[minor] The way AllowOther is handled is confusing

[0x53A]

As a preface, I don't know much about how fuse works.

I created a new rust project, referenced this crate and copied the simple example into main.rs. So far so good.

On startup, it fails with

fusermount3: option allow_other only allowed if 'user_allow_other' is set in /etc/fuse.conf

Of course, the simple option would be to do that, but instead I'm looking for why 'allow_other ' is set at all, because it's not done by me.

Running it with verbose logging shows:

[2024-11-25T23:20:03.185848941Z WARN fuser::session] Given auto_unmount without allow_root or allow_other; adding allow_other, with userspace permission handling

And in session I find:

        // If AutoUnmount is requested, but not AllowRoot or AllowOther we enforce the ACL
        // ourself and implicitly set AllowOther because fusermount needs allow_root or allow_other
        // to handle the auto_unmount option
        let (file, mount) = if options.contains(&MountOption::AutoUnmount)
            && !(options.contains(&MountOption::AllowRoot)
                || options.contains(&MountOption::AllowOther))
        {
            warn!("Given auto_unmount without allow_root or allow_other; adding allow_other, with userspace permission handling");
            let mut modified_options = options.to_vec();
            modified_options.push(MountOption::AllowOther);
            Mount::new(mountpoint, &modified_options)?
        } else {
            Mount::new(mountpoint, options)?
        };

Aha, I think, and add AllowRoot in main.rs.

And ... it still fails with the same error???

A little bit of digging later, I see, in mountoptions.rs:

// Format option to be passed to libfuse or kernel
pub fn option_to_string(option: &MountOption) -> String {
    match option {
        // [...]
        MountOption::AllowOther => "allow_other".to_string(),
        // AllowRoot is implemented by allowing everyone access and then restricting to
        // root + owner within fuser
        MountOption::AllowRoot => "allow_other".to_string(),
        // [...]
    }
}

So the only option (besides setting 'user_allow_other' in /etc/fuse.conf) is to remove AutoUnmount from main.rs. Which is added unconditionally, despite AllowOther being behind a check of fuse_allow_other_enabled.

Of course this is a trivial issue, just wanted to report it. please feel free to close it.