mdw@git.distorted.org.uk Git - dvdrip/blob - chkdvdimg.c

   1 #include "lib.h"
   2
   3 static int status = 0;
   4 static unsigned flags = 0;
   5 #define F_FIX 1u
   6
   7 static void vgripe_syserr(int st, int err, const char *fmt, va_list ap)
   8   { vmoan_syserr(err, fmt, ap); if (st > status) status = st; }
   9 static void vgripe(int st, const char *fmt, va_list ap)
  10   { vgripe_syserr(st, 0, fmt, ap); }
  11 PRINTF_LIKE(3, 4)
  12   static void gripe_syserr(int st, int err, const char *fmt, ...)
  13 {
  14   va_list ap;
  15   va_start(ap, fmt); vgripe_syserr(st, err, fmt, ap); va_end(ap);
  16 }
  17 PRINTF_LIKE(2, 3) static void gripe(int st, const char *fmt, ...)
  18   { va_list ap; va_start(ap, fmt); vgripe(st, fmt, ap); va_end(ap); }
  19
  20 static int carefully_read(int fd, off_t off,
  21                           void *p, size_t sz, const char *file)
  22 {
  23   ssize_t n;
  24   char *q = p;
  25
  26   if (lseek(fd, off, SEEK_SET) < 0)
  27     { gripe_syserr(2, errno, "failed to seek in `%s'", file); return (-1); }
  28
  29   while (sz) {
  30     n = read(fd, q, sz);
  31     if (n < 0)
  32       { gripe_syserr(2, errno, "failed to read `%s'", file); return (-1); }
  33     else if (!n)
  34       { gripe(2, "unexpected end-of-file reading `%s'", file); return (-1); }
  35     q += n; sz -= n;
  36   }
  37   return (0);
  38 }
  39
  40 typedef uint_least32_t u32;
  41 #define Pu32 PRIuLEAST32
  42
  43 static u32 load32(const unsigned char *p)
  44 {
  45   return (((u32)p[0] <<  0) | ((u32)p[1] <<  8) |
  46           ((u32)p[2] << 16) | ((u32)p[3] << 24));
  47 }
  48
  49 #define CAHF_GRIPE 1u
  50 #define CAHF_FULL 1u
  51 static int check_anchor_header(const unsigned char  *b, secaddr addr,
  52                                unsigned f, const char *file)
  53 {
  54   unsigned i, t;
  55   secaddr n;
  56
  57   if (b[0] != 2) {
  58     if (f&CAHF_GRIPE)
  59       gripe(1, "anchor descriptor not found at `%s' sector %"PRIuSEC"",
  60             file, addr);
  61     return (-1);
  62   }
  63
  64   for (i = 0, t = 0; i < 16; i++) if (i != 4) t += b[i];
  65   t %= 256;
  66   if (b[4] != t) {
  67     if (f&CAHF_GRIPE)
  68       gripe(1, "bad anchor descriptor header checksum (%u /= %u) "
  69             "at `%s' sector %"PRIuSEC"", (unsigned)b[4], t, file, addr);
  70     return (-1);
  71   }
  72
  73   if (f&CAHF_FULL) {
  74     n = load32(b + 12);
  75     if (n != addr) {
  76       if (f&CAHF_GRIPE)
  77         gripe(1, "bad sector number in anchor descriptor "
  78               "(%"PRIuSEC" /= %"PRIuSEC") in `%s'",
  79               n, addr, file);
  80       return (-1);
  81     }
  82   }
  83
  84   return (0);
  85 }
  86
  87 static int all_zero_p(const unsigned char *p, size_t sz)
  88 {
  89   while (sz) {
  90     if (*p) return (0);
  91     p++; sz--;
  92   }
  93   return (1);
  94 }
  95
  96 static void check_img(const char *file)
  97 {
  98   int fd = -1;
  99   unsigned char b[SECTORSZ], bb[SECTORSZ];
 100   off_t volsz;
 101   int blksz;
 102   secaddr end;
 103   unsigned i, j;
 104
 105   fd = open(file, (flags&F_FIX) ? O_RDWR : O_RDONLY);
 106   if (fd < 0)
 107     { gripe_syserr(2, errno, "failed to open `%s'", file); goto end; }
 108   blksz = SECTORSZ; volsz = device_size(fd, file, &blksz);
 109   if (SECTORSZ != 2048)
 110     { gripe(2, "device sector size %d /= 2048", blksz); goto end; }
 111   if (volsz%SECTORSZ) {
 112     gripe(2, "bad length for `%s' -- not whole number of sectors", file);
 113     goto end;
 114   }
 115   end = volsz/SECTORSZ;
 116
 117   if (carefully_read(fd, 256*SECTORSZ, b, SECTORSZ, file) ||
 118       check_anchor_header(b, 256, CAHF_GRIPE | CAHF_FULL, file))
 119     goto end;
 120
 121   for (i = 1; i < 32768; i++) {
 122     if (carefully_read(fd, (off_t)(end - i)*SECTORSZ, bb, SECTORSZ, file))
 123       goto end;
 124     if (bb[0] || !all_zero_p(bb, SECTORSZ)) goto nonzero;
 125   }
 126   gripe(1, "too many trailing zero sectors: "
 127         "couldn't find backup anchor descriptor in `%s'", file);
 128   goto end;
 129 nonzero:
 130   j = i;
 131   for (;;) {
 132     if (bb[0] == 2 && !check_anchor_header(bb, end - j, 0, file))
 133       break;
 134     j++;
 135     if (j > i + 256) {
 136       gripe(1, "failed to find backup anchor descriptor in `%s'", file);
 137       goto end;
 138     }
 139     if (carefully_read(fd, (off_t)(end - j)*SECTORSZ, bb, SECTORSZ, file))
 140       goto end;
 141   }
 142   if (j > i) {
 143     gripe(1, "found backup anchor descriptor at sector %"PRIuSEC" "
 144           " = %"PRIuSEC" from end, = %"PRIuSEC" from trailing zeros",
 145           end - j, j, j - i + 1);
 146     i = j;
 147   }
 148
 149   if (check_anchor_header(bb, end - i, CAHF_GRIPE | CAHF_FULL, file))
 150     goto end;
 151
 152   if (MEMCMP(b + 16, != , bb + 16, SECTORSZ - 16)) {
 153     gripe(1, "backup anchor descriptor in sector %"PRIuSEC" "
 154           "doesn't match primary in sector 256 of `%s'",
 155           end - i, file);
 156     goto end;
 157   }
 158
 159   if (i > 1) {
 160     if (!(flags&F_FIX))
 161       gripe(1, "%u trailing zero sectors in `%s'", i - 1, file);
 162     else {
 163       if (ftruncate(fd, (off_t)(end - i + 1)*SECTORSZ))
 164         gripe_syserr(2, errno,
 165                      "failed to truncate `%s' to %"PRIuSEC" sectors",
 166                      file, end - i + 1);
 167       else
 168         moan("removed %u trailing zero sectors from `%s'", i - 1, file);
 169     }
 170   }
 171
 172 end:
 173   if (fd != -1) close(fd);
 174 }
 175
 176 static void usage(FILE *fp)
 177   { fprintf(fp, "usage: %s [-x] IMG ...\n", prog); }
 178
 179 int main(int argc, char *argv[])
 180 {
 181   int i, opt;
 182   unsigned f = 0;
 183 #define f_bogus 1u
 184
 185   set_prog(argv[0]);
 186   for (;;) {
 187     opt = getopt(argc, argv, "hx"); if (opt < 0) break;
 188     switch (opt) {
 189       case 'h': usage(stdout); exit(0);
 190       case 'x': flags |= F_FIX; break;
 191       default: f |= f_bogus; break;
 192     }
 193   }
 194   if (optind >= argc) f |= f_bogus;
 195   if (f&f_bogus) { usage(stderr); exit(2); }
 196
 197   for (i = optind; i < argc; i++) check_img(argv[i]);
 198   return (status);
 199 }