diff options
| -rw-r--r-- | libnsgif.c | 33 | ||||
| -rw-r--r-- | libnsgif.h | 3 |
2 files changed, 30 insertions, 6 deletions
@@ -574,9 +574,27 @@ static gif_result gif_initialise_frame(gif_animation *gif) { block_size = 0; while (block_size != 1) { block_size = gif_data[0] + 1; - if ((gif_bytes -= block_size) < 0) - return GIF_INSUFFICIENT_FRAME_DATA; - gif_data += block_size; + /* Check if the frame data runs off the end of the file + */ + if ((int)(gif_bytes - block_size) < 0) { + /* Try to recover by signaling the end of the gif. + * Once we get garbage data, there is no logical + * way to determine where the next frame is. + * It's probably better to partially load the gif + * than not at all. + */ + if (gif_bytes >= 2) { + gif_data[0] = 0; + gif_data[1] = GIF_TRAILER; + gif_bytes = 1; + ++gif_data; + break; + } else + return GIF_INSUFFICIENT_FRAME_DATA; + } else { + gif_bytes -= block_size; + gif_data += block_size; + } } /* Add the frame and set the display flag @@ -957,7 +975,12 @@ gif_result gif_decode_frame(gif_animation *gif, unsigned int frame) { } } else { if (!gif_next_LZW(gif)) { - return_value = gif->current_error; + /* Unexpected end of frame, try to recover + */ + if (gif->current_error == GIF_END_OF_FRAME) + return_value = GIF_OK; + else + return_value = gif->current_error; goto gif_decode_frame_exit; } } @@ -1190,7 +1213,7 @@ static int gif_next_code(gif_animation *gif, int code_size) { end = curbit + code_size; if (end >= lastbit) { if (get_done) - return GIF_INSUFFICIENT_FRAME_DATA; + return GIF_END_OF_FRAME; buf[0] = direct[last_byte - 2]; buf[1] = direct[last_byte - 1]; @@ -36,7 +36,8 @@ typedef enum { GIF_INSUFFICIENT_DATA = -3, GIF_DATA_ERROR = -4, GIF_INSUFFICIENT_MEMORY = -5, - GIF_FRAME_NO_DISPLAY = -6 + GIF_FRAME_NO_DISPLAY = -6, + GIF_END_OF_FRAME = -7 } gif_result; /* The GIF frame data |