567 lines
20 KiB
Rust
567 lines
20 KiB
Rust
// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![allow(non_snake_case)]
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use prelude::v1::*;
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use os::unix::prelude::*;
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use collections::HashMap;
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use env;
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use ffi::{OsString, OsStr, CString, CStr};
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use fmt;
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use io::{self, Error, ErrorKind};
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use libc::{self, pid_t, c_void, c_int, gid_t, uid_t};
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use ptr;
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use sys::fd::FileDesc;
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use sys::fs::{File, OpenOptions};
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use sys::pipe::AnonPipe;
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use sys::{self, cvt, cvt_r};
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////////////////////////////////////////////////////////////////////////////////
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// Command
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////////////////////////////////////////////////////////////////////////////////
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#[derive(Clone)]
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pub struct Command {
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pub program: CString,
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pub args: Vec<CString>,
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pub env: Option<HashMap<OsString, OsString>>,
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pub cwd: Option<CString>,
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pub uid: Option<uid_t>,
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pub gid: Option<gid_t>,
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pub session_leader: bool,
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}
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impl Command {
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pub fn new(program: &OsStr) -> Command {
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Command {
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program: os2c(program),
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args: Vec::new(),
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env: None,
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cwd: None,
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uid: None,
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gid: None,
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session_leader: false,
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}
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}
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pub fn arg(&mut self, arg: &OsStr) {
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self.args.push(os2c(arg));
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}
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pub fn args<'a, I: Iterator<Item = &'a OsStr>>(&mut self, args: I) {
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self.args.extend(args.map(os2c));
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}
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fn init_env_map(&mut self) {
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if self.env.is_none() {
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self.env = Some(env::vars_os().collect());
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}
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}
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pub fn env(&mut self, key: &OsStr, val: &OsStr) {
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self.init_env_map();
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self.env.as_mut().unwrap().insert(key.to_os_string(), val.to_os_string());
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}
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pub fn env_remove(&mut self, key: &OsStr) {
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self.init_env_map();
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self.env.as_mut().unwrap().remove(&key.to_os_string());
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}
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pub fn env_clear(&mut self) {
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self.env = Some(HashMap::new())
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}
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pub fn cwd(&mut self, dir: &OsStr) {
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self.cwd = Some(os2c(dir));
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}
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}
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fn os2c(s: &OsStr) -> CString {
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CString::new(s.as_bytes()).unwrap()
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}
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////////////////////////////////////////////////////////////////////////////////
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// Processes
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////////////////////////////////////////////////////////////////////////////////
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/// Unix exit statuses
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#[derive(PartialEq, Eq, Clone, Copy, Debug)]
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pub struct ExitStatus(c_int);
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#[cfg(any(target_os = "linux", target_os = "android",
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target_os = "nacl", target_os = "solaris"))]
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mod status_imp {
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pub fn WIFEXITED(status: i32) -> bool { (status & 0xff) == 0 }
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pub fn WEXITSTATUS(status: i32) -> i32 { (status >> 8) & 0xff }
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pub fn WTERMSIG(status: i32) -> i32 { status & 0x7f }
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}
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#[cfg(any(target_os = "macos",
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target_os = "ios",
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target_os = "freebsd",
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target_os = "dragonfly",
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target_os = "bitrig",
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target_os = "netbsd",
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target_os = "openbsd"))]
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mod status_imp {
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pub fn WIFEXITED(status: i32) -> bool { (status & 0x7f) == 0 }
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pub fn WEXITSTATUS(status: i32) -> i32 { status >> 8 }
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pub fn WTERMSIG(status: i32) -> i32 { status & 0o177 }
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}
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impl ExitStatus {
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fn exited(&self) -> bool {
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status_imp::WIFEXITED(self.0)
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}
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pub fn success(&self) -> bool {
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self.code() == Some(0)
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}
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pub fn code(&self) -> Option<i32> {
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if self.exited() {
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Some(status_imp::WEXITSTATUS(self.0))
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} else {
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None
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}
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}
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pub fn signal(&self) -> Option<i32> {
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if !self.exited() {
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Some(status_imp::WTERMSIG(self.0))
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} else {
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None
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}
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}
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}
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impl fmt::Display for ExitStatus {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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if let Some(code) = self.code() {
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write!(f, "exit code: {}", code)
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} else {
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let signal = self.signal().unwrap();
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write!(f, "signal: {}", signal)
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}
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}
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}
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/// The unique id of the process (this should never be negative).
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pub struct Process {
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pid: pid_t
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}
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pub enum Stdio {
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Inherit,
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None,
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Raw(c_int),
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}
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pub type RawStdio = FileDesc;
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const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX";
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impl Process {
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pub unsafe fn kill(&self) -> io::Result<()> {
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try!(cvt(libc::kill(self.pid, libc::SIGKILL)));
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Ok(())
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}
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pub fn spawn(cfg: &Command,
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in_fd: Stdio,
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out_fd: Stdio,
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err_fd: Stdio) -> io::Result<Process> {
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let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null());
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let (envp, _a, _b) = make_envp(cfg.env.as_ref());
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let (argv, _a) = make_argv(&cfg.program, &cfg.args);
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let (input, output) = try!(sys::pipe::anon_pipe());
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let pid = unsafe {
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match libc::fork() {
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0 => {
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drop(input);
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Process::child_after_fork(cfg, output, argv, envp, dirp,
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in_fd, out_fd, err_fd)
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}
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n if n < 0 => return Err(Error::last_os_error()),
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n => n,
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}
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};
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let p = Process{ pid: pid };
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drop(output);
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let mut bytes = [0; 8];
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// loop to handle EINTR
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loop {
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match input.read(&mut bytes) {
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Ok(0) => return Ok(p),
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Ok(8) => {
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assert!(combine(CLOEXEC_MSG_FOOTER) == combine(&bytes[4.. 8]),
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"Validation on the CLOEXEC pipe failed: {:?}", bytes);
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let errno = combine(&bytes[0.. 4]);
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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return Err(Error::from_raw_os_error(errno))
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}
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Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
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Err(e) => {
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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panic!("the CLOEXEC pipe failed: {:?}", e)
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},
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Ok(..) => { // pipe I/O up to PIPE_BUF bytes should be atomic
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assert!(p.wait().is_ok(),
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"wait() should either return Ok or panic");
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panic!("short read on the CLOEXEC pipe")
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}
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}
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}
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fn combine(arr: &[u8]) -> i32 {
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let a = arr[0] as u32;
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let b = arr[1] as u32;
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let c = arr[2] as u32;
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let d = arr[3] as u32;
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((a << 24) | (b << 16) | (c << 8) | (d << 0)) as i32
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}
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}
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// And at this point we've reached a special time in the life of the
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// child. The child must now be considered hamstrung and unable to
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// do anything other than syscalls really. Consider the following
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// scenario:
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//
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// 1. Thread A of process 1 grabs the malloc() mutex
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// 2. Thread B of process 1 forks(), creating thread C
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// 3. Thread C of process 2 then attempts to malloc()
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// 4. The memory of process 2 is the same as the memory of
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// process 1, so the mutex is locked.
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//
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// This situation looks a lot like deadlock, right? It turns out
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// that this is what pthread_atfork() takes care of, which is
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// presumably implemented across platforms. The first thing that
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// threads to *before* forking is to do things like grab the malloc
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// mutex, and then after the fork they unlock it.
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//
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// Despite this information, libnative's spawn has been witnessed to
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// deadlock on both OSX and FreeBSD. I'm not entirely sure why, but
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// all collected backtraces point at malloc/free traffic in the
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// child spawned process.
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//
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// For this reason, the block of code below should contain 0
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// invocations of either malloc of free (or their related friends).
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//
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// As an example of not having malloc/free traffic, we don't close
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// this file descriptor by dropping the FileDesc (which contains an
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// allocation). Instead we just close it manually. This will never
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// have the drop glue anyway because this code never returns (the
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// child will either exec() or invoke libc::exit)
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unsafe fn child_after_fork(cfg: &Command,
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mut output: AnonPipe,
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argv: *const *const libc::c_char,
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envp: *const libc::c_void,
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dirp: *const libc::c_char,
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in_fd: Stdio,
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out_fd: Stdio,
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err_fd: Stdio) -> ! {
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fn fail(output: &mut AnonPipe) -> ! {
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let errno = sys::os::errno() as u32;
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let bytes = [
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(errno >> 24) as u8,
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(errno >> 16) as u8,
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(errno >> 8) as u8,
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(errno >> 0) as u8,
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CLOEXEC_MSG_FOOTER[0], CLOEXEC_MSG_FOOTER[1],
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CLOEXEC_MSG_FOOTER[2], CLOEXEC_MSG_FOOTER[3]
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];
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// pipe I/O up to PIPE_BUF bytes should be atomic, and then we want
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// to be sure we *don't* run at_exit destructors as we're being torn
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// down regardless
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assert!(output.write(&bytes).is_ok());
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unsafe { libc::_exit(1) }
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}
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// Make sure that the source descriptors are not an stdio descriptor,
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// otherwise the order which we set the child's descriptors may blow
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// away a descriptor which we are hoping to save. For example,
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// suppose we want the child's stderr to be the parent's stdout, and
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// the child's stdout to be the parent's stderr. No matter which we
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// dup first, the second will get overwritten prematurely.
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let maybe_migrate = |src: Stdio, output: &mut AnonPipe| {
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match src {
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Stdio::Raw(fd @ libc::STDIN_FILENO) |
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Stdio::Raw(fd @ libc::STDOUT_FILENO) |
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Stdio::Raw(fd @ libc::STDERR_FILENO) => {
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let fd = match cvt_r(|| libc::dup(fd)) {
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Ok(fd) => fd,
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Err(_) => fail(output),
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};
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let fd = FileDesc::new(fd);
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fd.set_cloexec();
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Stdio::Raw(fd.into_raw())
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},
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s @ Stdio::None |
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s @ Stdio::Inherit |
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s @ Stdio::Raw(_) => s,
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}
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};
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let setup = |src: Stdio, dst: c_int| {
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match src {
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Stdio::Inherit => true,
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Stdio::Raw(fd) => cvt_r(|| libc::dup2(fd, dst)).is_ok(),
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// If a stdio file descriptor is set to be ignored, we open up
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// /dev/null into that file descriptor. Otherwise, the first
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// file descriptor opened up in the child would be numbered as
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// one of the stdio file descriptors, which is likely to wreak
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// havoc.
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Stdio::None => {
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let mut opts = OpenOptions::new();
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opts.read(dst == libc::STDIN_FILENO);
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opts.write(dst != libc::STDIN_FILENO);
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let devnull = CStr::from_ptr(b"/dev/null\0".as_ptr()
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as *const _);
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if let Ok(f) = File::open_c(devnull, &opts) {
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cvt_r(|| libc::dup2(f.fd().raw(), dst)).is_ok()
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} else {
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false
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}
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}
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}
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};
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// Make sure we migrate all source descriptors before
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// we start overwriting them
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let in_fd = maybe_migrate(in_fd, &mut output);
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let out_fd = maybe_migrate(out_fd, &mut output);
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let err_fd = maybe_migrate(err_fd, &mut output);
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if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
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if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
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if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
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if let Some(u) = cfg.gid {
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if libc::setgid(u as libc::gid_t) != 0 {
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fail(&mut output);
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}
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}
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if let Some(u) = cfg.uid {
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// When dropping privileges from root, the `setgroups` call
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// will remove any extraneous groups. If we don't call this,
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// then even though our uid has dropped, we may still have
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// groups that enable us to do super-user things. This will
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// fail if we aren't root, so don't bother checking the
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// return value, this is just done as an optimistic
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// privilege dropping function.
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let _ = libc::setgroups(0, ptr::null());
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if libc::setuid(u as libc::uid_t) != 0 {
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fail(&mut output);
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}
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}
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if cfg.session_leader {
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// Don't check the error of setsid because it fails if we're the
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// process leader already. We just forked so it shouldn't return
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// error, but ignore it anyway.
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let _ = libc::setsid();
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}
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if !dirp.is_null() && libc::chdir(dirp) == -1 {
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fail(&mut output);
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}
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if !envp.is_null() {
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*sys::os::environ() = envp as *const _;
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}
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#[cfg(not(target_os = "nacl"))]
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unsafe fn reset_signal_handling(output: &mut AnonPipe) {
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use mem;
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// Reset signal handling so the child process starts in a
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// standardized state. libstd ignores SIGPIPE, and signal-handling
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// libraries often set a mask. Child processes inherit ignored
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// signals and the signal mask from their parent, but most
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// UNIX programs do not reset these things on their own, so we
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// need to clean things up now to avoid confusing the program
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// we're about to run.
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let mut set: libc::sigset_t = mem::uninitialized();
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if libc::sigemptyset(&mut set) != 0 ||
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libc::pthread_sigmask(libc::SIG_SETMASK, &set, ptr::null_mut()) != 0 ||
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libc::signal(
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libc::SIGPIPE, mem::transmute(libc::SIG_DFL)
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) == mem::transmute(libc::SIG_ERR)
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{
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fail(output);
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}
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}
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#[cfg(target_os = "nacl")]
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unsafe fn reset_signal_handling(_output: &mut AnonPipe) {
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// NaCl has no signal support.
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}
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reset_signal_handling(&mut output);
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let _ = libc::execvp(*argv, argv);
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fail(&mut output)
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}
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pub fn id(&self) -> u32 {
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self.pid as u32
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}
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pub fn wait(&self) -> io::Result<ExitStatus> {
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let mut status = 0 as c_int;
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try!(cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) }));
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Ok(ExitStatus(status))
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}
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pub fn try_wait(&self) -> Option<ExitStatus> {
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let mut status = 0 as c_int;
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match cvt_r(|| unsafe {
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libc::waitpid(self.pid, &mut status, libc::WNOHANG)
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}) {
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Ok(0) => None,
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Ok(n) if n == self.pid => Some(ExitStatus(status)),
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Ok(n) => panic!("unknown pid: {}", n),
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Err(e) => panic!("unknown waitpid error: {}", e),
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}
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}
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}
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fn make_argv(prog: &CString, args: &[CString])
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-> (*const *const libc::c_char, Vec<*const libc::c_char>)
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{
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let mut ptrs: Vec<*const libc::c_char> = Vec::with_capacity(args.len()+1);
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// Convert the CStrings into an array of pointers. Also return the
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// vector that owns the raw pointers, to ensure they live long
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// enough.
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ptrs.push(prog.as_ptr());
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ptrs.extend(args.iter().map(|tmp| tmp.as_ptr()));
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// Add a terminating null pointer (required by libc).
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ptrs.push(ptr::null());
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(ptrs.as_ptr(), ptrs)
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}
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fn make_envp(env: Option<&HashMap<OsString, OsString>>)
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-> (*const c_void, Vec<Vec<u8>>, Vec<*const libc::c_char>)
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{
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// On posixy systems we can pass a char** for envp, which is a
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// null-terminated array of "k=v\0" strings. As with make_argv, we
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// return two vectors that own the data to ensure that they live
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// long enough.
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if let Some(env) = env {
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let mut tmps = Vec::with_capacity(env.len());
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for pair in env {
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let mut kv = Vec::new();
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kv.extend_from_slice(pair.0.as_bytes());
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kv.push('=' as u8);
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kv.extend_from_slice(pair.1.as_bytes());
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kv.push(0); // terminating null
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tmps.push(kv);
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}
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let mut ptrs: Vec<*const libc::c_char> =
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tmps.iter()
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.map(|tmp| tmp.as_ptr() as *const libc::c_char)
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.collect();
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ptrs.push(ptr::null());
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(ptrs.as_ptr() as *const _, tmps, ptrs)
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} else {
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(ptr::null(), Vec::new(), Vec::new())
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use prelude::v1::*;
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|
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use ffi::OsStr;
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use mem;
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use ptr;
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use libc;
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use sys::{self, cvt};
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|
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|
macro_rules! t {
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|
($e:expr) => {
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|
match $e {
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|
Ok(t) => t,
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|
Err(e) => panic!("received error for `{}`: {}", stringify!($e), e),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(not(target_os = "android"))]
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|
extern {
|
|
#[cfg_attr(target_os = "netbsd", link_name = "__sigaddset14")]
|
|
fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int;
|
|
}
|
|
|
|
#[cfg(target_os = "android")]
|
|
unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
|
|
use slice;
|
|
|
|
let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<libc::sigset_t>());
|
|
let bit = (signum - 1) as usize;
|
|
raw[bit / 8] |= 1 << (bit % 8);
|
|
return 0;
|
|
}
|
|
|
|
// See #14232 for more information, but it appears that signal delivery to a
|
|
// newly spawned process may just be raced in the OSX, so to prevent this
|
|
// test from being flaky we ignore it on OSX.
|
|
#[test]
|
|
#[cfg_attr(target_os = "macos", ignore)]
|
|
#[cfg_attr(target_os = "nacl", ignore)] // no signals on NaCl.
|
|
fn test_process_mask() {
|
|
unsafe {
|
|
// Test to make sure that a signal mask does not get inherited.
|
|
let cmd = Command::new(OsStr::new("cat"));
|
|
let (stdin_read, stdin_write) = t!(sys::pipe::anon_pipe());
|
|
let (stdout_read, stdout_write) = t!(sys::pipe::anon_pipe());
|
|
|
|
let mut set: libc::sigset_t = mem::uninitialized();
|
|
let mut old_set: libc::sigset_t = mem::uninitialized();
|
|
t!(cvt(libc::sigemptyset(&mut set)));
|
|
t!(cvt(sigaddset(&mut set, libc::SIGINT)));
|
|
t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set, &mut old_set)));
|
|
|
|
let cat = t!(Process::spawn(&cmd, Stdio::Raw(stdin_read.raw()),
|
|
Stdio::Raw(stdout_write.raw()),
|
|
Stdio::None));
|
|
drop(stdin_read);
|
|
drop(stdout_write);
|
|
|
|
t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &old_set,
|
|
ptr::null_mut())));
|
|
|
|
t!(cvt(libc::kill(cat.id() as libc::pid_t, libc::SIGINT)));
|
|
// We need to wait until SIGINT is definitely delivered. The
|
|
// easiest way is to write something to cat, and try to read it
|
|
// back: if SIGINT is unmasked, it'll get delivered when cat is
|
|
// next scheduled.
|
|
let _ = stdin_write.write(b"Hello");
|
|
drop(stdin_write);
|
|
|
|
// Either EOF or failure (EPIPE) is okay.
|
|
let mut buf = [0; 5];
|
|
if let Ok(ret) = stdout_read.read(&mut buf) {
|
|
assert!(ret == 0);
|
|
}
|
|
|
|
t!(cat.wait());
|
|
}
|
|
}
|
|
}
|