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// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//! tty related functionality
//!
use std::ffi::CStr;
use std::fs::File;
use std::os::unix::io::FromRawFd;
use std::os::unix::process::CommandExt;
use std::ptr;
use std::process::{Command, Stdio};
use libc::{self, winsize, c_int, pid_t, WNOHANG, SIGCHLD, TIOCSCTTY};
use term::SizeInfo;
use display::OnResize;
use config::{Config, Shell};
use cli::Options;
/// Process ID of child process
///
/// Necessary to put this in static storage for `sigchld` to have access
static mut PID: pid_t = 0;
/// Exit flag
///
/// Calling exit() in the SIGCHLD handler sometimes causes opengl to deadlock,
/// and the process hangs. Instead, this flag is set, and its status can be
/// checked via `process_should_exit`.
static mut SHOULD_EXIT: bool = false;
extern "C" fn sigchld(_a: c_int) {
let mut status: c_int = 0;
unsafe {
let p = libc::waitpid(PID, &mut status, WNOHANG);
if p < 0 {
die!("Waiting for pid {} failed: {}\n", PID, errno());
}
if PID == p {
SHOULD_EXIT = true;
}
}
}
pub fn process_should_exit() -> bool {
unsafe { SHOULD_EXIT }
}
/// Get the current value of errno
fn errno() -> c_int {
::errno::errno().0
}
/// Get raw fds for master/slave ends of a new pty
#[cfg(target_os = "linux")]
fn openpty(rows: u8, cols: u8) -> (c_int, c_int) {
let mut master: c_int = 0;
let mut slave: c_int = 0;
let win = winsize {
ws_row: libc::c_ushort::from(rows),
ws_col: libc::c_ushort::from(cols),
ws_xpixel: 0,
ws_ypixel: 0,
};
let res = unsafe {
libc::openpty(&mut master, &mut slave, ptr::null_mut(), ptr::null(), &win)
};
if res < 0 {
die!("openpty failed");
}
(master, slave)
}
#[cfg(any(target_os = "macos",target_os = "freebsd"))]
fn openpty(rows: u8, cols: u8) -> (c_int, c_int) {
let mut master: c_int = 0;
let mut slave: c_int = 0;
let mut win = winsize {
ws_row: libc::c_ushort::from(rows),
ws_col: libc::c_ushort::from(cols),
ws_xpixel: 0,
ws_ypixel: 0,
};
let res = unsafe {
libc::openpty(&mut master, &mut slave, ptr::null_mut(), ptr::null_mut(), &mut win)
};
if res < 0 {
die!("openpty failed");
}
(master, slave)
}
/// Really only needed on BSD, but should be fine elsewhere
fn set_controlling_terminal(fd: c_int) {
let res = unsafe {
// TIOSCTTY changes based on platform and the `ioctl` call is different
// based on architecture (32/64). So a generic cast is used to make sure
// there are no issues. To allow such a generic cast the clippy warning
// is disabled.
#[cfg_attr(feature = "clippy", allow(cast_lossless))]
libc::ioctl(fd, TIOCSCTTY as _, 0)
};
if res < 0 {
die!("ioctl TIOCSCTTY failed: {}", errno());
}
}
#[derive(Debug)]
struct Passwd<'a> {
name: &'a str,
passwd: &'a str,
uid: libc::uid_t,
gid: libc::gid_t,
gecos: &'a str,
dir: &'a str,
shell: &'a str,
}
/// Return a Passwd struct with pointers into the provided buf
///
/// # Unsafety
///
/// If `buf` is changed while `Passwd` is alive, bad thing will almost certainly happen.
fn get_pw_entry(buf: &mut [i8; 1024]) -> Passwd {
// Create zeroed passwd struct
let mut entry: libc::passwd = unsafe { ::std::mem::uninitialized() };
let mut res: *mut libc::passwd = ptr::null_mut();
// Try and read the pw file.
let uid = unsafe { libc::getuid() };
let status = unsafe {
libc::getpwuid_r(uid, &mut entry, buf.as_mut_ptr() as *mut _, buf.len(), &mut res)
};
if status < 0 {
die!("getpwuid_r failed");
}
if res.is_null() {
die!("pw not found");
}
// sanity check
assert_eq!(entry.pw_uid, uid);
// Build a borrowed Passwd struct
Passwd {
name: unsafe { CStr::from_ptr(entry.pw_name).to_str().unwrap() },
passwd: unsafe { CStr::from_ptr(entry.pw_passwd).to_str().unwrap() },
uid: entry.pw_uid,
gid: entry.pw_gid,
gecos: unsafe { CStr::from_ptr(entry.pw_gecos).to_str().unwrap() },
dir: unsafe { CStr::from_ptr(entry.pw_dir).to_str().unwrap() },
shell: unsafe { CStr::from_ptr(entry.pw_shell).to_str().unwrap() },
}
}
/// Create a new tty and return a handle to interact with it.
pub fn new<T: ToWinsize>(config: &Config, options: &Options, size: &T, window_id: Option<usize>) -> Pty {
let win = size.to_winsize();
let mut buf = [0; 1024];
let pw = get_pw_entry(&mut buf);
let (master, slave) = openpty(win.ws_row as _, win.ws_col as _);
let default_shell = &Shell::new(pw.shell);
let shell = config.shell()
.unwrap_or(default_shell);
let initial_command = options.command().unwrap_or(shell);
let mut builder = Command::new(initial_command.program());
for arg in initial_command.args() {
builder.arg(arg);
}
// Setup child stdin/stdout/stderr as slave fd of pty
// Ownership of fd is transferred to the Stdio structs and will be closed by them at the end of
// this scope. (It is not an issue that the fd is closed three times since File::drop ignores
// error on libc::close.)
builder.stdin(unsafe { Stdio::from_raw_fd(slave) });
builder.stderr(unsafe { Stdio::from_raw_fd(slave) });
builder.stdout(unsafe { Stdio::from_raw_fd(slave) });
// Setup environment
builder.env("LOGNAME", pw.name);
builder.env("USER", pw.name);
builder.env("SHELL", shell.program());
builder.env("HOME", pw.dir);
builder.env("TERM", "xterm-256color"); // default term until we can supply our own
if let Some(window_id) = window_id {
builder.env("WINDOWID", format!("{}", window_id));
}
for (key, value) in config.env().iter() {
builder.env(key, value);
}
builder.before_exec(move || {
// Create a new process group
unsafe {
let err = libc::setsid();
if err == -1 {
die!("Failed to set session id: {}", errno());
}
}
set_controlling_terminal(slave);
// No longer need slave/master fds
unsafe {
libc::close(slave);
libc::close(master);
}
unsafe {
libc::signal(libc::SIGCHLD, libc::SIG_DFL);
libc::signal(libc::SIGHUP, libc::SIG_DFL);
libc::signal(libc::SIGINT, libc::SIG_DFL);
libc::signal(libc::SIGQUIT, libc::SIG_DFL);
libc::signal(libc::SIGTERM, libc::SIG_DFL);
libc::signal(libc::SIGALRM, libc::SIG_DFL);
}
Ok(())
|