sh: Fix the trap builtin to be POSIX-compliant for 'trap exit SIG' and 'trap n n...'.

The parser considered 'trap exit INT' to reset the default for both EXIT and
INT. This beahvior is not POSIX compliant. This was avoided if a value was
specified for 'exit', but then disallows exiting with the signal received. A
possible workaround is using ' exit'.

However POSIX does allow this type of behavior if the parameters are all
integers. Fix the handling for this and clarify its support in the manpage
since it is specifically allowed by POSIX.

Differential Revision:	https://reviews.freebsd.org/D2325
Reviewed by:	jilles
MFC after:	2 weeks

5 files changed, 30 insertions, 4 deletions

diff --git a/bin/sh/sh.1 b/bin/sh/sh.1
index b22a98f..e5707c0 100644
--- a/bin/sh/sh.1
+++ b/bin/sh/sh.1
@@ -32,7 +32,7 @@
 .\"	from: @(#)sh.1	8.6 (Berkeley) 5/4/95
 .\" $FreeBSD$
 .\"
-.Dd February 22, 2015
+.Dd April 18, 2015
 .Dt SH 1
 .Os
 .Sh NAME
@@ -2574,8 +2574,7 @@ the former causes the specified signal to be ignored
 and the latter causes the default action to be taken.
 Omitting the
 .Ar action
-is another way to request the default action, for compatibility reasons this
-usage is not recommended though.
+and using only signal numbers is another way to request the default action.
 In a subshell or utility environment,
 the shell resets trapped (but not ignored) signals to the default action.
 The
diff --git a/bin/sh/tests/builtins/Makefile b/bin/sh/tests/builtins/Makefile
index 5f5da4a..ad39aac 100644
--- a/bin/sh/tests/builtins/Makefile
+++ b/bin/sh/tests/builtins/Makefile
@@ -137,6 +137,8 @@ FILES+=		trap11.0
 FILES+=		trap12.0
 FILES+=		trap13.0
 FILES+=		trap14.0
+FILES+=		trap15.0
+FILES+=		trap16.0
 FILES+=		trap2.0
 FILES+=		trap3.0
 FILES+=		trap4.0
diff --git a/bin/sh/tests/builtins/trap15.0 b/bin/sh/tests/builtins/trap15.0
new file mode 100644
index 0000000..6b9857d
--- /dev/null
+++ b/bin/sh/tests/builtins/trap15.0
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+(${SH} -c 'term(){ exit 5;}; trap term TERM; kill -TERM $$') &
+wait >/dev/null 2>&1 $!
+[ $? -eq 5 ]
diff --git a/bin/sh/tests/builtins/trap16.0 b/bin/sh/tests/builtins/trap16.0
new file mode 100644
index 0000000..3d70cce
--- /dev/null
+++ b/bin/sh/tests/builtins/trap16.0
@@ -0,0 +1,20 @@
+# $FreeBSD$
+
+traps=$(${SH} -c 'trap "echo bad" 0; trap - 0; trap')
+[ -z "$traps" ] || exit 1
+traps=$(${SH} -c 'trap "echo bad" 0; trap "" 0; trap')
+expected_traps=$(${SH} -c 'trap "" EXIT; trap')
+[ "$traps" = "$expected_traps" ] || exit 2
+traps=$(${SH} -c 'trap "echo bad" 0; trap 0; trap')
+[ -z "$traps" ] || exit 3
+traps=$(${SH} -c 'trap "echo bad" 0; trap -- 0; trap')
+[ -z "$traps" ] || exit 4
+traps=$(${SH} -c 'trap "echo bad" 0 1 2; trap - 0 1 2; trap')
+[ -z "$traps" ] || exit 5
+traps=$(${SH} -c 'trap "echo bad" 0 1 2; trap "" 0 1 2; trap')
+expected_traps=$(${SH} -c 'trap "" EXIT HUP INT; trap')
+[ "$traps" = "$expected_traps" ] || exit 6
+traps=$(${SH} -c 'trap "echo bad" 0 1 2; trap 0 1 2; trap')
+[ -z "$traps" ] || exit 7
+traps=$(${SH} -c 'trap "echo bad" 0 1 2; trap -- 0 1 2; trap')
+[ -z "$traps" ] || exit 8
diff --git a/bin/sh/trap.c b/bin/sh/trap.c
index 4a185b4..f562e27 100644
--- a/bin/sh/trap.c
+++ b/bin/sh/trap.c
@@ -183,7 +183,7 @@ trapcmd(int argc __unused, char **argv)
 		return 0;
 	}
 	action = NULL;
-	if (*argv && sigstring_to_signum(*argv) == -1) {
+	if (*argv && !is_number(*argv)) {
 		if (strcmp(*argv, "-") == 0)
 			argv++;
 		else {