From 09683f46b9a3cfb95650b7db4eeaf9533ebb99cc Mon Sep 17 00:00:00 2001
From: Jilles Tjoelker <jilles@FreeBSD.org>
Date: Fri, 31 Dec 2010 18:20:17 +0000
Subject: [PATCH] sh: Check if dup2 for redirection from/to a file succeeds.

A failure (e.g. caused by ulimit -n being set very low) is a redirection
error.

Example:
  ulimit -n 9; exec 9<.
---
 bin/sh/redir.c                                      | 7 ++++++-
 tools/regression/bin/sh/errors/redirection-error7.0 | 7 +++++++
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 tools/regression/bin/sh/errors/redirection-error7.0

diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index 4f0a40c87095..6e6f7a5a74dc 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -155,6 +155,7 @@ openredirect(union node *redir, char memory[10])
 	int fd = redir->nfile.fd;
 	char *fname;
 	int f;
+	int e;
 
 	/*
 	 * We suppress interrupts so that we won't leave open file
@@ -173,7 +174,11 @@ openredirect(union node *redir, char memory[10])
 			error("cannot open %s: %s", fname, strerror(errno));
 movefd:
 		if (f != fd) {
-			dup2(f, fd);
+			if (dup2(f, fd) == -1) {
+				e = errno;
+				close(f);
+				error("%d: %s", fd, strerror(e));
+			}
 			close(f);
 		}
 		break;
diff --git a/tools/regression/bin/sh/errors/redirection-error7.0 b/tools/regression/bin/sh/errors/redirection-error7.0
new file mode 100644
index 000000000000..5b20f04beb83
--- /dev/null
+++ b/tools/regression/bin/sh/errors/redirection-error7.0
@@ -0,0 +1,7 @@
+# $FreeBSD$
+
+! dummy=$(
+	exec 3>&1 >&2 2>&3
+	ulimit -n 9
+	exec 9<.
+) && [ -n "$dummy" ]