Add support for set -o pipefail

With the pipefail option set, the exit status of a pipeline is 0 if all
commands succeed, or the return status of the rightmost command that
fails.  This can help stronger error checking, but is not a silver
bullet.  For example, commands will exhibit a non-zero exit status if
they're killed by a SIGPIPE when writing to a pipe.  Yet pipefail was
considered useful enough to be included in the next POSIX standard.

This implementation remembers the value of the pipefail option when
a pipeline is started, as described as option 1) in

  https://www.austingroupbugs.net/view.php?id=789#c4102

Requested by ajacoutot@, ok millert@

1 files changed, 89 insertions, 1 deletions

diff --git a/regress/bin/ksh/obsd-regress.t b/regress/bin/ksh/obsd-regress.t
index d94695111cf..b9b33d17655 100644
--- a/regress/bin/ksh/obsd-regress.t
+++ b/regress/bin/ksh/obsd-regress.t
@@ -1,4 +1,4 @@
-#	$OpenBSD: obsd-regress.t,v 1.11 2020/05/22 08:45:23 anton Exp $
+#	$OpenBSD: obsd-regress.t,v 1.12 2020/07/07 10:33:58 jca Exp $
 
 #
 # ksh regression tests from OpenBSD
@@ -514,3 +514,91 @@ description:
 stdin:
 	kill -s SIGINFO $$
 ---
+
+name: pipeline-pipefail-1
+description:
+	check pipeline return status
+stdin:
+	set -o pipefail
+	true | true
+---
+
+name: pipeline-pipefail-2
+description:
+	check pipeline return status
+stdin:
+	set -o pipefail
+	false | true
+expected-exit: e == 1
+---
+
+name: pipeline-pipefail-3
+description:
+	check pipeline return status
+stdin:
+	set -o pipefail
+	true | false
+expected-exit: e == 1
+---
+
+name: pipeline-pipefail-4
+description:
+	check pipeline return status
+stdin:
+	set -o pipefail
+	! false | true
+---
+
+name: pipeline-pipefail-errexit-1
+description:
+	check pipeline return status
+stdin:
+	set -e
+	false | true
+	echo "ok"
+expected-stdout: ok
+---
+
+name: pipeline-pipefail-errexit-2
+description:
+	check pipeline return status
+stdin:
+	set -e
+	set -o pipefail
+	false | true
+	echo "should not print"
+expected-exit: e == 1
+expected-stdout:
+---
+
+name: pipeline-pipefail-errexit-3
+description:
+	check pipeline return status
+stdin:
+	set -e
+	set -o pipefail
+	false | true || echo "ok"
+expected-stdout: ok
+---
+
+name: pipeline-pipefail-check-time-1
+description:
+	check pipeline return status
+stdin:
+	false | true &
+	p=$!
+	set -o pipefail
+	wait $p
+---
+
+name: pipeline-pipefail-check-time-2
+description:
+	check pipeline return status
+stdin:
+	set -o pipefail
+	false | true &
+	p=$!
+	set +o pipefail
+	wait $p
+expected-exit: e == 1
+---