fuse: support extended attributes

Change-Id: I0698d5adfc756bf8f589f2cdbb0057f2789cd40a

third_party/code.google.com/p/rsc/fuse/fuse.go

@@ -594,12 +594,15 @@ func (c *Conn) ReadRequest() (Request, error) {
 		req = r
 
 	case opGetxattr:
+		var r *GetxattrRequest
+		nameOff := 8
 		if runtime.GOOS == "darwin" {
 			in := (*getxattrInOSX)(m.data())
 			if m.len() < unsafe.Sizeof(*in) {
 				goto corrupt
 			}
-			req = &GetxattrRequest{
+			nameOff += 8
+			r = &GetxattrRequest{
 				Header:   m.Header(),
 				Size:     in.Size,
 				Position: in.Position,
@@ -609,11 +612,19 @@ func (c *Conn) ReadRequest() (Request, error) {
 			if m.len() < unsafe.Sizeof(*in) {
 				goto corrupt
 			}
-			req = &GetxattrRequest{
+			r = &GetxattrRequest{
 				Header: m.Header(),
 				Size:   in.Size,
 			}
 		}
+		r.Header = m.Header()
+		name := m.bytes()[nameOff:]
+		i := bytes.IndexByte(name, 0)
+		if i < 0 {
+			goto corrupt
+		}
+		r.Name = string(name[:i])
+		req = r
 
 	case opListxattr:
 		if runtime.GOOS == "darwin" {
@@ -987,6 +998,7 @@ type GetxattrRequest struct {
 	Header
 	Size     uint32 // maximum size to return
 	Position uint32 // offset within extended attributes
+	Name     string // Name of the attribute being requested
 }
 
 func (r *GetxattrRequest) String() string {
@@ -995,11 +1007,16 @@ func (r *GetxattrRequest) String() string {
 
 // Respond replies to the request with the given response.
 func (r *GetxattrRequest) Respond(resp *GetxattrResponse) {
-	out := &getxattrOut{
-		outHeader: outHeader{Unique: uint64(r.ID)},
-		Size:      uint32(len(resp.Xattr)),
+	hdr := outHeader{Unique: uint64(r.ID)}
+	if r.Size == 0 {
+		out := &getxattrOut{
+			outHeader: hdr,
+			Size:      uint32(len(resp.Xattr)),
+		}
+		r.Conn.respond(&out.outHeader, unsafe.Sizeof(*out))
+	} else {
+		r.Conn.respondData(&hdr, unsafe.Sizeof(hdr), resp.Xattr)
 	}
-	r.Conn.respondData(&out.outHeader, unsafe.Sizeof(*out), resp.Xattr)
 }
 
 // A GetxattrResponse is the response to a GetxattrRequest.
@@ -1024,18 +1041,39 @@ func (r *ListxattrRequest) String() string {
 
 // Respond replies to the request with the given response.
 func (r *ListxattrRequest) Respond(resp *ListxattrResponse) {
-	out := &getxattrOut{
-		outHeader: outHeader{Unique: uint64(r.ID)},
-		Size:      uint32(len(resp.Xattr)),
+	hdr := outHeader{Unique: uint64(r.ID)}
+	if r.Size == 0 {
+		out := &getxattrOut{
+			outHeader: hdr,
+			Size:      resp.Size,
+		}
+		r.Conn.respond(&out.outHeader, unsafe.Sizeof(*out))
+	} else {
+		r.Conn.respondData(&hdr, unsafe.Sizeof(hdr), resp.Xattr)
 	}
-	r.Conn.respondData(&out.outHeader, unsafe.Sizeof(*out), resp.Xattr)
 }
 
 // A ListxattrResponse is the response to a ListxattrRequest.
 type ListxattrResponse struct {
+	Size  uint32
 	Xattr []byte
 }
 
+// SetattrNames initializes the ListxattrResponse with the list of
+// attribute names.
+func (l *ListxattrResponse) SetAttrNames(req *ListxattrRequest, to []string) {
+	var buf bytes.Buffer
+	for _, b := range to {
+		buf.WriteString(b)
+		buf.WriteByte(0)
+	}
+	l.Size = uint32(buf.Len())
+	l.Xattr = buf.Bytes()
+	if len(l.Xattr) > int(req.Size) {
+		l.Xattr = l.Xattr[:req.Size]
+	}
+}
+
 func (r *ListxattrResponse) String() string {
 	return fmt.Sprintf("Listxattr %x", r.Xattr)
 }

third_party/code.google.com/p/rsc/fuse/serve.go

@@ -92,16 +92,18 @@ type FS interface {
 // 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.
 //
-//	Getxattr
+//	Getxattr(req *GetxattrRequest, res *GetxattrResponse, intr Intr) fuse.Error
 //
-// Getxattr obtains an extended attribute for the receiver.
-// XXX
+// Getxattr obtains an extended attribute for the receiver.  If the
+// attribute is not found, fuse.ENOATTR should be returned.
+//
+//	Listxattr(req *ListxattrRequest, *ListxattrResponse) Error
 //
-//	Listxattr
-// 
 // Listxattr lists the extended attributes recorded for the receiver.
+// The response method SetAttrNames(*ListxattrRequest, []string) takes
+// care of the encoding.
 //
-//	Removexattr
+//	Removexattr(req *RemotexattrRequest) fuse.Error
 //
 // Removexattr removes an extended attribute from the receiver.
 //
@@ -109,7 +111,7 @@ type FS interface {
 //
 // Setattr sets the standard metadata for the receiver.
 //
-//	Setxattr
+//	Setxattr(req *SetxattrRequest) fuse.Error
 //
 // Setxattr sets an extended attribute for the receiver.
 //
@@ -741,10 +743,80 @@ func (c *Conn) serve(fs FS, r Request) {
 		done(s)
 		r.Respond(s)
 
-	case *GetxattrRequest, *SetxattrRequest, *ListxattrRequest, *RemovexattrRequest:
-		// TODO: Use n.
-		done(ENOSYS)
-		r.RespondError(ENOSYS)
+	case *GetxattrRequest:
+		n, ok := node.(interface {
+			Getxattr(*GetxattrRequest, *GetxattrResponse, Intr) Error
+		})
+		if !ok {
+			done(ENOSYS)
+			r.RespondError(ENOSYS)
+			break
+		}
+		s := &GetxattrResponse{}
+		err := n.Getxattr(r, s, intr)
+		if err != nil {
+			done(err)
+			r.RespondError(err)
+			break
+		}
+		log.Printf("xattr response: %#v", s)
+		done(nil)
+		r.Respond(s)
+
+	case *SetxattrRequest:
+		n, ok := node.(interface {
+			Setxattr(*SetxattrRequest, Intr) Error
+		})
+		if !ok {
+			done(ENOSYS)
+			r.RespondError(ENOSYS)
+			break
+		}
+		err := n.Setxattr(r, intr)
+		if err != nil {
+			done(err)
+			r.RespondError(err)
+			break
+		}
+		done(nil)
+		r.Respond()
+
+	case *ListxattrRequest:
+		n, ok := node.(interface {
+			Listxattr(*ListxattrRequest, *ListxattrResponse, Intr) Error
+		})
+		s := &ListxattrResponse{}
+		if !ok {
+			done(nil)
+			r.Respond(s)
+			break
+		}
+		err := n.Listxattr(r, s, intr)
+		if err != nil {
+			done(err)
+			r.RespondError(err)
+			break
+		}
+		done(nil)
+		r.Respond(s)
+
+	case *RemovexattrRequest:
+		n, ok := node.(interface {
+			Removexattr(*RemovexattrRequest, Intr) Error
+		})
+		if !ok {
+			done(ENOSYS)
+			r.RespondError(ENOSYS)
+			break
+		}
+		err := n.Removexattr(r, intr)
+		if err != nil {
+			done(err)
+			r.RespondError(err)
+			break
+		}
+		done(nil)
+		r.Respond()
 
 	case *ForgetRequest:
 		n, ok := node.(interface {

third_party/code.google.com/p/rsc/fuse/xattr_darwin.go

@@ -0,0 +1,11 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fuse
+
+import "syscall"
+
+// ENOATTR is a fuse.Error returned when a request is made for an
+// extended attribute that doesn't exist.
+var ENOATTR = Errno(syscall.ENOATTR)

third_party/code.google.com/p/rsc/fuse/xattr_linux.go

@@ -0,0 +1,15 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fuse
+
+import "syscall"
+
+// This is mildly confusing, but the value to return when an attribute
+// doesn't exist seems to vary from system to system.
+// http://mail-index.netbsd.org/tech-kern/2012/04/30/msg013091.html
+
+// ENOATTR is a fuse.Error returned when a request is made for an
+// extended attribute that doesn't exist.
+var ENOATTR = Errno(syscall.ENODATA)