netutil: extract socket activation helpers from daemon package.

daemon/daemon.go

@@ -26,14 +26,11 @@ import (
 	"os"
 	"os/exec"
 	"os/signal"
-	"runtime"
 	"strconv"
 	"strings"
 	"sync"
-	unix "syscall"
 	"time"
 
-	"github.com/coreos/go-systemd/activation"
 	"github.com/gorilla/mux"
 	"gopkg.in/tomb.v2"
 
@@ -42,6 +39,7 @@ import (
 	"github.com/snapcore/snapd/httputil"
 	"github.com/snapcore/snapd/i18n"
 	"github.com/snapcore/snapd/logger"
+	"github.com/snapcore/snapd/netutil"
 	"github.com/snapcore/snapd/osutil"
 	"github.com/snapcore/snapd/overlord"
 	"github.com/snapcore/snapd/overlord/auth"
@@ -312,75 +310,22 @@ func logit(handler http.Handler) http.Handler {
 	})
 }
 
-// getListener tries to get a listener for the given socket path from
-// the listener map, and if it fails it tries to set it up directly.
-func getListener(socketPath string, listenerMap map[string]net.Listener) (net.Listener, error) {
-	if listener, ok := listenerMap[socketPath]; ok {
-		return listener, nil
-	}
-
-	if c, err := net.Dial("unix", socketPath); err == nil {
-		c.Close()
-		return nil, fmt.Errorf("socket %q already in use", socketPath)
-	}
-
-	if err := os.Remove(socketPath); err != nil && !os.IsNotExist(err) {
-		return nil, err
-	}
-
-	address, err := net.ResolveUnixAddr("unix", socketPath)
-	if err != nil {
-		return nil, err
-	}
-
-	runtime.LockOSThread()
-	oldmask := unix.Umask(0111)
-	listener, err := net.ListenUnix("unix", address)
-	unix.Umask(oldmask)
-	runtime.UnlockOSThread()
-	if err != nil {
-		return nil, err
-	}
-
-	logger.Debugf("socket %q was not activated; listening", socketPath)
-
-	return listener, nil
-}
-
-// activationListeners builds a map of addresses to listeners that were passed
-// during systemd activation
-func activationListeners() (lns map[string]net.Listener, err error) {
-	// pass false to keep LISTEN_* environment variables passed by systemd
-	files := activation.Files(false)
-	lns = make(map[string]net.Listener, len(files))
-
-	for _, f := range files {
-		ln, err := net.FileListener(f)
-		if err != nil {
-			return nil, err
-		}
-		addr := ln.Addr().String()
-		lns[addr] = ln
-	}
-	return lns, nil
-}
-
 // Init sets up the Daemon's internal workings.
 // Don't call more than once.
 func (d *Daemon) Init() error {
-	listenerMap, err := activationListeners()
+	listenerMap, err := netutil.ActivationListeners()
 	if err != nil {
 		return err
 	}
 
 	// The SnapdSocket is required-- without it, die.
-	if listener, err := getListener(dirs.SnapdSocket, listenerMap); err == nil {
+	if listener, err := netutil.GetListener(dirs.SnapdSocket, listenerMap); err == nil {
 		d.snapdListener = &ucrednetListener{listener}
 	} else {
 		return fmt.Errorf("when trying to listen on %s: %v", dirs.SnapdSocket, err)
 	}
 
-	if listener, err := getListener(dirs.SnapSocket, listenerMap); err == nil {
+	if listener, err := netutil.GetListener(dirs.SnapSocket, listenerMap); err == nil {
 		// This listener may also be nil if that socket wasn't among
 		// the listeners, so check it before using it.
 		d.snapListener = &ucrednetListener{listener}

netutil/activation.go

@@ -0,0 +1,85 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2015-2019 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package netutil
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"runtime"
+	unix "syscall"
+
+	"github.com/coreos/go-systemd/activation"
+
+	"github.com/snapcore/snapd/logger"
+)
+
+// GetListener tries to get a listener for the given socket path from
+// the listener map, and if it fails it tries to set it up directly.
+func GetListener(socketPath string, listenerMap map[string]net.Listener) (net.Listener, error) {
+	if listener, ok := listenerMap[socketPath]; ok {
+		return listener, nil
+	}
+
+	if c, err := net.Dial("unix", socketPath); err == nil {
+		c.Close()
+		return nil, fmt.Errorf("socket %q already in use", socketPath)
+	}
+
+	if err := os.Remove(socketPath); err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+
+	address, err := net.ResolveUnixAddr("unix", socketPath)
+	if err != nil {
+		return nil, err
+	}
+
+	runtime.LockOSThread()
+	oldmask := unix.Umask(0111)
+	listener, err := net.ListenUnix("unix", address)
+	unix.Umask(oldmask)
+	runtime.UnlockOSThread()
+	if err != nil {
+		return nil, err
+	}
+
+	logger.Debugf("socket %q was not activated; listening", socketPath)
+
+	return listener, nil
+}
+
+// ActivationListeners builds a map of addresses to listeners that were passed
+// during systemd activation
+func ActivationListeners() (lns map[string]net.Listener, err error) {
+	// pass false to keep LISTEN_* environment variables passed by systemd
+	files := activation.Files(false)
+	lns = make(map[string]net.Listener, len(files))
+
+	for _, f := range files {
+		ln, err := net.FileListener(f)
+		if err != nil {
+			return nil, err
+		}
+		addr := ln.Addr().String()
+		lns[addr] = ln
+	}
+	return lns, nil
+}