Re: [PATCH] checkpatch: Allow not using -f with files that are in git

[Rasmus Villemoes <linux@rasmusvillemoes.dk>]

On 25/08/2020 02.09, Joe Perches wrote:
> If a file exists in git and checkpatch is used without the -f
> flag for scanning a file, then checkpatch will scan the file
> assuming it's a patch and emit:
> 
> ERROR: Does not appear to be a unified-diff format patch
> 
> Change the behavior to assume the -f flag if the file exists
> in git.

Heh, I read the patch subject to mean you introduced a way for subsystem
maintainers to prevent running checkpatch -f on their files, which I
think some would like ;)

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 79fc357b18cd..cdee7cfadc11 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -976,6 +976,16 @@ sub seed_camelcase_includes {
>  	}
>  }
>  
> +sub git_is_single_file {
> +	my ($filename) = @_;
> +
> +	return 0 if ((which("git") eq "") || !(-e "$gitroot"));
> +
> +	my $output = `${git_command} ls-files -- $filename`;
> +	my $count = $output =~ tr/\n//;
> +	return $count eq 1 && $output =~ m{^${filename}$};
> +}

Isn't that somewhat expensive to do for each file? Why not postpone that
check till we're about to complain that the file is not a diff (haven't
looked at how such a refactoring would look).

Rasmus