[libvirt] [PATCH 2/3] new virSetUIDGID() utility function

[Eric Blake]

On 12/23/2010 11:39 AM, Laine Stump wrote:
> virSetUIDGID() sets both the real and effective group and user of the
> process, and additionally calls initgroups() to assure that the
> process joins all the auxiliary groups that the given uid is a member
> of.
> ---
>  src/libvirt_private.syms |    1 +
>  src/util/util.c          |   63 ++++++++++++++++++++++++++++++++++++++++++++++
>  src/util/util.h          |    2 +
>  3 files changed, 66 insertions(+), 0 deletions(-)

I'm guessing that the only code that called this previously was the qemu
driver, in code compiled only for Linux (as the qemu driver is not
compiled for mingw).  Ultimately, it might be nicer to find portable
ways to do the equivalent of initgroups on other platforms that lack the
Linux interface, but do have a way to set supplementary groups (POSIX
doesn't standardize setting supplementary groups on purpose); or even
better, to have gnulib implement initgroups() for as many platforms as
possible.

> +        if (initgroups(pwd.pw_name, pwd.pw_gid) < 0) {
> +            virReportSystemError(errno,
> +                                 _("cannot initgroups(\"%s\", %d)"),
> +                                 pwd.pw_name, pwd.pw_gid);
> +            VIR_FREE(buf);
> +            return -1;
> +        }

My biggest worry is that checking this in will cause compilation
failures on other platforms, so here's hoping we can get the word out
that we need testing, or even modify this patch to add a configure.ac
AC_CHECK_FUNCS_ONCE([initgroups]) and bracket the initgroups() call
within #ifdef HAVE_INITGROUPS (non-Linux platforms won't set
supplementary groups, just the primary gid, but that's better than
failing to compile).  Can you handle that, or would you like me to do
that as a followup commit?

Conditional ACK, based on that answer.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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