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};
17 use std::rt::rtio::{ProcessConfig, IoResult, IoError};
18 use std::c_str::CString;
23 #[cfg(windows)] use std::string::String;
24 #[cfg(unix)] use super::c;
25 #[cfg(unix)] use super::retry;
26 #[cfg(unix)] use io::helper_thread::Helper;
29 helper_init!(static mut HELPER: Helper<Req>)
32 * A value representing a child process.
34 * The lifetime of this value is linked to the lifetime of the actual
35 * process - the Process destructor calls self.finish() which waits
36 * for the process to terminate.
39 /// The unique id of the process (this should never be negative).
42 /// A handle to the process - on unix this will always be NULL, but on
43 /// windows it will be a HANDLE to the process, which will prevent the
44 /// pid being re-used until the handle is closed.
47 /// None until finish() is called.
48 exit_code: Option<rtio::ProcessExit>,
50 /// Manually delivered signal
51 exit_signal: Option<int>,
53 /// Deadline after which wait() will return
59 NewChild(libc::pid_t, Sender<rtio::ProcessExit>, u64),
63 /// Creates a new process using native process-spawning abilities provided
64 /// by the OS. Operations on this process will be blocking instead of using
65 /// the runtime for sleeping just this current task.
66 pub fn spawn(cfg: ProcessConfig)
67 -> IoResult<(Process, Vec<Option<file::FileDesc>>)>
69 // right now we only handle stdin/stdout/stderr.
70 if cfg.extra_io.len() > 0 {
71 return Err(super::unimpl());
74 fn get_io(io: rtio::StdioContainer,
75 ret: &mut Vec<Option<file::FileDesc>>)
76 -> (Option<os::Pipe>, c_int)
79 rtio::Ignored => { ret.push(None); (None, -1) }
80 rtio::InheritFd(fd) => { ret.push(None); (None, fd) }
81 rtio::CreatePipe(readable, _writable) => {
82 let pipe = os::pipe();
83 let (theirs, ours) = if readable {
84 (pipe.input, pipe.out)
86 (pipe.out, pipe.input)
88 ret.push(Some(file::FileDesc::new(ours, true)));
94 let mut ret_io = Vec::new();
95 let (in_pipe, in_fd) = get_io(cfg.stdin, &mut ret_io);
96 let (out_pipe, out_fd) = get_io(cfg.stdout, &mut ret_io);
97 let (err_pipe, err_fd) = get_io(cfg.stderr, &mut ret_io);
99 let res = spawn_process_os(cfg, in_fd, out_fd, err_fd);
102 for pipe in in_pipe.iter() { let _ = libc::close(pipe.input); }
103 for pipe in out_pipe.iter() { let _ = libc::close(pipe.out); }
104 for pipe in err_pipe.iter() { let _ = libc::close(pipe.out); }
122 pub fn kill(pid: libc::pid_t, signum: int) -> IoResult<()> {
123 unsafe { killpid(pid, signum) }
127 impl rtio::RtioProcess for Process {
128 fn id(&self) -> pid_t { self.pid }
130 fn set_timeout(&mut self, timeout: Option<u64>) {
131 self.deadline = timeout.map(|i| i + ::io::timer::now()).unwrap_or(0);
134 fn wait(&mut self) -> IoResult<rtio::ProcessExit> {
135 match self.exit_code {
136 Some(code) => Ok(code),
138 let code = try!(waitpid(self.pid, self.deadline));
139 // On windows, waitpid will never return a signal. If a signal
140 // was successfully delivered to the process, however, we can
141 // consider it as having died via a signal.
142 let code = match self.exit_signal {
144 Some(signal) if cfg!(windows) => rtio::ExitSignal(signal),
147 self.exit_code = Some(code);
153 fn kill(&mut self, signum: int) -> IoResult<()> {
154 #[cfg(unix)] use ERROR = libc::EINVAL;
155 #[cfg(windows)] use ERROR = libc::ERROR_NOTHING_TO_TERMINATE;
157 // On linux (and possibly other unices), a process that has exited will
158 // continue to accept signals because it is "defunct". The delivery of
159 // signals will only fail once the child has been reaped. For this
160 // reason, if the process hasn't exited yet, then we attempt to collect
161 // their status with WNOHANG.
162 if self.exit_code.is_none() {
163 match waitpid_nowait(self.pid) {
164 Some(code) => { self.exit_code = Some(code); }
169 // if the process has finished, and therefore had waitpid called,
170 // and we kill it, then on unix we might ending up killing a
171 // newer process that happens to have the same (re-used) id
172 match self.exit_code {
173 Some(..) => return Err(IoError {
176 detail: Some("can't kill an exited process".to_str()),
181 // A successfully delivered signal that isn't 0 (just a poll for being
182 // alive) is recorded for windows (see wait())
183 match unsafe { killpid(self.pid, signum) } {
184 Ok(()) if signum == 0 => Ok(()),
185 Ok(()) => { self.exit_signal = Some(signum); Ok(()) }
191 impl Drop for Process {
193 free_handle(self.handle);
198 unsafe fn killpid(pid: pid_t, signal: int) -> IoResult<()> {
199 let handle = libc::OpenProcess(libc::PROCESS_TERMINATE |
200 libc::PROCESS_QUERY_INFORMATION,
201 libc::FALSE, pid as libc::DWORD);
202 if handle.is_null() {
203 return Err(super::last_error())
205 let ret = match signal {
206 // test for existence on signal 0
209 let ret = libc::GetExitCodeProcess(handle, &mut status);
211 Err(super::last_error())
212 } else if status != libc::STILL_ACTIVE {
214 code: libc::ERROR_NOTHING_TO_TERMINATE as uint,
222 15 | 9 => { // sigterm or sigkill
223 let ret = libc::TerminateProcess(handle, 1);
224 super::mkerr_winbool(ret)
227 code: libc::ERROR_CALL_NOT_IMPLEMENTED as uint,
229 detail: Some("unsupported signal on windows".to_string()),
232 let _ = libc::CloseHandle(handle);
237 unsafe fn killpid(pid: pid_t, signal: int) -> IoResult<()> {
238 let r = libc::funcs::posix88::signal::kill(pid, signal as c_int);
242 struct SpawnProcessResult {
248 fn spawn_process_os(cfg: ProcessConfig,
249 in_fd: c_int, out_fd: c_int, err_fd: c_int)
250 -> IoResult<SpawnProcessResult> {
251 use libc::types::os::arch::extra::{DWORD, HANDLE, STARTUPINFO};
252 use libc::consts::os::extra::{
254 STARTF_USESTDHANDLES,
255 INVALID_HANDLE_VALUE,
256 DUPLICATE_SAME_ACCESS
258 use libc::funcs::extra::kernel32::{
264 use libc::funcs::extra::msvcrt::get_osfhandle;
268 if cfg.gid.is_some() || cfg.uid.is_some() {
270 code: libc::ERROR_CALL_NOT_IMPLEMENTED as uint,
272 detail: Some("unsupported gid/uid requested on windows".to_str()),
277 let mut si = zeroed_startupinfo();
278 si.cb = mem::size_of::<STARTUPINFO>() as DWORD;
279 si.dwFlags = STARTF_USESTDHANDLES;
281 let cur_proc = GetCurrentProcess();
283 // Similarly to unix, we don't actually leave holes for the stdio file
284 // descriptors, but rather open up /dev/null equivalents. These
285 // equivalents are drawn from libuv's windows process spawning.
286 let set_fd = |fd: c_int, slot: &mut HANDLE, is_stdin: bool| {
288 let access = if is_stdin {
289 libc::FILE_GENERIC_READ
291 libc::FILE_GENERIC_WRITE | libc::FILE_READ_ATTRIBUTES
293 let size = mem::size_of::<libc::SECURITY_ATTRIBUTES>();
294 let mut sa = libc::SECURITY_ATTRIBUTES {
295 nLength: size as libc::DWORD,
296 lpSecurityDescriptor: ptr::mut_null(),
299 let filename = "NUL".to_utf16().append_one(0);
300 *slot = libc::CreateFileW(filename.as_ptr(),
302 libc::FILE_SHARE_READ |
303 libc::FILE_SHARE_WRITE,
308 if *slot == INVALID_HANDLE_VALUE as libc::HANDLE {
309 return Err(super::last_error())
312 let orig = get_osfhandle(fd) as HANDLE;
313 if orig == INVALID_HANDLE_VALUE as HANDLE {
314 return Err(super::last_error())
316 if DuplicateHandle(cur_proc, orig, cur_proc, slot,
317 0, TRUE, DUPLICATE_SAME_ACCESS) == FALSE {
318 return Err(super::last_error())
324 try!(set_fd(in_fd, &mut si.hStdInput, true));
325 try!(set_fd(out_fd, &mut si.hStdOutput, false));
326 try!(set_fd(err_fd, &mut si.hStdError, false));
328 let cmd_str = make_command_line(cfg.program, cfg.args);
329 let mut pi = zeroed_process_information();
330 let mut create_err = None;
332 // stolen from the libuv code.
333 let mut flags = libc::CREATE_UNICODE_ENVIRONMENT;
335 flags |= libc::DETACHED_PROCESS | libc::CREATE_NEW_PROCESS_GROUP;
338 with_envp(cfg.env, |envp| {
339 with_dirp(cfg.cwd, |dirp| {
340 let mut cmd_str = cmd_str.to_utf16().append_one(0);
341 let created = CreateProcessW(ptr::null(),
342 cmd_str.as_mut_ptr(),
348 if created == FALSE {
349 create_err = Some(super::last_error());
354 assert!(CloseHandle(si.hStdInput) != 0);
355 assert!(CloseHandle(si.hStdOutput) != 0);
356 assert!(CloseHandle(si.hStdError) != 0);
359 Some(err) => return Err(err),
363 // We close the thread handle because we don't care about keeping the
364 // thread id valid, and we aren't keeping the thread handle around to be
365 // able to close it later. We don't close the process handle however
366 // because std::we want the process id to stay valid at least until the
367 // calling code closes the process handle.
368 assert!(CloseHandle(pi.hThread) != 0);
370 Ok(SpawnProcessResult {
371 pid: pi.dwProcessId as pid_t,
372 handle: pi.hProcess as *()
378 fn zeroed_startupinfo() -> libc::types::os::arch::extra::STARTUPINFO {
379 libc::types::os::arch::extra::STARTUPINFO {
381 lpReserved: ptr::mut_null(),
382 lpDesktop: ptr::mut_null(),
383 lpTitle: ptr::mut_null(),
394 lpReserved2: ptr::mut_null(),
395 hStdInput: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
396 hStdOutput: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
397 hStdError: libc::INVALID_HANDLE_VALUE as libc::HANDLE,
402 fn zeroed_process_information() -> libc::types::os::arch::extra::PROCESS_INFORMATION {
403 libc::types::os::arch::extra::PROCESS_INFORMATION {
404 hProcess: ptr::mut_null(),
405 hThread: ptr::mut_null(),
412 fn make_command_line(prog: &CString, args: &[CString]) -> String {
413 let mut cmd = String::new();
414 append_arg(&mut cmd, prog.as_str()
415 .expect("expected program name to be utf-8 encoded"));
416 for arg in args.iter() {
418 append_arg(&mut cmd, arg.as_str()
419 .expect("expected argument to be utf-8 encoded"));
423 fn append_arg(cmd: &mut String, arg: &str) {
424 let quote = arg.chars().any(|c| c == ' ' || c == '\t');
428 let argvec: Vec<char> = arg.chars().collect();
429 for i in range(0u, argvec.len()) {
430 append_char_at(cmd, &argvec, i);
437 fn append_char_at(cmd: &mut String, arg: &Vec<char>, i: uint) {
441 cmd.push_str("\\\"");
444 if backslash_run_ends_in_quote(arg, i) {
445 // Double all backslashes that are in runs before quotes.
446 cmd.push_str("\\\\");
448 // Pass other backslashes through unescaped.
458 fn backslash_run_ends_in_quote(s: &Vec<char>, mut i: uint) -> bool {
459 while i < s.len() && *s.get(i) == '\\' {
462 return i < s.len() && *s.get(i) == '"';
467 fn spawn_process_os(cfg: ProcessConfig, in_fd: c_int, out_fd: c_int, err_fd: c_int)
468 -> IoResult<SpawnProcessResult>
470 use libc::funcs::posix88::unistd::{fork, dup2, close, chdir, execvp};
471 use libc::funcs::bsd44::getdtablesize;
476 pub fn rust_unset_sigprocmask();
480 #[cfg(target_os = "macos")]
481 unsafe fn set_environ(envp: *c_void) {
482 extern { fn _NSGetEnviron() -> *mut *c_void; }
484 *_NSGetEnviron() = envp;
486 #[cfg(not(target_os = "macos"))]
487 unsafe fn set_environ(envp: *c_void) {
488 extern { static mut environ: *c_void; }
492 unsafe fn set_cloexec(fd: c_int) {
493 let ret = c::ioctl(fd, c::FIOCLEX);
497 let dirp = cfg.cwd.map(|c| c.with_ref(|p| p)).unwrap_or(ptr::null());
499 with_envp(cfg.env, proc(envp) {
500 with_argv(cfg.program, cfg.args, proc(argv) unsafe {
501 let pipe = os::pipe();
502 let mut input = file::FileDesc::new(pipe.input, true);
503 let mut output = file::FileDesc::new(pipe.out, true);
505 // We may use this in the child, so perform allocations before the
507 let devnull = "/dev/null".to_c_str();
509 set_cloexec(output.fd());
513 fail!("failure in fork: {}", os::last_os_error());
516 let mut bytes = [0, ..4];
517 return match input.inner_read(bytes) {
519 let errno = (bytes[0] << 24) as i32 |
520 (bytes[1] << 16) as i32 |
521 (bytes[2] << 8) as i32 |
522 (bytes[3] << 0) as i32;
530 Ok(SpawnProcessResult {
535 Ok(..) => fail!("short read on the cloexec pipe"),
538 // And at this point we've reached a special time in the life of the
539 // child. The child must now be considered hamstrung and unable to
540 // do anything other than syscalls really. Consider the following
543 // 1. Thread A of process 1 grabs the malloc() mutex
544 // 2. Thread B of process 1 forks(), creating thread C
545 // 3. Thread C of process 2 then attempts to malloc()
546 // 4. The memory of process 2 is the same as the memory of
547 // process 1, so the mutex is locked.
549 // This situation looks a lot like deadlock, right? It turns out
550 // that this is what pthread_atfork() takes care of, which is
551 // presumably implemented across platforms. The first thing that
552 // threads to *before* forking is to do things like grab the malloc
553 // mutex, and then after the fork they unlock it.
555 // Despite this information, libnative's spawn has been witnessed to
556 // deadlock on both OSX and FreeBSD. I'm not entirely sure why, but
557 // all collected backtraces point at malloc/free traffic in the
558 // child spawned process.
560 // For this reason, the block of code below should contain 0
561 // invocations of either malloc of free (or their related friends).
563 // As an example of not having malloc/free traffic, we don't close
564 // this file descriptor by dropping the FileDesc (which contains an
565 // allocation). Instead we just close it manually. This will never
566 // have the drop glue anyway because this code never returns (the
567 // child will either exec() or invoke libc::exit)
568 let _ = libc::close(input.fd());
570 fn fail(output: &mut file::FileDesc) -> ! {
571 let errno = os::errno();
578 assert!(output.inner_write(bytes).is_ok());
579 unsafe { libc::_exit(1) }
582 rustrt::rust_unset_sigprocmask();
584 // If a stdio file descriptor is set to be ignored (via a -1 file
585 // descriptor), then we don't actually close it, but rather open
586 // up /dev/null into that file descriptor. Otherwise, the first file
587 // descriptor opened up in the child would be numbered as one of the
588 // stdio file descriptors, which is likely to wreak havoc.
589 let setup = |src: c_int, dst: c_int| {
590 let src = if src == -1 {
591 let flags = if dst == libc::STDIN_FILENO {
596 devnull.with_ref(|p| libc::open(p, flags, 0))
600 src != -1 && retry(|| dup2(src, dst)) != -1
603 if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
604 if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
605 if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
607 // close all other fds
608 for fd in range(3, getdtablesize()).rev() {
609 if fd != output.fd() {
610 let _ = close(fd as c_int);
616 if libc::setgid(u as libc::gid_t) != 0 {
624 // When dropping privileges from root, the `setgroups` call will
625 // remove any extraneous groups. If we don't call this, then
626 // even though our uid has dropped, we may still have groups
627 // that enable us to do super-user things. This will fail if we
628 // aren't root, so don't bother checking the return value, this
629 // is just done as an optimistic privilege dropping function.
631 fn setgroups(ngroups: libc::c_int,
632 ptr: *libc::c_void) -> libc::c_int;
634 let _ = setgroups(0, 0 as *libc::c_void);
636 if libc::setuid(u as libc::uid_t) != 0 {
643 // Don't check the error of setsid because it fails if we're the
644 // process leader already. We just forked so it shouldn't return
645 // error, but ignore it anyway.
646 let _ = libc::setsid();
648 if !dirp.is_null() && chdir(dirp) == -1 {
654 let _ = execvp(*argv, argv);
661 fn with_argv<T>(prog: &CString, args: &[CString], cb: proc(**libc::c_char) -> T) -> T {
662 let mut ptrs: Vec<*libc::c_char> = Vec::with_capacity(args.len()+1);
664 // Convert the CStrings into an array of pointers. Note: the
665 // lifetime of the various CStrings involved is guaranteed to be
666 // larger than the lifetime of our invocation of cb, but this is
667 // technically unsafe as the callback could leak these pointers
669 ptrs.push(prog.with_ref(|buf| buf));
670 ptrs.extend(args.iter().map(|tmp| tmp.with_ref(|buf| buf)));
672 // Add a terminating null pointer (required by libc).
673 ptrs.push(ptr::null());
679 fn with_envp<T>(env: Option<&[(CString, CString)]>, cb: proc(*c_void) -> T) -> T {
680 // On posixy systems we can pass a char** for envp, which is a
681 // null-terminated array of "k=v\0" strings. Since we must create
682 // these strings locally, yet expose a raw pointer to them, we
683 // create a temporary vector to own the CStrings that outlives the
687 let mut tmps = Vec::with_capacity(env.len());
689 for pair in env.iter() {
690 let mut kv = Vec::new();
691 kv.push_all(pair.ref0().as_bytes_no_nul());
693 kv.push_all(pair.ref1().as_bytes()); // includes terminal \0
697 // As with `with_argv`, this is unsafe, since cb could leak the pointers.
698 let mut ptrs: Vec<*libc::c_char> =
700 .map(|tmp| tmp.as_ptr() as *libc::c_char)
702 ptrs.push(ptr::null());
704 cb(ptrs.as_ptr() as *c_void)
711 fn with_envp<T>(env: Option<&[(CString, CString)]>, cb: |*mut c_void| -> T) -> T {
712 // On win32 we pass an "environment block" which is not a char**, but
713 // rather a concatenation of null-terminated k=v\0 sequences, with a final
717 let mut blk = Vec::new();
719 for pair in env.iter() {
720 let kv = format!("{}={}",
721 pair.ref0().as_str().unwrap(),
722 pair.ref1().as_str().unwrap());
723 blk.push_all(kv.to_utf16().as_slice());
729 cb(blk.as_mut_ptr() as *mut c_void)
731 _ => cb(ptr::mut_null())
736 fn with_dirp<T>(d: Option<&CString>, cb: |*u16| -> T) -> T {
739 let dir_str = dir.as_str()
740 .expect("expected workingdirectory to be utf-8 encoded");
741 let dir_str = dir_str.to_utf16().append_one(0);
744 None => cb(ptr::null())
749 fn free_handle(handle: *()) {
751 libc::CloseHandle(mem::transmute(handle)) != 0
756 fn free_handle(_handle: *()) {
757 // unix has no process handle object, just a pid
761 fn translate_status(status: c_int) -> rtio::ProcessExit {
762 #![allow(non_snake_case_functions)]
763 #[cfg(target_os = "linux")]
764 #[cfg(target_os = "android")]
766 pub fn WIFEXITED(status: i32) -> bool { (status & 0xff) == 0 }
767 pub fn WEXITSTATUS(status: i32) -> i32 { (status >> 8) & 0xff }
768 pub fn WTERMSIG(status: i32) -> i32 { status & 0x7f }
771 #[cfg(target_os = "macos")]
772 #[cfg(target_os = "ios")]
773 #[cfg(target_os = "freebsd")]
775 pub fn WIFEXITED(status: i32) -> bool { (status & 0x7f) == 0 }
776 pub fn WEXITSTATUS(status: i32) -> i32 { status >> 8 }
777 pub fn WTERMSIG(status: i32) -> i32 { status & 0o177 }
780 if imp::WIFEXITED(status) {
781 rtio::ExitStatus(imp::WEXITSTATUS(status) as int)
783 rtio::ExitSignal(imp::WTERMSIG(status) as int)
788 * Waits for a process to exit and returns the exit code, failing
789 * if there is no process with the specified id.
791 * Note that this is private to avoid race conditions on unix where if
792 * a user calls waitpid(some_process.get_id()) then some_process.finish()
793 * and some_process.destroy() and some_process.finalize() will then either
794 * operate on a none-existent process or, even worse, on a newer process
798 fn waitpid(pid: pid_t, deadline: u64) -> IoResult<rtio::ProcessExit> {
799 use libc::types::os::arch::extra::DWORD;
800 use libc::consts::os::extra::{
802 PROCESS_QUERY_INFORMATION,
809 use libc::funcs::extra::kernel32::{
817 let process = OpenProcess(SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
820 if process.is_null() {
821 return Err(super::last_error())
826 if GetExitCodeProcess(process, &mut status) == FALSE {
827 let err = Err(super::last_error());
828 assert!(CloseHandle(process) != 0);
831 if status != STILL_ACTIVE {
832 assert!(CloseHandle(process) != 0);
833 return Ok(rtio::ExitStatus(status as int));
835 let interval = if deadline == 0 {
838 let now = ::io::timer::now();
839 if deadline < now {0} else {(deadline - now) as u32}
841 match WaitForSingleObject(process, interval) {
844 assert!(CloseHandle(process) != 0);
845 return Err(util::timeout("process wait timed out"))
848 let err = Err(super::last_error());
849 assert!(CloseHandle(process) != 0);
858 fn waitpid(pid: pid_t, deadline: u64) -> IoResult<rtio::ProcessExit> {
862 static mut WRITE_FD: libc::c_int = 0;
864 let mut status = 0 as c_int;
866 return match retry(|| unsafe { c::waitpid(pid, &mut status, 0) }) {
867 -1 => fail!("unknown waitpid error: {}", super::last_error().code),
868 _ => Ok(translate_status(status)),
872 // On unix, wait() and its friends have no timeout parameters, so there is
873 // no way to time out a thread in wait(). From some googling and some
874 // thinking, it appears that there are a few ways to handle timeouts in
875 // wait(), but the only real reasonable one for a multi-threaded program is
876 // to listen for SIGCHLD.
878 // With this in mind, the waiting mechanism with a timeout barely uses
879 // waitpid() at all. There are a few times that waitpid() is invoked with
880 // WNOHANG, but otherwise all the necessary blocking is done by waiting for
881 // a SIGCHLD to arrive (and that blocking has a timeout). Note, however,
882 // that waitpid() is still used to actually reap the child.
884 // Signal handling is super tricky in general, and this is no exception. Due
885 // to the async nature of SIGCHLD, we use the self-pipe trick to transmit
886 // data out of the signal handler to the rest of the application. The first
887 // idea would be to have each thread waiting with a timeout to read this
888 // output file descriptor, but a write() is akin to a signal(), not a
889 // broadcast(), so it would only wake up one thread, and possibly the wrong
890 // thread. Hence a helper thread is used.
892 // The helper thread here is responsible for farming requests for a
893 // waitpid() with a timeout, and then processing all of the wait requests.
894 // By guaranteeing that only this helper thread is reading half of the
895 // self-pipe, we're sure that we'll never lose a SIGCHLD. This helper thread
896 // is also responsible for select() to wait for incoming messages or
897 // incoming SIGCHLD messages, along with passing an appropriate timeout to
898 // select() to wake things up as necessary.
900 // The ordering of the following statements is also very purposeful. First,
901 // we must be guaranteed that the helper thread is booted and available to
902 // receive SIGCHLD signals, and then we must also ensure that we do a
903 // nonblocking waitpid() at least once before we go ask the sigchld helper.
904 // This prevents the race where the child exits, we boot the helper, and
905 // then we ask for the child's exit status (never seeing a sigchld).
907 // The actual communication between the helper thread and this thread is
908 // quite simple, just a channel moving data around.
910 unsafe { HELPER.boot(register_sigchld, waitpid_helper) }
912 match waitpid_nowait(pid) {
913 Some(ret) => return Ok(ret),
917 let (tx, rx) = channel();
918 unsafe { HELPER.send(NewChild(pid, tx, deadline)); }
919 return match rx.recv_opt() {
921 Err(()) => Err(util::timeout("wait timed out")),
924 // Register a new SIGCHLD handler, returning the reading half of the
925 // self-pipe plus the old handler registered (return value of sigaction).
927 // Be sure to set up the self-pipe first because as soon as we register a
928 // handler we're going to start receiving signals.
929 fn register_sigchld() -> (libc::c_int, c::sigaction) {
931 let mut pipes = [0, ..2];
932 assert_eq!(libc::pipe(pipes.as_mut_ptr()), 0);
933 util::set_nonblocking(pipes[0], true).ok().unwrap();
934 util::set_nonblocking(pipes[1], true).ok().unwrap();
937 let mut old: c::sigaction = mem::zeroed();
938 let mut new: c::sigaction = mem::zeroed();
939 new.sa_handler = sigchld_handler;
940 new.sa_flags = c::SA_NOCLDSTOP;
941 assert_eq!(c::sigaction(c::SIGCHLD, &new, &mut old), 0);
946 // Helper thread for processing SIGCHLD messages
947 fn waitpid_helper(input: libc::c_int,
948 messages: Receiver<Req>,
949 (read_fd, old): (libc::c_int, c::sigaction)) {
950 util::set_nonblocking(input, true).ok().unwrap();
951 let mut set: c::fd_set = unsafe { mem::zeroed() };
952 let mut tv: libc::timeval;
953 let mut active = Vec::<(libc::pid_t, Sender<rtio::ProcessExit>, u64)>::new();
954 let max = cmp::max(input, read_fd) + 1;
957 // Figure out the timeout of our syscall-to-happen. If we're waiting
958 // for some processes, then they'll have a timeout, otherwise we
959 // wait indefinitely for a message to arrive.
961 // FIXME: sure would be nice to not have to scan the entire array
962 let min = active.iter().map(|a| *a.ref2()).enumerate().min_by(|p| {
965 let (p, idx) = match min {
966 Some((idx, deadline)) => {
967 let now = ::io::timer::now();
968 let ms = if now < deadline {deadline - now} else {0};
969 tv = util::ms_to_timeval(ms);
972 None => (ptr::null(), -1),
975 // Wait for something to happen
976 c::fd_set(&mut set, input);
977 c::fd_set(&mut set, read_fd);
978 match unsafe { c::select(max, &set, ptr::null(), ptr::null(), p) } {
979 // interrupted, retry
980 -1 if os::errno() == libc::EINTR as int => continue,
982 // We read something, break out and process
985 // Timeout, the pending request is removed
987 drop(active.remove(idx));
991 n => fail!("error in select {} ({})", os::errno(), n),
994 // Process any pending messages
997 match messages.try_recv() {
998 Ok(NewChild(pid, tx, deadline)) => {
999 active.push((pid, tx, deadline));
1001 Err(comm::Disconnected) => {
1002 assert!(active.len() == 0);
1005 Err(comm::Empty) => break,
1010 // If a child exited (somehow received SIGCHLD), then poll all
1011 // children to see if any of them exited.
1013 // We also attempt to be responsible netizens when dealing with
1014 // SIGCHLD by invoking any previous SIGCHLD handler instead of just
1015 // ignoring any previous SIGCHLD handler. Note that we don't provide
1016 // a 1:1 mapping of our handler invocations to the previous handler
1017 // invocations because we drain the `read_fd` entirely. This is
1018 // probably OK because the kernel is already allowed to coalesce
1019 // simultaneous signals, we're just doing some extra coalescing.
1021 // Another point of note is that this likely runs the signal handler
1022 // on a different thread than the one that received the signal. I
1023 // *think* this is ok at this time.
1025 // The main reason for doing this is to allow stdtest to run native
1026 // tests as well. Both libgreen and libnative are running around
1027 // with process timeouts, but libgreen should get there first
1028 // (currently libuv doesn't handle old signal handlers).
1030 let i: uint = unsafe { mem::transmute(old.sa_handler) };
1032 assert!(old.sa_flags & c::SA_SIGINFO == 0);
1033 (old.sa_handler)(c::SIGCHLD);
1036 // FIXME: sure would be nice to not have to scan the entire
1038 active.retain(|&(pid, ref tx, _)| {
1039 match waitpid_nowait(pid) {
1040 Some(msg) => { tx.send(msg); false }
1047 // Once this helper thread is done, we re-register the old sigchld
1048 // handler and close our intermediate file descriptors.
1050 assert_eq!(c::sigaction(c::SIGCHLD, &old, ptr::mut_null()), 0);
1051 let _ = libc::close(read_fd);
1052 let _ = libc::close(WRITE_FD);
1057 // Drain all pending data from the file descriptor, returning if any data
1058 // could be drained. This requires that the file descriptor is in
1059 // nonblocking mode.
1060 fn drain(fd: libc::c_int) -> bool {
1061 let mut ret = false;
1063 let mut buf = [0u8, ..1];
1065 libc::read(fd, buf.as_mut_ptr() as *mut libc::c_void,
1066 buf.len() as libc::size_t)
1068 n if n > 0 => { ret = true; }
1070 -1 if util::wouldblock() => return ret,
1071 n => fail!("bad read {} ({})", os::last_os_error(), n),
1076 // Signal handler for SIGCHLD signals, must be async-signal-safe!
1078 // This function will write to the writing half of the "self pipe" to wake
1079 // up the helper thread if it's waiting. Note that this write must be
1080 // nonblocking because if it blocks and the reader is the thread we
1081 // interrupted, then we'll deadlock.
1083 // When writing, if the write returns EWOULDBLOCK then we choose to ignore
1084 // it. At that point we're guaranteed that there's something in the pipe
1085 // which will wake up the other end at some point, so we just allow this
1086 // signal to be coalesced with the pending signals on the pipe.
1087 extern fn sigchld_handler(_signum: libc::c_int) {
1090 libc::write(WRITE_FD, &mut msg as *mut _ as *libc::c_void, 1)
1093 -1 if util::wouldblock() => {} // see above comments
1094 n => fail!("bad error on write fd: {} {}", n, os::errno()),
1099 fn waitpid_nowait(pid: pid_t) -> Option<rtio::ProcessExit> {
1100 return waitpid_os(pid);
1102 // This code path isn't necessary on windows
1104 fn waitpid_os(_pid: pid_t) -> Option<rtio::ProcessExit> { None }
1107 fn waitpid_os(pid: pid_t) -> Option<rtio::ProcessExit> {
1108 let mut status = 0 as c_int;
1109 match retry(|| unsafe {
1110 c::waitpid(pid, &mut status, c::WNOHANG)
1112 n if n == pid => Some(translate_status(status)),
1114 n => fail!("unknown waitpid error `{}`: {}", n,
1115 super::last_error().code),
1123 #[test] #[cfg(windows)]
1124 fn test_make_command_line() {
1126 use std::c_str::CString;
1127 use super::make_command_line;
1129 fn test_wrapper(prog: &str, args: &[&str]) -> String {
1130 make_command_line(&prog.to_c_str(),
1132 .map(|a| a.to_c_str())
1133 .collect::<Vec<CString>>()
1138 test_wrapper("prog", ["aaa", "bbb", "ccc"]),
1139 "prog aaa bbb ccc".to_string()
1143 test_wrapper("C:\\Program Files\\blah\\blah.exe", ["aaa"]),
1144 "\"C:\\Program Files\\blah\\blah.exe\" aaa".to_string()
1147 test_wrapper("C:\\Program Files\\test", ["aa\"bb"]),
1148 "\"C:\\Program Files\\test\" aa\\\"bb".to_string()
1151 test_wrapper("echo", ["a b c"]),
1152 "echo \"a b c\"".to_string()
1155 test_wrapper("\u03c0\u042f\u97f3\u00e6\u221e", []),
1156 "\u03c0\u042f\u97f3\u00e6\u221e".to_string()