Function fexecve 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn fexecve(
    fd: c_int,
    argv: *const *mut c_char,
    envp: *const *mut c_char,
) -> c_int

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/fexecve.html.