Fix oom tests on non Linux

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

sys/oom_linux_test.go

@@ -0,0 +1,109 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package sys
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"gotest.tools/v3/assert"
+	is "gotest.tools/v3/assert/cmp"
+)
+
+func TestSetPositiveOomScoreAdjustment(t *testing.T) {
+	_, adjustment, err := adjustOom(123)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	assert.Check(t, is.Equal(adjustment, 123))
+}
+
+func TestSetNegativeOomScoreAdjustmentWhenPrivileged(t *testing.T) {
+	if RunningUnprivileged() {
+		t.Skip("Needs to be run as root")
+		return
+	}
+
+	_, adjustment, err := adjustOom(-123)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	assert.Check(t, is.Equal(adjustment, -123))
+}
+
+func TestSetNegativeOomScoreAdjustmentWhenUnprivilegedHasNoEffect(t *testing.T) {
+	if RunningPrivileged() {
+		t.Skip("Needs to be run as non-root")
+		return
+	}
+
+	initial, adjustment, err := adjustOom(-123)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	assert.Check(t, is.Equal(adjustment, initial))
+}
+
+func adjustOom(adjustment int) (int, int, error) {
+	cmd := exec.Command("sleep", "100")
+	if err := cmd.Start(); err != nil {
+		return 0, 0, err
+	}
+
+	defer cmd.Process.Kill()
+
+	pid, err := waitForPid(cmd.Process)
+	if err != nil {
+		return 0, 0, err
+	}
+	initial, err := GetOOMScoreAdj(pid)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	if err := SetOOMScore(pid, adjustment); err != nil {
+		return 0, 0, err
+	}
+
+	adj, err := GetOOMScoreAdj(pid)
+	return initial, adj, err
+}
+
+func waitForPid(process *os.Process) (int, error) {
+	c := make(chan int, 1)
+	go func() {
+		for {
+			pid := process.Pid
+			if pid != 0 {
+				c <- pid
+			}
+		}
+	}()
+
+	select {
+	case pid := <-c:
+		return pid, nil
+	case <-time.After(10 * time.Second):
+		return 0, errors.New("process did not start in 10 seconds")
+	}
+}