chkdvdimg.c: Name the file when reporting too many trailing zeros.

[dvdrip] / chkdvdimg.c

#include "lib.h"

static int status = 0;
static unsigned flags = 0;
#define F_FIX 1u

static void vgripe_syserr(int st, int err, const char *fmt, va_list ap)
  { vmoan_syserr(err, fmt, ap); if (st > status) status = st; }
static void vgripe(int st, const char *fmt, va_list ap)
  { vgripe_syserr(st, 0, fmt, ap); }
PRINTF_LIKE(3, 4)
  static void gripe_syserr(int st, int err, const char *fmt, ...)
{
  va_list ap;
  va_start(ap, fmt); vgripe_syserr(st, err, fmt, ap); va_end(ap);
}
PRINTF_LIKE(2, 3) static void gripe(int st, const char *fmt, ...)
  { va_list ap; va_start(ap, fmt); vgripe(st, fmt, ap); va_end(ap); }

static int carefully_read(int fd, off_t off,
			  void *p, size_t sz, const char *file)
{
  ssize_t n;
  char *q = p;

  if (lseek(fd, off, SEEK_SET) < 0)
    { gripe_syserr(2, errno, "failed to seek in `%s'", file); return (-1); }

  while (sz) {
    n = read(fd, q, sz);
    if (n < 0)
      { gripe_syserr(2, errno, "failed to read `%s'", file); return (-1); }
    else if (!n)
      { gripe(2, "unexpected end-of-file reading `%s'", file); return (-1); }
    q += n; sz -= n;
  }
  return (0);
}

typedef uint_least32_t u32;
#define Pu32 PRIuLEAST32

static u32 load32(const unsigned char *p)
{
  return (((u32)p[0] <<  0) | ((u32)p[1] <<  8) |
	  ((u32)p[2] << 16) | ((u32)p[3] << 24));
}

#define CAHF_GRIPE 1u
#define CAHF_FULL 1u
static int check_anchor_header(const unsigned char  *b, secaddr addr,
			       unsigned f, const char *file)
{
  unsigned i, t;
  secaddr n;

  if (b[0] != 2) {
    if (f&CAHF_GRIPE)
      gripe(1, "anchor descriptor not found at `%s' sector %"PRIuSEC"",
	    file, addr);
    return (-1);
  }

  for (i = 0, t = 0; i < 16; i++) if (i != 4) t += b[i];
  t %= 256;
  if (b[4] != t) {
    if (f&CAHF_GRIPE)
      gripe(1, "bad anchor descriptor header checksum (%u /= %u) "
	    "at `%s' sector %"PRIuSEC"", (unsigned)b[4], t, file, addr);
    return (-1);
  }

  if (f&CAHF_FULL) {
    n = load32(b + 12);
    if (n != addr) {
      if (f&CAHF_GRIPE)
	gripe(1, "bad sector number in anchor descriptor "
	      "(%"PRIuSEC" /= %"PRIuSEC") in `%s'",
	      n, addr, file);
      return (-1);
    }
  }

  return (0);
}

static int all_zero_p(const unsigned char *p, size_t sz)
{
  while (sz) {
    if (*p) return (0);
    p++; sz--;
  }
  return (1);
}

static void check_img(const char *file)
{
  int fd = -1;
  unsigned char b[SECTORSZ], bb[SECTORSZ];
  off_t volsz;
  int blksz;
  secaddr end;
  unsigned i, j;

  fd = open(file, (flags&F_FIX) ? O_RDWR : O_RDONLY);
  if (fd < 0)
    { gripe_syserr(2, errno, "failed to open `%s'", file); goto end; }
  blksz = SECTORSZ; volsz = device_size(fd, file, &blksz);
  if (SECTORSZ != 2048)
    { gripe(2, "device sector size %d /= 2048", blksz); goto end; }
  if (volsz%SECTORSZ) {
    gripe(2, "bad length for `%s' -- not whole number of sectors", file);
    goto end;
  }
  end = volsz/SECTORSZ;

  if (carefully_read(fd, 256*SECTORSZ, b, SECTORSZ, file) ||
      check_anchor_header(b, 256, CAHF_GRIPE | CAHF_FULL, file))
    goto end;

  for (i = 1; i < 32768; i++) {
    if (carefully_read(fd, (off_t)(end - i)*SECTORSZ, bb, SECTORSZ, file))
      goto end;
    if (bb[0] || !all_zero_p(bb, SECTORSZ)) goto nonzero;
  }
  gripe(1, "too many trailing zero sectors: "
	"couldn't find backup anchor descriptor in `%s'", file);
  goto end;
nonzero:
  j = i;
  for (;;) {
    if (bb[0] == 2 && !check_anchor_header(bb, end - j, 0, file))
      break;
    j++;
    if (j > i + 256) {
      gripe(1, "failed to find backup anchor descriptor in `%s'", file);
      goto end;
    }
    if (carefully_read(fd, (off_t)(end - j)*SECTORSZ, bb, SECTORSZ, file))
      goto end;
  }
  if (j > i) {
    gripe(1, "found backup anchor descriptor at sector %"PRIuSEC" "
	  " = %"PRIuSEC" from end, = %"PRIuSEC" from trailing zeros",
	  end - j, j, j - i + 1);
    i = j;
  }

  if (check_anchor_header(bb, end - i, CAHF_GRIPE | CAHF_FULL, file))
    goto end;

  if (MEMCMP(b + 16, != , bb + 16, SECTORSZ - 16)) {
    gripe(1, "backup anchor descriptor in sector %"PRIuSEC" "
	  "doesn't match primary in sector 256 of `%s'",
	  end - i, file);
    goto end;
  }

  if (i > 1) {
    if (!(flags&F_FIX))
      gripe(1, "%u trailing zero sectors in `%s'", i - 1, file);
    else {
      if (ftruncate(fd, (off_t)(end - i + 1)*SECTORSZ))
	gripe_syserr(2, errno,
		     "failed to truncate `%s' to %"PRIuSEC" sectors",
		     file, end - i + 1);
      else
	moan("removed %u trailing zero sectors from `%s'", i - 1, file);
    }
  }

end:
  if (fd != -1) close(fd);
}

static void usage(FILE *fp)
  { fprintf(fp, "usage: %s [-x] IMG ...\n", prog); }

int main(int argc, char *argv[])
{
  int i, opt;
  unsigned f = 0;
#define f_bogus 1u

  set_prog(argv[0]);
  for (;;) {
    opt = getopt(argc, argv, "hx"); if (opt < 0) break;
    switch (opt) {
      case 'h': usage(stdout); exit(0);
      case 'x': flags |= F_FIX; break;
      default: f |= f_bogus; break;
    }
  }
  if (optind >= argc) f |= f_bogus;
  if (f&f_bogus) { usage(stderr); exit(2); }

  for (i = optind; i < argc; i++) check_img(argv[i]);
  return (status);
}