-/* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, 0) always fails.
- On other systems, it returns the number of supplemental groups for the
- process. This function handles that special case and lets the system-
- provided function handle all others. */
+/* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, NULL) always
+ fails. On other systems, it returns the number of supplemental
+ groups for the process. This function handles that special case
+ and lets the system-provided function handle all others. However,
+ it can fail with ENOMEM if memory is tight. It is unspecified
+ whether the effective group id is included in the list. */