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Overview
Comment:Add btree-page decoding logic to showwal.c. Commands of the form: "showwal $FILE 123bmc" show the content of the btree page in frame 123. "b" means decode the btree. "c" means show cell content. "m" means give a map of the btree page.
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SHA1:93b159da5d2570946fdcd7da120bf7eb82b840f3
User & Date: drh 2013-01-25 15:59:55
Context
2013-01-25
18:33
Enhance the command-line shell so that adding a non-zero numeric argument to the ".exit" command causes an immediate exit without cleaning up. This can be used (for example) to cause journal files to be left behind. check-in: 8ba951d1 user: drh tags: trunk
15:59
Add btree-page decoding logic to showwal.c. Commands of the form: "showwal $FILE 123bmc" show the content of the btree page in frame 123. "b" means decode the btree. "c" means show cell content. "m" means give a map of the btree page. check-in: 93b159da user: drh tags: trunk
15:31
Further improvements to showwal.c: Reset the checksum after each frame so that only individual checksum failures are shown. And only show failures, not correct checksums. check-in: 4e2bf575 user: drh tags: trunk
Changes
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Changes to tool/showwal.c.

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    }
    if( pCksum->s1!=getInt32(aData+28) ){
      printf("**** cksum-2 mismatch: 0x%08x\n", pCksum->s1);
    }
  }
  free(aData);
}

































































/*






























** Create a description for a single cell.


*/
static int describeCell(unsigned char cType, unsigned char *a, char **pzDesc){





  int i;
  int nDesc = 0;
  int n = 0;
  int leftChild;
  i64 nPayload;
  i64 rowid;

  static char zDesc[100];
  i = 0;
  if( cType<=5 ){
    leftChild = ((a[0]*256 + a[1])*256 + a[2])*256 + a[3];
    a += 4;
    n += 4;
    sprintf(zDesc, "left-child: %d ", leftChild);
    nDesc = strlen(zDesc);
  }
  if( cType!=5 ){
    i = decodeVarint(a, &nPayload);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "sz: %lld ", nPayload);
    nDesc += strlen(&zDesc[nDesc]);



  }
  if( cType==5 || cType==13 ){
    i = decodeVarint(a, &rowid);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "rowid: %lld ", rowid);
    nDesc += strlen(&zDesc[nDesc]);
  }











  *pzDesc = zDesc;
  return n;
}

/*
** Decode a btree page
*/
static void decode_btree_page(unsigned char *a, int pgno, int hdrSize){





  const char *zType = "unknown";
  int nCell;
  int i;
  int iCellPtr;



  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;







  }
  printf("Decode of btree page %d:\n", pgno);
  print_decode_line(a, 0, 1, 0, zType);
  print_decode_line(a, 1, 2, 0, "Offset to first freeblock");
  print_decode_line(a, 3, 2, 0, "Number of cells on this page");
  nCell = a[3]*256 + a[4];
  print_decode_line(a, 5, 2, 0, "Offset to cell content area");
................................................................................
  print_decode_line(a, 7, 1, 0, "Fragmented byte count");
  if( a[0]==2 || a[0]==5 ){
    print_decode_line(a, 8, 4, 0, "Right child");
    iCellPtr = 12;
  }else{
    iCellPtr = 8;
  }










  for(i=0; i<nCell; i++){
    int cofst = iCellPtr + i*2;
    char *zDesc;


    cofst = a[cofst]*256 + a[cofst+1];
    describeCell(a[0], &a[cofst-hdrSize], &zDesc);









    printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
  }






}

int main(int argc, char **argv){
  struct stat sbuf;
  unsigned char zPgSz[2];
  if( argc<2 ){
    fprintf(stderr,"Usage: %s FILENAME ?PAGE? ...\n", argv[0]);
................................................................................
        continue;
      }
      iStart = strtol(argv[i], &zLeft, 0);
      if( zLeft && strcmp(zLeft,"..end")==0 ){
        iEnd = mxFrame;
      }else if( zLeft && zLeft[0]=='.' && zLeft[1]=='.' ){
        iEnd = strtol(&zLeft[2], 0, 0);
#if 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);
        free(a);
        continue;
#endif
      }else{
        iEnd = iStart;
      }
      if( iStart<1 || iEnd<iStart || iEnd>mxFrame ){
        fprintf(stderr,
          "Page argument should be LOWER?..UPPER?.  Range 1 to %d\n",
          mxFrame);







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    }
    if( pCksum->s1!=getInt32(aData+28) ){
      printf("**** cksum-2 mismatch: 0x%08x\n", pCksum->s1);
    }
  }
  free(aData);
}
/*
** Describe cell content.
*/
static int describeContent(
  unsigned char *a,       /* Cell content */
  int nLocal,             /* Bytes in a[] */
  char *zDesc             /* Write description here */
){
  int nDesc = 0;
  int n, i, j;
  i64 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 ){
    n = decodeVarint(a, &x);
    a += n;
    i -= n;
    nLocal -= n;
    zDesc[0] = sep;
    sep = ',';
    nDesc++;
    zDesc++;
    if( x==0 ){
      sprintf(zDesc, "*");     /* NULL is a "*" */
    }else if( x>=1 && x<=6 ){
      v = (signed char)pData[0];
      pData++;
      switch( x ){
        case 6:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
        case 5:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
        case 4:  v = (v<<8) + pData[0];  pData++;
        case 3:  v = (v<<8) + pData[0];  pData++;
        case 2:  v = (v<<8) + pData[0];  pData++;
      }
      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;
      if( (x&1)==0 ){
        sprintf(zDesc, "blob(%d)", size);
      }else{
        sprintf(zDesc, "txt(%d)", size);
      }
      pData += size;
    }
    j = 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;
  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(
  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;
  int n = 0;
  int leftChild;
  i64 nPayload;
  i64 rowid;
  int 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 ){
    i = decodeVarint(a, &nPayload);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "n: %lld ", nPayload);
    nDesc += strlen(&zDesc[nDesc]);
    nLocal = localPayload(nPayload, cType);
  }else{
    nPayload = nLocal = 0;
  }
  if( cType==5 || cType==13 ){
    i = decodeVarint(a, &rowid);
    a += i;
    n += i;
    sprintf(&zDesc[nDesc], "r: %lld ", rowid);
    nDesc += strlen(&zDesc[nDesc]);
  }
  if( nLocal<nPayload ){
    int ovfl;
    unsigned char *b = &a[nLocal];
    ovfl = ((b[0]*256 + b[1])*256 + b[2])*256 + b[3];
    sprintf(&zDesc[nDesc], "ov: %d ", ovfl);
    nDesc += strlen(&zDesc[nDesc]);
    n += 4;
  }
  if( showCellContent && cType!=5 ){
    nDesc += describeContent(a, nLocal, &zDesc[nDesc-1]);
  }
  *pzDesc = zDesc;
  return nLocal+n;
}

/*
** Decode a btree page
*/
static void decode_btree_page(
  unsigned char *a,   /* Content of the btree page to be decoded */
  int pgno,           /* Page number */
  int hdrSize,        /* Size of the page1-header in bytes */
  const char *zArgs   /* Flags to control formatting */
){
  const char *zType = "unknown";
  int nCell;
  int i, j;
  int iCellPtr;
  int showCellContent = 0;
  int showMap = 0;
  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;
    }
    zArgs++;
  }
  printf("Decode of btree page %d:\n", pgno);
  print_decode_line(a, 0, 1, 0, zType);
  print_decode_line(a, 1, 2, 0, "Offset to first freeblock");
  print_decode_line(a, 3, 2, 0, "Number of cells on this page");
  nCell = a[3]*256 + a[4];
  print_decode_line(a, 5, 2, 0, "Offset to cell content area");
................................................................................
  print_decode_line(a, 7, 1, 0, "Fragmented byte count");
  if( a[0]==2 || a[0]==5 ){
    print_decode_line(a, 8, 4, 0, "Right child");
    iCellPtr = 12;
  }else{
    iCellPtr = 8;
  }
  if( 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;

    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);
      zMap[cofst] = '[';
      zMap[cofst+n-1] = ']';
      sprintf(zBuf, "%d", i);
      j = strlen(zBuf);
      if( j<=n-2 ) memcpy(&zMap[cofst+1], zBuf, j);
    }
    printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
  }
  if( showMap ){
    for(i=0; i<pagesize; i+=64){
      printf(" %03x: %.64s\n", i, &zMap[i]);
    }
    free(zMap);
  }  
}

int main(int argc, char **argv){
  struct stat sbuf;
  unsigned char zPgSz[2];
  if( argc<2 ){
    fprintf(stderr,"Usage: %s FILENAME ?PAGE? ...\n", argv[0]);
................................................................................
        continue;
      }
      iStart = strtol(argv[i], &zLeft, 0);
      if( zLeft && strcmp(zLeft,"..end")==0 ){
        iEnd = mxFrame;
      }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 ){
          hdrSize = 100;
          ofst = hdrSize = 100;
          nByte = pagesize-100;
        }else{
          hdrSize = 0;
          ofst = (iStart-1)*pagesize;
          nByte = pagesize;
        }
        ofst = 32 + hdrSize + (iStart-1)*(pagesize+24) + 24;
        a = getContent(ofst, nByte);
        decode_btree_page(a, iStart, hdrSize, zLeft+1);
        free(a);
        continue;

      }else{
        iEnd = iStart;
      }
      if( iStart<1 || iEnd<iStart || iEnd>mxFrame ){
        fprintf(stderr,
          "Page argument should be LOWER?..UPPER?.  Range 1 to %d\n",
          mxFrame);