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 // ignore-msvc -- sprintf isn't a symbol in msvcrt? maybe a #define?
  12
  13 #![feature(libc, std_misc)]
  14
  15 extern crate libc;
  16
  17 use std::ffi::{CStr, CString};
  18 use libc::{c_char, c_int};
  19
  20
  21 extern {
  22     fn sprintf(s: *mut c_char, format: *const c_char, ...) -> c_int;
  23 }
  24
  25 unsafe fn check<T, F>(expected: &str, f: F) where F: FnOnce(*mut c_char) -> T {
  26     let mut x = [0 as c_char; 50];
  27     f(&mut x[0] as *mut c_char);
  28     assert_eq!(expected.as_bytes(), CStr::from_ptr(x.as_ptr()).to_bytes());
  29 }
  30
  31 pub fn main() {
  32
  33     unsafe {
  34         // Call with just the named parameter
  35         let c = CString::new(&b"Hello World\n"[..]).unwrap();
  36         check("Hello World\n", |s| sprintf(s, c.as_ptr()));
  37
  38         // Call with variable number of arguments
  39         let c = CString::new(&b"%d %f %c %s\n"[..]).unwrap();
  40         check("42 42.500000 a %d %f %c %s\n\n", |s| {
  41             sprintf(s, c.as_ptr(), 42, 42.5f64, 'a' as c_int, c.as_ptr());
  42         });
  43
  44         // Make a function pointer
  45         let x: unsafe extern fn(*mut c_char, *const c_char, ...) -> c_int = sprintf;
  46
  47         // A function that takes a function pointer
  48         unsafe fn call(fp: unsafe extern fn(*mut c_char, *const c_char, ...) -> c_int) {
  49             // Call with just the named parameter
  50             let c = CString::new(&b"Hello World\n"[..]).unwrap();
  51             check("Hello World\n", |s| fp(s, c.as_ptr()));
  52
  53             // Call with variable number of arguments
  54             let c = CString::new(&b"%d %f %c %s\n"[..]).unwrap();
  55             check("42 42.500000 a %d %f %c %s\n\n", |s| {
  56                 fp(s, c.as_ptr(), 42, 42.5f64, 'a' as c_int, c.as_ptr());
  57             });
  58         }
  59
  60         // Pass sprintf directly
  61         call(sprintf);
  62
  63         // Pass sprintf indirectly
  64         call(x);
  65     }
  66
  67 }