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Thomas G. Lane36a4ccc1994-09-24 00:00:00 +00001/*
2 * rdjpgcom.c
3 *
DRCa8fb48b2014-05-29 19:31:45 +00004 * This file was part of the Independent JPEG Group's software:
Thomas G. Lane5ead57a1998-03-27 00:00:00 +00005 * Copyright (C) 1994-1997, Thomas G. Lane.
Guido Vollbeding5996a252009-06-27 00:00:00 +00006 * Modified 2009 by Bill Allombert, Guido Vollbeding.
DRCa8fb48b2014-05-29 19:31:45 +00007 * It was modified by The libjpeg-turbo Project to include only code relevant
8 * to libjpeg-turbo.
DRC7e3acc02015-10-10 10:25:46 -05009 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000011 *
12 * This file contains a very simple stand-alone application that displays
13 * the text in COM (comment) markers in a JFIF file.
14 * This may be useful as an example of the minimum logic needed to parse
15 * JPEG markers.
16 */
17
DRCe5eaf372014-05-09 18:00:32 +000018#define JPEG_CJPEG_DJPEG /* to get the command-line config symbols */
19#include "jinclude.h" /* get auto-config symbols, <stdio.h> */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000020
Guido Vollbeding5996a252009-06-27 00:00:00 +000021#ifdef HAVE_LOCALE_H
DRCe5eaf372014-05-09 18:00:32 +000022#include <locale.h> /* Bill Allombert: use locale for isprint */
Guido Vollbeding5996a252009-06-27 00:00:00 +000023#endif
DRCe5eaf372014-05-09 18:00:32 +000024#include <ctype.h> /* to declare isupper(), tolower() */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000025#ifdef USE_SETMODE
DRCe5eaf372014-05-09 18:00:32 +000026#include <fcntl.h> /* to declare setmode()'s parameter macros */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000027/* If you have setmode() but not <io.h>, just delete this line: */
DRCe5eaf372014-05-09 18:00:32 +000028#include <io.h> /* to declare setmode() */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000029#endif
30
DRCe5eaf372014-05-09 18:00:32 +000031#ifdef USE_CCOMMAND /* command-line reader for Macintosh */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000032#ifdef __MWERKS__
Thomas G. Lane489583f1996-02-07 00:00:00 +000033#include <SIOUX.h> /* Metrowerks needs this */
DRCe5eaf372014-05-09 18:00:32 +000034#include <console.h> /* ... and this */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000035#endif
36#ifdef THINK_C
DRCe5eaf372014-05-09 18:00:32 +000037#include <console.h> /* Think declares it here */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000038#endif
39#endif
40
DRCe5eaf372014-05-09 18:00:32 +000041#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
42#define READ_BINARY "r"
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000043#else
DRCe5eaf372014-05-09 18:00:32 +000044#define READ_BINARY "rb"
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000045#endif
46
DRCe5eaf372014-05-09 18:00:32 +000047#ifndef EXIT_FAILURE /* define exit() codes if not provided */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000048#define EXIT_FAILURE 1
49#endif
50#ifndef EXIT_SUCCESS
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000051#define EXIT_SUCCESS 0
52#endif
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000053
54
55/*
56 * These macros are used to read the input file.
57 * To reuse this code in another application, you might need to change these.
58 */
59
DRCbd498032016-02-19 08:53:33 -060060static FILE *infile; /* input JPEG file */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +000061
62/* Return next input byte, or EOF if no more */
63#define NEXTBYTE() getc(infile)
64
65
66/* Error exit handler */
67#define ERREXIT(msg) (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))
68
69
70/* Read one byte, testing for EOF */
71static int
72read_1_byte (void)
73{
74 int c;
75
76 c = NEXTBYTE();
77 if (c == EOF)
78 ERREXIT("Premature EOF in JPEG file");
79 return c;
80}
81
82/* Read 2 bytes, convert to unsigned int */
83/* All 2-byte quantities in JPEG markers are MSB first */
84static unsigned int
85read_2_bytes (void)
86{
87 int c1, c2;
88
89 c1 = NEXTBYTE();
90 if (c1 == EOF)
91 ERREXIT("Premature EOF in JPEG file");
92 c2 = NEXTBYTE();
93 if (c2 == EOF)
94 ERREXIT("Premature EOF in JPEG file");
95 return (((unsigned int) c1) << 8) + ((unsigned int) c2);
96}
97
98
99/*
100 * JPEG markers consist of one or more 0xFF bytes, followed by a marker
101 * code byte (which is not an FF). Here are the marker codes of interest
102 * in this program. (See jdmarker.c for a more complete list.)
103 */
104
DRCe5eaf372014-05-09 18:00:32 +0000105#define M_SOF0 0xC0 /* Start Of Frame N */
106#define M_SOF1 0xC1 /* N indicates which compression process */
107#define M_SOF2 0xC2 /* Only SOF0-SOF2 are now in common use */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000108#define M_SOF3 0xC3
DRCe5eaf372014-05-09 18:00:32 +0000109#define M_SOF5 0xC5 /* NB: codes C4 and CC are NOT SOF markers */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000110#define M_SOF6 0xC6
111#define M_SOF7 0xC7
112#define M_SOF9 0xC9
113#define M_SOF10 0xCA
114#define M_SOF11 0xCB
115#define M_SOF13 0xCD
116#define M_SOF14 0xCE
117#define M_SOF15 0xCF
DRCe5eaf372014-05-09 18:00:32 +0000118#define M_SOI 0xD8 /* Start Of Image (beginning of datastream) */
119#define M_EOI 0xD9 /* End Of Image (end of datastream) */
120#define M_SOS 0xDA /* Start Of Scan (begins compressed data) */
121#define M_APP0 0xE0 /* Application-specific marker, type N */
122#define M_APP12 0xEC /* (we don't bother to list all 16 APPn's) */
123#define M_COM 0xFE /* COMment */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000124
125
126/*
127 * Find the next JPEG marker and return its marker code.
128 * We expect at least one FF byte, possibly more if the compressor used FFs
129 * to pad the file.
130 * There could also be non-FF garbage between markers. The treatment of such
131 * garbage is unspecified; we choose to skip over it but emit a warning msg.
132 * NB: this routine must not be used after seeing SOS marker, since it will
133 * not deal correctly with FF/00 sequences in the compressed image data...
134 */
135
136static int
137next_marker (void)
138{
139 int c;
140 int discarded_bytes = 0;
141
142 /* Find 0xFF byte; count and skip any non-FFs. */
143 c = read_1_byte();
144 while (c != 0xFF) {
145 discarded_bytes++;
146 c = read_1_byte();
147 }
148 /* Get marker code byte, swallowing any duplicate FF bytes. Extra FFs
149 * are legal as pad bytes, so don't count them in discarded_bytes.
150 */
151 do {
152 c = read_1_byte();
153 } while (c == 0xFF);
154
155 if (discarded_bytes != 0) {
156 fprintf(stderr, "Warning: garbage data found in JPEG file\n");
157 }
158
159 return c;
160}
161
162
163/*
164 * Read the initial marker, which should be SOI.
165 * For a JFIF file, the first two bytes of the file should be literally
166 * 0xFF M_SOI. To be more general, we could use next_marker, but if the
167 * input file weren't actually JPEG at all, next_marker might read the whole
168 * file and then return a misleading error message...
169 */
170
171static int
172first_marker (void)
173{
174 int c1, c2;
175
176 c1 = NEXTBYTE();
177 c2 = NEXTBYTE();
178 if (c1 != 0xFF || c2 != M_SOI)
179 ERREXIT("Not a JPEG file");
180 return c2;
181}
182
183
184/*
185 * Most types of marker are followed by a variable-length parameter segment.
186 * This routine skips over the parameters for any marker we don't otherwise
187 * want to process.
188 * Note that we MUST skip the parameter segment explicitly in order not to
189 * be fooled by 0xFF bytes that might appear within the parameter segment;
190 * such bytes do NOT introduce new markers.
191 */
192
193static void
194skip_variable (void)
195/* Skip over an unknown or uninteresting variable-length marker */
196{
197 unsigned int length;
198
199 /* Get the marker parameter length count */
200 length = read_2_bytes();
201 /* Length includes itself, so must be at least 2 */
202 if (length < 2)
203 ERREXIT("Erroneous JPEG marker length");
204 length -= 2;
205 /* Skip over the remaining bytes */
206 while (length > 0) {
207 (void) read_1_byte();
208 length--;
209 }
210}
211
212
213/*
214 * Process a COM marker.
215 * We want to print out the marker contents as legible text;
Thomas G. Lane5ead57a1998-03-27 00:00:00 +0000216 * we must guard against non-text junk and varying newline representations.
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000217 */
218
219static void
Guido Vollbeding5996a252009-06-27 00:00:00 +0000220process_COM (int raw)
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000221{
222 unsigned int length;
223 int ch;
224 int lastch = 0;
225
Guido Vollbeding5996a252009-06-27 00:00:00 +0000226 /* Bill Allombert: set locale properly for isprint */
227#ifdef HAVE_LOCALE_H
228 setlocale(LC_CTYPE, "");
229#endif
230
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000231 /* Get the marker parameter length count */
232 length = read_2_bytes();
233 /* Length includes itself, so must be at least 2 */
234 if (length < 2)
235 ERREXIT("Erroneous JPEG marker length");
236 length -= 2;
237
238 while (length > 0) {
239 ch = read_1_byte();
Guido Vollbeding5996a252009-06-27 00:00:00 +0000240 if (raw) {
241 putc(ch, stdout);
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000242 /* Emit the character in a readable form.
243 * Nonprintables are converted to \nnn form,
244 * while \ is converted to \\.
245 * Newlines in CR, CR/LF, or LF form will be printed as one newline.
246 */
Guido Vollbeding5996a252009-06-27 00:00:00 +0000247 } else if (ch == '\r') {
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000248 printf("\n");
249 } else if (ch == '\n') {
250 if (lastch != '\r')
DRCe5eaf372014-05-09 18:00:32 +0000251 printf("\n");
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000252 } else if (ch == '\\') {
253 printf("\\\\");
254 } else if (isprint(ch)) {
255 putc(ch, stdout);
256 } else {
257 printf("\\%03o", ch);
258 }
259 lastch = ch;
260 length--;
261 }
262 printf("\n");
Guido Vollbeding5996a252009-06-27 00:00:00 +0000263
264 /* Bill Allombert: revert to C locale */
265#ifdef HAVE_LOCALE_H
266 setlocale(LC_CTYPE, "C");
267#endif
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000268}
269
270
271/*
272 * Process a SOFn marker.
273 * This code is only needed if you want to know the image dimensions...
274 */
275
276static void
277process_SOFn (int marker)
278{
279 unsigned int length;
280 unsigned int image_height, image_width;
281 int data_precision, num_components;
DRCbd498032016-02-19 08:53:33 -0600282 const char *process;
Thomas G. Lanea8b67c41995-03-15 00:00:00 +0000283 int ci;
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000284
DRCe5eaf372014-05-09 18:00:32 +0000285 length = read_2_bytes(); /* usual parameter length count */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000286
287 data_precision = read_1_byte();
288 image_height = read_2_bytes();
289 image_width = read_2_bytes();
290 num_components = read_1_byte();
291
292 switch (marker) {
DRCe5eaf372014-05-09 18:00:32 +0000293 case M_SOF0: process = "Baseline"; break;
294 case M_SOF1: process = "Extended sequential"; break;
295 case M_SOF2: process = "Progressive"; break;
296 case M_SOF3: process = "Lossless"; break;
297 case M_SOF5: process = "Differential sequential"; break;
298 case M_SOF6: process = "Differential progressive"; break;
299 case M_SOF7: process = "Differential lossless"; break;
300 case M_SOF9: process = "Extended sequential, arithmetic coding"; break;
301 case M_SOF10: process = "Progressive, arithmetic coding"; break;
302 case M_SOF11: process = "Lossless, arithmetic coding"; break;
303 case M_SOF13: process = "Differential sequential, arithmetic coding"; break;
304 case M_SOF14: process = "Differential progressive, arithmetic coding"; break;
305 case M_SOF15: process = "Differential lossless, arithmetic coding"; break;
306 default: process = "Unknown"; break;
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000307 }
308
309 printf("JPEG image is %uw * %uh, %d color components, %d bits per sample\n",
DRCe5eaf372014-05-09 18:00:32 +0000310 image_width, image_height, num_components, data_precision);
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000311 printf("JPEG process: %s\n", process);
312
313 if (length != (unsigned int) (8 + num_components * 3))
314 ERREXIT("Bogus SOF marker length");
315
316 for (ci = 0; ci < num_components; ci++) {
DRCe5eaf372014-05-09 18:00:32 +0000317 (void) read_1_byte(); /* Component ID code */
318 (void) read_1_byte(); /* H, V sampling factors */
319 (void) read_1_byte(); /* Quantization table number */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000320 }
321}
322
323
324/*
325 * Parse the marker stream until SOS or EOI is seen;
326 * display any COM markers.
327 * While the companion program wrjpgcom will always insert COM markers before
328 * SOFn, other implementations might not, so we scan to SOS before stopping.
329 * If we were only interested in the image dimensions, we would stop at SOFn.
330 * (Conversely, if we only cared about COM markers, there would be no need
331 * for special code to handle SOFn; we could treat it like other markers.)
332 */
333
334static int
Guido Vollbeding5996a252009-06-27 00:00:00 +0000335scan_JPEG_header (int verbose, int raw)
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000336{
337 int marker;
338
339 /* Expect SOI at start of file */
340 if (first_marker() != M_SOI)
341 ERREXIT("Expected SOI marker first");
342
343 /* Scan miscellaneous markers until we reach SOS. */
344 for (;;) {
345 marker = next_marker();
346 switch (marker) {
Thomas G. Lane5ead57a1998-03-27 00:00:00 +0000347 /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
348 * treated as SOFn. C4 in particular is actually DHT.
349 */
DRCe5eaf372014-05-09 18:00:32 +0000350 case M_SOF0: /* Baseline */
351 case M_SOF1: /* Extended sequential, Huffman */
352 case M_SOF2: /* Progressive, Huffman */
353 case M_SOF3: /* Lossless, Huffman */
354 case M_SOF5: /* Differential sequential, Huffman */
355 case M_SOF6: /* Differential progressive, Huffman */
356 case M_SOF7: /* Differential lossless, Huffman */
357 case M_SOF9: /* Extended sequential, arithmetic */
358 case M_SOF10: /* Progressive, arithmetic */
359 case M_SOF11: /* Lossless, arithmetic */
360 case M_SOF13: /* Differential sequential, arithmetic */
361 case M_SOF14: /* Differential progressive, arithmetic */
362 case M_SOF15: /* Differential lossless, arithmetic */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000363 if (verbose)
DRCe5eaf372014-05-09 18:00:32 +0000364 process_SOFn(marker);
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000365 else
DRCe5eaf372014-05-09 18:00:32 +0000366 skip_variable();
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000367 break;
368
DRCe5eaf372014-05-09 18:00:32 +0000369 case M_SOS: /* stop before hitting compressed data */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000370 return marker;
371
DRCe5eaf372014-05-09 18:00:32 +0000372 case M_EOI: /* in case it's a tables-only JPEG stream */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000373 return marker;
374
375 case M_COM:
Guido Vollbeding5996a252009-06-27 00:00:00 +0000376 process_COM(raw);
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000377 break;
378
Thomas G. Lane5ead57a1998-03-27 00:00:00 +0000379 case M_APP12:
380 /* Some digital camera makers put useful textual information into
381 * APP12 markers, so we print those out too when in -verbose mode.
382 */
383 if (verbose) {
DRCe5eaf372014-05-09 18:00:32 +0000384 printf("APP12 contains:\n");
385 process_COM(raw);
Thomas G. Lane5ead57a1998-03-27 00:00:00 +0000386 } else
DRCe5eaf372014-05-09 18:00:32 +0000387 skip_variable();
Thomas G. Lane5ead57a1998-03-27 00:00:00 +0000388 break;
389
DRCe5eaf372014-05-09 18:00:32 +0000390 default: /* Anything else just gets skipped */
391 skip_variable(); /* we assume it has a parameter count... */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000392 break;
393 }
394 } /* end loop */
395}
396
397
398/* Command line parsing code */
399
DRCbd498032016-02-19 08:53:33 -0600400static const char *progname; /* program name for error messages */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000401
402
403static void
404usage (void)
405/* complain about bad command line */
406{
407 fprintf(stderr, "rdjpgcom displays any textual comments in a JPEG file.\n");
408
409 fprintf(stderr, "Usage: %s [switches] [inputfile]\n", progname);
410
411 fprintf(stderr, "Switches (names may be abbreviated):\n");
Guido Vollbeding5996a252009-06-27 00:00:00 +0000412 fprintf(stderr, " -raw Display non-printable characters in comments (unsafe)\n");
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000413 fprintf(stderr, " -verbose Also display dimensions of JPEG image\n");
414
415 exit(EXIT_FAILURE);
416}
417
418
419static int
DRCbd498032016-02-19 08:53:33 -0600420keymatch (char *arg, const char *keyword, int minchars)
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000421/* Case-insensitive matching of (possibly abbreviated) keyword switches. */
422/* keyword is the constant keyword (must be lower case already), */
423/* minchars is length of minimum legal abbreviation. */
424{
425 register int ca, ck;
426 register int nmatched = 0;
427
428 while ((ca = *arg++) != '\0') {
429 if ((ck = *keyword++) == '\0')
DRCe5eaf372014-05-09 18:00:32 +0000430 return 0; /* arg longer than keyword, no good */
431 if (isupper(ca)) /* force arg to lcase (assume ck is already) */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000432 ca = tolower(ca);
433 if (ca != ck)
DRCe5eaf372014-05-09 18:00:32 +0000434 return 0; /* no good */
435 nmatched++; /* count matched characters */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000436 }
437 /* reached end of argument; fail if it's too short for unique abbrev */
438 if (nmatched < minchars)
439 return 0;
DRCe5eaf372014-05-09 18:00:32 +0000440 return 1; /* A-OK */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000441}
442
443
444/*
445 * The main program.
446 */
447
448int
449main (int argc, char **argv)
450{
451 int argn;
DRCbd498032016-02-19 08:53:33 -0600452 char *arg;
Guido Vollbeding5996a252009-06-27 00:00:00 +0000453 int verbose = 0, raw = 0;
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000454
455 /* On Mac, fetch a command line. */
456#ifdef USE_CCOMMAND
457 argc = ccommand(&argv);
458#endif
459
460 progname = argv[0];
461 if (progname == NULL || progname[0] == 0)
DRCe5eaf372014-05-09 18:00:32 +0000462 progname = "rdjpgcom"; /* in case C library doesn't provide it */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000463
464 /* Parse switches, if any */
465 for (argn = 1; argn < argc; argn++) {
466 arg = argv[argn];
467 if (arg[0] != '-')
DRCe5eaf372014-05-09 18:00:32 +0000468 break; /* not switch, must be file name */
469 arg++; /* advance over '-' */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000470 if (keymatch(arg, "verbose", 1)) {
471 verbose++;
Guido Vollbeding5996a252009-06-27 00:00:00 +0000472 } else if (keymatch(arg, "raw", 1)) {
473 raw = 1;
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000474 } else
475 usage();
476 }
477
478 /* Open the input file. */
479 /* Unix style: expect zero or one file name */
480 if (argn < argc-1) {
481 fprintf(stderr, "%s: only one input file\n", progname);
482 usage();
483 }
484 if (argn < argc) {
485 if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {
486 fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
487 exit(EXIT_FAILURE);
488 }
489 } else {
490 /* default input file is stdin */
DRCe5eaf372014-05-09 18:00:32 +0000491#ifdef USE_SETMODE /* need to hack file mode? */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000492 setmode(fileno(stdin), O_BINARY);
493#endif
DRCe5eaf372014-05-09 18:00:32 +0000494#ifdef USE_FDOPEN /* need to re-open in binary mode? */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000495 if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {
496 fprintf(stderr, "%s: can't open stdin\n", progname);
497 exit(EXIT_FAILURE);
498 }
499#else
500 infile = stdin;
501#endif
502 }
503
504 /* Scan the JPEG headers. */
Guido Vollbeding5996a252009-06-27 00:00:00 +0000505 (void) scan_JPEG_header(verbose, raw);
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000506
507 /* All done. */
508 exit(EXIT_SUCCESS);
DRCe5eaf372014-05-09 18:00:32 +0000509 return 0; /* suppress no-return-value warnings */
Thomas G. Lane36a4ccc1994-09-24 00:00:00 +0000510}