[FFmpeg-devel] [PATCH v1] fftools/ffplay: Resolve input file path before processing

[Nicolas George]

Appaji (HE12025-05-14):
> Fixes ticket: https://trac.ffmpeg.org/ticket/11574
> 
> Signed-off-by: Appaji <appaji12368 at gmail.com>
> ---
>  fftools/ffplay.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/fftools/ffplay.c b/fftools/ffplay.c
> index 2a572fc3aa..42f0584b55 100644
> --- a/fftools/ffplay.c
> +++ b/fftools/ffplay.c
> @@ -27,6 +27,7 @@
>  #include "config_components.h"
>  #include <math.h>
>  #include <limits.h>
> +#include <stdlib.h>
>  #include <signal.h>
>  #include <stdint.h>
>  
> @@ -3623,9 +3624,17 @@ static int opt_input_file(void *optctx, const char *filename)
>                  filename, input_filename);
>          return AVERROR(EINVAL);
>      }
> -    if (!strcmp(filename, "-"))
> +
> +    char resolved_path[PATH_MAX];
> +
> +    if (!realpath(filename, resolved_path)) {
> +        av_log(NULL, AV_LOG_FATAL, "Failed to resolve path for '%s': %s\n", filename, strerror(errno));
> +        return AVERROR(errno);
> +    }
> +

Hi. Thanks for the patch. Did you test it with non-filenames arguments,
for example http://…?

> +    if (!strcmp(resolved_path, "-"))
>          filename = "fd:";

This should happen before resolution.

> -    input_filename = av_strdup(filename);
> +    input_filename = av_strdup(resolved_path);
>      if (!input_filename)
>          return AVERROR(ENOMEM);
>  

On the whole, I think you are going at it wrong: you are only fixing
this for ffplay, not for ffprobe, ffmpeg and other applications built on
the libraries, and resolving the path can have side effects, for example
if you do not have permission on a parent of the current working
directory.

IMO, the correct way would be to add a stat() early in the opening of
the file and test the device number. But that requires changing quite a
lot of things.

Regards,

-- 
  Nicolas George