shithub: jbig2

Bug 702335: jbig2dec: Refill input buffer upon failure to parse segment header. Before commit 2b2dcf4ccf401ed210f03c858b304994749fd2b3 there was a debug message when attempting to parse a a segment header and the data supplied to jbig2dec was not enough. Commit 2b2dcf4 incorrectly changed the debug message into a fatal error message, due misinterpreting the message text as something that warranted a fatal error. When data was supplied in chunks to jbig2_data_in() in repeated calls such that a segment header's referred-to segment numbers field straddled a chunk boundary then jbig2dec would indicate a fatal error. The file in bug 702335 caused this to happen. Instead jbig2dec should be asking the caller for more data so that the entire segment header can be parsed during a single call to jbig2_data_in(). By convering the fatal error back to a a debug message the problem is resolved. The message itself is also rewored to clearly indicate that the situation is non-fatal and that the caller will be asked to provide more data.

--- a/jbig2_segment.c

+++ b/jbig2_segment.c

@@ -88,7 +88,7 @@

     referred_to_segment_size = result->number <= 256 ? 1 : result->number <= 65536 ? 2 : 4;     /* 7.2.5 */

     pa_size = result->flags & 0x40 ? 4 : 1;     /* 7.2.6 */

     if (offset + referred_to_segment_count * referred_to_segment_size + pa_size + 4 > buf_size) {

-        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, result->number, "insufficient data to parse segment header");

+        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, result->number, "attempted to parse segment header with insufficient data, asking for more data");

         jbig2_free(ctx->allocator, result);

         return NULL;