1
2/* pngerror.c - stub functions for i/o and memory allocation
3 *
4 * Copyright (c) 2018 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * 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
21#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
22
23static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
24 png_const_charp error_message)),PNG_NORETURN);
25
26#ifdef PNG_WARNINGS_SUPPORTED
27static void /* PRIVATE */
28png_default_warning PNGARG((png_const_structrp png_ptr,
29 png_const_charp warning_message));
30#endif /* WARNINGS */
31
32/* This function is called whenever there is a fatal error. This function
33 * should not be changed. If there is a need to handle errors differently,
34 * you should supply a replacement error function and use png_set_error_fn()
35 * to replace the error function at run-time.
36 */
37#ifdef PNG_ERROR_TEXT_SUPPORTED
38PNG_FUNCTION(void,PNGAPI
39png_error,(png_const_structrp png_ptr, png_const_charp error_message),
40 PNG_NORETURN)
41{
42#ifdef PNG_ERROR_NUMBERS_SUPPORTED
43 char msg[16];
44 if (png_ptr != NULL)
45 {
46 if ((png_ptr->flags &
47 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
48 {
49 if (*error_message == PNG_LITERAL_SHARP)
50 {
51 /* Strip "#nnnn " from beginning of error message. */
52 int offset;
53 for (offset = 1; offset<15; offset++)
54 if (error_message[offset] == ' ')
55 break;
56
57 if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
58 {
59 int i;
60 for (i = 0; i < offset - 1; i++)
61 msg[i] = error_message[i + 1];
62 msg[i - 1] = '\0';
63 error_message = msg;
64 }
65
66 else
67 error_message += offset;
68 }
69
70 else
71 {
72 if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
73 {
74 msg[0] = '0';
75 msg[1] = '\0';
76 error_message = msg;
77 }
78 }
79 }
80 }
81#endif
82 if (png_ptr != NULL && png_ptr->error_fn != NULL)
83 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),
84 error_message);
85
86 /* If the custom handler doesn't exist, or if it returns,
87 use the default handler, which will not return. */
88 png_default_error(png_ptr, error_message);
89}
90#else
91PNG_FUNCTION(void,PNGAPI
92png_err,(png_const_structrp png_ptr),PNG_NORETURN)
93{
94 /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
95 * erroneously as '\0', instead of the empty string "". This was
96 * apparently an error, introduced in libpng-1.2.20, and png_default_error
97 * will crash in this case.
98 */
99 if (png_ptr != NULL && png_ptr->error_fn != NULL)
100 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");
101
102 /* If the custom handler doesn't exist, or if it returns,
103 use the default handler, which will not return. */
104 png_default_error(png_ptr, "");
105}
106#endif /* ERROR_TEXT */
107
108/* Utility to safely appends strings to a buffer. This never errors out so
109 * error checking is not required in the caller.
110 */
111size_t
112png_safecat(png_charp buffer, size_t bufsize, size_t pos,
113 png_const_charp string)
114{
115 if (buffer != NULL && pos < bufsize)
116 {
117 if (string != NULL)
118 while (*string != '\0' && pos < bufsize-1)
119 buffer[pos++] = *string++;
120
121 buffer[pos] = '\0';
122 }
123
124 return pos;
125}
126
127#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
128/* Utility to dump an unsigned value into a buffer, given a start pointer and
129 * and end pointer (which should point just *beyond* the end of the buffer!)
130 * Returns the pointer to the start of the formatted string.
131 */
132png_charp
133png_format_number(png_const_charp start, png_charp end, int format,
134 png_alloc_size_t number)
135{
136 int count = 0; /* number of digits output */
137 int mincount = 1; /* minimum number required */
138 int output = 0; /* digit output (for the fixed point format) */
139
140 *--end = '\0';
141
142 /* This is written so that the loop always runs at least once, even with
143 * number zero.
144 */
145 while (end > start && (number != 0 || count < mincount))
146 {
147
148 static const char digits[] = "0123456789ABCDEF";
149
150 switch (format)
151 {
152 case PNG_NUMBER_FORMAT_fixed:
153 /* Needs five digits (the fraction) */
154 mincount = 5;
155 if (output != 0 || number % 10 != 0)
156 {
157 *--end = digits[number % 10];
158 output = 1;
159 }
160 number /= 10;
161 break;
162
163 case PNG_NUMBER_FORMAT_02u:
164 /* Expects at least 2 digits. */
165 mincount = 2;
166 /* FALLTHROUGH */
167
168 case PNG_NUMBER_FORMAT_u:
169 *--end = digits[number % 10];
170 number /= 10;
171 break;
172
173 case PNG_NUMBER_FORMAT_02x:
174 /* This format expects at least two digits */
175 mincount = 2;
176 /* FALLTHROUGH */
177
178 case PNG_NUMBER_FORMAT_x:
179 *--end = digits[number & 0xf];
180 number >>= 4;
181 break;
182
183 default: /* an error */
184 number = 0;
185 break;
186 }
187
188 /* Keep track of the number of digits added */
189 ++count;
190
191 /* Float a fixed number here: */
192 if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
193 {
194 /* End of the fraction, but maybe nothing was output? In that case
195 * drop the decimal point. If the number is a true zero handle that
196 * here.
197 */
198 if (output != 0)
199 *--end = '.';
200 else if (number == 0) /* and !output */
201 *--end = '0';
202 }
203 }
204
205 return end;
206}
207#endif
208
209#ifdef PNG_WARNINGS_SUPPORTED
210/* This function is called whenever there is a non-fatal error. This function
211 * should not be changed. If there is a need to handle warnings differently,
212 * you should supply a replacement warning function and use
213 * png_set_error_fn() to replace the warning function at run-time.
214 */
215void PNGAPI
216png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
217{
218 int offset = 0;
219 if (png_ptr != NULL)
220 {
221#ifdef PNG_ERROR_NUMBERS_SUPPORTED
222 if ((png_ptr->flags &
223 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
224#endif
225 {
226 if (*warning_message == PNG_LITERAL_SHARP)
227 {
228 for (offset = 1; offset < 15; offset++)
229 if (warning_message[offset] == ' ')
230 break;
231 }
232 }
233 }
234 if (png_ptr != NULL && png_ptr->warning_fn != NULL)
235 (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
236 warning_message + offset);
237 else
238 png_default_warning(png_ptr, warning_message + offset);
239}
240
241/* These functions support 'formatted' warning messages with up to
242 * PNG_WARNING_PARAMETER_COUNT parameters. In the format string the parameter
243 * is introduced by @<number>, where 'number' starts at 1. This follows the
244 * standard established by X/Open for internationalizable error messages.
245 */
246void
247png_warning_parameter(png_warning_parameters p, int number,
248 png_const_charp string)
249{
250 if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
251 (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
252}
253
254void
255png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
256 png_alloc_size_t value)
257{
258 char buffer[PNG_NUMBER_BUFFER_SIZE];
259 png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
260}
261
262void
263png_warning_parameter_signed(png_warning_parameters p, int number, int format,
264 png_int_32 value)
265{
266 png_alloc_size_t u;
267 png_charp str;
268 char buffer[PNG_NUMBER_BUFFER_SIZE];
269
270 /* Avoid overflow by doing the negate in a png_alloc_size_t: */
271 u = (png_alloc_size_t)value;
272 if (value < 0)
273 u = ~u + 1;
274
275 str = PNG_FORMAT_NUMBER(buffer, format, u);
276
277 if (value < 0 && str > buffer)
278 *--str = '-';
279
280 png_warning_parameter(p, number, str);
281}
282
283void
284png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
285 png_const_charp message)
286{
287 /* The internal buffer is just 192 bytes - enough for all our messages,
288 * overflow doesn't happen because this code checks! If someone figures
289 * out how to send us a message longer than 192 bytes, all that will
290 * happen is that the message will be truncated appropriately.
291 */
292 size_t i = 0; /* Index in the msg[] buffer: */
293 char msg[192];
294
295 /* Each iteration through the following loop writes at most one character
296 * to msg[i++] then returns here to validate that there is still space for
297 * the trailing '\0'. It may (in the case of a parameter) read more than
298 * one character from message[]; it must check for '\0' and continue to the
299 * test if it finds the end of string.
300 */
301 while (i<(sizeof msg)-1 && *message != '\0')
302 {
303 /* '@' at end of string is now just printed (previously it was skipped);
304 * it is an error in the calling code to terminate the string with @.
305 */
306 if (p != NULL && *message == '@' && message[1] != '\0')
307 {
308 int parameter_char = *++message; /* Consume the '@' */
309 static const char valid_parameters[] = "123456789";
310 int parameter = 0;
311
312 /* Search for the parameter digit, the index in the string is the
313 * parameter to use.
314 */
315 while (valid_parameters[parameter] != parameter_char &&
316 valid_parameters[parameter] != '\0')
317 ++parameter;
318
319 /* If the parameter digit is out of range it will just get printed. */
320 if (parameter < PNG_WARNING_PARAMETER_COUNT)
321 {
322 /* Append this parameter */
323 png_const_charp parm = p[parameter];
324 png_const_charp pend = p[parameter] + (sizeof p[parameter]);
325
326 /* No need to copy the trailing '\0' here, but there is no guarantee
327 * that parm[] has been initialized, so there is no guarantee of a
328 * trailing '\0':
329 */
330 while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
331 msg[i++] = *parm++;
332
333 /* Consume the parameter digit too: */
334 ++message;
335 continue;
336 }
337
338 /* else not a parameter and there is a character after the @ sign; just
339 * copy that. This is known not to be '\0' because of the test above.
340 */
341 }
342
343 /* At this point *message can't be '\0', even in the bad parameter case
344 * above where there is a lone '@' at the end of the message string.
345 */
346 msg[i++] = *message++;
347 }
348
349 /* i is always less than (sizeof msg), so: */
350 msg[i] = '\0';
351
352 /* And this is the formatted message. It may be larger than
353 * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
354 * are not (currently) formatted.
355 */
356 png_warning(png_ptr, msg);
357}
358#endif /* WARNINGS */
359
360#ifdef PNG_BENIGN_ERRORS_SUPPORTED
361void PNGAPI
362png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
363{
364 if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
365 {
366# ifdef PNG_READ_SUPPORTED
367 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
368 png_ptr->chunk_name != 0)
369 png_chunk_warning(png_ptr, error_message);
370 else
371# endif
372 png_warning(png_ptr, error_message);
373 }
374
375 else
376 {
377# ifdef PNG_READ_SUPPORTED
378 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
379 png_ptr->chunk_name != 0)
380 png_chunk_error(png_ptr, error_message);
381 else
382# endif
383 png_error(png_ptr, error_message);
384 }
385
386# ifndef PNG_ERROR_TEXT_SUPPORTED
387 PNG_UNUSED(error_message)
388# endif
389}
390
391void /* PRIVATE */
392png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
393{
394 if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
395 png_warning(png_ptr, error_message);
396 else
397 png_error(png_ptr, error_message);
398
399# ifndef PNG_ERROR_TEXT_SUPPORTED
400 PNG_UNUSED(error_message)
401# endif
402}
403
404void /* PRIVATE */
405png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
406{
407 if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
408 png_warning(png_ptr, error_message);
409 else
410 png_error(png_ptr, error_message);
411
412# ifndef PNG_ERROR_TEXT_SUPPORTED
413 PNG_UNUSED(error_message)
414# endif
415}
416#endif /* BENIGN_ERRORS */
417
418#define PNG_MAX_ERROR_TEXT 196 /* Currently limited by profile_error in png.c */
419#if defined(PNG_WARNINGS_SUPPORTED) || \
420 (defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))
421/* These utilities are used internally to build an error message that relates
422 * to the current chunk. The chunk name comes from png_ptr->chunk_name,
423 * which is used to prefix the message. The message is limited in length
424 * to 63 bytes. The name characters are output as hex digits wrapped in []
425 * if the character is invalid.
426 */
427#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
428static const char png_digit[16] = {
429 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
430 'A', 'B', 'C', 'D', 'E', 'F'
431};
432
433static void /* PRIVATE */
434png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
435 error_message)
436{
437 png_uint_32 chunk_name = png_ptr->chunk_name;
438 int iout = 0, ishift = 24;
439
440 while (ishift >= 0)
441 {
442 int c = (int)(chunk_name >> ishift) & 0xff;
443
444 ishift -= 8;
445 if (isnonalpha(c) != 0)
446 {
447 buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
448 buffer[iout++] = png_digit[(c & 0xf0) >> 4];
449 buffer[iout++] = png_digit[c & 0x0f];
450 buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
451 }
452
453 else
454 {
455 buffer[iout++] = (char)c;
456 }
457 }
458
459 if (error_message == NULL)
460 buffer[iout] = '\0';
461
462 else
463 {
464 int iin = 0;
465
466 buffer[iout++] = ':';
467 buffer[iout++] = ' ';
468
469 while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
470 buffer[iout++] = error_message[iin++];
471
472 /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
473 buffer[iout] = '\0';
474 }
475}
476#endif /* WARNINGS || ERROR_TEXT */
477
478#if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
479PNG_FUNCTION(void,PNGAPI
480png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
481 PNG_NORETURN)
482{
483 char msg[18+PNG_MAX_ERROR_TEXT];
484 if (png_ptr == NULL)
485 png_error(png_ptr, error_message);
486
487 else
488 {
489 png_format_buffer(png_ptr, msg, error_message);
490 png_error(png_ptr, msg);
491 }
492}
493#endif /* READ && ERROR_TEXT */
494
495#ifdef PNG_WARNINGS_SUPPORTED
496void PNGAPI
497png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
498{
499 char msg[18+PNG_MAX_ERROR_TEXT];
500 if (png_ptr == NULL)
501 png_warning(png_ptr, warning_message);
502
503 else
504 {
505 png_format_buffer(png_ptr, msg, warning_message);
506 png_warning(png_ptr, msg);
507 }
508}
509#endif /* WARNINGS */
510
511#ifdef PNG_READ_SUPPORTED
512#ifdef PNG_BENIGN_ERRORS_SUPPORTED
513void PNGAPI
514png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
515 error_message)
516{
517 if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
518 png_chunk_warning(png_ptr, error_message);
519
520 else
521 png_chunk_error(png_ptr, error_message);
522
523# ifndef PNG_ERROR_TEXT_SUPPORTED
524 PNG_UNUSED(error_message)
525# endif
526}
527#endif
528#endif /* READ */
529
530void /* PRIVATE */
531png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
532{
533# ifndef PNG_WARNINGS_SUPPORTED
534 PNG_UNUSED(message)
535# endif
536
537 /* This is always supported, but for just read or just write it
538 * unconditionally does the right thing.
539 */
540# if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
541 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
542# endif
543
544# ifdef PNG_READ_SUPPORTED
545 {
546 if (error < PNG_CHUNK_ERROR)
547 png_chunk_warning(png_ptr, message);
548
549 else
550 png_chunk_benign_error(png_ptr, message);
551 }
552# endif
553
554# if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
555 else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
556# endif
557
558# ifdef PNG_WRITE_SUPPORTED
559 {
560 if (error < PNG_CHUNK_WRITE_ERROR)
561 png_app_warning(png_ptr, message);
562
563 else
564 png_app_error(png_ptr, message);
565 }
566# endif
567}
568
569#ifdef PNG_ERROR_TEXT_SUPPORTED
570#ifdef PNG_FLOATING_POINT_SUPPORTED
571PNG_FUNCTION(void,
572png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
573{
574# define fixed_message "fixed point overflow in "
575# define fixed_message_ln ((sizeof fixed_message)-1)
576 unsigned int iin;
577 char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
578 memcpy(msg, fixed_message, fixed_message_ln);
579 iin = 0;
580 if (name != NULL)
581 while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
582 {
583 msg[fixed_message_ln + iin] = name[iin];
584 ++iin;
585 }
586 msg[fixed_message_ln + iin] = 0;
587 png_error(png_ptr, msg);
588}
589#endif
590#endif
591
592#ifdef PNG_SETJMP_SUPPORTED
593/* This API only exists if ANSI-C style error handling is used,
594 * otherwise it is necessary for png_default_error to be overridden.
595 */
596jmp_buf* PNGAPI
597png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
598 size_t jmp_buf_size)
599{
600 /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
601 * and it must not change after that. Libpng doesn't care how big the
602 * buffer is, just that it doesn't change.
603 *
604 * If the buffer size is no *larger* than the size of jmp_buf when libpng is
605 * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
606 * semantics that this call will not fail. If the size is larger, however,
607 * the buffer is allocated and this may fail, causing the function to return
608 * NULL.
609 */
610 if (png_ptr == NULL)
611 return NULL;
612
613 if (png_ptr->jmp_buf_ptr == NULL)
614 {
615 png_ptr->jmp_buf_size = 0; /* not allocated */
616
617 if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
618 png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
619
620 else
621 {
622 png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
623 png_malloc_warn(png_ptr, jmp_buf_size));
624
625 if (png_ptr->jmp_buf_ptr == NULL)
626 return NULL; /* new NULL return on OOM */
627
628 png_ptr->jmp_buf_size = jmp_buf_size;
629 }
630 }
631
632 else /* Already allocated: check the size */
633 {
634 size_t size = png_ptr->jmp_buf_size;
635
636 if (size == 0)
637 {
638 size = (sizeof png_ptr->jmp_buf_local);
639 if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
640 {
641 /* This is an internal error in libpng: somehow we have been left
642 * with a stack allocated jmp_buf when the application regained
643 * control. It's always possible to fix this up, but for the moment
644 * this is a png_error because that makes it easy to detect.
645 */
646 png_error(png_ptr, "Libpng jmp_buf still allocated");
647 /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
648 }
649 }
650
651 if (size != jmp_buf_size)
652 {
653 png_warning(png_ptr, "Application jmp_buf size changed");
654 return NULL; /* caller will probably crash: no choice here */
655 }
656 }
657
658 /* Finally fill in the function, now we have a satisfactory buffer. It is
659 * valid to change the function on every call.
660 */
661 png_ptr->longjmp_fn = longjmp_fn;
662 return png_ptr->jmp_buf_ptr;
663}
664
665void /* PRIVATE */
666png_free_jmpbuf(png_structrp png_ptr)
667{
668 if (png_ptr != NULL)
669 {
670 jmp_buf *jb = png_ptr->jmp_buf_ptr;
671
672 /* A size of 0 is used to indicate a local, stack, allocation of the
673 * pointer; used here and in png.c
674 */
675 if (jb != NULL && png_ptr->jmp_buf_size > 0)
676 {
677
678 /* This stuff is so that a failure to free the error control structure
679 * does not leave libpng in a state with no valid error handling: the
680 * free always succeeds, if there is an error it gets ignored.
681 */
682 if (jb != &png_ptr->jmp_buf_local)
683 {
684 /* Make an internal, libpng, jmp_buf to return here */
685 jmp_buf free_jmp_buf;
686
687 if (!setjmp(free_jmp_buf))
688 {
689 png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
690 png_ptr->jmp_buf_size = 0; /* stack allocation */
691 png_ptr->longjmp_fn = longjmp;
692 png_free(png_ptr, jb); /* Return to setjmp on error */
693 }
694 }
695 }
696
697 /* *Always* cancel everything out: */
698 png_ptr->jmp_buf_size = 0;
699 png_ptr->jmp_buf_ptr = NULL;
700 png_ptr->longjmp_fn = 0;
701 }
702}
703#endif
704
705/* This is the default error handling function. Note that replacements for
706 * this function MUST NOT RETURN, or the program will likely crash. This
707 * function is used by default, or if the program supplies NULL for the
708 * error function pointer in png_set_error_fn().
709 */
710static PNG_FUNCTION(void /* PRIVATE */,
711png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
712 PNG_NORETURN)
713{
714#ifdef PNG_CONSOLE_IO_SUPPORTED
715#ifdef PNG_ERROR_NUMBERS_SUPPORTED
716 /* Check on NULL only added in 1.5.4 */
717 if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
718 {
719 /* Strip "#nnnn " from beginning of error message. */
720 int offset;
721 char error_number[16];
722 for (offset = 0; offset<15; offset++)
723 {
724 error_number[offset] = error_message[offset + 1];
725 if (error_message[offset] == ' ')
726 break;
727 }
728
729 if ((offset > 1) && (offset < 15))
730 {
731 error_number[offset - 1] = '\0';
732 fprintf(stderr, "libpng error no. %s: %s",
733 error_number, error_message + offset + 1);
734 fprintf(stderr, PNG_STRING_NEWLINE);
735 }
736
737 else
738 {
739 fprintf(stderr, "libpng error: %s, offset=%d",
740 error_message, offset);
741 fprintf(stderr, PNG_STRING_NEWLINE);
742 }
743 }
744 else
745#endif
746 {
747 fprintf(stderr, "libpng error: %s", error_message ? error_message :
748 "undefined");
749 fprintf(stderr, PNG_STRING_NEWLINE);
750 }
751#else
752 PNG_UNUSED(error_message) /* Make compiler happy */
753#endif
754 png_longjmp(png_ptr, 1);
755}
756
757PNG_FUNCTION(void,PNGAPI
758png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
759{
760#ifdef PNG_SETJMP_SUPPORTED
761 if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
762 png_ptr->jmp_buf_ptr != NULL)
763 png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
764#else
765 PNG_UNUSED(png_ptr)
766 PNG_UNUSED(val)
767#endif
768
769 /* If control reaches this point, png_longjmp() must not return. The only
770 * choice is to terminate the whole process (or maybe the thread); to do
771 * this the ANSI-C abort() function is used unless a different method is
772 * implemented by overriding the default configuration setting for
773 * PNG_ABORT().
774 */
775 PNG_ABORT();
776}
777
778#ifdef PNG_WARNINGS_SUPPORTED
779/* This function is called when there is a warning, but the library thinks
780 * it can continue anyway. Replacement functions don't have to do anything
781 * here if you don't want them to. In the default configuration, png_ptr is
782 * not used, but it is passed in case it may be useful.
783 */
784static void /* PRIVATE */
785png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
786{
787#ifdef PNG_CONSOLE_IO_SUPPORTED
788# ifdef PNG_ERROR_NUMBERS_SUPPORTED
789 if (*warning_message == PNG_LITERAL_SHARP)
790 {
791 int offset;
792 char warning_number[16];
793 for (offset = 0; offset < 15; offset++)
794 {
795 warning_number[offset] = warning_message[offset + 1];
796 if (warning_message[offset] == ' ')
797 break;
798 }
799
800 if ((offset > 1) && (offset < 15))
801 {
802 warning_number[offset + 1] = '\0';
803 fprintf(stderr, "libpng warning no. %s: %s",
804 warning_number, warning_message + offset);
805 fprintf(stderr, PNG_STRING_NEWLINE);
806 }
807
808 else
809 {
810 fprintf(stderr, "libpng warning: %s",
811 warning_message);
812 fprintf(stderr, PNG_STRING_NEWLINE);
813 }
814 }
815 else
816# endif
817
818 {
819 fprintf(stderr, "libpng warning: %s", warning_message);
820 fprintf(stderr, PNG_STRING_NEWLINE);
821 }
822#else
823 PNG_UNUSED(warning_message) /* Make compiler happy */
824#endif
825 PNG_UNUSED(png_ptr) /* Make compiler happy */
826}
827#endif /* WARNINGS */
828
829/* This function is called when the application wants to use another method
830 * of handling errors and warnings. Note that the error function MUST NOT
831 * return to the calling routine or serious problems will occur. The return
832 * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
833 */
834void PNGAPI
835png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
836 png_error_ptr error_fn, png_error_ptr warning_fn)
837{
838 if (png_ptr == NULL)
839 return;
840
841 png_ptr->error_ptr = error_ptr;
842 png_ptr->error_fn = error_fn;
843#ifdef PNG_WARNINGS_SUPPORTED
844 png_ptr->warning_fn = warning_fn;
845#else
846 PNG_UNUSED(warning_fn)
847#endif
848}
849
850
851/* This function returns a pointer to the error_ptr associated with the user
852 * functions. The application should free any memory associated with this
853 * pointer before png_write_destroy and png_read_destroy are called.
854 */
855png_voidp PNGAPI
856png_get_error_ptr(png_const_structrp png_ptr)
857{
858 if (png_ptr == NULL)
859 return NULL;
860
861 return ((png_voidp)png_ptr->error_ptr);
862}
863
864
865#ifdef PNG_ERROR_NUMBERS_SUPPORTED
866void PNGAPI
867png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
868{
869 if (png_ptr != NULL)
870 {
871 png_ptr->flags &=
872 ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
873 PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
874 }
875}
876#endif
877
878#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
879 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
880 /* Currently the above both depend on SETJMP_SUPPORTED, however it would be
881 * possible to implement without setjmp support just so long as there is some
882 * way to handle the error return here:
883 */
884PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
885png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
886 PNG_NORETURN)
887{
888 png_const_structrp png_ptr = png_nonconst_ptr;
889 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
890
891 /* An error is always logged here, overwriting anything (typically a warning)
892 * that is already there:
893 */
894 if (image != NULL)
895 {
896 png_safecat(image->message, (sizeof image->message), 0, error_message);
897 image->warning_or_error |= PNG_IMAGE_ERROR;
898
899 /* Retrieve the jmp_buf from within the png_control, making this work for
900 * C++ compilation too is pretty tricky: C++ wants a pointer to the first
901 * element of a jmp_buf, but C doesn't tell us the type of that.
902 */
903 if (image->opaque != NULL && image->opaque->error_buf != NULL)
904 longjmp(png_control_jmp_buf(image->opaque), 1);
905
906 /* Missing longjmp buffer, the following is to help debugging: */
907 {
908 size_t pos = png_safecat(image->message, (sizeof image->message), 0,
909 "bad longjmp: ");
910 png_safecat(image->message, (sizeof image->message), pos,
911 error_message);
912 }
913 }
914
915 /* Here on an internal programming error. */
916 abort();
917}
918
919#ifdef PNG_WARNINGS_SUPPORTED
920void /* PRIVATE */ PNGCBAPI
921png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
922{
923 png_const_structrp png_ptr = png_nonconst_ptr;
924 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
925
926 /* A warning is only logged if there is no prior warning or error. */
927 if (image->warning_or_error == 0)
928 {
929 png_safecat(image->message, (sizeof image->message), 0, warning_message);
930 image->warning_or_error |= PNG_IMAGE_WARNING;
931 }
932}
933#endif
934
935int /* PRIVATE */
936png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
937{
938 volatile png_imagep image = image_in;
939 volatile int result;
940 volatile png_voidp saved_error_buf;
941 jmp_buf safe_jmpbuf;
942
943 /* Safely execute function(arg) with png_error returning to this function. */
944 saved_error_buf = image->opaque->error_buf;
945 result = setjmp(safe_jmpbuf) == 0;
946
947 if (result != 0)
948 {
949
950 image->opaque->error_buf = safe_jmpbuf;
951 result = function(arg);
952 }
953
954 image->opaque->error_buf = saved_error_buf;
955
956 /* And do the cleanup prior to any failure return. */
957 if (result == 0)
958 png_image_free(image);
959
960 return result;
961}
962#endif /* SIMPLIFIED READ || SIMPLIFIED_WRITE */
963#endif /* READ || WRITE */
964