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  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 */
  933.