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// Copyright 2015 Google Inc. All Rights Reserved.
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// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
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package fuse
import (
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bazilfuse "bazil.org/fuse"
// A struct representing the status of a mount operation, with methods for
// waiting on the mount to complete, waiting for unmounting, and causing
// unmounting.
type MountedFileSystem struct {
dir string
// The result to return from WaitForReady. Not valid until the channel is
// closed.
readyStatus error
readyStatusAvailable chan struct{}
// The result to return from Join. Not valid until the channel is closed.
joinStatus error
joinStatusAvailable chan struct{}
// Return the directory on which the file system is mounted (or where we
// attempted to mount it.)
func (mfs *MountedFileSystem) Dir() string {
return mfs.dir
// Wait until the mount point is ready to be used. After a successful return
// from this function, the contents of the mounted file system should be
// visible in the directory supplied to NewMountPoint. May be called multiple
// times.
func (mfs *MountedFileSystem) WaitForReady(ctx context.Context) error {
select {
case <-mfs.readyStatusAvailable:
return mfs.readyStatus
case <-ctx.Done():
return ctx.Err()
// Block until a mounted file system has been unmounted. The return value will
// be non-nil if anything unexpected happened while serving. May be called
// multiple times. Must not be called unless WaitForReady has returned nil.
func (mfs *MountedFileSystem) Join(ctx context.Context) error {
select {
case <-mfs.joinStatusAvailable:
return mfs.joinStatus
case <-ctx.Done():
return ctx.Err()
// Attempt to unmount the file system. Use Join to wait for it to actually be
// unmounted. You must first call WaitForReady to ensure there is no race with
// mounting.
func (mfs *MountedFileSystem) Unmount() error {
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return bazilfuse.Unmount(mfs.dir)
// Runs in the background.
func (mfs *MountedFileSystem) mountAndServe(
server *server,
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options []bazilfuse.MountOption) {
logger := getLogger()
// Open a FUSE connection.
logger.Println("Opening a FUSE connection.")
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c, err := bazilfuse.Mount(mfs.dir, options...)
if err != nil {
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mfs.readyStatus = errors.New("bazilfuse.Mount: " + err.Error())
defer c.Close()
// Start a goroutine that will notify the MountedFileSystem object when the
// connection says it is ready (or it fails to become ready).
go func() {
logger.Println("Waiting for the FUSE connection to be ready.")
logger.Println("The FUSE connection is ready.")
mfs.readyStatus = c.MountError
// Serve the connection using the file system object.
logger.Println("Serving the FUSE connection.")
if err := server.Serve(c); err != nil {
mfs.joinStatus = errors.New("Serve: " + err.Error())
// Signal that everything is okay.
// Attempt to mount the supplied file system on the given directory.
// mfs.WaitForReady() must be called to find out whether the mount was
// successful.
func Mount(
dir string,
fs FileSystem,
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options ...bazilfuse.MountOption) (mfs *MountedFileSystem, err error) {
// Create a server object.
server, err := newServer(fs)
if err != nil {
// Initialize the struct.
mfs = &MountedFileSystem{
dir: dir,
readyStatusAvailable: make(chan struct{}),
joinStatusAvailable: make(chan struct{}),
// Mount in the background.
go mfs.mountAndServe(server, options)