1 /*
2 * wrjpgcom.c
3 *
4 * Copyright (C) 1994-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains a very simple stand-alone application that inserts
9 * user-supplied text as a COM (comment) marker in a JFIF file.
10 * This may be useful as an example of the minimum logic needed to parse
11 * JPEG markers.
12 */
13
14 #define JPEG_CJPEG_DJPEG /* to get the command-line config symbols */
15 #include "jinclude.h" /* get auto-config symbols, <stdio.h> */
16
17 #ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc() */
18 extern void * malloc ();
19 #endif
20 #include <ctype.h> /* to declare isupper(), tolower() */
21 #ifdef USE_SETMODE
22 #include <fcntl.h> /* to declare setmode()'s parameter macros */
23 /* If you have setmode() but not <io.h>, just delete this line: */
24 #include <io.h> /* to declare setmode() */
25 #endif
26
27 #ifdef USE_CCOMMAND /* command-line reader for Macintosh */
28 #ifdef __MWERKS__
29 #include <SIOUX.h> /* Metrowerks needs this */
30 #include <console.h> /* ... and this */
31 #endif
32 #ifdef THINK_C
33 #include <console.h> /* Think declares it here */
34 #endif
35 #endif
36
37 #ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
38 #define READ_BINARY "r"
39 #define WRITE_BINARY "w"
40 #else
41 #ifdef VMS /* VMS is very nonstandard */
42 #define READ_BINARY "rb", "ctx=stm"
43 #define WRITE_BINARY "wb", "ctx=stm"
44 #else /* standard ANSI-compliant case */
45 #define READ_BINARY "rb"
46 #define WRITE_BINARY "wb"
47 #endif
48 #endif
49
50 #ifndef EXIT_FAILURE /* define exit() codes if not provided */
51 #define EXIT_FAILURE 1
52 #endif
53 #ifndef EXIT_SUCCESS
54 #ifdef VMS
55 #define EXIT_SUCCESS 1 /* VMS is very nonstandard */
56 #else
57 #define EXIT_SUCCESS 0
58 #endif
59 #endif
60
61 /* Reduce this value if your malloc() can't allocate blocks up to 64K.
62 * On DOS, compiling in large model is usually a better solution.
63 */
64
65 #ifndef MAX_COM_LENGTH
66 #define MAX_COM_LENGTH 65000L /* must be <= 65533 in any case */
67 #endif
68
69
70 /*
71 * These macros are used to read the input file and write the output file.
72 * To reuse this code in another application, you might need to change these.
73 */
74
75 static FILE * infile; /* input JPEG file */
76
77 /* Return next input byte, or EOF if no more */
78 #define NEXTBYTE() getc(infile)
79
80 static FILE * outfile; /* output JPEG file */
81
82 /* Emit an output byte */
83 #define PUTBYTE(x) putc((x), outfile)
84
85
86 /* Error exit handler */
87 #define ERREXIT(msg) (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))
88
89
90 /* Read one byte, testing for EOF */
91 static int
read_1_byte(void)92 read_1_byte (void)
93 {
94 int c;
95
96 c = NEXTBYTE();
97 if (c == EOF)
98 ERREXIT("Premature EOF in JPEG file");
99 return c;
100 }
101
102 /* Read 2 bytes, convert to unsigned int */
103 /* All 2-byte quantities in JPEG markers are MSB first */
104 static unsigned int
read_2_bytes(void)105 read_2_bytes (void)
106 {
107 int c1, c2;
108
109 c1 = NEXTBYTE();
110 if (c1 == EOF)
111 ERREXIT("Premature EOF in JPEG file");
112 c2 = NEXTBYTE();
113 if (c2 == EOF)
114 ERREXIT("Premature EOF in JPEG file");
115 return (((unsigned int) c1) << 8) + ((unsigned int) c2);
116 }
117
118
119 /* Routines to write data to output file */
120
121 static void
write_1_byte(int c)122 write_1_byte (int c)
123 {
124 PUTBYTE(c);
125 }
126
127 static void
write_2_bytes(unsigned int val)128 write_2_bytes (unsigned int val)
129 {
130 PUTBYTE((val >> 8) & 0xFF);
131 PUTBYTE(val & 0xFF);
132 }
133
134 static void
write_marker(int marker)135 write_marker (int marker)
136 {
137 PUTBYTE(0xFF);
138 PUTBYTE(marker);
139 }
140
141 static void
copy_rest_of_file(void)142 copy_rest_of_file (void)
143 {
144 int c;
145
146 while ((c = NEXTBYTE()) != EOF)
147 PUTBYTE(c);
148 }
149
150
151 /*
152 * JPEG markers consist of one or more 0xFF bytes, followed by a marker
153 * code byte (which is not an FF). Here are the marker codes of interest
154 * in this program. (See jdmarker.c for a more complete list.)
155 */
156
157 #define M_SOF0 0xC0 /* Start Of Frame N */
158 #define M_SOF1 0xC1 /* N indicates which compression process */
159 #define M_SOF2 0xC2 /* Only SOF0-SOF2 are now in common use */
160 #define M_SOF3 0xC3
161 #define M_SOF5 0xC5 /* NB: codes C4 and CC are NOT SOF markers */
162 #define M_SOF6 0xC6
163 #define M_SOF7 0xC7
164 #define M_SOF9 0xC9
165 #define M_SOF10 0xCA
166 #define M_SOF11 0xCB
167 #define M_SOF13 0xCD
168 #define M_SOF14 0xCE
169 #define M_SOF15 0xCF
170 #define M_SOI 0xD8 /* Start Of Image (beginning of datastream) */
171 #define M_EOI 0xD9 /* End Of Image (end of datastream) */
172 #define M_SOS 0xDA /* Start Of Scan (begins compressed data) */
173 #define M_COM 0xFE /* COMment */
174
175
176 /*
177 * Find the next JPEG marker and return its marker code.
178 * We expect at least one FF byte, possibly more if the compressor used FFs
179 * to pad the file. (Padding FFs will NOT be replicated in the output file.)
180 * There could also be non-FF garbage between markers. The treatment of such
181 * garbage is unspecified; we choose to skip over it but emit a warning msg.
182 * NB: this routine must not be used after seeing SOS marker, since it will
183 * not deal correctly with FF/00 sequences in the compressed image data...
184 */
185
186 static int
next_marker(void)187 next_marker (void)
188 {
189 int c;
190 int discarded_bytes = 0;
191
192 /* Find 0xFF byte; count and skip any non-FFs. */
193 c = read_1_byte();
194 while (c != 0xFF) {
195 discarded_bytes++;
196 c = read_1_byte();
197 }
198 /* Get marker code byte, swallowing any duplicate FF bytes. Extra FFs
199 * are legal as pad bytes, so don't count them in discarded_bytes.
200 */
201 do {
202 c = read_1_byte();
203 } while (c == 0xFF);
204
205 if (discarded_bytes != 0) {
206 fprintf(stderr, "Warning: garbage data found in JPEG file\n");
207 }
208
209 return c;
210 }
211
212
213 /*
214 * Read the initial marker, which should be SOI.
215 * For a JFIF file, the first two bytes of the file should be literally
216 * 0xFF M_SOI. To be more general, we could use next_marker, but if the
217 * input file weren't actually JPEG at all, next_marker might read the whole
218 * file and then return a misleading error message...
219 */
220
221 static int
first_marker(void)222 first_marker (void)
223 {
224 int c1, c2;
225
226 c1 = NEXTBYTE();
227 c2 = NEXTBYTE();
228 if (c1 != 0xFF || c2 != M_SOI)
229 ERREXIT("Not a JPEG file");
230 return c2;
231 }
232
233
234 /*
235 * Most types of marker are followed by a variable-length parameter segment.
236 * This routine skips over the parameters for any marker we don't otherwise
237 * want to process.
238 * Note that we MUST skip the parameter segment explicitly in order not to
239 * be fooled by 0xFF bytes that might appear within the parameter segment;
240 * such bytes do NOT introduce new markers.
241 */
242
243 static void
copy_variable(void)244 copy_variable (void)
245 /* Copy an unknown or uninteresting variable-length marker */
246 {
247 unsigned int length;
248
249 /* Get the marker parameter length count */
250 length = read_2_bytes();
251 write_2_bytes(length);
252 /* Length includes itself, so must be at least 2 */
253 if (length < 2)
254 ERREXIT("Erroneous JPEG marker length");
255 length -= 2;
256 /* Skip over the remaining bytes */
257 while (length > 0) {
258 write_1_byte(read_1_byte());
259 length--;
260 }
261 }
262
263 static void
skip_variable(void)264 skip_variable (void)
265 /* Skip over an unknown or uninteresting variable-length marker */
266 {
267 unsigned int length;
268
269 /* Get the marker parameter length count */
270 length = read_2_bytes();
271 /* Length includes itself, so must be at least 2 */
272 if (length < 2)
273 ERREXIT("Erroneous JPEG marker length");
274 length -= 2;
275 /* Skip over the remaining bytes */
276 while (length > 0) {
277 (void) read_1_byte();
278 length--;
279 }
280 }
281
282
283 /*
284 * Parse the marker stream until SOFn or EOI is seen;
285 * copy data to output, but discard COM markers unless keep_COM is true.
286 */
287
288 static int
scan_JPEG_header(int keep_COM)289 scan_JPEG_header (int keep_COM)
290 {
291 int marker;
292
293 /* Expect SOI at start of file */
294 if (first_marker() != M_SOI)
295 ERREXIT("Expected SOI marker first");
296 write_marker(M_SOI);
297
298 /* Scan miscellaneous markers until we reach SOFn. */
299 for (;;) {
300 marker = next_marker();
301 switch (marker) {
302 /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
303 * treated as SOFn. C4 in particular is actually DHT.
304 */
305 case M_SOF0: /* Baseline */
306 case M_SOF1: /* Extended sequential, Huffman */
307 case M_SOF2: /* Progressive, Huffman */
308 case M_SOF3: /* Lossless, Huffman */
309 case M_SOF5: /* Differential sequential, Huffman */
310 case M_SOF6: /* Differential progressive, Huffman */
311 case M_SOF7: /* Differential lossless, Huffman */
312 case M_SOF9: /* Extended sequential, arithmetic */
313 case M_SOF10: /* Progressive, arithmetic */
314 case M_SOF11: /* Lossless, arithmetic */
315 case M_SOF13: /* Differential sequential, arithmetic */
316 case M_SOF14: /* Differential progressive, arithmetic */
317 case M_SOF15: /* Differential lossless, arithmetic */
318 return marker;
319
320 case M_SOS: /* should not see compressed data before SOF */
321 ERREXIT("SOS without prior SOFn");
322 break;
323
324 case M_EOI: /* in case it's a tables-only JPEG stream */
325 return marker;
326
327 case M_COM: /* Existing COM: conditionally discard */
328 if (keep_COM) {
329 write_marker(marker);
330 copy_variable();
331 } else {
332 skip_variable();
333 }
334 break;
335
336 default: /* Anything else just gets copied */
337 write_marker(marker);
338 copy_variable(); /* we assume it has a parameter count... */
339 break;
340 }
341 } /* end loop */
342 }
343
344
345 /* Command line parsing code */
346
347 static const char * progname; /* program name for error messages */
348
349
350 static void
usage(void)351 usage (void)
352 /* complain about bad command line */
353 {
354 fprintf(stderr, "wrjpgcom inserts a textual comment in a JPEG file.\n");
355 fprintf(stderr, "You can add to or replace any existing comment(s).\n");
356
357 fprintf(stderr, "Usage: %s [switches] ", progname);
358 #ifdef TWO_FILE_COMMANDLINE
359 fprintf(stderr, "inputfile outputfile\n");
360 #else
361 fprintf(stderr, "[inputfile]\n");
362 #endif
363
364 fprintf(stderr, "Switches (names may be abbreviated):\n");
365 fprintf(stderr, " -replace Delete any existing comments\n");
366 fprintf(stderr, " -comment \"text\" Insert comment with given text\n");
367 fprintf(stderr, " -cfile name Read comment from named file\n");
368 fprintf(stderr, "Notice that you must put quotes around the comment text\n");
369 fprintf(stderr, "when you use -comment.\n");
370 fprintf(stderr, "If you do not give either -comment or -cfile on the command line,\n");
371 fprintf(stderr, "then the comment text is read from standard input.\n");
372 fprintf(stderr, "It can be multiple lines, up to %u characters total.\n",
373 (unsigned int) MAX_COM_LENGTH);
374 #ifndef TWO_FILE_COMMANDLINE
375 fprintf(stderr, "You must specify an input JPEG file name when supplying\n");
376 fprintf(stderr, "comment text from standard input.\n");
377 #endif
378
379 exit(EXIT_FAILURE);
380 }
381
382
383 static int
keymatch(char * arg,const char * keyword,int minchars)384 keymatch (char * arg, const char * keyword, int minchars)
385 /* Case-insensitive matching of (possibly abbreviated) keyword switches. */
386 /* keyword is the constant keyword (must be lower case already), */
387 /* minchars is length of minimum legal abbreviation. */
388 {
389 register int ca, ck;
390 register int nmatched = 0;
391
392 while ((ca = *arg++) != '\0') {
393 if ((ck = *keyword++) == '\0')
394 return 0; /* arg longer than keyword, no good */
395 if (isupper(ca)) /* force arg to lcase (assume ck is already) */
396 ca = tolower(ca);
397 if (ca != ck)
398 return 0; /* no good */
399 nmatched++; /* count matched characters */
400 }
401 /* reached end of argument; fail if it's too short for unique abbrev */
402 if (nmatched < minchars)
403 return 0;
404 return 1; /* A-OK */
405 }
406
407
408 /*
409 * The main program.
410 */
411
412 int
main(int argc,char ** argv)413 main (int argc, char **argv)
414 {
415 int argn;
416 char * arg;
417 int keep_COM = 1;
418 char * comment_arg = NULL;
419 FILE * comment_file = NULL;
420 unsigned int comment_length = 0;
421 int marker;
422
423 /* On Mac, fetch a command line. */
424 #ifdef USE_CCOMMAND
425 argc = ccommand(&argv);
426 #endif
427
428 progname = argv[0];
429 if (progname == NULL || progname[0] == 0)
430 progname = "wrjpgcom"; /* in case C library doesn't provide it */
431
432 /* Parse switches, if any */
433 for (argn = 1; argn < argc; argn++) {
434 arg = argv[argn];
435 if (arg[0] != '-')
436 break; /* not switch, must be file name */
437 arg++; /* advance over '-' */
438 if (keymatch(arg, "replace", 1)) {
439 keep_COM = 0;
440 } else if (keymatch(arg, "cfile", 2)) {
441 if (++argn >= argc) usage();
442 if ((comment_file = fopen(argv[argn], "r")) == NULL) {
443 fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
444 exit(EXIT_FAILURE);
445 }
446 } else if (keymatch(arg, "comment", 1)) {
447 if (++argn >= argc) usage();
448 comment_arg = argv[argn];
449 /* If the comment text starts with '"', then we are probably running
450 * under MS-DOG and must parse out the quoted string ourselves. Sigh.
451 */
452 if (comment_arg[0] == '"') {
453 comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);
454 if (comment_arg == NULL)
455 ERREXIT("Insufficient memory");
456 strcpy(comment_arg, argv[argn]+1);
457 for (;;) {
458 comment_length = (unsigned int) strlen(comment_arg);
459 if (comment_length > 0 && comment_arg[comment_length-1] == '"') {
460 comment_arg[comment_length-1] = '\0'; /* zap terminating quote */
461 break;
462 }
463 if (++argn >= argc)
464 ERREXIT("Missing ending quote mark");
465 strcat(comment_arg, " ");
466 strcat(comment_arg, argv[argn]);
467 }
468 }
469 comment_length = (unsigned int) strlen(comment_arg);
470 } else
471 usage();
472 }
473
474 /* Cannot use both -comment and -cfile. */
475 if (comment_arg != NULL && comment_file != NULL)
476 usage();
477 /* If there is neither -comment nor -cfile, we will read the comment text
478 * from stdin; in this case there MUST be an input JPEG file name.
479 */
480 if (comment_arg == NULL && comment_file == NULL && argn >= argc)
481 usage();
482
483 /* Open the input file. */
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 */
491 #ifdef USE_SETMODE /* need to hack file mode? */
492 setmode(fileno(stdin), O_BINARY);
493 #endif
494 #ifdef USE_FDOPEN /* need to re-open in binary mode? */
495 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 /* Open the output file. */
505 #ifdef TWO_FILE_COMMANDLINE
506 /* Must have explicit output file name */
507 if (argn != argc-2) {
508 fprintf(stderr, "%s: must name one input and one output file\n",
509 progname);
510 usage();
511 }
512 if ((outfile = fopen(argv[argn+1], WRITE_BINARY)) == NULL) {
513 fprintf(stderr, "%s: can't open %s\n", progname, argv[argn+1]);
514 exit(EXIT_FAILURE);
515 }
516 #else
517 /* Unix style: expect zero or one file name */
518 if (argn < argc-1) {
519 fprintf(stderr, "%s: only one input file\n", progname);
520 usage();
521 }
522 /* default output file is stdout */
523 #ifdef USE_SETMODE /* need to hack file mode? */
524 setmode(fileno(stdout), O_BINARY);
525 #endif
526 #ifdef USE_FDOPEN /* need to re-open in binary mode? */
527 if ((outfile = fdopen(fileno(stdout), WRITE_BINARY)) == NULL) {
528 fprintf(stderr, "%s: can't open stdout\n", progname);
529 exit(EXIT_FAILURE);
530 }
531 #else
532 outfile = stdout;
533 #endif
534 #endif /* TWO_FILE_COMMANDLINE */
535
536 /* Collect comment text from comment_file or stdin, if necessary */
537 if (comment_arg == NULL) {
538 FILE * src_file;
539 int c;
540
541 comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);
542 if (comment_arg == NULL)
543 ERREXIT("Insufficient memory");
544 comment_length = 0;
545 src_file = (comment_file != NULL ? comment_file : stdin);
546 while ((c = getc(src_file)) != EOF) {
547 if (comment_length >= (unsigned int) MAX_COM_LENGTH) {
548 fprintf(stderr, "Comment text may not exceed %u bytes\n",
549 (unsigned int) MAX_COM_LENGTH);
550 exit(EXIT_FAILURE);
551 }
552 comment_arg[comment_length++] = (char) c;
553 }
554 if (comment_file != NULL)
555 fclose(comment_file);
556 }
557
558 /* Copy JPEG headers until SOFn marker;
559 * we will insert the new comment marker just before SOFn.
560 * This (a) causes the new comment to appear after, rather than before,
561 * existing comments; and (b) ensures that comments come after any JFIF
562 * or JFXX markers, as required by the JFIF specification.
563 */
564 marker = scan_JPEG_header(keep_COM);
565 /* Insert the new COM marker, but only if nonempty text has been supplied */
566 if (comment_length > 0) {
567 write_marker(M_COM);
568 write_2_bytes(comment_length + 2);
569 while (comment_length > 0) {
570 write_1_byte(*comment_arg++);
571 comment_length--;
572 }
573 }
574 /* Duplicate the remainder of the source file.
575 * Note that any COM markers occuring after SOF will not be touched.
576 */
577 write_marker(marker);
578 copy_rest_of_file();
579
580 /* All done. */
581 exit(EXIT_SUCCESS);
582 return 0; /* suppress no-return-value warnings */
583 }
584