/*
Copyright 2013 The Perkeep 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 fs

import (
	"errors"
	"os/exec"
	"runtime"
	"time"
)

// Unmount attempts to unmount the provided FUSE mount point, forcibly
// if necessary.
func Unmount(point string) error {
	var cmd *exec.Cmd
	switch runtime.GOOS {
	case "darwin":
		cmd = exec.Command("/usr/sbin/diskutil", "umount", "force", point)
	case "linux":
		cmd = exec.Command("fusermount", "-u", point)
	default:
		return errors.New("unmount: unimplemented")
	}

	errc := make(chan error, 1)
	go func() {
		if err := exec.Command("umount", point).Run(); err == nil {
			errc <- err
		}
		// retry to unmount with the fallback cmd
		errc <- cmd.Run()
	}()
	select {
	case <-time.After(1 * time.Second):
		return errors.New("umount timeout")
	case err := <-errc:
		return err
	}
}