Re: [PATCH] Fix git init --shared=all on FreeBSD 4.11

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 4, 2008, 00:31 UTC
Message-ID: <7v1w6rfhyn.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <20080303234406.GA28158@steel.home>

Alex Riesen <raa.lkml@gmail.com> writes:

> At least FreeBSD 4.11p2 does not allow changing SUID/GUID bits to
> a non-root user.

Sorry, but I do not understand this change.

Show 10 quoted lines

> diff --git a/path.c b/path.c
> index af27161..4865e98 100644
> --- a/path.c
> +++ b/path.c
> @@ -265,6 +265,7 @@ int adjust_shared_perm(const char *path)
>  		return 0;
>  	if (lstat(path, &st) < 0)
>  		return -1;
> +	st.st_mode &= 07777 & ~(S_ISUID|S_ISGID);
>  	mode = st.st_mode;

If the thing is a directory, we say later in the code that we want to see S_ISGID set, like this:

	...
	if (S_ISDIR(mode))
		mode |= S_ISGID;
	if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
		return -2;
	return 0;

and then we compare with st.st_mode so that we do not chmod() what's already good Your change means we will always try to chmod all the directories, and your explanation suggests that such a chmod to do g+s on directories would also fail (and your patch does not fix it -- we actively try to make sure directories have g+s set).

	Side note. the wording in your message, "does not allow changing",
	is very unclear.  Do you mean "non-root cannot do u+s,g+s"?  Or do
	you mean "non-root cannot do u+s,g+s, non-root cannot do u-s,g-s
	either"?

For regular files, I do not think we have any reason to set u+s or g+s ourselves, and we do not try to do so either. As long as the original st.st_mode does not have such bits set, the mode we will pass to chmod for regular would not try to set them. If you already had u+s,g+s when you read st.st_mode that's a different story, but then I do not know why you had such a file to begin with.

I do not mind a change to make sure we do u-s,g-s on regular files, but I do not think it is necessary, and I am curious why you had files with such perm bits to begin with.