f7d9b15707
Before this change cgofuse and libatexit would race to see who could unmount the file system with unpredicatable results. On Linux it could report an error or not, depending. This change checks to see if umount is beng called from a signal and if so leaves the unmounting to cgofuse/libfuse. See #4804
237 lines
6.2 KiB
Go
237 lines
6.2 KiB
Go
// Package cmount implements a FUSE mounting system for rclone remotes.
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//
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// This uses the cgo based cgofuse library
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// +build cmount
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// +build cgo
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// +build linux darwin freebsd windows
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package cmount
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import (
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"fmt"
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"os"
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"runtime"
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"strings"
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"time"
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"github.com/billziss-gh/cgofuse/fuse"
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"github.com/pkg/errors"
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"github.com/rclone/rclone/cmd/mountlib"
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"github.com/rclone/rclone/fs"
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"github.com/rclone/rclone/lib/atexit"
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"github.com/rclone/rclone/vfs"
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)
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func init() {
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name := "cmount"
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cmountOnly := runtime.GOOS == "windows" || runtime.GOOS == "darwin"
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if cmountOnly {
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name = "mount"
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}
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cmd := mountlib.NewMountCommand(name, false, mount)
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if cmountOnly {
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cmd.Aliases = append(cmd.Aliases, "cmount")
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}
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mountlib.AddRc("cmount", mount)
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}
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// mountOptions configures the options from the command line flags
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func mountOptions(VFS *vfs.VFS, device string, mountpoint string, opt *mountlib.Options) (options []string) {
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// Options
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options = []string{
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"-o", "fsname=" + device,
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"-o", "subtype=rclone",
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"-o", fmt.Sprintf("max_readahead=%d", opt.MaxReadAhead),
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"-o", fmt.Sprintf("attr_timeout=%g", opt.AttrTimeout.Seconds()),
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// This causes FUSE to supply O_TRUNC with the Open
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// call which is more efficient for cmount. However
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// it does not work with cgofuse on Windows with
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// WinFSP so cmount must work with or without it.
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"-o", "atomic_o_trunc",
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}
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if opt.DebugFUSE {
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options = append(options, "-o", "debug")
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}
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// OSX options
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if runtime.GOOS == "darwin" {
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if opt.NoAppleDouble {
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options = append(options, "-o", "noappledouble")
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}
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if opt.NoAppleXattr {
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options = append(options, "-o", "noapplexattr")
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}
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}
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// determine if ExtraOptions already has an opt in
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hasOption := func(optionName string) bool {
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optionName += "="
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for _, option := range opt.ExtraOptions {
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if strings.HasPrefix(option, optionName) {
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return true
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}
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}
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return false
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}
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// Windows options
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if runtime.GOOS == "windows" {
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// These cause WinFsp to mean the current user
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if !hasOption("uid") {
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options = append(options, "-o", "uid=-1")
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}
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if !hasOption("gid") {
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options = append(options, "-o", "gid=-1")
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}
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options = append(options, "--FileSystemName=rclone")
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}
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if runtime.GOOS == "darwin" || runtime.GOOS == "windows" {
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if opt.VolumeName != "" {
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options = append(options, "-o", "volname="+opt.VolumeName)
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}
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}
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if opt.AllowNonEmpty {
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options = append(options, "-o", "nonempty")
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}
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if opt.AllowOther {
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options = append(options, "-o", "allow_other")
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}
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if opt.AllowRoot {
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options = append(options, "-o", "allow_root")
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}
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if opt.DefaultPermissions {
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options = append(options, "-o", "default_permissions")
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}
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if VFS.Opt.ReadOnly {
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options = append(options, "-o", "ro")
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}
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if opt.WritebackCache {
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// FIXME? options = append(options, "-o", WritebackCache())
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}
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if opt.DaemonTimeout != 0 {
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options = append(options, "-o", fmt.Sprintf("daemon_timeout=%d", int(opt.DaemonTimeout.Seconds())))
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}
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for _, option := range opt.ExtraOptions {
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options = append(options, "-o", option)
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}
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for _, option := range opt.ExtraFlags {
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options = append(options, option)
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}
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return options
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}
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// waitFor runs fn() until it returns true or the timeout expires
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func waitFor(fn func() bool) (ok bool) {
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const totalWait = 10 * time.Second
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const individualWait = 10 * time.Millisecond
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for i := 0; i < int(totalWait/individualWait); i++ {
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ok = fn()
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if ok {
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return ok
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}
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time.Sleep(individualWait)
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}
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return false
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}
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// mount the file system
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//
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// The mount point will be ready when this returns.
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//
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// returns an error, and an error channel for the serve process to
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// report an error when fusermount is called.
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func mount(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (<-chan error, func() error, error) {
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f := VFS.Fs()
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fs.Debugf(f, "Mounting on %q", mountpoint)
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// Check the mountpoint - in Windows the mountpoint mustn't exist before the mount
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if runtime.GOOS != "windows" {
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fi, err := os.Stat(mountpoint)
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if err != nil {
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return nil, nil, errors.Wrap(err, "mountpoint")
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}
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if !fi.IsDir() {
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return nil, nil, errors.New("mountpoint is not a directory")
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}
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}
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// Create underlying FS
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fsys := NewFS(VFS)
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host := fuse.NewFileSystemHost(fsys)
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host.SetCapReaddirPlus(true) // only works on Windows
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host.SetCapCaseInsensitive(f.Features().CaseInsensitive)
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// Create options
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options := mountOptions(VFS, f.Name()+":"+f.Root(), mountpoint, opt)
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fs.Debugf(f, "Mounting with options: %q", options)
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// Serve the mount point in the background returning error to errChan
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errChan := make(chan error, 1)
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go func() {
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defer func() {
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if r := recover(); r != nil {
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errChan <- errors.Errorf("mount failed: %v", r)
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}
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}()
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var err error
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ok := host.Mount(mountpoint, options)
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if !ok {
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err = errors.New("mount failed")
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fs.Errorf(f, "Mount failed")
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}
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errChan <- err
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}()
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// unmount
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unmount := func() error {
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// Shutdown the VFS
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fsys.VFS.Shutdown()
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var umountOK bool
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if atexit.Signalled() {
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// If we have received a signal then FUSE will be shutting down already
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fs.Debugf(nil, "Not calling host.Unmount as signal received")
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umountOK = true
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} else {
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fs.Debugf(nil, "Calling host.Unmount")
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umountOK = host.Unmount()
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}
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if umountOK {
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fs.Debugf(nil, "Unmounted successfully")
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if runtime.GOOS == "windows" {
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if !waitFor(func() bool {
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_, err := os.Stat(mountpoint)
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return err != nil
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}) {
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fs.Errorf(nil, "mountpoint %q didn't disappear after unmount - continuing anyway", mountpoint)
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}
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}
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return nil
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}
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fs.Debugf(nil, "host.Unmount failed")
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return errors.New("host unmount failed")
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}
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// Wait for the filesystem to become ready, checking the file
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// system didn't blow up before starting
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select {
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case err := <-errChan:
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err = errors.Wrap(err, "mount stopped before calling Init")
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return nil, nil, err
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case <-fsys.ready:
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}
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// Wait for the mount point to be available on Windows
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// On Windows the Init signal comes slightly before the mount is ready
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if runtime.GOOS == "windows" {
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if !waitFor(func() bool {
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_, err := os.Stat(mountpoint)
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return err == nil
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}) {
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fs.Errorf(nil, "mountpoint %q didn't became available on mount - continuing anyway", mountpoint)
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}
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}
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return errChan, unmount, nil
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}
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