// Copyright 2020 Alyssa Ross
//
// This file is part of pushmail.
//
// pushmail is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// pushmail is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with pushmail; if not, write to the Free Software Foundation,
// Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// Linking pushmail statically or dynamically with other modules is
// making a combined work based on pushmail.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// In addition, as a special exception, the copyright holders of
// pushmail give you permission to combine pushmail with free software
// programs or libraries that are released under the GNU LGPL and with
// code included in the standard release of OpenSSL under the OpenSSL
// License or the Original SSLeay License (or modified versions of
// such code, with unchanged license).  You may copy and distribute
// such a system following the terms of the GNU GPL for pushmail and
// the licenses of the other code concerned, provided that you include
// the source code of that other code when and as the GNU GPL requires
// distribution of source code.
//
// Note that people who make modified versions of pushmail are not
// obligated to grant this special exception for their modified
// versions; it is their choice whether to do so.  The GNU General
// Public License gives permission to release a modified version
// without this exception; this exception also makes it possible to
// release a modified version which carries forward this exception.

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)
}