fix: fix a potential out of bounds issue in fuse

We likely encountered a file that misreported its size. That or there was no bug
here and we hit an issue somewhere else. Regardless, there's no reason not to
simplify this code and this should fix the issue.

fixes #6765

fuse/readonly/readonly_unix.go

@@ -257,13 +257,15 @@ func (s *Node) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadR
 	if err != nil {
 		return err
 	}
-
-	buf := resp.Data[:min(req.Size, int(int64(r.Size())-req.Offset))]
+	// Data has a capacity of Size
+	buf := resp.Data[:int(req.Size)]
 	n, err := io.ReadFull(r, buf)
-	if err != nil && err != io.EOF {
+	resp.Data = buf[:n]
+	switch err {
+	case nil, io.EOF, io.ErrUnexpectedEOF:
+	default:
 		return err
 	}
-	resp.Data = resp.Data[:n]
 	lm["res_size"] = n
 	return nil // may be non-nil / not succeeded
 }
@@ -287,10 +289,3 @@ type roNode interface {
 }
 
 var _ roNode = (*Node)(nil)
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}