From 09954c4bdecf0ca6da65776f176dc934ffced2b0 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Wed, 17 May 2023 23:26:56 +0200
Subject: fusefrontend: implement our own Access()

Not having Access() means go-fuse emulates it by looking at Getattr().
This works fine most of the time, but breaks down on sshfs, where
sshfs-benchmark.bash shows this:

	gocryptfs/tests$ ./sshfs-benchmark.bash nuetzlich.net
	working directory: /tmp/sshfs-benchmark.bash.JQC
	sshfs mounted: nuetzlich.net:/tmp -> sshfs.mnt
	gocryptfs mounted: sshfs.mnt/sshfs-benchmark.bash.Wrz/gocryptfs.crypt -> gocryptfs.mnt

	sshfs-benchmark.bash:    sshfs  gocryptfs-on-sshfs
	git init                  3.98                6.80
	rsync                     7.71               10.84
	rm -R                     4.30rm: descend into write-protected directory 'gocryptfs.mnt/git1'?

The go-fuse emulation gets it wrong here because sshfs reports
permissions but does not enforce them.

Implement it ourselves properly.
---
 internal/fusefrontend/node.go | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'internal')

diff --git a/internal/fusefrontend/node.go b/internal/fusefrontend/node.go
index 274123b..687a386 100644
--- a/internal/fusefrontend/node.go
+++ b/internal/fusefrontend/node.go
@@ -99,6 +99,17 @@ func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut)
 	return 0
 }
 
+func (n *Node) Access(ctx context.Context, mode uint32) syscall.Errno {
+	dirfd, cName, errno := n.prepareAtSyscallMyself()
+	if errno != 0 {
+		return errno
+	}
+	defer syscall.Close(dirfd)
+
+	err := syscallcompat.Faccessat(dirfd, cName, mode)
+	return fs.ToErrno(err)
+}
+
 // Unlink - FUSE call. Delete a file.
 //
 // Symlink-safe through use of Unlinkat().
-- 
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