fs: fix unconditional FileGetattrer cast

hanwen · hanwen · commit 531a68551e40 · 2024-09-23T09:58:18.000+02:00
LoopbackNode assumes the passed-in file is a FileGetattrer. This is
true in the common case, but not in general.

Change-Id: Iff38d6cb80666c3107ffc65b1034b68641a79d21
diff --git a/fs/loopback.go b/fs/loopback.go
@@ -364,7 +364,9 @@ var _ = (NodeGetattrer)((*LoopbackNode)(nil))
 
 func (n *LoopbackNode) Getattr(ctx context.Context, f FileHandle, out *fuse.AttrOut) syscall.Errno {
 	if f != nil {
-		return f.(FileGetattrer).Getattr(ctx, out)
+		if fga, ok := f.(FileGetattrer); ok {
+			return fga.Getattr(ctx, out)
+		}
 	}
 
 	p := n.path()

Original file line number	Diff line number	Diff line change
`@@ -364,7 +364,9 @@ var _ = (NodeGetattrer)((*LoopbackNode)(nil))`
`364`	`364`
`365`	`365`	`func (n LoopbackNode) Getattr(ctx context.Context, f FileHandle, out fuse.AttrOut) syscall.Errno {`
`366`	`366`	`if f != nil {`
`367`		`- return f.(FileGetattrer).Getattr(ctx, out)`
	`367`	`+ if fga, ok := f.(FileGetattrer); ok {`
	`368`	`+ return fga.Getattr(ctx, out)`
	`369`	`+ }`
`368`	`370`	`}`
`369`	`371`
`370`	`372`	`p := n.path()`