selftests: forwarding: lib: Move require_command to net, generalize

This helper could be useful to more than just forwarding tests.
Move it upstairs and port over to log_test_skip().

Split the function into two parts: the bit that actually checks and
reports skip, which is in a new function check_command(). And a bit
that exits the test script if the check fails. This allows users
consistent checking behavior while giving an option to bail out from
a single test without bailing out of the whole script.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/forwarding/lib.sh

@@ -291,16 +291,6 @@ if [[ "$CHECK_TC" = "yes" ]]; then
 	check_tc_version
 fi
 
-require_command()
-{
-	local cmd=$1; shift
-
-	if [[ ! -x "$(command -v "$cmd")" ]]; then
-		echo "SKIP: $cmd not installed"
-		exit $ksft_skip
-	fi
-}
-
 # IPv6 support was added in v3.0
 check_mtools_version()
 {

tools/testing/selftests/net/lib.sh

@@ -450,6 +450,25 @@ kill_process()
 	{ kill $pid && wait $pid; } 2>/dev/null
 }
 
+check_command()
+{
+	local cmd=$1; shift
+
+	if [[ ! -x "$(command -v "$cmd")" ]]; then
+		log_test_skip "$cmd not installed"
+		return $EXIT_STATUS
+	fi
+}
+
+require_command()
+{
+	local cmd=$1; shift
+
+	if ! check_command "$cmd"; then
+		exit $EXIT_STATUS
+	fi
+}
+
 ip_link_add()
 {
 	local name=$1; shift