Re: [PATCH] run-command: don't try to execute directories

[Junio C Hamano <gitster@pobox.com>]

Carlos Martín Nieto <cmn@elego.de> writes:

> When looking through $PATH to try to find an external command,
> locate_in_PATH doesn't check that it's trying to execute a file. Add a
> check to make sure we won't try to execute a directory.
>
> This also stops us from looking further and maybe finding that the
> user meant an alias, as in the case where the user has
> /home/user/bin/git-foo/git-foo.pl and an alias
>
>     [alias] foo = !/home/user/bin/git-foo/git-foo.pl
>
> Running 'git foo' will currently will try to execute ~/bin/git-foo and
> fail because you can't execute a directory. By making sure we don't do
> that, we realise that it's an alias and do the right thing
>
> Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
>
> ---
>
> This comes from a case in #git. Not sure if this is worth it, or the
> better solution is just to say no to dirs in $PATH.
>
> After writing all of that, I thought to check the shell, and indeed
>
>     % git-foo
>     zsh: permission denied: git-foo
>
> so if the shell doesn't do it, the benefits probably don't outweigh
> having a dozen stat instead of access calls. strace reveals that zsh
> does what git currently does. bash uses stat and says 'command not
> found'.

Hrm, I do not use zsh but it does not seem to reproduce for me.

	$ mkdir -p /var/tmp/xx/git
        $ zsh
        % PATH=/var/tmp/xx:$PATH
        % type git
        git is /home/junio/bin/git
        % git version
        git version 1.8.0.rc0.45.g7ce8dc5
	% zsh --version
	zsh 4.3.10 (x86_64-unknown-linux-gnu)

> @@ -101,8 +102,9 @@ static char *locate_in_PATH(const char *file)
>  		}
>  		strbuf_addstr(&buf, file);
>  
> -		if (!access(buf.buf, F_OK))
> +		if (!stat(buf.buf, &st) && !S_ISDIR(st.st_mode)) {
>  			return strbuf_detach(&buf, NULL);
> +		}

So we used to say "if it exists and accessible, return that".  Now
we say "if it exists and is not a directory, return that".

I have to wonder what would happen if it exists as a non-directory
but we cannot access it.  Is that a regression?


>  		if (!*end)
>  			break;