Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/src/os/file_mutex_plan9.go b/src/os/file_mutex_plan9.go
new file mode 100644
index 0000000..26bf5a7
--- /dev/null
+++ b/src/os/file_mutex_plan9.go
@@ -0,0 +1,70 @@
+// Copyright 2022 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 os
+
+// File locking support for Plan 9. This uses fdMutex from the
+// internal/poll package.
+
+// incref adds a reference to the file. It returns an error if the file
+// is already closed. This method is on File so that we can incorporate
+// a nil test.
+func (f *File) incref(op string) (err error) {
+	if f == nil {
+		return ErrInvalid
+	}
+	if !f.fdmu.Incref() {
+		err = ErrClosed
+		if op != "" {
+			err = &PathError{Op: op, Path: f.name, Err: err}
+		}
+	}
+	return err
+}
+
+// decref removes a reference to the file. If this is the last
+// remaining reference, and the file has been marked to be closed,
+// then actually close it.
+func (file *file) decref() error {
+	if file.fdmu.Decref() {
+		return file.destroy()
+	}
+	return nil
+}
+
+// readLock adds a reference to the file and locks it for reading.
+// It returns an error if the file is already closed.
+func (file *file) readLock() error {
+	if !file.fdmu.ReadLock() {
+		return ErrClosed
+	}
+	return nil
+}
+
+// readUnlock removes a reference from the file and unlocks it for reading.
+// It also closes the file if it marked as closed and there is no remaining
+// reference.
+func (file *file) readUnlock() {
+	if file.fdmu.ReadUnlock() {
+		file.destroy()
+	}
+}
+
+// writeLock adds a reference to the file and locks it for writing.
+// It returns an error if the file is already closed.
+func (file *file) writeLock() error {
+	if !file.fdmu.WriteLock() {
+		return ErrClosed
+	}
+	return nil
+}
+
+// writeUnlock removes a reference from the file and unlocks it for writing.
+// It also closes the file if it is marked as closed and there is no remaining
+// reference.
+func (file *file) writeUnlock() {
+	if file.fdmu.WriteUnlock() {
+		file.destroy()
+	}
+}