We use our own small wrappers for these syscalls, built on top of Rust's libc crate. All our wrappers live here:

https://github.com/maelstrom-software/maelstrom/blob/main/cr...

For bind mounts, you want to look at open_tree and move_mount. For "regular" mounts, you want to look at fsopen, fsconfig, fsmount, and move_mount.

I found this video very useful: https://www.youtube.com/watch?v=gMWKFPnmJSc