1
2 /* pngerror.c - stub functions for i/o and memory allocation
3 *
4 * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
5 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file provides a location for all error handling. Users who
14 * need special error handling are expected to write replacement functions
15 * and use png_set_error_fn() to use those functions. See the instructions
16 * at each function.
17 */
18
19 #include "pngpriv.h"
20 #define PNG_SRC_FILE PNG_SRC_FILE_pngerror
21
22 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
23
24 static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
25 png_const_charp error_message)),PNG_NORETURN);
26
27 #ifdef PNG_WARNINGS_SUPPORTED
28 static void /* PRIVATE */
29 png_default_warning PNGARG((png_const_structrp png_ptr,
30 png_const_charp warning_message));
31 #endif /* WARNINGS */
32
33 /* This function is called whenever there is a fatal error. This function
34 * should not be changed. If there is a need to handle errors differently,
35 * you should supply a replacement error function and use png_set_error_fn()
36 * to replace the error function at run-time.
37 */
38 #ifdef PNG_ERROR_TEXT_SUPPORTED
39 PNG_FUNCTION(void,PNGAPI
40 png_error,(png_const_structrp png_ptr, png_const_charp error_message),
41 PNG_NORETURN)
42 {
43 if (png_ptr != NULL && png_ptr->error_fn != NULL)
44 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),
45 error_message);
46
47 /* If the custom handler doesn't exist, or if it returns,
48 use the default handler, which will not return. */
49 png_default_error(png_ptr, error_message);
50 }
51 #else
52 PNG_FUNCTION(void,PNGAPI
53 png_err,(png_const_structrp png_ptr),PNG_NORETURN)
54 {
55 /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
56 * erroneously as '\0', instead of the empty string "". This was
57 * apparently an error, introduced in libpng-1.2.20, and png_default_error
58 * will crash in this case.
59 */
60 if (png_ptr != NULL && png_ptr->error_fn != NULL)
61 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");
62
63 /* If the custom handler doesn't exist, or if it returns,
64 use the default handler, which will not return. */
65 png_default_error(png_ptr, "");
66 }
67 #endif /* ERROR_TEXT */
68
69 /* Utility to safely appends strings to a buffer. This never errors out so
70 * error checking is not required in the caller.
71 */
72 size_t
png_safecat(png_charp buffer,size_t bufsize,size_t pos,png_const_charp string)73 png_safecat(png_charp buffer, size_t bufsize, size_t pos,
74 png_const_charp string)
75 {
76 if (buffer != NULL && pos < bufsize)
77 {
78 if (string != NULL)
79 while (*string != '\0' && pos < bufsize-1)
80 buffer[pos++] = *string++;
81
82 buffer[pos] = '\0';
83 }
84
85 return pos;
86 }
87
88 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
89 /* Utility to dump an unsigned value into a buffer, given a start pointer and
90 * and end pointer (which should point just *beyond* the end of the buffer!)
91 * Returns the pointer to the start of the formatted string.
92 */
93 #define PNG_HAVE_FORMAT_NUMBER /* for the code below */
94 png_charp
png_format_number(png_const_charp start,png_charp end,int format,png_alloc_size_t number)95 png_format_number(png_const_charp start, png_charp end, int format,
96 png_alloc_size_t number)
97 {
98 int count = 0; /* number of digits output */
99 int mincount = 1; /* minimum number required */
100 int output = 0; /* digit output (for the fixed point format) */
101
102 *--end = '\0';
103
104 /* This is written so that the loop always runs at least once, even with
105 * number zero.
106 */
107 while (end > start && (number != 0 || count < mincount))
108 {
109
110 static const char digits[] = "0123456789ABCDEF";
111
112 switch (format)
113 {
114 case PNG_NUMBER_FORMAT_fixed:
115 /* Needs five digits (the fraction) */
116 mincount = 5;
117 if (output != 0 || number % 10 != 0)
118 {
119 *--end = digits[number % 10];
120 output = 1;
121 }
122 number /= 10;
123 break;
124
125 case PNG_NUMBER_FORMAT_02u:
126 /* Expects at least 2 digits. */
127 mincount = 2;
128 /* FALL THROUGH */
129
130 case PNG_NUMBER_FORMAT_u:
131 *--end = digits[number % 10];
132 number /= 10;
133 break;
134
135 case PNG_NUMBER_FORMAT_02x:
136 /* This format expects at least two digits */
137 mincount = 2;
138 /* FALL THROUGH */
139
140 case PNG_NUMBER_FORMAT_x:
141 *--end = digits[number & 0xf];
142 number >>= 4;
143 break;
144
145 default: /* an error */
146 number = 0;
147 break;
148 }
149
150 /* Keep track of the number of digits added */
151 ++count;
152
153 /* Float a fixed number here: */
154 if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
155 {
156 /* End of the fraction, but maybe nothing was output? In that case
157 * drop the decimal point. If the number is a true zero handle that
158 * here.
159 */
160 if (output != 0)
161 *--end = '.';
162 else if (number == 0) /* and !output */
163 *--end = '0';
164 }
165 }
166
167 return end;
168 }
169 #endif
170
171 #ifdef PNG_WARNINGS_SUPPORTED
172 /* This function is called whenever there is a non-fatal error. This function
173 * should not be changed. If there is a need to handle warnings differently,
174 * you should supply a replacement warning function and use
175 * png_set_error_fn() to replace the warning function at run-time.
176 */
177 void PNGAPI
png_warning(png_const_structrp png_ptr,png_const_charp warning_message)178 png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
179 {
180 int offset = 0;
181 if (png_ptr != NULL && png_ptr->warning_fn != NULL)
182 (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
183 warning_message + offset);
184 else
185 png_default_warning(png_ptr, warning_message + offset);
186 }
187
188 /* These functions support 'formatted' warning messages with up to
189 * PNG_WARNING_PARAMETER_COUNT parameters. In the format string the parameter
190 * is introduced by @<number>, where 'number' starts at 1. This follows the
191 * standard established by X/Open for internationalizable error messages.
192 */
193 void
png_warning_parameter(png_warning_parameters p,int number,png_const_charp string)194 png_warning_parameter(png_warning_parameters p, int number,
195 png_const_charp string)
196 {
197 if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
198 (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
199 }
200
201 void
png_warning_parameter_unsigned(png_warning_parameters p,int number,int format,png_alloc_size_t value)202 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
203 png_alloc_size_t value)
204 {
205 char buffer[PNG_NUMBER_BUFFER_SIZE];
206 png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
207 }
208
209 void
png_warning_parameter_signed(png_warning_parameters p,int number,int format,png_int_32 value)210 png_warning_parameter_signed(png_warning_parameters p, int number, int format,
211 png_int_32 value)
212 {
213 png_alloc_size_t u;
214 png_charp str;
215 char buffer[PNG_NUMBER_BUFFER_SIZE];
216
217 /* Avoid overflow by doing the negate in a png_alloc_size_t: */
218 u = (png_alloc_size_t)value;
219 if (value < 0)
220 u = ~u + 1;
221
222 str = PNG_FORMAT_NUMBER(buffer, format, u);
223
224 if (value < 0 && str > buffer)
225 *--str = '-';
226
227 png_warning_parameter(p, number, str);
228 }
229
230 void
png_formatted_warning(png_const_structrp png_ptr,png_warning_parameters p,png_const_charp message)231 png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
232 png_const_charp message)
233 {
234 /* The internal buffer is just 192 bytes - enough for all our messages,
235 * overflow doesn't happen because this code checks! If someone figures
236 * out how to send us a message longer than 192 bytes, all that will
237 * happen is that the message will be truncated appropriately.
238 */
239 size_t i = 0; /* Index in the msg[] buffer: */
240 char msg[192];
241
242 /* Each iteration through the following loop writes at most one character
243 * to msg[i++] then returns here to validate that there is still space for
244 * the trailing '\0'. It may (in the case of a parameter) read more than
245 * one character from message[]; it must check for '\0' and continue to the
246 * test if it finds the end of string.
247 */
248 while (i<(sizeof msg)-1 && *message != '\0')
249 {
250 /* '@' at end of string is now just printed (previously it was skipped);
251 * it is an error in the calling code to terminate the string with @.
252 */
253 if (p != NULL && *message == '@' && message[1] != '\0')
254 {
255 int parameter_char = *++message; /* Consume the '@' */
256 static const char valid_parameters[] = "123456789";
257 int parameter = 0;
258
259 /* Search for the parameter digit, the index in the string is the
260 * parameter to use.
261 */
262 while (valid_parameters[parameter] != parameter_char &&
263 valid_parameters[parameter] != '\0')
264 ++parameter;
265
266 /* If the parameter digit is out of range it will just get printed. */
267 if (parameter < PNG_WARNING_PARAMETER_COUNT)
268 {
269 /* Append this parameter */
270 png_const_charp parm = p[parameter];
271 png_const_charp pend = p[parameter] + (sizeof p[parameter]);
272
273 /* No need to copy the trailing '\0' here, but there is no guarantee
274 * that parm[] has been initialized, so there is no guarantee of a
275 * trailing '\0':
276 */
277 while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
278 msg[i++] = *parm++;
279
280 /* Consume the parameter digit too: */
281 ++message;
282 continue;
283 }
284
285 /* else not a parameter and there is a character after the @ sign; just
286 * copy that. This is known not to be '\0' because of the test above.
287 */
288 }
289
290 /* At this point *message can't be '\0', even in the bad parameter case
291 * above where there is a lone '@' at the end of the message string.
292 */
293 msg[i++] = *message++;
294 }
295
296 /* i is always less than (sizeof msg), so: */
297 msg[i] = '\0';
298
299 /* And this is the formatted message. It may be larger than
300 * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
301 * are not (currently) formatted.
302 */
303 png_warning(png_ptr, msg);
304 }
305 #endif /* WARNINGS */
306
307 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
308 void PNGAPI
png_benign_error(png_const_structrp png_ptr,png_const_charp error_message)309 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
310 {
311 switch (png_ptr->benign_error_action)
312 {
313 case PNG_ERROR:
314 png_chunk_error(png_ptr, error_message);
315 break;
316
317 case PNG_WARN:
318 png_chunk_warning(png_ptr, error_message);
319 break;
320
321 default: /* PNG_IGNORE */
322 break;
323 }
324
325 # ifndef PNG_ERROR_TEXT_SUPPORTED
326 PNG_UNUSED(error_message)
327 # endif
328 }
329
330 static void
app_error(png_const_structrp png_ptr,png_const_charp error_message,unsigned int error_action)331 app_error(png_const_structrp png_ptr, png_const_charp error_message,
332 unsigned int error_action)
333 {
334 switch (error_action)
335 {
336 case PNG_ERROR:
337 png_error(png_ptr, error_message);
338 break;
339
340 case PNG_WARN:
341 png_warning(png_ptr, error_message);
342 break;
343
344 default: /* PNG_IGNORE */
345 break;
346 }
347
348 # ifndef PNG_ERROR_TEXT_SUPPORTED
349 PNG_UNUSED(error_message)
350 # endif
351 }
352
353 void /* PRIVATE */
png_app_warning(png_const_structrp png_ptr,png_const_charp error_message)354 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
355 {
356 app_error(png_ptr, error_message, png_ptr->app_warning_action);
357 }
358
359 void /* PRIVATE */
png_app_error(png_const_structrp png_ptr,png_const_charp error_message)360 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
361 {
362 app_error(png_ptr, error_message, png_ptr->app_error_action);
363 }
364 #endif /* BENIGN_ERRORS */
365
366 #define PNG_MAX_ERROR_TEXT 196 /* Currently limited by profile_error in png.c */
367 #if defined(PNG_WARNINGS_SUPPORTED) || \
368 (defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))
369 /* These utilities are used internally to build an error message that relates
370 * to the current chunk. The chunk name comes from png_ptr->chunk_name unless
371 * png_ptr->zowner is set in which case that is used in preference. This is
372 * used to prefix the message. The message is limited in length to 63 bytes.
373 * The name characters are output as hex digits wrapped in [] if the character
374 * is invalid.
375 *
376 * Using 'zowner' means that IDAT errors at the end of the IDAT stream are still
377 * reported as from the IDAT chunks.
378 */
379 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
380 static PNG_CONST char png_digit[16] = {
381 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
382 'A', 'B', 'C', 'D', 'E', 'F'
383 };
384
385 static void /* PRIVATE */
png_format_buffer(png_const_structrp png_ptr,png_charp buffer,png_const_charp error_message)386 png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
387 error_message)
388 {
389 png_uint_32 chunk_name = png_ptr->zowner;
390 int iout = 0, ishift = 24;
391
392 if (chunk_name == 0)
393 chunk_name = png_ptr->chunk_name;
394
395 while (ishift >= 0)
396 {
397 int c = (int)(chunk_name >> ishift) & 0xff;
398
399 ishift -= 8;
400 if (isnonalpha(c) != 0)
401 {
402 buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
403 buffer[iout++] = png_digit[(c & 0xf0) >> 4];
404 buffer[iout++] = png_digit[c & 0x0f];
405 buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
406 }
407
408 else
409 {
410 buffer[iout++] = png_check_char(png_ptr, c);
411 }
412 }
413
414 if (error_message == NULL)
415 buffer[iout] = '\0';
416
417 else
418 {
419 int iin = 0;
420
421 buffer[iout++] = ':';
422 buffer[iout++] = ' ';
423
424 while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
425 buffer[iout++] = error_message[iin++];
426
427 /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
428 buffer[iout] = '\0';
429 }
430 }
431 #endif /* WARNINGS || ERROR_TEXT */
432
433 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
434 PNG_FUNCTION(void,PNGAPI
435 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
436 PNG_NORETURN)
437 {
438 char msg[18+PNG_MAX_ERROR_TEXT];
439 if (png_ptr == NULL || png_ptr->chunk_name == 0U)
440 png_error(png_ptr, error_message);
441
442 else
443 {
444 png_format_buffer(png_ptr, msg, error_message);
445 png_error(png_ptr, msg);
446 }
447 }
448 #endif /* READ && ERROR_TEXT */
449
450 #ifdef PNG_WARNINGS_SUPPORTED
451 void PNGAPI
png_chunk_warning(png_const_structrp png_ptr,png_const_charp warning_message)452 png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
453 {
454 char msg[18+PNG_MAX_ERROR_TEXT];
455 if (png_ptr == NULL || png_ptr->chunk_name == 0U)
456 png_warning(png_ptr, warning_message);
457
458 else
459 {
460 png_format_buffer(png_ptr, msg, warning_message);
461 png_warning(png_ptr, msg);
462 }
463 }
464 #endif /* WARNINGS */
465
466 #ifdef PNG_READ_SUPPORTED
467 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
468 void PNGAPI
png_chunk_benign_error(png_const_structrp png_ptr,png_const_charp error_message)469 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
470 error_message)
471 {
472 switch (png_ptr->benign_error_action)
473 {
474 case PNG_ERROR:
475 png_chunk_error(png_ptr, error_message);
476 break;
477
478 case PNG_WARN:
479 png_chunk_warning(png_ptr, error_message);
480 break;
481
482 default: /* PNG_IGNORE */
483 break;
484 }
485
486 # ifndef PNG_ERROR_TEXT_SUPPORTED
487 PNG_UNUSED(error_message)
488 # endif
489 }
490 #endif /* BENIGN_ERRORS */
491 #endif /* READ */
492
493 void /* PRIVATE */
494 (png_chunk_report)(png_const_structrp png_ptr, png_const_charp message,
495 int error)
496 {
497 /* This is always supported, but for just read or just write it
498 * unconditionally does the right thing.
499 */
500 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
501 if (png_ptr->read_struct)
502 # endif
503
504 # ifdef PNG_READ_SUPPORTED
505 {
506 if (error < PNG_CHUNK_ERROR)
507 png_chunk_warning(png_ptr, message);
508
509 else if (error < PNG_CHUNK_FATAL)
510 png_chunk_benign_error(png_ptr, message);
511
512 else
513 png_chunk_error(png_ptr, message);
514 }
515 # endif
516
517 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
518 else if (!png_ptr->read_struct)
519 # endif
520
521 # ifdef PNG_WRITE_SUPPORTED
522 {
523 if (error < PNG_CHUNK_WRITE_ERROR)
524 png_app_warning(png_ptr, message);
525
526 else if (error < PNG_CHUNK_FATAL)
527 png_app_error(png_ptr, message);
528
529 else
530 png_error(png_ptr, message);
531 }
532 # endif
533
534 # ifndef PNG_ERROR_TEXT_SUPPORTED
535 PNG_UNUSED(message)
536 # endif
537 }
538
539 #ifdef PNG_ERROR_TEXT_SUPPORTED
540
541 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
542 (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
543 defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
544 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
545 (defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) &&\
546 defined(PNG_sCAL_SUPPORTED))
547 PNG_FUNCTION(void,
548 png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
549 {
550 # define fixed_message "fixed point overflow in "
551 # define fixed_message_ln ((sizeof fixed_message)-1)
552 int iin;
553 char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
554 memcpy(msg, fixed_message, fixed_message_ln);
555 iin = 0;
556 if (name != NULL)
557 while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
558 {
559 msg[fixed_message_ln + iin] = name[iin];
560 ++iin;
561 }
562 msg[fixed_message_ln + iin] = 0;
563 png_error(png_ptr, msg);
564 }
565 #endif
566 #endif
567
568 #ifdef PNG_SETJMP_SUPPORTED
569 /* This API only exists if ANSI-C style error handling is used,
570 * otherwise it is necessary for png_default_error to be overridden.
571 */
572 jmp_buf* PNGAPI
png_set_longjmp_fn(png_structrp png_ptr,png_longjmp_ptr longjmp_fn,size_t jmp_buf_size)573 png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
574 size_t jmp_buf_size)
575 {
576 /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
577 * and it must not change after that. Libpng doesn't care how big the
578 * buffer is, just that it doesn't change.
579 *
580 * If the buffer size is no *larger* than the size of jmp_buf when libpng is
581 * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
582 * semantics that this call will not fail. If the size is larger, however,
583 * the buffer is allocated and this may fail, causing the function to return
584 * NULL.
585 */
586 if (png_ptr == NULL)
587 return NULL;
588
589 if (png_ptr->jmp_buf_ptr == NULL)
590 {
591 png_ptr->jmp_buf_size = 0; /* not allocated */
592
593 if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
594 png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
595
596 else
597 {
598 png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
599 png_malloc_warn(png_ptr, jmp_buf_size));
600
601 if (png_ptr->jmp_buf_ptr == NULL)
602 return NULL; /* new NULL return on OOM */
603
604 png_ptr->jmp_buf_size = jmp_buf_size;
605 }
606 }
607
608 else /* Already allocated: check the size */
609 {
610 size_t size = png_ptr->jmp_buf_size;
611
612 if (size == 0)
613 {
614 size = (sizeof png_ptr->jmp_buf_local);
615 if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
616 {
617 /* This is an internal error in libpng: somehow we have been left
618 * with a stack allocated jmp_buf when the application regained
619 * control. It's always possible to fix this up, but for the moment
620 * this is an affirm because that makes it easy to detect.
621 */
622 impossible("Libpng jmp_buf still allocated");
623 /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
624 }
625 }
626
627 if (size != jmp_buf_size)
628 {
629 png_warning(png_ptr, "Application jmp_buf size changed");
630 return NULL; /* caller will probably crash: no choice here */
631 }
632 }
633
634 /* Finally fill in the function, now we have a satisfactory buffer. It is
635 * valid to change the function on every call.
636 */
637 png_ptr->longjmp_fn = longjmp_fn;
638 return png_ptr->jmp_buf_ptr;
639 }
640
641 void /* PRIVATE */
png_free_jmpbuf(png_structrp png_ptr)642 png_free_jmpbuf(png_structrp png_ptr)
643 {
644 if (png_ptr != NULL)
645 {
646 jmp_buf *jb = png_ptr->jmp_buf_ptr;
647
648 /* A size of 0 is used to indicate a local, stack, allocation of the
649 * pointer; used here and in png.c
650 */
651 if (jb != NULL && png_ptr->jmp_buf_size > 0)
652 {
653
654 /* This stuff is so that a failure to free the error control structure
655 * does not leave libpng in a state with no valid error handling: the
656 * free always succeeds, if there is an error it gets ignored.
657 */
658 if (jb != &png_ptr->jmp_buf_local)
659 {
660 /* Make an internal, libpng, jmp_buf to return here */
661 jmp_buf free_jmp_buf;
662
663 if (!setjmp(free_jmp_buf))
664 {
665 png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
666 png_ptr->jmp_buf_size = 0; /* stack allocation */
667 png_ptr->longjmp_fn = longjmp;
668 png_free(png_ptr, jb); /* Return to setjmp on error */
669 }
670 }
671 }
672
673 /* *Always* cancel everything out: */
674 png_ptr->jmp_buf_size = 0;
675 png_ptr->jmp_buf_ptr = NULL;
676 png_ptr->longjmp_fn = 0;
677 }
678 }
679 #endif
680
681 /* This is the default error handling function. Note that replacements for
682 * this function MUST NOT RETURN, or the program will likely crash. This
683 * function is used by default, or if the program supplies NULL for the
684 * error function pointer in png_set_error_fn().
685 */
686 static PNG_FUNCTION(void /* PRIVATE */,
687 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
688 PNG_NORETURN)
689 {
690 #ifdef PNG_CONSOLE_IO_SUPPORTED
691 {
692 fprintf(stderr, "libpng error: %s", error_message ? error_message :
693 "undefined");
694 fprintf(stderr, PNG_STRING_NEWLINE);
695 }
696 #else
697 PNG_UNUSED(error_message) /* Make compiler happy */
698 #endif
699 png_longjmp(png_ptr, 1);
700 }
701
702 PNG_FUNCTION(void,PNGAPI
703 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
704 {
705 #ifdef PNG_SETJMP_SUPPORTED
706 if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
707 png_ptr->jmp_buf_ptr != NULL)
708 png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
709 #else
710 PNG_UNUSED(png_ptr)
711 PNG_UNUSED(val)
712 #endif
713
714 /* If control reaches this point, png_longjmp() must not return. The only
715 * choice is to terminate the whole process (or maybe the thread); to do
716 * this the ANSI-C abort() function is used unless a different method is
717 * implemented by overriding the default configuration setting for
718 * PNG_ABORT (see scripts/pnglibconf.dfa).
719 *
720 * API change: prior to 1.7.0 PNG_ABORT was invoked as a function type macro
721 * with no arguments 'PNG_ABORT();', in 1.7.0 this is changed to a simple
722 * macro that is defined in the configuration.
723 */
724 PNG_ABORT
725 }
726
727 #ifdef PNG_WARNINGS_SUPPORTED
728 /* This function is called when there is a warning, but the library thinks
729 * it can continue anyway. Replacement functions don't have to do anything
730 * here if you don't want them to. In the default configuration, png_ptr is
731 * not used, but it is passed in case it may be useful.
732 */
733 static void /* PRIVATE */
png_default_warning(png_const_structrp png_ptr,png_const_charp warning_message)734 png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
735 {
736 #ifdef PNG_CONSOLE_IO_SUPPORTED
737 {
738 fprintf(stderr, "libpng warning: %s", warning_message);
739 fprintf(stderr, PNG_STRING_NEWLINE);
740 }
741 #else
742 PNG_UNUSED(warning_message) /* Make compiler happy */
743 #endif
744 PNG_UNUSED(png_ptr) /* Make compiler happy */
745 }
746 #endif /* WARNINGS */
747
748 /* This function is called when the application wants to use another method
749 * of handling errors and warnings. Note that the error function MUST NOT
750 * return to the calling routine or serious problems will occur. The return
751 * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
752 */
753 void PNGAPI
png_set_error_fn(png_structrp png_ptr,png_voidp error_ptr,png_error_ptr error_fn,png_error_ptr warning_fn)754 png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
755 png_error_ptr error_fn, png_error_ptr warning_fn)
756 {
757 if (png_ptr == NULL)
758 return;
759
760 png_ptr->error_ptr = error_ptr;
761 png_ptr->error_fn = error_fn;
762 #ifdef PNG_WARNINGS_SUPPORTED
763 png_ptr->warning_fn = warning_fn;
764 #else
765 PNG_UNUSED(warning_fn)
766 #endif
767 }
768
769
770 /* This function returns a pointer to the error_ptr associated with the user
771 * functions. The application should free any memory associated with this
772 * pointer before png_write_destroy and png_read_destroy are called.
773 */
774 png_voidp PNGAPI
png_get_error_ptr(png_const_structrp png_ptr)775 png_get_error_ptr(png_const_structrp png_ptr)
776 {
777 if (png_ptr == NULL)
778 return NULL;
779
780 return ((png_voidp)png_ptr->error_ptr);
781 }
782
783
784 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
785 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
786 /* Currently the above both depend on SETJMP_SUPPORTED, however it would be
787 * possible to implement without setjmp support just so long as there is some
788 * way to handle the error return here:
789 */
790 PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
791 png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
792 PNG_NORETURN)
793 {
794 const png_const_structrp png_ptr = png_nonconst_ptr;
795 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
796
797 /* An error is always logged here, overwriting anything (typically a warning)
798 * that is already there:
799 */
800 if (image != NULL)
801 {
802 png_safecat(image->message, (sizeof image->message), 0, error_message);
803 image->warning_or_error |= PNG_IMAGE_ERROR;
804
805 /* Retrieve the jmp_buf from within the png_control, making this work for
806 * C++ compilation too is pretty tricky: C++ wants a pointer to the first
807 * element of a jmp_buf, but C doesn't tell us the type of that.
808 */
809 if (image->opaque != NULL && image->opaque->error_buf != NULL)
810 longjmp(png_control_jmp_buf(image->opaque), 1);
811
812 /* Missing longjmp buffer, the following is to help debugging: */
813 {
814 size_t pos = png_safecat(image->message, (sizeof image->message), 0,
815 "bad longjmp: ");
816 png_safecat(image->message, (sizeof image->message), pos,
817 error_message);
818 }
819 }
820
821 /* Here on an internal programming error. */
822 abort();
823 }
824
825 #ifdef PNG_WARNINGS_SUPPORTED
826 void /* PRIVATE */ PNGCBAPI
png_safe_warning(png_structp png_nonconst_ptr,png_const_charp warning_message)827 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
828 {
829 const png_const_structrp png_ptr = png_nonconst_ptr;
830 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
831
832 /* A warning is only logged if there is no prior warning or error. */
833 if (image->warning_or_error == 0)
834 {
835 png_safecat(image->message, (sizeof image->message), 0, warning_message);
836 image->warning_or_error |= PNG_IMAGE_WARNING;
837 }
838 }
839 #endif
840
841 int /* PRIVATE */
png_safe_execute(png_imagep image_in,int (* function)(png_voidp),png_voidp arg)842 png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
843 {
844 volatile png_imagep image = image_in;
845 volatile int result;
846 volatile png_voidp saved_error_buf;
847 jmp_buf safe_jmpbuf;
848
849 /* Safely execute function(arg) with png_error returning to this function. */
850 saved_error_buf = image->opaque->error_buf;
851 result = setjmp(safe_jmpbuf) == 0;
852
853 if (result != 0)
854 {
855
856 image->opaque->error_buf = safe_jmpbuf;
857 result = function(arg);
858 }
859
860 image->opaque->error_buf = saved_error_buf;
861
862 /* And do the cleanup prior to any failure return. */
863 if (result == 0)
864 png_image_free(image);
865
866 return result;
867 }
868 #endif /* SIMPLIFIED READ || SIMPLIFIED_WRITE */
869
870 /* Affirms: minimal code in 'STABLE' builds to return control to the
871 * application via png_error(), more verbose code followed by PNG_ABORT for
872 * all other builds to ensure that internal errors are detected.
873 *
874 * The code always produces a message if it is possible, regardless of the
875 * setting of PNG_ERROR_TEXT_SUPPORTED, except that in stable builds
876 * PNG_ERROR_TEXT_SUPPORTED is honored. See pngpriv.h for the calculation of
877 * the two control macros PNG_RELEASE_BUILD (don't abort; stable build or rc)
878 * and PNG_AFFIRM_TEXT (output text.)
879 */
880 #if PNG_AFFIRM_TEXT
881 # ifdef PNG_HAVE_FORMAT_NUMBER
882 static size_t
png_affirm_number(png_charp buffer,size_t bufsize,size_t pos,unsigned int number,int format)883 png_affirm_number(png_charp buffer, size_t bufsize, size_t pos,
884 unsigned int number, int format)
885 {
886 char numbuf[PNG_NUMBER_BUFFER_SIZE];
887 return png_safecat(buffer, bufsize, pos,
888 png_format_number(numbuf, numbuf + sizeof numbuf, format, number));
889 }
890 # define affirm_number(a,b,c,d,e) png_affirm_number(a,b,c,d,e)
891 # else /* !HAVE_FORMAT_NUMBER */
892 static size_t
png_affirm_number(png_charp buffer,size_t bufsize,size_t pos,unsigned int number)893 png_affirm_number(png_charp buffer, size_t bufsize, size_t pos,
894 unsigned int number)
895 {
896 /* binhex it; highly non-portable, assumes the ASCII character set, but
897 * if warnings are turned off then it is unlikely the text will get read
898 * anyway. This binhex variant is (48+val), where 'val' is the next 6
899 * bits of the number, so it starts as '0' (for 0) and ends at 'I' for
900 * 63. The number is wrapped in {}, so 0 comes out as '{}' and 9 comes
901 * out as '{9}' and so on.
902 */
903 char numbuf[32];
904 int i = sizeof numbuf;
905
906 numbuf[--i] = 0;
907 numbuf[--i] = '}';
908
909 do
910 {
911 if (number > 0)
912 numbuf[--i] = (char)/*SAFE*/((number & 63) + 48), number >>= 6;
913 else
914 {
915 numbuf[--i] = '{';
916 break;
917 }
918 }
919 while (i > 0);
920
921 return png_safecat(buffer, bufsize, pos, numbuf+i);
922 }
923 # define affirm_number(a,b,c,d,e) png_affirm_number(a,b,c,d)
924 #endif /* !HAVE_FORMAT_NUMBER */
925
926 static void
affirm_text(png_charp buffer,size_t bufsize,param_deb (png_const_charp condition)unsigned int position)927 affirm_text(png_charp buffer, size_t bufsize,
928 param_deb(png_const_charp condition) unsigned int position)
929 {
930 /* Format the 'position' number and output:
931 *
932 * "<file> <line>: affirm 'condition' failed\n"
933 * " libpng version <version> - <date>\n"
934 * " translated __DATE__ __TIME__"
935 *
936 * In the STABLE versions the output is the same for the last two lines
937 * but the first line becomes:
938 *
939 * "<position>: affirm failed"
940 *
941 * If there is no number formatting the numbers just get replaced by
942 * some binhex (see the utility above).
943 */
944 size_t pos = 0;
945
946 # if PNG_RELEASE_BUILD /* no 'condition' parameter: minimal text */
947 pos = affirm_number(buffer, bufsize, pos, position, PNG_NUMBER_FORMAT_x);
948 pos = png_safecat(buffer, bufsize, pos, ": affirm failed");
949 # else /* !STABLE */
950 /* Break down 'position' into a file name and a line number: */
951 {
952 # define PNG_apply(f) { #f "\0", PNG_SRC_FILE_ ## f },
953 # define PNG_end { "", PNG_SRC_FILE_LAST }
954 static struct {
955 char filename[28]; /* GCC checks this size */
956 unsigned int base;
957 } fileinfo[] = { PNG_FILES };
958 # undef PNG_apply
959 # undef PNG_end
960
961 unsigned int i;
962 png_const_charp filename;
963
964 /* Do 'nfiles' this way to avoid problems with g++ where it whines
965 * about (size_t) being larger than (int), even though this is a
966 * compile time constant:
967 */
968 # define nfiles ((sizeof fileinfo)/(sizeof (fileinfo[0])))
969 for (i=0; i < nfiles && position > fileinfo[i].base; ++i) {}
970
971 if (i == 0 || i > nfiles)
972 filename = "UNKNOWN";
973 else
974 {
975 filename = fileinfo[i-1].filename;
976 position -= fileinfo[i-1].base;
977 }
978 # undef nfiles
979
980 pos = png_safecat(buffer, bufsize, pos, filename);
981 pos = png_safecat(buffer, bufsize, pos, ".c ");
982 pos = affirm_number(buffer, bufsize, pos, position,
983 PNG_NUMBER_FORMAT_u);
984 }
985
986 pos = png_safecat(buffer, bufsize, pos, ": affirm '");
987 pos = png_safecat(buffer, bufsize, pos, condition);
988 pos = png_safecat(buffer, bufsize, pos, "' failed\n");
989 # endif /* !STABLE */
990
991 pos = png_safecat(buffer, bufsize, pos, PNG_HEADER_VERSION_STRING);
992 pos = png_safecat(buffer, bufsize, pos,
993 " translated " __DATE__ " " __TIME__);
994 }
995
996 #define affirm_text(b, c, p)\
997 do {\
998 (affirm_text)(b, sizeof b, param_deb(c) (p));\
999 } while (0)
1000
1001 #endif /* AFFIRM_TEXT */
1002
1003 PNG_FUNCTION(void,png_affirm,(png_const_structrp png_ptr,
1004 param_deb(png_const_charp condition) unsigned int position),PNG_NORETURN)
1005 {
1006 # if PNG_AFFIRM_TEXT
1007 char buffer[512];
1008
1009 affirm_text(buffer, condition, position);
1010 # else /* !AFFIRM_TEXT */
1011 PNG_UNUSED(position)
1012 # if !PNG_RELEASE_BUILD
1013 PNG_UNUSED(condition)
1014 # endif
1015 # endif /* AFFIRM_TEXT */
1016
1017 /* Now in STABLE do a png_error, but in other builds output the message
1018 * (if possible) then abort (PNG_ABORT).
1019 */
1020 # if PNG_RELEASE_BUILD
1021 png_error(png_ptr, buffer/*macro parameter used only if ERROR_TEXT*/);
1022 # else /* !AFFIRM_ERROR */
1023 /* Use console IO if possible; this is because there is no guarantee that
1024 * the app 'warning' will output anything. For certain the simplified
1025 * API implementation just copies the message (truncated) to the image
1026 * message buffer, which makes debugging much more difficult.
1027 *
1028 * Note that it is possible that neither WARNINGS nor CONSOLE_IO are
1029 * supported; in that case no text will be output (and PNG_AFFIRM_TEXT
1030 * will be false.)
1031 */
1032 # ifdef PNG_CONSOLE_IO_SUPPORTED
1033 fprintf(stderr, "%s\n", buffer);
1034 PNG_UNUSED(png_ptr)
1035 # elif defined PNG_WARNINGS_SUPPORTED
1036 if (png_ptr != NULL && png_ptr->warning_fn != NULL)
1037 png_ptr->warning_fn(png_constcast(png_structrp, png_ptr), buffer);
1038 /* else no way to output the text */
1039 # else
1040 PNG_UNUSED(png_ptr)
1041 # endif
1042
1043 PNG_ABORT
1044 # endif /* AFFIRM_ERROR */
1045 }
1046
1047 #if !PNG_RELEASE_BUILD
1048 void /* PRIVATE */
png_handled_affirm(png_const_structrp png_ptr,png_const_charp message,unsigned int position)1049 png_handled_affirm(png_const_structrp png_ptr, png_const_charp message,
1050 unsigned int position)
1051 {
1052 # if PNG_RELEASE_BUILD
1053 /* testing in RC: we want to return control to the caller, so do not
1054 * use png_affirm.
1055 */
1056 char buffer[512];
1057
1058 affirm_text(buffer, message, position);
1059
1060 # ifdef PNG_CONSOLE_IO_SUPPORTED
1061 fprintf(stderr, "%s\n", buffer);
1062 # elif defined PNG_WARNINGS_SUPPORTED
1063 if (png_ptr != NULL && png_ptr->warning_fn != NULL)
1064 png_ptr->warning_fn(png_constcast(png_structrp, png_ptr), buffer);
1065 /* else no way to output the text */
1066 # else
1067 PNG_UNUSED(png_ptr)
1068 # endif
1069 # else
1070 png_affirm(png_ptr, message, position);
1071 # endif
1072 }
1073 #endif /* !RELEASE_BUILD */
1074
1075 #ifdef PNG_RANGE_CHECK_SUPPORTED
1076 /* The character/byte checking APIs. These do their own calls to png_affirm
1077 * because the caller provides the position.
1078 */
1079 unsigned int /* PRIVATE */
png_bit_affirm(png_const_structrp png_ptr,unsigned int position,unsigned int u,unsigned int bits)1080 png_bit_affirm(png_const_structrp png_ptr, unsigned int position,
1081 unsigned int u, unsigned int bits)
1082 {
1083 /* The following avoids overflow errors even if 'bits' is 16 or 32: */
1084 if (u <= (1U << bits)-1U)
1085 return u;
1086
1087 png_affirm(png_ptr, param_deb("(bit field) range") position);
1088 }
1089
1090 char /* PRIVATE */
png_char_affirm(png_const_structrp png_ptr,unsigned int position,int c)1091 png_char_affirm(png_const_structrp png_ptr, unsigned int position, int c)
1092 {
1093 if (c >= CHAR_MIN && c <= CHAR_MAX)
1094 return (char)/*SAFE*/c;
1095
1096 png_affirm(png_ptr, param_deb("(char) range") position);
1097 }
1098
1099 png_byte /* PRIVATE */
png_byte_affirm(png_const_structrp png_ptr,unsigned int position,int b)1100 png_byte_affirm(png_const_structrp png_ptr, unsigned int position, int b)
1101 {
1102 /* For the type png_byte the limits.h values are ignored and we check
1103 * against the values PNG expects to store in a byte:
1104 */
1105 if (b >= 0 && b <= 255)
1106 return (png_byte)/*SAFE*/b;
1107
1108 png_affirm(png_ptr, param_deb("PNG byte range") position);
1109 }
1110
1111 #if INT_MAX >= 65535
1112 png_uint_16 /* PRIVATE */
png_u16_affirm(png_const_structrp png_ptr,unsigned int position,int b)1113 png_u16_affirm(png_const_structrp png_ptr, unsigned int position, int b)
1114 {
1115 /* Check against the PNG 16-bit limit, as with png_byte. */
1116 if (b >= 0 && b <= 65535)
1117 return (png_uint_16)/*SAFE*/b;
1118
1119 png_affirm(png_ptr, param_deb("PNG 16-bit range") position);
1120 }
1121 #endif /* INT_MAX >= 65535 */
1122 #endif /* RANGE_CHECK */
1123 #endif /* READ || WRITE */
1124