[PATCH v4 5/6] common/config: Introduce _exit wrapper around exit command

["Nirjhar Roy (IBM)" <nirjhar.roy.lists@gmail.com>]

We should always set the value of status correctly when we are exiting.
Else, "$?" might not give us the correct value.
If we see the following trap
handler registration in the check script:

if $OPTIONS_HAVE_SECTIONS; then
     trap "_kill_seq; _summary; exit \$status" 0 1 2 3 15
else
     trap "_kill_seq; _wrapup; exit \$status" 0 1 2 3 15
fi

So, "exit 1" will exit the check script without setting the correct
return value. I ran with the following local.config file:

[xfs_4k_valid]
FSTYP=xfs
TEST_DEV=/dev/loop0
TEST_DIR=/mnt1/test
SCRATCH_DEV=/dev/loop1
SCRATCH_MNT=/mnt1/scratch

[xfs_4k_invalid]
FSTYP=xfs
TEST_DEV=/dev/loop0
TEST_DIR=/mnt1/invalid_dir
SCRATCH_DEV=/dev/loop1
SCRATCH_MNT=/mnt1/scratch

This caused the init_rc() to catch the case of invalid _test_mount
options. Although the check script correctly failed during the execution
of the "xfs_4k_invalid" section, the return value was 0, i.e "echo $?"
returned 0. This is because init_rc exits with "exit 1" without
correctly setting the value of "status". IMO, the correct behavior
should have been that "$?" should have been non-zero.

The next patch will replace exit with _exit.

Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
 common/config | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/common/config b/common/config
index 79bec87f..7dd78dbe 100644
--- a/common/config
+++ b/common/config
@@ -96,6 +96,15 @@ export LOCAL_CONFIGURE_OPTIONS=${LOCAL_CONFIGURE_OPTIONS:=--enable-readline=yes}
 
 export RECREATE_TEST_DEV=${RECREATE_TEST_DEV:=false}
 
+# This functions sets the exit code to status and then exits. Don't use
+# exit directly, as it might not set the value of "$status" correctly, which is
+# used as an exit code in the trap handler routine set up by the check script.
+_exit()
+{
+	test -n "$1" && status="$1"
+	exit "$status"
+}
+
 # Handle mkfs.$fstyp which does (or does not) require -f to overwrite
 set_mkfs_prog_path_with_opts()
 {
-- 
2.34.1