tool/showshm.c

   1 /*
   2 ** A utility for printing content from the wal-index or "shm" file.
   3 */
   4 #include <stdio.h>
   5 #include <ctype.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9 #include <assert.h>
  10
  11 #define ISDIGIT(X)  isdigit((unsigned char)(X))
  12 #define ISPRINT(X)  isprint((unsigned char)(X))
  13
  14 #if !defined(_MSC_VER)
  15 #include <unistd.h>
  16 #include <sys/types.h>
  17 #else
  18 #include <io.h>
  19 #endif
  20
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 static int fd = -1;             /* The open SHM file */
  25
  26 /* Report an out-of-memory error and die.
  27 */
  28 static void out_of_memory(void){
  29   fprintf(stderr,"Out of memory...\n");
  30   exit(1);
  31 }
  32
  33 /*
  34 ** Read content from the file.
  35 **
  36 ** Space to hold the content is obtained from malloc() and needs to be
  37 ** freed by the caller.
  38 */
  39 static unsigned char *getContent(int ofst, int nByte){
  40   unsigned char *aData;
  41   aData = malloc(nByte);
  42   if( aData==0 ) out_of_memory();
  43   lseek(fd, ofst, SEEK_SET);
  44   read(fd, aData, nByte);
  45   return aData;
  46 }
  47
  48 /*
  49 ** Flags values
  50 */
  51 #define FG_HEX     1    /* Show as hex */
  52 #define FG_NBO     2    /* Native byte order */
  53 #define FG_PGSZ    4    /* Show as page-size */
  54
  55 /* Print a line of decode output showing a 4-byte integer.
  56 */
  57 static void print_decode_line(
  58   unsigned char *aData,      /* Content being decoded */
  59   int ofst, int nByte,       /* Start and size of decode */
  60   unsigned flg,              /* Display flags */
  61   const char *zMsg           /* Message to append */
  62 ){
  63   int i, j;
  64   int val = aData[ofst];
  65   char zBuf[100];
  66   sprintf(zBuf, " %03x: %02x", ofst, aData[ofst]);
  67   i = (int)strlen(zBuf);
  68   for(j=1; j<4; j++){
  69     if( j>=nByte ){
  70       sprintf(&zBuf[i], "   ");
  71     }else{
  72       sprintf(&zBuf[i], " %02x", aData[ofst+j]);
  73       val = val*256 + aData[ofst+j];
  74     }
  75     i += (int)strlen(&zBuf[i]);
  76   }
  77   if( nByte==8 ){
  78     for(j=4; j<8; j++){
  79       sprintf(&zBuf[i], " %02x", aData[ofst+j]);
  80       i += (int)strlen(&zBuf[i]);
  81     }
  82   }
  83   if( flg & FG_NBO ){
  84     assert( nByte==4 );
  85     memcpy(&val, aData+ofst, 4);
  86   }
  87   sprintf(&zBuf[i], "            ");
  88   i += 12;
  89   if( flg & FG_PGSZ ){
  90     unsigned short sz;
  91     memcpy(&sz, aData+ofst, 2);
  92     sprintf(&zBuf[i], "   %9d", sz==1 ? 65536 : sz);
  93   }else if( flg & FG_HEX ){
  94     sprintf(&zBuf[i], "  0x%08x", val);
  95   }else if( nByte<8 ){
  96     sprintf(&zBuf[i], "   %9d", val);
  97   }
  98   printf("%s  %s\n", zBuf, zMsg);
  99 }
 100
 101 /*
 102 ** Print an instance of the WalIndexHdr object.  ix is either 0 or 1
 103 ** to select which header to print.
 104 */
 105 static void print_index_hdr(unsigned char *aData, int ix){
 106   int i;
 107   assert( ix==0 || ix==1 );
 108   i = ix ? 48 : 0;
 109   print_decode_line(aData, 0+i, 4, FG_NBO,  "Wal-index version");
 110   print_decode_line(aData, 4+i, 4, 0,       "unused padding");
 111   print_decode_line(aData, 8+i, 4, FG_NBO,  "transaction counter");
 112   print_decode_line(aData,12+i, 1, 0,       "1 when initialized");
 113   print_decode_line(aData,13+i, 1, 0,       "true if WAL cksums are bigendian");
 114   print_decode_line(aData,14+i, 2, FG_PGSZ, "database page size");
 115   print_decode_line(aData,16+i, 4, FG_NBO,  "mxFrame");
 116   print_decode_line(aData,20+i, 4, FG_NBO,  "Size of database in pages");
 117   print_decode_line(aData,24+i, 8, 0, "Cksum of last frame in -wal");
 118   print_decode_line(aData,32+i, 8, 0,  "Salt values from the -wal");
 119   print_decode_line(aData,40+i, 8, 0,  "Cksum over all prior fields");
 120 }
 121
 122 /*
 123 ** Print the WalCkptInfo object
 124 */
 125 static void print_ckpt_info(unsigned char *aData){
 126   const int i = 96;
 127   int j;
 128   print_decode_line(aData, 0+i, 4, FG_NBO,  "nBackfill");
 129   for(j=0; j<5; j++){
 130     char zLabel[100];
 131     sprintf(zLabel, "aReadMark[%d]", j);
 132     print_decode_line(aData, 4*j+4+i, 4, FG_NBO, zLabel);
 133   }
 134   print_decode_line(aData,24+i, 8, 0,       "aLock");
 135   print_decode_line(aData,32+i, 4, FG_NBO,  "nBackfillAttempted");
 136   print_decode_line(aData,36+i, 4, FG_NBO,  "notUsed0");
 137 }
 138
 139
 140 int main(int argc, char **argv){
 141   unsigned char *aData;
 142   if( argc<2 ){
 143     fprintf(stderr,"Usage: %s FILENAME\n", argv[0]);
 144     exit(1);
 145   }
 146   fd = open(argv[1], O_RDONLY);
 147   if( fd<0 ){
 148     fprintf(stderr,"%s: can't open %s\n", argv[0], argv[1]);
 149     exit(1);
 150   }
 151   aData = getContent(0, 136);
 152   print_index_hdr(aData, 0);
 153   print_index_hdr(aData, 1);
 154   print_ckpt_info(aData);
 155   free(aData);
 156   close(fd);
 157   return 0;
 158 }