Add File.InnerFile() for safe unpacking.

fuse/api.go

@@ -140,6 +140,10 @@ type File interface {
 	// Called upon registering the filehandle in the inode.
 	SetInode(*Inode)
 
+	// Wrappers around other File implementations, should return
+	// the inner file here.
+	InnerFile() File 
+	
 	Read(*ReadIn, BufferPool) ([]byte, Status)
 	Write(*WriteIn, []byte) (written uint32, code Status)
 	Truncate(size uint64) Status

fuse/defaultfile.go

 package fuse
 
 import (
+	"log"
 	"os"
 )
 
+var _ = log.Println
+
 func (me *DefaultFile) SetInode(*Inode) {
 }
 
+func (me *DefaultFile) InnerFile() File {
+	return nil
+}
+
 func (me *DefaultFile) Read(*ReadIn, BufferPool) ([]byte, Status) {
 	return []byte(""), ENOSYS
 }

fuse/fsmount.go

@@ -133,7 +133,9 @@ func (me *fileSystemMount) registerFileHandle(node *Inode, dir rawDir, f File, f
 		f = withFlags.File
 	}
 
+	if b.WithFlags.File != nil {
 		b.WithFlags.File.SetInode(node)
+	}
 	node.openFiles = append(node.openFiles, b)
 	handle := me.openFiles.Register(&b.Handled, b)
 	return handle, b