Bug 609499 - Some invalid GIF files don't terminate their LZW data with a 0-length block. Handle them better by handling them less specially. r=jrmuizel

modules/libpr0n/decoders/nsGIFDecoder2.cpp

@@ -1027,27 +1027,14 @@ nsGIFDecoder2::WriteInternal(const char *aBuffer, PRUint32 aCount)
 
     case gif_sub_block:
       mGIFStruct.count = *q;
-      if (mGIFStruct.count) {
-        /* Still working on the same image: Process next LZW data block */
-        /* Make sure there are still rows left. If the GIF data */
-        /* is corrupt, we may not get an explicit terminator.   */
-        if (!mGIFStruct.rows_remaining) {
-#ifdef DONT_TOLERATE_BROKEN_GIFS
-          mGIFStruct.state = gif_error;
-          break;
-#else
-          /* This is an illegal GIF, but we remain tolerant. */
-          GETN(1, gif_sub_block);
-#endif
-          if (mGIFStruct.count == GIF_TRAILER) {
-            /* Found a terminator anyway, so consider the image done */
-            GETN(1, gif_done);
-            break;
-          }
-        }
+      // We can have multiple LZW data blocks. Process the next, but only if
+      // there are any rows left. (If the GIF is invalid, we might not get an
+      // explicit 0-size block terminator.)
+      if (mGIFStruct.count && mGIFStruct.rows_remaining) {
         GETN(mGIFStruct.count, gif_lzw);
       } else {
-        /* See if there are any more images in this sequence. */
+        // We've finished decoding this image. See if there are any more images
+        // in this sequence.
         EndImageFrame();
         GETN(1, gif_image_start);
       }