[PATCH v2] selftests/kselftest/runner/run_one(): Allow running non-executable files

[SeongJae Park <sj38.park@gmail.com>]

From: SeongJae Park <sjpark@amazon.de>

When running a test program, 'run_one()' checks if the program has the
execution permission and fails if it doesn't.  However, it's easy to
mistakenly missing the permission, as some common tools like 'diff'
don't support the permission change well[1].  Compared to that, making
mistakes in the test program's path would only rare, as those are
explicitly listed in 'TEST_PROGS'.  Therefore, it might make more sense
to resolve the situation on our own and run the program.

For the reason, this commit makes the test program runner function to
still print the warning message but try parsing the interpreter of the
program and explicitly run it with the interpreter, in the case.

[1] https://lore.kernel.org/mm-commits/YRJisBs9AunccCD4@kroah.com/

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
---
Changes from v1
(https://lore.kernel.org/linux-kselftest/20210810140459.23990-1-sj38.park@gmail.com/)
- Parse and use the interpreter instead of changing the file

 tools/testing/selftests/kselftest/runner.sh | 28 +++++++++++++--------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh
index cc9c846585f0..a9ba782d8ca0 100644
--- a/tools/testing/selftests/kselftest/runner.sh
+++ b/tools/testing/selftests/kselftest/runner.sh
@@ -33,9 +33,9 @@ tap_timeout()
 {
 	# Make sure tests will time out if utility is available.
 	if [ -x /usr/bin/timeout ] ; then
-		/usr/bin/timeout --foreground "$kselftest_timeout" "$1"
+		/usr/bin/timeout --foreground "$kselftest_timeout" $1
 	else
-		"$1"
+		$1
 	fi
 }
 
@@ -65,17 +65,25 @@ run_one()
 
 	TEST_HDR_MSG="selftests: $DIR: $BASENAME_TEST"
 	echo "# $TEST_HDR_MSG"
-	if [ ! -x "$TEST" ]; then
-		echo -n "# Warning: file $TEST is "
-		if [ ! -e "$TEST" ]; then
-			echo "missing!"
-		else
-			echo "not executable, correct this."
-		fi
+	if [ ! -e "$TEST" ]; then
+		echo "# Warning: file $TEST is missing!"
 		echo "not ok $test_num $TEST_HDR_MSG"
 	else
+		cmd="./$BASENAME_TEST"
+		if [ ! -x "$TEST" ]; then
+			echo "# Warning: file $TEST is not executable"
+
+			if [ $(head -n 1 "$TEST" | cut -c -2) = "#!" ]
+			then
+				interpreter=$(head -n 1 "$TEST" | cut -c 3-)
+				cmd="$interpreter ./$BASENAME_TEST"
+			else
+				echo "not ok $test_num $TEST_HDR_MSG"
+				return
+			fi
+		fi
 		cd `dirname $TEST` > /dev/null
-		((((( tap_timeout ./$BASENAME_TEST 2>&1; echo $? >&3) |
+		((((( tap_timeout "$cmd" 2>&1; echo $? >&3) |
 			tap_prefix >&4) 3>&1) |
 			(read xs; exit $xs)) 4>>"$logfile" &&
 		echo "ok $test_num $TEST_HDR_MSG") ||
-- 
2.17.1