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Add std::process

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Per [RFC 579](https://github.com/rust-lang/rfcs/pull/579), this commit
adds a new `std::process` module. This module is largely based on the
existing `std::old_io::process` module, but refactors the API to use
`OsStr` and other new standards set out by IO reform.

The existing module is not yet deprecated, to allow for the new API to
get a bit of testing before a mass migration to it.
This commit is contained in:
Aaron Turon 2015-02-06 09:42:57 -08:00
parent 39b463f153
commit 4175f1ce2f
16 changed files with 2051 additions and 36 deletions
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446
src/libstd/sys/unix/process2.rs Normal file
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// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use prelude::v1::*;
use collections::HashMap;
use collections::hash_map::Hasher;
use env;
use ffi::{OsString, OsStr, CString};
use fmt;
use hash::Hash;
use io::{self, Error, ErrorKind};
use libc::{self, pid_t, c_void, c_int, gid_t, uid_t};
use mem;
use old_io;
use os;
use os::unix::OsStrExt;
use ptr;
use sync::mpsc::{channel, Sender, Receiver};
use sys::pipe2::AnonPipe;
use sys::{self, retry, c, wouldblock, set_nonblocking, ms_to_timeval, cvt};
use sys_common::AsInner;
////////////////////////////////////////////////////////////////////////////////
// Command
////////////////////////////////////////////////////////////////////////////////
#[derive(Clone)]
pub struct Command {
pub program: CString,
pub args: Vec<CString>,
pub env: Option<HashMap<OsString, OsString>>,
pub cwd: Option<CString>,
pub uid: Option<uid_t>,
pub gid: Option<gid_t>,
pub detach: bool, // not currently exposed in std::process
}
impl Command {
pub fn new(program: &OsStr) -> Command {
Command {
program: program.to_cstring(),
args: Vec::new(),
env: None,
cwd: None,
uid: None,
gid: None,
detach: false,
}
}
pub fn arg(&mut self, arg: &OsStr) {
self.args.push(arg.to_cstring())
}
pub fn args<'a, I: Iterator<Item = &'a OsStr>>(&mut self, args: I) {
self.args.extend(args.map(OsStrExt::to_cstring))
}
fn init_env_map(&mut self) {
if self.env.is_none() {
self.env = Some(env::vars_os().collect());
}
}
pub fn env(&mut self, key: &OsStr, val: &OsStr) {
self.init_env_map();
self.env.as_mut().unwrap().insert(key.to_os_string(), val.to_os_string());
}
pub fn env_remove(&mut self, key: &OsStr) {
self.init_env_map();
self.env.as_mut().unwrap().remove(&key.to_os_string());
}
pub fn env_clear(&mut self) {
self.env = Some(HashMap::new())
}
pub fn cwd(&mut self, dir: &OsStr) {
self.cwd = Some(dir.to_cstring())
}
}
////////////////////////////////////////////////////////////////////////////////
// Processes
////////////////////////////////////////////////////////////////////////////////
/// Unix exit statuses
#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub enum ExitStatus {
/// Normal termination with an exit code.
Code(i32),
/// Termination by signal, with the signal number.
///
/// Never generated on Windows.
Signal(i32),
}
impl ExitStatus {
pub fn success(&self) -> bool {
*self == ExitStatus::Code(0)
}
pub fn code(&self) -> Option<i32> {
match *self {
ExitStatus::Code(c) => Some(c),
_ => None
}
}
}
impl fmt::Display for ExitStatus {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
ExitStatus::Code(code) => write!(f, "exit code: {}", code),
ExitStatus::Signal(code) => write!(f, "signal: {}", code),
}
}
}
/// The unique id of the process (this should never be negative).
pub struct Process {
pid: pid_t
}
const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX";
impl Process {
pub fn id(&self) -> pid_t {
self.pid
}
pub unsafe fn kill(&self) -> io::Result<()> {
try!(cvt(libc::funcs::posix88::signal::kill(self.pid, libc::SIGKILL)));
Ok(())
}
pub fn spawn(cfg: &Command,
in_fd: Option<AnonPipe>, out_fd: Option<AnonPipe>, err_fd: Option<AnonPipe>)
-> io::Result<Process>
{
use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp};
use libc::funcs::bsd44::getdtablesize;
mod rustrt {
extern {
pub fn rust_unset_sigprocmask();
}
}
unsafe fn set_cloexec(fd: c_int) {
let ret = c::ioctl(fd, c::FIOCLEX);
assert_eq!(ret, 0);
}
let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null());
with_envp(cfg.env.as_ref(), |envp: *const c_void| {
with_argv(&cfg.program, &cfg.args, |argv: *const *const libc::c_char| unsafe {
let (input, mut output) = try!(sys::pipe2::anon_pipe());
// We may use this in the child, so perform allocations before the
// fork
let devnull = b"/dev/null\0";
set_cloexec(output.raw());
let pid = fork();
if pid < 0 {
return Err(Error::last_os_error())
} else if pid > 0 {
#[inline]
fn combine(arr: &[u8]) -> i32 {
let a = arr[0] as u32;
let b = arr[1] as u32;
let c = arr[2] as u32;
let d = arr[3] as u32;
((a << 24) | (b << 16) | (c << 8) | (d << 0)) as i32
}
let p = Process{ pid: pid };
drop(output);
let mut bytes = [0; 8];
// loop to handle EINTER
loop {
match input.read(&mut bytes) {
Ok(8) => {
assert!(combine(CLOEXEC_MSG_FOOTER) == combine(&bytes[4.. 8]),
"Validation on the CLOEXEC pipe failed: {:?}", bytes);
let errno = combine(&bytes[0.. 4]);
assert!(p.wait().is_ok(),
"wait() should either return Ok or panic");
return Err(Error::from_os_error(errno))
}
Ok(0) => return Ok(p),
Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
Err(e) => {
assert!(p.wait().is_ok(),
"wait() should either return Ok or panic");
panic!("the CLOEXEC pipe failed: {:?}", e)
},
Ok(..) => { // pipe I/O up to PIPE_BUF bytes should be atomic
assert!(p.wait().is_ok(),
"wait() should either return Ok or panic");
panic!("short read on the CLOEXEC pipe")
}
}
}
}
// And at this point we've reached a special time in the life of the
// child. The child must now be considered hamstrung and unable to
// do anything other than syscalls really. Consider the following
// scenario:
//
// 1. Thread A of process 1 grabs the malloc() mutex
// 2. Thread B of process 1 forks(), creating thread C
// 3. Thread C of process 2 then attempts to malloc()
// 4. The memory of process 2 is the same as the memory of
// process 1, so the mutex is locked.
//
// This situation looks a lot like deadlock, right? It turns out
// that this is what pthread_atfork() takes care of, which is
// presumably implemented across platforms. The first thing that
// threads to *before* forking is to do things like grab the malloc
// mutex, and then after the fork they unlock it.
//
// Despite this information, libnative's spawn has been witnessed to
// deadlock on both OSX and FreeBSD. I'm not entirely sure why, but
// all collected backtraces point at malloc/free traffic in the
// child spawned process.
//
// For this reason, the block of code below should contain 0
// invocations of either malloc of free (or their related friends).
//
// As an example of not having malloc/free traffic, we don't close
// this file descriptor by dropping the FileDesc (which contains an
// allocation). Instead we just close it manually. This will never
// have the drop glue anyway because this code never returns (the
// child will either exec() or invoke libc::exit)
let _ = libc::close(input.raw());
fn fail(output: &mut AnonPipe) -> ! {
let errno = sys::os::errno() as u32;
let bytes = [
(errno >> 24) as u8,
(errno >> 16) as u8,
(errno >> 8) as u8,
(errno >> 0) as u8,
CLOEXEC_MSG_FOOTER[0], CLOEXEC_MSG_FOOTER[1],
CLOEXEC_MSG_FOOTER[2], CLOEXEC_MSG_FOOTER[3]
];
// pipe I/O up to PIPE_BUF bytes should be atomic
assert!(output.write(&bytes).is_ok());
unsafe { libc::_exit(1) }
}
rustrt::rust_unset_sigprocmask();
// If a stdio file descriptor is set to be ignored, we don't
// actually close it, but rather open up /dev/null into that
// file descriptor. Otherwise, the first file descriptor opened
// up in the child would be numbered as one of the stdio file
// descriptors, which is likely to wreak havoc.
let setup = |&: src: Option<AnonPipe>, dst: c_int| {
let src = match src {
None => {
let flags = if dst == libc::STDIN_FILENO {
libc::O_RDONLY
} else {
libc::O_RDWR
};
libc::open(devnull.as_ptr() as *const _, flags, 0)
}
Some(obj) => {
let fd = obj.raw();
// Leak the memory and the file descriptor. We're in the
// child now an all our resources are going to be
// cleaned up very soon
mem::forget(obj);
fd
}
};
src != -1 && retry(|| dup2(src, dst)) != -1
};
if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
// close all other fds
for fd in (3..getdtablesize()).rev() {
if fd != output.raw() {
let _ = close(fd as c_int);
}
}
match cfg.gid {
Some(u) => {
if libc::setgid(u as libc::gid_t) != 0 {
fail(&mut output);
}
}
None => {}
}
match cfg.uid {
Some(u) => {
// When dropping privileges from root, the `setgroups` call
// will remove any extraneous groups. If we don't call this,
// then even though our uid has dropped, we may still have
// groups that enable us to do super-user things. This will
// fail if we aren't root, so don't bother checking the
// return value, this is just done as an optimistic
// privilege dropping function.
extern {
fn setgroups(ngroups: libc::c_int,
ptr: *const libc::c_void) -> libc::c_int;
}
let _ = setgroups(0, ptr::null());
if libc::setuid(u as libc::uid_t) != 0 {
fail(&mut output);
}
}
None => {}
}
if cfg.detach {
// Don't check the error of setsid because it fails if we're the
// process leader already. We just forked so it shouldn't return
// error, but ignore it anyway.
let _ = libc::setsid();
}
if !dirp.is_null() && chdir(dirp) == -1 {
fail(&mut output);
}
if !envp.is_null() {
*sys::os::environ() = envp as *const _;
}
let _ = execvp(*argv, argv as *mut _);
fail(&mut output);
})
})
}
pub fn wait(&self) -> io::Result<ExitStatus> {
let mut status = 0 as c_int;
try!(cvt(retry(|| unsafe { c::waitpid(self.pid, &mut status, 0) })));
Ok(translate_status(status))
}
pub fn try_wait(&self) -> Option<ExitStatus> {
let mut status = 0 as c_int;
match retry(|| unsafe {
c::waitpid(self.pid, &mut status, c::WNOHANG)
}) {
n if n == self.pid => Some(translate_status(status)),
0 => None,
n => panic!("unknown waitpid error `{:?}`: {:?}", n,
super::last_error()),
}
}
}
fn with_argv<T,F>(prog: &CString, args: &[CString], cb: F) -> T
where F : FnOnce(*const *const libc::c_char) -> T
{
let mut ptrs: Vec<*const libc::c_char> = Vec::with_capacity(args.len()+1);
// Convert the CStrings into an array of pointers. Note: the
// lifetime of the various CStrings involved is guaranteed to be
// larger than the lifetime of our invocation of cb, but this is
// technically unsafe as the callback could leak these pointers
// out of our scope.
ptrs.push(prog.as_ptr());
ptrs.extend(args.iter().map(|tmp| tmp.as_ptr()));
// Add a terminating null pointer (required by libc).
ptrs.push(ptr::null());
cb(ptrs.as_ptr())
}
fn with_envp<T, F>(env: Option<&HashMap<OsString, OsString>>, cb: F) -> T
where F : FnOnce(*const c_void) -> T
{
// On posixy systems we can pass a char** for envp, which is a
// null-terminated array of "k=v\0" strings. Since we must create
// these strings locally, yet expose a raw pointer to them, we
// create a temporary vector to own the CStrings that outlives the
// call to cb.
match env {
Some(env) => {
let mut tmps = Vec::with_capacity(env.len());
for pair in env {
let mut kv = Vec::new();
kv.push_all(pair.0.as_bytes());
kv.push('=' as u8);
kv.push_all(pair.1.as_bytes());
kv.push(0); // terminating null
tmps.push(kv);
}
// As with `with_argv`, this is unsafe, since cb could leak the pointers.
let mut ptrs: Vec<*const libc::c_char> =
tmps.iter()
.map(|tmp| tmp.as_ptr() as *const libc::c_char)
.collect();
ptrs.push(ptr::null());
cb(ptrs.as_ptr() as *const c_void)
}
_ => cb(ptr::null())
}
}
fn translate_status(status: c_int) -> ExitStatus {
#![allow(non_snake_case)]
#[cfg(any(target_os = "linux", target_os = "android"))]
mod imp {
pub fn WIFEXITED(status: i32) -> bool { (status & 0xff) == 0 }
pub fn WEXITSTATUS(status: i32) -> i32 { (status >> 8) & 0xff }
pub fn WTERMSIG(status: i32) -> i32 { status & 0x7f }
}
#[cfg(any(target_os = "macos",
target_os = "ios",
target_os = "freebsd",
target_os = "dragonfly",
target_os = "openbsd"))]
mod imp {
pub fn WIFEXITED(status: i32) -> bool { (status & 0x7f) == 0 }
pub fn WEXITSTATUS(status: i32) -> i32 { status >> 8 }
pub fn WTERMSIG(status: i32) -> i32 { status & 0o177 }
}
if imp::WIFEXITED(status) {
ExitStatus::Code(imp::WEXITSTATUS(status))
} else {
ExitStatus::Signal(imp::WTERMSIG(status))
}
}