Add windows version of lockutil from nerdctl

Also include netbsd, next to freebsd + linux

Signed-off-by: Anders F Björklund <[email protected]>

Author: afbjorklund

pkg/lockutil/lockutil.go renamed to pkg/lockutil/lockutil_unix.go

@@ -0,0 +1,70 @@
+// From https://github.com/containerd/nerdctl/blob/v0.13.0/pkg/lockutil/lockutil_windows.go
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package lockutil
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+
+	"github.com/sirupsen/logrus"
+)
+
+// LockFile modified from https://github.com/boltdb/bolt/blob/v1.3.1/bolt_windows.go using MIT
+var (
+	modkernel32      = syscall.NewLazyDLL("kernel32.dll")
+	procLockFileEx   = modkernel32.NewProc("LockFileEx")
+	procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
+)
+
+func WithDirLock(dir string, fn func() error) error {
+	dirFile, err := os.OpenFile(dir+".lock", os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	defer dirFile.Close()
+	// see https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
+	// 1 lock immediately
+	if err := lockFileEx(syscall.Handle(dirFile.Fd()), 1, 0, 1, 0, &syscall.Overlapped{}); err != nil {
+		return fmt.Errorf("failed to lock %q: %w", dir, err)
+	}
+
+	defer func() {
+		if err := unlockFileEx(syscall.Handle(dirFile.Fd()), 0, 1, 0, &syscall.Overlapped{}); err != nil {
+			logrus.WithError(err).Errorf("failed to unlock %q", dir)
+		}
+	}()
+	return fn()
+}
+
+func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
+	r, _, err := procLockFileEx.Call(uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
+	if r == 0 {
+		return err
+	}
+	return nil
+}
+
+func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
+	r, _, err := procUnlockFileEx.Call(uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
+	if r == 0 {
+		return err
+	}
+	return nil
+}