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rdjpgcom.c
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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 
65 static 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 */
76 static int
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 */
89 static unsigned int
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 
141 static int
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 
176 static int
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 
198 static 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 
224 static void
225 process_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 
281 static void
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();
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 
339 static int
340 scan_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)
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 
405 static const char * progname; /* program name for error messages */
406 
407 
408 static void
409 usage (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 
421 }
422 
423 
424 static int
425 keymatch (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 
453 int
454 main (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]);
493  }
494  } else {
495  /* default input file is stdin */
496 #ifdef USE_SETMODE /* need to hack file mode? */
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);
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. */
514  return 0; /* suppress no-return-value warnings */
515 }
static void skip_variable(void)
Definition: rdjpgcom.c:199
static int argc
Definition: ServiceArgs.c:12
#define LC_CTYPE
Definition: locale.h:27
#define M_SOF6
Definition: rdjpgcom.c:115
static void process_COM(int raw)
Definition: rdjpgcom.c:225
static int keymatch(char *arg, const char *keyword, int minchars)
Definition: rdjpgcom.c:425
struct png_info_def **typedef void(__cdecl typeof(png_destroy_read_struct))(struct png_struct_def **
Definition: typeof.h:49
#define ERREXIT(msg)
Definition: rdjpgcom.c:72
static int first_marker(void)
Definition: rdjpgcom.c:177
#define M_SOF2
Definition: rdjpgcom.c:112
#define M_SOF1
Definition: rdjpgcom.c:111
static HANDLE process
Definition: process.c:76
#define M_SOF0
Definition: rdjpgcom.c:110
static FILE * infile
Definition: rdjpgcom.c:65
FILE * stdin
void * arg
Definition: msvc.h:12
static int read_1_byte(void)
Definition: rdjpgcom.c:77
#define M_SOF7
Definition: rdjpgcom.c:116
static unsigned int read_2_bytes(void)
Definition: rdjpgcom.c:90
#define argv
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int main(int argc, char **argv)
Definition: rdjpgcom.c:454
#define M_SOF3
Definition: rdjpgcom.c:113
int image_height
#define M_EOI
Definition: rdjpgcom.c:124
FILE * stdout
#define verbose
Definition: rosglue.h:36
#define EXIT_SUCCESS
Definition: rdjpgcom.c:55
_Check_return_opt_ _CRTIMP int __cdecl fprintf(_Inout_ FILE *_File, _In_z_ _Printf_format_string_ const char *_Format,...)
static int next_marker(void)
Definition: rdjpgcom.c:142
int image_width
#define M_SOF5
Definition: rdjpgcom.c:114
smooth NULL
Definition: ftsmooth.c:416
static void usage(void)
Definition: rdjpgcom.c:409
int marker
Definition: jpeglib.h:1027
#define M_SOF10
Definition: rdjpgcom.c:118
#define READ_BINARY
Definition: rdjpgcom.c:44
const char int minchars
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_Check_return_opt_ _CRTIMP int __cdecl putc(_In_ int _Ch, _Inout_ FILE *_File)
_Check_return_ _CRTIMP int __cdecl fileno(_In_ FILE *_File)
#define isupper(c)
Definition: acclib.h:71
GLenum GLuint GLenum GLsizei length
Definition: glext.h:5579
#define EXIT_FAILURE
Definition: rdjpgcom.c:49
const GLubyte * c
Definition: glext.h:8905
#define NEXTBYTE()
Definition: rdjpgcom.c:68
#define M_SOF13
Definition: rdjpgcom.c:120
_Check_return_ _CRTIMP FILE *__cdecl fopen(_In_z_ const char *_Filename, _In_z_ const char *_Mode)
_Check_return_ _CRTIMP int __cdecl setmode(_In_ int _FileHandle, _In_ int _Mode)
#define M_APP12
Definition: rdjpgcom.c:127
#define M_SOF11
Definition: rdjpgcom.c:119
static void process_SOFn(int marker)
Definition: rdjpgcom.c:282
#define O_BINARY
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_Check_return_ _CRTIMP FILE *__cdecl fdopen(_In_ int _FileHandle, _In_z_ const char *_Format)
#define M_SOS
Definition: rdjpgcom.c:125
#define isprint(c)
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#define M_SOF14
Definition: rdjpgcom.c:121
#define EOF
Definition: stdio.h:24
#define M_SOF15
Definition: rdjpgcom.c:122
#define M_SOF9
Definition: rdjpgcom.c:117
#define c
Definition: ke_i.h:80
#define M_COM
Definition: rdjpgcom.c:128
FILE * stderr
#define setlocale(n, s)
Definition: locale.h:46
#define M_SOI
Definition: rdjpgcom.c:123
static const char * progname
Definition: rdjpgcom.c:405
void exit(int exitcode)
Definition: _exit.c:33
static const WCHAR ca[]
Definition: main.c:457
int tolower(int c)
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#define printf
Definition: config.h:203
unsigned int(__cdecl typeof(jpeg_read_scanlines))(struct jpeg_decompress_struct *
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static int scan_JPEG_header(int verbose, int raw)
Definition: rdjpgcom.c:340