che.c

program for changing endianness of firmware dumps

/*
 * (c) petter wahlman, [e-mail]
 *
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <che.h>


void print_usage(void)
{
   printf("usage: che [OPTIONS] <source> <dest>\n"
          "           --help      this info\n"
          "           --type #num where num is one of the following:\n"
          "                  0    dword: 0,1,2,3\n"
          "                  0    dword: 1,0,3,2\n"
          "                  0    dword: 2,3,0,1\n"
          "                  0    dword: 3,2,1,0\n"
   );
   exit(1);
}

int main(int argc, char **argv)
{
   char *source, *dest;
   char *buf;
   struct stat st;
   unsigned int i;
   size_t nr;
   u32 type;
   int fd, fdd;
   int rc = 1;

   if (argc < 2) {
      print_usage();
      return rc;
   }

   while (1) {
      u32 c;
      s32 option_index = 0;
      static struct option long_options[] = { 
         { "help",    0, 0, 'h' },  
         { "type",    1, 0, 't' },  
         { NULL,      0, 0,  0  }
      };  

      c = getopt_long(argc, argv, "ht:", long_options, &option_index);
      if (-1 == c)
         break;

      switch (c) {
         case 'h':
            print_usage();
            break;

         case 't':
            type = strtoul(optarg, NULL, 0x0);
            break;

         default:
            print_usage();
            break;
       }
   }

   source = argv[optind++];
   fd = open(source, O_RDONLY);
   if (-1 == fd) {
      perror(source);
      return rc;
   }

   fdd = fileno(stdout);
   dest = argv[optind++];
   if (dest) {
      fdd = open(dest, O_WRONLY | O_CREAT, 0644);
      if (-1 == fdd) {
         perror(dest);
         close(fd);
         return rc;
      }
   }

   fstat(fd, &st);
   buf = malloc(st.st_size);
   if (!buf) {
      perror("malloc");
      return rc;
   }

   if (isatty(1)) {
      printf("source: %s\n", source);
      printf("dest:   %s\n", dest ? dest : "stdout");
      printf("size:   0x%08lx\n", st.st_size);
   }

   nr = read(fd, buf, st.st_size);
   if (nr != st.st_size) {
      fprintf(stderr, "error, incorrect number of bytes read: %s\n", strerror(errno));
      return rc;
   }

   for (i = 0; i < nr; i+=4) {
      unsigned int val;
      unsigned char b[4];

      val = *(unsigned int *) &buf[i];
      switch(type) {
         case 0:
            b[0] = val & 0xff;
            b[1] = (val >>  8) & 0xff;
            b[2] = (val >> 16) & 0xff;
            b[3] = (val >> 24) & 0xff;
            break;
         case 1:
            b[1] = val & 0xff;
            b[0] = (val >>  8) & 0xff;
            b[3] = (val >> 16) & 0xff;
            b[2] = (val >> 24) & 0xff;
            break;
         case 2:
            b[2] = val & 0xff;
            b[3] = (val >>  8) & 0xff;
            b[0] = (val >> 16) & 0xff;
            b[1] = (val >> 24) & 0xff;
            break;
         case 3:
            b[3] = val & 0xff;
            b[2] = (val >>  8) & 0xff;
            b[1] = (val >> 16) & 0xff;
            b[0] = (val >> 24) & 0xff;
            break;

      }
      memcpy(&buf[i], b, sizeof(b));
   }
   write(fdd, buf, st.st_size);

   free(buf);
   close(fd);
   close(fdd);
   return 0;
}