src/png/pngerror.c

   1
   2 /* pngerror.c - stub functions for i/o and memory allocation
   3  *
   4  * Last changed in libpng 1.6.1 [March 28, 2013]
   5  * Copyright (c) 1998-2013 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  *
  13  * This file provides a location for all error handling.  Users who
  14  * need special error handling are expected to write replacement functions
  15  * and use png_set_error_fn() to use those functions.  See the instructions
  16  * at each function.
  17  */
  18
  19 #include "pngpriv.h"
  20
  21 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
  22
  23 static 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
  27 static void /* PRIVATE */
  28 png_default_warning PNGARG((png_const_structrp png_ptr,
  29    png_const_charp warning_message));
  30 #endif /* PNG_WARNINGS_SUPPORTED */
  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
  38 PNG_FUNCTION(void,PNGAPI
  39 png_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))
  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)
  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)
  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
  91 PNG_FUNCTION(void,PNGAPI
  92 png_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 /* PNG_ERROR_TEXT_SUPPORTED */
 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  */
 111 size_t
 112 png_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  */
 132 png_charp
 133 png_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 || 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             /* FALL THROUGH */
 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             /* FALL THROUGH */
 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) if (count == 5) if (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)
 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  */
 215 void PNGAPI
 216 png_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))
 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  */
 246 void
 247 png_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
 254 void
 255 png_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
 262 void
 263 png_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
 283 void
 284 png_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 /* PNG_WARNINGS_SUPPORTED */
 359
 360 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 361 void PNGAPI
 362 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
 363 {
 364    if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
 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
 387 void /* PRIVATE */
 388 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
 389 {
 390   if (png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN)
 391      png_warning(png_ptr, error_message);
 392   else
 393      png_error(png_ptr, error_message);
 394 }
 395
 396 void /* PRIVATE */
 397 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
 398 {
 399   if (png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN)
 400      png_warning(png_ptr, error_message);
 401   else
 402      png_error(png_ptr, error_message);
 403 }
 404 #endif /* BENIGN_ERRORS */
 405
 406 /* These utilities are used internally to build an error message that relates
 407  * to the current chunk.  The chunk name comes from png_ptr->chunk_name,
 408  * this is used to prefix the message.  The message is limited in length
 409  * to 63 bytes, the name characters are output as hex digits wrapped in []
 410  * if the character is invalid.
 411  */
 412 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
 413 static PNG_CONST char png_digit[16] = {
 414    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
 415    'A', 'B', 'C', 'D', 'E', 'F'
 416 };
 417
 418 #define PNG_MAX_ERROR_TEXT 196 /* Currently limited be profile_error in png.c */
 419 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
 420 static void /* PRIVATE */
 421 png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
 422     error_message)
 423 {
 424    png_uint_32 chunk_name = png_ptr->chunk_name;
 425    int iout = 0, ishift = 24;
 426
 427    while (ishift >= 0)
 428    {
 429       int c = (int)(chunk_name >> ishift) & 0xff;
 430
 431       ishift -= 8;
 432       if (isnonalpha(c))
 433       {
 434          buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
 435          buffer[iout++] = png_digit[(c & 0xf0) >> 4];
 436          buffer[iout++] = png_digit[c & 0x0f];
 437          buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
 438       }
 439
 440       else
 441       {
 442          buffer[iout++] = (char)c;
 443       }
 444    }
 445
 446    if (error_message == NULL)
 447       buffer[iout] = '\0';
 448
 449    else
 450    {
 451       int iin = 0;
 452
 453       buffer[iout++] = ':';
 454       buffer[iout++] = ' ';
 455
 456       while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
 457          buffer[iout++] = error_message[iin++];
 458
 459       /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
 460       buffer[iout] = '\0';
 461    }
 462 }
 463 #endif /* PNG_WARNINGS_SUPPORTED || PNG_ERROR_TEXT_SUPPORTED */
 464
 465 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
 466 PNG_FUNCTION(void,PNGAPI
 467 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
 468    PNG_NORETURN)
 469 {
 470    char msg[18+PNG_MAX_ERROR_TEXT];
 471    if (png_ptr == NULL)
 472       png_error(png_ptr, error_message);
 473
 474    else
 475    {
 476       png_format_buffer(png_ptr, msg, error_message);
 477       png_error(png_ptr, msg);
 478    }
 479 }
 480 #endif /* PNG_READ_SUPPORTED && PNG_ERROR_TEXT_SUPPORTED */
 481
 482 #ifdef PNG_WARNINGS_SUPPORTED
 483 void PNGAPI
 484 png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 485 {
 486    char msg[18+PNG_MAX_ERROR_TEXT];
 487    if (png_ptr == NULL)
 488       png_warning(png_ptr, warning_message);
 489
 490    else
 491    {
 492       png_format_buffer(png_ptr, msg, warning_message);
 493       png_warning(png_ptr, msg);
 494    }
 495 }
 496 #endif /* PNG_WARNINGS_SUPPORTED */
 497
 498 #ifdef PNG_READ_SUPPORTED
 499 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 500 void PNGAPI
 501 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
 502     error_message)
 503 {
 504    if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
 505       png_chunk_warning(png_ptr, error_message);
 506
 507    else
 508       png_chunk_error(png_ptr, error_message);
 509 }
 510 #endif
 511 #endif /* PNG_READ_SUPPORTED */
 512
 513 void /* PRIVATE */
 514 png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
 515 {
 516    /* This is always supported, but for just read or just write it
 517     * unconditionally does the right thing.
 518     */
 519 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
 520       if (png_ptr->mode & PNG_IS_READ_STRUCT)
 521 #  endif
 522
 523 #  ifdef PNG_READ_SUPPORTED
 524       {
 525          if (error < PNG_CHUNK_ERROR)
 526             png_chunk_warning(png_ptr, message);
 527
 528          else
 529             png_chunk_benign_error(png_ptr, message);
 530       }
 531 #  endif
 532
 533 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
 534       else if (!(png_ptr->mode & PNG_IS_READ_STRUCT))
 535 #  endif
 536
 537 #  ifdef PNG_WRITE_SUPPORTED
 538       {
 539          if (error < PNG_CHUNK_WRITE_ERROR)
 540             png_app_warning(png_ptr, message);
 541
 542          else
 543             png_app_error(png_ptr, message);
 544       }
 545 #  endif
 546 }
 547
 548 #ifdef PNG_ERROR_TEXT_SUPPORTED
 549 #ifdef PNG_FLOATING_POINT_SUPPORTED
 550 PNG_FUNCTION(void,
 551 png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
 552 {
 553 #  define fixed_message "fixed point overflow in "
 554 #  define fixed_message_ln ((sizeof fixed_message)-1)
 555    int  iin;
 556    char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
 557    memcpy(msg, fixed_message, fixed_message_ln);
 558    iin = 0;
 559    if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
 560    {
 561       msg[fixed_message_ln + iin] = name[iin];
 562       ++iin;
 563    }
 564    msg[fixed_message_ln + iin] = 0;
 565    png_error(png_ptr, msg);
 566 }
 567 #endif
 568 #endif
 569
 570 #ifdef PNG_SETJMP_SUPPORTED
 571 /* This API only exists if ANSI-C style error handling is used,
 572  * otherwise it is necessary for png_default_error to be overridden.
 573  */
 574 jmp_buf* PNGAPI
 575 png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
 576     size_t jmp_buf_size)
 577 {
 578    /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
 579     * and it must not change after that.  Libpng doesn't care how big the
 580     * buffer is, just that it doesn't change.
 581     *
 582     * If the buffer size is no *larger* than the size of jmp_buf when libpng is
 583     * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
 584     * semantics that this call will not fail.  If the size is larger, however,
 585     * the buffer is allocated and this may fail, causing the function to return
 586     * NULL.
 587     */
 588    if (png_ptr == NULL)
 589       return NULL;
 590
 591    if (png_ptr->jmp_buf_ptr == NULL)
 592    {
 593       png_ptr->jmp_buf_size = 0; /* not allocated */
 594
 595       if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
 596          png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
 597
 598       else
 599       {
 600          png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
 601             png_malloc_warn(png_ptr, jmp_buf_size));
 602
 603          if (png_ptr->jmp_buf_ptr == NULL)
 604             return NULL; /* new NULL return on OOM */
 605
 606          png_ptr->jmp_buf_size = jmp_buf_size;
 607       }
 608    }
 609
 610    else /* Already allocated: check the size */
 611    {
 612       size_t size = png_ptr->jmp_buf_size;
 613
 614       if (size == 0)
 615       {
 616          size = (sizeof png_ptr->jmp_buf_local);
 617          if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
 618          {
 619             /* This is an internal error in libpng: somehow we have been left
 620              * with a stack allocated jmp_buf when the application regained
 621              * control.  It's always possible to fix this up, but for the moment
 622              * this is a png_error because that makes it easy to detect.
 623              */
 624             png_error(png_ptr, "Libpng jmp_buf still allocated");
 625             /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
 626          }
 627       }
 628
 629       if (size != jmp_buf_size)
 630       {
 631          png_warning(png_ptr, "Application jmp_buf size changed");
 632          return NULL; /* caller will probably crash: no choice here */
 633       }
 634    }
 635
 636    /* Finally fill in the function, now we have a satisfactory buffer. It is
 637     * valid to change the function on every call.
 638     */
 639    png_ptr->longjmp_fn = longjmp_fn;
 640    return png_ptr->jmp_buf_ptr;
 641 }
 642
 643 void /* PRIVATE */
 644 png_free_jmpbuf(png_structrp png_ptr)
 645 {
 646    if (png_ptr != NULL)
 647    {
 648       jmp_buf *jb = png_ptr->jmp_buf_ptr;
 649
 650       /* A size of 0 is used to indicate a local, stack, allocation of the
 651        * pointer; used here and in png.c
 652        */
 653       if (jb != NULL && png_ptr->jmp_buf_size > 0)
 654       {
 655
 656          /* This stuff is so that a failure to free the error control structure
 657           * does not leave libpng in a state with no valid error handling: the
 658           * free always succeeds, if there is an error it gets ignored.
 659           */
 660          if (jb != &png_ptr->jmp_buf_local)
 661          {
 662             /* Make an internal, libpng, jmp_buf to return here */
 663             jmp_buf free_jmp_buf;
 664
 665             if (!setjmp(free_jmp_buf))
 666             {
 667                png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
 668                png_ptr->jmp_buf_size = 0; /* stack allocation */
 669                png_ptr->longjmp_fn = longjmp;
 670                png_free(png_ptr, jb); /* Return to setjmp on error */
 671             }
 672          }
 673       }
 674
 675       /* *Always* cancel everything out: */
 676       png_ptr->jmp_buf_size = 0;
 677       png_ptr->jmp_buf_ptr = NULL;
 678       png_ptr->longjmp_fn = 0;
 679    }
 680 }
 681 #endif
 682
 683 /* This is the default error handling function.  Note that replacements for
 684  * this function MUST NOT RETURN, or the program will likely crash.  This
 685  * function is used by default, or if the program supplies NULL for the
 686  * error function pointer in png_set_error_fn().
 687  */
 688 static PNG_FUNCTION(void /* PRIVATE */,
 689 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
 690    PNG_NORETURN)
 691 {
 692 #ifdef PNG_CONSOLE_IO_SUPPORTED
 693 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 694    /* Check on NULL only added in 1.5.4 */
 695    if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
 696    {
 697       /* Strip "#nnnn " from beginning of error message. */
 698       int offset;
 699       char error_number[16];
 700       for (offset = 0; offset<15; offset++)
 701       {
 702          error_number[offset] = error_message[offset + 1];
 703          if (error_message[offset] == ' ')
 704             break;
 705       }
 706
 707       if ((offset > 1) && (offset < 15))
 708       {
 709          error_number[offset - 1] = '\0';
 710          fprintf(stderr, "libpng error no. %s: %s",
 711              error_number, error_message + offset + 1);
 712          fprintf(stderr, PNG_STRING_NEWLINE);
 713       }
 714
 715       else
 716       {
 717          fprintf(stderr, "libpng error: %s, offset=%d",
 718              error_message, offset);
 719          fprintf(stderr, PNG_STRING_NEWLINE);
 720       }
 721    }
 722    else
 723 #endif
 724    {
 725       fprintf(stderr, "libpng error: %s", error_message ? error_message :
 726          "undefined");
 727       fprintf(stderr, PNG_STRING_NEWLINE);
 728    }
 729 #else
 730    PNG_UNUSED(error_message) /* Make compiler happy */
 731 #endif
 732    png_longjmp(png_ptr, 1);
 733 }
 734
 735 PNG_FUNCTION(void,PNGAPI
 736 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
 737 {
 738 #ifdef PNG_SETJMP_SUPPORTED
 739    if (png_ptr && png_ptr->longjmp_fn && png_ptr->jmp_buf_ptr)
 740       png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
 741 #endif
 742
 743    /* Here if not setjmp support or if png_ptr is null. */
 744    PNG_ABORT();
 745 }
 746
 747 #ifdef PNG_WARNINGS_SUPPORTED
 748 /* This function is called when there is a warning, but the library thinks
 749  * it can continue anyway.  Replacement functions don't have to do anything
 750  * here if you don't want them to.  In the default configuration, png_ptr is
 751  * not used, but it is passed in case it may be useful.
 752  */
 753 static void /* PRIVATE */
 754 png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
 755 {
 756 #ifdef PNG_CONSOLE_IO_SUPPORTED
 757 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
 758    if (*warning_message == PNG_LITERAL_SHARP)
 759    {
 760       int offset;
 761       char warning_number[16];
 762       for (offset = 0; offset < 15; offset++)
 763       {
 764          warning_number[offset] = warning_message[offset + 1];
 765          if (warning_message[offset] == ' ')
 766             break;
 767       }
 768
 769       if ((offset > 1) && (offset < 15))
 770       {
 771          warning_number[offset + 1] = '\0';
 772          fprintf(stderr, "libpng warning no. %s: %s",
 773              warning_number, warning_message + offset);
 774          fprintf(stderr, PNG_STRING_NEWLINE);
 775       }
 776
 777       else
 778       {
 779          fprintf(stderr, "libpng warning: %s",
 780              warning_message);
 781          fprintf(stderr, PNG_STRING_NEWLINE);
 782       }
 783    }
 784    else
 785 #  endif
 786
 787    {
 788       fprintf(stderr, "libpng warning: %s", warning_message);
 789       fprintf(stderr, PNG_STRING_NEWLINE);
 790    }
 791 #else
 792    PNG_UNUSED(warning_message) /* Make compiler happy */
 793 #endif
 794    PNG_UNUSED(png_ptr) /* Make compiler happy */
 795 }
 796 #endif /* PNG_WARNINGS_SUPPORTED */
 797
 798 /* This function is called when the application wants to use another method
 799  * of handling errors and warnings.  Note that the error function MUST NOT
 800  * return to the calling routine or serious problems will occur.  The return
 801  * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
 802  */
 803 void PNGAPI
 804 png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
 805     png_error_ptr error_fn, png_error_ptr warning_fn)
 806 {
 807    if (png_ptr == NULL)
 808       return;
 809
 810    png_ptr->error_ptr = error_ptr;
 811    png_ptr->error_fn = error_fn;
 812 #ifdef PNG_WARNINGS_SUPPORTED
 813    png_ptr->warning_fn = warning_fn;
 814 #else
 815    PNG_UNUSED(warning_fn)
 816 #endif
 817 }
 818
 819
 820 /* This function returns a pointer to the error_ptr associated with the user
 821  * functions.  The application should free any memory associated with this
 822  * pointer before png_write_destroy and png_read_destroy are called.
 823  */
 824 png_voidp PNGAPI
 825 png_get_error_ptr(png_const_structrp png_ptr)
 826 {
 827    if (png_ptr == NULL)
 828       return NULL;
 829
 830    return ((png_voidp)png_ptr->error_ptr);
 831 }
 832
 833
 834 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 835 void PNGAPI
 836 png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
 837 {
 838    if (png_ptr != NULL)
 839    {
 840       png_ptr->flags &=
 841          ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
 842          PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
 843    }
 844 }
 845 #endif
 846
 847 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
 848    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
 849    /* Currently the above both depend on SETJMP_SUPPORTED, however it would be
 850     * possible to implement without setjmp support just so long as there is some
 851     * way to handle the error return here:
 852     */
 853 PNG_FUNCTION(void /* PRIVATE */,
 854 png_safe_error,(png_structp png_nonconst_ptr, png_const_charp error_message),
 855    PNG_NORETURN)
 856 {
 857    const png_const_structrp png_ptr = png_nonconst_ptr;
 858    png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
 859
 860    /* An error is always logged here, overwriting anything (typically a warning)
 861     * that is already there:
 862     */
 863    if (image != NULL)
 864    {
 865       png_safecat(image->message, (sizeof image->message), 0, error_message);
 866       image->warning_or_error |= PNG_IMAGE_ERROR;
 867
 868       /* Retrieve the jmp_buf from within the png_control, making this work for
 869        * C++ compilation too is pretty tricky: C++ wants a pointer to the first
 870        * element of a jmp_buf, but C doesn't tell us the type of that.
 871        */
 872       if (image->opaque != NULL && image->opaque->error_buf != NULL)
 873          longjmp(png_control_jmp_buf(image->opaque), 1);
 874
 875       /* Missing longjmp buffer, the following is to help debugging: */
 876       {
 877          size_t pos = png_safecat(image->message, (sizeof image->message), 0,
 878             "bad longjmp: ");
 879          png_safecat(image->message, (sizeof image->message), pos,
 880              error_message);
 881       }
 882    }
 883
 884    /* Here on an internal programming error. */
 885    abort();
 886 }
 887
 888 #ifdef PNG_WARNINGS_SUPPORTED
 889 void /* PRIVATE */
 890 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
 891 {
 892    const png_const_structrp png_ptr = png_nonconst_ptr;
 893    png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
 894
 895    /* A warning is only logged if there is no prior warning or error. */
 896    if (image->warning_or_error == 0)
 897    {
 898       png_safecat(image->message, (sizeof image->message), 0, warning_message);
 899       image->warning_or_error |= PNG_IMAGE_WARNING;
 900    }
 901 }
 902 #endif
 903
 904 int /* PRIVATE */
 905 png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
 906 {
 907    volatile png_imagep image = image_in;
 908    volatile int result;
 909    volatile png_voidp saved_error_buf;
 910    jmp_buf safe_jmpbuf;
 911
 912    /* Safely execute function(arg) with png_error returning to this function. */
 913    saved_error_buf = image->opaque->error_buf;
 914    result = setjmp(safe_jmpbuf) == 0;
 915
 916    if (result)
 917    {
 918
 919       image->opaque->error_buf = safe_jmpbuf;
 920       result = function(arg);
 921    }
 922
 923    image->opaque->error_buf = saved_error_buf;
 924
 925    /* And do the cleanup prior to any failure return. */
 926    if (!result)
 927       png_image_free(image);
 928
 929    return result;
 930 }
 931 #endif /* SIMPLIFIED READ/WRITE */
 932 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */