dromfs/dromfs.c

   1 #include <stdio.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <sys/mman.h>
   5 #include <fcntl.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9 #include <stdint.h>
  10 #include <arpa/inet.h>
  11
  12 struct romfs_sb {
  13         char name[9];
  14         uint32_t size;
  15         uint32_t checksum;
  16         char vname[17];
  17 };
  18
  19 static void usage(void)
  20 {
  21         printf("Usage: rromfs < device >\n");
  22 }
  23
  24 static struct romfs_sb *get_romfs_sb(const char *path)
  25 {
  26         int fd;
  27         uint8_t *p;
  28         struct romfs_sb *sb;
  29         const size_t sb_length = 16;
  30
  31         fd = open(path, O_RDONLY);
  32         if (fd < 0) {
  33                 perror("open()");
  34                 exit(1);
  35         }
  36
  37         sb = malloc(sizeof(struct romfs_sb));
  38         if (!sb) {
  39                 perror("malloc()");
  40                 goto err_malloc;
  41         }
  42         memset(sb, 0, sizeof(struct romfs_sb));
  43
  44         p = mmap(NULL, sb_length, PROT_READ, MAP_PRIVATE, fd, (off_t) 0);
  45         if (!p) {
  46                 perror("mmap()");
  47                 goto err_mmap;
  48         }
  49
  50         /* File-system name */
  51         memcpy(&sb->name, p, (size_t) 8);
  52
  53         /* Volume name */
  54         memcpy(&sb->vname, (char *) p+16, (size_t) 16);
  55
  56         /*
  57          * FIXME: Is there a nicer way to read big
  58          * endian values?
  59          */
  60
  61         /* size */
  62         memcpy(&sb->size, (uint8_t *) p+8, (size_t) 4);
  63         sb->size = ntohl(sb->size);
  64
  65         /* checksum */
  66         memcpy(&sb->checksum, (uint8_t *) p+12, (size_t) 4);
  67         sb->checksum = ntohl(sb->checksum);
  68
  69         munmap(p, sb_length);
  70         close(fd);
  71         return sb;
  72
  73 err_mmap:
  74         free(sb);
  75 err_malloc:
  76         close(fd);
  77         exit(1);
  78 }
  79
  80 int main(int argc, char *argv[])
  81 {
  82         struct romfs_sb *sb;
  83
  84         if (argc != 2) {
  85                 usage();
  86                 exit(1);
  87         }
  88
  89         sb = get_romfs_sb(argv[1]);
  90         if (!sb)
  91                 exit(1);
  92
  93         /* Super-block information */
  94         printf("sig: %s\n", sb->name);
  95         printf("size: %d\n", sb->size);
  96         printf("checksum: %d\n", sb->checksum);
  97         printf("Volume name: %s\n", sb->vname);
  98
  99         free(sb);
 100         return 0;
 101 }