execv.rs

mod ffi {
    use libc::{c_int, c_char};

    extern {
        pub fn setns(fd: c_int, nstype: c_int) -> c_int;
        pub fn execvp(path: *const c_char, arg: *const *const c_char) -> c_int;
    }
}


fn exec(args: &[String]) -> Result<(), String> {
    let mut cargs = Vec::new();
    let mut tmp = Vec::new();
    for arg in args.iter() {
        let s: &str = arg;
        let p = CString::new(s).unwrap();
        tmp.push(p);
        cargs.push(tmp[tmp.len()-1].as_ptr());
    }
    cargs.push(ptr::null());

    let ret = unsafe {
        ffi::execvp(cargs[0], cargs.as_ptr())
    };
    Err(format!("execv error: {}", ret))
}

example of an FFI call in Rust, for execvp and setns.