1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use libc::{pid_t, c_void, c_int};
13 use std::c_str::CString;
18 use std::rt::rtio::{ProcessConfig, IoResult, IoError};
24 #[cfg(windows)] use std::string::String;
25 #[cfg(unix)] use super::c;
26 #[cfg(unix)] use super::retry;
27 #[cfg(unix)] use io::helper_thread::Helper;
30 helper_init!(static mut HELPER: Helper<Req>)
33 * A value representing a child process.
35 * The lifetime of this value is linked to the lifetime of the actual
36 * process - the Process destructor calls self.finish() which waits
37 * for the process to terminate.
40 /// The unique id of the process (this should never be negative).
43 /// A handle to the process - on unix this will always be NULL, but on
44 /// windows it will be a HANDLE to the process, which will prevent the
45 /// pid being re-used until the handle is closed.
48 /// None until finish() is called.
49 exit_code: Option<rtio::ProcessExit>,
51 /// Manually delivered signal
52 exit_signal: Option<int>,
54 /// Deadline after which wait() will return
60 NewChild(libc::pid_t, Sender<rtio::ProcessExit>, u64),
64 /// Creates a new process using native process-spawning abilities provided
65 /// by the OS. Operations on this process will be blocking instead of using
66 /// the runtime for sleeping just this current task.
67 pub fn spawn(cfg: ProcessConfig)
68 -> IoResult<(Process, Vec<Option<file::FileDesc>>)>
70 // right now we only handle stdin/stdout/stderr.
71 if cfg.extra_io.len() > 0 {
72 return Err(super::unimpl());
75 fn get_io(io: rtio::StdioContainer,
76 ret: &mut Vec<Option<file::FileDesc>>)
77 -> IoResult<Option<file::FileDesc>>
80 rtio::Ignored => { ret.push(None); Ok(None) }
81 rtio::InheritFd(fd) => {
83 Ok(Some(file::FileDesc::new(fd, true)))
85 rtio::CreatePipe(readable, _writable) => {
86 let (reader, writer) = try!(pipe());
87 let (theirs, ours) = if readable {
98 let mut ret_io = Vec::new();
99 let res = spawn_process_os(cfg,
100 try!(get_io(cfg.stdin, &mut ret_io)),
101 try!(get_io(cfg.stdout, &mut ret_io)),
102 try!(get_io(cfg.stderr, &mut ret_io)));
119 pub fn kill(pid: libc::pid_t, signum: int) -> IoResult<()> {
120 unsafe { killpid(pid, signum) }
124 impl rtio::RtioProcess for Process {
125 fn id(&self) -> pid_t { self.pid }
127 fn set_timeout(&mut self, timeout: Option<u64>) {
128 self.deadline = timeout.map(|i| i + ::io::timer::now()).unwrap_or(0);
131 fn wait(&mut self) -> IoResult<rtio::ProcessExit> {
132 match self.exit_code {
133 Some(code) => Ok(code),
135 let code = try!(waitpid(self.pid, self.deadline));
136 // On windows, waitpid will never return a signal. If a signal
137 // was successfully delivered to the process, however, we can
138 // consider it as having died via a signal.
139 let code = match self.exit_signal {
141 Some(signal) if cfg!(windows) => rtio::ExitSignal(signal),
144 self.exit_code = Some(code);
150 fn kill(&mut self, signum: int) -> IoResult<()> {
151 #[cfg(unix)] use ERROR = libc::EINVAL;
152 #[cfg(windows)] use ERROR = libc::ERROR_NOTHING_TO_TERMINATE;
154 // On linux (and possibly other unices), a process that has exited will
155 // continue to accept signals because it is "defunct". The delivery of
156 // signals will only fail once the child has been reaped. For this
157 // reason, if the process hasn't exited yet, then we attempt to collect
158 // their status with WNOHANG.
159 if self.exit_code.is_none() {
160 match waitpid_nowait(self.pid) {
161 Some(code) => { self.exit_code = Some(code); }
166 // if the process has finished, and therefore had waitpid called,
167 // and we kill it, then on unix we might ending up killing a
168 // newer process that happens to have the same (re-used) id
169 match self.exit_code {
170 Some(..) => return Err(IoError {
173 detail: Some("can't kill an exited process".to_str()),
178 // A successfully delivered signal that isn't 0 (just a poll for being
179 // alive) is recorded for windows (see wait())
180 match unsafe { killpid(self.pid, signum) } {
181 Ok(()) if signum == 0 => Ok(()),
182 Ok(()) => { self.exit_signal = Some(signum); Ok(()) }
188 impl Drop for Process {
190 free_handle(self.handle);
194 fn pipe() -> IoResult<(file::FileDesc, file::FileDesc)> {
195 #[cfg(unix)] use ERROR = libc::EMFILE;
196 #[cfg(windows)] use ERROR = libc::WSAEMFILE;
197 struct Closer { fd: libc::c_int }
199 let os::Pipe { reader, writer } = match unsafe { os::pipe() } {
201 Err(io::IoError { detail, .. }) => return Err(IoError {
207 let mut reader = Closer { fd: reader };
208 let mut writer = Closer { fd: writer };
210 let native_reader = file::FileDesc::new(reader.fd, true);
212 let native_writer = file::FileDesc::new(writer.fd, true);
214 return Ok((native_reader, native_writer));
216 impl Drop for Closer {
219 let _ = unsafe { libc::close(self.fd) };
226 unsafe fn killpid(pid: pid_t, signal: int) -> IoResult<()> {
227 let handle = libc::OpenProcess(libc::PROCESS_TERMINATE |
228 libc::PROCESS_QUERY_INFORMATION,
229 libc::FALSE, pid as libc::DWORD);
230 if handle.is_null() {
231 return Err(super::last_error())
233 let ret = match signal {
234 // test for existence on signal 0
237 let ret = libc::GetExitCodeProcess(handle, &mut status);
239 Err(super::last_error())
240 } else if status != libc::STILL_ACTIVE {
242 code: libc::ERROR_NOTHING_TO_TERMINATE as uint,
250 15 | 9 => { // sigterm or sigkill
251 let ret = libc::TerminateProcess(handle, 1);
252 super::mkerr_winbool(ret)
255 code: libc::ERROR_CALL_NOT_IMPLEMENTED as uint,
257 detail: Some("unsupported signal on windows".to_string()),
260 let _ = libc::CloseHandle(handle);
265 unsafe fn killpid(pid: pid_t, signal: int) -> IoResult<()> {
266 let r = libc::funcs::posix88::signal::kill(pid, signal as c_int);
270 struct SpawnProcessResult {
276 fn spawn_process_os(cfg: ProcessConfig,
277 in_fd: Option<file::FileDesc>,
278 out_fd: Option<file::FileDesc>,
279 err_fd: Option<file::FileDesc>)
280 -> IoResult<SpawnProcessResult> {
281 use libc::types::os::arch::extra::{DWORD, HANDLE, STARTUPINFO};
282 use libc::consts::os::extra::{
284 STARTF_USESTDHANDLES,
285 INVALID_HANDLE_VALUE,
286 DUPLICATE_SAME_ACCESS
288 use libc::funcs::extra::kernel32::{
294 use libc::funcs::extra::msvcrt::get_osfhandle;
298 if cfg.gid.is_some() || cfg.uid.is_some() {
300 code: libc::ERROR_CALL_NOT_IMPLEMENTED as uint,
302 detail: Some("unsupported gid/uid requested on windows".to_str()),
307 let mut si = zeroed_startupinfo();
308 si.cb = mem::size_of::<STARTUPINFO>() as DWORD;
309 si.dwFlags = STARTF_USESTDHANDLES;
311 let cur_proc = GetCurrentProcess();
313 // Similarly to unix, we don't actually leave holes for the stdio file
314 // descriptors, but rather open up /dev/null equivalents. These
315 // equivalents are drawn from libuv's windows process spawning.
316 let set_fd = |fd: &Option<file::FileDesc>, slot: &mut HANDLE,
320 let access = if is_stdin {
321 libc::FILE_GENERIC_READ
323 libc::FILE_GENERIC_WRITE | libc::FILE_READ_ATTRIBUTES
325 let size = mem::size_of::<libc::SECURITY_ATTRIBUTES>();
326 let mut sa = libc::SECURITY_ATTRIBUTES {
327 nLength: size as libc::DWORD,
328 lpSecurityDescriptor: ptr::mut_null(),
331 let filename = "NUL".to_utf16().append_one(0);
332 *slot = libc::CreateFileW(filename.as_ptr(),
334 libc::FILE_SHARE_READ |
335 libc::FILE_SHARE_WRITE,
340 if *slot == INVALID_HANDLE_VALUE as libc::HANDLE {
341 return Err(super::last_error())
345 let orig = get_osfhandle(fd.fd()) as HANDLE;
346 if orig == INVALID_HANDLE_VALUE as HANDLE {
347 return Err(super::last_error())
349 if DuplicateHandle(cur_proc, orig, cur_proc, slot,
350 0, TRUE, DUPLICATE_SAME_ACCESS) == FALSE {
351 return Err(super::last_error())
358 try!(set_fd(&in_fd, &mut si.hStdInput, true));
359 try!(set_fd(&out_fd, &mut si.hStdOutput, false));
360 try!(set_fd(&err_fd, &mut si.hStdError, false));
362 let cmd_str = make_command_line(cfg.program, cfg.args);
363 let mut pi = zeroed_process_information();
364 let mut create_err = None;
366 // stolen from the libuv code.
367 let mut flags = libc::CREATE_UNICODE_ENVIRONMENT;
369 flags |= libc::DETACHED_PROCESS | libc::CREATE_NEW_PROCESS_GROUP;
372 with_envp(cfg.env, |envp| {
373 with_dirp(cfg.cwd, |dirp| {
374 let mut cmd_str = cmd_str.to_utf16().append_one(0);
375 let created = CreateProcessW(ptr::null(),
376 cmd_str.as_mut_ptr(),
382 if created == FALSE {
383 create_err = Some(super::last_error());
388 assert!(CloseHandle(si.hStdInput) != 0);
389 assert!(CloseHandle(si.hStdOutput) != 0);
390 assert!(CloseHandle(si.hStdError) != 0);
393 Some(err) => return Err(err),
397 // We close the thread handle because we don't care about keeping the
398 // thread id valid, and we aren't keeping the thread handle around to be
399 // able to close it later. We don't close the process handle however
400 // because std::we want the process id to stay valid at least until the
401 // calling code closes the process handle.
402 assert!(CloseHandle(pi.hThread) != 0);
404 Ok(SpawnProcessResult {
405 pid: pi.dwProcessId as pid_t,
406 handle: pi.hProcess as *mut ()
412 fn zeroed_startupinfo() -> libc::types::os::arch::extra::STARTUPINFO {
413 libc::types::os::arch::extra::STARTUPINFO {
415 lpReserved: ptr::mut_null(),
416 lpDesktop: ptr::mut_null(),
417 lpTitle: ptr::mut_null(),
428 lpReserved2: ptr::mut_null(),
429 hStdInput: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
430 hStdOutput: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
431 hStdError: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
436 fn zeroed_process_information() -> libc::types::os::arch::extra::PROCESS_INFORMATION {
437 libc::types::os::arch::extra::PROCESS_INFORMATION {
438 hProcess: ptr::mut_null(),
439 hThread: ptr::mut_null(),
446 fn make_command_line(prog: &CString, args: &[CString]) -> String {
447 let mut cmd = String::new();
448 append_arg(&mut cmd, prog.as_str()
449 .expect("expected program name to be utf-8 encoded"));
450 for arg in args.iter() {
452 append_arg(&mut cmd, arg.as_str()
453 .expect("expected argument to be utf-8 encoded"));
457 fn append_arg(cmd: &mut String, arg: &str) {
458 let quote = arg.chars().any(|c| c == ' ' || c == '\t');
462 let argvec: Vec<char> = arg.chars().collect();
463 for i in range(0u, argvec.len()) {
464 append_char_at(cmd, &argvec, i);
471 fn append_char_at(cmd: &mut String, arg: &Vec<char>, i: uint) {
475 cmd.push_str("\\\"");
478 if backslash_run_ends_in_quote(arg, i) {
479 // Double all backslashes that are in runs before quotes.
480 cmd.push_str("\\\\");
482 // Pass other backslashes through unescaped.
492 fn backslash_run_ends_in_quote(s: &Vec<char>, mut i: uint) -> bool {
493 while i < s.len() && *s.get(i) == '\\' {
496 return i < s.len() && *s.get(i) == '"';
501 fn spawn_process_os(cfg: ProcessConfig,
502 in_fd: Option<file::FileDesc>,
503 out_fd: Option<file::FileDesc>,
504 err_fd: Option<file::FileDesc>)
505 -> IoResult<SpawnProcessResult>
507 use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp};
508 use libc::funcs::bsd44::getdtablesize;
513 pub fn rust_unset_sigprocmask();
517 #[cfg(target_os = "macos")]
518 unsafe fn set_environ(envp: *const c_void) {
519 extern { fn _NSGetEnviron() -> *mut *const c_void; }
521 *_NSGetEnviron() = envp;
523 #[cfg(not(target_os = "macos"))]
524 unsafe fn set_environ(envp: *const c_void) {
525 extern { static mut environ: *const c_void; }
529 unsafe fn set_cloexec(fd: c_int) {
530 let ret = c::ioctl(fd, c::FIOCLEX);
534 let dirp = cfg.cwd.map(|c| c.with_ref(|p| p)).unwrap_or(ptr::null());
536 with_envp(cfg.env, proc(envp) {
537 with_argv(cfg.program, cfg.args, proc(argv) unsafe {
538 let (mut input, mut output) = try!(pipe());
540 // We may use this in the child, so perform allocations before the
542 let devnull = "/dev/null".to_c_str();
544 set_cloexec(output.fd());
548 return Err(super::last_error())
551 let mut bytes = [0, ..4];
552 return match input.inner_read(bytes) {
554 let errno = (bytes[0] << 24) as i32 |
555 (bytes[1] << 16) as i32 |
556 (bytes[2] << 8) as i32 |
557 (bytes[3] << 0) as i32;
565 Ok(SpawnProcessResult {
567 handle: ptr::mut_null()
570 Ok(..) => fail!("short read on the cloexec pipe"),
573 // And at this point we've reached a special time in the life of the
574 // child. The child must now be considered hamstrung and unable to
575 // do anything other than syscalls really. Consider the following
578 // 1. Thread A of process 1 grabs the malloc() mutex
579 // 2. Thread B of process 1 forks(), creating thread C
580 // 3. Thread C of process 2 then attempts to malloc()
581 // 4. The memory of process 2 is the same as the memory of
582 // process 1, so the mutex is locked.
584 // This situation looks a lot like deadlock, right? It turns out
585 // that this is what pthread_atfork() takes care of, which is
586 // presumably implemented across platforms. The first thing that
587 // threads to *before* forking is to do things like grab the malloc
588 // mutex, and then after the fork they unlock it.
590 // Despite this information, libnative's spawn has been witnessed to
591 // deadlock on both OSX and FreeBSD. I'm not entirely sure why, but
592 // all collected backtraces point at malloc/free traffic in the
593 // child spawned process.
595 // For this reason, the block of code below should contain 0
596 // invocations of either malloc of free (or their related friends).
598 // As an example of not having malloc/free traffic, we don't close
599 // this file descriptor by dropping the FileDesc (which contains an
600 // allocation). Instead we just close it manually. This will never
601 // have the drop glue anyway because this code never returns (the
602 // child will either exec() or invoke libc::exit)
603 let _ = libc::close(input.fd());
605 fn fail(output: &mut file::FileDesc) -> ! {
606 let errno = os::errno();
613 assert!(output.inner_write(bytes).is_ok());
614 unsafe { libc::_exit(1) }
617 rustrt::rust_unset_sigprocmask();
619 // If a stdio file descriptor is set to be ignored (via a -1 file
620 // descriptor), then we don't actually close it, but rather open
621 // up /dev/null into that file descriptor. Otherwise, the first file
622 // descriptor opened up in the child would be numbered as one of the
623 // stdio file descriptors, which is likely to wreak havoc.
624 let setup = |src: Option<file::FileDesc>, dst: c_int| {
625 let src = match src {
627 let flags = if dst == libc::STDIN_FILENO {
632 devnull.with_ref(|p| libc::open(p, flags, 0))
636 // Leak the memory and the file descriptor. We're in the
637 // child now an all our resources are going to be
638 // cleaned up very soon
643 src != -1 && retry(|| dup2(src, dst)) != -1
646 if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
647 if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
648 if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
650 // close all other fds
651 for fd in range(3, getdtablesize()).rev() {
652 if fd != output.fd() {
653 let _ = close(fd as c_int);
659 if libc::setgid(u as libc::gid_t) != 0 {
667 // When dropping privileges from root, the `setgroups` call
668 // will remove any extraneous groups. If we don't call this,
669 // then even though our uid has dropped, we may still have
670 // groups that enable us to do super-user things. This will
671 // fail if we aren't root, so don't bother checking the
672 // return value, this is just done as an optimistic
673 // privilege dropping function.
675 fn setgroups(ngroups: libc::c_int,
676 ptr: *const libc::c_void) -> libc::c_int;
678 let _ = setgroups(0, 0 as *const libc::c_void);
680 if libc::setuid(u as libc::uid_t) != 0 {
687 // Don't check the error of setsid because it fails if we're the
688 // process leader already. We just forked so it shouldn't return
689 // error, but ignore it anyway.
690 let _ = libc::setsid();
692 if !dirp.is_null() && chdir(dirp) == -1 {
698 let _ = execvp(*argv, argv as *mut _);
705 fn with_argv<T>(prog: &CString, args: &[CString],
706 cb: proc(*const *const libc::c_char) -> T) -> T {
707 let mut ptrs: Vec<*const libc::c_char> = Vec::with_capacity(args.len()+1);
709 // Convert the CStrings into an array of pointers. Note: the
710 // lifetime of the various CStrings involved is guaranteed to be
711 // larger than the lifetime of our invocation of cb, but this is
712 // technically unsafe as the callback could leak these pointers
714 ptrs.push(prog.with_ref(|buf| buf));
715 ptrs.extend(args.iter().map(|tmp| tmp.with_ref(|buf| buf)));
717 // Add a terminating null pointer (required by libc).
718 ptrs.push(ptr::null());
724 fn with_envp<T>(env: Option<&[(CString, CString)]>,
725 cb: proc(*const c_void) -> T) -> T {
726 // On posixy systems we can pass a char** for envp, which is a
727 // null-terminated array of "k=v\0" strings. Since we must create
728 // these strings locally, yet expose a raw pointer to them, we
729 // create a temporary vector to own the CStrings that outlives the
733 let mut tmps = Vec::with_capacity(env.len());
735 for pair in env.iter() {
736 let mut kv = Vec::new();
737 kv.push_all(pair.ref0().as_bytes_no_nul());
739 kv.push_all(pair.ref1().as_bytes()); // includes terminal \0
743 // As with `with_argv`, this is unsafe, since cb could leak the pointers.
744 let mut ptrs: Vec<*const libc::c_char> =
746 .map(|tmp| tmp.as_ptr() as *const libc::c_char)
748 ptrs.push(ptr::null());
750 cb(ptrs.as_ptr() as *const c_void)
757 fn with_envp<T>(env: Option<&[(CString, CString)]>, cb: |*mut c_void| -> T) -> T {
758 // On win32 we pass an "environment block" which is not a char**, but
759 // rather a concatenation of null-terminated k=v\0 sequences, with a final
763 let mut blk = Vec::new();
765 for pair in env.iter() {
766 let kv = format!("{}={}",
767 pair.ref0().as_str().unwrap(),
768 pair.ref1().as_str().unwrap());
769 blk.push_all(kv.to_utf16().as_slice());
775 cb(blk.as_mut_ptr() as *mut c_void)
777 _ => cb(ptr::mut_null())
782 fn with_dirp<T>(d: Option<&CString>, cb: |*const u16| -> T) -> T {
785 let dir_str = dir.as_str()
786 .expect("expected workingdirectory to be utf-8 encoded");
787 let dir_str = dir_str.to_utf16().append_one(0);
790 None => cb(ptr::null())
795 fn free_handle(handle: *mut ()) {
797 libc::CloseHandle(mem::transmute(handle)) != 0
802 fn free_handle(_handle: *mut ()) {
803 // unix has no process handle object, just a pid
807 fn translate_status(status: c_int) -> rtio::ProcessExit {
808 #![allow(non_snake_case_functions)]
809 #[cfg(target_os = "linux")]
810 #[cfg(target_os = "android")]
812 pub fn WIFEXITED(status: i32) -> bool { (status & 0xff) == 0 }
813 pub fn WEXITSTATUS(status: i32) -> i32 { (status >> 8) & 0xff }
814 pub fn WTERMSIG(status: i32) -> i32 { status & 0x7f }
817 #[cfg(target_os = "macos")]
818 #[cfg(target_os = "ios")]
819 #[cfg(target_os = "freebsd")]
821 pub fn WIFEXITED(status: i32) -> bool { (status & 0x7f) == 0 }
822 pub fn WEXITSTATUS(status: i32) -> i32 { status >> 8 }
823 pub fn WTERMSIG(status: i32) -> i32 { status & 0o177 }
826 if imp::WIFEXITED(status) {
827 rtio::ExitStatus(imp::WEXITSTATUS(status) as int)
829 rtio::ExitSignal(imp::WTERMSIG(status) as int)
834 * Waits for a process to exit and returns the exit code, failing
835 * if there is no process with the specified id.
837 * Note that this is private to avoid race conditions on unix where if
838 * a user calls waitpid(some_process.get_id()) then some_process.finish()
839 * and some_process.destroy() and some_process.finalize() will then either
840 * operate on a none-existent process or, even worse, on a newer process
844 fn waitpid(pid: pid_t, deadline: u64) -> IoResult<rtio::ProcessExit> {
845 use libc::types::os::arch::extra::DWORD;
846 use libc::consts::os::extra::{
848 PROCESS_QUERY_INFORMATION,
855 use libc::funcs::extra::kernel32::{
863 let process = OpenProcess(SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
866 if process.is_null() {
867 return Err(super::last_error())
872 if GetExitCodeProcess(process, &mut status) == FALSE {
873 let err = Err(super::last_error());
874 assert!(CloseHandle(process) != 0);
877 if status != STILL_ACTIVE {
878 assert!(CloseHandle(process) != 0);
879 return Ok(rtio::ExitStatus(status as int));
881 let interval = if deadline == 0 {
884 let now = ::io::timer::now();
885 if deadline < now {0} else {(deadline - now) as u32}
887 match WaitForSingleObject(process, interval) {
890 assert!(CloseHandle(process) != 0);
891 return Err(util::timeout("process wait timed out"))
894 let err = Err(super::last_error());
895 assert!(CloseHandle(process) != 0);
904 fn waitpid(pid: pid_t, deadline: u64) -> IoResult<rtio::ProcessExit> {
908 static mut WRITE_FD: libc::c_int = 0;
910 let mut status = 0 as c_int;
912 return match retry(|| unsafe { c::waitpid(pid, &mut status, 0) }) {
913 -1 => fail!("unknown waitpid error: {}", super::last_error().code),
914 _ => Ok(translate_status(status)),
918 // On unix, wait() and its friends have no timeout parameters, so there is
919 // no way to time out a thread in wait(). From some googling and some
920 // thinking, it appears that there are a few ways to handle timeouts in
921 // wait(), but the only real reasonable one for a multi-threaded program is
922 // to listen for SIGCHLD.
924 // With this in mind, the waiting mechanism with a timeout barely uses
925 // waitpid() at all. There are a few times that waitpid() is invoked with
926 // WNOHANG, but otherwise all the necessary blocking is done by waiting for
927 // a SIGCHLD to arrive (and that blocking has a timeout). Note, however,
928 // that waitpid() is still used to actually reap the child.
930 // Signal handling is super tricky in general, and this is no exception. Due
931 // to the async nature of SIGCHLD, we use the self-pipe trick to transmit
932 // data out of the signal handler to the rest of the application. The first
933 // idea would be to have each thread waiting with a timeout to read this
934 // output file descriptor, but a write() is akin to a signal(), not a
935 // broadcast(), so it would only wake up one thread, and possibly the wrong
936 // thread. Hence a helper thread is used.
938 // The helper thread here is responsible for farming requests for a
939 // waitpid() with a timeout, and then processing all of the wait requests.
940 // By guaranteeing that only this helper thread is reading half of the
941 // self-pipe, we're sure that we'll never lose a SIGCHLD. This helper thread
942 // is also responsible for select() to wait for incoming messages or
943 // incoming SIGCHLD messages, along with passing an appropriate timeout to
944 // select() to wake things up as necessary.
946 // The ordering of the following statements is also very purposeful. First,
947 // we must be guaranteed that the helper thread is booted and available to
948 // receive SIGCHLD signals, and then we must also ensure that we do a
949 // nonblocking waitpid() at least once before we go ask the sigchld helper.
950 // This prevents the race where the child exits, we boot the helper, and
951 // then we ask for the child's exit status (never seeing a sigchld).
953 // The actual communication between the helper thread and this thread is
954 // quite simple, just a channel moving data around.
956 unsafe { HELPER.boot(register_sigchld, waitpid_helper) }
958 match waitpid_nowait(pid) {
959 Some(ret) => return Ok(ret),
963 let (tx, rx) = channel();
964 unsafe { HELPER.send(NewChild(pid, tx, deadline)); }
965 return match rx.recv_opt() {
967 Err(()) => Err(util::timeout("wait timed out")),
970 // Register a new SIGCHLD handler, returning the reading half of the
971 // self-pipe plus the old handler registered (return value of sigaction).
973 // Be sure to set up the self-pipe first because as soon as we register a
974 // handler we're going to start receiving signals.
975 fn register_sigchld() -> (libc::c_int, c::sigaction) {
977 let mut pipes = [0, ..2];
978 assert_eq!(libc::pipe(pipes.as_mut_ptr()), 0);
979 util::set_nonblocking(pipes[0], true).ok().unwrap();
980 util::set_nonblocking(pipes[1], true).ok().unwrap();
983 let mut old: c::sigaction = mem::zeroed();
984 let mut new: c::sigaction = mem::zeroed();
985 new.sa_handler = sigchld_handler;
986 new.sa_flags = c::SA_NOCLDSTOP;
987 assert_eq!(c::sigaction(c::SIGCHLD, &new, &mut old), 0);
992 // Helper thread for processing SIGCHLD messages
993 fn waitpid_helper(input: libc::c_int,
994 messages: Receiver<Req>,
995 (read_fd, old): (libc::c_int, c::sigaction)) {
996 util::set_nonblocking(input, true).ok().unwrap();
997 let mut set: c::fd_set = unsafe { mem::zeroed() };
998 let mut tv: libc::timeval;
999 let mut active = Vec::<(libc::pid_t, Sender<rtio::ProcessExit>, u64)>::new();
1000 let max = cmp::max(input, read_fd) + 1;
1003 // Figure out the timeout of our syscall-to-happen. If we're waiting
1004 // for some processes, then they'll have a timeout, otherwise we
1005 // wait indefinitely for a message to arrive.
1007 // FIXME: sure would be nice to not have to scan the entire array
1008 let min = active.iter().map(|a| *a.ref2()).enumerate().min_by(|p| {
1011 let (p, idx) = match min {
1012 Some((idx, deadline)) => {
1013 let now = ::io::timer::now();
1014 let ms = if now < deadline {deadline - now} else {0};
1015 tv = util::ms_to_timeval(ms);
1016 (&mut tv as *mut _, idx)
1018 None => (ptr::mut_null(), -1),
1021 // Wait for something to happen
1022 c::fd_set(&mut set, input);
1023 c::fd_set(&mut set, read_fd);
1024 match unsafe { c::select(max, &mut set, ptr::mut_null(),
1025 ptr::mut_null(), p) } {
1026 // interrupted, retry
1027 -1 if os::errno() == libc::EINTR as int => continue,
1029 // We read something, break out and process
1032 // Timeout, the pending request is removed
1034 drop(active.remove(idx));
1038 n => fail!("error in select {} ({})", os::errno(), n),
1041 // Process any pending messages
1044 match messages.try_recv() {
1045 Ok(NewChild(pid, tx, deadline)) => {
1046 active.push((pid, tx, deadline));
1048 Err(comm::Disconnected) => {
1049 assert!(active.len() == 0);
1052 Err(comm::Empty) => break,
1057 // If a child exited (somehow received SIGCHLD), then poll all
1058 // children to see if any of them exited.
1060 // We also attempt to be responsible netizens when dealing with
1061 // SIGCHLD by invoking any previous SIGCHLD handler instead of just
1062 // ignoring any previous SIGCHLD handler. Note that we don't provide
1063 // a 1:1 mapping of our handler invocations to the previous handler
1064 // invocations because we drain the `read_fd` entirely. This is
1065 // probably OK because the kernel is already allowed to coalesce
1066 // simultaneous signals, we're just doing some extra coalescing.
1068 // Another point of note is that this likely runs the signal handler
1069 // on a different thread than the one that received the signal. I
1070 // *think* this is ok at this time.
1072 // The main reason for doing this is to allow stdtest to run native
1073 // tests as well. Both libgreen and libnative are running around
1074 // with process timeouts, but libgreen should get there first
1075 // (currently libuv doesn't handle old signal handlers).
1077 let i: uint = unsafe { mem::transmute(old.sa_handler) };
1079 assert!(old.sa_flags & c::SA_SIGINFO == 0);
1080 (old.sa_handler)(c::SIGCHLD);
1083 // FIXME: sure would be nice to not have to scan the entire
1085 active.retain(|&(pid, ref tx, _)| {
1086 match waitpid_nowait(pid) {
1087 Some(msg) => { tx.send(msg); false }
1094 // Once this helper thread is done, we re-register the old sigchld
1095 // handler and close our intermediate file descriptors.
1097 assert_eq!(c::sigaction(c::SIGCHLD, &old, ptr::mut_null()), 0);
1098 let _ = libc::close(read_fd);
1099 let _ = libc::close(WRITE_FD);
1104 // Drain all pending data from the file descriptor, returning if any data
1105 // could be drained. This requires that the file descriptor is in
1106 // nonblocking mode.
1107 fn drain(fd: libc::c_int) -> bool {
1108 let mut ret = false;
1110 let mut buf = [0u8, ..1];
1112 libc::read(fd, buf.as_mut_ptr() as *mut libc::c_void,
1113 buf.len() as libc::size_t)
1115 n if n > 0 => { ret = true; }
1117 -1 if util::wouldblock() => return ret,
1118 n => fail!("bad read {} ({})", os::last_os_error(), n),
1123 // Signal handler for SIGCHLD signals, must be async-signal-safe!
1125 // This function will write to the writing half of the "self pipe" to wake
1126 // up the helper thread if it's waiting. Note that this write must be
1127 // nonblocking because if it blocks and the reader is the thread we
1128 // interrupted, then we'll deadlock.
1130 // When writing, if the write returns EWOULDBLOCK then we choose to ignore
1131 // it. At that point we're guaranteed that there's something in the pipe
1132 // which will wake up the other end at some point, so we just allow this
1133 // signal to be coalesced with the pending signals on the pipe.
1134 extern fn sigchld_handler(_signum: libc::c_int) {
1137 libc::write(WRITE_FD, &msg as *const _ as *const libc::c_void, 1)
1140 -1 if util::wouldblock() => {} // see above comments
1141 n => fail!("bad error on write fd: {} {}", n, os::errno()),
1146 fn waitpid_nowait(pid: pid_t) -> Option<rtio::ProcessExit> {
1147 return waitpid_os(pid);
1149 // This code path isn't necessary on windows
1151 fn waitpid_os(_pid: pid_t) -> Option<rtio::ProcessExit> { None }
1154 fn waitpid_os(pid: pid_t) -> Option<rtio::ProcessExit> {
1155 let mut status = 0 as c_int;
1156 match retry(|| unsafe {
1157 c::waitpid(pid, &mut status, c::WNOHANG)
1159 n if n == pid => Some(translate_status(status)),
1161 n => fail!("unknown waitpid error `{}`: {}", n,
1162 super::last_error().code),
1170 #[test] #[cfg(windows)]
1171 fn test_make_command_line() {
1173 use std::c_str::CString;
1174 use super::make_command_line;
1176 fn test_wrapper(prog: &str, args: &[&str]) -> String {
1177 make_command_line(&prog.to_c_str(),
1179 .map(|a| a.to_c_str())
1180 .collect::<Vec<CString>>()
1185 test_wrapper("prog", ["aaa", "bbb", "ccc"]),
1186 "prog aaa bbb ccc".to_string()
1190 test_wrapper("C:\\Program Files\\blah\\blah.exe", ["aaa"]),
1191 "\"C:\\Program Files\\blah\\blah.exe\" aaa".to_string()
1194 test_wrapper("C:\\Program Files\\test", ["aa\"bb"]),
1195 "\"C:\\Program Files\\test\" aa\\\"bb".to_string()
1198 test_wrapper("echo", ["a b c"]),
1199 "echo \"a b c\"".to_string()
1202 test_wrapper("\u03c0\u042f\u97f3\u00e6\u221e", []),
1203 "\u03c0\u042f\u97f3\u00e6\u221e".to_string()