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: pipetest.rs
    path of file: ./repos/os_kernel_lab/user/src/bin
    
    the code of the file until where you have to start completion: #![no_std]
#![no_main]

#[macro_use]
extern crate user_lib;

use user_lib::{close, fork, pipe, read, wait, write};

static STR: &str = "Hello, world!";

#[no_mangle]
pub fn main() -> i32 {
    // create pipe
    let mut pipe_fd = [0usize; 2];
    pipe(&mut pipe_fd);
    // read end
    
    
pub fn main() -> i32 {
    // create pipe
    let mut pipe_fd = [0usize; 2];
    pipe(&mut pipe_fd);
    // read end
    assert_eq!(pipe_fd[0], 3);
    // write end
    assert_eq!(pipe_fd[1], 4);
    if fork() == 0 {
        // child process, read from parent
        // close write_end
        close(pipe_fd[1]);
        let mut buffer = [0u8; 32];
        let len_read = read(pipe_fd[0], &mut buffer) as usize;
        // close read_end
        close(pipe_fd[0]);
        assert_eq!(core::str::from_utf8(&buffer[..len_read]).unwrap(), STR);
        println!("Read OK, child process exited!");
        0
    } else {
        // parent process, write to child
        // close read end
        close(pipe_fd[0]);
        assert_eq!(write(pipe_fd[1], STR.as_bytes()), STR.len() as isize);
        // close write end
        close(pipe_fd[1]);
        let mut child_exit_code: i32 = 0;
        wait(&mut child_exit_code);
        assert_eq!(child_exit_code, 0);
        println!("pipetest passed!");
        0
    }
}