From 1cffe8b812e5efda80d7c68dab86d2e1906ef088 Mon Sep 17 00:00:00 2001
From: Jilles Tjoelker <jilles@FreeBSD.org>
Date: Fri, 28 Aug 2020 15:35:45 +0000
Subject: [PATCH] sh: Keep ignored SIGINT/SIGQUIT after set in a background job

If job control is not enabled, a background job (... &) ignores SIGINT and
SIGQUIT, but this can be reverted using the trap builtin in the same shell
environment.

Using the set builtin to change options would also revert SIGINT and SIGQUIT
to their previous dispositions.

This broke due to r317298. Calling setsignal() reverts the effect of
ignoresig().

Reported by:	bdrewery
MFC after:	1 week
---
 bin/sh/main.c                   |  1 +
 bin/sh/tests/execution/Makefile |  1 +
 bin/sh/tests/execution/bg13.0   | 16 ++++++++++++++++
 bin/sh/trap.c                   | 10 ++++++++--
 bin/sh/trap.h                   |  1 +
 5 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 bin/sh/tests/execution/bg13.0

diff --git a/bin/sh/main.c b/bin/sh/main.c
index 8df24dba312e..cbe026e13640 100644
--- a/bin/sh/main.c
+++ b/bin/sh/main.c
@@ -134,6 +134,7 @@ main(int argc, char *argv[])
 	setstackmark(&smark);
 	setstackmark(&smark2);
 	procargs(argc, argv);
+	trap_init();
 	pwd_init(iflag);
 	INTON;
 	if (iflag)
diff --git a/bin/sh/tests/execution/Makefile b/bin/sh/tests/execution/Makefile
index c457c148b8f3..cfc21caf3791 100644
--- a/bin/sh/tests/execution/Makefile
+++ b/bin/sh/tests/execution/Makefile
@@ -19,6 +19,7 @@ ${PACKAGE}FILES+=		bg9.0
 ${PACKAGE}FILES+=		bg10.0 bg10.0.stdout
 ${PACKAGE}FILES+=		bg11.0
 ${PACKAGE}FILES+=		bg12.0
+${PACKAGE}FILES+=		bg13.0
 ${PACKAGE}FILES+=		env1.0
 ${PACKAGE}FILES+=		fork1.0
 ${PACKAGE}FILES+=		fork2.0
diff --git a/bin/sh/tests/execution/bg13.0 b/bin/sh/tests/execution/bg13.0
new file mode 100644
index 000000000000..37a4ad864ded
--- /dev/null
+++ b/bin/sh/tests/execution/bg13.0
@@ -0,0 +1,16 @@
+# $FreeBSD$
+
+T=`mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXXXX`
+trap 'rm -rf $T' 0
+cd $T || exit 3
+mkfifo fifo1
+# Use a trap, not the default action, since the shell may catch SIGINT and
+# therefore its processing may be delayed.
+{ set -C; trap 'exit 5' TERM; read dummy <fifo1; exit 4; } &
+exec 3>fifo1
+kill -INT "$!"
+kill -TERM "$!"
+exec 3>&-
+wait "$!"
+r=$?
+[ "$r" = 5 ]
diff --git a/bin/sh/trap.c b/bin/sh/trap.c
index 1b9ab63f47cb..d7a98604c22c 100644
--- a/bin/sh/trap.c
+++ b/bin/sh/trap.c
@@ -474,14 +474,20 @@ dotrap(void)
 }
 
 
+void
+trap_init(void)
+{
+	setsignal(SIGINT);
+	setsignal(SIGQUIT);
+}
+
+
 /*
  * Controls whether the shell is interactive or not based on iflag.
  */
 void
 setinteractive(void)
 {
-	setsignal(SIGINT);
-	setsignal(SIGQUIT);
 	setsignal(SIGTERM);
 }
 
diff --git a/bin/sh/trap.h b/bin/sh/trap.h
index 63d0bd5e70b1..fdc4b7a9683a 100644
--- a/bin/sh/trap.h
+++ b/bin/sh/trap.h
@@ -45,6 +45,7 @@ void ignoresig(int);
 int issigchldtrapped(void);
 void onsig(int);
 void dotrap(void);
+void trap_init(void);
 void setinteractive(void);
 void exitshell(int) __dead2;
 void exitshell_savedstatus(void) __dead2;