source: trunk/libjpeg/rdjpgcom.c @ 426

Last change on this file since 426 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

File size: 14.6 KB
Line 
1/*
2 * rdjpgcom.c
3 *
4 * Copyright (C) 1994-1997, Thomas G. Lane.
5 * Modified 2009 by Bill Allombert, Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains a very simple stand-alone application that displays
10 * the text in COM (comment) markers in a JFIF file.
11 * This may be useful as an example of the minimum logic needed to parse
12 * JPEG markers.
13 */
14
15#define JPEG_CJPEG_DJPEG        /* to get the command-line config symbols */
16#include "jinclude.h"           /* get auto-config symbols, <stdio.h> */
17
18#ifdef HAVE_LOCALE_H
19#include <locale.h>             /* Bill Allombert: use locale for isprint */
20#endif
21#include <ctype.h>              /* to declare isupper(), tolower() */
22#ifdef USE_SETMODE
23#include <fcntl.h>              /* to declare setmode()'s parameter macros */
24/* If you have setmode() but not <io.h>, just delete this line: */
25#include <io.h>                 /* to declare setmode() */
26#endif
27
28#ifdef USE_CCOMMAND             /* command-line reader for Macintosh */
29#ifdef __MWERKS__
30#include <SIOUX.h>              /* Metrowerks needs this */
31#include <console.h>            /* ... and this */
32#endif
33#ifdef THINK_C
34#include <console.h>            /* Think declares it here */
35#endif
36#endif
37
38#ifdef DONT_USE_B_MODE          /* define mode parameters for fopen() */
39#define READ_BINARY     "r"
40#else
41#ifdef VMS                      /* VMS is very nonstandard */
42#define READ_BINARY     "rb", "ctx=stm"
43#else                           /* standard ANSI-compliant case */
44#define READ_BINARY     "rb"
45#endif
46#endif
47
48#ifndef EXIT_FAILURE            /* define exit() codes if not provided */
49#define EXIT_FAILURE  1
50#endif
51#ifndef EXIT_SUCCESS
52#ifdef VMS
53#define EXIT_SUCCESS  1         /* VMS is very nonstandard */
54#else
55#define EXIT_SUCCESS  0
56#endif
57#endif
58
59
60/*
61 * These macros are used to read the input file.
62 * To reuse this code in another application, you might need to change these.
63 */
64
65static FILE * infile;           /* input JPEG file */
66
67/* Return next input byte, or EOF if no more */
68#define NEXTBYTE()  getc(infile)
69
70
71/* Error exit handler */
72#define ERREXIT(msg)  (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))
73
74
75/* Read one byte, testing for EOF */
76static int
77read_1_byte (void)
78{
79  int c;
80
81  c = NEXTBYTE();
82  if (c == EOF)
83    ERREXIT("Premature EOF in JPEG file");
84  return c;
85}
86
87/* Read 2 bytes, convert to unsigned int */
88/* All 2-byte quantities in JPEG markers are MSB first */
89static unsigned int
90read_2_bytes (void)
91{
92  int c1, c2;
93
94  c1 = NEXTBYTE();
95  if (c1 == EOF)
96    ERREXIT("Premature EOF in JPEG file");
97  c2 = NEXTBYTE();
98  if (c2 == EOF)
99    ERREXIT("Premature EOF in JPEG file");
100  return (((unsigned int) c1) << 8) + ((unsigned int) c2);
101}
102
103
104/*
105 * JPEG markers consist of one or more 0xFF bytes, followed by a marker
106 * code byte (which is not an FF).  Here are the marker codes of interest
107 * in this program.  (See jdmarker.c for a more complete list.)
108 */
109
110#define M_SOF0  0xC0            /* Start Of Frame N */
111#define M_SOF1  0xC1            /* N indicates which compression process */
112#define M_SOF2  0xC2            /* Only SOF0-SOF2 are now in common use */
113#define M_SOF3  0xC3
114#define M_SOF5  0xC5            /* NB: codes C4 and CC are NOT SOF markers */
115#define M_SOF6  0xC6
116#define M_SOF7  0xC7
117#define M_SOF9  0xC9
118#define M_SOF10 0xCA
119#define M_SOF11 0xCB
120#define M_SOF13 0xCD
121#define M_SOF14 0xCE
122#define M_SOF15 0xCF
123#define M_SOI   0xD8            /* Start Of Image (beginning of datastream) */
124#define M_EOI   0xD9            /* End Of Image (end of datastream) */
125#define M_SOS   0xDA            /* Start Of Scan (begins compressed data) */
126#define M_APP0  0xE0            /* Application-specific marker, type N */
127#define M_APP12 0xEC            /* (we don't bother to list all 16 APPn's) */
128#define M_COM   0xFE            /* COMment */
129
130
131/*
132 * Find the next JPEG marker and return its marker code.
133 * We expect at least one FF byte, possibly more if the compressor used FFs
134 * to pad the file.
135 * There could also be non-FF garbage between markers.  The treatment of such
136 * garbage is unspecified; we choose to skip over it but emit a warning msg.
137 * NB: this routine must not be used after seeing SOS marker, since it will
138 * not deal correctly with FF/00 sequences in the compressed image data...
139 */
140
141static int
142next_marker (void)
143{
144  int c;
145  int discarded_bytes = 0;
146
147  /* Find 0xFF byte; count and skip any non-FFs. */
148  c = read_1_byte();
149  while (c != 0xFF) {
150    discarded_bytes++;
151    c = read_1_byte();
152  }
153  /* Get marker code byte, swallowing any duplicate FF bytes.  Extra FFs
154   * are legal as pad bytes, so don't count them in discarded_bytes.
155   */
156  do {
157    c = read_1_byte();
158  } while (c == 0xFF);
159
160  if (discarded_bytes != 0) {
161    fprintf(stderr, "Warning: garbage data found in JPEG file\n");
162  }
163
164  return c;
165}
166
167
168/*
169 * Read the initial marker, which should be SOI.
170 * For a JFIF file, the first two bytes of the file should be literally
171 * 0xFF M_SOI.  To be more general, we could use next_marker, but if the
172 * input file weren't actually JPEG at all, next_marker might read the whole
173 * file and then return a misleading error message...
174 */
175
176static int
177first_marker (void)
178{
179  int c1, c2;
180
181  c1 = NEXTBYTE();
182  c2 = NEXTBYTE();
183  if (c1 != 0xFF || c2 != M_SOI)
184    ERREXIT("Not a JPEG file");
185  return c2;
186}
187
188
189/*
190 * Most types of marker are followed by a variable-length parameter segment.
191 * This routine skips over the parameters for any marker we don't otherwise
192 * want to process.
193 * Note that we MUST skip the parameter segment explicitly in order not to
194 * be fooled by 0xFF bytes that might appear within the parameter segment;
195 * such bytes do NOT introduce new markers.
196 */
197
198static void
199skip_variable (void)
200/* Skip over an unknown or uninteresting variable-length marker */
201{
202  unsigned int length;
203
204  /* Get the marker parameter length count */
205  length = read_2_bytes();
206  /* Length includes itself, so must be at least 2 */
207  if (length < 2)
208    ERREXIT("Erroneous JPEG marker length");
209  length -= 2;
210  /* Skip over the remaining bytes */
211  while (length > 0) {
212    (void) read_1_byte();
213    length--;
214  }
215}
216
217
218/*
219 * Process a COM marker.
220 * We want to print out the marker contents as legible text;
221 * we must guard against non-text junk and varying newline representations.
222 */
223
224static void
225process_COM (int raw)
226{
227  unsigned int length;
228  int ch;
229  int lastch = 0;
230
231  /* Bill Allombert: set locale properly for isprint */
232#ifdef HAVE_LOCALE_H
233  setlocale(LC_CTYPE, "");
234#endif
235
236  /* Get the marker parameter length count */
237  length = read_2_bytes();
238  /* Length includes itself, so must be at least 2 */
239  if (length < 2)
240    ERREXIT("Erroneous JPEG marker length");
241  length -= 2;
242
243  while (length > 0) {
244    ch = read_1_byte();
245    if (raw) {
246      putc(ch, stdout);
247    /* Emit the character in a readable form.
248     * Nonprintables are converted to \nnn form,
249     * while \ is converted to \\.
250     * Newlines in CR, CR/LF, or LF form will be printed as one newline.
251     */
252    } else if (ch == '\r') {
253      printf("\n");
254    } else if (ch == '\n') {
255      if (lastch != '\r')
256        printf("\n");
257    } else if (ch == '\\') {
258      printf("\\\\");
259    } else if (isprint(ch)) {
260      putc(ch, stdout);
261    } else {
262      printf("\\%03o", ch);
263    }
264    lastch = ch;
265    length--;
266  }
267  printf("\n");
268
269  /* Bill Allombert: revert to C locale */
270#ifdef HAVE_LOCALE_H
271  setlocale(LC_CTYPE, "C");
272#endif
273}
274
275
276/*
277 * Process a SOFn marker.
278 * This code is only needed if you want to know the image dimensions...
279 */
280
281static void
282process_SOFn (int marker)
283{
284  unsigned int length;
285  unsigned int image_height, image_width;
286  int data_precision, num_components;
287  const char * process;
288  int ci;
289
290  length = read_2_bytes();      /* usual parameter length count */
291
292  data_precision = read_1_byte();
293  image_height = read_2_bytes();
294  image_width = read_2_bytes();
295  num_components = read_1_byte();
296
297  switch (marker) {
298  case M_SOF0:  process = "Baseline";  break;
299  case M_SOF1:  process = "Extended sequential";  break;
300  case M_SOF2:  process = "Progressive";  break;
301  case M_SOF3:  process = "Lossless";  break;
302  case M_SOF5:  process = "Differential sequential";  break;
303  case M_SOF6:  process = "Differential progressive";  break;
304  case M_SOF7:  process = "Differential lossless";  break;
305  case M_SOF9:  process = "Extended sequential, arithmetic coding";  break;
306  case M_SOF10: process = "Progressive, arithmetic coding";  break;
307  case M_SOF11: process = "Lossless, arithmetic coding";  break;
308  case M_SOF13: process = "Differential sequential, arithmetic coding";  break;
309  case M_SOF14: process = "Differential progressive, arithmetic coding"; break;
310  case M_SOF15: process = "Differential lossless, arithmetic coding";  break;
311  default:      process = "Unknown";  break;
312  }
313
314  printf("JPEG image is %uw * %uh, %d color components, %d bits per sample\n",
315         image_width, image_height, num_components, data_precision);
316  printf("JPEG process: %s\n", process);
317
318  if (length != (unsigned int) (8 + num_components * 3))
319    ERREXIT("Bogus SOF marker length");
320
321  for (ci = 0; ci < num_components; ci++) {
322    (void) read_1_byte();       /* Component ID code */
323    (void) read_1_byte();       /* H, V sampling factors */
324    (void) read_1_byte();       /* Quantization table number */
325  }
326}
327
328
329/*
330 * Parse the marker stream until SOS or EOI is seen;
331 * display any COM markers.
332 * While the companion program wrjpgcom will always insert COM markers before
333 * SOFn, other implementations might not, so we scan to SOS before stopping.
334 * If we were only interested in the image dimensions, we would stop at SOFn.
335 * (Conversely, if we only cared about COM markers, there would be no need
336 * for special code to handle SOFn; we could treat it like other markers.)
337 */
338
339static int
340scan_JPEG_header (int verbose, int raw)
341{
342  int marker;
343
344  /* Expect SOI at start of file */
345  if (first_marker() != M_SOI)
346    ERREXIT("Expected SOI marker first");
347
348  /* Scan miscellaneous markers until we reach SOS. */
349  for (;;) {
350    marker = next_marker();
351    switch (marker) {
352      /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
353       * treated as SOFn.  C4 in particular is actually DHT.
354       */
355    case M_SOF0:                /* Baseline */
356    case M_SOF1:                /* Extended sequential, Huffman */
357    case M_SOF2:                /* Progressive, Huffman */
358    case M_SOF3:                /* Lossless, Huffman */
359    case M_SOF5:                /* Differential sequential, Huffman */
360    case M_SOF6:                /* Differential progressive, Huffman */
361    case M_SOF7:                /* Differential lossless, Huffman */
362    case M_SOF9:                /* Extended sequential, arithmetic */
363    case M_SOF10:               /* Progressive, arithmetic */
364    case M_SOF11:               /* Lossless, arithmetic */
365    case M_SOF13:               /* Differential sequential, arithmetic */
366    case M_SOF14:               /* Differential progressive, arithmetic */
367    case M_SOF15:               /* Differential lossless, arithmetic */
368      if (verbose)
369        process_SOFn(marker);
370      else
371        skip_variable();
372      break;
373
374    case M_SOS:                 /* stop before hitting compressed data */
375      return marker;
376
377    case M_EOI:                 /* in case it's a tables-only JPEG stream */
378      return marker;
379
380    case M_COM:
381      process_COM(raw);
382      break;
383
384    case M_APP12:
385      /* Some digital camera makers put useful textual information into
386       * APP12 markers, so we print those out too when in -verbose mode.
387       */
388      if (verbose) {
389        printf("APP12 contains:\n");
390        process_COM(raw);
391      } else
392        skip_variable();
393      break;
394
395    default:                    /* Anything else just gets skipped */
396      skip_variable();          /* we assume it has a parameter count... */
397      break;
398    }
399  } /* end loop */
400}
401
402
403/* Command line parsing code */
404
405static const char * progname;   /* program name for error messages */
406
407
408static void
409usage (void)
410/* complain about bad command line */
411{
412  fprintf(stderr, "rdjpgcom displays any textual comments in a JPEG file.\n");
413
414  fprintf(stderr, "Usage: %s [switches] [inputfile]\n", progname);
415
416  fprintf(stderr, "Switches (names may be abbreviated):\n");
417  fprintf(stderr, "  -raw        Display non-printable characters in comments (unsafe)\n");
418  fprintf(stderr, "  -verbose    Also display dimensions of JPEG image\n");
419
420  exit(EXIT_FAILURE);
421}
422
423
424static int
425keymatch (char * arg, const char * keyword, int minchars)
426/* Case-insensitive matching of (possibly abbreviated) keyword switches. */
427/* keyword is the constant keyword (must be lower case already), */
428/* minchars is length of minimum legal abbreviation. */
429{
430  register int ca, ck;
431  register int nmatched = 0;
432
433  while ((ca = *arg++) != '\0') {
434    if ((ck = *keyword++) == '\0')
435      return 0;                 /* arg longer than keyword, no good */
436    if (isupper(ca))            /* force arg to lcase (assume ck is already) */
437      ca = tolower(ca);
438    if (ca != ck)
439      return 0;                 /* no good */
440    nmatched++;                 /* count matched characters */
441  }
442  /* reached end of argument; fail if it's too short for unique abbrev */
443  if (nmatched < minchars)
444    return 0;
445  return 1;                     /* A-OK */
446}
447
448
449/*
450 * The main program.
451 */
452
453int
454main (int argc, char **argv)
455{
456  int argn;
457  char * arg;
458  int verbose = 0, raw = 0;
459
460  /* On Mac, fetch a command line. */
461#ifdef USE_CCOMMAND
462  argc = ccommand(&argv);
463#endif
464
465  progname = argv[0];
466  if (progname == NULL || progname[0] == 0)
467    progname = "rdjpgcom";      /* in case C library doesn't provide it */
468
469  /* Parse switches, if any */
470  for (argn = 1; argn < argc; argn++) {
471    arg = argv[argn];
472    if (arg[0] != '-')
473      break;                    /* not switch, must be file name */
474    arg++;                      /* advance over '-' */
475    if (keymatch(arg, "verbose", 1)) {
476      verbose++;
477    } else if (keymatch(arg, "raw", 1)) {
478      raw = 1;
479    } else
480      usage();
481  }
482
483  /* Open the input file. */
484  /* Unix style: expect zero or one file name */
485  if (argn < argc-1) {
486    fprintf(stderr, "%s: only one input file\n", progname);
487    usage();
488  }
489  if (argn < argc) {
490    if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {
491      fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
492      exit(EXIT_FAILURE);
493    }
494  } else {
495    /* default input file is stdin */
496#ifdef USE_SETMODE              /* need to hack file mode? */
497    setmode(fileno(stdin), O_BINARY);
498#endif
499#ifdef USE_FDOPEN               /* need to re-open in binary mode? */
500    if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {
501      fprintf(stderr, "%s: can't open stdin\n", progname);
502      exit(EXIT_FAILURE);
503    }
504#else
505    infile = stdin;
506#endif
507  }
508
509  /* Scan the JPEG headers. */
510  (void) scan_JPEG_header(verbose, raw);
511
512  /* All done. */
513  exit(EXIT_SUCCESS);
514  return 0;                     /* suppress no-return-value warnings */
515}
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