Fix locktuil on windows

pkg/lockutil/lockutil_test.go

@@ -0,0 +1,56 @@
+package lockutil
+
+import (
+ "errors"
+ "fmt"
+ "os"
+ "path/filepath"
+ "strings"
+ "testing"
+)
+
+const parallel = 20
+
+func TestWithDirLock(t *testing.T) {
+ dir := t.TempDir()
+ log := filepath.Join(dir, "log")
+
+ errc := make(chan error, 10)
+ for i := 0; i < parallel; i++ {
+ go func() {
+ err := WithDirLock(dir, func() error {
+ if _, err := os.Stat(log); err == nil {
+ return nil
+ } else if !errors.Is(err, os.ErrNotExist) {
+ return err
+ }
+ logFile, err := os.OpenFile(log, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o640)
+ if err != nil {
+ return err
+ }
+ defer logFile.Close()
+ if _, err := fmt.Fprintf(logFile, "writer %d\n", i); err != nil {
+ return err
+ }
+ return logFile.Close()
+ })
+ errc <- err
+ }()
+ }
+
+ for i := 0; i < parallel; i++ {
+ err := <-errc
+ if err != nil {
+ t.Error(err)
+ }
+ }
+
+ data, err := os.ReadFile(log)
+ if err != nil {
+ t.Fatal(err)
+ }
+ lines := strings.Split(strings.Trim(string(data), "\n"), "\n")
+ if len(lines) != 1 {
+ t.Errorf("Expected one writer, got %v", lines)
+ }
+}

pkg/lockutil/lockutil_windows.go

@@ -33,20 +33,37 @@ var (
  procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
 )
 
+const (
+ // see https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
+ LOCKFILE_EXCLUSIVE_LOCK = 0x00000002
+ LOCKFILE_FAIL_IMMEDIATELY = 0x00000001
+)
+
 func WithDirLock(dir string, fn func() error) error {
  dirFile, err := os.OpenFile(dir+".lock", os.O_CREATE, 0o644)
  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 {
+ if err := lockFileEx(
+ syscall.Handle(dirFile.Fd()), // hFile
+ LOCKFILE_EXCLUSIVE_LOCK, // dwFlags
+ 0, // dwReserved
+ 1, // nNumberOfBytesToLockLow
+ 0, // nNumberOfBytesToLockHigh
+ &syscall.Overlapped{}, // lpOverlapped
+ ); 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 {
+ if err := unlockFileEx(
+ syscall.Handle(dirFile.Fd()), // hFile
+ 0, // dwReserved
+ 1, // nNumberOfBytesToLockLow
+ 0, // nNumberOfBytesToLockHigh
+ &syscall.Overlapped{}, // lpOverlapped
+ ); err != nil {
  logrus.WithError(err).Errorf("failed to unlock %q", dir)
  }
  }()