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src/Source/LibJPEG/rdjpgcom.c  view on Meta::CPAN

  length -= 2;

  while (length > 0) {
    ch = read_1_byte();
    if (raw) {
      putc(ch, stdout);
    /* Emit the character in a readable form.
     * Nonprintables are converted to \nnn form,
     * while \ is converted to \\.
     * Newlines in CR, CR/LF, or LF form will be printed as one newline.
     */
    } else if (ch == '\r') {
      printf("\n");
    } else if (ch == '\n') {
      if (lastch != '\r')
	printf("\n");
    } else if (ch == '\\') {
      printf("\\\\");
    } else if (isprint(ch)) {
      putc(ch, stdout);
    } else {
      printf("\\%03o", ch);
    }
    lastch = ch;
    length--;
  }
  printf("\n");

  /* Bill Allombert: revert to C locale */
#ifdef HAVE_LOCALE_H
  setlocale(LC_CTYPE, "C");
#endif
}


/*
 * Process a SOFn marker.
 * This code is only needed if you want to know the image dimensions...
 */

static void
process_SOFn (int marker)
{
  unsigned int length;
  unsigned int image_height, image_width;
  int data_precision, num_components;
  const char * process;
  int ci;

  length = read_2_bytes();	/* usual parameter length count */

  data_precision = read_1_byte();
  image_height = read_2_bytes();
  image_width = read_2_bytes();
  num_components = read_1_byte();

  switch (marker) {
  case M_SOF0:	process = "Baseline";  break;
  case M_SOF1:	process = "Extended sequential";  break;
  case M_SOF2:	process = "Progressive";  break;
  case M_SOF3:	process = "Lossless";  break;
  case M_SOF5:	process = "Differential sequential";  break;
  case M_SOF6:	process = "Differential progressive";  break;
  case M_SOF7:	process = "Differential lossless";  break;
  case M_SOF9:	process = "Extended sequential, arithmetic coding";  break;
  case M_SOF10:	process = "Progressive, arithmetic coding";  break;
  case M_SOF11:	process = "Lossless, arithmetic coding";  break;
  case M_SOF13:	process = "Differential sequential, arithmetic coding";  break;
  case M_SOF14:	process = "Differential progressive, arithmetic coding"; break;
  case M_SOF15:	process = "Differential lossless, arithmetic coding";  break;
  default:	process = "Unknown";  break;
  }

  printf("JPEG image is %uw * %uh, %d color components, %d bits per sample\n",
	 image_width, image_height, num_components, data_precision);
  printf("JPEG process: %s\n", process);

  if (length != (unsigned int) (8 + num_components * 3))
    ERREXIT("Bogus SOF marker length");

  for (ci = 0; ci < num_components; ci++) {
    (void) read_1_byte();	/* Component ID code */
    (void) read_1_byte();	/* H, V sampling factors */
    (void) read_1_byte();	/* Quantization table number */
  }
}


/*
 * Parse the marker stream until SOS or EOI is seen;
 * display any COM markers.
 * While the companion program wrjpgcom will always insert COM markers before
 * SOFn, other implementations might not, so we scan to SOS before stopping.
 * If we were only interested in the image dimensions, we would stop at SOFn.
 * (Conversely, if we only cared about COM markers, there would be no need
 * for special code to handle SOFn; we could treat it like other markers.)
 */

static int
scan_JPEG_header (int verbose, int raw)
{
  int marker;

  /* Expect SOI at start of file */
  if (first_marker() != M_SOI)
    ERREXIT("Expected SOI marker first");

  /* Scan miscellaneous markers until we reach SOS. */
  for (;;) {
    marker = next_marker();
    switch (marker) {
      /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
       * treated as SOFn.  C4 in particular is actually DHT.
       */
    case M_SOF0:		/* Baseline */
    case M_SOF1:		/* Extended sequential, Huffman */
    case M_SOF2:		/* Progressive, Huffman */
    case M_SOF3:		/* Lossless, Huffman */
    case M_SOF5:		/* Differential sequential, Huffman */
    case M_SOF6:		/* Differential progressive, Huffman */
    case M_SOF7:		/* Differential lossless, Huffman */
    case M_SOF9:		/* Extended sequential, arithmetic */
    case M_SOF10:		/* Progressive, arithmetic */
    case M_SOF11:		/* Lossless, arithmetic */
    case M_SOF13:		/* Differential sequential, arithmetic */
    case M_SOF14:		/* Differential progressive, arithmetic */
    case M_SOF15:		/* Differential lossless, arithmetic */
      if (verbose)
	process_SOFn(marker);
      else
	skip_variable();
      break;

    case M_SOS:			/* stop before hitting compressed data */
      return marker;

    case M_EOI:			/* in case it's a tables-only JPEG stream */
      return marker;

    case M_COM:
      process_COM(raw);
      break;

    case M_APP12:
      /* Some digital camera makers put useful textual information into
       * APP12 markers, so we print those out too when in -verbose mode.
       */
      if (verbose) {
	printf("APP12 contains:\n");
	process_COM(raw);
      } else
	skip_variable();
      break;

    default:			/* Anything else just gets skipped */
      skip_variable();		/* we assume it has a parameter count... */
      break;
    }
  } /* end loop */
}


/* Command line parsing code */

static const char * progname;	/* program name for error messages */


static void
usage (void)
/* complain about bad command line */
{
  fprintf(stderr, "rdjpgcom displays any textual comments in a JPEG file.\n");

  fprintf(stderr, "Usage: %s [switches] [inputfile]\n", progname);

  fprintf(stderr, "Switches (names may be abbreviated):\n");
  fprintf(stderr, "  -raw        Display non-printable characters in comments (unsafe)\n");
  fprintf(stderr, "  -verbose    Also display dimensions of JPEG image\n");

  exit(EXIT_FAILURE);
}


static int
keymatch (char * arg, const char * keyword, int minchars)
/* Case-insensitive matching of (possibly abbreviated) keyword switches. */
/* keyword is the constant keyword (must be lower case already), */