[FFmpeg-devel] [PATCH]lavfi/avfiltergraph: Do not return ENOMEM if filter is missing

[James Almer]

On 2/4/2018 10:33 PM, Carl Eugen Hoyos wrote:
> Hi!
> 
> OOM is unlikely as a failure for avfilter_graph_alloc_filter(), the
> patch avoids a surprising error if a filter was not found.
> 
> Please comment, Carl Eugen
> 
> 
> 0001-lavfi-avfiltergraph-Do-not-return-ENOMEM-if-filterch.patch
> 
> 
> From 6587726a5e96570bb54e49ccf0b7fd6d94b929c8 Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
> Date: Mon, 5 Feb 2018 01:43:08 +0100
> Subject: [PATCH] lavfi/avfiltergraph: Do not return ENOMEM if filterchain
>  init failed.
> 
> A more likely reason is that the filter was not found.
> ---
>  libavfilter/avfiltergraph.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
> index 4cc6892..7ccd895 100644
> --- a/libavfilter/avfiltergraph.c
> +++ b/libavfilter/avfiltergraph.c
> @@ -147,7 +147,7 @@ int avfilter_graph_create_filter(AVFilterContext **filt_ctx, const AVFilter *fil
>  
>      *filt_ctx = avfilter_graph_alloc_filter(graph_ctx, filt, name);
>      if (!*filt_ctx)
> -        return AVERROR(ENOMEM);
> +        return -1;

-1 is not acceptable for a public function that states it returns an
AVERROR value on failure.
If the issue is that avfilter_graph_alloc_filter() may fail because of
both OOM and an invalid value for filter, then I'm more inclined to use
AVERROR_UNKNOWN here instead.

That being said, based on the above the return value of
avfilter_graph_alloc_filter() should have never been an AVFilterContext,
but an int instead.
Maybe a new function that returns a proper AVERROR value should be
added. AVERROR(ENOMEM), AVERROR(EINVAL), AVERROR_FILTER_NOT_FOUND, or
whatever corresponds depending on the type of failure.

>  
>      ret = avfilter_init_str(*filt_ctx, args);
>      if (ret < 0)
> -- 1.7.10.4
> 
> 
> 
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>