use std::io::prelude::*;
use std::io::{ErrorKind, self};
use std::ffi::OsString;
use std::os::unix::prelude::*;
use libc::{gethostname, _SC_HOST_NAME_MAX};

pub fn copy_stream(src: &mut dyn Read, dst: &mut dyn Write) -> io::Result<()> {
    let mut buf = vec![0; 65536];
    loop {
        match src.read(&mut buf) {
            Ok(0) => return Ok(()),
            Ok(len) => dst.write_all(&buf[..len])?,
            Err(e) if e.kind() == ErrorKind::Interrupted => continue,
            Err(e) => return Err(e),
        }
    }
}

pub fn hostname() -> OsString {
    let mut bytes = vec![0; _SC_HOST_NAME_MAX as usize + 2];

    if unsafe { gethostname(bytes.as_mut_ptr(), bytes.len()) } == -1 {
        panic!("gethostname failed: {}", std::io::Error::last_os_error());
    }

    if bytes[_SC_HOST_NAME_MAX as usize + 1] != 0 {
        panic!("hostname longer than HOST_NAME_MAX");
    }

    let bytes: Vec<_> = bytes
        .into_iter()
        .take_while(|b| *b != 0)
        .map(|b| b as u8)
        .collect();
    OsString::from_vec(bytes)
}