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Diffstat (limited to 'src/libstd/sys/unix/process.rs')
| -rw-r--r-- | src/libstd/sys/unix/process.rs | 627 |
1 files changed, 0 insertions, 627 deletions
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs deleted file mode 100644 index 8095325f83d..00000000000 --- a/src/libstd/sys/unix/process.rs +++ /dev/null @@ -1,627 +0,0 @@ -// 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. - -#![allow(deprecated)] // this module itself is essentially deprecated - -use prelude::v1::*; -use self::Req::*; - -use collections::HashMap; -use ffi::CString; -use hash::Hash; -use old_io::process::{ProcessExit, ExitStatus, ExitSignal}; -use old_io::{IoResult, EndOfFile}; -use libc::{self, pid_t, c_void, c_int}; -use io; -use mem; -use sys::os; -use old_path::BytesContainer; -use ptr; -use sync::mpsc::{channel, Sender, Receiver}; -use sys::fs::FileDesc; -use sys::{self, retry, c, wouldblock, set_nonblocking, ms_to_timeval}; -use sys_common::helper_thread::Helper; -use sys_common::{AsInner, mkerr_libc, timeout}; - -pub use sys_common::ProcessConfig; - -helper_init! { static HELPER: Helper<Req> } - -/// The unique id of the process (this should never be negative). -pub struct Process { - pub pid: pid_t -} - -enum Req { - NewChild(libc::pid_t, Sender<ProcessExit>, u64), -} - -const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX"; - -impl Process { - pub fn id(&self) -> pid_t { - self.pid - } - - pub unsafe fn kill(&self, signal: isize) -> IoResult<()> { - Process::killpid(self.pid, signal) - } - - pub unsafe fn killpid(pid: pid_t, signal: isize) -> IoResult<()> { - let r = libc::funcs::posix88::signal::kill(pid, signal as c_int); - mkerr_libc(r) - } - - pub fn spawn<K, V, C, P>(cfg: &C, in_fd: Option<P>, - out_fd: Option<P>, err_fd: Option<P>) - -> IoResult<Process> - where C: ProcessConfig<K, V>, P: AsInner<FileDesc>, - K: BytesContainer + Eq + Hash, V: BytesContainer - { - use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp}; - - 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); - } - - #[cfg(all(target_os = "android", target_arch = "aarch64"))] - unsafe fn getdtablesize() -> c_int { - libc::sysconf(libc::consts::os::sysconf::_SC_OPEN_MAX) as c_int - } - #[cfg(not(all(target_os = "android", target_arch = "aarch64")))] - unsafe fn getdtablesize() -> c_int { - libc::funcs::bsd44::getdtablesize() - } - - let dirp = cfg.cwd().map(|c| c.as_ptr()).unwrap_or(ptr::null()); - - // temporary until unboxed closures land - let cfg = unsafe { - mem::transmute::<&ProcessConfig<K,V>,&'static ProcessConfig<K,V>>(cfg) - }; - - with_envp(cfg.env(), move|envp: *const c_void| { - with_argv(cfg.program(), cfg.args(), move|argv: *const *const libc::c_char| unsafe { - let (input, mut output) = try!(sys::os::pipe()); - - // We may use this in the child, so perform allocations before the - // fork - let devnull = b"/dev/null\0"; - - set_cloexec(output.fd()); - - let pid = fork(); - if pid < 0 { - return Err(super::last_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]; - return 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(0).is_ok(), "wait(0) should either return Ok or panic"); - Err(super::decode_error(errno)) - } - Err(ref e) if e.kind == EndOfFile => Ok(p), - Err(e) => { - assert!(p.wait(0).is_ok(), "wait(0) 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(0).is_ok(), "wait(0) 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.fd()); - - fn fail(output: &mut FileDesc) -> ! { - 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 (via a -1 file - // descriptor), then 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<P>, 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.as_inner().fd(); - // 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.fd() { - 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, deadline: u64) -> IoResult<ProcessExit> { - use cmp; - use sync::mpsc::TryRecvError; - - static mut WRITE_FD: libc::c_int = 0; - - let mut status = 0 as c_int; - if deadline == 0 { - return match retry(|| unsafe { c::waitpid(self.pid, &mut status, 0) }) { - -1 => panic!("unknown waitpid error: {:?}", super::last_error()), - _ => Ok(translate_status(status)), - } - } - - // On unix, wait() and its friends have no timeout parameters, so there is - // no way to time out a thread in wait(). From some googling and some - // thinking, it appears that there are a few ways to handle timeouts in - // wait(), but the only real reasonable one for a multi-threaded program is - // to listen for SIGCHLD. - // - // With this in mind, the waiting mechanism with a timeout barely uses - // waitpid() at all. There are a few times that waitpid() is invoked with - // WNOHANG, but otherwise all the necessary blocking is done by waiting for - // a SIGCHLD to arrive (and that blocking has a timeout). Note, however, - // that waitpid() is still used to actually reap the child. - // - // Signal handling is super tricky in general, and this is no exception. Due - // to the async nature of SIGCHLD, we use the self-pipe trick to transmit - // data out of the signal handler to the rest of the application. The first - // idea would be to have each thread waiting with a timeout to read this - // output file descriptor, but a write() is akin to a signal(), not a - // broadcast(), so it would only wake up one thread, and possibly the wrong - // thread. Hence a helper thread is used. - // - // The helper thread here is responsible for farming requests for a - // waitpid() with a timeout, and then processing all of the wait requests. - // By guaranteeing that only this helper thread is reading half of the - // self-pipe, we're sure that we'll never lose a SIGCHLD. This helper thread - // is also responsible for select() to wait for incoming messages or - // incoming SIGCHLD messages, along with passing an appropriate timeout to - // select() to wake things up as necessary. - // - // The ordering of the following statements is also very purposeful. First, - // we must be guaranteed that the helper thread is booted and available to - // receive SIGCHLD signals, and then we must also ensure that we do a - // nonblocking waitpid() at least once before we go ask the sigchld helper. - // This prevents the race where the child exits, we boot the helper, and - // then we ask for the child's exit status (never seeing a sigchld). - // - // The actual communication between the helper thread and this thread is - // quite simple, just a channel moving data around. - - HELPER.boot(register_sigchld, waitpid_helper); - - match self.try_wait() { - Some(ret) => return Ok(ret), - None => {} - } - - let (tx, rx) = channel(); - HELPER.send(NewChild(self.pid, tx, deadline)); - return match rx.recv() { - Ok(e) => Ok(e), - Err(..) => Err(timeout("wait timed out")), - }; - - // Register a new SIGCHLD handler, returning the reading half of the - // self-pipe plus the old handler registered (return value of sigaction). - // - // Be sure to set up the self-pipe first because as soon as we register a - // handler we're going to start receiving signals. - fn register_sigchld() -> (libc::c_int, c::sigaction) { - unsafe { - let mut pipes = [0; 2]; - assert_eq!(libc::pipe(pipes.as_mut_ptr()), 0); - set_nonblocking(pipes[0], true); - set_nonblocking(pipes[1], true); - WRITE_FD = pipes[1]; - - let mut old: c::sigaction = mem::zeroed(); - let mut new: c::sigaction = mem::zeroed(); - new.sa_handler = sigchld_handler; - new.sa_flags = c::SA_NOCLDSTOP; - assert_eq!(c::sigaction(c::SIGCHLD, &new, &mut old), 0); - (pipes[0], old) - } - } - - // Helper thread for processing SIGCHLD messages - fn waitpid_helper(input: libc::c_int, - messages: Receiver<Req>, - (read_fd, old): (libc::c_int, c::sigaction)) { - set_nonblocking(input, true); - let mut set: c::fd_set = unsafe { mem::zeroed() }; - let mut tv: libc::timeval; - let mut active = Vec::<(libc::pid_t, Sender<ProcessExit>, u64)>::new(); - let max = cmp::max(input, read_fd) + 1; - - 'outer: loop { - // Figure out the timeout of our syscall-to-happen. If we're waiting - // for some processes, then they'll have a timeout, otherwise we - // wait indefinitely for a message to arrive. - // - // FIXME: sure would be nice to not have to scan the entire array - let min = active.iter().map(|a| a.2).enumerate().min_by(|p| { - p.1 - }); - let (p, idx) = match min { - Some((idx, deadline)) => { - let now = sys::timer::now(); - let ms = if now < deadline {deadline - now} else {0}; - tv = ms_to_timeval(ms); - (&mut tv as *mut _, idx) - } - None => (ptr::null_mut(), -1), - }; - - // Wait for something to happen - c::fd_set(&mut set, input); - c::fd_set(&mut set, read_fd); - match unsafe { c::select(max, &mut set, ptr::null_mut(), - ptr::null_mut(), p) } { - // interrupted, retry - -1 if os::errno() == libc::EINTR as i32 => continue, - - // We read something, break out and process - 1 | 2 => {} - - // Timeout, the pending request is removed - 0 => { - drop(active.remove(idx)); - continue - } - - n => panic!("error in select {:?} ({:?})", os::errno(), n), - } - - // Process any pending messages - if drain(input) { - loop { - match messages.try_recv() { - Ok(NewChild(pid, tx, deadline)) => { - active.push((pid, tx, deadline)); - } - // Once we've been disconnected it means the main - // thread is exiting (at_exit has run). We could - // still have active waiter for other threads, so - // we're just going to drop them all on the floor. - // This means that they won't receive a "you're - // done" message in which case they'll be considered - // as timed out, but more generally errors will - // start propagating. - Err(TryRecvError::Disconnected) => { - break 'outer; - } - Err(TryRecvError::Empty) => break, - } - } - } - - // If a child exited (somehow received SIGCHLD), then poll all - // children to see if any of them exited. - // - // We also attempt to be responsible netizens when dealing with - // SIGCHLD by invoking any previous SIGCHLD handler instead of just - // ignoring any previous SIGCHLD handler. Note that we don't provide - // a 1:1 mapping of our handler invocations to the previous handler - // invocations because we drain the `read_fd` entirely. This is - // probably OK because the kernel is already allowed to coalesce - // simultaneous signals, we're just doing some extra coalescing. - // - // Another point of note is that this likely runs the signal handler - // on a different thread than the one that received the signal. I - // *think* this is ok at this time. - // - // The main reason for doing this is to allow stdtest to run native - // tests as well. Both libgreen and libnative are running around - // with process timeouts, but libgreen should get there first - // (currently libuv doesn't handle old signal handlers). - if drain(read_fd) { - let i: usize = unsafe { mem::transmute(old.sa_handler) }; - if i != 0 { - assert!(old.sa_flags & c::SA_SIGINFO == 0); - (old.sa_handler)(c::SIGCHLD); - } - - // FIXME: sure would be nice to not have to scan the entire - // array... - active.retain(|&(pid, ref tx, _)| { - let pr = Process { pid: pid }; - match pr.try_wait() { - Some(msg) => { tx.send(msg).unwrap(); false } - None => true, - } - }); - } - } - - // Once this helper thread is done, we re-register the old sigchld - // handler and close our intermediate file descriptors. - unsafe { - assert_eq!(c::sigaction(c::SIGCHLD, &old, ptr::null_mut()), 0); - let _ = libc::close(read_fd); - let _ = libc::close(WRITE_FD); - WRITE_FD = -1; - } - } - - // Drain all pending data from the file descriptor, returning if any data - // could be drained. This requires that the file descriptor is in - // nonblocking mode. - fn drain(fd: libc::c_int) -> bool { - let mut ret = false; - loop { - let mut buf = [0u8; 1]; - match unsafe { - libc::read(fd, buf.as_mut_ptr() as *mut libc::c_void, - buf.len() as libc::size_t) - } { - n if n > 0 => { ret = true; } - 0 => return true, - -1 if wouldblock() => return ret, - n => panic!("bad read {} ({})", - io::Error::last_os_error(), n), - } - } - } - - // Signal handler for SIGCHLD signals, must be async-signal-safe! - // - // This function will write to the writing half of the "self pipe" to wake - // up the helper thread if it's waiting. Note that this write must be - // nonblocking because if it blocks and the reader is the thread we - // interrupted, then we'll deadlock. - // - // When writing, if the write returns EWOULDBLOCK then we choose to ignore - // it. At that point we're guaranteed that there's something in the pipe - // which will wake up the other end at some point, so we just allow this - // signal to be coalesced with the pending signals on the pipe. - extern fn sigchld_handler(_signum: libc::c_int) { - let msg = 1; - match unsafe { - libc::write(WRITE_FD, &msg as *const _ as *const libc::c_void, 1) - } { - 1 => {} - -1 if wouldblock() => {} // see above comments - n => panic!("bad error on write fd: {:?} {:?}", n, os::errno()), - } - } - } - - pub fn try_wait(&self) -> Option<ProcessExit> { - 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<K,V,T,F>(env: Option<&HashMap<K, V>>, - cb: F) - -> T - where F : FnOnce(*const c_void) -> T, - K : BytesContainer + Eq + Hash, - V : BytesContainer -{ - // 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.container_as_bytes()); - kv.push('=' as u8); - kv.push_all(pair.1.container_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) -> ProcessExit { - #![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 = "bitrig", - 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(imp::WEXITSTATUS(status) as isize) - } else { - ExitSignal(imp::WTERMSIG(status) as isize) - } -} |