lib.rs

#![feature(libc)]
extern crate libc;

use libc::*;
use std::ffi::{CStr, CString};

#[repr(C)]
pub struct SampleStruct {
   i: i32,
   b: bool,
   s: *const c_char
}

#[no_mangle]
pub extern fn create_sample_struct(s: *mut SampleStruct) {
    unsafe {
        (*s).i = 100;
        (*s).b = false;
        (*s).s = CString::new("hello").unwrap().into_raw();
    }
}