hijacking write call in Linux

hijacking-write.rs

use libc;
use std::ffi::CString;
use std::mem::transmute;
use std::os::raw::c_char;
use std::os::raw::c_int;
use std::os::raw::c_void;

#[no_mangle]
extern "C" fn strcmp(s1: *const c_char, s2: *const c_char) -> c_int {
    println!("strcmp");
    return 0;
}

#[no_mangle]
extern "C" fn write(fd: c_int, buf: *const c_void, count: libc::size_t) -> libc::ssize_t {
    let name = CString::new("write").expect("CString::new failed");
    let ptr = unsafe { libc::dlsym(libc::RTLD_NEXT, name.as_ptr()) };

    let msg = "hijacking\n";
    let handler: fn(c_int, *const c_void, libc::size_t) -> libc::ssize_t =
        unsafe { transmute(ptr) };
    //let b: c_void = unsafe { transmute(msg) };
    handler(fd, msg as *const _ as *const c_void, 10);
    return count as libc::ssize_t;
}