use tame "stdio rpath tty", for ttyname(). from Rob Pierce, who chose to

do this using ktrace step by step.  not the method i recommend, because
it requires 100% coverage via feature tests.  better to read the code and
understand everything being called, then make decisions.

diff --git a/usr.bin/tty/tty.c b/usr.bin/tty/tty.c
index 5243afd..e7c4518 100644 (file)
--- a/usr.bin/tty/tty.c
+++ b/usr.bin/tty/tty.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tty.c,v 1.7 2013/11/27 13:32:02 okan Exp $    */
+/*     $OpenBSD: tty.c,v 1.8 2015/10/07 18:00:06 deraadt Exp $ */
 /*     $NetBSD: tty.c,v 1.4 1994/12/07 00:46:57 jtc Exp $      */
 
 /*
@@ -33,6 +33,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <err.h>
 
 static void usage(void);
 
@@ -42,6 +43,9 @@ main(int argc, char *argv[])
        int ch, sflag;
        char *t;
 
+       if (tame("stdio rpath tty", NULL) == -1)
+               err(1, "tame");
+
        sflag = 0;
        while ((ch = getopt(argc, argv, "s")) != -1) {
                switch(ch) {
@@ -61,7 +65,6 @@ main(int argc, char *argv[])
        exit(t ? 0 : 1);
 }
 
-
 static void
 usage(void)
 {