[FFmpeg-devel] [PATCH] fftools/opt_common: remove dead code in print_buildconf()

[Andreas Rheinhardt]

Marth64:
> I found this code block when looking at this warning thrown in my
> compiler (gcc 11.4.0 x86_64-linux-gnu):
> 
> ```
> In function ‘print_buildconf’,
>     inlined from ‘show_buildconf’ at fftools/opt_common.c:260:5:
> fftools/opt_common.c:226:49: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
>   226 |         remove_tilde[sizeof("pkg-config~") - 2] = ' ';
>       |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
> fftools/opt_common.c: In function ‘show_buildconf’:
> fftools/opt_common.c:214:10: note: at offset [10, 11] into destination object ‘str’ of size 1
>   214 |     char str[] = { FFMPEG_CONFIGURATION };
>       |          ^~~
> ```
> 
> Upon further inspection, I am convinced that remove_tilde does not serve
> a functional purpose. There are no other occurences in the FFmpeg
> tree via grep, and we are setting a value in it but never using.
> The original code traces back to 69cf626f9c1ba29e66ff62e2b835dcfc3031db8d
> and even there, I cannot find a purpose for it.
> 
> Remove the variable and it's related loop where the assignment occurs,
> which resolves the warning.
> 
> Signed-off-by: Marth64 <marth64 at proxyid.net>
> ---
>  fftools/opt_common.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/fftools/opt_common.c b/fftools/opt_common.c
> index 947a226d8d..e4a63f565e 100644
> --- a/fftools/opt_common.c
> +++ b/fftools/opt_common.c
> @@ -212,7 +212,7 @@ static void print_buildconf(int flags, int level)
>  {
>      const char *indent = flags & INDENT ? "  " : "";
>      char str[] = { FFMPEG_CONFIGURATION };
> -    char *conflist, *remove_tilde, *splitconf;
> +    char *conflist, *splitconf;
>  
>      // Change all the ' --' strings to '~--' so that
>      // they can be identified as tokens.
> @@ -220,12 +220,6 @@ static void print_buildconf(int flags, int level)
>          conflist[0] = '~';
>      }
>  
> -    // Compensate for the weirdness this would cause
> -    // when passing 'pkg-config --static'.
> -    while ((remove_tilde = strstr(str, "pkg-config~")) != NULL) {
> -        remove_tilde[sizeof("pkg-config~") - 2] = ' ';
> -    }
> -
>      splitconf = strtok(str, "~");
>      av_log(NULL, level, "\n%sconfiguration:\n", indent);
>      while (splitconf != NULL) {

The code block changes str and str is later accessed (via splitconf).

- Andreas