Move top level packages to internal.

internal/osutil/osutil.go

@@ -0,0 +1,47 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+// Package osutil implements utilities for native OS support.
+package osutil
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"sync"
+)
+
+// Try to keep this entire operation atomic-like. We shouldn't be doing this
+// often enough that there is any contention on this lock.
+var renameLock sync.Mutex
+
+// Rename renames a file, while trying hard to succeed on various systems by
+// temporarily tweaking directory permissions and removing the destination
+// file when necessary. Will make sure to delete the from file if the
+// operation fails, so use only for situations like committing a temp file to
+// it's final location.
+func Rename(from, to string) error {
+	renameLock.Lock()
+	defer renameLock.Unlock()
+
+	// Make sure the destination directory is writeable
+	toDir := filepath.Dir(to)
+	if info, err := os.Stat(toDir); err == nil {
+		os.Chmod(toDir, 0777)
+		defer os.Chmod(toDir, info.Mode())
+	}
+
+	// On Windows, make sure the destination file is writeable (or we can't delete it)
+	if runtime.GOOS == "windows" {
+		os.Chmod(to, 0666)
+		err := os.Remove(to)
+		if err != nil && !os.IsNotExist(err) {
+			return err
+		}
+	}
+
+	// Don't leave a dangling temp file in case of rename error
+	defer os.Remove(from)
+	return os.Rename(from, to)
+}