From edd35de39a456c900054b66f8bbb0db6c0a25709 Mon Sep 17 00:00:00 2001
From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Sat, 6 Jun 2015 19:44:29 -0700
Subject: [PATCH] sh - Sync to FreeBSD d038ee76 part 2/2 (d)

Reapply 330497ceac - fix O_CLOEXEC race in open() and fhopen()

* Fix an O_CLOEXEC race where a fork/exec can race an open(...O_CLOEXEC)
  and improperly inherit the descriptor.
---
 bin/sh/input.c |  7 +++++--
 bin/sh/jobs.c  | 15 +++++++++++----
 bin/sh/main.c  |  2 +-
 bin/sh/redir.c |  7 ++++++-
 bin/sh/shell.h | 16 ++++++++++++++++
 5 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/bin/sh/input.c b/bin/sh/input.c
index 8117e755e4..80630980e0 100644
--- a/bin/sh/input.c
+++ b/bin/sh/input.c
@@ -368,10 +368,10 @@ setinputfile(const char *fname, int push)
 	int fd2;
 
 	INTOFF;
-	if ((fd = open(fname, O_RDONLY | O_CLOEXEC)) < 0)
+	if ((fd = open(fname, O_RDONLY | O_CLOEXEC_MAYBE)) < 0)
 		error("cannot open %s: %s", fname, strerror(errno));
 	if (fd < 10) {
-		fd2 = fcntl(fd, F_DUPFD_CLOEXEC, 10);
+		fd2 = fcntl(fd, F_DUPFD_CLOEXEC_MAYBE, 10);
 		close(fd);
 		if (fd2 < 0)
 			error("Out of file descriptors");
@@ -390,6 +390,9 @@ setinputfile(const char *fname, int push)
 void
 setinputfd(int fd, int push)
 {
+#if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
+	fcntl(fd, F_SETFD, FD_CLOEXEC);
+#endif
 	if (push) {
 		pushfile();
 		parsefile->buf = ckmalloc(BUFSIZ + 1);
diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index 59dc0431f0..a5d97d955a 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -146,12 +146,12 @@ setjobctl(int on)
 	if (on) {
 		if (ttyfd != -1)
 			close(ttyfd);
-		if ((ttyfd = open(_PATH_TTY, O_RDWR | O_CLOEXEC)) < 0) {
+		if ((ttyfd = open(_PATH_TTY, O_RDWR | O_CLOEXEC_MAYBE)) < 0) {
 			i = 0;
 			while (i <= 2 && !isatty(i))
 				i++;
 			if (i > 2 ||
-			    (ttyfd = fcntl(i, F_DUPFD_CLOEXEC, 10)) < 0) {
+			    (ttyfd = fcntl(i, F_DUPFD_CLOEXEC_MAYBE, 10)) < 0) {
 				jobctl_notty();
 				return;
 			}
@@ -161,17 +161,24 @@ setjobctl(int on)
 			 * Keep our TTY file descriptor out of the way of
 			 * the user's redirections.
 			 */
-			if ((i = fcntl(ttyfd, F_DUPFD_CLOEXEC, 10)) < 0) {
+			if ((i = fcntl(ttyfd, F_DUPFD_CLOEXEC_MAYBE, 10)) < 0) {
 				jobctl_notty();
 				return;
 			}
 			close(ttyfd);
 			ttyfd = i;
 		}
+#if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
+		if (fcntl(ttyfd, F_SETFD, FD_CLOEXEC) < 0) {
+			close(ttyfd);
+			ttyfd = -1;
+			goto out;
+		}
+#endif
 		do { /* while we are in the background */
 			initialpgrp = tcgetpgrp(ttyfd);
 			if (initialpgrp < 0) {
-				jobctl_notty();
+out:				jobctl_notty();
 				return;
 			}
 			if (initialpgrp != getpgrp()) {
diff --git a/bin/sh/main.c b/bin/sh/main.c
index c483d19b41..7f01d2b331 100644
--- a/bin/sh/main.c
+++ b/bin/sh/main.c
@@ -257,7 +257,7 @@ read_profile(const char *name)
 	if (expandedname == NULL)
 		return;
 	INTOFF;
-	if ((fd = open(expandedname, O_RDONLY | O_CLOEXEC)) >= 0)
+	if ((fd = open(expandedname, O_RDONLY | O_CLOEXEC_MAYBE)) >= 0)
 		setinputfd(fd, 1);
 	INTON;
 	if (fd < 0)
diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index 674c150eb2..a3327236d7 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -132,7 +132,7 @@ redirect(union node *redir, int flags)
 
 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
 			INTOFF;
-			if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
+			if ((i = fcntl(fd, F_DUPFD_CLOEXEC_MAYBE, 10)) == -1) {
 				switch (errno) {
 				case EBADF:
 					i = CLOSED;
@@ -143,6 +143,11 @@ redirect(union node *redir, int flags)
 					break;
 				}
 			}
+#if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
+			else {
+				fcntl(i, F_SETFD, FD_CLOEXEC);
+			}
+#endif
 			sv->renamed[fd] = i;
 			INTON;
 		}
diff --git a/bin/sh/shell.h b/bin/sh/shell.h
index 74f11a33fd..a628d351d9 100644
--- a/bin/sh/shell.h
+++ b/bin/sh/shell.h
@@ -52,6 +52,22 @@
 #define	JOBS 1
 /* #define DEBUG 1 */
 
+/*
+ * Allow compilation with older versions of DragonFly or on
+ * systems without these features.
+ */
+#ifdef F_DUPFD_CLOEXEC
+#define F_DUPFD_CLOEXEC_MAYBE	F_DUPFD_CLOEXEC
+#else
+#define F_DUPFD_CLOEXEC_MAYBE	F_DUPFD
+#endif
+
+#ifdef O_CLOEXEC
+#define O_CLOEXEC_MAYBE		O_CLOEXEC
+#else
+#define O_CLOEXEC_MAYBE		0
+#endif
+
 /*
  * Type of used arithmetics. SUSv3 requires us to have at least signed long.
  */
-- 
2.41.0