- if (ret != Z_STREAM_END)
- {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
- char umsg[52];
-
- if (ret == Z_BUF_ERROR)
- png_snprintf(umsg, 52,
- "Buffer error in compressed datastream in %s chunk",
- png_ptr->chunk_name);
- else if (ret == Z_DATA_ERROR)
- png_snprintf(umsg, 52,
- "Data error in compressed datastream in %s chunk",
- png_ptr->chunk_name);
- else
- png_snprintf(umsg, 52,
- "Incomplete compressed datastream in %s chunk",
- png_ptr->chunk_name);
- png_warning(png_ptr, umsg);
+
+ /* 0 means an error - notice that this code simple ignores
+ * zero length compressed chunks as a result.
+ */
+ return 0;
+ }
+}
+
+/*
+ * Decompress trailing data in a chunk. The assumption is that chunkdata
+ * points at an allocated area holding the contents of a chunk with a
+ * trailing compressed part. What we get back is an allocated area
+ * holding the original prefix part and an uncompressed version of the
+ * trailing part (the malloc area passed in is freed).
+ */
+void /* PRIVATE */
+png_decompress_chunk(png_structp png_ptr, int comp_type,
+ png_size_t chunklength,
+ png_size_t prefix_size, png_size_t *newlength)
+{
+ /* The caller should guarantee this */
+ if (prefix_size > chunklength)
+ {
+ /* The recovery is to delete the chunk. */
+ png_warning(png_ptr, "invalid chunklength");
+ prefix_size = 0; /* To delete everything */
+ }
+
+ else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+ {
+ png_size_t expanded_size = png_inflate(png_ptr,
+ (png_bytep)(png_ptr->chunkdata + prefix_size),
+ chunklength - prefix_size,
+ 0/*output*/, 0/*output size*/);
+
+ /* Now check the limits on this chunk - if the limit fails the
+ * compressed data will be removed, the prefix will remain.
+ */
+#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+ if (png_ptr->user_chunk_malloc_max &&
+ (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))