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

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

@@ -0,0 +1,102 @@
+// 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.
+
+package filemutex
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+var (
+	modkernel32      = syscall.NewLazyDLL("kernel32.dll")
+	procLockFileEx   = modkernel32.NewProc("LockFileEx")
+	procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
+)
+
+const (
+	lockfileExclusiveLock = 2
+)
+
+func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
+	r1, _, e1 := syscall.Syscall6(procLockFileEx.Addr(), 6, uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
+	r1, _, e1 := syscall.Syscall6(procUnlockFileEx.Addr(), 5, uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}
+
+// FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
+// This implementation is based on flock syscall.
+type FileMutex struct {
+	fd syscall.Handle
+}
+
+func New(filename string) (*FileMutex, error) {
+	fd, err := syscall.CreateFile(&(syscall.StringToUTF16(filename)[0]), syscall.GENERIC_READ|syscall.GENERIC_WRITE,
+		syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE, nil, syscall.OPEN_ALWAYS, syscall.FILE_ATTRIBUTE_NORMAL, 0)
+	if err != nil {
+		return nil, err
+	}
+	return &FileMutex{fd: fd}, nil
+}
+
+func (m *FileMutex) Lock() error {
+	var ol syscall.Overlapped
+	if err := lockFileEx(m.fd, lockfileExclusiveLock, 0, 1, 0, &ol); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) Unlock() error {
+	var ol syscall.Overlapped
+	if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) RLock() error {
+	var ol syscall.Overlapped
+	if err := lockFileEx(m.fd, 0, 0, 1, 0, &ol); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (m *FileMutex) RUnlock() error {
+	var ol syscall.Overlapped
+	if err := unlockFileEx(m.fd, 0, 1, 0, &ol); 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 {
+	var ol syscall.Overlapped
+	if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
+		return err
+	}
+	return syscall.Close(m.fd)
+}