workbench/libs/png/pngerror.c

   1
   2 /* pngerror.c - stub functions for i/o and memory allocation
   3  *
   4  * Last changed in libpng 1.5.8 [February 1, 2011]
   5  * Copyright (c) 1998-2012 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_structp 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_structp 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_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
  40 {
  41 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
  42    char msg[16];
  43    if (png_ptr != NULL)
  44    {
  45       if (png_ptr->flags&
  46          (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
  47       {
  48          if (*error_message == PNG_LITERAL_SHARP)
  49          {
  50             /* Strip "#nnnn " from beginning of error message. */
  51             int offset;
  52             for (offset = 1; offset<15; offset++)
  53                if (error_message[offset] == ' ')
  54                   break;
  55
  56             if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
  57             {
  58                int i;
  59                for (i = 0; i < offset - 1; i++)
  60                   msg[i] = error_message[i + 1];
  61                msg[i - 1] = '\0';
  62                error_message = msg;
  63             }
  64
  65             else
  66                error_message += offset;
  67       }
  68
  69       else
  70       {
  71          if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
  72          {
  73             msg[0] = '0';
  74             msg[1] = '\0';
  75             error_message = msg;
  76          }
  77        }
  78      }
  79    }
  80 #endif
  81    if (png_ptr != NULL && png_ptr->error_fn != NULL)
  82       (*(png_ptr->error_fn))(png_ptr, error_message);
  83
  84    /* If the custom handler doesn't exist, or if it returns,
  85       use the default handler, which will not return. */
  86    png_default_error(png_ptr, error_message);
  87 }
  88 #else
  89 PNG_FUNCTION(void,PNGAPI
  90 png_err,(png_structp png_ptr),PNG_NORETURN)
  91 {
  92    /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
  93     * erroneously as '\0', instead of the empty string "".  This was
  94     * apparently an error, introduced in libpng-1.2.20, and png_default_error
  95     * will crash in this case.
  96     */
  97    if (png_ptr != NULL && png_ptr->error_fn != NULL)
  98       (*(png_ptr->error_fn))(png_ptr, "");
  99
 100    /* If the custom handler doesn't exist, or if it returns,
 101       use the default handler, which will not return. */
 102    png_default_error(png_ptr, "");
 103 }
 104 #endif /* PNG_ERROR_TEXT_SUPPORTED */
 105
 106 /* Utility to safely appends strings to a buffer.  This never errors out so
 107  * error checking is not required in the caller.
 108  */
 109 size_t
 110 png_safecat(png_charp buffer, size_t bufsize, size_t pos,
 111    png_const_charp string)
 112 {
 113    if (buffer != NULL && pos < bufsize)
 114    {
 115       if (string != NULL)
 116          while (*string != '\0' && pos < bufsize-1)
 117            buffer[pos++] = *string++;
 118
 119       buffer[pos] = '\0';
 120    }
 121
 122    return pos;
 123 }
 124
 125 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
 126 /* Utility to dump an unsigned value into a buffer, given a start pointer and
 127  * and end pointer (which should point just *beyond* the end of the buffer!)
 128  * Returns the pointer to the start of the formatted string.
 129  */
 130 png_charp
 131 png_format_number(png_const_charp start, png_charp end, int format,
 132    png_alloc_size_t number)
 133 {
 134    int count = 0;    /* number of digits output */
 135    int mincount = 1; /* minimum number required */
 136    int output = 0;   /* digit output (for the fixed point format) */
 137
 138    *--end = '\0';
 139
 140    /* This is written so that the loop always runs at least once, even with
 141     * number zero.
 142     */
 143    while (end > start && (number != 0 || count < mincount))
 144    {
 145
 146       static const char digits[] = "0123456789ABCDEF";
 147
 148       switch (format)
 149       {
 150          case PNG_NUMBER_FORMAT_fixed:
 151             /* Needs five digits (the fraction) */
 152             mincount = 5;
 153             if (output || number % 10 != 0)
 154             {
 155                *--end = digits[number % 10];
 156                output = 1;
 157             }
 158             number /= 10;
 159             break;
 160
 161          case PNG_NUMBER_FORMAT_02u:
 162             /* Expects at least 2 digits. */
 163             mincount = 2;
 164             /* fall through */
 165
 166          case PNG_NUMBER_FORMAT_u:
 167             *--end = digits[number % 10];
 168             number /= 10;
 169             break;
 170
 171          case PNG_NUMBER_FORMAT_02x:
 172             /* This format expects at least two digits */
 173             mincount = 2;
 174             /* fall through */
 175
 176          case PNG_NUMBER_FORMAT_x:
 177             *--end = digits[number & 0xf];
 178             number >>= 4;
 179             break;
 180
 181          default: /* an error */
 182             number = 0;
 183             break;
 184       }
 185
 186       /* Keep track of the number of digits added */
 187       ++count;
 188
 189       /* Float a fixed number here: */
 190       if (format == PNG_NUMBER_FORMAT_fixed) if (count == 5) if (end > start)
 191       {
 192          /* End of the fraction, but maybe nothing was output?  In that case
 193           * drop the decimal point.  If the number is a true zero handle that
 194           * here.
 195           */
 196          if (output)
 197             *--end = '.';
 198          else if (number == 0) /* and !output */
 199             *--end = '0';
 200       }
 201    }
 202
 203    return end;
 204 }
 205 #endif
 206
 207 #ifdef PNG_WARNINGS_SUPPORTED
 208 /* This function is called whenever there is a non-fatal error.  This function
 209  * should not be changed.  If there is a need to handle warnings differently,
 210  * you should supply a replacement warning function and use
 211  * png_set_error_fn() to replace the warning function at run-time.
 212  */
 213 void PNGAPI
 214 png_warning(png_structp png_ptr, png_const_charp warning_message)
 215 {
 216    int offset = 0;
 217    if (png_ptr != NULL)
 218    {
 219 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 220    if (png_ptr->flags&
 221        (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
 222 #endif
 223       {
 224          if (*warning_message == PNG_LITERAL_SHARP)
 225          {
 226             for (offset = 1; offset < 15; offset++)
 227                if (warning_message[offset] == ' ')
 228                   break;
 229          }
 230       }
 231    }
 232    if (png_ptr != NULL && png_ptr->warning_fn != NULL)
 233       (*(png_ptr->warning_fn))(png_ptr, warning_message + offset);
 234    else
 235       png_default_warning(png_ptr, warning_message + offset);
 236 }
 237
 238 /* These functions support 'formatted' warning messages with up to
 239  * PNG_WARNING_PARAMETER_COUNT parameters.  In the format string the parameter
 240  * is introduced by @<number>, where 'number' starts at 1.  This follows the
 241  * standard established by X/Open for internationalizable error messages.
 242  */
 243 void
 244 png_warning_parameter(png_warning_parameters p, int number,
 245    png_const_charp string)
 246 {
 247    if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
 248       (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
 249 }
 250
 251 void
 252 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
 253    png_alloc_size_t value)
 254 {
 255    char buffer[PNG_NUMBER_BUFFER_SIZE];
 256    png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
 257 }
 258
 259 void
 260 png_warning_parameter_signed(png_warning_parameters p, int number, int format,
 261    png_int_32 value)
 262 {
 263    png_alloc_size_t u;
 264    png_charp str;
 265    char buffer[PNG_NUMBER_BUFFER_SIZE];
 266
 267    /* Avoid overflow by doing the negate in a png_alloc_size_t: */
 268    u = (png_alloc_size_t)value;
 269    if (value < 0)
 270       u = ~u + 1;
 271
 272    str = PNG_FORMAT_NUMBER(buffer, format, u);
 273
 274    if (value < 0 && str > buffer)
 275       *--str = '-';
 276
 277    png_warning_parameter(p, number, str);
 278 }
 279
 280 void
 281 png_formatted_warning(png_structp png_ptr, png_warning_parameters p,
 282    png_const_charp message)
 283 {
 284    /* The internal buffer is just 192 bytes - enough for all our messages,
 285     * overflow doesn't happen because this code checks!  If someone figures
 286     * out how to send us a message longer than 192 bytes, all that will
 287     * happen is that the message will be truncated appropriately.
 288     */
 289    size_t i = 0; /* Index in the msg[] buffer: */
 290    char msg[192];
 291
 292    /* Each iteration through the following loop writes at most one character
 293     * to msg[i++] then returns here to validate that there is still space for
 294     * the trailing '\0'.  It may (in the case of a parameter) read more than
 295     * one character from message[]; it must check for '\0' and continue to the
 296     * test if it finds the end of string.
 297     */
 298    while (i<(sizeof msg)-1 && *message != '\0')
 299    {
 300       /* '@' at end of string is now just printed (previously it was skipped);
 301        * it is an error in the calling code to terminate the string with @.
 302        */
 303       if (p != NULL && *message == '@' && message[1] != '\0')
 304       {
 305          int parameter_char = *++message; /* Consume the '@' */
 306          static const char valid_parameters[] = "123456789";
 307          int parameter = 0;
 308
 309          /* Search for the parameter digit, the index in the string is the
 310           * parameter to use.
 311           */
 312          while (valid_parameters[parameter] != parameter_char &&
 313             valid_parameters[parameter] != '\0')
 314             ++parameter;
 315
 316          /* If the parameter digit is out of range it will just get printed. */
 317          if (parameter < PNG_WARNING_PARAMETER_COUNT)
 318          {
 319             /* Append this parameter */
 320             png_const_charp parm = p[parameter];
 321             png_const_charp pend = p[parameter] + (sizeof p[parameter]);
 322
 323             /* No need to copy the trailing '\0' here, but there is no guarantee
 324              * that parm[] has been initialized, so there is no guarantee of a
 325              * trailing '\0':
 326              */
 327             while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
 328                msg[i++] = *parm++;
 329
 330             /* Consume the parameter digit too: */
 331             ++message;
 332             continue;
 333          }
 334
 335          /* else not a parameter and there is a character after the @ sign; just
 336           * copy that.  This is known not to be '\0' because of the test above.
 337           */
 338       }
 339
 340       /* At this point *message can't be '\0', even in the bad parameter case
 341        * above where there is a lone '@' at the end of the message string.
 342        */
 343       msg[i++] = *message++;
 344    }
 345
 346    /* i is always less than (sizeof msg), so: */
 347    msg[i] = '\0';
 348
 349    /* And this is the formatted message, it may be larger than
 350     * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these are
 351     * not (currently) formatted.
 352     */
 353    png_warning(png_ptr, msg);
 354 }
 355 #endif /* PNG_WARNINGS_SUPPORTED */
 356
 357 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 358 void PNGAPI
 359 png_benign_error(png_structp png_ptr, png_const_charp error_message)
 360 {
 361   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
 362      png_warning(png_ptr, error_message);
 363   else
 364      png_error(png_ptr, error_message);
 365 }
 366 #endif
 367
 368 /* These utilities are used internally to build an error message that relates
 369  * to the current chunk.  The chunk name comes from png_ptr->chunk_name,
 370  * this is used to prefix the message.  The message is limited in length
 371  * to 63 bytes, the name characters are output as hex digits wrapped in []
 372  * if the character is invalid.
 373  */
 374 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
 375 static PNG_CONST char png_digit[16] = {
 376    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
 377    'A', 'B', 'C', 'D', 'E', 'F'
 378 };
 379
 380 #define PNG_MAX_ERROR_TEXT 64
 381 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
 382 static void /* PRIVATE */
 383 png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
 384     error_message)
 385 {
 386    png_uint_32 chunk_name = png_ptr->chunk_name;
 387    int iout = 0, ishift = 24;
 388
 389    while (ishift >= 0)
 390    {
 391       int c = (int)(chunk_name >> ishift) & 0xff;
 392
 393       ishift -= 8;
 394       if (isnonalpha(c))
 395       {
 396          buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
 397          buffer[iout++] = png_digit[(c & 0xf0) >> 4];
 398          buffer[iout++] = png_digit[c & 0x0f];
 399          buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
 400       }
 401
 402       else
 403       {
 404          buffer[iout++] = (char)c;
 405       }
 406    }
 407
 408    if (error_message == NULL)
 409       buffer[iout] = '\0';
 410
 411    else
 412    {
 413       int iin = 0;
 414
 415       buffer[iout++] = ':';
 416       buffer[iout++] = ' ';
 417
 418       while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
 419          buffer[iout++] = error_message[iin++];
 420
 421       /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
 422       buffer[iout] = '\0';
 423    }
 424 }
 425 #endif /* PNG_WARNINGS_SUPPORTED || PNG_ERROR_TEXT_SUPPORTED */
 426
 427 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
 428 PNG_FUNCTION(void,PNGAPI
 429 png_chunk_error,(png_structp png_ptr, png_const_charp error_message),
 430    PNG_NORETURN)
 431 {
 432    char msg[18+PNG_MAX_ERROR_TEXT];
 433    if (png_ptr == NULL)
 434       png_error(png_ptr, error_message);
 435
 436    else
 437    {
 438       png_format_buffer(png_ptr, msg, error_message);
 439       png_error(png_ptr, msg);
 440    }
 441 }
 442 #endif /* PNG_READ_SUPPORTED && PNG_ERROR_TEXT_SUPPORTED */
 443
 444 #ifdef PNG_WARNINGS_SUPPORTED
 445 void PNGAPI
 446 png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
 447 {
 448    char msg[18+PNG_MAX_ERROR_TEXT];
 449    if (png_ptr == NULL)
 450       png_warning(png_ptr, warning_message);
 451
 452    else
 453    {
 454       png_format_buffer(png_ptr, msg, warning_message);
 455       png_warning(png_ptr, msg);
 456    }
 457 }
 458 #endif /* PNG_WARNINGS_SUPPORTED */
 459
 460 #ifdef PNG_READ_SUPPORTED
 461 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
 462 void PNGAPI
 463 png_chunk_benign_error(png_structp png_ptr, png_const_charp error_message)
 464 {
 465    if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
 466       png_chunk_warning(png_ptr, error_message);
 467
 468    else
 469       png_chunk_error(png_ptr, error_message);
 470 }
 471 #endif
 472 #endif /* PNG_READ_SUPPORTED */
 473
 474 #ifdef PNG_ERROR_TEXT_SUPPORTED
 475 #ifdef PNG_FLOATING_POINT_SUPPORTED
 476 PNG_FUNCTION(void,
 477 png_fixed_error,(png_structp png_ptr, png_const_charp name),PNG_NORETURN)
 478 {
 479 #  define fixed_message "fixed point overflow in "
 480 #  define fixed_message_ln ((sizeof fixed_message)-1)
 481    int  iin;
 482    char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
 483    png_memcpy(msg, fixed_message, fixed_message_ln);
 484    iin = 0;
 485    if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
 486    {
 487       msg[fixed_message_ln + iin] = name[iin];
 488       ++iin;
 489    }
 490    msg[fixed_message_ln + iin] = 0;
 491    png_error(png_ptr, msg);
 492 }
 493 #endif
 494 #endif
 495
 496 #ifdef PNG_SETJMP_SUPPORTED
 497 /* This API only exists if ANSI-C style error handling is used,
 498  * otherwise it is necessary for png_default_error to be overridden.
 499  */
 500 jmp_buf* PNGAPI
 501 png_set_longjmp_fn(png_structp png_ptr, png_longjmp_ptr longjmp_fn,
 502     size_t jmp_buf_size)
 503 {
 504    if (png_ptr == NULL || jmp_buf_size != png_sizeof(jmp_buf))
 505       return NULL;
 506
 507    png_ptr->longjmp_fn = longjmp_fn;
 508    return &png_ptr->longjmp_buffer;
 509 }
 510 #endif
 511
 512 /* This is the default error handling function.  Note that replacements for
 513  * this function MUST NOT RETURN, or the program will likely crash.  This
 514  * function is used by default, or if the program supplies NULL for the
 515  * error function pointer in png_set_error_fn().
 516  */
 517 static PNG_FUNCTION(void /* PRIVATE */,
 518 png_default_error,(png_structp png_ptr, png_const_charp error_message),
 519    PNG_NORETURN)
 520 {
 521 #ifdef PNG_CONSOLE_IO_SUPPORTED
 522 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 523    /* Check on NULL only added in 1.5.4 */
 524    if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
 525    {
 526       /* Strip "#nnnn " from beginning of error message. */
 527       int offset;
 528       char error_number[16];
 529       for (offset = 0; offset<15; offset++)
 530       {
 531          error_number[offset] = error_message[offset + 1];
 532          if (error_message[offset] == ' ')
 533             break;
 534       }
 535
 536       if ((offset > 1) && (offset < 15))
 537       {
 538          error_number[offset - 1] = '\0';
 539          fprintf(stderr, "libpng error no. %s: %s",
 540              error_number, error_message + offset + 1);
 541          fprintf(stderr, PNG_STRING_NEWLINE);
 542       }
 543
 544       else
 545       {
 546          fprintf(stderr, "libpng error: %s, offset=%d",
 547              error_message, offset);
 548          fprintf(stderr, PNG_STRING_NEWLINE);
 549       }
 550    }
 551    else
 552 #endif
 553    {
 554       fprintf(stderr, "libpng error: %s", error_message ? error_message :
 555          "undefined");
 556       fprintf(stderr, PNG_STRING_NEWLINE);
 557    }
 558 #else
 559    PNG_UNUSED(error_message) /* Make compiler happy */
 560 #endif
 561    png_longjmp(png_ptr, 1);
 562 }
 563
 564 PNG_FUNCTION(void,PNGAPI
 565 png_longjmp,(png_structp png_ptr, int val),PNG_NORETURN)
 566 {
 567 #ifdef PNG_SETJMP_SUPPORTED
 568    if (png_ptr && png_ptr->longjmp_fn)
 569    {
 570 #  ifdef USE_FAR_KEYWORD
 571       {
 572          jmp_buf tmp_jmpbuf;
 573          png_memcpy(tmp_jmpbuf, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
 574          png_ptr->longjmp_fn(tmp_jmpbuf, val);
 575       }
 576
 577 #  else
 578    png_ptr->longjmp_fn(png_ptr->longjmp_buffer, val);
 579 #  endif
 580    }
 581 #endif
 582    /* Here if not setjmp support or if png_ptr is null. */
 583    PNG_ABORT();
 584 }
 585
 586 #ifdef PNG_WARNINGS_SUPPORTED
 587 /* This function is called when there is a warning, but the library thinks
 588  * it can continue anyway.  Replacement functions don't have to do anything
 589  * here if you don't want them to.  In the default configuration, png_ptr is
 590  * not used, but it is passed in case it may be useful.
 591  */
 592 static void /* PRIVATE */
 593 png_default_warning(png_structp png_ptr, png_const_charp warning_message)
 594 {
 595 #ifdef PNG_CONSOLE_IO_SUPPORTED
 596 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
 597    if (*warning_message == PNG_LITERAL_SHARP)
 598    {
 599       int offset;
 600       char warning_number[16];
 601       for (offset = 0; offset < 15; offset++)
 602       {
 603          warning_number[offset] = warning_message[offset + 1];
 604          if (warning_message[offset] == ' ')
 605             break;
 606       }
 607
 608       if ((offset > 1) && (offset < 15))
 609       {
 610          warning_number[offset + 1] = '\0';
 611          fprintf(stderr, "libpng warning no. %s: %s",
 612              warning_number, warning_message + offset);
 613          fprintf(stderr, PNG_STRING_NEWLINE);
 614       }
 615
 616       else
 617       {
 618          fprintf(stderr, "libpng warning: %s",
 619              warning_message);
 620          fprintf(stderr, PNG_STRING_NEWLINE);
 621       }
 622    }
 623    else
 624 #  endif
 625
 626    {
 627       fprintf(stderr, "libpng warning: %s", warning_message);
 628       fprintf(stderr, PNG_STRING_NEWLINE);
 629    }
 630 #else
 631    PNG_UNUSED(warning_message) /* Make compiler happy */
 632 #endif
 633    PNG_UNUSED(png_ptr) /* Make compiler happy */
 634 }
 635 #endif /* PNG_WARNINGS_SUPPORTED */
 636
 637 /* This function is called when the application wants to use another method
 638  * of handling errors and warnings.  Note that the error function MUST NOT
 639  * return to the calling routine or serious problems will occur.  The return
 640  * method used in the default routine calls longjmp(png_ptr->longjmp_buffer, 1)
 641  */
 642 void PNGAPI
 643 png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
 644     png_error_ptr error_fn, png_error_ptr warning_fn)
 645 {
 646    if (png_ptr == NULL)
 647       return;
 648
 649    png_ptr->error_ptr = error_ptr;
 650    png_ptr->error_fn = error_fn;
 651 #ifdef PNG_WARNINGS_SUPPORTED
 652    png_ptr->warning_fn = warning_fn;
 653 #else
 654    PNG_UNUSED(warning_fn)
 655 #endif
 656 }
 657
 658
 659 /* This function returns a pointer to the error_ptr associated with the user
 660  * functions.  The application should free any memory associated with this
 661  * pointer before png_write_destroy and png_read_destroy are called.
 662  */
 663 png_voidp PNGAPI
 664 png_get_error_ptr(png_const_structp png_ptr)
 665 {
 666    if (png_ptr == NULL)
 667       return NULL;
 668
 669    return ((png_voidp)png_ptr->error_ptr);
 670 }
 671
 672
 673 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 674 void PNGAPI
 675 png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
 676 {
 677    if (png_ptr != NULL)
 678    {
 679       png_ptr->flags &=
 680          ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
 681          PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
 682    }
 683 }
 684 #endif
 685 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */