swarm/api: support mounting manifests via FUSE (#3690)

2 files changed, 1667 insertions, 0 deletions

diff --git a/vendor/bazil.org/fuse/fs/serve.go b/vendor/bazil.org/fuse/fs/serve.go
new file mode 100644
index 000000000..e9fc56590
--- /dev/null
+++ b/vendor/bazil.org/fuse/fs/serve.go
@@ -0,0 +1,1568 @@
+// FUSE service loop, for servers that wish to use it.
+
+package fs // import "bazil.org/fuse/fs"
+
+import (
+	"encoding/binary"
+	"fmt"
+	"hash/fnv"
+	"io"
+	"log"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/net/context"
+)
+
+import (
+	"bytes"
+
+	"bazil.org/fuse"
+	"bazil.org/fuse/fuseutil"
+)
+
+const (
+	attrValidTime  = 1 * time.Minute
+	entryValidTime = 1 * time.Minute
+)
+
+// TODO: FINISH DOCS
+
+// An FS is the interface required of a file system.
+//
+// Other FUSE requests can be handled by implementing methods from the
+// FS* interfaces, for example FSStatfser.
+type FS interface {
+	// Root is called to obtain the Node for the file system root.
+	Root() (Node, error)
+}
+
+type FSStatfser interface {
+	// Statfs is called to obtain file system metadata.
+	// It should write that data to resp.
+	Statfs(ctx context.Context, req *fuse.StatfsRequest, resp *fuse.StatfsResponse) error
+}
+
+type FSDestroyer interface {
+	// Destroy is called when the file system is shutting down.
+	//
+	// Linux only sends this request for block device backed (fuseblk)
+	// filesystems, to allow them to flush writes to disk before the
+	// unmount completes.
+	Destroy()
+}
+
+type FSInodeGenerator interface {
+	// GenerateInode is called to pick a dynamic inode number when it
+	// would otherwise be 0.
+	//
+	// Not all filesystems bother tracking inodes, but FUSE requires
+	// the inode to be set, and fewer duplicates in general makes UNIX
+	// tools work better.
+	//
+	// Operations where the nodes may return 0 inodes include Getattr,
+	// Setattr and ReadDir.
+	//
+	// If FS does not implement FSInodeGenerator, GenerateDynamicInode
+	// is used.
+	//
+	// Implementing this is useful to e.g. constrain the range of
+	// inode values used for dynamic inodes.
+	GenerateInode(parentInode uint64, name string) uint64
+}
+
+// A Node is the interface required of a file or directory.
+// See the documentation for type FS for general information
+// pertaining to all methods.
+//
+// A Node must be usable as a map key, that is, it cannot be a
+// function, map or slice.
+//
+// Other FUSE requests can be handled by implementing methods from the
+// Node* interfaces, for example NodeOpener.
+//
+// Methods returning Node should take care to return the same Node
+// when the result is logically the same instance. Without this, each
+// Node will get a new NodeID, causing spurious cache invalidations,
+// extra lookups and aliasing anomalies. This may not matter for a
+// simple, read-only filesystem.
+type Node interface {
+	// Attr fills attr with the standard metadata for the node.
+	//
+	// Fields with reasonable defaults are prepopulated. For example,
+	// all times are set to a fixed moment when the program started.
+	//
+	// If Inode is left as 0, a dynamic inode number is chosen.
+	//
+	// The result may be cached for the duration set in Valid.
+	Attr(ctx context.Context, attr *fuse.Attr) error
+}
+
+type NodeGetattrer interface {
+	// Getattr obtains the standard metadata for the receiver.
+	// It should store that metadata in resp.
+	//
+	// If this method is not implemented, the attributes will be
+	// generated based on Attr(), with zero values filled in.
+	Getattr(ctx context.Context, req *fuse.GetattrRequest, resp *fuse.GetattrResponse) error
+}
+
+type NodeSetattrer interface {
+	// Setattr sets the standard metadata for the receiver.
+	//
+	// Note, this is also used to communicate changes in the size of
+	// the file, outside of Writes.
+	//
+	// req.Valid is a bitmask of what fields are actually being set.
+	// For example, the method should not change the mode of the file
+	// unless req.Valid.Mode() is true.
+	Setattr(ctx context.Context, req *fuse.SetattrRequest, resp *fuse.SetattrResponse) error
+}
+
+type NodeSymlinker interface {
+	// Symlink creates a new symbolic link in the receiver, which must be a directory.
+	//
+	// TODO is the above true about directories?
+	Symlink(ctx context.Context, req *fuse.SymlinkRequest) (Node, error)
+}
+
+// This optional request will be called only for symbolic link nodes.
+type NodeReadlinker interface {
+	// Readlink reads a symbolic link.
+	Readlink(ctx context.Context, req *fuse.ReadlinkRequest) (string, error)
+}
+
+type NodeLinker interface {
+	// Link creates a new directory entry in the receiver based on an
+	// existing Node. Receiver must be a directory.
+	Link(ctx context.Context, req *fuse.LinkRequest, old Node) (Node, error)
+}
+
+type NodeRemover interface {
+	// Remove removes the entry with the given name from
+	// the receiver, which must be a directory.  The entry to be removed
+	// may correspond to a file (unlink) or to a directory (rmdir).
+	Remove(ctx context.Context, req *fuse.RemoveRequest) error
+}
+
+type NodeAccesser interface {
+	// Access checks whether the calling context has permission for
+	// the given operations on the receiver. If so, Access should
+	// return nil. If not, Access should return EPERM.
+	//
+	// Note that this call affects the result of the access(2) system
+	// call but not the open(2) system call. If Access is not
+	// implemented, the Node behaves as if it always returns nil
+	// (permission granted), relying on checks in Open instead.
+	Access(ctx context.Context, req *fuse.AccessRequest) error
+}
+
+type NodeStringLookuper interface {
+	// Lookup looks up a specific entry in the receiver,
+	// which must be a directory.  Lookup should return a Node
+	// corresponding to the entry.  If the name does not exist in
+	// the directory, Lookup should return ENOENT.
+	//
+	// Lookup need not to handle the names "." and "..".
+	Lookup(ctx context.Context, name string) (Node, error)
+}
+
+type NodeRequestLookuper interface {
+	// Lookup looks up a specific entry in the receiver.
+	// See NodeStringLookuper for more.
+	Lookup(ctx context.Context, req *fuse.LookupRequest, resp *fuse.LookupResponse) (Node, error)
+}
+
+type NodeMkdirer interface {
+	Mkdir(ctx context.Context, req *fuse.MkdirRequest) (Node, error)
+}
+
+type NodeOpener interface {
+	// Open opens the receiver. After a successful open, a client
+	// process has a file descriptor referring to this Handle.
+	//
+	// Open can also be also called on non-files. For example,
+	// directories are Opened for ReadDir or fchdir(2).
+	//
+	// If this method is not implemented, the open will always
+	// succeed, and the Node itself will be used as the Handle.
+	//
+	// XXX note about access.  XXX OpenFlags.
+	Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (Handle, error)
+}
+
+type NodeCreater interface {
+	// Create creates a new directory entry in the receiver, which
+	// must be a directory.
+	Create(ctx context.Context, req *fuse.CreateRequest, resp *fuse.CreateResponse) (Node, Handle, error)
+}
+
+type NodeForgetter interface {
+	// Forget about this node. This node will not receive further
+	// method calls.
+	//
+	// Forget is not necessarily seen on unmount, as all nodes are
+	// implicitly forgotten as part part of the unmount.
+	Forget()
+}
+
+type NodeRenamer interface {
+	Rename(ctx context.Context, req *fuse.RenameRequest, newDir Node) error
+}
+
+type NodeMknoder interface {
+	Mknod(ctx context.Context, req *fuse.MknodRequest) (Node, error)
+}
+
+// TODO this should be on Handle not Node
+type NodeFsyncer interface {
+	Fsync(ctx context.Context, req *fuse.FsyncRequest) error
+}
+
+type NodeGetxattrer interface {
+	// Getxattr gets an extended attribute by the given name from the
+	// node.
+	//
+	// If there is no xattr by that name, returns fuse.ErrNoXattr.
+	Getxattr(ctx context.Context, req *fuse.GetxattrRequest, resp *fuse.GetxattrResponse) error
+}
+
+type NodeListxattrer interface {
+	// Listxattr lists the extended attributes recorded for the node.
+	Listxattr(ctx context.Context, req *fuse.ListxattrRequest, resp *fuse.ListxattrResponse) error
+}
+
+type NodeSetxattrer interface {
+	// Setxattr sets an extended attribute with the given name and
+	// value for the node.
+	Setxattr(ctx context.Context, req *fuse.SetxattrRequest) error
+}
+
+type NodeRemovexattrer interface {
+	// Removexattr removes an extended attribute for the name.
+	//
+	// If there is no xattr by that name, returns fuse.ErrNoXattr.
+	Removexattr(ctx context.Context, req *fuse.RemovexattrRequest) error
+}
+
+var startTime = time.Now()
+
+func nodeAttr(ctx context.Context, n Node, attr *fuse.Attr) error {
+	attr.Valid = attrValidTime
+	attr.Nlink = 1
+	attr.Atime = startTime
+	attr.Mtime = startTime
+	attr.Ctime = startTime
+	attr.Crtime = startTime
+	if err := n.Attr(ctx, attr); err != nil {
+		return err
+	}
+	return nil
+}
+
+// A Handle is the interface required of an opened file or directory.
+// See the documentation for type FS for general information
+// pertaining to all methods.
+//
+// Other FUSE requests can be handled by implementing methods from the
+// Handle* interfaces. The most common to implement are HandleReader,
+// HandleReadDirer, and HandleWriter.
+//
+// TODO implement methods: Getlk, Setlk, Setlkw
+type Handle interface {
+}
+
+type HandleFlusher interface {
+	// Flush is called each time the file or directory is closed.
+	// Because there can be multiple file descriptors referring to a
+	// single opened file, Flush can be called multiple times.
+	Flush(ctx context.Context, req *fuse.FlushRequest) error
+}
+
+type HandleReadAller interface {
+	ReadAll(ctx context.Context) ([]byte, error)
+}
+
+type HandleReadDirAller interface {
+	ReadDirAll(ctx context.Context) ([]fuse.Dirent, error)
+}
+
+type HandleReader interface {
+	// Read requests to read data from the handle.
+	//
+	// There is a page cache in the kernel that normally submits only
+	// page-aligned reads spanning one or more pages. However, you
+	// should not rely on this. To see individual requests as
+	// submitted by the file system clients, set OpenDirectIO.
+	//
+	// Note that reads beyond the size of the file as reported by Attr
+	// are not even attempted (except in OpenDirectIO mode).
+	Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error
+}
+
+type HandleWriter interface {
+	// Write requests to write data into the handle at the given offset.
+	// Store the amount of data written in resp.Size.
+	//
+	// There is a writeback page cache in the kernel that normally submits
+	// only page-aligned writes spanning one or more pages. However,
+	// you should not rely on this. To see individual requests as
+	// submitted by the file system clients, set OpenDirectIO.
+	//
+	// Writes that grow the file are expected to update the file size
+	// (as seen through Attr). Note that file size changes are
+	// communicated also through Setattr.
+	Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse) error
+}
+
+type HandleReleaser interface {
+	Release(ctx context.Context, req *fuse.ReleaseRequest) error
+}
+
+type Config struct {
+	// Function to send debug log messages to. If nil, use fuse.Debug.
+	// Note that changing this or fuse.Debug may not affect existing
+	// calls to Serve.
+	//
+	// See fuse.Debug for the rules that log functions must follow.
+	Debug func(msg interface{})
+
+	// Function to put things into context for processing the request.
+	// The returned context must have ctx as its parent.
+	//
+	// Note that changing this may not affect existing calls to Serve.
+	//
+	// Must not retain req.
+	WithContext func(ctx context.Context, req fuse.Request) context.Context
+}
+
+// New returns a new FUSE server ready to serve this kernel FUSE
+// connection.
+//
+// Config may be nil.
+func New(conn *fuse.Conn, config *Config) *Server {
+	s := &Server{
+		conn:         conn,
+		req:          map[fuse.RequestID]*serveRequest{},
+		nodeRef:      map[Node]fuse.NodeID{},
+		dynamicInode: GenerateDynamicInode,
+	}
+	if config != nil {
+		s.debug = config.Debug
+		s.context = config.WithContext
+	}
+	if s.debug == nil {
+		s.debug = fuse.Debug
+	}
+	return s
+}
+
+type Server struct {
+	// set in New
+	conn    *fuse.Conn
+	debug   func(msg interface{})
+	context func(ctx context.Context, req fuse.Request) context.Context
+
+	// set once at Serve time
+	fs           FS
+	dynamicInode func(parent uint64, name string) uint64
+
+	// state, protected by meta
+	meta       sync.Mutex
+	req        map[fuse.RequestID]*serveRequest
+	node       []*serveNode
+	nodeRef    map[Node]fuse.NodeID
+	handle     []*serveHandle
+	freeNode   []fuse.NodeID
+	freeHandle []fuse.HandleID
+	nodeGen    uint64
+
+	// Used to ensure worker goroutines finish before Serve returns
+	wg sync.WaitGroup
+}
+
+// Serve serves the FUSE connection by making calls to the methods
+// of fs and the Nodes and Handles it makes available.  It returns only
+// when the connection has been closed or an unexpected error occurs.
+func (s *Server) Serve(fs FS) error {
+	defer s.wg.Wait() // Wait for worker goroutines to complete before return
+
+	s.fs = fs
+	if dyn, ok := fs.(FSInodeGenerator); ok {
+		s.dynamicInode = dyn.GenerateInode
+	}
+
+	root, err := fs.Root()
+	if err != nil {
+		return fmt.Errorf("cannot obtain root node: %v", err)
+	}
+	// Recognize the root node if it's ever returned from Lookup,
+	// passed to Invalidate, etc.
+	s.nodeRef[root] = 1
+	s.node = append(s.node, nil, &serveNode{
+		inode:      1,
+		generation: s.nodeGen,
+		node:       root,
+		refs:       1,
+	})
+	s.handle = append(s.handle, nil)
+
+	for {
+		req, err := s.conn.ReadRequest()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return err
+		}
+
+		s.wg.Add(1)
+		go func() {
+			defer s.wg.Done()
+			s.serve(req)
+		}()
+	}
+	return nil
+}
+
+// Serve serves a FUSE connection with the default settings. See
+// Server.Serve.
+func Serve(c *fuse.Conn, fs FS) error {
+	server := New(c, nil)
+	return server.Serve(fs)
+}
+
+type nothing struct{}
+
+type serveRequest struct {
+	Request fuse.Request
+	cancel  func()
+}
+
+type serveNode struct {
+	inode      uint64
+	generation uint64
+	node       Node
+	refs       uint64
+
+	// Delay freeing the NodeID until waitgroup is done. This allows
+	// using the NodeID for short periods of time without holding the
+	// Server.meta lock.
+	//
+	// Rules:
+	//
+	//     - hold Server.meta while calling wg.Add, then unlock
+	//     - do NOT try to reacquire Server.meta
+	wg sync.WaitGroup
+}
+
+func (sn *serveNode) attr(ctx context.Context, attr *fuse.Attr) error {
+	err := nodeAttr(ctx, sn.node, attr)
+	if attr.Inode == 0 {
+		attr.Inode = sn.inode
+	}
+	return err
+}
+
+type serveHandle struct {
+	handle   Handle
+	readData []byte
+	nodeID   fuse.NodeID
+}
+
+// NodeRef is deprecated. It remains here to decrease code churn on
+// FUSE library users. You may remove it from your program now;
+// returning the same Node values are now recognized automatically,
+// without needing NodeRef.
+type NodeRef struct{}
+
+func (c *Server) saveNode(inode uint64, node Node) (id fuse.NodeID, gen uint64) {
+	c.meta.Lock()
+	defer c.meta.Unlock()
+
+	if id, ok := c.nodeRef[node]; ok {
+		sn := c.node[id]
+		sn.refs++
+		return id, sn.generation
+	}
+
+	sn := &serveNode{inode: inode, node: node, refs: 1}
+	if n := len(c.freeNode); n > 0 {
+		id = c.freeNode[n-1]
+		c.freeNode = c.freeNode[:n-1]
+		c.node[id] = sn
+		c.nodeGen++
+	} else {
+		id = fuse.NodeID(len(c.node))
+		c.node = append(c.node, sn)
+	}
+	sn.generation = c.nodeGen
+	c.nodeRef[node] = id
+	return id, sn.generation
+}
+
+func (c *Server) saveHandle(handle Handle, nodeID fuse.NodeID) (id fuse.HandleID) {
+	c.meta.Lock()
+	shandle := &serveHandle{handle: handle, nodeID: nodeID}
+	if n := len(c.freeHandle); n > 0 {
+		id = c.freeHandle[n-1]
+		c.freeHandle = c.freeHandle[:n-1]
+		c.handle[id] = shandle
+	} else {
+		id = fuse.HandleID(len(c.handle))
+		c.handle = append(c.handle, shandle)
+	}
+	c.meta.Unlock()
+	return
+}
+
+type nodeRefcountDropBug struct {
+	N    uint64
+	Refs uint64
+	Node fuse.NodeID
+}
+
+func (n *nodeRefcountDropBug) String() string {
+	return fmt.Sprintf("bug: trying to drop %d of %d references to %v", n.N, n.Refs, n.Node)
+}
+
+func (c *Server) dropNode(id fuse.NodeID, n uint64) (forget bool) {
+	c.meta.Lock()
+	defer c.meta.Unlock()
+	snode := c.node[id]
+
+	if snode == nil {
+		// this should only happen if refcounts kernel<->us disagree
+		// *and* two ForgetRequests for the same node race each other;
+		// this indicates a bug somewhere
+		c.debug(nodeRefcountDropBug{N: n, Node: id})
+
+		// we may end up triggering Forget twice, but that's better
+		// than not even once, and that's the best we can do
+		return true
+	}
+
+	if n > snode.refs {
+		c.debug(nodeRefcountDropBug{N: n, Refs: snode.refs, Node: id})
+		n = snode.refs
+	}
+
+	snode.refs -= n
+	if snode.refs == 0 {
+		snode.wg.Wait()
+		c.node[id] = nil
+		delete(c.nodeRef, snode.node)
+		c.freeNode = append(c.freeNode, id)
+		return true
+	}
+	return false
+}
+
+func (c *Server) dropHandle(id fuse.HandleID) {
+	c.meta.Lock()
+	c.handle[id] = nil
+	c.freeHandle = append(c.freeHandle, id)
+	c.meta.Unlock()
+}
+
+type missingHandle struct {
+	Handle    fuse.HandleID
+	MaxHandle fuse.HandleID
+}
+
+func (m missingHandle) String() string {
+	return fmt.Sprint("missing handle: ", m.Handle, m.MaxHandle)
+}
+
+// Returns nil for invalid handles.
+func (c *Server) getHandle(id fuse.HandleID) (shandle *serveHandle) {
+	c.meta.Lock()
+	defer c.meta.Unlock()
+	if id < fuse.HandleID(len(c.handle)) {
+		shandle = c.handle[uint(id)]
+	}
+	if shandle == nil {
+		c.debug(missingHandle{
+			Handle:    id,
+			MaxHandle: fuse.HandleID(len(c.handle)),
+		})
+	}
+	return
+}
+
+type request struct {
+	Op      string
+	Request *fuse.Header
+	In      interface{} `json:",omitempty"`
+}
+
+func (r request) String() string {
+	return fmt.Sprintf("<- %s", r.In)
+}
+
+type logResponseHeader struct {
+	ID fuse.RequestID
+}
+
+func (m logResponseHeader) String() string {
+	return fmt.Sprintf("ID=%v", m.ID)
+}
+
+type response struct {
+	Op      string
+	Request logResponseHeader
+	Out     interface{} `json:",omitempty"`
+	// Errno contains the errno value as a string, for example "EPERM".
+	Errno string `json:",omitempty"`
+	// Error may contain a free form error message.
+	Error string `json:",omitempty"`
+}
+
+func (r response) errstr() string {
+	s := r.Errno
+	if r.Error != "" {
+		// prefix the errno constant to the long form message
+		s = s + ": " + r.Error
+	}
+	return s
+}
+
+func (r response) String() string {
+	switch {
+	case r.Errno != "" && r.Out != nil:
+		return fmt.Sprintf("-> [%v] %v error=%s", r.Request, r.Out, r.errstr())
+	case r.Errno != "":
+		return fmt.Sprintf("-> [%v] %s error=%s", r.Request, r.Op, r.errstr())
+	case r.Out != nil:
+		// make sure (seemingly) empty values are readable
+		switch r.Out.(type) {
+		case string:
+			return fmt.Sprintf("-> [%v] %s %q", r.Request, r.Op, r.Out)
+		case []byte:
+			return fmt.Sprintf("-> [%v] %s [% x]", r.Request, r.Op, r.Out)
+		default:
+			return fmt.Sprintf("-> [%v] %v", r.Request, r.Out)
+		}
+	default:
+		return fmt.Sprintf("-> [%v] %s", r.Request, r.Op)
+	}
+}
+
+type notification struct {
+	Op   string
+	Node fuse.NodeID
+	Out  interface{} `json:",omitempty"`
+	Err  string      `json:",omitempty"`
+}
+
+func (n notification) String() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "=> %s %v", n.Op, n.Node)
+	if n.Out != nil {
+		// make sure (seemingly) empty values are readable
+		switch n.Out.(type) {
+		case string:
+			fmt.Fprintf(&buf, " %q", n.Out)
+		case []byte:
+			fmt.Fprintf(&buf, " [% x]", n.Out)
+		default:
+			fmt.Fprintf(&buf, " %s", n.Out)
+		}
+	}
+	if n.Err != "" {
+		fmt.Fprintf(&buf, " Err:%v", n.Err)
+	}
+	return buf.String()
+}
+
+type logMissingNode struct {
+	MaxNode fuse.NodeID
+}
+
+func opName(req fuse.Request) string {
+	t := reflect.Indirect(reflect.ValueOf(req)).Type()
+	s := t.Name()
+	s = strings.TrimSuffix(s, "Request")
+	return s
+}
+
+type logLinkRequestOldNodeNotFound struct {
+	Request *fuse.Header
+	In      *fuse.LinkRequest
+}
+
+func (m *logLinkRequestOldNodeNotFound) String() string {
+	return fmt.Sprintf("In LinkRequest (request %v), node %d not found", m.Request.Hdr().ID, m.In.OldNode)
+}
+
+type renameNewDirNodeNotFound struct {
+	Request *fuse.Header
+	In      *fuse.RenameRequest
+}
+
+func (m *renameNewDirNodeNotFound) String() string {
+	return fmt.Sprintf("In RenameRequest (request %v), node %d not found", m.Request.Hdr().ID, m.In.NewDir)
+}
+
+type handlerPanickedError struct {
+	Request interface{}
+	Err     interface{}
+}
+
+var _ error = handlerPanickedError{}
+
+func (h handlerPanickedError) Error() string {
+	return fmt.Sprintf("handler panicked: %v", h.Err)
+}
+
+var _ fuse.ErrorNumber = handlerPanickedError{}
+
+func (h handlerPanickedError) Errno() fuse.Errno {
+	if err, ok := h.Err.(fuse.ErrorNumber); ok {
+		return err.Errno()
+	}
+	return fuse.DefaultErrno
+}
+
+// handlerTerminatedError happens when a handler terminates itself
+// with runtime.Goexit. This is most commonly because of incorrect use
+// of testing.TB.FailNow, typically via t.Fatal.
+type handlerTerminatedError struct {
+	Request interface{}
+}
+
+var _ error = handlerTerminatedError{}
+
+func (h handlerTerminatedError) Error() string {
+	return fmt.Sprintf("handler terminated (called runtime.Goexit)")
+}
+
+var _ fuse.ErrorNumber = handlerTerminatedError{}
+
+func (h handlerTerminatedError) Errno() fuse.Errno {
+	return fuse.DefaultErrno
+}
+
+type handleNotReaderError struct {
+	handle Handle
+}
+
+var _ error = handleNotReaderError{}
+
+func (e handleNotReaderError) Error() string {
+	return fmt.Sprintf("handle has no Read: %T", e.handle)
+}
+
+var _ fuse.ErrorNumber = handleNotReaderError{}
+
+func (e handleNotReaderError) Errno() fuse.Errno {
+	return fuse.ENOTSUP
+}
+
+func initLookupResponse(s *fuse.LookupResponse) {
+	s.EntryValid = entryValidTime
+}
+
+func (c *Server) serve(r fuse.Request) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	parentCtx := ctx
+	if c.context != nil {
+		ctx = c.context(ctx, r)
+	}
+
+	req := &serveRequest{Request: r, cancel: cancel}
+
+	c.debug(request{
+		Op:      opName(r),
+		Request: r.Hdr(),
+		In:      r,
+	})
+	var node Node
+	var snode *serveNode
+	c.meta.Lock()
+	hdr := r.Hdr()
+	if id := hdr.Node; id != 0 {
+		if id < fuse.NodeID(len(c.node)) {
+			snode = c.node[uint(id)]
+		}
+		if snode == nil {
+			c.meta.Unlock()
+			c.debug(response{
+				Op:      opName(r),
+				Request: logResponseHeader{ID: hdr.ID},
+				Error:   fuse.ESTALE.ErrnoName(),
+				// this is the only place that sets both Error and
+				// Out; not sure if i want to do that; might get rid
+				// of len(c.node) things altogether
+				Out: logMissingNode{
+					MaxNode: fuse.NodeID(len(c.node)),
+				},
+			})
+			r.RespondError(fuse.ESTALE)
+			return
+		}
+		node = snode.node
+	}
+	if c.req[hdr.ID] != nil {
+		// This happens with OSXFUSE.  Assume it's okay and
+		// that we'll never see an interrupt for this one.
+		// Otherwise everything wedges.  TODO: Report to OSXFUSE?
+		//
+		// TODO this might have been because of missing done() calls
+	} else {
+		c.req[hdr.ID] = req
+	}
+	c.meta.Unlock()
+
+	// Call this before responding.
+	// After responding is too late: we might get another request
+	// with the same ID and be very confused.
+	done := func(resp interface{}) {
+		msg := response{
+			Op:      opName(r),
+			Request: logResponseHeader{ID: hdr.ID},
+		}
+		if err, ok := resp.(error); ok {
+			msg.Error = err.Error()
+			if ferr, ok := err.(fuse.ErrorNumber); ok {
+				errno := ferr.Errno()
+				msg.Errno = errno.ErrnoName()
+				if errno == err {
+					// it's just a fuse.Errno with no extra detail;
+					// skip the textual message for log readability
+					msg.Error = ""
+				}
+			} else {
+				msg.Errno = fuse.DefaultErrno.ErrnoName()
+			}
+		} else {
+			msg.Out = resp
+		}
+		c.debug(msg)
+
+		c.meta.Lock()
+		delete(c.req, hdr.ID)
+		c.meta.Unlock()
+	}
+
+	var responded bool
+	defer func() {
+		if rec := recover(); rec != nil {
+			const size = 1 << 16
+			buf := make([]byte, size)
+			n := runtime.Stack(buf, false)
+			buf = buf[:n]
+			log.Printf("fuse: panic in handler for %v: %v\n%s", r, rec, buf)
+			err := handlerPanickedError{
+				Request: r,
+				Err:     rec,
+			}
+			done(err)
+			r.RespondError(err)
+			return
+		}
+
+		if !responded {
+			err := handlerTerminatedError{
+				Request: r,
+			}
+			done(err)
+			r.RespondError(err)
+		}
+	}()
+
+	if err := c.handleRequest(ctx, node, snode, r, done); err != nil {
+		if err == context.Canceled {
+			select {
+			case <-parentCtx.Done():
+				// We canceled the parent context because of an
+				// incoming interrupt request, so return EINTR
+				// to trigger the right behavior in the client app.
+				//
+				// Only do this when it's the parent context that was
+				// canceled, not a context controlled by the program
+				// using this library, so we don't return EINTR too
+				// eagerly -- it might cause busy loops.
+				//
+				// Decent write-up on role of EINTR:
+				// http://250bpm.com/blog:12
+				err = fuse.EINTR
+			default:
+				// nothing
+			}
+		}
+		done(err)
+		r.RespondError(err)
+	}
+
+	// disarm runtime.Goexit protection
+	responded = true
+}
+
+// handleRequest will either a) call done(s) and r.Respond(s) OR b) return an error.
+func (c *Server) handleRequest(ctx context.Context, node Node, snode *serveNode, r fuse.Request, done func(resp interface{})) error {
+	switch r := r.(type) {
+	default:
+		// Note: To FUSE, ENOSYS means "this server never implements this request."
+		// It would be inappropriate to return ENOSYS for other operations in this
+		// switch that might only be unavailable in some contexts, not all.
+		return fuse.ENOSYS
+
+	case *fuse.StatfsRequest:
+		s := &fuse.StatfsResponse{}
+		if fs, ok := c.fs.(FSStatfser); ok {
+			if err := fs.Statfs(ctx, r, s); err != nil {
+				return err
+			}
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	// Node operations.
+	case *fuse.GetattrRequest:
+		s := &fuse.GetattrResponse{}
+		if n, ok := node.(NodeGetattrer); ok {
+			if err := n.Getattr(ctx, r, s); err != nil {
+				return err
+			}
+		} else {
+			if err := snode.attr(ctx, &s.Attr); err != nil {
+				return err
+			}
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.SetattrRequest:
+		s := &fuse.SetattrResponse{}
+		if n, ok := node.(NodeSetattrer); ok {
+			if err := n.Setattr(ctx, r, s); err != nil {
+				return err
+			}
+		}
+
+		if err := snode.attr(ctx, &s.Attr); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.SymlinkRequest:
+		s := &fuse.SymlinkResponse{}
+		initLookupResponse(&s.LookupResponse)
+		n, ok := node.(NodeSymlinker)
+		if !ok {
+			return fuse.EIO // XXX or EPERM like Mkdir?
+		}
+		n2, err := n.Symlink(ctx, r)
+		if err != nil {
+			return err
+		}
+		if err := c.saveLookup(ctx, &s.LookupResponse, snode, r.NewName, n2); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.ReadlinkRequest:
+		n, ok := node.(NodeReadlinker)
+		if !ok {
+			return fuse.EIO /// XXX or EPERM?
+		}
+		target, err := n.Readlink(ctx, r)
+		if err != nil {
+			return err
+		}
+		done(target)
+		r.Respond(target)
+		return nil
+
+	case *fuse.LinkRequest:
+		n, ok := node.(NodeLinker)
+		if !ok {
+			return fuse.EIO /// XXX or EPERM?
+		}
+		c.meta.Lock()
+		var oldNode *serveNode
+		if int(r.OldNode) < len(c.node) {
+			oldNode = c.node[r.OldNode]
+		}
+		c.meta.Unlock()
+		if oldNode == nil {
+			c.debug(logLinkRequestOldNodeNotFound{
+				Request: r.Hdr(),
+				In:      r,
+			})
+			return fuse.EIO
+		}
+		n2, err := n.Link(ctx, r, oldNode.node)
+		if err != nil {
+			return err
+		}
+		s := &fuse.LookupResponse{}
+		initLookupResponse(s)
+		if err := c.saveLookup(ctx, s, snode, r.NewName, n2); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.RemoveRequest:
+		n, ok := node.(NodeRemover)
+		if !ok {
+			return fuse.EIO /// XXX or EPERM?
+		}
+		err := n.Remove(ctx, r)
+		if err != nil {
+			return err
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.AccessRequest:
+		if n, ok := node.(NodeAccesser); ok {
+			if err := n.Access(ctx, r); err != nil {
+				return err
+			}
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.LookupRequest:
+		var n2 Node
+		var err error
+		s := &fuse.LookupResponse{}
+		initLookupResponse(s)
+		if n, ok := node.(NodeStringLookuper); ok {
+			n2, err = n.Lookup(ctx, r.Name)
+		} else if n, ok := node.(NodeRequestLookuper); ok {
+			n2, err = n.Lookup(ctx, r, s)
+		} else {
+			return fuse.ENOENT
+		}
+		if err != nil {
+			return err
+		}
+		if err := c.saveLookup(ctx, s, snode, r.Name, n2); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.MkdirRequest:
+		s := &fuse.MkdirResponse{}
+		initLookupResponse(&s.LookupResponse)
+		n, ok := node.(NodeMkdirer)
+		if !ok {
+			return fuse.EPERM
+		}
+		n2, err := n.Mkdir(ctx, r)
+		if err != nil {
+			return err
+		}
+		if err := c.saveLookup(ctx, &s.LookupResponse, snode, r.Name, n2); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.OpenRequest:
+		s := &fuse.OpenResponse{}
+		var h2 Handle
+		if n, ok := node.(NodeOpener); ok {
+			hh, err := n.Open(ctx, r, s)
+			if err != nil {
+				return err
+			}
+			h2 = hh
+		} else {
+			h2 = node
+		}
+		s.Handle = c.saveHandle(h2, r.Hdr().Node)
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.CreateRequest:
+		n, ok := node.(NodeCreater)
+		if !ok {
+			// If we send back ENOSYS, FUSE will try mknod+open.
+			return fuse.EPERM
+		}
+		s := &fuse.CreateResponse{OpenResponse: fuse.OpenResponse{}}
+		initLookupResponse(&s.LookupResponse)
+		n2, h2, err := n.Create(ctx, r, s)
+		if err != nil {
+			return err
+		}
+		if err := c.saveLookup(ctx, &s.LookupResponse, snode, r.Name, n2); err != nil {
+			return err
+		}
+		s.Handle = c.saveHandle(h2, r.Hdr().Node)
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.GetxattrRequest:
+		n, ok := node.(NodeGetxattrer)
+		if !ok {
+			return fuse.ENOTSUP
+		}
+		s := &fuse.GetxattrResponse{}
+		err := n.Getxattr(ctx, r, s)
+		if err != nil {
+			return err
+		}
+		if r.Size != 0 && uint64(len(s.Xattr)) > uint64(r.Size) {
+			return fuse.ERANGE
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.ListxattrRequest:
+		n, ok := node.(NodeListxattrer)
+		if !ok {
+			return fuse.ENOTSUP
+		}
+		s := &fuse.ListxattrResponse{}
+		err := n.Listxattr(ctx, r, s)
+		if err != nil {
+			return err
+		}
+		if r.Size != 0 && uint64(len(s.Xattr)) > uint64(r.Size) {
+			return fuse.ERANGE
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.SetxattrRequest:
+		n, ok := node.(NodeSetxattrer)
+		if !ok {
+			return fuse.ENOTSUP
+		}
+		err := n.Setxattr(ctx, r)
+		if err != nil {
+			return err
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.RemovexattrRequest:
+		n, ok := node.(NodeRemovexattrer)
+		if !ok {
+			return fuse.ENOTSUP
+		}
+		err := n.Removexattr(ctx, r)
+		if err != nil {
+			return err
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.ForgetRequest:
+		forget := c.dropNode(r.Hdr().Node, r.N)
+		if forget {
+			n, ok := node.(NodeForgetter)
+			if ok {
+				n.Forget()
+			}
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	// Handle operations.
+	case *fuse.ReadRequest:
+		shandle := c.getHandle(r.Handle)
+		if shandle == nil {
+			return fuse.ESTALE
+		}
+		handle := shandle.handle
+
+		s := &fuse.ReadResponse{Data: make([]byte, 0, r.Size)}
+		if r.Dir {
+			if h, ok := handle.(HandleReadDirAller); ok {
+				// detect rewinddir(3) or similar seek and refresh
+				// contents
+				if r.Offset == 0 {
+					shandle.readData = nil
+				}
+
+				if shandle.readData == nil {
+					dirs, err := h.ReadDirAll(ctx)
+					if err != nil {
+						return err
+					}
+					var data []byte
+					for _, dir := range dirs {
+						if dir.Inode == 0 {
+							dir.Inode = c.dynamicInode(snode.inode, dir.Name)
+						}
+						data = fuse.AppendDirent(data, dir)
+					}
+					shandle.readData = data
+				}
+				fuseutil.HandleRead(r, s, shandle.readData)
+				done(s)
+				r.Respond(s)
+				return nil
+			}
+		} else {
+			if h, ok := handle.(HandleReadAller); ok {
+				if shandle.readData == nil {
+					data, err := h.ReadAll(ctx)
+					if err != nil {
+						return err
+					}
+					if data == nil {
+						data = []byte{}
+					}
+					shandle.readData = data
+				}
+				fuseutil.HandleRead(r, s, shandle.readData)
+				done(s)
+				r.Respond(s)
+				return nil
+			}
+			h, ok := handle.(HandleReader)
+			if !ok {
+				err := handleNotReaderError{handle: handle}
+				return err
+			}
+			if err := h.Read(ctx, r, s); err != nil {
+				return err
+			}
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.WriteRequest:
+		shandle := c.getHandle(r.Handle)
+		if shandle == nil {
+			return fuse.ESTALE
+		}
+
+		s := &fuse.WriteResponse{}
+		if h, ok := shandle.handle.(HandleWriter); ok {
+			if err := h.Write(ctx, r, s); err != nil {
+				return err
+			}
+			done(s)
+			r.Respond(s)
+			return nil
+		}
+		return fuse.EIO
+
+	case *fuse.FlushRequest:
+		shandle := c.getHandle(r.Handle)
+		if shandle == nil {
+			return fuse.ESTALE
+		}
+		handle := shandle.handle
+
+		if h, ok := handle.(HandleFlusher); ok {
+			if err := h.Flush(ctx, r); err != nil {
+				return err
+			}
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.ReleaseRequest:
+		shandle := c.getHandle(r.Handle)
+		if shandle == nil {
+			return fuse.ESTALE
+		}
+		handle := shandle.handle
+
+		// No matter what, release the handle.
+		c.dropHandle(r.Handle)
+
+		if h, ok := handle.(HandleReleaser); ok {
+			if err := h.Release(ctx, r); err != nil {
+				return err
+			}
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.DestroyRequest:
+		if fs, ok := c.fs.(FSDestroyer); ok {
+			fs.Destroy()
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.RenameRequest:
+		c.meta.Lock()
+		var newDirNode *serveNode
+		if int(r.NewDir) < len(c.node) {
+			newDirNode = c.node[r.NewDir]
+		}
+		c.meta.Unlock()
+		if newDirNode == nil {
+			c.debug(renameNewDirNodeNotFound{
+				Request: r.Hdr(),
+				In:      r,
+			})
+			return fuse.EIO
+		}
+		n, ok := node.(NodeRenamer)
+		if !ok {
+			return fuse.EIO // XXX or EPERM like Mkdir?
+		}
+		err := n.Rename(ctx, r, newDirNode.node)
+		if err != nil {
+			return err
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.MknodRequest:
+		n, ok := node.(NodeMknoder)
+		if !ok {
+			return fuse.EIO
+		}
+		n2, err := n.Mknod(ctx, r)
+		if err != nil {
+			return err
+		}
+		s := &fuse.LookupResponse{}
+		initLookupResponse(s)
+		if err := c.saveLookup(ctx, s, snode, r.Name, n2); err != nil {
+			return err
+		}
+		done(s)
+		r.Respond(s)
+		return nil
+
+	case *fuse.FsyncRequest:
+		n, ok := node.(NodeFsyncer)
+		if !ok {
+			return fuse.EIO
+		}
+		err := n.Fsync(ctx, r)
+		if err != nil {
+			return err
+		}
+		done(nil)
+		r.Respond()
+		return nil
+
+	case *fuse.InterruptRequest:
+		c.meta.Lock()
+		ireq := c.req[r.IntrID]
+		if ireq != nil && ireq.cancel != nil {
+			ireq.cancel()
+			ireq.cancel = nil
+		}
+		c.meta.Unlock()
+		done(nil)
+		r.Respond()
+		return nil
+
+		/*	case *FsyncdirRequest:
+				return ENOSYS
+
+			case *GetlkRequest, *SetlkRequest, *SetlkwRequest:
+				return ENOSYS
+
+			case *BmapRequest:
+				return ENOSYS
+
+			case *SetvolnameRequest, *GetxtimesRequest, *ExchangeRequest:
+				return ENOSYS
+		*/
+	}
+
+	panic("not reached")
+}
+
+func (c *Server) saveLookup(ctx context.Context, s *fuse.LookupResponse, snode *serveNode, elem string, n2 Node) error {
+	if err := nodeAttr(ctx, n2, &s.Attr); err != nil {
+		return err
+	}
+	if s.Attr.Inode == 0 {
+		s.Attr.Inode = c.dynamicInode(snode.inode, elem)
+	}
+
+	s.Node, s.Generation = c.saveNode(s.Attr.Inode, n2)
+	return nil
+}
+
+type invalidateNodeDetail struct {
+	Off  int64
+	Size int64
+}
+
+func (i invalidateNodeDetail) String() string {
+	return fmt.Sprintf("Off:%d Size:%d", i.Off, i.Size)
+}
+
+func errstr(err error) string {
+	if err == nil {
+		return ""
+	}
+	return err.Error()
+}
+
+func (s *Server) invalidateNode(node Node, off int64, size int64) error {
+	s.meta.Lock()
+	id, ok := s.nodeRef[node]
+	if ok {
+		snode := s.node[id]
+		snode.wg.Add(1)
+		defer snode.wg.Done()
+	}
+	s.meta.Unlock()
+	if !ok {
+		// This is what the kernel would have said, if we had been
+		// able to send this message; it's not cached.
+		return fuse.ErrNotCached
+	}
+	// Delay logging until after we can record the error too. We
+	// consider a /dev/fuse write to be instantaneous enough to not
+	// need separate before and after messages.
+	err := s.conn.InvalidateNode(id, off, size)
+	s.debug(notification{
+		Op:   "InvalidateNode",
+		Node: id,
+		Out: invalidateNodeDetail{
+			Off:  off,
+			Size: size,
+		},
+		Err: errstr(err),
+	})
+	return err
+}
+
+// InvalidateNodeAttr invalidates the kernel cache of the attributes
+// of node.
+//
+// Returns fuse.ErrNotCached if the kernel is not currently caching
+// the node.
+func (s *Server) InvalidateNodeAttr(node Node) error {
+	return s.invalidateNode(node, 0, 0)
+}
+
+// InvalidateNodeData invalidates the kernel cache of the attributes
+// and data of node.
+//
+// Returns fuse.ErrNotCached if the kernel is not currently caching
+// the node.
+func (s *Server) InvalidateNodeData(node Node) error {
+	return s.invalidateNode(node, 0, -1)
+}
+
+// InvalidateNodeDataRange invalidates the kernel cache of the
+// attributes and a range of the data of node.
+//
+// Returns fuse.ErrNotCached if the kernel is not currently caching
+// the node.
+func (s *Server) InvalidateNodeDataRange(node Node, off int64, size int64) error {
+	return s.invalidateNode(node, off, size)
+}
+
+type invalidateEntryDetail struct {
+	Name string
+}
+
+func (i invalidateEntryDetail) String() string {
+	return fmt.Sprintf("%q", i.Name)
+}
+
+// InvalidateEntry invalidates the kernel cache of the directory entry
+// identified by parent node and entry basename.
+//
+// Kernel may or may not cache directory listings. To invalidate
+// those, use InvalidateNode to invalidate all of the data for a
+// directory. (As of 2015-06, Linux FUSE does not cache directory
+// listings.)
+//
+// Returns ErrNotCached if the kernel is not currently caching the
+// node.
+func (s *Server) InvalidateEntry(parent Node, name string) error {
+	s.meta.Lock()
+	id, ok := s.nodeRef[parent]
+	if ok {
+		snode := s.node[id]
+		snode.wg.Add(1)
+		defer snode.wg.Done()
+	}
+	s.meta.Unlock()
+	if !ok {
+		// This is what the kernel would have said, if we had been
+		// able to send this message; it's not cached.
+		return fuse.ErrNotCached
+	}
+	err := s.conn.InvalidateEntry(id, name)
+	s.debug(notification{
+		Op:   "InvalidateEntry",
+		Node: id,
+		Out: invalidateEntryDetail{
+			Name: name,
+		},
+		Err: errstr(err),
+	})
+	return err
+}
+
+// DataHandle returns a read-only Handle that satisfies reads
+// using the given data.
+func DataHandle(data []byte) Handle {
+	return &dataHandle{data}
+}
+
+type dataHandle struct {
+	data []byte
+}
+
+func (d *dataHandle) ReadAll(ctx context.Context) ([]byte, error) {
+	return d.data, nil
+}
+
+// GenerateDynamicInode returns a dynamic inode.
+//
+// The parent inode and current entry name are used as the criteria
+// for choosing a pseudorandom inode. This makes it likely the same
+// entry will get the same inode on multiple runs.
+func GenerateDynamicInode(parent uint64, name string) uint64 {
+	h := fnv.New64a()
+	var buf [8]byte
+	binary.LittleEndian.PutUint64(buf[:], parent)
+	_, _ = h.Write(buf[:])
+	_, _ = h.Write([]byte(name))
+	var inode uint64
+	for {
+		inode = h.Sum64()
+		if inode != 0 {
+			break
+		}
+		// there's a tiny probability that result is zero; change the
+		// input a little and try again
+		_, _ = h.Write([]byte{'x'})
+	}
+	return inode
+}
diff --git a/vendor/bazil.org/fuse/fs/tree.go b/vendor/bazil.org/fuse/fs/tree.go
new file mode 100644
index 000000000..7e078045a
--- /dev/null
+++ b/vendor/bazil.org/fuse/fs/tree.go
@@ -0,0 +1,99 @@
+// FUSE directory tree, for servers that wish to use it with the service loop.
+
+package fs
+
+import (
+	"os"
+	pathpkg "path"
+	"strings"
+
+	"golang.org/x/net/context"
+)
+
+import (
+	"bazil.org/fuse"
+)
+
+// A Tree implements a basic read-only directory tree for FUSE.
+// The Nodes contained in it may still be writable.
+type Tree struct {
+	tree
+}
+
+func (t *Tree) Root() (Node, error) {
+	return &t.tree, nil
+}
+
+// Add adds the path to the tree, resolving to the given node.
+// If path or a prefix of path has already been added to the tree,
+// Add panics.
+//
+// Add is only safe to call before starting to serve requests.
+func (t *Tree) Add(path string, node Node) {
+	path = pathpkg.Clean("/" + path)[1:]
+	elems := strings.Split(path, "/")
+	dir := Node(&t.tree)
+	for i, elem := range elems {
+		dt, ok := dir.(*tree)
+		if !ok {
+			panic("fuse: Tree.Add for " + strings.Join(elems[:i], "/") + " and " + path)
+		}
+		n := dt.lookup(elem)
+		if n != nil {
+			if i+1 == len(elems) {
+				panic("fuse: Tree.Add for " + path + " conflicts with " + elem)
+			}
+			dir = n
+		} else {
+			if i+1 == len(elems) {
+				dt.add(elem, node)
+			} else {
+				dir = &tree{}
+				dt.add(elem, dir)
+			}
+		}
+	}
+}
+
+type treeDir struct {
+	name string
+	node Node
+}
+
+type tree struct {
+	dir []treeDir
+}
+
+func (t *tree) lookup(name string) Node {
+	for _, d := range t.dir {
+		if d.name == name {
+			return d.node
+		}
+	}
+	return nil
+}
+
+func (t *tree) add(name string, n Node) {
+	t.dir = append(t.dir, treeDir{name, n})
+}
+
+func (t *tree) Attr(ctx context.Context, a *fuse.Attr) error {
+	a.Mode = os.ModeDir | 0555
+	return nil
+}
+
+func (t *tree) Lookup(ctx context.Context, name string) (Node, error) {
+	n := t.lookup(name)
+	if n != nil {
+		return n, nil
+	}
+	return nil, fuse.ENOENT
+}
+
+func (t *tree) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
+	var out []fuse.Dirent
+	for _, d := range t.dir {
+		out = append(out, fuse.Dirent{Name: d.name})
+	}
+	return out, nil
+}