[FFmpeg-devel] [PATCH] ffmpeg: check return value of avio_closep for progress report

[James Almer]

On 1/5/2016 12:39 AM, Ganesh Ajjanagadde wrote:
> avio_closep is not guaranteed to succeed, and its return value can
> contain information regarding failure of preceding writes and silent
> loss of data (man 2 close, man fclose). Users should know when the
> progress was not successfully logged, and so a diagnostic is printed
> here.
> 
> The reason only one of these is changed in the patch is to get feedback:
> a quick glance shows a large number of unchecked avio_close operations.
> It may be tedious to check all of them, and relative importance varies
> across instances. This was one which I feel is important.
> 
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ---
>  ffmpeg.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/ffmpeg.c b/ffmpeg.c
> index ee72f91..81f3697 100644
> --- a/ffmpeg.c
> +++ b/ffmpeg.c
> @@ -1512,6 +1512,7 @@ static void print_report(int is_last_report, int64_t timer_start, int64_t cur_ti
>      static int64_t last_time = -1;
>      static int qp_histogram[52];
>      int hours, mins, secs, us;
> +    int ret;
>      float t;
>  
>      if (!print_stats && !is_last_report && !progress_avio)
> @@ -1678,7 +1679,9 @@ static void print_report(int is_last_report, int64_t timer_start, int64_t cur_ti
>          avio_flush(progress_avio);
>          av_bprint_finalize(&buf_script, NULL);
>          if (is_last_report) {
> -            avio_closep(&progress_avio);
> +            if ((ret = avio_closep(&progress_avio)) < 0)
> +                av_log(NULL, AV_LOG_ERROR,
> +                       "not possible to close progress log, loss of information possible: %s\n", av_err2str(ret));

"Unable to close progress log" or "Error closing progress log" sounds better IMO.