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 /* pngerror.c - stub functions for i/o and memory allocation

  *

  * Last changed in libpng 1.6.10 [March 6, 2014]

  * Copyright (c) 1998-2014 Glenn Randers-Pehrson

  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

  *

  * This code is released under the libpng license.

  * For conditions of distribution and use, see the disclaimer

  * and license in png.h

  *

  * This file provides a location for all error handling.  Users who

  * need special error handling are expected to write replacement functions

  * and use png_set_error_fn() to use those functions.  See the instructions

  * at each function.

  */

 #include "pngpriv.h"

 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)

 static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,

     png_const_charp error_message)),PNG_NORETURN);

 #ifdef PNG_WARNINGS_SUPPORTED

 static void /* PRIVATE */

 png_default_warning PNGARG((png_const_structrp png_ptr,

    png_const_charp warning_message));

 #endif /* PNG_WARNINGS_SUPPORTED */

 /* This function is called whenever there is a fatal error.  This function

  * should not be changed.  If there is a need to handle errors differently,

  * you should supply a replacement error function and use png_set_error_fn()

  * to replace the error function at run-time.

  */

 #ifdef PNG_ERROR_TEXT_SUPPORTED

 PNG_FUNCTION(void,PNGAPI

 png_error,(png_const_structrp png_ptr, png_const_charp error_message),

    PNG_NORETURN)

 {

 #ifdef PNG_ERROR_NUMBERS_SUPPORTED

    char msg[16];

    if (png_ptr != NULL)

    {

       if (png_ptr->flags&

          (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))

       {

          if (*error_message == PNG_LITERAL_SHARP)

          {

             /* Strip "#nnnn " from beginning of error message. */

             int offset;

             for (offset = 1; offset<15; offset++)

                if (error_message[offset] == ' ')

                   break;

             if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)

             {

                int i;

                for (i = 0; i < offset - 1; i++)

                   msg[i] = error_message[i + 1];

                msg[i - 1] = '\0';

                error_message = msg;

             }

             else

                error_message += offset;

       }

       else

       {

          if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)

          {

             msg[0] = '0';

             msg[1] = '\0';

             error_message = msg;

          }

        }

      }

    }

 #endif

    if (png_ptr != NULL && png_ptr->error_fn != NULL)

       (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),

           error_message);

    /* If the custom handler doesn't exist, or if it returns,

       use the default handler, which will not return. */

    png_default_error(png_ptr, error_message);

 }

 #else

 PNG_FUNCTION(void,PNGAPI

 png_err,(png_const_structrp png_ptr),PNG_NORETURN)

 {

    /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed

     * erroneously as '\0', instead of the empty string "".  This was

     * apparently an error, introduced in libpng-1.2.20, and png_default_error

     * will crash in this case.

     */

    if (png_ptr != NULL && png_ptr->error_fn != NULL)

       (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");

    /* If the custom handler doesn't exist, or if it returns,

       use the default handler, which will not return. */

    png_default_error(png_ptr, "");

 }

 #endif /* PNG_ERROR_TEXT_SUPPORTED */

 /* Utility to safely appends strings to a buffer.  This never errors out so

  * error checking is not required in the caller.

  */

 size_t

 png_safecat(png_charp buffer, size_t bufsize, size_t pos,

    png_const_charp string)

 {

    if (buffer != NULL && pos < bufsize)

    {

       if (string != NULL)

          while (*string != '\0' && pos < bufsize-1)

            buffer[pos++] = *string++;

       buffer[pos] = '\0';

    }

    return pos;

 }

 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)

 /* Utility to dump an unsigned value into a buffer, given a start pointer and

  * and end pointer (which should point just *beyond* the end of the buffer!)

  * Returns the pointer to the start of the formatted string.

  */

 png_charp

 png_format_number(png_const_charp start, png_charp end, int format,

    png_alloc_size_t number)

 {

    int count = 0;    /* number of digits output */

    int mincount = 1; /* minimum number required */

    int output = 0;   /* digit output (for the fixed point format) */

    *--end = '\0';

    /* This is written so that the loop always runs at least once, even with

     * number zero.

     */

    while (end > start && (number != 0 || count < mincount))

    {

       static const char digits[] = "0123456789ABCDEF";

       switch (format)

       {

          case PNG_NUMBER_FORMAT_fixed:

             /* Needs five digits (the fraction) */

             mincount = 5;

             if (output || number % 10 != 0)

             {

                *--end = digits[number % 10];

                output = 1;

             }

             number /= 10;

             break;

          case PNG_NUMBER_FORMAT_02u:

             /* Expects at least 2 digits. */

             mincount = 2;

             /* FALL THROUGH */

          case PNG_NUMBER_FORMAT_u:

             *--end = digits[number % 10];

             number /= 10;

             break;

          case PNG_NUMBER_FORMAT_02x:

             /* This format expects at least two digits */

             mincount = 2;

             /* FALL THROUGH */

          case PNG_NUMBER_FORMAT_x:

             *--end = digits[number & 0xf];

             number >>= 4;

             break;

          default: /* an error */

             number = 0;

             break;

       }

       /* Keep track of the number of digits added */

       ++count;

       /* Float a fixed number here: */

       if (format == PNG_NUMBER_FORMAT_fixed) if (count == 5) if (end > start)

       {

          /* End of the fraction, but maybe nothing was output?  In that case

           * drop the decimal point.  If the number is a true zero handle that

           * here.

           */

          if (output)

             *--end = '.';

          else if (number == 0) /* and !output */

             *--end = '0';

       }

    }

    return end;

 }

 #endif

 #ifdef PNG_WARNINGS_SUPPORTED

 /* This function is called whenever there is a non-fatal error.  This function

  * should not be changed.  If there is a need to handle warnings differently,

  * you should supply a replacement warning function and use

  * png_set_error_fn() to replace the warning function at run-time.

  */

 void PNGAPI

 png_warning(png_const_structrp png_ptr, png_const_charp warning_message)

 {

    int offset = 0;

    if (png_ptr != NULL)

    {

 #ifdef PNG_ERROR_NUMBERS_SUPPORTED

    if (png_ptr->flags&

        (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))

 #endif

       {

          if (*warning_message == PNG_LITERAL_SHARP)

          {

             for (offset = 1; offset < 15; offset++)

                if (warning_message[offset] == ' ')

                   break;

          }

       }

    }

    if (png_ptr != NULL && png_ptr->warning_fn != NULL)

       (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),

          warning_message + offset);

    else

       png_default_warning(png_ptr, warning_message + offset);

 }

 /* These functions support 'formatted' warning messages with up to

  * PNG_WARNING_PARAMETER_COUNT parameters.  In the format string the parameter

  * is introduced by @<number>, where 'number' starts at 1.  This follows the

  * standard established by X/Open for internationalizable error messages.

  */

 void

 png_warning_parameter(png_warning_parameters p, int number,

    png_const_charp string)

 {

    if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)

       (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);

 }

 void

 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,

    png_alloc_size_t value)

 {

    char buffer[PNG_NUMBER_BUFFER_SIZE];

    png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));

 }

 void

 png_warning_parameter_signed(png_warning_parameters p, int number, int format,

    png_int_32 value)

 {

    png_alloc_size_t u;

    png_charp str;

    char buffer[PNG_NUMBER_BUFFER_SIZE];

    /* Avoid overflow by doing the negate in a png_alloc_size_t: */

    u = (png_alloc_size_t)value;

    if (value < 0)

       u = ~u + 1;

    str = PNG_FORMAT_NUMBER(buffer, format, u);

    if (value < 0 && str > buffer)

       *--str = '-';

    png_warning_parameter(p, number, str);

 }

 void

 png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,

    png_const_charp message)

 {

    /* The internal buffer is just 192 bytes - enough for all our messages,

     * overflow doesn't happen because this code checks!  If someone figures

     * out how to send us a message longer than 192 bytes, all that will

     * happen is that the message will be truncated appropriately.

     */

    size_t i = 0; /* Index in the msg[] buffer: */

    char msg[192];

    /* Each iteration through the following loop writes at most one character

     * to msg[i++] then returns here to validate that there is still space for

     * the trailing '\0'.  It may (in the case of a parameter) read more than

     * one character from message[]; it must check for '\0' and continue to the

     * test if it finds the end of string.

     */

    while (i<(sizeof msg)-1 && *message != '\0')

    {

       /* '@' at end of string is now just printed (previously it was skipped);

        * it is an error in the calling code to terminate the string with @.

        */

       if (p != NULL && *message == '@' && message[1] != '\0')

       {

          int parameter_char = *++message; /* Consume the '@' */

          static const char valid_parameters[] = "123456789";

          int parameter = 0;

          /* Search for the parameter digit, the index in the string is the

           * parameter to use.

           */

          while (valid_parameters[parameter] != parameter_char &&

             valid_parameters[parameter] != '\0')

             ++parameter;

          /* If the parameter digit is out of range it will just get printed. */

          if (parameter < PNG_WARNING_PARAMETER_COUNT)

          {

             /* Append this parameter */

             png_const_charp parm = p[parameter];

             png_const_charp pend = p[parameter] + (sizeof p[parameter]);

             /* No need to copy the trailing '\0' here, but there is no guarantee

              * that parm[] has been initialized, so there is no guarantee of a

              * trailing '\0':

              */

             while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)

                msg[i++] = *parm++;

             /* Consume the parameter digit too: */

             ++message;

             continue;

          }

          /* else not a parameter and there is a character after the @ sign; just

           * copy that.  This is known not to be '\0' because of the test above.

           */

       }

       /* At this point *message can't be '\0', even in the bad parameter case

        * above where there is a lone '@' at the end of the message string.

        */

       msg[i++] = *message++;

    }

    /* i is always less than (sizeof msg), so: */

    msg[i] = '\0';

    /* And this is the formatted message. It may be larger than

     * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these

     * are not (currently) formatted.

     */

    png_warning(png_ptr, msg);

 }

 #endif /* PNG_WARNINGS_SUPPORTED */

 #ifdef PNG_BENIGN_ERRORS_SUPPORTED

 void PNGAPI

 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)

 {

    if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)

    {

 #     ifdef PNG_READ_SUPPORTED

          if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&

             png_ptr->chunk_name != 0)

             png_chunk_warning(png_ptr, error_message);

          else

 #     endif

       png_warning(png_ptr, error_message);

    }

    else

    {

 #     ifdef PNG_READ_SUPPORTED

          if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&

             png_ptr->chunk_name != 0)

             png_chunk_error(png_ptr, error_message);

          else

 #     endif

       png_error(png_ptr, error_message);

    }

 #  ifndef PNG_ERROR_TEXT_SUPPORTED

       PNG_UNUSED(error_message)

 #  endif

 }

 void /* PRIVATE */

 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)

 {

   if (png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN)

      png_warning(png_ptr, error_message);

   else

      png_error(png_ptr, error_message);

 #  ifndef PNG_ERROR_TEXT_SUPPORTED

       PNG_UNUSED(error_message)

 #  endif

 }

 void /* PRIVATE */

 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)

 {

   if (png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN)

      png_warning(png_ptr, error_message);

   else

      png_error(png_ptr, error_message);

 #  ifndef PNG_ERROR_TEXT_SUPPORTED

       PNG_UNUSED(error_message)

 #  endif

 }

 #endif /* BENIGN_ERRORS */

 /* These utilities are used internally to build an error message that relates

  * to the current chunk.  The chunk name comes from png_ptr->chunk_name,

  * this is used to prefix the message.  The message is limited in length

  * to 63 bytes, the name characters are output as hex digits wrapped in []

  * if the character is invalid.

  */

 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))

 static PNG_CONST char png_digit[16] = {

    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',

    'A', 'B', 'C', 'D', 'E', 'F'

 };

 #define PNG_MAX_ERROR_TEXT 196 /* Currently limited be profile_error in png.c */

 #if defined(PNG_WARNINGS_SUPPORTED) || \

    (defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))

 static void /* PRIVATE */

 png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp

     error_message)

 {

    png_uint_32 chunk_name = png_ptr->chunk_name;

    int iout = 0, ishift = 24;

    while (ishift >= 0)

    {

       int c = (int)(chunk_name >> ishift) & 0xff;

       ishift -= 8;

       if (isnonalpha(c))

       {

          buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;

          buffer[iout++] = png_digit[(c & 0xf0) >> 4];

          buffer[iout++] = png_digit[c & 0x0f];

          buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;

       }

       else

       {

          buffer[iout++] = (char)c;

       }

    }

    if (error_message == NULL)

       buffer[iout] = '\0';

    else

    {

       int iin = 0;

       buffer[iout++] = ':';

       buffer[iout++] = ' ';

       while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')

          buffer[iout++] = error_message[iin++];

       /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */

       buffer[iout] = '\0';

    }

 }

 #endif /* PNG_WARNINGS_SUPPORTED || PNG_ERROR_TEXT_SUPPORTED */

 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)

 PNG_FUNCTION(void,PNGAPI

 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),

    PNG_NORETURN)

 {

    char msg[18+PNG_MAX_ERROR_TEXT];

    if (png_ptr == NULL)

       png_error(png_ptr, error_message);

    else

    {

       png_format_buffer(png_ptr, msg, error_message);

       png_error(png_ptr, msg);

    }

 }

 #endif /* PNG_READ_SUPPORTED && PNG_ERROR_TEXT_SUPPORTED */

 #ifdef PNG_WARNINGS_SUPPORTED

 void PNGAPI

 png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)

 {

    char msg[18+PNG_MAX_ERROR_TEXT];

    if (png_ptr == NULL)

       png_warning(png_ptr, warning_message);

    else

    {

       png_format_buffer(png_ptr, msg, warning_message);

       png_warning(png_ptr, msg);

    }

 }

 #endif /* PNG_WARNINGS_SUPPORTED */

 #ifdef PNG_READ_SUPPORTED

 #ifdef PNG_BENIGN_ERRORS_SUPPORTED

 void PNGAPI

 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp

     error_message)

 {

    if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)

       png_chunk_warning(png_ptr, error_message);

    else

       png_chunk_error(png_ptr, error_message);

 #  ifndef PNG_ERROR_TEXT_SUPPORTED

       PNG_UNUSED(error_message)

 #  endif

 }

 #endif

 #endif /* PNG_READ_SUPPORTED */

 void /* PRIVATE */

 png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)

 {

 #  ifndef PNG_WARNINGS_SUPPORTED

       PNG_UNUSED(message)

 #  endif

    /* This is always supported, but for just read or just write it

     * unconditionally does the right thing.

     */

 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)

       if (png_ptr->mode & PNG_IS_READ_STRUCT)

 #  endif

 #  ifdef PNG_READ_SUPPORTED

       {

          if (error < PNG_CHUNK_ERROR)

             png_chunk_warning(png_ptr, message);

          else

             png_chunk_benign_error(png_ptr, message);

       }

 #  endif

 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)

       else if (!(png_ptr->mode & PNG_IS_READ_STRUCT))

 #  endif

 #  ifdef PNG_WRITE_SUPPORTED

       {

          if (error < PNG_CHUNK_WRITE_ERROR)

             png_app_warning(png_ptr, message);

          else

             png_app_error(png_ptr, message);

       }

 #  endif

 }

 #ifdef PNG_ERROR_TEXT_SUPPORTED

 #ifdef PNG_FLOATING_POINT_SUPPORTED

 PNG_FUNCTION(void,

 png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)

 {

 #  define fixed_message "fixed point overflow in "

 #  define fixed_message_ln ((sizeof fixed_message)-1)

    int  iin;

    char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];

    memcpy(msg, fixed_message, fixed_message_ln);

    iin = 0;

    if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)

    {

       msg[fixed_message_ln + iin] = name[iin];

       ++iin;

    }

    msg[fixed_message_ln + iin] = 0;

    png_error(png_ptr, msg);

 }

 #endif

 #endif

 #ifdef PNG_SETJMP_SUPPORTED

 /* This API only exists if ANSI-C style error handling is used,

  * otherwise it is necessary for png_default_error to be overridden.

  */

 jmp_buf* PNGAPI

 png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,

     size_t jmp_buf_size)

 {

    /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value

     * and it must not change after that.  Libpng doesn't care how big the

     * buffer is, just that it doesn't change.

     *

     * If the buffer size is no *larger* than the size of jmp_buf when libpng is

     * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0

     * semantics that this call will not fail.  If the size is larger, however,

     * the buffer is allocated and this may fail, causing the function to return

     * NULL.

     */

    if (png_ptr == NULL)

       return NULL;

    if (png_ptr->jmp_buf_ptr == NULL)

    {

       png_ptr->jmp_buf_size = 0; /* not allocated */

       if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))

          png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;

       else

       {

          png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,

             png_malloc_warn(png_ptr, jmp_buf_size));

          if (png_ptr->jmp_buf_ptr == NULL)

             return NULL; /* new NULL return on OOM */

          png_ptr->jmp_buf_size = jmp_buf_size;

       }

    }

    else /* Already allocated: check the size */

    {

       size_t size = png_ptr->jmp_buf_size;

       if (size == 0)

       {

          size = (sizeof png_ptr->jmp_buf_local);

          if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)

          {

             /* This is an internal error in libpng: somehow we have been left

              * with a stack allocated jmp_buf when the application regained

              * control.  It's always possible to fix this up, but for the moment

              * this is a png_error because that makes it easy to detect.

              */

             png_error(png_ptr, "Libpng jmp_buf still allocated");

             /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */

          }

       }

       if (size != jmp_buf_size)

       {

          png_warning(png_ptr, "Application jmp_buf size changed");

          return NULL; /* caller will probably crash: no choice here */

       }

    }

    /* Finally fill in the function, now we have a satisfactory buffer. It is

     * valid to change the function on every call.

     */

    png_ptr->longjmp_fn = longjmp_fn;

    return png_ptr->jmp_buf_ptr;

 }

 void /* PRIVATE */

 png_free_jmpbuf(png_structrp png_ptr)

 {

    if (png_ptr != NULL)

    {

       jmp_buf *jb = png_ptr->jmp_buf_ptr;

       /* A size of 0 is used to indicate a local, stack, allocation of the

        * pointer; used here and in png.c

        */

       if (jb != NULL && png_ptr->jmp_buf_size > 0)

       {

          /* This stuff is so that a failure to free the error control structure

           * does not leave libpng in a state with no valid error handling: the

           * free always succeeds, if there is an error it gets ignored.

           */

          if (jb != &png_ptr->jmp_buf_local)

          {

             /* Make an internal, libpng, jmp_buf to return here */

             jmp_buf free_jmp_buf;

             if (!setjmp(free_jmp_buf))

             {

                png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */

                png_ptr->jmp_buf_size = 0; /* stack allocation */

                png_ptr->longjmp_fn = longjmp;

                png_free(png_ptr, jb); /* Return to setjmp on error */

             }

          }

       }

       /* *Always* cancel everything out: */

       png_ptr->jmp_buf_size = 0;

       png_ptr->jmp_buf_ptr = NULL;

       png_ptr->longjmp_fn = 0;

    }

 }

 #endif

 /* This is the default error handling function.  Note that replacements for

  * this function MUST NOT RETURN, or the program will likely crash.  This

  * function is used by default, or if the program supplies NULL for the

  * error function pointer in png_set_error_fn().

  */

 static PNG_FUNCTION(void /* PRIVATE */,

 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),

    PNG_NORETURN)

 {

 #ifdef PNG_CONSOLE_IO_SUPPORTED

 #ifdef PNG_ERROR_NUMBERS_SUPPORTED

    /* Check on NULL only added in 1.5.4 */

    if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)

    {

       /* Strip "#nnnn " from beginning of error message. */

       int offset;

       char error_number[16];

       for (offset = 0; offset<15; offset++)

       {

          error_number[offset] = error_message[offset + 1];

          if (error_message[offset] == ' ')

             break;

       }

       if ((offset > 1) && (offset < 15))

       {

          error_number[offset - 1] = '\0';

          fprintf(stderr, "libpng error no. %s: %s",

              error_number, error_message + offset + 1);

          fprintf(stderr, PNG_STRING_NEWLINE);

       }

       else

       {

          fprintf(stderr, "libpng error: %s, offset=%d",

              error_message, offset);

          fprintf(stderr, PNG_STRING_NEWLINE);

       }

    }

    else

 #endif

    {

       fprintf(stderr, "libpng error: %s", error_message ? error_message :

          "undefined");

       fprintf(stderr, PNG_STRING_NEWLINE);

    }

 #else

    PNG_UNUSED(error_message) /* Make compiler happy */

 #endif

    png_longjmp(png_ptr, 1);

 }

 PNG_FUNCTION(void,PNGAPI

 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)

 {

 #ifdef PNG_SETJMP_SUPPORTED

    if (png_ptr && png_ptr->longjmp_fn && png_ptr->jmp_buf_ptr)

       png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);

 #endif

    /* If control reaches this point, png_longjmp() must not return. The only

     * choice is to terminate the whole process (or maybe the thread); to do

     * this the ANSI-C abort() function is used unless a different method is 

     * implemented by overriding the default configuration setting for

     * PNG_ABORT().

     */

    PNG_ABORT();

 }

 #ifdef PNG_WARNINGS_SUPPORTED

 /* This function is called when there is a warning, but the library thinks

  * it can continue anyway.  Replacement functions don't have to do anything

  * here if you don't want them to.  In the default configuration, png_ptr is

  * not used, but it is passed in case it may be useful.

  */

 static void /* PRIVATE */

 png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)

 {

 #ifdef PNG_CONSOLE_IO_SUPPORTED

 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED

    if (*warning_message == PNG_LITERAL_SHARP)

    {

       int offset;

       char warning_number[16];

       for (offset = 0; offset < 15; offset++)

       {

          warning_number[offset] = warning_message[offset + 1];

          if (warning_message[offset] == ' ')

             break;

       }

       if ((offset > 1) && (offset < 15))

       {

          warning_number[offset + 1] = '\0';

          fprintf(stderr, "libpng warning no. %s: %s",

              warning_number, warning_message + offset);

          fprintf(stderr, PNG_STRING_NEWLINE);

       }

       else

       {

          fprintf(stderr, "libpng warning: %s",

              warning_message);

          fprintf(stderr, PNG_STRING_NEWLINE);

       }

    }

    else

 #  endif

    {

       fprintf(stderr, "libpng warning: %s", warning_message);

       fprintf(stderr, PNG_STRING_NEWLINE);

    }

 #else

    PNG_UNUSED(warning_message) /* Make compiler happy */

 #endif

    PNG_UNUSED(png_ptr) /* Make compiler happy */

 }

 #endif /* PNG_WARNINGS_SUPPORTED */

 /* This function is called when the application wants to use another method

  * of handling errors and warnings.  Note that the error function MUST NOT

  * return to the calling routine or serious problems will occur.  The return

  * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)

  */

 void PNGAPI

 png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,

     png_error_ptr error_fn, png_error_ptr warning_fn)

 {

    if (png_ptr == NULL)

       return;

    png_ptr->error_ptr = error_ptr;

    png_ptr->error_fn = error_fn;

 #ifdef PNG_WARNINGS_SUPPORTED

    png_ptr->warning_fn = warning_fn;

 #else

    PNG_UNUSED(warning_fn)

 #endif

 }

 /* This function returns a pointer to the error_ptr associated with the user

  * functions.  The application should free any memory associated with this

  * pointer before png_write_destroy and png_read_destroy are called.

  */

 png_voidp PNGAPI

 png_get_error_ptr(png_const_structrp png_ptr)

 {

    if (png_ptr == NULL)

       return NULL;

    return ((png_voidp)png_ptr->error_ptr);

 }

 #ifdef PNG_ERROR_NUMBERS_SUPPORTED

 void PNGAPI

 png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)

 {

    if (png_ptr != NULL)

    {

       png_ptr->flags &=

          ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |

          PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);

    }

 }

 #endif

 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\

    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)

    /* Currently the above both depend on SETJMP_SUPPORTED, however it would be

     * possible to implement without setjmp support just so long as there is some

     * way to handle the error return here:

     */

 PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI

 png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),

    PNG_NORETURN)

 {

    const png_const_structrp png_ptr = png_nonconst_ptr;

    png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);

    /* An error is always logged here, overwriting anything (typically a warning)

     * that is already there:

     */

    if (image != NULL)

    {

       png_safecat(image->message, (sizeof image->message), 0, error_message);

       image->warning_or_error |= PNG_IMAGE_ERROR;

       /* Retrieve the jmp_buf from within the png_control, making this work for

        * C++ compilation too is pretty tricky: C++ wants a pointer to the first

        * element of a jmp_buf, but C doesn't tell us the type of that.

        */

       if (image->opaque != NULL && image->opaque->error_buf != NULL)

          longjmp(png_control_jmp_buf(image->opaque), 1);

       /* Missing longjmp buffer, the following is to help debugging: */

       {

          size_t pos = png_safecat(image->message, (sizeof image->message), 0,

             "bad longjmp: ");

          png_safecat(image->message, (sizeof image->message), pos,

              error_message);

       }

    }

    /* Here on an internal programming error. */

    abort();

 }

 #ifdef PNG_WARNINGS_SUPPORTED

 void /* PRIVATE */ PNGCBAPI

 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)

 {

    const png_const_structrp png_ptr = png_nonconst_ptr;

    png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);

    /* A warning is only logged if there is no prior warning or error. */

    if (image->warning_or_error == 0)

    {

       png_safecat(image->message, (sizeof image->message), 0, warning_message);

       image->warning_or_error |= PNG_IMAGE_WARNING;

    }

 }

 #endif

 int /* PRIVATE */

 png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)

 {

    volatile png_imagep image = image_in;

    volatile int result;

    volatile png_voidp saved_error_buf;

    jmp_buf safe_jmpbuf;

    /* Safely execute function(arg) with png_error returning to this function. */

    saved_error_buf = image->opaque->error_buf;

    result = setjmp(safe_jmpbuf) == 0;

    if (result)

    {

       image->opaque->error_buf = safe_jmpbuf;

       result = function(arg);

    }

    image->opaque->error_buf = saved_error_buf;

    /* And do the cleanup prior to any failure return. */

    if (!result)

       png_image_free(image);

    return result;

 }

 #endif /* SIMPLIFIED READ/WRITE */

 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */