LogDog: Add Butler stream server package.

client/internal/logdog/butler/streamserver/npipe_posix.go

Index: client/internal/logdog/butler/streamserver/npipe_posix.go
diff --git a/client/internal/logdog/butler/streamserver/npipe_posix.go b/client/internal/logdog/butler/streamserver/npipe_posix.go
new file mode 100644
index 0000000000000000000000000000000000000000..204c419fcd5913c6f36cf3e033412912f36860c6
--- /dev/null
+++ b/client/internal/logdog/butler/streamserver/npipe_posix.go
@@ -0,0 +1,91 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd
+
+package streamserver
+
+import (
+	"fmt"
+	"net"
+	"os"
+
+	log "github.com/luci/luci-go/common/logging"
+	"golang.org/x/net/context"
+)
+
+type namedPipeServer struct {
+	namedPipeServerBase
+
+	path string // The path on the filesystem of the UNIX domain named socket
+}
+
+func (s *namedPipeServer) GoString() string {
+	return fmt.Sprintf("namedPipeServer[%s]", s.path)
+}
+
+// Wrapper around the "unix"-type Listener that cleans up the named pipe on
+// creation and 'Close()'
+type selfCleaningUNIXListener struct {
+	path     string
+	listener net.Listener
+}
+
+// NewNamedPipeServer instantiates a new POSIX named pipe server instance.
+func NewNamedPipeServer(ctx context.Context, path string) StreamServer {
+	s := &namedPipeServer{
+		path: path,
+	}
+	s.initBase(ctx)
+	return s
+}
+
+// OS-specific override to create a UNIX named socket listener
+func (s *namedPipeServer) createListener() (net.Listener, error) {
+	log.Fields{
+		"path": s.path,
+	}.Infof(s.ctx, "Creating POSIX server socket Listener.")
+	return newSelfCleaningUNIXListener(s.path)
+}
+
+//
+// selfCleaningUNIXListener
+//
+
+func newSelfCleaningUNIXListener(path string) (net.Listener, error) {
+	// Cleanup any previous entry
+	os.Remove(path)
+
+	// Create a UNIX listener
+	listener, err := net.Listen("unix", path)
+	if err != nil {
+		return nil, err
+	}
+
+	l := selfCleaningUNIXListener{
+		path:     path,
+		listener: listener,
+	}
+	return &l, nil
+}
+
+// Implements net.Listner.Accept
+func (l *selfCleaningUNIXListener) Accept() (c net.Conn, err error) {
+	return l.listener.Accept()
+}
+
+// Implements net.Listener.Close
+func (l *selfCleaningUNIXListener) Close() error {
+	if err := l.listener.Close(); err != nil {
+		return err
+	}
+
+	os.Remove(l.path)
+	return nil
+}
+
+// Implements net.Listener.Addr
+func (l *selfCleaningUNIXListener) Addr() net.Addr {
+	return l.listener.Addr()
+}