You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: last_char_is.rs
    path of file: ./repos/rustybox/libbb
    
    the code of the file until where you have to start completion: use crate::librb::size_t;
use libc;
extern "C" {
  #[no_mangle]
  fn strlen(__s: *const libc::c_ch
    
pub unsafe fn last_char_is(mut s: *const libc::c_char, mut c: libc::c_int) -> *mut libc::c_char {
  if !s.is_null() && *s as libc::c_int != 0 {
    let mut sz: size_t = strlen(s).wrapping_sub(1i32 as libc::c_ulong);
    s = s.offset(sz as isize);
    if *s as libc::c_uchar as libc::c_int == c {
      return s as *mut libc::c_char;
    }
  }
  return std::ptr::null_mut::<libc::c_char>();
}