+
+DEFUN ("system-users", Fsystem_users, Ssystem_users, 0, 0, 0,
+ doc: /* Return a list of user names currently registered in the system.
+If we don't know how to determine that on this platform, just
+return a list with one element, taken from `user-real-login-name'. */)
+ (void)
+{
+ Lisp_Object users = Qnil;
+#if defined HAVE_GETPWENT && defined HAVE_ENDPWENT
+ struct passwd *pw;
+
+ while ((pw = getpwent ()))
+ users = Fcons (DECODE_SYSTEM (build_string (pw->pw_name)), users);
+
+ endpwent ();
+#endif
+ if (EQ (users, Qnil))
+ /* At least current user is always known. */
+ users = Fcons (Vuser_real_login_name, Qnil);
+ return users;
+}
+
+DEFUN ("system-groups", Fsystem_groups, Ssystem_groups, 0, 0, 0,
+ doc: /* Return a list of user group names currently registered in the system.
+The value may be nil if not supported on this platform. */)
+ (void)
+{
+ Lisp_Object groups = Qnil;
+#if defined HAVE_GETGRENT && defined HAVE_ENDGRENT
+ struct group *gr;
+
+ while ((gr = getgrent ()))
+ groups = Fcons (DECODE_SYSTEM (build_string (gr->gr_name)), groups);
+
+ endgrent ();
+#endif
+ return groups;
+}
+