src/test/run-pass/variadic-ffi.rs

   1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11
  12 #![feature(libc, std_misc)]
  13
  14 extern crate libc;
  15
  16 use std::ffi::{CStr, CString};
  17 use libc::{c_char, c_int};
  18
  19
  20 extern {
  21     fn sprintf(s: *mut c_char, format: *const c_char, ...) -> c_int;
  22 }
  23
  24 unsafe fn check<T, F>(expected: &str, f: F) where F: FnOnce(*mut c_char) -> T {
  25     let mut x = [0 as c_char; 50];
  26     f(&mut x[0] as *mut c_char);
  27     assert_eq!(expected.as_bytes(), CStr::from_ptr(x.as_ptr()).to_bytes());
  28 }
  29
  30 pub fn main() {
  31
  32     unsafe {
  33         // Call with just the named parameter
  34         let c = CString::new(&b"Hello World\n"[..]).unwrap();
  35         check("Hello World\n", |s| sprintf(s, c.as_ptr()));
  36
  37         // Call with variable number of arguments
  38         let c = CString::new(&b"%d %f %c %s\n"[..]).unwrap();
  39         check("42 42.500000 a %d %f %c %s\n\n", |s| {
  40             sprintf(s, c.as_ptr(), 42, 42.5f64, 'a' as c_int, c.as_ptr());
  41         });
  42
  43         // Make a function pointer
  44         let x: unsafe extern fn(*mut c_char, *const c_char, ...) -> c_int = sprintf;
  45
  46         // A function that takes a function pointer
  47         unsafe fn call(p: unsafe extern fn(*mut c_char, *const c_char, ...) -> c_int) {
  48             // Call with just the named parameter
  49             let c = CString::new(&b"Hello World\n"[..]).unwrap();
  50             check("Hello World\n", |s| sprintf(s, c.as_ptr()));
  51
  52             // Call with variable number of arguments
  53             let c = CString::new(&b"%d %f %c %s\n"[..]).unwrap();
  54             check("42 42.500000 a %d %f %c %s\n\n", |s| {
  55                 sprintf(s, c.as_ptr(), 42, 42.5f64, 'a' as c_int, c.as_ptr());
  56             });
  57         }
  58
  59         // Pass sprintf directly
  60         call(sprintf);
  61
  62         // Pass sprintf indirectly
  63         call(x);
  64     }
  65
  66 }