host-local: Update host-local IPAM to support Windows

vendor/github.com/alexflint/go-filemutex/filemutex_flock.go

@@ -0,0 +1,67 @@
+// Copyright 2013 The Go 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 filemutex
+
+import (
+	"syscall"
+)
+
+const (
+	mkdirPerm = 0750
+)
+
+// FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
+// This implementation is based on flock syscall.
+type FileMutex struct {
+	fd int
+}
+
+func New(filename string) (*FileMutex, error) {
+	fd, err := syscall.Open(filename, syscall.O_CREAT|syscall.O_RDONLY, mkdirPerm)
+	if err != nil {
+		return nil, err
+	}
+	return &FileMutex{fd: fd}, nil
+}
+
+func (m *FileMutex) Lock() error {
+	if err := syscall.Flock(m.fd, syscall.LOCK_EX); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) Unlock() error {
+	if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) RLock() error {
+	if err := syscall.Flock(m.fd, syscall.LOCK_SH); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) RUnlock() error {
+	if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Close does an Unlock() combined with closing and unlinking the associated
+// lock file. You should create a New() FileMutex for every Lock() attempt if
+// using Close().
+func (m *FileMutex) Close() error {
+	if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
+		return err
+	}
+	return syscall.Close(m.fd)
+}