[libvirt PATCH 06/32] util: use getgrouplist() directly instead of mgetgroups

[Daniel P. Berrangé]

On Mon, Jan 27, 2020 at 06:05:06PM +0100, Pavel Hrdina wrote:
> On Mon, Jan 27, 2020 at 04:42:41PM +0000, Daniel P. Berrangé wrote:
> > On Mon, Jan 27, 2020 at 12:44:01PM +0100, Pavel Hrdina wrote:
> > > On Thu, Jan 23, 2020 at 11:42:59AM +0000, Daniel P. Berrangé wrote:
> > > > The mgetgroups function is a GNULIB custom wrapper around
> > > > getgrouplist(). This implements a simplified version of
> > > > that code directly.
> > > > 
> > > > Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> > > > ---
> > > >  src/internal.h     |  4 ++++
> > > >  src/util/virutil.c | 34 ++++++++++++++++++++++++++++------
> > > >  2 files changed, 32 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/src/util/virutil.c b/src/util/virutil.c
> > > > index 87ca16c088..4bc0aef35f 100644
> > > > --- a/src/util/virutil.c
> > > > +++ b/src/util/virutil.c
> > > > @@ -1000,11 +1004,27 @@ virGetGroupList(uid_t uid, gid_t gid, gid_t **list)
> > > >      /* invalid users have no supplementary groups */
> > > >      if (uid != (uid_t)-1 &&
> > > >          virGetUserEnt(uid, &user, &primary, NULL, NULL, true) >= 0) {
> > > > -        if ((ret = mgetgroups(user, primary, list)) < 0) {
> > > > -            virReportSystemError(errno,
> > > > -                                 _("cannot get group list for '%s'"), user);
> > > > -            ret = -1;
> > > > -            goto cleanup;
> > > > +        int nallocgrps = 10;
> > > > +        gid_t *grps = g_new(gid_t, nallocgrps);
> > > 
> > > This is never used anywhere except in the while loop.
> > 
> > The loop relies on the "grps" pointer being persistent across
> > loop iterations though.
> 
> Sorry, probably bad wording.  I meant that we need to assign the "grps"
> to *lists otherwise it's used only in the loop.

Ok, so your later suggestion/comment addresses that.

> > > > +        while (1) {
> > > > +            int nprevallocgrps = nallocgrps;
> > > > +            int rv;
> > > > +
> > > > +            rv = getgrouplist(user, primary, grps, &nallocgrps);
> > > > +
> > > > +            /* Some systems (like Darwin) have a bug where they
> > > > +               never increase max_n_groups.  */
> > > > +            if (rv < 0 && nprevallocgrps == nallocgrps)
> > > > +                nallocgrps *= 2;
> > > > +
> > > > +            /* either shrinks to actual size, or enlarges tonew size */
> > > 
> > > s/tonew/to new/
> > > 
> > > > +            grps = g_renew(gid_t, grps, nallocgrps);
> > > > +
> > > > +            if (rv >= 0) {
> > > > +                ret = rv;
> > > > +                break;
> > > 
> > > Based on the GNULIB implementation here we should set *list = grps.
> > 
> > Yes.
> > 
> > > 
> > > With that fixed:
> > > 
> > > Reviewed-by: Pavel Hrdina <phrdina at redhat.com>
> > 
> > 
> > 
> > Regards,
> > Daniel
> > -- 
> > |: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
> > |: https://libvirt.org         -o-            https://fstop138.berrange.com :|
> > |: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|



Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|