fuse/nodefs: support reading from and writing to Nodes directly.

fuse/nodefs/api.go

@@ -76,6 +76,11 @@ type Node interface {
 
 	// Create should return an open file, and the Inode for that file.
 	Create(name string, flags uint32, mode uint32, context *fuse.Context) (file File, child *Inode, code fuse.Status)
+
+	// Open opens a file, and returns a File which is associated
+	// with a file handle. It is OK to return (nil, OK) here. In
+	// that case, the Node should implement Read or Write
+	// directly.
 	Open(flags uint32, context *fuse.Context) (file File, code fuse.Status)
 	OpenDir(context *fuse.Context) ([]fuse.DirEntry, fuse.Status)
 
@@ -86,6 +91,8 @@ type Node interface {
 	ListXAttr(context *fuse.Context) (attrs []string, code fuse.Status)
 
 	// Attributes
+	Read(file File, dest []byte, off int64, context *fuse.Context) (fuse.ReadResult, fuse.Status)
+	Write(file File, data []byte, off int64, context *fuse.Context) (written uint32, code fuse.Status)
 	GetAttr(out *fuse.Attr, file File, context *fuse.Context) (code fuse.Status)
 	Chmod(file File, perms uint32, context *fuse.Context) (code fuse.Status)
 	Chown(file File, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status)
@@ -96,7 +103,7 @@ type Node interface {
 	StatFs() *fuse.StatfsOut
 }
 
-// A File object should be returned from FileSystem.Open and
+// A File object is returned from FileSystem.Open and
 // FileSystem.Create.  Include the NewDefaultFile return value into
 // the struct to inherit a null implementation.
 type File interface {

fuse/nodefs/defaultnode.go

@@ -149,3 +149,17 @@ func (n *defaultNode) Utimens(file File, atime *time.Time, mtime *time.Time, con
 func (n *defaultNode) Fallocate(file File, off uint64, size uint64, mode uint32, context *fuse.Context) (code fuse.Status) {
 	return fuse.ENOSYS
 }
+
+func (n *defaultNode) Read(file File, dest []byte, off int64, context *fuse.Context) (fuse.ReadResult, fuse.Status) {
+	if file != nil {
+		return file.Read(dest, off)
+	}
+	return nil, fuse.ENOSYS
+}
+
+func (n *defaultNode) Write(file File, data []byte, off int64, context *fuse.Context) (written uint32, code fuse.Status) {
+	if file != nil {
+		return file.Write(data, off)
+	}
+	return 0, fuse.ENOSYS
+}

fuse/nodefs/fileless_test.go

+package nodefs
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/hanwen/go-fuse/fuse"
+)
+
+type nodeReadNode struct {
+	Node
+	data []byte
+}
+
+func newNodeReadNode(d []byte) *nodeReadNode {
+	return &nodeReadNode{NewDefaultNode(), d}
+}
+
+func (n *nodeReadNode) Open(flags uint32, context *fuse.Context) (file File, code fuse.Status) {
+	return nil, fuse.OK
+}
+
+func (n *nodeReadNode) Read(file File, dest []byte, off int64, context *fuse.Context) (fuse.ReadResult, fuse.Status) {
+	e := off + int64(len(dest))
+	if int(e) > len(n.data) {
+		e = int64(len(n.data))
+	}
+	return fuse.ReadResultData(n.data[off:int(e)]), fuse.OK
+}
+
+func (n *nodeReadNode) Lookup(out *fuse.Attr, name string, context *fuse.Context) (*Inode, fuse.Status) {
+	out.Mode = fuse.S_IFREG | 0644
+	out.Size = uint64(len(name))
+	ch := n.Inode().NewChild(name, false, newNodeReadNode([]byte(name)))
+	return ch, fuse.OK
+}
+
+func TestNodeRead(t *testing.T) {
+	dir, err := ioutil.TempDir("", "nodefs")
+	if err != nil {
+		t.Fatalf("TempDir: %v", err)
+	}
+
+	root := newNodeReadNode([]byte("root"))
+	s, _, err := MountRoot(dir, root, nil)
+	if err != nil {
+		t.Fatalf("MountRoot: %v", err)
+	}
+	s.SetDebug(true)
+	go s.Serve()
+	defer s.Unmount()
+	content, err := ioutil.ReadFile(dir + "/file")
+	if err != nil {
+		t.Fatalf("MountRoot: %v", err)
+	}
+	want := "file"
+	if string(content) != want {
+		t.Fatalf("got %q, want %q", content, want)
+	}
+}

fuse/nodefs/fsmount.go

@@ -75,8 +75,12 @@ func (m *fileSystemMount) fillAttr(out *fuse.AttrOut, nodeId uint64) {
 }
 
 func (m *fileSystemMount) getOpenedFile(h uint64) *openedFile {
-	b := (*openedFile)(unsafe.Pointer(m.openFiles.Decode(h)))
-	if m.connector.debug && b.WithFlags.Description != "" {
+	var b *openedFile
+	if h != 0 {
+		b = (*openedFile)(unsafe.Pointer(m.openFiles.Decode(h)))
+	}
+
+	if b != nil && m.connector.debug && b.WithFlags.Description != "" {
 		log.Printf("File %d = %q", h, b.WithFlags.Description)
 	}
 	return b

fuse/nodefs/fsops.go

@@ -164,7 +164,7 @@ func (c *rawBridge) ReadDirPlus(input *fuse.ReadIn, out *fuse.DirEntryList) fuse
 func (c *rawBridge) Open(input *fuse.OpenIn, out *fuse.OpenOut) (status fuse.Status) {
 	node := c.toInode(input.NodeId)
 	f, code := node.fsInode.Open(input.Flags, &input.Context)
-	if !code.Ok() {
+	if !code.Ok() || f == nil {
 		return code
 	}
 	h, opened := node.mount.registerFileHandle(node, nil, f, input.Flags)
@@ -344,14 +344,18 @@ func (c *rawBridge) Create(input *fuse.CreateIn, name string, out *fuse.CreateOu
 }
 
 func (c *rawBridge) Release(input *fuse.ReleaseIn) {
-	node := c.toInode(input.NodeId)
-	opened := node.mount.unregisterFileHandle(input.Fh, node)
-	opened.WithFlags.File.Release()
+	if input.Fh != 0 {
+		node := c.toInode(input.NodeId)
+		opened := node.mount.unregisterFileHandle(input.Fh, node)
+		opened.WithFlags.File.Release()
+	}
 }
 
 func (c *rawBridge) ReleaseDir(input *fuse.ReleaseIn) {
-	node := c.toInode(input.NodeId)
-	node.mount.unregisterFileHandle(input.Fh, node)
+	if input.Fh != 0 {
+		node := c.toInode(input.NodeId)
+		node.mount.unregisterFileHandle(input.Fh, node)
+	}
 }
 
 func (c *rawBridge) GetXAttrSize(header *fuse.InHeader, attribute string) (sz int, code fuse.Status) {
@@ -397,14 +401,25 @@ func (c *rawBridge) ListXAttr(header *fuse.InHeader) (data []byte, code fuse.Sta
 func (c *rawBridge) Write(input *fuse.WriteIn, data []byte) (written uint32, code fuse.Status) {
 	node := c.toInode(input.NodeId)
 	opened := node.mount.getOpenedFile(input.Fh)
-	return opened.WithFlags.File.Write(data, int64(input.Offset))
+
+	var f File
+	if opened != nil {
+		f = opened.WithFlags.File
+	}
+
+	return node.Node().Write(f, data, int64(input.Offset), &input.Context)
 }
 
 func (c *rawBridge) Read(input *fuse.ReadIn, buf []byte) (fuse.ReadResult, fuse.Status) {
 	node := c.toInode(input.NodeId)
 	opened := node.mount.getOpenedFile(input.Fh)
 
-	return opened.WithFlags.File.Read(buf, int64(input.Offset))
+	var f File
+	if opened != nil {
+		f = opened.WithFlags.File
+	}
+
+	return node.Node().Read(f, buf, int64(input.Offset), &input.Context)
 }
 
 func (c *rawBridge) StatFs(header *fuse.InHeader, out *fuse.StatfsOut) fuse.Status {
@@ -420,5 +435,9 @@ func (c *rawBridge) StatFs(header *fuse.InHeader, out *fuse.StatfsOut) fuse.Stat
 func (c *rawBridge) Flush(input *fuse.FlushIn) fuse.Status {
 	node := c.toInode(input.NodeId)
 	opened := node.mount.getOpenedFile(input.Fh)
-	return opened.WithFlags.File.Flush()
+
+	if opened != nil {
+		return opened.WithFlags.File.Flush()
+	}
+	return fuse.OK
 }

fuse/pathfs/pathfs.go

@@ -719,3 +719,17 @@ func (n *pathInode) Fallocate(file nodefs.File, off uint64, size uint64, mode ui
 
 	return code
 }
+
+func (n *pathInode) Read(file nodefs.File, dest []byte, off int64, context *fuse.Context) (fuse.ReadResult, fuse.Status) {
+	if file != nil {
+		return file.Read(dest, off)
+	}
+	return nil, fuse.ENOSYS
+}
+
+func (n *pathInode) Write(file nodefs.File, data []byte, off int64, context *fuse.Context) (written uint32, code fuse.Status) {
+	if file != nil {
+		return file.Write(data, off)
+	}
+	return 0, fuse.ENOSYS
+}