Merge pull request #185 from kinvolk/alessandro/sdnotify

daemon: improve SdNotify errors signaling

daemon/sdnotify.go

@@ -2,30 +2,37 @@
 package daemon
 
 import (
-	"errors"
 	"net"
 	"os"
 )
 
-var SdNotifyNoSocket = errors.New("No socket")
-
 // SdNotify sends a message to the init daemon. It is common to ignore the error.
-func SdNotify(state string) error {
+// It returns one of the following:
+// (false, nil) - notification not supported (i.e. NOTIFY_SOCKET is unset)
+// (false, err) - notification supported, but failure happened (e.g. error connecting to NOTIFY_SOCKET or while sending data)
+// (true, nil) - notification supported, data has been sent
+func SdNotify(state string) (sent bool, err error) {
 	socketAddr := &net.UnixAddr{
 		Name: os.Getenv("NOTIFY_SOCKET"),
 		Net:  "unixgram",
 	}
 
+	// NOTIFY_SOCKET not set
 	if socketAddr.Name == "" {
-		return SdNotifyNoSocket
+		return false, nil
 	}
 
 	conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr)
+	// Error connecting to NOTIFY_SOCKET
 	if err != nil {
-		return err
+		return false, err
 	}
 	defer conn.Close()
 
 	_, err = conn.Write([]byte(state))
-	return err
+	// Error sending the message
+	if err != nil {
+		return false, err
+	}
+	return true, nil
 }

daemon/sdnotify_test.go

@@ -0,0 +1,75 @@
+// Copyright 2016 CoreOS, Inc.
+//
+// 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 daemon
+
+import (
+	"io/ioutil"
+	"net"
+	"os"
+	"testing"
+)
+
+// TestSdNotify
+func TestSdNotify(t *testing.T) {
+	notificationSupportedDataSent := "Notification supported, data sent"
+	notificationSupportedFailure := "Notification supported, but failure happened"
+	notificationNotSupported := "Notification not supported"
+
+	testDir, e := ioutil.TempDir("/tmp/", "test-")
+	if e != nil {
+		panic(e)
+	}
+	defer os.RemoveAll(testDir)
+
+	notifySocket := testDir + "/notify-socket.sock"
+	laddr := net.UnixAddr{
+		Name: notifySocket,
+		Net:  "unixgram",
+	}
+	_, e = net.ListenUnixgram("unixgram", &laddr)
+	if e != nil {
+		panic(e)
+	}
+
+	// (true, nil) - notification supported, data has been sent
+	e = os.Setenv("NOTIFY_SOCKET", notifySocket)
+	if e != nil {
+		panic(e)
+	}
+	sent, err := SdNotify(notificationSupportedDataSent)
+	if !sent || err != nil {
+		t.Errorf("TEST: %s FAILED", notificationSupportedDataSent)
+	}
+
+	// (false, err) - notification supported, but failure happened
+	e = os.Setenv("NOTIFY_SOCKET", testDir+"/not-exist.sock")
+	if e != nil {
+		panic(e)
+	}
+	sent, err = SdNotify(notificationSupportedFailure)
+	if sent && err == nil {
+		t.Errorf("TEST: %s FAILED", notificationSupportedFailure)
+	}
+
+	// (false, nil) - notification not supported
+	e = os.Unsetenv("NOTIFY_SOCKET")
+	if e != nil {
+		panic(e)
+	}
+	sent, err = SdNotify(notificationNotSupported)
+	if sent || err != nil {
+		t.Errorf("TEST: %s FAILED", notificationNotSupported)
+	}
+}

test

@@ -27,7 +27,7 @@ if [ -z "$GOPATH" ]; then
 	go get -u github.com/coreos/pkg/dlopen
 fi
 
-TESTABLE="activation journal login1 machine1 unit"
+TESTABLE="activation daemon journal login1 machine1 unit"
 FORMATTABLE="$TESTABLE sdjournal dbus"
 if [ -e "/run/systemd/system/" ]; then
 	TESTABLE="${TESTABLE} sdjournal"