--- /dev/null
+--- termios.c.orig 2007-03-16 00:36:09.000000000 -0700
++++ termios.c 2007-03-16 00:45:15.000000000 -0700
+@@ -37,6 +37,14 @@
+ #include <sys/cdefs.h>
+ __FBSDID("$FreeBSD: src/lib/libc/gen/termios.c,v 1.13 2002/05/28 16:59:39 alfred Exp $");
+
++#if __DARWIN_UNIX03
++#ifdef VARIANT_CANCELABLE
++#include <pthread.h>
++
++extern void _pthread_testcancel(pthread_t thread, int isconforming);
++#endif /* VARIANT_CANCELABLE */
++#endif /* __DARWIN_UNIX03 */
++
+ #include "namespace.h"
+ #include <sys/types.h>
+ #include <sys/fcntl.h>
+@@ -48,6 +56,7 @@
+ #include <unistd.h>
+ #include "un-namespace.h"
+
++#ifndef BUILDING_VARIANT
+ int
+ tcgetattr(fd, t)
+ int fd;
+@@ -87,6 +96,9 @@
+ {
+ int s;
+
++ if (isatty(fd) == 0)
++ return (-1);
++
+ s = pgrp;
+ return (_ioctl(fd, TIOCSPGRP, &s));
+ }
+@@ -97,6 +109,9 @@
+ {
+ int s;
+
++ if (isatty(fd) == 0)
++ return ((pid_t)-1);
++
+ if (_ioctl(fd, TIOCGPGRP, &s) < 0)
+ return ((pid_t)-1);
+
+@@ -183,17 +198,24 @@
+ return (-1);
+ return (0);
+ }
++#endif /* BUILDING_VARIANT */
+
+ int
+ __tcdrain(fd)
+ int fd;
+ {
++#if __DARWIN_UNIX03
++#ifdef VARIANT_CANCELABLE
++ _pthread_testcancel(pthread_self(), 1);
++#endif /* VARIANT_CANCELABLE */
++#endif /* __DARWIN_UNIX03 */
+ return (_ioctl(fd, TIOCDRAIN, 0));
+ }
+
+ __weak_reference(__tcdrain, tcdrain);
+ __weak_reference(__tcdrain, _tcdrain);
+
++#ifndef BUILDING_VARIANT
+ int
+ tcflush(fd, which)
+ int fd, which;
+@@ -230,16 +252,13 @@
+ case TCOON:
+ return (_ioctl(fd, TIOCSTART, 0));
+ case TCION:
++ return (_ioctl(fd, TIOCIXON, 0));
+ case TCIOFF:
+- if (tcgetattr(fd, &term) == -1)
+- return (-1);
+- c = term.c_cc[action == TCIOFF ? VSTOP : VSTART];
+- if (c != _POSIX_VDISABLE && _write(fd, &c, sizeof(c)) == -1)
+- return (-1);
+- return (0);
++ return (_ioctl(fd, TIOCIXOFF, 0));
+ default:
+ errno = EINVAL;
+ return (-1);
+ }
+ /* NOTREACHED */
+ }
++#endif /* BUILDING_VARIANT */