Support OSXFUSE 3.x, fall back to 2.x if needed

Also supports custom bundled OSXFUSE installs.

mount_config.go

@@ -135,6 +135,14 @@ type MountConfig struct {
 	// default name involving the string 'osxfuse' is used.
 	VolumeName string
 
+	// OS X only.
+	//
+	// OSXFUSELocations sets where to look for OSXFUSE files. The arguments are
+	// all the possible locations. The previous locations are replaced.
+	//
+	// Without this option, OSXFUSELocationV3 and OSXFUSELocationV2 are used.
+	OSXFUSELocations []OSXFUSEPaths
+
 	// Additional key=value options to pass unadulterated to the underlying mount
 	// command. See `man 8 mount`, the fuse documentation, etc. for
 	// system-specific information.
@@ -230,3 +238,38 @@ func (c *MountConfig) toOptionsString() string {
 
 	return strings.Join(components, ",")
 }
+
+// OSXFUSEPaths describes the paths used by an installed OSXFUSE version.
+// See OSXFUSELocationV3 for typical values.
+type OSXFUSEPaths struct {
+	// Prefix for the device file. At mount time, an incrementing number is
+	// suffixed until a free FUSE device is found.
+	DevicePrefix string
+
+	// Path of the load helper, used to load the kernel extension if no device
+	// files are found.
+	Load string
+
+	// Path of the mount helper, used for the actual mount operation.
+	Mount string
+
+	// Environment variable used to pass the path to the executable calling the
+	// mount helper.
+	DaemonVar string
+}
+
+// Default paths for OSXFUSE. See OSXFUSELocations.
+var (
+	OSXFUSELocationV3 = OSXFUSEPaths{
+		DevicePrefix: "/dev/osxfuse",
+		Load:         "/Library/Filesystems/osxfuse.fs/Contents/Resources/load_osxfuse",
+		Mount:        "/Library/Filesystems/osxfuse.fs/Contents/Resources/mount_osxfuse",
+		DaemonVar:    "MOUNT_OSXFUSE_DAEMON_PATH",
+	}
+	OSXFUSELocationV2 = OSXFUSEPaths{
+		DevicePrefix: "/dev/osxfuse",
+		Load:         "/Library/Filesystems/osxfusefs.fs/Support/load_osxfusefs",
+		Mount:        "/Library/Filesystems/osxfusefs.fs/Support/mount_osxfusefs",
+		DaemonVar:    "MOUNT_FUSEFS_DAEMON_PATH",
+	}
+)

mount_darwin.go

@@ -14,10 +14,16 @@ import (
 )
 
 var errNoAvail = errors.New("no available fuse devices")
-var errNotLoaded = errors.New("osxfusefs is not loaded")
+var errNotLoaded = errors.New("osxfuse is not loaded")
 
-func loadOSXFUSE() error {
-	cmd := exec.Command("/Library/Filesystems/osxfusefs.fs/Support/load_osxfusefs")
+// errOSXFUSENotFound is returned from Mount when the OSXFUSE installation is
+// not detected.
+//
+// Make sure OSXFUSE is installed, or see OSXFUSELocations for customization.
+var errOSXFUSENotFound = errors.New("cannot locate OSXFUSE")
+
+func loadOSXFUSE(bin string) error {
+	cmd := exec.Command(bin)
 	cmd.Dir = "/"
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
@@ -25,10 +31,10 @@ func loadOSXFUSE() error {
 	return err
 }
 
-func openOSXFUSEDev() (dev *os.File, err error) {
+func openOSXFUSEDev(devPrefix string) (dev *os.File, err error) {
 	// Try each device name.
 	for i := uint64(0); ; i++ {
-		path := fmt.Sprintf("/dev/osxfuse%d", i)
+		path := devPrefix + strconv.FormatUint(i, 10)
 		dev, err = os.OpenFile(path, os.O_RDWR, 0000)
 		if os.IsNotExist(err) {
 			if i == 0 {
@@ -52,11 +58,12 @@ func openOSXFUSEDev() (dev *os.File, err error) {
 }
 
 func callMount(
+	bin string,
+	daemonVar string,
 	dir string,
 	cfg *MountConfig,
 	dev *os.File,
 	ready chan<- error) (err error) {
-	const bin = "/Library/Filesystems/osxfusefs.fs/Support/mount_osxfusefs"
 
 	// The mount helper doesn't understand any escaping.
 	for k, v := range cfg.toMap() {
@@ -85,8 +92,15 @@ func callMount(
 	)
 	cmd.ExtraFiles = []*os.File{dev}
 	cmd.Env = os.Environ()
+	// OSXFUSE <3.3.0
 	cmd.Env = append(cmd.Env, "MOUNT_FUSEFS_CALL_BY_LIB=")
-	cmd.Env = append(cmd.Env, "MOUNT_FUSEFS_DAEMON_PATH="+bin)
+	// OSXFUSE >=3.3.0
+	cmd.Env = append(cmd.Env, "MOUNT_OSXFUSE_CALL_BY_LIB=")
+
+	daemon := os.Args[0]
+	if daemonVar != "" {
+		cmd.Env = append(cmd.Env, daemonVar+"="+daemon)
+	}
 
 	var buf bytes.Buffer
 	cmd.Stdout = &buf
@@ -122,19 +136,34 @@ func mount(
 	dir string,
 	cfg *MountConfig,
 	ready chan<- error) (dev *os.File, err error) {
+	// get OSXFUSE locations
+	locations := cfg.OSXFUSELocations
+	if locations == nil {
+		locations = []OSXFUSEPaths{
+			OSXFUSELocationV3,
+			OSXFUSELocationV2,
+		}
+	}
+
+	for _, loc := range locations {
+		if _, err := os.Stat(loc.Mount); os.IsNotExist(err) {
+			// try the other locations
+			continue
+		}
+
 		// Open the device.
-	dev, err = openOSXFUSEDev()
+		dev, err = openOSXFUSEDev(loc.DevicePrefix)
 
-	// Special case: we may need to explicitly load osxfuse. Load it, then try
-	// again.
+		// Special case: we may need to explicitly load osxfuse. Load it, then
+		// try again.
 		if err == errNotLoaded {
-		err = loadOSXFUSE()
+			err = loadOSXFUSE(loc.Load)
 			if err != nil {
 				err = fmt.Errorf("loadOSXFUSE: %v", err)
 				return
 			}
 
-		dev, err = openOSXFUSEDev()
+			dev, err = openOSXFUSEDev(loc.DevicePrefix)
 		}
 
 		// Propagate errors.
@@ -144,12 +173,16 @@ func mount(
 		}
 
 		// Call the mount binary with the device.
-	err = callMount(dir, cfg, dev, ready)
+		err = callMount(loc.Mount, loc.DaemonVar, dir, cfg, dev, ready)
 		if err != nil {
 			dev.Close()
 			err = fmt.Errorf("callMount: %v", err)
 			return
 		}
 
+		return
+	}
+
+	err = errOSXFUSENotFound
 	return
 }