Now that we can determine the terminal even when file descriptors

are redirected we can check user_ttypath rather than opening
/dev/tty when enforcing requiretty.

plugins/sudoers/sudoers.c

@@ -324,14 +324,10 @@ sudoers_policy_main(int argc, char * const argv[], int pwflag, char *env_add[],
     }
 
     /* Bail if a tty is required and we don't have one.  */
-    if (def_requiretty) {
-	int fd = open(_PATH_TTY, O_RDWR|O_NOCTTY);
-	if (fd == -1) {
+    if (def_requiretty && user_ttypath == NULL) {
 	audit_failure(NewArgv, N_("no tty"));
 	warningx(_("sorry, you must have a tty to run sudo"));
 	goto bad;
-	} else
-	    (void) close(fd);
     }
 
     /*