Ensure that the TTY file descriptor is greater than or equal to 10 so that

it doesn't interfere with the user's redirections.

PR:		47136
MFC after:	1 week

1 files changed, 14 insertions, 1 deletions

diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index cdd921b..0c1518d 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -126,9 +126,22 @@ setjobctl(int on)
 			i = 0;
 			while (i <= 2 && !isatty(i))
 				i++;
-			if (i > 2 || (ttyfd = dup(i)) < 0)
+			if (i > 2 || (ttyfd = fcntl(i, F_DUPFD, 10)) < 0)
 				goto out;
 		}
+		if (ttyfd < 10) {
+			/*
+			 * Keep our TTY file descriptor out of the way of
+			 * the user's redirections.
+			 */
+			if ((i = fcntl(ttyfd, F_DUPFD, 10)) < 0) {
+				close(ttyfd);
+				ttyfd = -1;
+				goto out;
+			}
+			close(ttyfd);
+			ttyfd = i;
+		}
 		if (fcntl(ttyfd, F_SETFD, FD_CLOEXEC) < 0) {
 			close(ttyfd);
 			ttyfd = -1;