[PATCH v2 1/2] posix/group_member: Add group_member2 with error return.

[Joe Simmons-Talbott]

On Sat, Oct 14, 2023 at 10:52:25AM +0200, Florian Weimer wrote:
> * Joe Simmons-Talbott:
> 
> > index 22422b1f9f..6064eb7264 100644
> > --- a/posix/group_member.c
> > +++ b/posix/group_member.c
> > @@ -16,6 +16,8 @@
> >     License along with the GNU C Library; if not, see
> >     <https://www.gnu.org/licenses/>.  */
> >  
> > +#include <errno.h>
> > +#include <scratch_buffer.h>
> >  #include <sys/types.h>
> >  #include <unistd.h>
> >  #include <stdlib.h>
> > @@ -47,3 +49,33 @@ __group_member (gid_t gid)
> >    return 0;
> >  }
> >  weak_alias (__group_member, group_member)
> > +
> > +int
> > +__group_member2 (gid_t gid)
> > +{
> > +  int n;
> > +  gid_t *groups;
> > +  struct scratch_buffer buf;
> > +  scratch_buffer_init (&buf);
> > +
> > +  n = __getgroups (0, NULL);
> > +  if (!scratch_buffer_set_array_size (&buf, n, sizeof (*groups)))
> > +    {
> > +      errno = ENOMEM;
> > +      return -1;
> > +    }
> > +  groups = buf.data;
> > +
> > +  n = __getgroups (n, groups);
> > +
> > +  while (n-- > 0)
> > +    if (groups[n] == gid)
> > +      {
> > +        scratch_buffer_free (&buf);
> > +        return 1;
> > +      }
> > +
> > +  scratch_buffer_free (&buf);
> > +  return 0;
> > +}
> > +weak_alias (__group_member2, group_member2)
> 
> This three-state return value (0/1/-1) is very difficult to deal with
> for programmers, especially since we are coming from a boolean
> interface.  I'm not sure if this kind of interface is a good idea.

Okay.  I'll post a new version of the deprecation only patch with the
changes Joseph suggested for group_member.h

Thanks,
Joe