fsop: simplify Getxattr signature

examples/memfs/memfs.go

@@ -371,24 +371,21 @@ func (self *Memfs) Setxattr(path string, name string, value []byte, flags int) (
 	return 0
 }
 
-func (self *Memfs) Getxattr(path string, name string, fill func(value []byte) bool) (errc int) {
-	defer trace(path, name, fill)(&errc)
+func (self *Memfs) Getxattr(path string, name string) (errc int, xatr []byte) {
+	defer trace(path, name)(&errc, &xatr)
 	defer self.synchronize()()
 	_, _, node := self.lookupNode(path, nil)
 	if nil == node {
-		return -fuse.ENOENT
+		return -fuse.ENOENT, nil
 	}
 	if "com.apple.ResourceFork" == name {
-		return -fuse.ENOTSUP
+		return -fuse.ENOTSUP, nil
 	}
 	xatr, ok := node.xatr[name]
 	if !ok {
-		return -fuse.ENOATTR
+		return -fuse.ENOATTR, nil
 	}
-	if !fill(xatr) {
-		return -fuse.ERANGE
-	}
-	return 0
+	return 0, xatr
 }
 
 func (self *Memfs) Removexattr(path string, name string) (errc int) {

fuse/fsop.go

@@ -477,7 +477,7 @@ type FileSystemInterface interface {
 	Setxattr(path string, name string, value []byte, flags int) int
 
 	// Getxattr gets extended attributes.
-	Getxattr(path string, name string, fill func(value []byte) bool) int
+	Getxattr(path string, name string) (int, []byte)
 
 	// Removexattr removes extended attributes.
 	Removexattr(path string, name string) int
@@ -687,8 +687,8 @@ func (*FileSystemBase) Setxattr(path string, name string, value []byte, flags in
 
 // Getxattr gets extended attributes.
 // The FileSystemBase implementation returns -ENOSYS.
-func (*FileSystemBase) Getxattr(path string, name string, fill func(value []byte) bool) int {
-	return -ENOSYS
+func (*FileSystemBase) Getxattr(path string, name string) (int, []byte) {
+	return -ENOSYS, nil
 }
 
 // Removexattr removes extended attributes.

fuse/host.go

@@ -708,24 +708,18 @@ func hostGetxattr(path0 *C.char, name0 *C.char, buff0 *C.char, size0 C.size_t) (
 	fsop := getInterfaceForHandle(C.fuse_get_context().private_data).(FileSystemInterface)
 	path := C.GoString(path0)
 	name := C.GoString(name0)
-	buff := (*[1 << 30]byte)(unsafe.Pointer(buff0))
-	size := int(size0)
-	nbyt := 0
-	fill := func(value []byte) bool {
-		nbyt = len(value)
-		if 0 != size {
-			if nbyt > size {
-				return false
-			}
-			copy(buff[:size], value)
-		}
-		return true
-	}
-	errc := fsop.Getxattr(path, name, fill)
+	errc, rslt := fsop.Getxattr(path, name)
 	if 0 != errc {
 		return C.int(errc)
 	}
-	return C.int(nbyt)
+	if 0 != size0 {
+		if len(rslt) > int(size0) {
+			return -C.int(ERANGE)
+		}
+		buff := (*[1 << 30]byte)(unsafe.Pointer(buff0))
+		copy(buff[:size0], rslt)
+	}
+	return C.int(len(rslt))
 }
 
 //export hostListxattr