file_io.alu

use std::fs::{File, Path};
use std::io::{Error, Readable, Writable};

fn copy<S: Readable<S>, D: Writable<D>>(
    src: &mut S,
    dst: &mut D
) -> Result<(), Error> {
    let buf: [u8; 1024];

    loop {
        let n = src.read(&buf)?;
        if n == 0 {
            break;
        }
        dst.write_all(buf[0..n])?;
    }

    dst.flush()
}

fn copy_file(src: Path, dst: Path) -> Result<(), Error> {
    let src = File::open(src)?;
    defer src.close();

    let dst = File::create(dst)?;
    defer dst.close();

    copy(&src, &dst)?;

    Result::ok(())
}

fn main() -> i32 {
    let ret = copy_file(
        Path::new("/proc/mounts"),
        Path::new("./mounts.txt")
    );

    if ret.is_err() {
        eprintln!("failed: {}", ret.unwrap_err());
        1
    } else {
        0
    }
}