Re: Problem with id when mgetgroups returns no groups.

[Jim Meyering]

Eric Blake wrote:
> Eric Blake <ebb9 <at> byu.net> writes:
>
>> Thanks for your report.  Indeed, looking at mgetgroups.c, if getgroups
>> fails, mgetgroups returns -1 without assigning through *groups (likewise
>> if realloc_groupbug fails, but that sets errno to ENOMEM).  I also wonder
>> if mgetgroups should be taught to recognize ENOSYS itself, and guarantee a
>> zero-length array rather than returning with -1 in that case.
>
> I spotted another problem - id was not handling ENOMEM failures consistently
> (in other words, it didn't go through xalloc_die).
>
> How about this alternative patch, which makes gnulib aware of ENOSYS, and
> changes coreutils to use the more robust interface?
>
>
> From: Eric Blake <address@hidden>
> Date: Fri, 4 Dec 2009 08:26:23 -0700
> Subject: [PATCH] mgetgroups: add xgetgroups, and avoid ENOSYS failures
>
> * lib/mgetgroups.h (xgetgroups): New prototype.
> * lib/mgetgroups.c (xgetgroups): New wrapper.
> (mgetgroups): Handle ENOSYS.
> * modules/mgetgroups (Depends-on): Add realloc-posix.
> Reported by Scott <scott.gnu.2009 AT scottrix.co.uk>.
...
>
> From: Eric Blake <address@hidden>
> Date: Fri, 4 Dec 2009 08:06:55 -0700
> Subject: [PATCH] id: handle systems without getgroups support
>
> If getgroups failed with ENOSYS, mgetgroups would unnecessarily
> fail, and that provoked id into freeing an uninitialized pointer.
> Meanwhile, we were not using xalloc_die properly.  Both issues
> are better solved in gnulib, by introducing xgetgroups; this
> patch uses the new interface.
>
> * gnulib: Update, for mgetgroups improvments.
> * src/id.c (print_full_info): Adjust caller to die on allocation
> failure, and no longer worry about ENOSYS.
> * src/group-list.c (print_group_list): Likewise.
> * src/setuidgid.c (main): Likewise.

Both look fine.  Thanks!