+#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 != 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_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_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)