Code shared from the Rust Playground

playground.rs

use std::path::PathBuf;
use std::ffi::CString;
use std::os::raw::c_char;

mod libnx {
    use std::os::raw::c_char;
    
    #[derive(Default)]
    pub struct FsFileSystem;
    
    pub unsafe fn fsOpenBisFileSystem(_fs: *mut FsFileSystem, _id: u32, _str: *const c_char) {}
    pub unsafe fn fsdevMountDevice(_name: *const c_char, _fs: FsFileSystem) {}
}

pub fn mount_sdk_fs(fs: &str) -> PathBuf {
    let mut bis_dev = libnx::FsFileSystem::default();
    let (bis_id, name, root) = match fs {
        "SystemContent" => (31, "System", PathBuf::from("System:/Contents/")),
        "UserContent" => (30, "User", PathBuf::from("User:/Contents/")),
        _ => panic!("FS not implemented!")
    };
    unsafe { libnx::fsOpenBisFileSystem(&mut bis_dev as *mut _, bis_id, &(0 as c_char) as *const _); }
    unsafe { libnx::fsdevMountDevice(CString::new(name).unwrap().as_ptr(), bis_dev); }
    root
}

pub struct SdkPath(PathBuf);

fn main() {
    let path = SdkPath(PathBuf::from("@SystemContent://test/asdfasdf.nca"));
    let mut segments: Vec<_> = path.0.ancestors().filter_map(|e| e.file_name()).map(|e| e.to_str().unwrap()).collect();
    let mut fs = segments.pop().unwrap()[1..].to_string();
    fs.pop();
    segments.reverse();
    
    let mut libnx_path = mount_sdk_fs(&fs);
    for segment in &segments {
        libnx_path.push(segment);
    }
    
    println!("path: {:?}", libnx_path)
}