bdiff.c

binary diff tool. scans input for matching patterns.

/* (c) 2008 Petter Wahlman */
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>

void print_usage(void)
{
   fprintf(stderr, "usage: bdiff <file1> <file2> <offset1> <offset2> <val1> <val2>\n");
   exit(1);
}

int main(int argc, char **argv)
{
   int fd[2];
   unsigned long val[2];
   off_t offset[2];
   int ret = 1;

   if (argc != 7)
      print_usage();

   fd[0] = open(argv[1], O_RDONLY);
   fd[1] = open(argv[2], O_RDONLY);

   if ((-1 == fd[0]) || (-1 == fd[1]) ) {
      fprintf(stderr, "can't open %s\n", fd[0] == -1 ? argv[1] : argv[2]);
      goto out;
   }

   offset[0] = strtoul(argv[3], NULL, 0);
   offset[1] = strtoul(argv[4], NULL, 0);

   val[0] = strtoul(argv[5], NULL, 0);
   val[1] = strtoul(argv[6], NULL, 0);

   printf("bdiff:\n"
          "   file 0: %s\n"
          "   file 1: %s\n"
          " offset 0: 0x%08lx\n"
          " offset 1: 0x%08lx\n"
          "   byte 0: 0x%x\n"
          "   byte 1: 0x%x\n",
            argv[1], argv[2],
            offset[0], offset[1],
            (unsigned char)val[0], (unsigned char)val[1]);

   if(-1 == lseek(fd[0], offset[0], SEEK_SET)) {
      fprintf(stderr, "unable to seek to offset: 0x%08lx in %s\n", offset[0], argv[1]);
      goto out;
   }

   if(-1 == lseek(fd[1], offset[1], SEEK_SET)) {
      fprintf(stderr, "unable to seek to offset: 0x%08lx in %s\n", offset[1], argv[2]);
      goto out;
   }

   do {
      unsigned char c[2];
      int rc[2];

      rc[0] = read(fd[0], &c[0], 1);
      rc[1] = read(fd[1], &c[1], 1);

      if ((-1 == rc[0]) || (-1 == rc[1])) {
         fprintf(stderr, "%s %s\n", strerror(errno), rc[0] ? argv[1] : argv[2]);
         goto out;
      }

      if (!(rc[0] || rc[1]))
         break;

      if ((val[0] == c[0]) && (val[1] == c[1]))
         printf("match at both offsets: 0x%08lx - 0x%08lx\n", offset[0], offset[1]); 

      offset[0]++;
      offset[1]++;

   } while(1);

   ret = 0;
out:
   close(fd[0]);
   close(fd[1]);

   return ret;
}