** caller.
|
| + */
|
| + if( pPage->leaf ){
|
| + do {
|
| + if( pCur->iPage==0 ){
|
| + /* All pages of the b-tree have been visited. Return successfully. */
|
| + *pnEntry = nEntry;
|
| + return moveToRoot(pCur);
|
| + }
|
| + moveToParent(pCur);
|
| + }while ( pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell );
|
| +
|
| + pCur->aiIdx[pCur->iPage]++;
|
| + pPage = pCur->apPage[pCur->iPage];
|
| + }
|
| +
|
| + /* Descend to the child node of the cell that the cursor currently
|
| + ** points at. This is the right-child if (iIdx==pPage->nCell).
|
| + */
|
| + iIdx = pCur->aiIdx[pCur->iPage];
|
| + if( iIdx==pPage->nCell ){
|
| + rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
|
| + }else{
|
| + rc = moveToChild(pCur, get4byte(findCell(pPage, iIdx)));
|
| + }
|
| + }
|
| +
|
| + /* An error has occurred. Return an error code. */
|
| + return rc;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Return the pager associated with a BTree. This routine is used for
|
| +** testing and debugging only.
|
| +*/
|
| +Pager *sqlite3BtreePager(Btree *p){
|
| + return p->pBt->pPager;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_INTEGRITY_CHECK
|
| +/*
|
| +** Append a message to the error message string.
|
| +*/
|
| +static void checkAppendMsg(
|
| + IntegrityCk *pCheck,
|
| + const char *zFormat,
|
| + ...
|
| +){
|
| + va_list ap;
|
| + if( !pCheck->mxErr ) return;
|
| + pCheck->mxErr--;
|
| + pCheck->nErr++;
|
| + va_start(ap, zFormat);
|
| + if( pCheck->errMsg.nChar ){
|
| + sqlite3StrAccumAppend(&pCheck->errMsg, "\n", 1);
|
| + }
|
| + if( pCheck->zPfx ){
|
| + sqlite3XPrintf(&pCheck->errMsg, pCheck->zPfx, pCheck->v1, pCheck->v2);
|
| + }
|
| + sqlite3VXPrintf(&pCheck->errMsg, zFormat, ap);
|
| + va_end(ap);
|
| + if( pCheck->errMsg.accError==STRACCUM_NOMEM ){
|
| + pCheck->mallocFailed = 1;
|
| + }
|
| +}
|
| +#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
|
| +
|
| +#ifndef SQLITE_OMIT_INTEGRITY_CHECK
|
| +
|
| +/*
|
| +** Return non-zero if the bit in the IntegrityCk.aPgRef[] array that
|
| +** corresponds to page iPg is already set.
|
| +*/
|
| +static int getPageReferenced(IntegrityCk *pCheck, Pgno iPg){
|
| + assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 );
|
| + return (pCheck->aPgRef[iPg/8] & (1 << (iPg & 0x07)));
|
| +}
|
| +
|
| +/*
|
| +** Set the bit in the IntegrityCk.aPgRef[] array that corresponds to page iPg.
|
| +*/
|
| +static void setPageReferenced(IntegrityCk *pCheck, Pgno iPg){
|
| + assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 );
|
| + pCheck->aPgRef[iPg/8] |= (1 << (iPg & 0x07));
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Add 1 to the reference count for page iPage. If this is the second
|
| +** reference to the page, add an error message to pCheck->zErrMsg.
|
| +** Return 1 if there are 2 or more references to the page and 0 if
|
| +** if this is the first reference to the page.
|
| +**
|
| +** Also check that the page number is in bounds.
|
| +*/
|
| +static int checkRef(IntegrityCk *pCheck, Pgno iPage){
|
| + if( iPage==0 ) return 1;
|
| + if( iPage>pCheck->nPage ){
|
| + checkAppendMsg(pCheck, "invalid page number %d", iPage);
|
| + return 1;
|
| + }
|
| + if( getPageReferenced(pCheck, iPage) ){
|
| + checkAppendMsg(pCheck, "2nd reference to page %d", iPage);
|
| + return 1;
|
| + }
|
| + setPageReferenced(pCheck, iPage);
|
| + return 0;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +/*
|
| +** Check that the entry in the pointer-map for page iChild maps to
|
| +** page iParent, pointer type ptrType. If not, append an error message
|
| +** to pCheck.
|
| +*/
|
| +static void checkPtrmap(
|
| + IntegrityCk *pCheck, /* Integrity check context */
|
| + Pgno iChild, /* Child page number */
|
| + u8 eType, /* Expected pointer map type */
|
| + Pgno iParent /* Expected pointer map parent page number */
|
| +){
|
| + int rc;
|
| + u8 ePtrmapType;
|
| + Pgno iPtrmapParent;
|
| +
|
| + rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
|
| + if( rc!=SQLITE_OK ){
|
| + if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ) pCheck->mallocFailed = 1;
|
| + checkAppendMsg(pCheck, "Failed to read ptrmap key=%d", iChild);
|
| + return;
|
| + }
|
| +
|
| + if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
|
| + checkAppendMsg(pCheck,
|
| + "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)",
|
| + iChild, eType, iParent, ePtrmapType, iPtrmapParent);
|
| + }
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Check the integrity of the freelist or of an overflow page list.
|
| +** Verify that the number of pages on the list is N.
|
| +*/
|
| +static void checkList(
|
| + IntegrityCk *pCheck, /* Integrity checking context */
|
| + int isFreeList, /* True for a freelist. False for overflow page list */
|
| + int iPage, /* Page number for first page in the list */
|
| + int N /* Expected number of pages in the list */
|
| +){
|
| + int i;
|
| + int expected = N;
|
| + int iFirst = iPage;
|
| + while( N-- > 0 && pCheck->mxErr ){
|
| + DbPage *pOvflPage;
|
| + unsigned char *pOvflData;
|
| + if( iPage<1 ){
|
| + checkAppendMsg(pCheck,
|
| + "%d of %d pages missing from overflow list starting at %d",
|
| + N+1, expected, iFirst);
|
| + break;
|
| + }
|
| + if( checkRef(pCheck, iPage) ) break;
|
| + if( sqlite3PagerGet(pCheck->pPager, (Pgno)iPage, &pOvflPage, 0) ){
|
| + checkAppendMsg(pCheck, "failed to get page %d", iPage);
|
| + break;
|
| + }
|
| + pOvflData = (unsigned char *)sqlite3PagerGetData(pOvflPage);
|
| + if( isFreeList ){
|
| + int n = get4byte(&pOvflData[4]);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pCheck->pBt->autoVacuum ){
|
| + checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0);
|
| + }
|
| +#endif
|
| + if( n>(int)pCheck->pBt->usableSize/4-2 ){
|
| + checkAppendMsg(pCheck,
|
| + "freelist leaf count too big on page %d", iPage);
|
| + N--;
|
| + }else{
|
| + for(i=0; i<n; i++){
|
| + Pgno iFreePage = get4byte(&pOvflData[8+i*4]);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pCheck->pBt->autoVacuum ){
|
| + checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0);
|
| + }
|
| +#endif
|
| + checkRef(pCheck, iFreePage);
|
| + }
|
| + N -= n;
|
| + }
|
| + }
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + else{
|
| + /* If this database supports auto-vacuum and iPage is not the last
|
| + ** page in this overflow list, check that the pointer-map entry for
|
| + ** the following page matches iPage.
|
| + */
|
| + if( pCheck->pBt->autoVacuum && N>0 ){
|
| + i = get4byte(pOvflData);
|
| + checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage);
|
| + }
|
| + }
|
| +#endif
|
| + iPage = get4byte(pOvflData);
|
| + sqlite3PagerUnref(pOvflPage);
|
| +
|
| + if( isFreeList && N<(iPage!=0) ){
|
| + checkAppendMsg(pCheck, "free-page count in header is too small");
|
| + }
|
| + }
|
| +}
|
| +#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
|
| +
|
| +/*
|
| +** An implementation of a min-heap.
|
| +**
|
| +** aHeap[0] is the number of elements on the heap. aHeap[1] is the
|
| +** root element. The daughter nodes of aHeap[N] are aHeap[N*2]
|
| +** and aHeap[N*2+1].
|
| +**
|
| +** The heap property is this: Every node is less than or equal to both
|
| +** of its daughter nodes. A consequence of the heap property is that the
|
| +** root node aHeap[1] is always the minimum value currently in the heap.
|
| +**
|
| +** The btreeHeapInsert() routine inserts an unsigned 32-bit number onto
|
| +** the heap, preserving the heap property. The btreeHeapPull() routine
|
| +** removes the root element from the heap (the minimum value in the heap)
|
| +** and then moves other nodes around as necessary to preserve the heap
|
| +** property.
|
| +**
|
| +** This heap is used for cell overlap and coverage testing. Each u32
|
| +** entry represents the span of a cell or freeblock on a btree page.
|
| +** The upper 16 bits are the index of the first byte of a range and the
|
| +** lower 16 bits are the index of the last byte of that range.
|
| +*/
|
| +static void btreeHeapInsert(u32 *aHeap, u32 x){
|
| + u32 j, i = ++aHeap[0];
|
| + aHeap[i] = x;
|
| + while( (j = i/2)>0 && aHeap[j]>aHeap[i] ){
|
| + x = aHeap[j];
|
| + aHeap[j] = aHeap[i];
|
| + aHeap[i] = x;
|
| + i = j;
|
| + }
|
| +}
|
| +static int btreeHeapPull(u32 *aHeap, u32 *pOut){
|
| + u32 j, i, x;
|
| + if( (x = aHeap[0])==0 ) return 0;
|
| + *pOut = aHeap[1];
|
| + aHeap[1] = aHeap[x];
|
| + aHeap[x] = 0xffffffff;
|
| + aHeap[0]--;
|
| + i = 1;
|
| + while( (j = i*2)<=aHeap[0] ){
|
| + if( aHeap[j]>aHeap[j+1] ) j++;
|
| + if( aHeap[i]<aHeap[j] ) break;
|
| + x = aHeap[i];
|
| + aHeap[i] = aHeap[j];
|
| + aHeap[j] = x;
|
| + i = j;
|
| + }
|
| + return 1;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_INTEGRITY_CHECK
|
| +/*
|
| +** Do various sanity checks on a single page of a tree. Return
|
| +** the tree depth. Root pages return 0. Parents of root pages
|
| +** return 1, and so forth.
|
| +**
|
| +** These checks are done:
|
| +**
|
| +** 1. Make sure that cells and freeblocks do not overlap
|
| +** but combine to completely cover the page.
|
| +** 2. Make sure integer cell keys are in order.
|
| +** 3. Check the integrity of overflow pages.
|
| +** 4. Recursively call checkTreePage on all children.
|
| +** 5. Verify that the depth of all children is the same.
|
| +*/
|
| +static int checkTreePage(
|
| + IntegrityCk *pCheck, /* Context for the sanity check */
|
| + int iPage, /* Page number of the page to check */
|
| + i64 *piMinKey, /* Write minimum integer primary key here */
|
| + i64 maxKey /* Error if integer primary key greater than this */
|
| +){
|
| + MemPage *pPage = 0; /* The page being analyzed */
|
| + int i; /* Loop counter */
|
| + int rc; /* Result code from subroutine call */
|
| + int depth = -1, d2; /* Depth of a subtree */
|
| + int pgno; /* Page number */
|
| + int nFrag; /* Number of fragmented bytes on the page */
|
| + int hdr; /* Offset to the page header */
|
| + int cellStart; /* Offset to the start of the cell pointer array */
|
| + int nCell; /* Number of cells */
|
| + int doCoverageCheck = 1; /* True if cell coverage checking should be done */
|
| + int keyCanBeEqual = 1; /* True if IPK can be equal to maxKey
|
| + ** False if IPK must be strictly less than maxKey */
|
| + u8 *data; /* Page content */
|
| + u8 *pCell; /* Cell content */
|
| + u8 *pCellIdx; /* Next element of the cell pointer array */
|
| + BtShared *pBt; /* The BtShared object that owns pPage */
|
| + u32 pc; /* Address of a cell */
|
| + u32 usableSize; /* Usable size of the page */
|
| + u32 contentOffset; /* Offset to the start of the cell content area */
|
| + u32 *heap = 0; /* Min-heap used for checking cell coverage */
|
| + u32 x, prev = 0; /* Next and previous entry on the min-heap */
|
| + const char *saved_zPfx = pCheck->zPfx;
|
| + int saved_v1 = pCheck->v1;
|
| + int saved_v2 = pCheck->v2;
|
| + u8 savedIsInit = 0;
|
| +
|
| + /* Check that the page exists
|
| + */
|
| + pBt = pCheck->pBt;
|
| + usableSize = pBt->usableSize;
|
| + if( iPage==0 ) return 0;
|
| + if( checkRef(pCheck, iPage) ) return 0;
|
| + pCheck->zPfx = "Page %d: ";
|
| + pCheck->v1 = iPage;
|
| + if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
|
| + checkAppendMsg(pCheck,
|
| + "unable to get the page. error code=%d", rc);
|
| + goto end_of_check;
|
| + }
|
| +
|
| + /* Clear MemPage.isInit to make sure the corruption detection code in
|
| + ** btreeInitPage() is executed. */
|
| + savedIsInit = pPage->isInit;
|
| + pPage->isInit = 0;
|
| + if( (rc = btreeInitPage(pPage))!=0 ){
|
| + assert( rc==SQLITE_CORRUPT ); /* The only possible error from InitPage */
|
| + checkAppendMsg(pCheck,
|
| + "btreeInitPage() returns error code %d", rc);
|
| + goto end_of_check;
|
| + }
|
| + data = pPage->aData;
|
| + hdr = pPage->hdrOffset;
|
| +
|
| + /* Set up for cell analysis */
|
| + pCheck->zPfx = "On tree page %d cell %d: ";
|
| + contentOffset = get2byteNotZero(&data[hdr+5]);
|
| + assert( contentOffset<=usableSize ); /* Enforced by btreeInitPage() */
|
| +
|
| + /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the
|
| + ** number of cells on the page. */
|
| + nCell = get2byte(&data[hdr+3]);
|
| + assert( pPage->nCell==nCell );
|
| +
|
| + /* EVIDENCE-OF: R-23882-45353 The cell pointer array of a b-tree page
|
| + ** immediately follows the b-tree page header. */
|
| + cellStart = hdr + 12 - 4*pPage->leaf;
|
| + assert( pPage->aCellIdx==&data[cellStart] );
|
| + pCellIdx = &data[cellStart + 2*(nCell-1)];
|
| +
|
| + if( !pPage->leaf ){
|
| + /* Analyze the right-child page of internal pages */
|
| + pgno = get4byte(&data[hdr+8]);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum ){
|
| + pCheck->zPfx = "On page %d at right child: ";
|
| + checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage);
|
| + }
|
| +#endif
|
| + depth = checkTreePage(pCheck, pgno, &maxKey, maxKey);
|
| + keyCanBeEqual = 0;
|
| + }else{
|
| + /* For leaf pages, the coverage check will occur in the same loop
|
| + ** as the other cell checks, so initialize the heap. */
|
| + heap = pCheck->heap;
|
| + heap[0] = 0;
|
| + }
|
| +
|
| + /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte
|
| + ** integer offsets to the cell contents. */
|
| + for(i=nCell-1; i>=0 && pCheck->mxErr; i--){
|
| + CellInfo info;
|
| +
|
| + /* Check cell size */
|
| + pCheck->v2 = i;
|
| + assert( pCellIdx==&data[cellStart + i*2] );
|
| + pc = get2byteAligned(pCellIdx);
|
| + pCellIdx -= 2;
|
| + if( pc<contentOffset || pc>usableSize-4 ){
|
| + checkAppendMsg(pCheck, "Offset %d out of range %d..%d",
|
| + pc, contentOffset, usableSize-4);
|
| + doCoverageCheck = 0;
|
| + continue;
|
| + }
|
| + pCell = &data[pc];
|
| + pPage->xParseCell(pPage, pCell, &info);
|
| + if( pc+info.nSize>usableSize ){
|
| + checkAppendMsg(pCheck, "Extends off end of page");
|
| + doCoverageCheck = 0;
|
| + continue;
|
| + }
|
| +
|
| + /* Check for integer primary key out of range */
|
| + if( pPage->intKey ){
|
| + if( keyCanBeEqual ? (info.nKey > maxKey) : (info.nKey >= maxKey) ){
|
| + checkAppendMsg(pCheck, "Rowid %lld out of order", info.nKey);
|
| + }
|
| + maxKey = info.nKey;
|
| + }
|
| +
|
| + /* Check the content overflow list */
|
| + if( info.nPayload>info.nLocal ){
|
| + int nPage; /* Number of pages on the overflow chain */
|
| + Pgno pgnoOvfl; /* First page of the overflow chain */
|
| + assert( pc + info.nSize - 4 <= usableSize );
|
| + nPage = (info.nPayload - info.nLocal + usableSize - 5)/(usableSize - 4);
|
| + pgnoOvfl = get4byte(&pCell[info.nSize - 4]);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum ){
|
| + checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage);
|
| + }
|
| +#endif
|
| + checkList(pCheck, 0, pgnoOvfl, nPage);
|
| + }
|
| +
|
| + if( !pPage->leaf ){
|
| + /* Check sanity of left child page for internal pages */
|
| + pgno = get4byte(pCell);
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum ){
|
| + checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage);
|
| + }
|
| +#endif
|
| + d2 = checkTreePage(pCheck, pgno, &maxKey, maxKey);
|
| + keyCanBeEqual = 0;
|
| + if( d2!=depth ){
|
| + checkAppendMsg(pCheck, "Child page depth differs");
|
| + depth = d2;
|
| + }
|
| + }else{
|
| + /* Populate the coverage-checking heap for leaf pages */
|
| + btreeHeapInsert(heap, (pc<<16)|(pc+info.nSize-1));
|
| + }
|
| + }
|
| + *piMinKey = maxKey;
|
| +
|
| + /* Check for complete coverage of the page
|
| + */
|
| + pCheck->zPfx = 0;
|
| + if( doCoverageCheck && pCheck->mxErr>0 ){
|
| + /* For leaf pages, the min-heap has already been initialized and the
|
| + ** cells have already been inserted. But for internal pages, that has
|
| + ** not yet been done, so do it now */
|
| + if( !pPage->leaf ){
|
| + heap = pCheck->heap;
|
| + heap[0] = 0;
|
| + for(i=nCell-1; i>=0; i--){
|
| + u32 size;
|
| + pc = get2byteAligned(&data[cellStart+i*2]);
|
| + size = pPage->xCellSize(pPage, &data[pc]);
|
| + btreeHeapInsert(heap, (pc<<16)|(pc+size-1));
|
| + }
|
| + }
|
| + /* Add the freeblocks to the min-heap
|
| + **
|
| + ** EVIDENCE-OF: R-20690-50594 The second field of the b-tree page header
|
| + ** is the offset of the first freeblock, or zero if there are no
|
| + ** freeblocks on the page.
|
| + */
|
| + i = get2byte(&data[hdr+1]);
|
| + while( i>0 ){
|
| + int size, j;
|
| + assert( (u32)i<=usableSize-4 ); /* Enforced by btreeInitPage() */
|
| + size = get2byte(&data[i+2]);
|
| + assert( (u32)(i+size)<=usableSize ); /* Enforced by btreeInitPage() */
|
| + btreeHeapInsert(heap, (((u32)i)<<16)|(i+size-1));
|
| + /* EVIDENCE-OF: R-58208-19414 The first 2 bytes of a freeblock are a
|
| + ** big-endian integer which is the offset in the b-tree page of the next
|
| + ** freeblock in the chain, or zero if the freeblock is the last on the
|
| + ** chain. */
|
| + j = get2byte(&data[i]);
|
| + /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
|
| + ** increasing offset. */
|
| + assert( j==0 || j>i+size ); /* Enforced by btreeInitPage() */
|
| + assert( (u32)j<=usableSize-4 ); /* Enforced by btreeInitPage() */
|
| + i = j;
|
| + }
|
| + /* Analyze the min-heap looking for overlap between cells and/or
|
| + ** freeblocks, and counting the number of untracked bytes in nFrag.
|
| + **
|
| + ** Each min-heap entry is of the form: (start_address<<16)|end_address.
|
| + ** There is an implied first entry the covers the page header, the cell
|
| + ** pointer index, and the gap between the cell pointer index and the start
|
| + ** of cell content.
|
| + **
|
| + ** The loop below pulls entries from the min-heap in order and compares
|
| + ** the start_address against the previous end_address. If there is an
|
| + ** overlap, that means bytes are used multiple times. If there is a gap,
|
| + ** that gap is added to the fragmentation count.
|
| + */
|
| + nFrag = 0;
|
| + prev = contentOffset - 1; /* Implied first min-heap entry */
|
| + while( btreeHeapPull(heap,&x) ){
|
| + if( (prev&0xffff)>=(x>>16) ){
|
| + checkAppendMsg(pCheck,
|
| + "Multiple uses for byte %u of page %d", x>>16, iPage);
|
| + break;
|
| + }else{
|
| + nFrag += (x>>16) - (prev&0xffff) - 1;
|
| + prev = x;
|
| + }
|
| + }
|
| + nFrag += usableSize - (prev&0xffff) - 1;
|
| + /* EVIDENCE-OF: R-43263-13491 The total number of bytes in all fragments
|
| + ** is stored in the fifth field of the b-tree page header.
|
| + ** EVIDENCE-OF: R-07161-27322 The one-byte integer at offset 7 gives the
|
| + ** number of fragmented free bytes within the cell content area.
|
| + */
|
| + if( heap[0]==0 && nFrag!=data[hdr+7] ){
|
| + checkAppendMsg(pCheck,
|
| + "Fragmentation of %d bytes reported as %d on page %d",
|
| + nFrag, data[hdr+7], iPage);
|
| + }
|
| + }
|
| +
|
| +end_of_check:
|
| + if( !doCoverageCheck ) pPage->isInit = savedIsInit;
|
| + releasePage(pPage);
|
| + pCheck->zPfx = saved_zPfx;
|
| + pCheck->v1 = saved_v1;
|
| + pCheck->v2 = saved_v2;
|
| + return depth+1;
|
| +}
|
| +#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
|
| +
|
| +#ifndef SQLITE_OMIT_INTEGRITY_CHECK
|
| +/*
|
| +** This routine does a complete check of the given BTree file. aRoot[] is
|
| +** an array of pages numbers were each page number is the root page of
|
| +** a table. nRoot is the number of entries in aRoot.
|
| +**
|
| +** A read-only or read-write transaction must be opened before calling
|
| +** this function.
|
| +**
|
| +** Write the number of error seen in *pnErr. Except for some memory
|
| +** allocation errors, an error message held in memory obtained from
|
| +** malloc is returned if *pnErr is non-zero. If *pnErr==0 then NULL is
|
| +** returned. If a memory allocation error occurs, NULL is returned.
|
| +*/
|
| +char *sqlite3BtreeIntegrityCheck(
|
| + Btree *p, /* The btree to be checked */
|
| + int *aRoot, /* An array of root pages numbers for individual trees */
|
| + int nRoot, /* Number of entries in aRoot[] */
|
| + int mxErr, /* Stop reporting errors after this many */
|
| + int *pnErr /* Write number of errors seen to this variable */
|
| +){
|
| + Pgno i;
|
| + IntegrityCk sCheck;
|
| + BtShared *pBt = p->pBt;
|
| + int savedDbFlags = pBt->db->flags;
|
| + char zErr[100];
|
| + VVA_ONLY( int nRef );
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
|
| + VVA_ONLY( nRef = sqlite3PagerRefcount(pBt->pPager) );
|
| + assert( nRef>=0 );
|
| + sCheck.pBt = pBt;
|
| + sCheck.pPager = pBt->pPager;
|
| + sCheck.nPage = btreePagecount(sCheck.pBt);
|
| + sCheck.mxErr = mxErr;
|
| + sCheck.nErr = 0;
|
| + sCheck.mallocFailed = 0;
|
| + sCheck.zPfx = 0;
|
| + sCheck.v1 = 0;
|
| + sCheck.v2 = 0;
|
| + sCheck.aPgRef = 0;
|
| + sCheck.heap = 0;
|
| + sqlite3StrAccumInit(&sCheck.errMsg, 0, zErr, sizeof(zErr), SQLITE_MAX_LENGTH);
|
| + sCheck.errMsg.printfFlags = SQLITE_PRINTF_INTERNAL;
|
| + if( sCheck.nPage==0 ){
|
| + goto integrity_ck_cleanup;
|
| + }
|
| +
|
| + sCheck.aPgRef = sqlite3MallocZero((sCheck.nPage / 8)+ 1);
|
| + if( !sCheck.aPgRef ){
|
| + sCheck.mallocFailed = 1;
|
| + goto integrity_ck_cleanup;
|
| + }
|
| + sCheck.heap = (u32*)sqlite3PageMalloc( pBt->pageSize );
|
| + if( sCheck.heap==0 ){
|
| + sCheck.mallocFailed = 1;
|
| + goto integrity_ck_cleanup;
|
| + }
|
| +
|
| + i = PENDING_BYTE_PAGE(pBt);
|
| + if( i<=sCheck.nPage ) setPageReferenced(&sCheck, i);
|
| +
|
| + /* Check the integrity of the freelist
|
| + */
|
| + sCheck.zPfx = "Main freelist: ";
|
| + checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
|
| + get4byte(&pBt->pPage1->aData[36]));
|
| + sCheck.zPfx = 0;
|
| +
|
| + /* Check all the tables.
|
| + */
|
| + testcase( pBt->db->flags & SQLITE_CellSizeCk );
|
| + pBt->db->flags &= ~SQLITE_CellSizeCk;
|
| + for(i=0; (int)i<nRoot && sCheck.mxErr; i++){
|
| + i64 notUsed;
|
| + if( aRoot[i]==0 ) continue;
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pBt->autoVacuum && aRoot[i]>1 ){
|
| + checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0);
|
| + }
|
| +#endif
|
| + checkTreePage(&sCheck, aRoot[i], ¬Used, LARGEST_INT64);
|
| + }
|
| + pBt->db->flags = savedDbFlags;
|
| +
|
| + /* Make sure every page in the file is referenced
|
| + */
|
| + for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
|
| +#ifdef SQLITE_OMIT_AUTOVACUUM
|
| + if( getPageReferenced(&sCheck, i)==0 ){
|
| + checkAppendMsg(&sCheck, "Page %d is never used", i);
|
| + }
|
| +#else
|
| + /* If the database supports auto-vacuum, make sure no tables contain
|
| + ** references to pointer-map pages.
|
| + */
|
| + if( getPageReferenced(&sCheck, i)==0 &&
|
| + (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
|
| + checkAppendMsg(&sCheck, "Page %d is never used", i);
|
| + }
|
| + if( getPageReferenced(&sCheck, i)!=0 &&
|
| + (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
|
| + checkAppendMsg(&sCheck, "Pointer map page %d is referenced", i);
|
| + }
|
| +#endif
|
| + }
|
| +
|
| + /* Clean up and report errors.
|
| + */
|
| +integrity_ck_cleanup:
|
| + sqlite3PageFree(sCheck.heap);
|
| + sqlite3_free(sCheck.aPgRef);
|
| + if( sCheck.mallocFailed ){
|
| + sqlite3StrAccumReset(&sCheck.errMsg);
|
| + sCheck.nErr++;
|
| + }
|
| + *pnErr = sCheck.nErr;
|
| + if( sCheck.nErr==0 ) sqlite3StrAccumReset(&sCheck.errMsg);
|
| + /* Make sure this analysis did not leave any unref() pages. */
|
| + assert( nRef==sqlite3PagerRefcount(pBt->pPager) );
|
| + sqlite3BtreeLeave(p);
|
| + return sqlite3StrAccumFinish(&sCheck.errMsg);
|
| +}
|
| +#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
|
| +
|
| +/*
|
| +** Return the full pathname of the underlying database file. Return
|
| +** an empty string if the database is in-memory or a TEMP database.
|
| +**
|
| +** The pager filename is invariant as long as the pager is
|
| +** open so it is safe to access without the BtShared mutex.
|
| +*/
|
| +const char *sqlite3BtreeGetFilename(Btree *p){
|
| + assert( p->pBt->pPager!=0 );
|
| + return sqlite3PagerFilename(p->pBt->pPager, 1);
|
| +}
|
| +
|
| +/*
|
| +** Return the pathname of the journal file for this database. The return
|
| +** value of this routine is the same regardless of whether the journal file
|
| +** has been created or not.
|
| +**
|
| +** The pager journal filename is invariant as long as the pager is
|
| +** open so it is safe to access without the BtShared mutex.
|
| +*/
|
| +const char *sqlite3BtreeGetJournalname(Btree *p){
|
| + assert( p->pBt->pPager!=0 );
|
| + return sqlite3PagerJournalname(p->pBt->pPager);
|
| +}
|
| +
|
| +/*
|
| +** Return non-zero if a transaction is active.
|
| +*/
|
| +int sqlite3BtreeIsInTrans(Btree *p){
|
| + assert( p==0 || sqlite3_mutex_held(p->db->mutex) );
|
| + return (p && (p->inTrans==TRANS_WRITE));
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_WAL
|
| +/*
|
| +** Run a checkpoint on the Btree passed as the first argument.
|
| +**
|
| +** Return SQLITE_LOCKED if this or any other connection has an open
|
| +** transaction on the shared-cache the argument Btree is connected to.
|
| +**
|
| +** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
|
| +*/
|
| +int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){
|
| + int rc = SQLITE_OK;
|
| + if( p ){
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3BtreeEnter(p);
|
| + if( pBt->inTransaction!=TRANS_NONE ){
|
| + rc = SQLITE_LOCKED;
|
| + }else{
|
| + rc = sqlite3PagerCheckpoint(pBt->pPager, p->db, eMode, pnLog, pnCkpt);
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + }
|
| + return rc;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Return non-zero if a read (or write) transaction is active.
|
| +*/
|
| +int sqlite3BtreeIsInReadTrans(Btree *p){
|
| + assert( p );
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + return p->inTrans!=TRANS_NONE;
|
| +}
|
| +
|
| +int sqlite3BtreeIsInBackup(Btree *p){
|
| + assert( p );
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + return p->nBackup!=0;
|
| +}
|
| +
|
| +/*
|
| +** This function returns a pointer to a blob of memory associated with
|
| +** a single shared-btree. The memory is used by client code for its own
|
| +** purposes (for example, to store a high-level schema associated with
|
| +** the shared-btree). The btree layer manages reference counting issues.
|
| +**
|
| +** The first time this is called on a shared-btree, nBytes bytes of memory
|
| +** are allocated, zeroed, and returned to the caller. For each subsequent
|
| +** call the nBytes parameter is ignored and a pointer to the same blob
|
| +** of memory returned.
|
| +**
|
| +** If the nBytes parameter is 0 and the blob of memory has not yet been
|
| +** allocated, a null pointer is returned. If the blob has already been
|
| +** allocated, it is returned as normal.
|
| +**
|
| +** Just before the shared-btree is closed, the function passed as the
|
| +** xFree argument when the memory allocation was made is invoked on the
|
| +** blob of allocated memory. The xFree function should not call sqlite3_free()
|
| +** on the memory, the btree layer does that.
|
| +*/
|
| +void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
|
| + BtShared *pBt = p->pBt;
|
| + sqlite3BtreeEnter(p);
|
| + if( !pBt->pSchema && nBytes ){
|
| + pBt->pSchema = sqlite3DbMallocZero(0, nBytes);
|
| + pBt->xFreeSchema = xFree;
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + return pBt->pSchema;
|
| +}
|
| +
|
| +/*
|
| +** Return SQLITE_LOCKED_SHAREDCACHE if another user of the same shared
|
| +** btree as the argument handle holds an exclusive lock on the
|
| +** sqlite_master table. Otherwise SQLITE_OK.
|
| +*/
|
| +int sqlite3BtreeSchemaLocked(Btree *p){
|
| + int rc;
|
| + assert( sqlite3_mutex_held(p->db->mutex) );
|
| + sqlite3BtreeEnter(p);
|
| + rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
|
| + assert( rc==SQLITE_OK || rc==SQLITE_LOCKED_SHAREDCACHE );
|
| + sqlite3BtreeLeave(p);
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +#ifndef SQLITE_OMIT_SHARED_CACHE
|
| +/*
|
| +** Obtain a lock on the table whose root page is iTab. The
|
| +** lock is a write lock if isWritelock is true or a read lock
|
| +** if it is false.
|
| +*/
|
| +int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
|
| + int rc = SQLITE_OK;
|
| + assert( p->inTrans!=TRANS_NONE );
|
| + if( p->sharable ){
|
| + u8 lockType = READ_LOCK + isWriteLock;
|
| + assert( READ_LOCK+1==WRITE_LOCK );
|
| + assert( isWriteLock==0 || isWriteLock==1 );
|
| +
|
| + sqlite3BtreeEnter(p);
|
| + rc = querySharedCacheTableLock(p, iTab, lockType);
|
| + if( rc==SQLITE_OK ){
|
| + rc = setSharedCacheTableLock(p, iTab, lockType);
|
| + }
|
| + sqlite3BtreeLeave(p);
|
| + }
|
| + return rc;
|
| +}
|
| +#endif
|
| +
|
| +#ifndef SQLITE_OMIT_INCRBLOB
|
| +/*
|
| +** Argument pCsr must be a cursor opened for writing on an
|
| +** INTKEY table currently pointing at a valid table entry.
|
| +** This function modifies the data stored as part of that entry.
|
| +**
|
| +** Only the data content may only be modified, it is not possible to
|
| +** change the length of the data stored. If this function is called with
|
| +** parameters that attempt to write past the end of the existing data,
|
| +** no modifications are made and SQLITE_CORRUPT is returned.
|
| +*/
|
| +int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
|
| + int rc;
|
| + assert( cursorOwnsBtShared(pCsr) );
|
| + assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) );
|
| + assert( pCsr->curFlags & BTCF_Incrblob );
|
| +
|
| + rc = restoreCursorPosition(pCsr);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + assert( pCsr->eState!=CURSOR_REQUIRESEEK );
|
| + if( pCsr->eState!=CURSOR_VALID ){
|
| + return SQLITE_ABORT;
|
| + }
|
| +
|
| + /* Save the positions of all other cursors open on this table. This is
|
| + ** required in case any of them are holding references to an xFetch
|
| + ** version of the b-tree page modified by the accessPayload call below.
|
| + **
|
| + ** Note that pCsr must be open on a INTKEY table and saveCursorPosition()
|
| + ** and hence saveAllCursors() cannot fail on a BTREE_INTKEY table, hence
|
| + ** saveAllCursors can only return SQLITE_OK.
|
| + */
|
| + VVA_ONLY(rc =) saveAllCursors(pCsr->pBt, pCsr->pgnoRoot, pCsr);
|
| + assert( rc==SQLITE_OK );
|
| +
|
| + /* Check some assumptions:
|
| + ** (a) the cursor is open for writing,
|
| + ** (b) there is a read/write transaction open,
|
| + ** (c) the connection holds a write-lock on the table (if required),
|
| + ** (d) there are no conflicting read-locks, and
|
| + ** (e) the cursor points at a valid row of an intKey table.
|
| + */
|
| + if( (pCsr->curFlags & BTCF_WriteFlag)==0 ){
|
| + return SQLITE_READONLY;
|
| + }
|
| + assert( (pCsr->pBt->btsFlags & BTS_READ_ONLY)==0
|
| + && pCsr->pBt->inTransaction==TRANS_WRITE );
|
| + assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) );
|
| + assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) );
|
| + assert( pCsr->apPage[pCsr->iPage]->intKey );
|
| +
|
| + return accessPayload(pCsr, offset, amt, (unsigned char *)z, 1);
|
| +}
|
| +
|
| +/*
|
| +** Mark this cursor as an incremental blob cursor.
|
| +*/
|
| +void sqlite3BtreeIncrblobCursor(BtCursor *pCur){
|
| + pCur->curFlags |= BTCF_Incrblob;
|
| + pCur->pBtree->hasIncrblobCur = 1;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Set both the "read version" (single byte at byte offset 18) and
|
| +** "write version" (single byte at byte offset 19) fields in the database
|
| +** header to iVersion.
|
| +*/
|
| +int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
|
| + BtShared *pBt = pBtree->pBt;
|
| + int rc; /* Return code */
|
| +
|
| + assert( iVersion==1 || iVersion==2 );
|
| +
|
| + /* If setting the version fields to 1, do not automatically open the
|
| + ** WAL connection, even if the version fields are currently set to 2.
|
| + */
|
| + pBt->btsFlags &= ~BTS_NO_WAL;
|
| + if( iVersion==1 ) pBt->btsFlags |= BTS_NO_WAL;
|
| +
|
| + rc = sqlite3BtreeBeginTrans(pBtree, 0);
|
| + if( rc==SQLITE_OK ){
|
| + u8 *aData = pBt->pPage1->aData;
|
| + if( aData[18]!=(u8)iVersion || aData[19]!=(u8)iVersion ){
|
| + rc = sqlite3BtreeBeginTrans(pBtree, 2);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
|
| + if( rc==SQLITE_OK ){
|
| + aData[18] = (u8)iVersion;
|
| + aData[19] = (u8)iVersion;
|
| + }
|
| + }
|
| + }
|
| + }
|
| +
|
| + pBt->btsFlags &= ~BTS_NO_WAL;
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return true if the cursor has a hint specified. This routine is
|
| +** only used from within assert() statements
|
| +*/
|
| +int sqlite3BtreeCursorHasHint(BtCursor *pCsr, unsigned int mask){
|
| + return (pCsr->hints & mask)!=0;
|
| +}
|
| +
|
| +/*
|
| +** Return true if the given Btree is read-only.
|
| +*/
|
| +int sqlite3BtreeIsReadonly(Btree *p){
|
| + return (p->pBt->btsFlags & BTS_READ_ONLY)!=0;
|
| +}
|
| +
|
| +/*
|
| +** Return the size of the header added to each page by this module.
|
| +*/
|
| +int sqlite3HeaderSizeBtree(void){ return ROUND8(sizeof(MemPage)); }
|
| +
|
| +#if !defined(SQLITE_OMIT_SHARED_CACHE)
|
| +/*
|
| +** Return true if the Btree passed as the only argument is sharable.
|
| +*/
|
| +int sqlite3BtreeSharable(Btree *p){
|
| + return p->sharable;
|
| +}
|
| +
|
| +/*
|
| +** Return the number of connections to the BtShared object accessed by
|
| +** the Btree handle passed as the only argument. For private caches
|
| +** this is always 1. For shared caches it may be 1 or greater.
|
| +*/
|
| +int sqlite3BtreeConnectionCount(Btree *p){
|
| + testcase( p->sharable );
|
| + return p->pBt->nRef;
|
| +}
|
| +#endif
|
|
|
Chromium Code Reviews
Issue 2747283002:
[sql] Import reference version of SQLite 3.17.. (Closed)
