From 1c3533367188ea25bace9dedd6ee63fb1112b14d Mon Sep 17 00:00:00 2001 From: Marth64 Date: Tue, 2 Apr 2024 00:24:53 -0500 Subject: [PATCH] avformat/subtitles: extend ff_subtitles_queue_insert() to support not yet available events If ff_subtitles_queue_insert() were given a NULL buffer with 0 length, it would still attempt to grow the packet or memcpy depending on if merge option is enabled. In this commit, allow passing a NULL buffer with 0 length without attempting to do such operations. This way, if a subtitle demuxer happens to pass an empty cue or wants to use av_get_packet() to read bytes, there are no unnecessary operations on the packet after it is allocated. Signed-off-by: Marth64 --- libavformat/subtitles.c | 23 +++++++++++++++-------- libavformat/subtitles.h | 2 +- 2 files changed, 16 insertions(+), 9 deletions(-) diff --git a/libavformat/subtitles.c b/libavformat/subtitles.c index d7723c497f..69e4df88a3 100644 --- a/libavformat/subtitles.c +++ b/libavformat/subtitles.c @@ -21,6 +21,7 @@ #include "avformat.h" #include "subtitles.h" #include "avio_internal.h" +#include "libavutil/avassert.h" #include "libavutil/avstring.h" #include "libavutil/mem.h" @@ -112,15 +113,19 @@ AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, { AVPacket **subs, *sub; + av_assert1(event || len == 0); + if (merge && q->nb_subs > 0) { /* merge with previous event */ int old_len; sub = q->subs[q->nb_subs - 1]; old_len = sub->size; - if (av_grow_packet(sub, len) < 0) - return NULL; - memcpy(sub->data + old_len, event, len); + if (event) { + if (av_grow_packet(sub, len) < 0) + return NULL; + memcpy(sub->data + old_len, event, len); + } } else { /* new event */ @@ -134,14 +139,16 @@ AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, sub = av_packet_alloc(); if (!sub) return NULL; - if (av_new_packet(sub, len) < 0) { - av_packet_free(&sub); - return NULL; + if (event) { + if (av_new_packet(sub, len) < 0) { + av_packet_free(&sub); + return NULL; + } + memcpy(sub->data, event, len); } - subs[q->nb_subs++] = sub; sub->flags |= AV_PKT_FLAG_KEY; sub->pts = sub->dts = 0; - memcpy(sub->data, event, len); + subs[q->nb_subs++] = sub; } return sub; } diff --git a/libavformat/subtitles.h b/libavformat/subtitles.h index 88665663c5..ad6b96ca6a 100644 --- a/libavformat/subtitles.h +++ b/libavformat/subtitles.h @@ -112,7 +112,7 @@ typedef struct { /** * Insert a new subtitle event. * - * @param event the subtitle line, may not be zero terminated + * @param event the subtitle line (not zero terminated) or NULL on not yet available event * @param len the length of the event (in strlen() sense, so without '\0') * @param merge set to 1 if the current event should be concatenated with the * previous one instead of adding a new entry, 0 otherwise