avcodec/v4l2_context: suppress POLLERR and fix crash when buffers are uninitialized

A POLLERR occurs when libavcodec attempts to dequeue output buffers
before enqueuing capture buffers. This could happen to an application
deciding to send the first coded packet. Suppress these POLLERRs when
the buffers are uninitialized and avoid crashing because of enumerating
uninitialized buffers.

See https://trac.ffmpeg.org/ticket/9957 for the original bug report.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>
This commit is contained in:
Richard Acayan 2023-07-25 17:38:39 -04:00 committed by Marton Balint
parent 91e1d11d14
commit 4fa1d3e791
1 changed files with 6 additions and 2 deletions

View File

@ -325,9 +325,13 @@ start:
/* 0. handle errors */
if (pfd.revents & POLLERR) {
/* if we are trying to get free buffers but none have been queued yet
no need to raise a warning */
/* if we are trying to get free buffers but none have been queued yet,
* or if no buffers have been allocated yet, no need to raise a warning
*/
if (timeout == 0) {
if (!ctx->buffers)
return NULL;
for (i = 0; i < ctx->num_buffers; i++) {
if (ctx->buffers[i].status != V4L2BUF_AVAILABLE)
av_log(logger(ctx), AV_LOG_WARNING, "%s POLLERR\n", ctx->name);