tool/showjournal.c

   1 /*
   2 ** A utility for printing an SQLite database journal.
   3 */
   4 #include <stdio.h>
   5 #include <ctype.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8
   9 /*
  10 ** state information
  11 */
  12 static int pageSize = 1024;
  13 static int sectorSize = 512;
  14 static FILE *db = 0;
  15 static int showPageContent = 0;
  16 static int fileSize = 0;
  17 static unsigned cksumNonce = 0;
  18
  19 /* Report a memory allocation error */
  20 static void out_of_memory(void){
  21   fprintf(stderr,"Out of memory...\n");
  22   exit(1);
  23 }
  24
  25 /*
  26 ** Read N bytes of memory starting at iOfst into space obtained
  27 ** from malloc().
  28 */
  29 static char *read_content(int N, int iOfst){
  30   int got;
  31   char *pBuf = malloc(N);
  32   if( pBuf==0 ) out_of_memory();
  33   fseek(db, iOfst, SEEK_SET);
  34   got = fread(pBuf, 1, N, db);
  35   if( got<0 ){
  36     fprintf(stderr, "I/O error reading %d bytes from %d\n", N, iOfst);
  37     memset(pBuf, 0, N);
  38   }else if( got<N ){
  39     fprintf(stderr, "Short read: got only %d of %d bytes from %d\n",
  40                      got, N, iOfst);
  41     memset(&pBuf[got], 0, N-got);
  42   }
  43   return pBuf;
  44 }
  45
  46 /* Print a line of decode output showing a 4-byte integer.
  47 */
  48 static unsigned print_decode_line(
  49   unsigned char *aData,      /* Content being decoded */
  50   int ofst, int nByte,       /* Start and size of decode */
  51   const char *zMsg           /* Message to append */
  52 ){
  53   int i, j;
  54   unsigned val = aData[ofst];
  55   char zBuf[100];
  56   sprintf(zBuf, " %03x: %02x", ofst, aData[ofst]);
  57   i = strlen(zBuf);
  58   for(j=1; j<4; j++){
  59     if( j>=nByte ){
  60       sprintf(&zBuf[i], "   ");
  61     }else{
  62       sprintf(&zBuf[i], " %02x", aData[ofst+j]);
  63       val = val*256 + aData[ofst+j];
  64     }
  65     i += strlen(&zBuf[i]);
  66   }
  67   sprintf(&zBuf[i], "   %10u", val);
  68   printf("%s  %s\n", zBuf, zMsg);
  69   return val;
  70 }
  71
  72 /*
  73 ** Read and print a journal header.  Store key information (page size, etc)
  74 ** in global variables.
  75 */
  76 static unsigned decode_journal_header(int iOfst){
  77   char *pHdr = read_content(64, iOfst);
  78   unsigned nPage;
  79   printf("Header at offset %d:\n", iOfst);
  80   print_decode_line(pHdr, 0, 4, "Header part 1 (3654616569)");
  81   print_decode_line(pHdr, 4, 4, "Header part 2 (547447767)");
  82   nPage =
  83   print_decode_line(pHdr, 8, 4, "page count");
  84   cksumNonce =
  85   print_decode_line(pHdr, 12, 4, "chksum nonce");
  86   print_decode_line(pHdr, 16, 4, "initial database size in pages");
  87   sectorSize =
  88   print_decode_line(pHdr, 20, 4, "sector size");
  89   pageSize =
  90   print_decode_line(pHdr, 24, 4, "page size");
  91   print_decode_line(pHdr, 28, 4, "zero");
  92   print_decode_line(pHdr, 32, 4, "zero");
  93   print_decode_line(pHdr, 36, 4, "zero");
  94   print_decode_line(pHdr, 40, 4, "zero");
  95   free(pHdr);
  96   return nPage;
  97 }
  98
  99 static void print_page(int iOfst){
 100   unsigned char *aData;
 101   char zTitle[50];
 102   aData = read_content(pageSize+8, iOfst);
 103   sprintf(zTitle, "page number for page at offset %d", iOfst);
 104   print_decode_line(aData, 0, 4, zTitle);
 105   free(aData);
 106 }
 107
 108 int main(int argc, char **argv){
 109   int rc;
 110   int nPage, cnt;
 111   int iOfst;
 112   if( argc!=2 ){
 113     fprintf(stderr,"Usage: %s FILENAME\n", argv[0]);
 114     exit(1);
 115   }
 116   db = fopen(argv[1], "rb");
 117   if( db==0 ){
 118     fprintf(stderr,"%s: can't open %s\n", argv[0], argv[1]);
 119     exit(1);
 120   }
 121   fseek(db, 0, SEEK_END);
 122   fileSize = ftell(db);
 123   printf("journal file size: %d bytes\n", fileSize);
 124   fseek(db, 0, SEEK_SET);
 125   iOfst = 0;
 126   while( iOfst<fileSize ){
 127     cnt = nPage = (int)decode_journal_header(iOfst);
 128     if( cnt==0 ){
 129       cnt = (fileSize - sectorSize)/(pageSize+8);
 130     }
 131     iOfst += sectorSize;
 132     while( cnt && iOfst<fileSize ){
 133       print_page(iOfst);
 134       iOfst += pageSize+8;
 135     }
 136     iOfst = (iOfst/sectorSize + 1)*sectorSize;
 137   }
 138   fclose(db);
 139 }