Imported from libpng-0.97a.tar
diff --git a/pngerror.c b/pngerror.c
index a800884..77232d7 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -51,6 +51,60 @@
png_default_warning(png_ptr, message);
}
+/* These utilities are used internally to build an error message which 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) < 41 || (c) > 122 || ((c) > 90 && (c) < 97))
+static const char png_digit[16] = {
+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
+};
+
+static void
+png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp message)
+{
+ int iout = 0, iin = 0;
+
+ while (iin < 4) {
+ int c = png_ptr->chunk_name[iin++];
+ if (isnonalpha(c)) {
+ buffer[iout++] = '[';
+ buffer[iout++] = png_digit[(c & 0xf0) >> 4];
+ buffer[iout++] = png_digit[c & 0xf];
+ buffer[iout++] = ']';
+ } else {
+ buffer[iout++] = c;
+ }
+ }
+
+ if (message == NULL)
+ buffer[iout++] = 0;
+ else {
+ buffer[iout++] = ':';
+ buffer[iout++] = ' ';
+ strncpy(buffer+iout, message, 64);
+ buffer[iout+63] = 0;
+ }
+}
+
+void
+png_chunk_error(png_structp png_ptr, png_const_charp message)
+{
+ char msg[16+64];
+ png_format_buffer(png_ptr, msg, message);
+ png_error(png_ptr, msg);
+}
+
+void
+png_chunk_warning(png_structp png_ptr, png_const_charp message)
+{
+ char msg[16+64];
+ png_format_buffer(png_ptr, msg, message);
+ png_warning(png_ptr, msg);
+}
+
/* 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
