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 fileSize = 0;
  16 static unsigned cksumNonce = 0;
  17
  18 /* Report a memory allocation error */
  19 static void out_of_memory(void){
  20   fprintf(stderr,"Out of memory...\n");
  21   exit(1);
  22 }
  23
  24 /*
  25 ** Read N bytes of memory starting at iOfst into space obtained
  26 ** from malloc().
  27 */
  28 static unsigned char *read_content(int N, int iOfst){
  29   int got;
  30   unsigned char *pBuf = malloc(N);
  31   if( pBuf==0 ) out_of_memory();
  32   fseek(db, iOfst, SEEK_SET);
  33   got = (int)fread(pBuf, 1, N, db);
  34   if( got<0 ){
  35     fprintf(stderr, "I/O error reading %d bytes from %d\n", N, iOfst);
  36     memset(pBuf, 0, N);
  37   }else if( got<N ){
  38     fprintf(stderr, "Short read: got only %d of %d bytes from %d\n",
  39                      got, N, iOfst);
  40     memset(&pBuf[got], 0, N-got);
  41   }
  42   return pBuf;
  43 }
  44
  45 /* Print a line of decode output showing a 4-byte integer.
  46 */
  47 static unsigned print_decode_line(
  48   const unsigned char *aData,  /* Content being decoded */
  49   int ofst, int nByte,         /* Start and size of decode */
  50   const char *zMsg             /* Message to append */
  51 ){
  52   int i, j;
  53   unsigned val = aData[ofst];
  54   char zBuf[100];
  55   sprintf(zBuf, " %05x: %02x", ofst, aData[ofst]);
  56   i = (int)strlen(zBuf);
  57   for(j=1; j<4; j++){
  58     if( j>=nByte ){
  59       sprintf(&zBuf[i], "   ");
  60     }else{
  61       sprintf(&zBuf[i], " %02x", aData[ofst+j]);
  62       val = val*256 + aData[ofst+j];
  63     }
  64     i += (int)strlen(&zBuf[i]);
  65   }
  66   sprintf(&zBuf[i], "   %10u", val);
  67   printf("%s  %s\n", zBuf, zMsg);
  68   return val;
  69 }
  70
  71 /*
  72 ** Read and print a journal header.  Store key information (page size, etc)
  73 ** in global variables.
  74 */
  75 static unsigned decode_journal_header(int iOfst){
  76   unsigned char *pHdr = read_content(64, iOfst);
  77   unsigned nPage;
  78   printf("Header at offset %d:\n", iOfst);
  79   print_decode_line(pHdr, 0, 4, "Header part 1 (3654616569)");
  80   print_decode_line(pHdr, 4, 4, "Header part 2 (547447767)");
  81   nPage =
  82   print_decode_line(pHdr, 8, 4, "page count");
  83   cksumNonce =
  84   print_decode_line(pHdr, 12, 4, "chksum nonce");
  85   print_decode_line(pHdr, 16, 4, "initial database size in pages");
  86   sectorSize =
  87   print_decode_line(pHdr, 20, 4, "sector size");
  88   pageSize =
  89   print_decode_line(pHdr, 24, 4, "page size");
  90   print_decode_line(pHdr, 28, 4, "zero");
  91   print_decode_line(pHdr, 32, 4, "zero");
  92   print_decode_line(pHdr, 36, 4, "zero");
  93   print_decode_line(pHdr, 40, 4, "zero");
  94   free(pHdr);
  95   return nPage;
  96 }
  97
  98 static void print_page(int iOfst){
  99   unsigned char *aData;
 100   char zTitle[50];
 101   aData = read_content(pageSize+8, iOfst);
 102   sprintf(zTitle, "page number for page at offset %d", iOfst);
 103   print_decode_line(aData-iOfst, iOfst, 4, zTitle);
 104   free(aData);
 105 }
 106
 107 int main(int argc, char **argv){
 108   int nPage, cnt;
 109   int iOfst;
 110   if( argc!=2 ){
 111     fprintf(stderr,"Usage: %s FILENAME\n", argv[0]);
 112     exit(1);
 113   }
 114   db = fopen(argv[1], "rb");
 115   if( db==0 ){
 116     fprintf(stderr,"%s: can't open %s\n", argv[0], argv[1]);
 117     exit(1);
 118   }
 119   fseek(db, 0, SEEK_END);
 120   fileSize = ftell(db);
 121   printf("journal file size: %d bytes\n", fileSize);
 122   fseek(db, 0, SEEK_SET);
 123   iOfst = 0;
 124   while( iOfst<fileSize ){
 125     cnt = nPage = (int)decode_journal_header(iOfst);
 126     if( cnt==0 ){
 127       cnt = (fileSize - sectorSize)/(pageSize+8);
 128     }
 129     iOfst += sectorSize;
 130     while( cnt && iOfst<fileSize ){
 131       print_page(iOfst);
 132       iOfst += pageSize+8;
 133     }
 134     iOfst = (iOfst/sectorSize + 1)*sectorSize;
 135   }
 136   fclose(db);
 137   return 0;
 138 }