[FFmpeg-cvslog] lavd/alsa: add stream validation

[Lukasz Marek]

ffmpeg | branch: master | Lukasz Marek <lukasz.m.luki at gmail.com> | Sat Oct 26 01:32:55 2013 +0200| [e56d1a120324fa49a5367cbf22098c5c7eb23f91] | committer: Nicolas George

lavd/alsa: add stream validation

Don't trust provided streams.
Return with error when stream count is not 1 or
provided stream is not an audio stream.

Signed-off-by: Lukasz Marek <lukasz.m.luki at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=e56d1a120324fa49a5367cbf22098c5c7eb23f91
---

 libavdevice/alsa-audio-enc.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavdevice/alsa-audio-enc.c b/libavdevice/alsa-audio-enc.c
index 5033a48..83e1d2f 100644
--- a/libavdevice/alsa-audio-enc.c
+++ b/libavdevice/alsa-audio-enc.c
@@ -47,12 +47,17 @@
 static av_cold int audio_write_header(AVFormatContext *s1)
 {
     AlsaData *s = s1->priv_data;
-    AVStream *st;
+    AVStream *st = NULL;
     unsigned int sample_rate;
     enum AVCodecID codec_id;
     int res;
 
+    if (s1->nb_streams != 1 || s1->streams[0]->codec->codec_type != AVMEDIA_TYPE_AUDIO) {
+        av_log(s1, AV_LOG_ERROR, "Only a single audio stream is supported.\n");
+        return AVERROR(EINVAL);
+    }
     st = s1->streams[0];
+
     sample_rate = st->codec->sample_rate;
     codec_id    = st->codec->codec_id;
     res = ff_alsa_open(s1, SND_PCM_STREAM_PLAYBACK, &sample_rate,