X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/2b5f62a0b2db198609b45dec622a018dae37008e..06a32e049c1bad9249079ad2e91659303424a774:/src/png/pngerror.c

diff --git a/src/png/pngerror.c b/src/png/pngerror.c
index 38938a66d8..7604bddf18 100644
--- a/src/png/pngerror.c
+++ b/src/png/pngerror.c
@@ -1,76 +1,210 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * libpng 1.2.5rc3 - September 18, 2002
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.7 [December 15, 2011]
+ * Copyright (c) 1998-2011 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.
  */
 
-#define PNG_INTERNAL
-#include "png.h"
+#include "pngpriv.h"
 
-static void /* PRIVATE */
-png_default_error PNGARG((png_structp png_ptr,
-  png_const_charp error_message));
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+
+static PNG_FUNCTION(void, png_default_error,PNGARG((png_structp png_ptr,
+    png_const_charp error_message)),PNG_NORETURN);
+
+#ifdef PNG_WARNINGS_SUPPORTED
 static void /* PRIVATE */
 png_default_warning PNGARG((png_structp png_ptr,
-  png_const_charp warning_message));
+   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.
  */
-void PNGAPI
-png_error(png_structp png_ptr, png_const_charp error_message)
+#ifdef PNG_ERROR_TEXT_SUPPORTED
+PNG_FUNCTION(void,PNGAPI
+png_error,(png_structp png_ptr, png_const_charp error_message),PNG_NORETURN)
 {
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
    char msg[16];
-   if (png_ptr->flags&(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+   if (png_ptr != NULL)
    {
-     int offset = 0;
-     if (*error_message == '#')
-     {
-         for (offset=1; offset<15; offset++)
-            if (*(error_message+offset) == ' ')
-                break;
-         if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+      if (png_ptr->flags&
+         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+      {
+         if (*error_message == PNG_LITERAL_SHARP)
          {
-            int i;
-            for (i=0; i<offset-1; i++)
-               msg[i]=error_message[i+1];
-            msg[i]='\0';
-            error_message=msg;
-         }
-         else
-            error_message+=offset;
-     }
-     else
-     {
+            /* 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;
+            msg[0] = '0';
+            msg[1] = '\0';
+            error_message = msg;
          }
+       }
      }
    }
 #endif
-   if (png_ptr->error_fn != NULL)
+   if (png_ptr != NULL && png_ptr->error_fn != NULL)
       (*(png_ptr->error_fn))(png_ptr, error_message);
 
-   /* if the following returns or doesn't exist, use the default function,
-      which will not return */
+   /* 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_structp 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_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
@@ -79,24 +213,148 @@ png_error(png_structp png_ptr, png_const_charp error_message)
 void PNGAPI
 png_warning(png_structp png_ptr, png_const_charp warning_message)
 {
-     int offset = 0;
+   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))
+   if (png_ptr->flags&
+       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
 #endif
-   {
-     if (*warning_message == '#')
-     {
-         for (offset=1; offset<15; offset++)
-            if (*(warning_message+offset) == ' ')
-                break;
-     }
+      {
+         if (*warning_message == PNG_LITERAL_SHARP)
+         {
+            for (offset = 1; offset < 15; offset++)
+               if (warning_message[offset] == ' ')
+                  break;
+         }
+      }
    }
-   if (png_ptr->warning_fn != NULL)
-      (*(png_ptr->warning_fn))(png_ptr,
-         (png_const_charp)(warning_message+offset));
+   if (png_ptr != NULL && png_ptr->warning_fn != NULL)
+      (*(png_ptr->warning_fn))(png_ptr, warning_message + offset);
    else
-      png_default_warning(png_ptr, (png_const_charp)(warning_message+offset));
+      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_structp png_ptr, png_warning_parameters p,
+   png_const_charp message)
+{
+   /* The internal buffer is just 128 bytes - enough for all our messages,
+    * overflow doesn't happen because this code checks!
+    */
+   size_t i;
+   char msg[128];
+
+   for (i=0; i<(sizeof msg)-1 && *message != '\0'; ++i)
+   {
+      if (*message == '@')
+      {
+         int parameter = -1;
+         switch (*++message)
+         {
+            case '1':
+               parameter = 0;
+               break;
+
+            case '2':
+               parameter = 1;
+               break;
+
+            case '\0':
+               continue; /* To break out of the for loop above. */
+
+            default:
+               break;
+         }
+
+         if (parameter >= 0 && 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':
+             */
+            for (; i<(sizeof msg)-1 && parm != '\0' && parm < pend; ++i)
+               msg[i] = *parm++;
+
+            ++message;
+            continue;
+         }
+
+         /* else not a parameter and there is a character after the @ sign; just
+          * copy that.
+          */
+      }
+
+      /* 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: */
+   png_warning(png_ptr, msg);
+}
+#endif /* PNG_WARNINGS_SUPPORTED */
+
+#ifdef PNG_BENIGN_ERRORS_SUPPORTED
+void PNGAPI
+png_benign_error(png_structp png_ptr, png_const_charp error_message)
+{
+  if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+     png_warning(png_ptr, error_message);
+  else
+     png_error(png_ptr, error_message);
 }
+#endif
 
 /* 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,
@@ -104,114 +362,219 @@ png_warning(png_structp png_ptr, png_const_charp warning_message)
  * to 63 bytes, the name characters are output as hex digits wrapped in []
  * if the character is invalid.
  */
-#define isnonalpha(c) ((c) < 41 || (c) > 122 || ((c) > 90 && (c) < 97))
+#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' };
+   '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+   'A', 'B', 'C', 'D', 'E', 'F'
+};
 
+#define PNG_MAX_ERROR_TEXT 64
+#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
 static void /* PRIVATE */
 png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp
-   error_message)
+    error_message)
 {
-   int iout = 0, iin = 0;
+   png_uint_32 chunk_name = png_ptr->chunk_name;
+   int iout = 0, ishift = 24;
 
-   while (iin < 4)
+   while (ishift >= 0)
    {
-      int c = png_ptr->chunk_name[iin++];
+      int c = (int)(chunk_name >> ishift) & 0xff;
+
+      ishift -= 8;
       if (isnonalpha(c))
       {
-         buffer[iout++] = '[';
+         buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
          buffer[iout++] = png_digit[(c & 0xf0) >> 4];
          buffer[iout++] = png_digit[c & 0x0f];
-         buffer[iout++] = ']';
+         buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
       }
+
       else
       {
-         buffer[iout++] = (png_byte)c;
+         buffer[iout++] = (char)c;
       }
    }
 
    if (error_message == NULL)
-      buffer[iout] = 0;
+      buffer[iout] = '\0';
+
    else
    {
+      int iin = 0;
+
       buffer[iout++] = ':';
       buffer[iout++] = ' ';
-      png_memcpy(buffer+iout, error_message, 64);
-      buffer[iout+63] = 0;
+
+      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 */
 
-void PNGAPI
-png_chunk_error(png_structp png_ptr, png_const_charp error_message)
+#if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
+PNG_FUNCTION(void,PNGAPI
+png_chunk_error,(png_structp png_ptr, png_const_charp error_message),
+   PNG_NORETURN)
 {
-   char msg[18+64];
-   png_format_buffer(png_ptr, msg, error_message);
-   png_error(png_ptr, msg);
+   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_structp png_ptr, png_const_charp warning_message)
 {
-   char msg[18+64];
-   png_format_buffer(png_ptr, msg, warning_message);
-   png_warning(png_ptr, msg);
+   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_structp 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);
+}
+#endif
+#endif /* PNG_READ_SUPPORTED */
+
+#ifdef PNG_ERROR_TEXT_SUPPORTED
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+PNG_FUNCTION(void,
+png_fixed_error,(png_structp 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];
+   png_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_structp png_ptr, png_longjmp_ptr longjmp_fn,
+    size_t jmp_buf_size)
+{
+   if (png_ptr == NULL || jmp_buf_size != png_sizeof(jmp_buf))
+      return NULL;
+
+   png_ptr->longjmp_fn = longjmp_fn;
+   return &png_ptr->longjmp_buffer;
 }
+#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 void /* PRIVATE */
-png_default_error(png_structp png_ptr, png_const_charp error_message)
+static PNG_FUNCTION(void /* PRIVATE */,
+png_default_error,(png_structp png_ptr, png_const_charp error_message),
+   PNG_NORETURN)
 {
-#ifndef PNG_NO_CONSOLE_IO
+#ifdef PNG_CONSOLE_IO_SUPPORTED
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-   if (*error_message == '#')
+   /* Check on NULL only added in 1.5.4 */
+   if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
    {
-     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\n", error_number,
-          error_message+offset);
-     }
-     else
-       fprintf(stderr, "libpng error: %s, offset=%d\n", error_message,offset);
+      /* 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\n", error_message);
+   {
+      fprintf(stderr, "libpng error: %s", error_message ? error_message :
+         "undefined");
+      fprintf(stderr, PNG_STRING_NEWLINE);
+   }
 #else
-   if (error_message)
-     /* make compiler happy */ ;
+   PNG_UNUSED(error_message) /* Make compiler happy */
 #endif
+   png_longjmp(png_ptr, 1);
+}
 
+PNG_FUNCTION(void,PNGAPI
+png_longjmp,(png_structp png_ptr, int val),PNG_NORETURN)
+{
 #ifdef PNG_SETJMP_SUPPORTED
-#  ifdef USE_FAR_KEYWORD
+   if (png_ptr && png_ptr->longjmp_fn)
    {
-      jmp_buf jmpbuf;
-      png_memcpy(jmpbuf,png_ptr->jmpbuf,sizeof(jmp_buf));
-      longjmp(jmpbuf, 1);
-   }
+#  ifdef USE_FAR_KEYWORD
+      {
+         jmp_buf tmp_jmpbuf;
+         png_memcpy(tmp_jmpbuf, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
+         png_ptr->longjmp_fn(tmp_jmpbuf, val);
+      }
+
 #  else
-   longjmp(png_ptr->jmpbuf, 1);
-# endif
-#else
-   if (png_ptr)
-     /* make compiler happy */ ;
-   PNG_ABORT();
+   png_ptr->longjmp_fn(png_ptr->longjmp_buffer, val);
+#  endif
+   }
 #endif
+   /* Here if not setjmp support or if png_ptr is null. */
+   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
@@ -220,50 +583,67 @@ png_default_error(png_structp png_ptr, png_const_charp error_message)
 static void /* PRIVATE */
 png_default_warning(png_structp png_ptr, png_const_charp warning_message)
 {
-#ifndef PNG_NO_CONSOLE_IO
+#ifdef PNG_CONSOLE_IO_SUPPORTED
 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
-   if (*warning_message == '#')
+   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) == ' ')
+      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\n", warning_number,
-          warning_message+offset);
-     }
-     else
-       fprintf(stderr, "libpng warning: %s\n", warning_message);
+      }
+
+      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\n", warning_message);
+
+   {
+      fprintf(stderr, "libpng warning: %s", warning_message);
+      fprintf(stderr, PNG_STRING_NEWLINE);
+   }
 #else
-   if (warning_message)
-     /* appease compiler */ ;
+   PNG_UNUSED(warning_message) /* Make compiler happy */
 #endif
-   if (png_ptr)
-      return;
+   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->jmpbuf, 1)
+ * method used in the default routine calls longjmp(png_ptr->longjmp_buffer, 1)
  */
 void PNGAPI
 png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
-   png_error_ptr error_fn, png_error_ptr warning_fn)
+    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
 }
 
 
@@ -272,8 +652,11 @@ png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
  * pointer before png_write_destroy and png_read_destroy are called.
  */
 png_voidp PNGAPI
-png_get_error_ptr(png_structp png_ptr)
+png_get_error_ptr(png_const_structp png_ptr)
 {
+   if (png_ptr == NULL)
+      return NULL;
+
    return ((png_voidp)png_ptr->error_ptr);
 }
 
@@ -282,10 +665,12 @@ png_get_error_ptr(png_structp png_ptr)
 void PNGAPI
 png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
 {
-   if(png_ptr != NULL)
+   if (png_ptr != NULL)
    {
-     png_ptr->flags &=
-       ((~(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
+      png_ptr->flags &=
+         ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
+         PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
    }
 }
 #endif
+#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */