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 1.6.26 [October 20, 2016]
33 * Copyright (c) 1998-2002,2004,2006-2016 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
51static 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
55static void /* PRIVATE */
56png_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
66PNG_FUNCTION(void,PNGAPI
67png_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
119PNG_FUNCTION(void,PNGAPI
120png_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 */
139size_t
140png_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 */
160png_charp
161png_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 */
243void PNGAPI
244png_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 */
274void
275png_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
282void
283png_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
290void
291png_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
311void
312png_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
389void PNGAPI
390png_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
419void /* PRIVATE */
420png_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
432void /* PRIVATE */
433png_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))
456static 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
461static void /* PRIVATE */
462png_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)
507PNG_FUNCTION(void,PNGAPI
508png_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
524void PNGAPI
525png_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
541void PNGAPI
542png_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
558void /* PRIVATE */
559png_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
599PNG_FUNCTION(void,
600png_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   unsigned 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 */
624jmp_buf* PNGAPI
625png_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
693void /* PRIVATE */
694png_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 */
738static PNG_FUNCTION(void /* PRIVATE */,
739png_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
785PNG_FUNCTION(void,PNGAPI
786png_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 */
812static void /* PRIVATE */
813png_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 */
862void PNGAPI
863png_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 */
883png_voidp PNGAPI
884png_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
894void PNGAPI
895png_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    */
912PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
913png_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
948void /* PRIVATE */ PNGCBAPI
949png_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
963int /* PRIVATE */
964png_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 */
992