Import SQLite 3.8.7.4.

third_party/sqlite/src/tool/showdb.c

 /*
 ** A utility for printing all or part of an SQLite database file.
 */
 #include <stdio.h>
 #include <ctype.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+
+#if !defined(_MSC_VER)
 #include <unistd.h>
+#else
+#include <io.h>
+#endif
+
 #include <stdlib.h>
 #include <string.h>
+#include "sqlite3.h"
 
 
 static int pagesize = 1024;     /* Size of a database page */
 static int db = -1;             /* File descriptor for reading the DB */
 static int mxPage = 0;          /* Last page number */
 static int perLine = 16;        /* HEX elements to print per line */
 
 typedef long long int i64;      /* Datatype for 64-bit integers */
 
 
@@ skipping 32 matching lines @@
 **
 ** Space to hold the content is obtained from malloc() and needs to be
 ** freed by the caller.
 */
 static unsigned char *getContent(int ofst, int nByte){
   unsigned char *aData;
   aData = malloc(nByte+32);
   if( aData==0 ) out_of_memory();
   memset(aData, 0, nByte+32);
   lseek(db, ofst, SEEK_SET);
-  read(db, aData, nByte);
+  if( read(db, aData, nByte)<nByte ) memset(aData, 0, nByte);
   return aData;
 }
 
 /*
 ** Print a range of bytes as hex and as ascii.
 */
 static unsigned char *print_byte_range(
   int ofst,          /* First byte in the range of bytes to print */
   int nByte,         /* Number of bytes to print */
   int printOfst      /* Add this amount to the index on the left column */
@@ skipping 32 matching lines @@
       }
     }
     fprintf(stdout,"\n");
   }
   return aData;
 }
 
 /*
 ** Print an entire page of content as hex
 */
-static print_page(int iPg){
+static void print_page(int iPg){
   int iStart;
   unsigned char *aData;
   iStart = (iPg-1)*pagesize;
   fprintf(stdout, "Page %d:   (offsets 0x%x..0x%x)\n",
           iPg, iStart, iStart+pagesize-1);
   aData = print_byte_range(iStart, pagesize, 0);
   free(aData);
 }
 
+
 /* Print a line of decode output showing a 4-byte integer.
 */
-static print_decode_line(
+static void print_decode_line(
   unsigned char *aData,      /* Content being decoded */
   int ofst, int nByte,       /* Start and size of decode */
   const char *zMsg           /* Message to append */
 ){
   int i, j;
   int val = aData[ofst];
   char zBuf[100];
   sprintf(zBuf, " %03x: %02x", ofst, aData[ofst]);
-  i = strlen(zBuf);
+  i = (int)strlen(zBuf);
   for(j=1; j<4; j++){
     if( j>=nByte ){
       sprintf(&zBuf[i], "   ");
     }else{
       sprintf(&zBuf[i], " %02x", aData[ofst+j]);
       val = val*256 + aData[ofst+j];
     }
-    i += strlen(&zBuf[i]);
+    i += (int)strlen(&zBuf[i]);
   }
   sprintf(&zBuf[i], "   %9d", val);
   printf("%s  %s\n", zBuf, zMsg);
 }
 
 /*
 ** Decode the database header.
 */
 static void print_db_header(void){
   unsigned char *aData;
   aData = print_byte_range(0, 100, 0);
   printf("Decoded:\n");
   print_decode_line(aData, 16, 2, "Database page size");
   print_decode_line(aData, 18, 1, "File format write version");
   print_decode_line(aData, 19, 1, "File format read version");
   print_decode_line(aData, 20, 1, "Reserved space at end of page");
   print_decode_line(aData, 24, 4, "File change counter");
   print_decode_line(aData, 28, 4, "Size of database in pages");
   print_decode_line(aData, 32, 4, "Page number of first freelist page");
   print_decode_line(aData, 36, 4, "Number of freelist pages");
   print_decode_line(aData, 40, 4, "Schema cookie");
   print_decode_line(aData, 44, 4, "Schema format version");
   print_decode_line(aData, 48, 4, "Default page cache size");
   print_decode_line(aData, 52, 4, "Largest auto-vac root page");
   print_decode_line(aData, 56, 4, "Text encoding");
   print_decode_line(aData, 60, 4, "User version");
   print_decode_line(aData, 64, 4, "Incremental-vacuum mode");
-  print_decode_line(aData, 68, 4, "meta[7]");
+  print_decode_line(aData, 68, 4, "Application ID");
   print_decode_line(aData, 72, 4, "meta[8]");
   print_decode_line(aData, 76, 4, "meta[9]");
   print_decode_line(aData, 80, 4, "meta[10]");
   print_decode_line(aData, 84, 4, "meta[11]");
   print_decode_line(aData, 88, 4, "meta[12]");
   print_decode_line(aData, 92, 4, "Change counter for version number");
   print_decode_line(aData, 96, 4, "SQLite version number");
 }
 
 /*
 ** Describe cell content.
 */
-static int describeContent(
+static i64 describeContent(
   unsigned char *a,       /* Cell content */
-  int nLocal,             /* Bytes in a[] */
+  i64 nLocal,             /* Bytes in a[] */
   char *zDesc             /* Write description here */
 ){
-  int nDesc = 0;
-  int n, i, j;
-  i64 x, v;
+  i64 nDesc = 0;
+  int n, j;
+  i64 i, x, v;
   const unsigned char *pData;
   const unsigned char *pLimit;
   char sep = ' ';
 
   pLimit = &a[nLocal];
   n = decodeVarint(a, &x);
   pData = &a[x];
   a += n;
   i = x - n;
   while( i>0 && pData<=pLimit ){
@@ skipping 19 matching lines @@
       }
       sprintf(zDesc, "%lld", v);
     }else if( x==7 ){
       sprintf(zDesc, "real");
       pData += 8;
     }else if( x==8 ){
       sprintf(zDesc, "0");
     }else if( x==9 ){
       sprintf(zDesc, "1");
     }else if( x>=12 ){
-      int size = (x-12)/2;
+      i64 size = (x-12)/2;
       if( (x&1)==0 ){
-        sprintf(zDesc, "blob(%d)", size);
+        sprintf(zDesc, "blob(%lld)", size);
       }else{
-        sprintf(zDesc, "txt(%d)", size);
+        sprintf(zDesc, "txt(%lld)", size);
       }
       pData += size;
     }
-    j = strlen(zDesc);
+    j = (int)strlen(zDesc);
     zDesc += j;
     nDesc += j;
   }
   return nDesc;
 }
 
 /*
 ** Compute the local payload size given the total payload size and
 ** the page size.
 */
-static int localPayload(i64 nPayload, char cType){
-  int maxLocal;
-  int minLocal;
-  int surplus;
-  int nLocal;
+static i64 localPayload(i64 nPayload, char cType){
+  i64 maxLocal;
+  i64 minLocal;
+  i64 surplus;
+  i64 nLocal;
   if( cType==13 ){
     /* Table leaf */
     maxLocal = pagesize-35;
     minLocal = (pagesize-12)*32/255-23;
   }else{
     maxLocal = (pagesize-12)*64/255-23;
     minLocal = (pagesize-12)*32/255-23;
   }
   if( nPayload>maxLocal ){
     surplus = minLocal + (nPayload-minLocal)%(pagesize-4);
     if( surplus<=maxLocal ){
       nLocal = surplus;
     }else{
       nLocal = minLocal;
     }
   }else{
     nLocal = nPayload;
   }
   return nLocal;
 }
   
 
 /*
 ** Create a description for a single cell.
 **
 ** The return value is the local cell size.
 */
-static int describeCell(
+static i64 describeCell(
   unsigned char cType,    /* Page type */
   unsigned char *a,       /* Cell content */
   int showCellContent,    /* Show cell content if true */
   char **pzDesc           /* Store description here */
 ){
   int i;
-  int nDesc = 0;
+  i64 nDesc = 0;
   int n = 0;
   int leftChild;
   i64 nPayload;
   i64 rowid;
-  int nLocal;
+  i64 nLocal;
   static char zDesc[1000];
   i = 0;
   if( cType<=5 ){
     leftChild = ((a[0]*256 + a[1])*256 + a[2])*256 + a[3];
     a += 4;
     n += 4;
     sprintf(zDesc, "lx: %d ", leftChild);
     nDesc = strlen(zDesc);
   }
   if( cType!=5 ){
@@ skipping 21 matching lines @@
     nDesc += strlen(&zDesc[nDesc]);
     n += 4;
   }
   if( showCellContent && cType!=5 ){
     nDesc += describeContent(a, nLocal, &zDesc[nDesc-1]);
   }
   *pzDesc = zDesc;
   return nLocal+n;
 }
 
+/* Print an offset followed by nByte bytes.  Add extra white-space
+** at the end so that subsequent text is aligned.
+*/
+static void printBytes(
+  unsigned char *aData,      /* Content being decoded */
+  unsigned char *aStart,     /* Start of content to be printed */
+  int nByte                  /* Number of bytes to print */
+){
+  int j;
+  printf(" %03x: ", (int)(aStart-aData));
+  for(j=0; j<9; j++){
+    if( j>=nByte ){
+      printf("   ");
+    }else{
+      printf("%02x ", aStart[j]);
+    }
+  }
+}
+
+
+/*
+** Write a full decode on stdout for the cell at a[ofst].
+** Assume the page contains a header of size szPgHdr bytes.
+*/
+static void decodeCell(
+  unsigned char *a,       /* Page content (without the page-1 header) */
+  unsigned pgno,          /* Page number */
+  int iCell,              /* Cell index */
+  int szPgHdr,            /* Size of the page header.  0 or 100 */
+  int ofst                /* Cell begins at a[ofst] */
+){
+  int i, j;
+  int leftChild;
+  i64 k;
+  i64 nPayload;
+  i64 rowid;
+  i64 nHdr;
+  i64 iType;
+  i64 nLocal;
+  unsigned char *x = a + ofst;
+  unsigned char *end;
+  unsigned char cType = a[0];
+  int nCol = 0;
+  int szCol[2000];
+  int ofstCol[2000];
+  int typeCol[2000];
+
+  printf("Cell[%d]:\n", iCell);
+  if( cType<=5 ){
+    leftChild = ((x[0]*256 + x[1])*256 + x[2])*256 + x[3];
+    printBytes(a, x, 4);
+    printf("left child page:: %d\n", leftChild);
+    x += 4;
+  }
+  if( cType!=5 ){
+    i = decodeVarint(x, &nPayload);
+    printBytes(a, x, i);
+    nLocal = localPayload(nPayload, cType);
+    if( nLocal==nPayload ){
+      printf("payload-size: %lld\n", nPayload);
+    }else{
+      printf("payload-size: %lld (%lld local, %lld overflow)\n",
+             nPayload, nLocal, nPayload-nLocal);
+    }
+    x += i;
+  }else{
+    nPayload = nLocal = 0;
+  }
+  end = x + nLocal;
+  if( cType==5 || cType==13 ){
+    i = decodeVarint(x, &rowid);
+    printBytes(a, x, i);
+    printf("rowid: %lld\n", rowid);
+    x += i;
+  }
+  if( nLocal>0 ){
+    i = decodeVarint(x, &nHdr);
+    printBytes(a, x, i);
+    printf("record-header-size: %d\n", (int)nHdr);
+    j = i;
+    nCol = 0;
+    k = nHdr;
+    while( x+j<end && j<nHdr ){
+       const char *zTypeName;
+       int sz = 0;
+       char zNm[30];
+       i = decodeVarint(x+j, &iType);
+       printBytes(a, x+j, i);
+       printf("typecode[%d]: %d - ", nCol, (int)iType);
+       switch( iType ){
+         case 0:  zTypeName = "NULL";    sz = 0;  break;
+         case 1:  zTypeName = "int8";    sz = 1;  break;
+         case 2:  zTypeName = "int16";   sz = 2;  break;
+         case 3:  zTypeName = "int24";   sz = 3;  break;
+         case 4:  zTypeName = "int32";   sz = 4;  break;
+         case 5:  zTypeName = "int48";   sz = 6;  break;
+         case 6:  zTypeName = "int64";   sz = 8;  break;
+         case 7:  zTypeName = "double";  sz = 8;  break;
+         case 8:  zTypeName = "zero";    sz = 0;  break;
+         case 9:  zTypeName = "one";     sz = 0;  break;
+         case 10:
+         case 11: zTypeName = "error";   sz = 0;  break;
+         default: {
+           sz = (int)(iType-12)/2;
+           sprintf(zNm, (iType&1)==0 ? "blob(%d)" : "text(%d)", sz);
+           zTypeName = zNm;
+           break;
+         }
+       }
+       printf("%s\n", zTypeName);
+       szCol[nCol] = sz;
+       ofstCol[nCol] = (int)k;
+       typeCol[nCol] = (int)iType;
+       k += sz;
+       nCol++;
+       j += i;
+    }
+    for(i=0; i<nCol && ofstCol[i]+szCol[i]<=nLocal; i++){
+       int s = ofstCol[i];
+       i64 v;
+       const unsigned char *pData;
+       if( szCol[i]==0 ) continue;
+       printBytes(a, x+s, szCol[i]);
+       printf("data[%d]: ", i);
+       pData = x+s;
+       if( typeCol[i]<=7 ){
+         v = (signed char)pData[0];
+         for(k=1; k<szCol[i]; k++){
+           v = (v<<8) + pData[k];
+         }
+         if( typeCol[i]==7 ){
+           double r;
+           memcpy(&r, &v, sizeof(r));
+           printf("%#g\n", r);
+         }else{
+           printf("%lld\n", v);
+         }
+       }else{
+         int ii, jj;
+         char zConst[32];
+         if( (typeCol[i]&1)==0 ){
+           zConst[0] = 'x';
+           zConst[1] = '\'';
+           for(ii=2, jj=0; jj<szCol[i] && ii<24; jj++, ii+=2){
+             sprintf(zConst+ii, "%02x", pData[jj]);
+           }
+         }else{
+           zConst[0] = '\'';
+           for(ii=1, jj=0; jj<szCol[i] && ii<24; jj++, ii++){
+             zConst[ii] = isprint(pData[jj]) ? pData[jj] : '.';
+           }
+           zConst[ii] = 0;
+         }
+         if( jj<szCol[i] ){
+           memcpy(zConst+ii, "...'", 5);
+         }else{
+           memcpy(zConst+ii, "'", 2);
+         }
+         printf("%s\n", zConst);
+       }
+       j = ofstCol[i] + szCol[i];
+    }
+  }
+  if( j<nLocal ){
+    printBytes(a, x+j, 0);
+    printf("... %lld bytes of content ...\n", nLocal-j);
+  }
+  if( nLocal<nPayload ){
+    printBytes(a, x+nLocal, 4);
+    printf("overflow-page: %d\n", decodeInt32(x+nLocal));
+  }
+}
+
+
 /*
 ** Decode a btree page
 */
 static void decode_btree_page(
   unsigned char *a,   /* Page content */
   int pgno,           /* Page number */
   int hdrSize,        /* Size of the page header.  0 or 100 */
   char *zArgs         /* Flags to control formatting */
 ){
   const char *zType = "unknown";
   int nCell;
   int i, j;
   int iCellPtr;
   int showCellContent = 0;
   int showMap = 0;
+  int cellToDecode = -2;
   char *zMap = 0;
   switch( a[0] ){
     case 2:  zType = "index interior node";  break;
     case 5:  zType = "table interior node";  break;
     case 10: zType = "index leaf";           break;
     case 13: zType = "table leaf";           break;
   }
   while( zArgs[0] ){
     switch( zArgs[0] ){
       case 'c': showCellContent = 1;  break;
       case 'm': showMap = 1;          break;
+      case 'd': {
+        if( !isdigit(zArgs[1]) ){
+          cellToDecode = -1;
+        }else{
+          cellToDecode = 0;
+          while( isdigit(zArgs[1]) ){
+            zArgs++;
+            cellToDecode = cellToDecode*10 + zArgs[0] - '0';
+          }
+        }
+        break;
+      }
     }
     zArgs++;
   }
-  printf("Decode of btree page %d:\n", pgno);
+  nCell = a[3]*256 + a[4];
+  iCellPtr = (a[0]==2 || a[0]==5) ? 12 : 8;
+  if( cellToDecode>=nCell ){
+    printf("Page %d has only %d cells\n", pgno, nCell);
+    return;
+  }
+  printf("Header on btree page %d:\n", pgno);
   print_decode_line(a, 0, 1, zType);
   print_decode_line(a, 1, 2, "Offset to first freeblock");
   print_decode_line(a, 3, 2, "Number of cells on this page");
-  nCell = a[3]*256 + a[4];
   print_decode_line(a, 5, 2, "Offset to cell content area");
   print_decode_line(a, 7, 1, "Fragmented byte count");
   if( a[0]==2 || a[0]==5 ){
     print_decode_line(a, 8, 4, "Right child");
-    iCellPtr = 12;
-  }else{
-    iCellPtr = 8;
   }
-  if( nCell>0 ){
+  if( cellToDecode==(-2) && nCell>0 ){
     printf(" key: lx=left-child n=payload-size r=rowid\n");
   }
   if( showMap ){
     zMap = malloc(pagesize);
     memset(zMap, '.', pagesize);
     memset(zMap, '1', hdrSize);
     memset(&zMap[hdrSize], 'H', iCellPtr);
     memset(&zMap[hdrSize+iCellPtr], 'P', 2*nCell);
   }
   for(i=0; i<nCell; i++){
     int cofst = iCellPtr + i*2;
     char *zDesc;
-    int n;
+    i64 n;
 
     cofst = a[cofst]*256 + a[cofst+1];
     n = describeCell(a[0], &a[cofst-hdrSize], showCellContent, &zDesc);
     if( showMap ){
       char zBuf[30];
-      memset(&zMap[cofst], '*', n);
+      memset(&zMap[cofst], '*', (size_t)n);
       zMap[cofst] = '[';
       zMap[cofst+n-1] = ']';
       sprintf(zBuf, "%d", i);
-      j = strlen(zBuf);
+      j = (int)strlen(zBuf);
       if( j<=n-2 ) memcpy(&zMap[cofst+1], zBuf, j);
     }
-    printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
+    if( cellToDecode==(-2) ){
+      printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
+    }else if( cellToDecode==(-1) || cellToDecode==i ){
+      decodeCell(a, pgno, i, hdrSize, cofst-hdrSize);
+    }
   }
   if( showMap ){
+    printf("Page map:  (H=header P=cell-index 1=page-1-header .=free-space)\n");
     for(i=0; i<pagesize; i+=64){
       printf(" %03x: %.64s\n", i, &zMap[i]);
     }
     free(zMap);
-  }  
+  }
 }
 
 /*
 ** Decode a freelist trunk page.
 */
 static void decode_trunk_page(
   int pgno,             /* The page number */
   int pagesize,         /* Size of each page */
   int detail,           /* Show leaf pages if true */
   int recursive         /* Follow the trunk change if true */
 ){
-  int n, i, k;
+  int n, i;
   unsigned char *a;
   while( pgno>0 ){
     a = getContent((pgno-1)*pagesize, pagesize);
     printf("Decode of freelist trunk page %d:\n", pgno);
     print_decode_line(a, 0, 4, "Next freelist trunk page");
     print_decode_line(a, 4, 4, "Number of entries on this page");
     if( detail ){
       n = (int)decodeInt32(&a[4]);
       for(i=0; i<n; i++){
         unsigned int x = decodeInt32(&a[8+4*i]);
         char zIdx[10];
         sprintf(zIdx, "[%d]", i);
         printf("  %5s %7u", zIdx, x);
         if( i%5==4 ) printf("\n");
       }
       if( i%5!=0 ) printf("\n");
     }
     if( !recursive ){
       pgno = 0;
     }else{
       pgno = (int)decodeInt32(&a[0]);
     }
     free(a);
   }
 }
 
 /*
+** A short text comment on the use of each page.
+*/
+static char **zPageUse;
+
+/*
+** Add a comment on the use of a page.
+*/
+static void page_usage_msg(int pgno, const char *zFormat, ...){
+  va_list ap;
+  char *zMsg;
+
+  va_start(ap, zFormat);
+  zMsg = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+  if( pgno<=0 || pgno>mxPage ){
+    printf("ERROR: page %d out of range 1..%d: %s\n",
+            pgno, mxPage, zMsg);
+    sqlite3_free(zMsg);
+    return;
+  }
+  if( zPageUse[pgno]!=0 ){
+    printf("ERROR: page %d used multiple times:\n", pgno);
+    printf("ERROR:    previous: %s\n", zPageUse[pgno]);
+    printf("ERROR:    current:  %s\n", zMsg);
+    sqlite3_free(zPageUse[pgno]);
+  }
+  zPageUse[pgno] = zMsg;
+}
+
+/*
+** Find overflow pages of a cell and describe their usage.
+*/
+static void page_usage_cell(
+  unsigned char cType,    /* Page type */
+  unsigned char *a,       /* Cell content */
+  int pgno,               /* page containing the cell */
+  int cellno              /* Index of the cell on the page */
+){
+  int i;
+  int n = 0;
+  i64 nPayload;
+  i64 rowid;
+  i64 nLocal;
+  i = 0;
+  if( cType<=5 ){
+    a += 4;
+    n += 4;
+  }
+  if( cType!=5 ){
+    i = decodeVarint(a, &nPayload);
+    a += i;
+    n += i;
+    nLocal = localPayload(nPayload, cType);
+  }else{
+    nPayload = nLocal = 0;
+  }
+  if( cType==5 || cType==13 ){
+    i = decodeVarint(a, &rowid);
+    a += i;
+    n += i;
+  }
+  if( nLocal<nPayload ){
+    int ovfl = decodeInt32(a+nLocal);
+    int cnt = 0;
+    while( ovfl && (cnt++)<mxPage ){
+      page_usage_msg(ovfl, "overflow %d from cell %d of page %d",
+                     cnt, cellno, pgno);
+      a = getContent((ovfl-1)*pagesize, 4);
+      ovfl = decodeInt32(a);
+      free(a);
+    }
+  }
+}
+
+
+/*
+** Describe the usages of a b-tree page
+*/
+static void page_usage_btree(
+  int pgno,             /* Page to describe */
+  int parent,           /* Parent of this page.  0 for root pages */
+  int idx,              /* Which child of the parent */
+  const char *zName     /* Name of the table */
+){
+  unsigned char *a;
+  const char *zType = "corrupt node";
+  int nCell;
+  int i;
+  int hdr = pgno==1 ? 100 : 0;
+
+  if( pgno<=0 || pgno>mxPage ) return;
+  a = getContent((pgno-1)*pagesize, pagesize);
+  switch( a[hdr] ){
+    case 2:  zType = "interior node of index";  break;
+    case 5:  zType = "interior node of table";  break;
+    case 10: zType = "leaf of index";           break;
+    case 13: zType = "leaf of table";           break;
+  }
+  if( parent ){
+    page_usage_msg(pgno, "%s [%s], child %d of page %d",
+                   zType, zName, idx, parent);
+  }else{
+    page_usage_msg(pgno, "root %s [%s]", zType, zName);
+  }
+  nCell = a[hdr+3]*256 + a[hdr+4];
+  if( a[hdr]==2 || a[hdr]==5 ){
+    int cellstart = hdr+12;
+    unsigned int child;
+    for(i=0; i<nCell; i++){
+      int ofst;
+
+      ofst = cellstart + i*2;
+      ofst = a[ofst]*256 + a[ofst+1];
+      child = decodeInt32(a+ofst);
+      page_usage_btree(child, pgno, i, zName);
+    }
+    child = decodeInt32(a+cellstart-4);
+    page_usage_btree(child, pgno, i, zName);
+  }
+  if( a[hdr]==2 || a[hdr]==10 || a[hdr]==13 ){
+    int cellstart = hdr + 8 + 4*(a[hdr]<=5);
+    for(i=0; i<nCell; i++){
+      int ofst;
+      ofst = cellstart + i*2;
+      ofst = a[ofst]*256 + a[ofst+1];
+      page_usage_cell(a[hdr], a+ofst, pgno, i);
+    }
+  }
+  free(a);
+}
+
+/*
+** Determine page usage by the freelist
+*/
+static void page_usage_freelist(int pgno){
+  unsigned char *a;
+  int cnt = 0;
+  int i;
+  int n;
+  int iNext;
+  int parent = 1;
+
+  while( pgno>0 && pgno<=mxPage && (cnt++)<mxPage ){
+    page_usage_msg(pgno, "freelist trunk #%d child of %d", cnt, parent);
+    a = getContent((pgno-1)*pagesize, pagesize);
+    iNext = decodeInt32(a);
+    n = decodeInt32(a+4);
+    for(i=0; i<n; i++){
+      int child = decodeInt32(a + (i*4+8));
+      page_usage_msg(child, "freelist leaf, child %d of trunk page %d",
+                     i, pgno);
+    }
+    free(a);
+    parent = pgno;
+    pgno = iNext;
+  }
+}
+
+/*
+** Determine pages used as PTRMAP pages
+*/
+static void page_usage_ptrmap(unsigned char *a){
+  if( a[55] ){
+    int usable = pagesize - a[20];
+    int pgno = 2;
+    int perPage = usable/5;
+    while( pgno<=mxPage ){
+      page_usage_msg(pgno, "PTRMAP page covering %d..%d",
+                           pgno+1, pgno+perPage);
+      pgno += perPage + 1;
+    }
+  }
+}
+
+/*
+** Try to figure out how every page in the database file is being used.
+*/
+static void page_usage_report(const char *zDbName){
+  int i, j;
+  int rc;
+  sqlite3 *db;
+  sqlite3_stmt *pStmt;
+  unsigned char *a;
+  char zQuery[200];
+
+  /* Avoid the pathological case */
+  if( mxPage<1 ){
+    printf("empty database\n");
+    return;
+  }
+
+  /* Open the database file */
+  rc = sqlite3_open(zDbName, &db);
+  if( rc ){
+    printf("cannot open database: %s\n", sqlite3_errmsg(db));
+    sqlite3_close(db);
+    return;
+  }
+
+  /* Set up global variables zPageUse[] and mxPage to record page
+  ** usages */
+  zPageUse = sqlite3_malloc( sizeof(zPageUse[0])*(mxPage+1) );
+  if( zPageUse==0 ) out_of_memory();
+  memset(zPageUse, 0, sizeof(zPageUse[0])*(mxPage+1));
+
+  /* Discover the usage of each page */
+  a = getContent(0, 100);
+  page_usage_freelist(decodeInt32(a+32));
+  page_usage_ptrmap(a);
+  free(a);
+  page_usage_btree(1, 0, 0, "sqlite_master");
+  sqlite3_exec(db, "PRAGMA writable_schema=ON", 0, 0, 0);
+  for(j=0; j<2; j++){
+    sqlite3_snprintf(sizeof(zQuery), zQuery,
+             "SELECT type, name, rootpage FROM SQLITE_MASTER WHERE rootpage"
+             " ORDER BY rowid %s", j?"DESC":"");
+    rc = sqlite3_prepare_v2(db, zQuery, -1, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      while( sqlite3_step(pStmt)==SQLITE_ROW ){
+        int pgno = sqlite3_column_int(pStmt, 2);
+        page_usage_btree(pgno, 0, 0, (const char*)sqlite3_column_text(pStmt,1));
+      }
+    }else{
+      printf("ERROR: cannot query database: %s\n", sqlite3_errmsg(db));
+    }
+    rc = sqlite3_finalize(pStmt);
+    if( rc==SQLITE_OK ) break;
+  }
+  sqlite3_close(db);
+
+  /* Print the report and free memory used */
+  for(i=1; i<=mxPage; i++){
+    printf("%5d: %s\n", i, zPageUse[i] ? zPageUse[i] : "???");
+    sqlite3_free(zPageUse[i]);
+  }
+  sqlite3_free(zPageUse);
+  zPageUse = 0;
+}
+
+/*
+** Try to figure out how every page in the database file is being used.
+*/
+static void ptrmap_coverage_report(const char *zDbName){
+  int pgno;
+  unsigned char *aHdr;
+  unsigned char *a;
+  int usable;
+  int perPage;
+  int i;
+
+  /* Avoid the pathological case */
+  if( mxPage<1 ){
+    printf("empty database\n");
+    return;
+  }
+
+  /* Make sure PTRMAPs are used in this database */
+  aHdr = getContent(0, 100);
+  if( aHdr[55]==0 ){
+    printf("database does not use PTRMAP pages\n");
+    return;
+  }
+  usable = pagesize - aHdr[20];
+  perPage = usable/5;
+  free(aHdr);
+  printf("%5d: root of sqlite_master\n", 1);
+  for(pgno=2; pgno<=mxPage; pgno += perPage+1){
+    printf("%5d: PTRMAP page covering %d..%d\n", pgno,
+           pgno+1, pgno+perPage);
+    a = getContent((pgno-1)*pagesize, usable);
+    for(i=0; i+5<=usable && pgno+1+i/5<=mxPage; i+=5){
+      const char *zType = "???";
+      unsigned int iFrom = decodeInt32(&a[i+1]);
+      switch( a[i] ){
+        case 1:  zType = "b-tree root page";        break;
+        case 2:  zType = "freelist page";           break;
+        case 3:  zType = "first page of overflow";  break;
+        case 4:  zType = "later page of overflow";  break;
+        case 5:  zType = "b-tree non-root page";    break;
+      }
+      printf("%5d: %s, parent=%u\n", pgno+1+i/5, zType, iFrom);
+    }
+    free(a);
+  }
+}
+
+/*
 ** Print a usage comment
 */
 static void usage(const char *argv0){
   fprintf(stderr, "Usage %s FILENAME ?args...?\n\n", argv0);
   fprintf(stderr,
     "args:\n"
     "    dbheader        Show database header\n"
+    "    pgidx           Index of how each page is used\n"
+    "    ptrmap          Show all PTRMAP page content\n"
     "    NNN..MMM        Show hex of pages NNN through MMM\n"
     "    NNN..end        Show hex of pages NNN through end of file\n"
     "    NNNb            Decode btree page NNN\n"
     "    NNNbc           Decode btree page NNN and show content\n"
     "    NNNbm           Decode btree page NNN and show a layout map\n"
+    "    NNNbdCCC        Decode cell CCC on btree page NNN\n"
     "    NNNt            Decode freelist trunk page NNN\n"
-    "    NNNtd           Show leave freelist pages on the decode\n"
-    "    NNNtr           Recurisvely decode freelist starting at NNN\n"
+    "    NNNtd           Show leaf freelist pages on the decode\n"
+    "    NNNtr           Recursively decode freelist starting at NNN\n"
   );
 }
 
 int main(int argc, char **argv){
   struct stat sbuf;
   unsigned char zPgSz[2];
   if( argc<2 ){
     usage(argv[0]);
     exit(1);
   }
   db = open(argv[1], O_RDONLY);
   if( db<0 ){
     fprintf(stderr,"%s: can't open %s\n", argv[0], argv[1]);
     exit(1);
   }
   zPgSz[0] = 0;
   zPgSz[1] = 0;
   lseek(db, 16, SEEK_SET);
-  read(db, zPgSz, 2);
+  if( read(db, zPgSz, 2)<2 ) memset(zPgSz, 0, 2);
   pagesize = zPgSz[0]*256 + zPgSz[1]*65536;
   if( pagesize==0 ) pagesize = 1024;
   printf("Pagesize: %d\n", pagesize);
   fstat(db, &sbuf);
   mxPage = sbuf.st_size/pagesize;
   printf("Available pages: 1..%d\n", mxPage);
   if( argc==2 ){
     int i;
     for(i=1; i<=mxPage; i++) print_page(i);
   }else{
     int i;
     for(i=2; i<argc; i++){
       int iStart, iEnd;
       char *zLeft;
       if( strcmp(argv[i], "dbheader")==0 ){
         print_db_header();
         continue;
       }
+      if( strcmp(argv[i], "pgidx")==0 ){
+        page_usage_report(argv[1]);
+        continue;
+      }
+      if( strcmp(argv[i], "ptrmap")==0 ){
+        ptrmap_coverage_report(argv[1]);
+        continue;
+      }
+      if( strcmp(argv[i], "help")==0 ){
+        usage(argv[0]);
+        continue;
+      }
       if( !isdigit(argv[i][0]) ){
         fprintf(stderr, "%s: unknown option: [%s]\n", argv[0], argv[i]);
         continue;
       }
       iStart = strtol(argv[i], &zLeft, 0);
       if( zLeft && strcmp(zLeft,"..end")==0 ){
         iEnd = mxPage;
       }else if( zLeft && zLeft[0]=='.' && zLeft[1]=='.' ){
         iEnd = strtol(&zLeft[2], 0, 0);
       }else if( zLeft && zLeft[0]=='b' ){
         int ofst, nByte, hdrSize;
         unsigned char *a;
         if( iStart==1 ){
           ofst = hdrSize = 100;
           nByte = pagesize-100;
         }else{
           hdrSize = 0;
           ofst = (iStart-1)*pagesize;
           nByte = pagesize;
         }
         a = getContent(ofst, nByte);
         decode_btree_page(a, iStart, hdrSize, &zLeft[1]);
         free(a);
         continue;
       }else if( zLeft && zLeft[0]=='t' ){
-        unsigned char *a;
         int detail = 0;
         int recursive = 0;
         int i;
         for(i=1; zLeft[i]; i++){
           if( zLeft[i]=='r' ) recursive = 1;
           if( zLeft[i]=='d' ) detail = 1;
         }
         decode_trunk_page(iStart, pagesize, detail, recursive);
         continue;
       }else{
         iEnd = iStart;
       }
       if( iStart<1 || iEnd<iStart || iEnd>mxPage ){
         fprintf(stderr,
           "Page argument should be LOWER?..UPPER?.  Range 1 to %d\n",
           mxPage);
         exit(1);
       }
       while( iStart<=iEnd ){
         print_page(iStart);
         iStart++;
       }
     }
   }
   close(db);
+  return 0;
 }