[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/src/vdbeblob.c

+/*
+** 2007 May 1
+**
+** 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 contains code used to implement incremental BLOB I/O.
+*/
+
+#include "sqliteInt.h"
+#include "vdbeInt.h"
+
+#ifndef SQLITE_OMIT_INCRBLOB
+
+/*
+** Valid sqlite3_blob* handles point to Incrblob structures.
+*/
+typedef struct Incrblob Incrblob;
+struct Incrblob {
+  int nByte;              /* Size of open blob, in bytes */
+  int iOffset;            /* Byte offset of blob in cursor data */
+  u16 iCol;               /* Table column this handle is open on */
+  BtCursor *pCsr;         /* Cursor pointing at blob row */
+  sqlite3_stmt *pStmt;    /* Statement holding cursor open */
+  sqlite3 *db;            /* The associated database */
+  char *zDb;              /* Database name */
+  Table *pTab;            /* Table object */
+};
+
+
+/*
+** This function is used by both blob_open() and blob_reopen(). It seeks
+** the b-tree cursor associated with blob handle p to point to row iRow.
+** If successful, SQLITE_OK is returned and subsequent calls to
+** sqlite3_blob_read() or sqlite3_blob_write() access the specified row.
+**
+** If an error occurs, or if the specified row does not exist or does not
+** contain a value of type TEXT or BLOB in the column nominated when the
+** blob handle was opened, then an error code is returned and *pzErr may
+** be set to point to a buffer containing an error message. It is the
+** responsibility of the caller to free the error message buffer using
+** sqlite3DbFree().
+**
+** If an error does occur, then the b-tree cursor is closed. All subsequent
+** calls to sqlite3_blob_read(), blob_write() or blob_reopen() will 
+** immediately return SQLITE_ABORT.
+*/
+static int blobSeekToRow(Incrblob *p, sqlite3_int64 iRow, char **pzErr){
+  int rc;                         /* Error code */
+  char *zErr = 0;                 /* Error message */
+  Vdbe *v = (Vdbe *)p->pStmt;
+
+  /* Set the value of register r[1] in the SQL statement to integer iRow. 
+  ** This is done directly as a performance optimization
+  */
+  v->aMem[1].flags = MEM_Int;
+  v->aMem[1].u.i = iRow;
+
+  /* If the statement has been run before (and is paused at the OP_ResultRow)
+  ** then back it up to the point where it does the OP_SeekRowid.  This could
+  ** have been down with an extra OP_Goto, but simply setting the program
+  ** counter is faster. */
+  if( v->pc>3 ){
+    v->pc = 3;
+    rc = sqlite3VdbeExec(v);
+  }else{
+    rc = sqlite3_step(p->pStmt);
+  }
+  if( rc==SQLITE_ROW ){
+    VdbeCursor *pC = v->apCsr[0];
+    u32 type = pC->nHdrParsed>p->iCol ? pC->aType[p->iCol] : 0;
+    testcase( pC->nHdrParsed==p->iCol );
+    testcase( pC->nHdrParsed==p->iCol+1 );
+    if( type<12 ){
+      zErr = sqlite3MPrintf(p->db, "cannot open value of type %s",
+          type==0?"null": type==7?"real": "integer"
+      );
+      rc = SQLITE_ERROR;
+      sqlite3_finalize(p->pStmt);
+      p->pStmt = 0;
+    }else{
+      p->iOffset = pC->aType[p->iCol + pC->nField];
+      p->nByte = sqlite3VdbeSerialTypeLen(type);
+      p->pCsr =  pC->uc.pCursor;
+      sqlite3BtreeIncrblobCursor(p->pCsr);
+    }
+  }
+
+  if( rc==SQLITE_ROW ){
+    rc = SQLITE_OK;
+  }else if( p->pStmt ){
+    rc = sqlite3_finalize(p->pStmt);
+    p->pStmt = 0;
+    if( rc==SQLITE_OK ){
+      zErr = sqlite3MPrintf(p->db, "no such rowid: %lld", iRow);
+      rc = SQLITE_ERROR;
+    }else{
+      zErr = sqlite3MPrintf(p->db, "%s", sqlite3_errmsg(p->db));
+    }
+  }
+
+  assert( rc!=SQLITE_OK || zErr==0 );
+  assert( rc!=SQLITE_ROW && rc!=SQLITE_DONE );
+
+  *pzErr = zErr;
+  return rc;
+}
+
+/*
+** Open a blob handle.
+*/
+int sqlite3_blob_open(
+  sqlite3* db,            /* The database connection */
+  const char *zDb,        /* The attached database containing the blob */
+  const char *zTable,     /* The table containing the blob */
+  const char *zColumn,    /* The column containing the blob */
+  sqlite_int64 iRow,      /* The row containing the glob */
+  int wrFlag,             /* True -> read/write access, false -> read-only */
+  sqlite3_blob **ppBlob   /* Handle for accessing the blob returned here */
+){
+  int nAttempt = 0;
+  int iCol;               /* Index of zColumn in row-record */
+  int rc = SQLITE_OK;
+  char *zErr = 0;
+  Table *pTab;
+  Parse *pParse = 0;
+  Incrblob *pBlob = 0;
+
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( ppBlob==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  *ppBlob = 0;
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( !sqlite3SafetyCheckOk(db) || zTable==0 ){
+    return SQLITE_MISUSE_BKPT;
+  }
+#endif
+  wrFlag = !!wrFlag;                /* wrFlag = (wrFlag ? 1 : 0); */
+
+  sqlite3_mutex_enter(db->mutex);
+
+  pBlob = (Incrblob *)sqlite3DbMallocZero(db, sizeof(Incrblob));
+  if( !pBlob ) goto blob_open_out;
+  pParse = sqlite3StackAllocRaw(db, sizeof(*pParse));
+  if( !pParse ) goto blob_open_out;
+
+  do {
+    memset(pParse, 0, sizeof(Parse));
+    pParse->db = db;
+    sqlite3DbFree(db, zErr);
+    zErr = 0;
+
+    sqlite3BtreeEnterAll(db);
+    pTab = sqlite3LocateTable(pParse, 0, zTable, zDb);
+    if( pTab && IsVirtual(pTab) ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open virtual table: %s", zTable);
+    }
+    if( pTab && !HasRowid(pTab) ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open table without rowid: %s", zTable);
+    }
+#ifndef SQLITE_OMIT_VIEW
+    if( pTab && pTab->pSelect ){
+      pTab = 0;
+      sqlite3ErrorMsg(pParse, "cannot open view: %s", zTable);
+    }
+#endif
+    if( !pTab ){
+      if( pParse->zErrMsg ){
+        sqlite3DbFree(db, zErr);
+        zErr = pParse->zErrMsg;
+        pParse->zErrMsg = 0;
+      }
+      rc = SQLITE_ERROR;
+      sqlite3BtreeLeaveAll(db);
+      goto blob_open_out;
+    }
+    pBlob->pTab = pTab;
+    pBlob->zDb = db->aDb[sqlite3SchemaToIndex(db, pTab->pSchema)].zDbSName;
+
+    /* Now search pTab for the exact column. */
+    for(iCol=0; iCol<pTab->nCol; iCol++) {
+      if( sqlite3StrICmp(pTab->aCol[iCol].zName, zColumn)==0 ){
+        break;
+      }
+    }
+    if( iCol==pTab->nCol ){
+      sqlite3DbFree(db, zErr);
+      zErr = sqlite3MPrintf(db, "no such column: \"%s\"", zColumn);
+      rc = SQLITE_ERROR;
+      sqlite3BtreeLeaveAll(db);
+      goto blob_open_out;
+    }
+
+    /* If the value is being opened for writing, check that the
+    ** column is not indexed, and that it is not part of a foreign key. 
+    */
+    if( wrFlag ){
+      const char *zFault = 0;
+      Index *pIdx;
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+      if( db->flags&SQLITE_ForeignKeys ){
+        /* Check that the column is not part of an FK child key definition. It
+        ** is not necessary to check if it is part of a parent key, as parent
+        ** key columns must be indexed. The check below will pick up this 
+        ** case.  */
+        FKey *pFKey;
+        for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){
+          int j;
+          for(j=0; j<pFKey->nCol; j++){
+            if( pFKey->aCol[j].iFrom==iCol ){
+              zFault = "foreign key";
+            }
+          }
+        }
+      }
+#endif
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        int j;
+        for(j=0; j<pIdx->nKeyCol; j++){
+          /* FIXME: Be smarter about indexes that use expressions */
+          if( pIdx->aiColumn[j]==iCol || pIdx->aiColumn[j]==XN_EXPR ){
+            zFault = "indexed";
+          }
+        }
+      }
+      if( zFault ){
+        sqlite3DbFree(db, zErr);
+        zErr = sqlite3MPrintf(db, "cannot open %s column for writing", zFault);
+        rc = SQLITE_ERROR;
+        sqlite3BtreeLeaveAll(db);
+        goto blob_open_out;
+      }
+    }
+
+    pBlob->pStmt = (sqlite3_stmt *)sqlite3VdbeCreate(pParse);
+    assert( pBlob->pStmt || db->mallocFailed );
+    if( pBlob->pStmt ){
+      
+      /* This VDBE program seeks a btree cursor to the identified 
+      ** db/table/row entry. The reason for using a vdbe program instead
+      ** of writing code to use the b-tree layer directly is that the
+      ** vdbe program will take advantage of the various transaction,
+      ** locking and error handling infrastructure built into the vdbe.
+      **
+      ** After seeking the cursor, the vdbe executes an OP_ResultRow.
+      ** Code external to the Vdbe then "borrows" the b-tree cursor and
+      ** uses it to implement the blob_read(), blob_write() and 
+      ** blob_bytes() functions.
+      **
+      ** The sqlite3_blob_close() function finalizes the vdbe program,
+      ** which closes the b-tree cursor and (possibly) commits the 
+      ** transaction.
+      */
+      static const int iLn = VDBE_OFFSET_LINENO(2);
+      static const VdbeOpList openBlob[] = {
+        {OP_TableLock,      0, 0, 0},  /* 0: Acquire a read or write lock */
+        {OP_OpenRead,       0, 0, 0},  /* 1: Open a cursor */
+        /* blobSeekToRow() will initialize r[1] to the desired rowid */
+        {OP_NotExists,      0, 5, 1},  /* 2: Seek the cursor to rowid=r[1] */
+        {OP_Column,         0, 0, 1},  /* 3  */
+        {OP_ResultRow,      1, 0, 0},  /* 4  */
+        {OP_Halt,           0, 0, 0},  /* 5  */
+      };
+      Vdbe *v = (Vdbe *)pBlob->pStmt;
+      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+      VdbeOp *aOp;
+
+      sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, wrFlag, 
+                           pTab->pSchema->schema_cookie,
+                           pTab->pSchema->iGeneration);
+      sqlite3VdbeChangeP5(v, 1);     
+      aOp = sqlite3VdbeAddOpList(v, ArraySize(openBlob), openBlob, iLn);
+
+      /* Make sure a mutex is held on the table to be accessed */
+      sqlite3VdbeUsesBtree(v, iDb); 
+
+      if( db->mallocFailed==0 ){
+        assert( aOp!=0 );
+        /* Configure the OP_TableLock instruction */
+#ifdef SQLITE_OMIT_SHARED_CACHE
+        aOp[0].opcode = OP_Noop;
+#else
+        aOp[0].p1 = iDb;
+        aOp[0].p2 = pTab->tnum;
+        aOp[0].p3 = wrFlag;
+        sqlite3VdbeChangeP4(v, 1, pTab->zName, P4_TRANSIENT);
+      }
+      if( db->mallocFailed==0 ){
+#endif
+
+        /* Remove either the OP_OpenWrite or OpenRead. Set the P2 
+        ** parameter of the other to pTab->tnum.  */
+        if( wrFlag ) aOp[1].opcode = OP_OpenWrite;
+        aOp[1].p2 = pTab->tnum;
+        aOp[1].p3 = iDb;   
+
+        /* Configure the number of columns. Configure the cursor to
+        ** think that the table has one more column than it really
+        ** does. An OP_Column to retrieve this imaginary column will
+        ** always return an SQL NULL. This is useful because it means
+        ** we can invoke OP_Column to fill in the vdbe cursors type 
+        ** and offset cache without causing any IO.
+        */
+        aOp[1].p4type = P4_INT32;
+        aOp[1].p4.i = pTab->nCol+1;
+        aOp[3].p2 = pTab->nCol;
+
+        pParse->nVar = 0;
+        pParse->nMem = 1;
+        pParse->nTab = 1;
+        sqlite3VdbeMakeReady(v, pParse);
+      }
+    }
+   
+    pBlob->iCol = iCol;
+    pBlob->db = db;
+    sqlite3BtreeLeaveAll(db);
+    if( db->mallocFailed ){
+      goto blob_open_out;
+    }
+    rc = blobSeekToRow(pBlob, iRow, &zErr);
+  } while( (++nAttempt)<SQLITE_MAX_SCHEMA_RETRY && rc==SQLITE_SCHEMA );
+
+blob_open_out:
+  if( rc==SQLITE_OK && db->mallocFailed==0 ){
+    *ppBlob = (sqlite3_blob *)pBlob;
+  }else{
+    if( pBlob && pBlob->pStmt ) sqlite3VdbeFinalize((Vdbe *)pBlob->pStmt);
+    sqlite3DbFree(db, pBlob);
+  }
+  sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : 0), zErr);
+  sqlite3DbFree(db, zErr);
+  sqlite3ParserReset(pParse);
+  sqlite3StackFree(db, pParse);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Close a blob handle that was previously created using
+** sqlite3_blob_open().
+*/
+int sqlite3_blob_close(sqlite3_blob *pBlob){
+  Incrblob *p = (Incrblob *)pBlob;
+  int rc;
+  sqlite3 *db;
+
+  if( p ){
+    db = p->db;
+    sqlite3_mutex_enter(db->mutex);
+    rc = sqlite3_finalize(p->pStmt);
+    sqlite3DbFree(db, p);
+    sqlite3_mutex_leave(db->mutex);
+  }else{
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Perform a read or write operation on a blob
+*/
+static int blobReadWrite(
+  sqlite3_blob *pBlob, 
+  void *z, 
+  int n, 
+  int iOffset, 
+  int (*xCall)(BtCursor*, u32, u32, void*)
+){
+  int rc;
+  Incrblob *p = (Incrblob *)pBlob;
+  Vdbe *v;
+  sqlite3 *db;
+
+  if( p==0 ) return SQLITE_MISUSE_BKPT;
+  db = p->db;
+  sqlite3_mutex_enter(db->mutex);
+  v = (Vdbe*)p->pStmt;
+
+  if( n<0 || iOffset<0 || ((sqlite3_int64)iOffset+n)>p->nByte ){
+    /* Request is out of range. Return a transient error. */
+    rc = SQLITE_ERROR;
+  }else if( v==0 ){
+    /* If there is no statement handle, then the blob-handle has
+    ** already been invalidated. Return SQLITE_ABORT in this case.
+    */
+    rc = SQLITE_ABORT;
+  }else{
+    /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is
+    ** returned, clean-up the statement handle.
+    */
+    assert( db == v->db );
+    sqlite3BtreeEnterCursor(p->pCsr);
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+    if( xCall==sqlite3BtreePutData && db->xPreUpdateCallback ){
+      /* If a pre-update hook is registered and this is a write cursor, 
+      ** invoke it here. 
+      ** 
+      ** TODO: The preupdate-hook is passed SQLITE_DELETE, even though this
+      ** operation should really be an SQLITE_UPDATE. This is probably
+      ** incorrect, but is convenient because at this point the new.* values 
+      ** are not easily obtainable. And for the sessions module, an 
+      ** SQLITE_UPDATE where the PK columns do not change is handled in the 
+      ** same way as an SQLITE_DELETE (the SQLITE_DELETE code is actually
+      ** slightly more efficient). Since you cannot write to a PK column
+      ** using the incremental-blob API, this works. For the sessions module
+      ** anyhow.
+      */
+      sqlite3_int64 iKey;
+      iKey = sqlite3BtreeIntegerKey(p->pCsr);
+      sqlite3VdbePreUpdateHook(
+          v, v->apCsr[0], SQLITE_DELETE, p->zDb, p->pTab, iKey, -1
+      );
+    }
+#endif
+
+    rc = xCall(p->pCsr, iOffset+p->iOffset, n, z);
+    sqlite3BtreeLeaveCursor(p->pCsr);
+    if( rc==SQLITE_ABORT ){
+      sqlite3VdbeFinalize(v);
+      p->pStmt = 0;
+    }else{
+      v->rc = rc;
+    }
+  }
+  sqlite3Error(db, rc);
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Read data from a blob handle.
+*/
+int sqlite3_blob_read(sqlite3_blob *pBlob, void *z, int n, int iOffset){
+  return blobReadWrite(pBlob, z, n, iOffset, sqlite3BtreePayloadChecked);
+}
+
+/*
+** Write data to a blob handle.
+*/
+int sqlite3_blob_write(sqlite3_blob *pBlob, const void *z, int n, int iOffset){
+  return blobReadWrite(pBlob, (void *)z, n, iOffset, sqlite3BtreePutData);
+}
+
+/*
+** Query a blob handle for the size of the data.
+**
+** The Incrblob.nByte field is fixed for the lifetime of the Incrblob
+** so no mutex is required for access.
+*/
+int sqlite3_blob_bytes(sqlite3_blob *pBlob){
+  Incrblob *p = (Incrblob *)pBlob;
+  return (p && p->pStmt) ? p->nByte : 0;
+}
+
+/*
+** Move an existing blob handle to point to a different row of the same
+** database table.
+**
+** If an error occurs, or if the specified row does not exist or does not
+** contain a blob or text value, then an error code is returned and the
+** database handle error code and message set. If this happens, then all 
+** subsequent calls to sqlite3_blob_xxx() functions (except blob_close()) 
+** immediately return SQLITE_ABORT.
+*/
+int sqlite3_blob_reopen(sqlite3_blob *pBlob, sqlite3_int64 iRow){
+  int rc;
+  Incrblob *p = (Incrblob *)pBlob;
+  sqlite3 *db;
+
+  if( p==0 ) return SQLITE_MISUSE_BKPT;
+  db = p->db;
+  sqlite3_mutex_enter(db->mutex);
+
+  if( p->pStmt==0 ){
+    /* If there is no statement handle, then the blob-handle has
+    ** already been invalidated. Return SQLITE_ABORT in this case.
+    */
+    rc = SQLITE_ABORT;
+  }else{
+    char *zErr;
+    rc = blobSeekToRow(p, iRow, &zErr);
+    if( rc!=SQLITE_OK ){
+      sqlite3ErrorWithMsg(db, rc, (zErr ? "%s" : 0), zErr);
+      sqlite3DbFree(db, zErr);
+    }
+    assert( rc!=SQLITE_SCHEMA );
+  }
+
+  rc = sqlite3ApiExit(db, rc);
+  assert( rc==SQLITE_OK || p->pStmt==0 );
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+#endif /* #ifndef SQLITE_OMIT_INCRBLOB */