1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngerror.c - stub functions for i/o and memory allocation
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.15 [November 20, 2014]
33 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 *
41 * This file provides a location for all error handling. Users who
42 * need special error handling are expected to write replacement functions
43 * and use png_set_error_fn() to use those functions. See the instructions
44 * at each function.
45 */
46
47 #include "pngpriv.h"
48
49 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
50
51 static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
52 png_const_charp error_message)),PNG_NORETURN);
53
54 #ifdef PNG_WARNINGS_SUPPORTED
55 static void /* PRIVATE */
56 png_default_warning PNGARG((png_const_structrp png_ptr,
57 png_const_charp warning_message));
58 #endif /* WARNINGS */
59
60 /* This function is called whenever there is a fatal error. This function
61 * should not be changed. If there is a need to handle errors differently,
62 * you should supply a replacement error function and use png_set_error_fn()
63 * to replace the error function at run-time.
64 */
65 #ifdef PNG_ERROR_TEXT_SUPPORTED
66 PNG_FUNCTION(void,PNGAPI
67 png_error,(png_const_structrp png_ptr, png_const_charp error_message),
68 PNG_NORETURN)
69 {
70 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
71 char msg[16];
72 if (png_ptr != NULL)
73 {
74 if ((png_ptr->flags &
75 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0
76 {
77 if (*error_message == PNG_LITERAL_SHARP)
78 {
79 /* Strip "#nnnn " from beginning of error message. */
80 int offset;
81 for (offset = 1; offset<15; offset++)
82 if (error_message[offset] == ' ')
83 break;
84
85 if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
86 {
87 int i;
88 for (i = 0; i < offset - 1; i++)
89 msg[i] = error_message[i + 1];
90 msg[i - 1] = '\0';
91 error_message = msg;
92 }
93
94 else
95 error_message += offset;
96 }
97
98 else
99 {
100 if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
101 {
102 msg[0] = '0';
103 msg[1] = '\0';
104 error_message = msg;
105 }
106 }
107 }
108 }
109 #endif
110 if (png_ptr != NULL && png_ptr->error_fn != NULL)
111 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),
112 error_message);
113
114 /* If the custom handler doesn't exist, or if it returns,
115 use the default handler, which will not return. */
116 png_default_error(png_ptr, error_message);
117 }
118 #else
119 PNG_FUNCTION(void,PNGAPI
120 png_err,(png_const_structrp png_ptr),PNG_NORETURN)
121 {
122 /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
123 * erroneously as '\0', instead of the empty string "". This was
124 * apparently an error, introduced in libpng-1.2.20, and png_default_error
125 * will crash in this case.
126 */
127 if (png_ptr != NULL && png_ptr->error_fn != NULL)
128 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");
129
130 /* If the custom handler doesn't exist, or if it returns,
131 use the default handler, which will not return. */
132 png_default_error(png_ptr, "");
133 }
134 #endif /* ERROR_TEXT */
135
136 /* Utility to safely appends strings to a buffer. This never errors out so
137 * error checking is not required in the caller.
138 */
139 size_t
140 png_safecat(png_charp buffer, size_t bufsize, size_t pos,
141 png_const_charp string)
142 {
143 if (buffer != NULL && pos < bufsize)
144 {
145 if (string != NULL)
146 while (*string != '\0' && pos < bufsize-1)
147 buffer[pos++] = *string++;
148
149 buffer[pos] = '\0';
150 }
151
152 return pos;
153 }
154
155 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
156 /* Utility to dump an unsigned value into a buffer, given a start pointer and
157 * and end pointer (which should point just *beyond* the end of the buffer!)
158 * Returns the pointer to the start of the formatted string.
159 */
160 png_charp
161 png_format_number(png_const_charp start, png_charp end, int format,
162 png_alloc_size_t number)
163 {
164 int count = 0; /* number of digits output */
165 int mincount = 1; /* minimum number required */
166 int output = 0; /* digit output (for the fixed point format) */
167
168 *--end = '\0';
169
170 /* This is written so that the loop always runs at least once, even with
171 * number zero.
172 */
173 while (end > start && (number != 0 || count < mincount))
174 {
175
176 static const char digits[] = "0123456789ABCDEF";
177
178 switch (format)
179 {
180 case PNG_NUMBER_FORMAT_fixed:
181 /* Needs five digits (the fraction) */
182 mincount = 5;
183 if (output != 0 || number % 10 != 0)
184 {
185 *--end = digits[number % 10];
186 output = 1;
187 }
188 number /= 10;
189 break;
190
191 case PNG_NUMBER_FORMAT_02u:
192 /* Expects at least 2 digits. */
193 mincount = 2;
194 /* FALL THROUGH */
195
196 case PNG_NUMBER_FORMAT_u:
197 *--end = digits[number % 10];
198 number /= 10;
199 break;
200
201 case PNG_NUMBER_FORMAT_02x:
202 /* This format expects at least two digits */
203 mincount = 2;
204 /* FALL THROUGH */
205
206 case PNG_NUMBER_FORMAT_x:
207 *--end = digits[number & 0xf];
208 number >>= 4;
209 break;
210
211 default: /* an error */
212 number = 0;
213 break;
214 }
215
216 /* Keep track of the number of digits added */
217 ++count;
218
219 /* Float a fixed number here: */
220 if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
221 {
222 /* End of the fraction, but maybe nothing was output? In that case
223 * drop the decimal point. If the number is a true zero handle that
224 * here.
225 */
226 if (output != 0)
227 *--end = '.';
228 else if (number == 0) /* and !output */
229 *--end = '0';
230 }
231 }
232
233 return end;
234 }
235 #endif
236
237 #ifdef PNG_WARNINGS_SUPPORTED
238 /* This function is called whenever there is a non-fatal error. This function
239 * should not be changed. If there is a need to handle warnings differently,
240 * you should supply a replacement warning function and use
241 * png_set_error_fn() to replace the warning function at run-time.
242 */
243 void PNGAPI
244 png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
245 {
246 int offset = 0;
247 if (png_ptr != NULL)
248 {
249 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
250 if ((png_ptr->flags &
251 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
252 #endif
253 {
254 if (*warning_message == PNG_LITERAL_SHARP)
255 {
256 for (offset = 1; offset < 15; offset++)
257 if (warning_message[offset] == ' ')
258 break;
259 }
260 }
261 }
262 if (png_ptr != NULL && png_ptr->warning_fn != NULL)
263 (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
264 warning_message + offset);
265 else
266 png_default_warning(png_ptr, warning_message + offset);
267 }
268
269 /* These functions support 'formatted' warning messages with up to
270 * PNG_WARNING_PARAMETER_COUNT parameters. In the format string the parameter
271 * is introduced by @<number>, where 'number' starts at 1. This follows the
272 * standard established by X/Open for internationalizable error messages.
273 */
274 void
275 png_warning_parameter(png_warning_parameters p, int number,
276 png_const_charp string)
277 {
278 if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
279 (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
280 }
281
282 void
283 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
284 png_alloc_size_t value)
285 {
286 char buffer[PNG_NUMBER_BUFFER_SIZE];
287 png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
288 }
289
290 void
291 png_warning_parameter_signed(png_warning_parameters p, int number, int format,
292 png_int_32 value)
293 {
294 png_alloc_size_t u;
295 png_charp str;
296 char buffer[PNG_NUMBER_BUFFER_SIZE];
297
298 /* Avoid overflow by doing the negate in a png_alloc_size_t: */
299 u = (png_alloc_size_t)value;
300 if (value < 0)
301 u = ~u + 1;
302
303 str = PNG_FORMAT_NUMBER(buffer, format, u);
304
305 if (value < 0 && str > buffer)
306 *--str = '-';
307
308 png_warning_parameter(p, number, str);
309 }
310
311 void
312 png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
313 png_const_charp message)
314 {
315 /* The internal buffer is just 192 bytes - enough for all our messages,
316 * overflow doesn't happen because this code checks! If someone figures
317 * out how to send us a message longer than 192 bytes, all that will
318 * happen is that the message will be truncated appropriately.
319 */
320 size_t i = 0; /* Index in the msg[] buffer: */
321 char msg[192];
322
323 /* Each iteration through the following loop writes at most one character
324 * to msg[i++] then returns here to validate that there is still space for
325 * the trailing '\0'. It may (in the case of a parameter) read more than
326 * one character from message[]; it must check for '\0' and continue to the
327 * test if it finds the end of string.
328 */
329 while (i<(sizeof msg)-1 && *message != '\0')
330 {
331 /* '@' at end of string is now just printed (previously it was skipped);
332 * it is an error in the calling code to terminate the string with @.
333 */
334 if (p != NULL && *message == '@' && message[1] != '\0')
335 {
336 int parameter_char = *++message; /* Consume the '@' */
337 static const char valid_parameters[] = "123456789";
338 int parameter = 0;
339
340 /* Search for the parameter digit, the index in the string is the
341 * parameter to use.
342 */
343 while (valid_parameters[parameter] != parameter_char &&
344 valid_parameters[parameter] != '\0')
345 ++parameter;
346
347 /* If the parameter digit is out of range it will just get printed. */
348 if (parameter < PNG_WARNING_PARAMETER_COUNT)
349 {
350 /* Append this parameter */
351 png_const_charp parm = p[parameter];
352 png_const_charp pend = p[parameter] + (sizeof p[parameter]);
353
354 /* No need to copy the trailing '\0' here, but there is no guarantee
355 * that parm[] has been initialized, so there is no guarantee of a
356 * trailing '\0':
357 */
358 while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
359 msg[i++] = *parm++;
360
361 /* Consume the parameter digit too: */
362 ++message;
363 continue;
364 }
365
366 /* else not a parameter and there is a character after the @ sign; just
367 * copy that. This is known not to be '\0' because of the test above.
368 */
369 }
370
371 /* At this point *message can't be '\0', even in the bad parameter case
372 * above where there is a lone '@' at the end of the message string.
373 */
374 msg[i++] = *message++;
375 }
376
377 /* i is always less than (sizeof msg), so: */
378 msg[i] = '\0';
379
380 /* And this is the formatted message. It may be larger than
381 * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
382 * are not (currently) formatted.
383 */
384 png_warning(png_ptr, msg);
385 }
386 #endif /* WARNINGS */
387
388 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
389 void PNGAPI
390 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
391 {
392 if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
393 {
394 # ifdef PNG_READ_SUPPORTED
395 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
396 png_ptr->chunk_name != 0)
397 png_chunk_warning(png_ptr, error_message);
398 else
399 # endif
400 png_warning(png_ptr, error_message);
401 }
402
403 else
404 {
405 # ifdef PNG_READ_SUPPORTED
406 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
407 png_ptr->chunk_name != 0)
408 png_chunk_error(png_ptr, error_message);
409 else
410 # endif
411 png_error(png_ptr, error_message);
412 }
413
414 # ifndef PNG_ERROR_TEXT_SUPPORTED
415 PNG_UNUSED(error_message)
416 # endif
417 }
418
419 void /* PRIVATE */
420 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
421 {
422 if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
423 png_warning(png_ptr, error_message);
424 else
425 png_error(png_ptr, error_message);
426
427 # ifndef PNG_ERROR_TEXT_SUPPORTED
428 PNG_UNUSED(error_message)
429 # endif
430 }
431
432 void /* PRIVATE */
433 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
434 {
435 if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
436 png_warning(png_ptr, error_message);
437 else
438 png_error(png_ptr, error_message);
439
440 # ifndef PNG_ERROR_TEXT_SUPPORTED
441 PNG_UNUSED(error_message)
442 # endif
443 }
444 #endif /* BENIGN_ERRORS */
445
446 #define PNG_MAX_ERROR_TEXT 196 /* Currently limited by profile_error in png.c */
447 #if defined(PNG_WARNINGS_SUPPORTED) || \
448 (defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))
449 /* These utilities are used internally to build an error message that relates
450 * to the current chunk. The chunk name comes from png_ptr->chunk_name,
451 * which is used to prefix the message. The message is limited in length
452 * to 63 bytes. The name characters are output as hex digits wrapped in []
453 * if the character is invalid.
454 */
455 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
456 static PNG_CONST char png_digit[16] = {
457 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
458 'A', 'B', 'C', 'D', 'E', 'F'
459 };
460
461 static void /* PRIVATE */
462 png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
463 error_message)
464 {
465 png_uint_32 chunk_name = png_ptr->chunk_name;
466 int iout = 0, ishift = 24;
467
468 while (ishift >= 0)
469 {
470 int c = (int)(chunk_name >> ishift) & 0xff;
471
472 ishift -= 8;
473 if (isnonalpha(c) != 0)
474 {
475 buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
476 buffer[iout++] = png_digit[(c & 0xf0) >> 4];
477 buffer[iout++] = png_digit[c & 0x0f];
478 buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
479 }
480
481 else
482 {
483 buffer[iout++] = (char)c;
484 }
485 }
486
487 if (error_message == NULL)
488 buffer[iout] = '\0';
489
490 else
491 {
492 int iin = 0;
493
494 buffer[iout++] = ':';
495 buffer[iout++] = ' ';
496
497 while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
498 buffer[iout++] = error_message[iin++];
499
500 /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
501 buffer[iout] = '\0';
502 }
503 }
504 #endif /* WARNINGS || ERROR_TEXT */
505
506 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
507 PNG_FUNCTION(void,PNGAPI
508 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
509 PNG_NORETURN)
510 {
511 char msg[18+PNG_MAX_ERROR_TEXT];
512 if (png_ptr == NULL)
513 png_error(png_ptr, error_message);
514
515 else
516 {
517 png_format_buffer(png_ptr, msg, error_message);
518 png_error(png_ptr, msg);
519 }
520 }
521 #endif /* READ && ERROR_TEXT */
522
523 #ifdef PNG_WARNINGS_SUPPORTED
524 void PNGAPI
525 png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
526 {
527 char msg[18+PNG_MAX_ERROR_TEXT];
528 if (png_ptr == NULL)
529 png_warning(png_ptr, warning_message);
530
531 else
532 {
533 png_format_buffer(png_ptr, msg, warning_message);
534 png_warning(png_ptr, msg);
535 }
536 }
537 #endif /* WARNINGS */
538
539 #ifdef PNG_READ_SUPPORTED
540 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
541 void PNGAPI
542 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
543 error_message)
544 {
545 if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
546 png_chunk_warning(png_ptr, error_message);
547
548 else
549 png_chunk_error(png_ptr, error_message);
550
551 # ifndef PNG_ERROR_TEXT_SUPPORTED
552 PNG_UNUSED(error_message)
553 # endif
554 }
555 #endif
556 #endif /* READ */
557
558 void /* PRIVATE */
559 png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
560 {
561 # ifndef PNG_WARNINGS_SUPPORTED
562 PNG_UNUSED(message)
563 # endif
564
565 /* This is always supported, but for just read or just write it
566 * unconditionally does the right thing.
567 */
568 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
569 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
570 # endif
571
572 # ifdef PNG_READ_SUPPORTED
573 {
574 if (error < PNG_CHUNK_ERROR)
575 png_chunk_warning(png_ptr, message);
576
577 else
578 png_chunk_benign_error(png_ptr, message);
579 }
580 # endif
581
582 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
583 else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
584 # endif
585
586 # ifdef PNG_WRITE_SUPPORTED
587 {
588 if (error < PNG_CHUNK_WRITE_ERROR)
589 png_app_warning(png_ptr, message);
590
591 else
592 png_app_error(png_ptr, message);
593 }
594 # endif
595 }
596
597 #ifdef PNG_ERROR_TEXT_SUPPORTED
598 #ifdef PNG_FLOATING_POINT_SUPPORTED
599 PNG_FUNCTION(void,
600 png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
601 {
602 # define fixed_message "fixed point overflow in "
603 # define fixed_message_ln ((sizeof fixed_message)-1)
604 int iin;
605 char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
606 memcpy(msg, fixed_message, fixed_message_ln);
607 iin = 0;
608 if (name != NULL)
609 while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
610 {
611 msg[fixed_message_ln + iin] = name[iin];
612 ++iin;
613 }
614 msg[fixed_message_ln + iin] = 0;
615 png_error(png_ptr, msg);
616 }
617 #endif
618 #endif
619
620 #ifdef PNG_SETJMP_SUPPORTED
621 /* This API only exists if ANSI-C style error handling is used,
622 * otherwise it is necessary for png_default_error to be overridden.
623 */
624 jmp_buf* PNGAPI
625 png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
626 size_t jmp_buf_size)
627 {
628 /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
629 * and it must not change after that. Libpng doesn't care how big the
630 * buffer is, just that it doesn't change.
631 *
632 * If the buffer size is no *larger* than the size of jmp_buf when libpng is
633 * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
634 * semantics that this call will not fail. If the size is larger, however,
635 * the buffer is allocated and this may fail, causing the function to return
636 * NULL.
637 */
638 if (png_ptr == NULL)
639 return NULL;
640
641 if (png_ptr->jmp_buf_ptr == NULL)
642 {
643 png_ptr->jmp_buf_size = 0; /* not allocated */
644
645 if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
646 png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
647
648 else
649 {
650 png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
651 png_malloc_warn(png_ptr, jmp_buf_size));
652
653 if (png_ptr->jmp_buf_ptr == NULL)
654 return NULL; /* new NULL return on OOM */
655
656 png_ptr->jmp_buf_size = jmp_buf_size;
657 }
658 }
659
660 else /* Already allocated: check the size */
661 {
662 size_t size = png_ptr->jmp_buf_size;
663
664 if (size == 0)
665 {
666 size = (sizeof png_ptr->jmp_buf_local);
667 if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
668 {
669 /* This is an internal error in libpng: somehow we have been left
670 * with a stack allocated jmp_buf when the application regained
671 * control. It's always possible to fix this up, but for the moment
672 * this is a png_error because that makes it easy to detect.
673 */
674 png_error(png_ptr, "Libpng jmp_buf still allocated");
675 /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
676 }
677 }
678
679 if (size != jmp_buf_size)
680 {
681 png_warning(png_ptr, "Application jmp_buf size changed");
682 return NULL; /* caller will probably crash: no choice here */
683 }
684 }
685
686 /* Finally fill in the function, now we have a satisfactory buffer. It is
687 * valid to change the function on every call.
688 */
689 png_ptr->longjmp_fn = longjmp_fn;
690 return png_ptr->jmp_buf_ptr;
691 }
692
693 void /* PRIVATE */
694 png_free_jmpbuf(png_structrp png_ptr)
695 {
696 if (png_ptr != NULL)
697 {
698 jmp_buf *jb = png_ptr->jmp_buf_ptr;
699
700 /* A size of 0 is used to indicate a local, stack, allocation of the
701 * pointer; used here and in png.c
702 */
703 if (jb != NULL && png_ptr->jmp_buf_size > 0)
704 {
705
706 /* This stuff is so that a failure to free the error control structure
707 * does not leave libpng in a state with no valid error handling: the
708 * free always succeeds, if there is an error it gets ignored.
709 */
710 if (jb != &png_ptr->jmp_buf_local)
711 {
712 /* Make an internal, libpng, jmp_buf to return here */
713 jmp_buf free_jmp_buf;
714
715 if (!setjmp(free_jmp_buf))
716 {
717 png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
718 png_ptr->jmp_buf_size = 0; /* stack allocation */
719 png_ptr->longjmp_fn = longjmp;
720 png_free(png_ptr, jb); /* Return to setjmp on error */
721 }
722 }
723 }
724
725 /* *Always* cancel everything out: */
726 png_ptr->jmp_buf_size = 0;
727 png_ptr->jmp_buf_ptr = NULL;
728 png_ptr->longjmp_fn = 0;
729 }
730 }
731 #endif
732
733 /* This is the default error handling function. Note that replacements for
734 * this function MUST NOT RETURN, or the program will likely crash. This
735 * function is used by default, or if the program supplies NULL for the
736 * error function pointer in png_set_error_fn().
737 */
738 static PNG_FUNCTION(void /* PRIVATE */,
739 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
740 PNG_NORETURN)
741 {
742 #ifdef PNG_CONSOLE_IO_SUPPORTED
743 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
744 /* Check on NULL only added in 1.5.4 */
745 if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
746 {
747 /* Strip "#nnnn " from beginning of error message. */
748 int offset;
749 char error_number[16];
750 for (offset = 0; offset<15; offset++)
751 {
752 error_number[offset] = error_message[offset + 1];
753 if (error_message[offset] == ' ')
754 break;
755 }
756
757 if ((offset > 1) && (offset < 15))
758 {
759 error_number[offset - 1] = '\0';
760 fprintf(stderr, "libpng error no. %s: %s",
761 error_number, error_message + offset + 1);
762 fprintf(stderr, PNG_STRING_NEWLINE);
763 }
764
765 else
766 {
767 fprintf(stderr, "libpng error: %s, offset=%d",
768 error_message, offset);
769 fprintf(stderr, PNG_STRING_NEWLINE);
770 }
771 }
772 else
773 #endif
774 {
775 fprintf(stderr, "libpng error: %s", error_message ? error_message :
776 "undefined");
777 fprintf(stderr, PNG_STRING_NEWLINE);
778 }
779 #else
780 PNG_UNUSED(error_message) /* Make compiler happy */
781 #endif
782 png_longjmp(png_ptr, 1);
783 }
784
785 PNG_FUNCTION(void,PNGAPI
786 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
787 {
788 #ifdef PNG_SETJMP_SUPPORTED
789 if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
790 png_ptr->jmp_buf_ptr != NULL)
791 png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
792 #else
793 PNG_UNUSED(png_ptr)
794 PNG_UNUSED(val)
795 #endif
796
797 /* If control reaches this point, png_longjmp() must not return. The only
798 * choice is to terminate the whole process (or maybe the thread); to do
799 * this the ANSI-C abort() function is used unless a different method is
800 * implemented by overriding the default configuration setting for
801 * PNG_ABORT().
802 */
803 PNG_ABORT();
804 }
805
806 #ifdef PNG_WARNINGS_SUPPORTED
807 /* This function is called when there is a warning, but the library thinks
808 * it can continue anyway. Replacement functions don't have to do anything
809 * here if you don't want them to. In the default configuration, png_ptr is
810 * not used, but it is passed in case it may be useful.
811 */
812 static void /* PRIVATE */
813 png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
814 {
815 #ifdef PNG_CONSOLE_IO_SUPPORTED
816 # ifdef PNG_ERROR_NUMBERS_SUPPORTED
817 if (*warning_message == PNG_LITERAL_SHARP)
818 {
819 int offset;
820 char warning_number[16];
821 for (offset = 0; offset < 15; offset++)
822 {
823 warning_number[offset] = warning_message[offset + 1];
824 if (warning_message[offset] == ' ')
825 break;
826 }
827
828 if ((offset > 1) && (offset < 15))
829 {
830 warning_number[offset + 1] = '\0';
831 fprintf(stderr, "libpng warning no. %s: %s",
832 warning_number, warning_message + offset);
833 fprintf(stderr, PNG_STRING_NEWLINE);
834 }
835
836 else
837 {
838 fprintf(stderr, "libpng warning: %s",
839 warning_message);
840 fprintf(stderr, PNG_STRING_NEWLINE);
841 }
842 }
843 else
844 # endif
845
846 {
847 fprintf(stderr, "libpng warning: %s", warning_message);
848 fprintf(stderr, PNG_STRING_NEWLINE);
849 }
850 #else
851 PNG_UNUSED(warning_message) /* Make compiler happy */
852 #endif
853 PNG_UNUSED(png_ptr) /* Make compiler happy */
854 }
855 #endif /* WARNINGS */
856
857 /* This function is called when the application wants to use another method
858 * of handling errors and warnings. Note that the error function MUST NOT
859 * return to the calling routine or serious problems will occur. The return
860 * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
861 */
862 void PNGAPI
863 png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
864 png_error_ptr error_fn, png_error_ptr warning_fn)
865 {
866 if (png_ptr == NULL)
867 return;
868
869 png_ptr->error_ptr = error_ptr;
870 png_ptr->error_fn = error_fn;
871 #ifdef PNG_WARNINGS_SUPPORTED
872 png_ptr->warning_fn = warning_fn;
873 #else
874 PNG_UNUSED(warning_fn)
875 #endif
876 }
877
878
879 /* This function returns a pointer to the error_ptr associated with the user
880 * functions. The application should free any memory associated with this
881 * pointer before png_write_destroy and png_read_destroy are called.
882 */
883 png_voidp PNGAPI
884 png_get_error_ptr(png_const_structrp png_ptr)
885 {
886 if (png_ptr == NULL)
887 return NULL;
888
889 return ((png_voidp)png_ptr->error_ptr);
890 }
891
892
893 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
894 void PNGAPI
895 png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
896 {
897 if (png_ptr != NULL)
898 {
899 png_ptr->flags &=
900 ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
901 PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
902 }
903 }
904 #endif
905
906 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
907 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
908 /* Currently the above both depend on SETJMP_SUPPORTED, however it would be
909 * possible to implement without setjmp support just so long as there is some
910 * way to handle the error return here:
911 */
912 PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
913 png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
914 PNG_NORETURN)
915 {
916 const png_const_structrp png_ptr = png_nonconst_ptr;
917 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
918
919 /* An error is always logged here, overwriting anything (typically a warning)
920 * that is already there:
921 */
922 if (image != NULL)
923 {
924 png_safecat(image->message, (sizeof image->message), 0, error_message);
925 image->warning_or_error |= PNG_IMAGE_ERROR;
926
927 /* Retrieve the jmp_buf from within the png_control, making this work for
928 * C++ compilation too is pretty tricky: C++ wants a pointer to the first
929 * element of a jmp_buf, but C doesn't tell us the type of that.
930 */
931 if (image->opaque != NULL && image->opaque->error_buf != NULL)
932 longjmp(png_control_jmp_buf(image->opaque), 1);
933
934 /* Missing longjmp buffer, the following is to help debugging: */
935 {
936 size_t pos = png_safecat(image->message, (sizeof image->message), 0,
937 "bad longjmp: ");
938 png_safecat(image->message, (sizeof image->message), pos,
939 error_message);
940 }
941 }
942
943 /* Here on an internal programming error. */
944 abort();
945 }
946
947 #ifdef PNG_WARNINGS_SUPPORTED
948 void /* PRIVATE */ PNGCBAPI
949 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
950 {
951 const png_const_structrp png_ptr = png_nonconst_ptr;
952 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
953
954 /* A warning is only logged if there is no prior warning or error. */
955 if (image->warning_or_error == 0)
956 {
957 png_safecat(image->message, (sizeof image->message), 0, warning_message);
958 image->warning_or_error |= PNG_IMAGE_WARNING;
959 }
960 }
961 #endif
962
963 int /* PRIVATE */
964 png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
965 {
966 volatile png_imagep image = image_in;
967 volatile int result;
968 volatile png_voidp saved_error_buf;
969 jmp_buf safe_jmpbuf;
970
971 /* Safely execute function(arg) with png_error returning to this function. */
972 saved_error_buf = image->opaque->error_buf;
973 result = setjmp(safe_jmpbuf) == 0;
974
975 if (result != 0)
976 {
977
978 image->opaque->error_buf = safe_jmpbuf;
979 result = function(arg);
980 }
981
982 image->opaque->error_buf = saved_error_buf;
983
984 /* And do the cleanup prior to any failure return. */
985 if (result == 0)
986 png_image_free(image);
987
988 return result;
989 }
990 #endif /* SIMPLIFIED READ || SIMPLIFIED_WRITE */
991 #endif /* READ || WRITE */