[FFmpeg-devel] [PATCH 3/4] avcodec/mpegutils: consolidate single byte av_log()

[Michael Niedermayer]

Fixes: Timeout (56sec -> 15sec)
Fixes: 37141/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-6192122867875840

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/mpegutils.c | 56 ++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 24 deletions(-)

diff --git a/libavcodec/mpegutils.c b/libavcodec/mpegutils.c
index e5105ecc58..e91c554781 100644
--- a/libavcodec/mpegutils.c
+++ b/libavcodec/mpegutils.c
@@ -187,7 +187,6 @@ void ff_print_debug_info2(AVCodecContext *avctx, AVFrame *pict, uint8_t *mbskip_
 
         av_freep(&mvs);
     }
-
     /* TODO: export all the following to make them accessible for users (and filters) */
     if (avctx->hwaccel || !mbtype_table)
         return;
@@ -195,71 +194,80 @@ void ff_print_debug_info2(AVCodecContext *avctx, AVFrame *pict, uint8_t *mbskip_
 
     if (avctx->debug & (FF_DEBUG_SKIP | FF_DEBUG_QP | FF_DEBUG_MB_TYPE)) {
         int x,y;
+#define MB_STRING_SIZE 6
+        char *mbstring = av_malloc(MB_STRING_SIZE * mb_width + 1);
+        if (!mbstring)
+            return;
 
         av_log(avctx, AV_LOG_DEBUG, "New frame, type: %c\n",
                av_get_picture_type_char(pict->pict_type));
         for (y = 0; y < mb_height; y++) {
+            char *mbs = mbstring;
             for (x = 0; x < mb_width; x++) {
+                av_assert0(mbs - mbstring <= MB_STRING_SIZE * x);
                 if (avctx->debug & FF_DEBUG_SKIP) {
                     int count = mbskip_table ? mbskip_table[x + y * mb_stride] : 0;
                     if (count > 9)
                         count = 9;
-                    av_log(avctx, AV_LOG_DEBUG, "%1d", count);
+                    *mbs++ = '0' + count;
                 }
                 if (avctx->debug & FF_DEBUG_QP) {
-                    av_log(avctx, AV_LOG_DEBUG, "%2d",
-                           qscale_table[x + y * mb_stride]);
+                    int q = qscale_table[x + y * mb_stride];
+                    *mbs++ = '0' + q/10;
+                    *mbs++ = '0' + q%10;
                 }
                 if (avctx->debug & FF_DEBUG_MB_TYPE) {
                     int mb_type = mbtype_table[x + y * mb_stride];
                     // Type & MV direction
                     if (IS_PCM(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "P");
+                        *mbs++ = 'P';
                     else if (IS_INTRA(mb_type) && IS_ACPRED(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "A");
+                        *mbs++ = 'A';
                     else if (IS_INTRA4x4(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "i");
+                        *mbs++ = 'i';
                     else if (IS_INTRA16x16(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "I");
+                        *mbs++ = 'I';
                     else if (IS_DIRECT(mb_type) && IS_SKIP(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "d");
+                        *mbs++ = 'd';
                     else if (IS_DIRECT(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "D");
+                        *mbs++ = 'D';
                     else if (IS_GMC(mb_type) && IS_SKIP(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "g");
+                        *mbs++ = 'g';
                     else if (IS_GMC(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "G");
+                        *mbs++ = 'G';
                     else if (IS_SKIP(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "S");
+                        *mbs++ = 'S';
                     else if (!USES_LIST(mb_type, 1))
-                        av_log(avctx, AV_LOG_DEBUG, ">");
+                        *mbs++ = '>';
                     else if (!USES_LIST(mb_type, 0))
-                        av_log(avctx, AV_LOG_DEBUG, "<");
+                        *mbs++ = '<';
                     else {
                         av_assert2(USES_LIST(mb_type, 0) && USES_LIST(mb_type, 1));
-                        av_log(avctx, AV_LOG_DEBUG, "X");
+                        *mbs++ = 'X';
                     }
 
                     // segmentation
                     if (IS_8X8(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "+");
+                        *mbs++ = '+';
                     else if (IS_16X8(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "-");
+                        *mbs++ = '-';
                     else if (IS_8X16(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "|");
+                        *mbs++ = '|';
                     else if (IS_INTRA(mb_type) || IS_16X16(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, " ");
+                        *mbs++ = ' ';
                     else
-                        av_log(avctx, AV_LOG_DEBUG, "?");
+                        *mbs++ = '?';
 
 
                     if (IS_INTERLACED(mb_type))
-                        av_log(avctx, AV_LOG_DEBUG, "=");
+                        *mbs++ = '=';
                     else
-                        av_log(avctx, AV_LOG_DEBUG, " ");
+                        *mbs++ = ' ';
                 }
             }
-            av_log(avctx, AV_LOG_DEBUG, "\n");
+            *mbs++ = 0;
+            av_log(avctx, AV_LOG_DEBUG, "%s\n", mbstring);
         }
+        av_freep(&mbstring);
     }
 }
-- 
2.17.1