git » systemd » commit 7cdf949

diff --git a/systemd.go b/systemd.go
index 4ba1ed4..159b528 100644
--- a/systemd.go
+++ b/systemd.go
@@ -27,6 +27,7 @@ var (
 var files map[string][]*os.File
 var listeners map[string][]net.Listener
 var parseError error
+var listenError error
 var mutex sync.Mutex
 
 // parse files, updating the global state.
@@ -69,13 +70,19 @@ func parse() {
 		return
 	}
 
-	// We should have as many names as we have descriptors.
-	// Note that if we have no descriptors, fdNames will be [""] (due to how
-	// strings.Split works), so we consider that special case.
-	if nfds > 0 && (fdNamesStr == "" || len(fdNames) != nfds) {
-		parseError = fmt.Errorf(
-			"Incorrect LISTEN_FDNAMES, have you set FileDescriptorName?")
-		return
+	// If LISTEN_FDNAMES is set at all, it should have as many names as we
+	// have descriptors. If it isn't set, then we map them all to "".
+	if fdNamesStr == "" {
+		fdNames = []string{}
+		for i := 0; i < nfds; i++ {
+			fdNames = append(fdNames, "")
+		}
+	} else {
+		if nfds > 0 && len(fdNames) != nfds {
+			parseError = fmt.Errorf(
+				"Incorrect LISTEN_FDNAMES, have you set FileDescriptorName?")
+			return
+		}
 	}
 
 	files = map[string][]*os.File{}
@@ -92,12 +99,15 @@ func parse() {
 		f := os.NewFile(uintptr(fd), sysName)
 		files[name] = append(files[name], f)
 
+		// Note this can fail for non-TCP listeners, so we put the error in a
+		// separate variable.
 		lis, err := net.FileListener(f)
 		if err != nil {
-			parseError = fmt.Errorf(
+			listenError = fmt.Errorf(
 				"Error making listener out of fd %d: %v", fd, err)
+		} else {
+			listeners[name] = append(listeners[name], lis)
 		}
-		listeners[name] = append(listeners[name], lis)
 	}
 
 	// Remove them from the environment, to prevent accidental reuse (by
@@ -116,6 +126,9 @@ func parse() {
 // systemd socket unit. Multiple socket units can have the same name, hence
 // the slice of listeners for each name.
 //
+// If the "FileDescriptorName=" option is not used, then all file descriptors
+// are mapped to the "" name.
+//
 // Ideally you should not need to call this more than once. If you do, the
 // same listeners will be returned, as repeated calls to this function will
 // return the same results: the parsing is done only once, and the results are
@@ -125,7 +138,10 @@ func parse() {
 // how the passing works.
 func Listeners() (map[string][]net.Listener, error) {
 	parse()
-	return listeners, parseError
+	if parseError != nil {
+		return listeners, parseError
+	}
+	return listeners, listenError
 }
 
 // OneListener returns a net.Listener for the first systemd socket with the
@@ -142,6 +158,9 @@ func OneListener(name string) (net.Listener, error) {
 	if parseError != nil {
 		return nil, parseError
 	}
+	if listenError != nil {
+		return nil, listenError
+	}
 
 	lis := listeners[name]
 	if len(lis) < 1 {
@@ -185,6 +204,9 @@ func Listen(netw, laddr string) (net.Listener, error) {
 // systemd socket unit. Multiple socket units can have the same name, hence
 // the slice of listeners for each name.
 //
+// If the "FileDescriptorName=" option is not used, then all file descriptors
+// are mapped to the "" name.
+//
 // Ideally you should not need to call this more than once. If you do, the
 // same files will be returned, as repeated calls to this function will return
 // the same results: the parsing is done only once, and the results are saved
diff --git a/systemd_test.go b/systemd_test.go
index e005b67..5e7686d 100644
--- a/systemd_test.go
+++ b/systemd_test.go
@@ -17,6 +17,7 @@ func setenv(pid, fds string, names ...string) {
 	files = nil
 	listeners = nil
 	parseError = nil
+	listenError = nil
 }
 
 func TestEmptyEnvironment(t *testing.T) {
@@ -54,7 +55,6 @@ func TestBadEnvironment(t *testing.T) {
 		{ourPID, "a", []string{"name"}},           // Invalid number of fds.
 		{"1", "1", []string{"name"}},              // PID != ourselves.
 		{ourPID, "1", []string{"name1", "name2"}}, // Too many names.
-		{ourPID, "1", []string{}},                 // Not enough names.
 	}
 	for _, c := range cases {
 		setenv(c.pid, c.fds, c.names...)
@@ -122,9 +122,27 @@ func TestBadFDs(t *testing.T) {
 
 	setenv(strconv.Itoa(os.Getpid()), "1")
 	firstFD = int(f.Fd())
-	if ls, err := Listeners(); len(ls) != 1 || err == nil {
+
+	if ls, err := Listeners(); len(ls) != 0 || err == nil {
 		t.Errorf("Got a non-empty result: %v // %v", ls, err)
 	}
+
+	if l, err := OneListener(""); l != nil || err == nil {
+		t.Errorf("Got a non-empty result: %v // %v", l, err)
+	}
+
+	// It's not a bad FD as far as Files() is concerned.
+	fs, err := Files()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if len(fs) != 1 || len(fs[""]) != 1 {
+		t.Errorf("Unexpected result: %v", fs)
+	}
+	if got := fs[""][0]; got.Fd() != f.Fd() {
+		t.Errorf("File descriptor %d != expected %d (%v)",
+			got.Fd(), f.Fd(), got)
+	}
 }
 
 // newListener creates a TCP listener.
@@ -284,6 +302,29 @@ func TestManySockets(t *testing.T) {
 		os.Getenv("LISTEN_FDNAMES") != "" {
 		t.Errorf("Failed to reset the environment")
 	}
+
+	// Test that things also work with LISTEN_FDNAMES unset.
+	setenv(strconv.Itoa(os.Getpid()), "2")
+	os.Unsetenv("LISTEN_FDNAMES")
+	{
+		lsMap, err := Listeners()
+		if err != nil || len(lsMap) != 1 || len(lsMap[""]) != 2 {
+			t.Fatalf("Got an invalid result: %v // %v", lsMap, err)
+		}
+
+		ls := []net.Listener{
+			lsMap[""][0],
+			lsMap[""][1],
+		}
+
+		for i := 0; i < 2; i++ {
+			if !sameAddr(ls[i].Addr(), expected[i].Addr()) {
+				t.Errorf("Listener %d address mismatch, expected %#v, got %#v",
+					i, ls[i].Addr(), expected[i].Addr())
+			}
+		}
+	}
+
 }
 
 func TestListen(t *testing.T) {