2 * Copyright 2015 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 * Subprocess library, modeled after Python's subprocess module
19 * (http://docs.python.org/2/library/subprocess.html)
21 * This library defines one class (Subprocess) which represents a child
22 * process. Subprocess has two constructors: one that takes a vector<string>
23 * and executes the given executable without using the shell, and one
24 * that takes a string and executes the given command using the shell.
25 * Subprocess allows you to redirect the child's standard input, standard
26 * output, and standard error to/from child descriptors in the parent,
27 * or to create communication pipes between the child and the parent.
29 * The simplest example is a thread-safe [1] version of the system() library
31 * Subprocess(cmd).wait();
32 * which executes the command using the default shell and waits for it
33 * to complete, returning the exit status.
35 * A thread-safe [1] version of popen() (type="r", to read from the child):
36 * Subprocess proc(cmd, Subprocess::pipeStdout());
37 * // read from proc.stdout()
40 * A thread-safe [1] version of popen() (type="w", to write to the child):
41 * Subprocess proc(cmd, Subprocess::pipeStdin());
42 * // write to proc.stdin()
45 * If you want to redirect both stdin and stdout to pipes, you can, but note
46 * that you're subject to a variety of deadlocks. You'll want to use
47 * nonblocking I/O, like the callback version of communicate().
49 * The string or IOBuf-based variants of communicate() are the simplest way
50 * to communicate with a child via its standard input, standard output, and
51 * standard error. They buffer everything in memory, so they are not great
52 * for large amounts of data (or long-running processes), but they are much
53 * simpler than the callback version.
55 * == A note on thread-safety ==
57 * [1] "thread-safe" refers ONLY to the fact that Subprocess is very careful
58 * to fork in a way that does not cause grief in multithreaded programs.
60 * Caveat: If your system does not have the atomic pipe2 system call, it is
61 * not safe to concurrently call Subprocess from different threads.
62 * Therefore, it is best to have a single thread be responsible for spawning
65 * A particular instances of Subprocess is emphatically **not** thread-safe.
66 * If you need to simultaneously communicate via the pipes, and interact
67 * with the Subprocess state, your best bet is to:
68 * - takeOwnershipOfPipes() to separate the pipe I/O from the subprocess.
69 * - Only interact with the Subprocess from one thread at a time.
71 * The current implementation of communicate() cannot be safely interrupted.
72 * To do so correctly, one would need to use EventFD, or open a dedicated
73 * pipe to be messaged from a different thread -- in particular, kill() will
74 * not do, since a descendant may keep the pipes open indefinitely.
76 * So, once you call communicate(), you must wait for it to return, and not
77 * touch the pipes from other threads. closeParentFd() is emphatically
78 * unsafe to call concurrently, and even sendSignal() is not a good idea.
79 * You can perhaps give the Subprocess's PID to a different thread before
80 * starting communicate(), and use that PID to send a signal without
81 * accessing the Subprocess object. In that case, you will need a mutex
82 * that ensures you don't wait() before you sent said signal. In a
83 * nutshell, don't do this.
85 * In fact, signals are inherently concurrency-unsafe on Unix: if you signal
86 * a PID, while another thread is in waitpid(), the signal may fire either
87 * before or after the process is reaped. This means that your signal can,
88 * in pathological circumstances, be delivered to the wrong process (ouch!).
89 * To avoid this, you should only use non-blocking waits (i.e. poll()), and
90 * make sure to serialize your signals (i.e. kill()) with the waits --
91 * either wait & signal from the same thread, or use a mutex.
93 #ifndef FOLLY_SUBPROCESS_H_
94 #define FOLLY_SUBPROCESS_H_
96 #include <sys/types.h>
108 #include <boost/container/flat_map.hpp>
109 #include <boost/operators.hpp>
111 #include <folly/File.h>
112 #include <folly/FileUtil.h>
113 #include <folly/gen/String.h>
114 #include <folly/io/IOBufQueue.h>
115 #include <folly/MapUtil.h>
116 #include <folly/Portability.h>
117 #include <folly/Range.h>
122 * Class to wrap a process return code.
125 class ProcessReturnCode {
126 friend class Subprocess;
129 // Subprocess starts in the constructor, so this state designates only
130 // default-initialized or moved-out ProcessReturnCodes.
137 // Default-initialized for convenience. Subprocess::returnCode() will
138 // never produce this value.
139 ProcessReturnCode() : ProcessReturnCode(RV_NOT_STARTED) {}
141 // Trivially copyable
142 ProcessReturnCode(const ProcessReturnCode& p) = default;
143 ProcessReturnCode& operator=(const ProcessReturnCode& p) = default;
144 // Non-default move: In order for Subprocess to be movable, the "moved
145 // out" state must not be "running", or ~Subprocess() will abort.
146 ProcessReturnCode(ProcessReturnCode&& p) noexcept;
147 ProcessReturnCode& operator=(ProcessReturnCode&& p) noexcept;
150 * Process state. One of:
151 * NOT_STARTED: process hasn't been started successfully
152 * RUNNING: process is currently running
153 * EXITED: process exited (successfully or not)
154 * KILLED: process was killed by a signal.
159 * Helper wrappers around state().
161 bool notStarted() const { return state() == NOT_STARTED; }
162 bool running() const { return state() == RUNNING; }
163 bool exited() const { return state() == EXITED; }
164 bool killed() const { return state() == KILLED; }
167 * Exit status. Only valid if state() == EXITED; throws otherwise.
169 int exitStatus() const;
172 * Signal that caused the process's termination. Only valid if
173 * state() == KILLED; throws otherwise.
175 int killSignal() const;
178 * Was a core file generated? Only valid if state() == KILLED; throws
181 bool coreDumped() const;
184 * String representation; one of
187 * "exited with status <status>"
188 * "killed by signal <signal>"
189 * "killed by signal <signal> (core dumped)"
191 std::string str() const;
194 * Helper function to enforce a precondition based on this.
195 * Throws std::logic_error if in an unexpected state.
197 void enforce(State state) const;
199 explicit ProcessReturnCode(int rv) : rawStatus_(rv) { }
200 static constexpr int RV_NOT_STARTED = -2;
201 static constexpr int RV_RUNNING = -1;
207 * Base exception thrown by the Subprocess methods.
209 class SubprocessError : public std::exception {};
212 * Exception thrown by *Checked methods of Subprocess.
214 class CalledProcessError : public SubprocessError {
216 explicit CalledProcessError(ProcessReturnCode rc);
217 ~CalledProcessError() throw() = default;
218 const char* what() const throw() override { return what_.c_str(); }
219 ProcessReturnCode returnCode() const { return returnCode_; }
221 ProcessReturnCode returnCode_;
226 * Exception thrown if the subprocess cannot be started.
228 class SubprocessSpawnError : public SubprocessError {
230 SubprocessSpawnError(const char* executable, int errCode, int errnoValue);
231 ~SubprocessSpawnError() throw() = default;
232 const char* what() const throw() override { return what_.c_str(); }
233 int errnoValue() const { return errnoValue_; }
245 static const int CLOSE = -1;
246 static const int PIPE = -2;
247 static const int PIPE_IN = -3;
248 static const int PIPE_OUT = -4;
251 * Class representing various options: file descriptor behavior, and
252 * whether to use $PATH for searching for the executable,
254 * By default, we don't use $PATH, file descriptors are closed if
255 * the close-on-exec flag is set (fcntl FD_CLOEXEC) and inherited
258 class Options : private boost::orable<Options> {
259 friend class Subprocess;
261 Options() {} // E.g. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58328
264 * Change action for file descriptor fd.
266 * "action" may be another file descriptor number (dup2()ed before the
267 * child execs), or one of CLOSE, PIPE_IN, and PIPE_OUT.
269 * CLOSE: close the file descriptor in the child
270 * PIPE_IN: open a pipe *from* the child
271 * PIPE_OUT: open a pipe *to* the child
273 * PIPE is a shortcut; same as PIPE_IN for stdin (fd 0), same as
274 * PIPE_OUT for stdout (fd 1) or stderr (fd 2), and an error for
275 * other file descriptors.
277 Options& fd(int fd, int action);
280 * Shortcut to change the action for standard input.
282 Options& stdin(int action) { return fd(STDIN_FILENO, action); }
285 * Shortcut to change the action for standard output.
287 Options& stdout(int action) { return fd(STDOUT_FILENO, action); }
290 * Shortcut to change the action for standard error.
291 * Note that stderr(1) will redirect the standard error to the same
292 * file descriptor as standard output; the equivalent of bash's "2>&1"
294 Options& stderr(int action) { return fd(STDERR_FILENO, action); }
296 Options& pipeStdin() { return fd(STDIN_FILENO, PIPE_IN); }
297 Options& pipeStdout() { return fd(STDOUT_FILENO, PIPE_OUT); }
298 Options& pipeStderr() { return fd(STDERR_FILENO, PIPE_OUT); }
301 * Close all other fds (other than standard input, output, error,
302 * and file descriptors explicitly specified with fd()).
304 * This is potentially slow; it's generally a better idea to
305 * set the close-on-exec flag on all file descriptors that shouldn't
306 * be inherited by the child.
308 * Even with this option set, standard input, output, and error are
309 * not closed; use stdin(CLOSE), stdout(CLOSE), stderr(CLOSE) if you
312 Options& closeOtherFds() { closeOtherFds_ = true; return *this; }
315 * Use the search path ($PATH) when searching for the executable.
317 Options& usePath() { usePath_ = true; return *this; }
320 * Change the child's working directory, after the vfork.
322 Options& chdir(const std::string& dir) { childDir_ = dir; return *this; }
326 * Child will receive a signal when the parent exits.
328 Options& parentDeathSignal(int sig) {
329 parentDeathSignal_ = sig;
335 * Child will be made a process group leader when it starts. Upside: one
336 * can reliably all its kill non-daemonizing descendants. Downside: the
337 * child will not receive Ctrl-C etc during interactive use.
339 Options& processGroupLeader() {
340 processGroupLeader_ = true;
345 * Helpful way to combine Options.
347 Options& operator|=(const Options& other);
350 typedef boost::container::flat_map<int, int> FdMap;
352 bool closeOtherFds_{false};
353 bool usePath_{false};
354 std::string childDir_; // "" keeps the parent's working directory
356 int parentDeathSignal_{0};
358 bool processGroupLeader_{false};
361 static Options pipeStdin() { return Options().stdin(PIPE); }
362 static Options pipeStdout() { return Options().stdout(PIPE); }
363 static Options pipeStderr() { return Options().stderr(PIPE); }
365 // Non-copiable, but movable
366 Subprocess(const Subprocess&) = delete;
367 Subprocess& operator=(const Subprocess&) = delete;
368 Subprocess(Subprocess&&) = default;
369 Subprocess& operator=(Subprocess&&) = default;
372 * Create a subprocess from the given arguments. argv[0] must be listed.
373 * If not-null, executable must be the actual executable
374 * being used (otherwise it's the same as argv[0]).
376 * If env is not-null, it must contain name=value strings to be used
377 * as the child's environment; otherwise, we inherit the environment
378 * from the parent. env must be null if options.usePath is set.
381 const std::vector<std::string>& argv,
382 const Options& options = Options(),
383 const char* executable = nullptr,
384 const std::vector<std::string>* env = nullptr);
388 * Create a subprocess run as a shell command (as shell -c 'command')
390 * The shell to use is taken from the environment variable $SHELL,
391 * or /bin/sh if $SHELL is unset.
394 const std::string& cmd,
395 const Options& options = Options(),
396 const std::vector<std::string>* env = nullptr);
399 //// The methods below only manipulate the process state, and do not
400 //// affect its communication pipes.
404 * Return the child's pid, or -1 if the child wasn't successfully spawned
405 * or has already been wait()ed upon.
410 * Return the child's status (as per wait()) if the process has already
411 * been waited on, -1 if the process is still running, or -2 if the
412 * process hasn't been successfully started. NOTE that this does not call
413 * waitpid() or Subprocess::poll(), but simply returns the status stored
414 * in the Subprocess object.
416 ProcessReturnCode returnCode() const { return returnCode_; }
419 * Poll the child's status and return it. Return the exit status if the
420 * subprocess had quit, or RUNNING otherwise. Throws an std::logic_error
421 * if called on a Subprocess whose status is no longer RUNNING. No other
422 * exceptions are possible. Aborts on egregious violations of contract,
423 * e.g. if you wait for the underlying process without going through this
424 * Subprocess instance.
426 ProcessReturnCode poll();
429 * Poll the child's status. If the process is still running, return false.
430 * Otherwise, return true if the process exited with status 0 (success),
431 * or throw CalledProcessError if the process exited with a non-zero status.
436 * Wait for the process to terminate and return its status. Like poll(),
437 * the only exception this can throw is std::logic_error if you call this
438 * on a Subprocess whose status is RUNNING. Aborts on egregious
439 * violations of contract, like an out-of-band waitpid(p.pid(), 0, 0).
441 ProcessReturnCode wait();
444 * Wait for the process to terminate, throw if unsuccessful.
449 * Send a signal to the child. Shortcuts for the commonly used Unix
452 void sendSignal(int signal);
453 void terminate() { sendSignal(SIGTERM); }
454 void kill() { sendSignal(SIGKILL); }
457 //// The methods below only affect the process's communication pipes, but
458 //// not its return code or state (they do not poll() or wait()).
462 * Communicate with the child until all pipes to/from the child are closed.
464 * The input buffer is written to the process' stdin pipe, and data is read
465 * from the stdout and stderr pipes. Non-blocking I/O is performed on all
466 * pipes simultaneously to avoid deadlocks.
468 * The stdin pipe will be closed after the full input buffer has been written.
469 * An error will be thrown if a non-empty input buffer is supplied but stdin
470 * was not configured as a pipe.
472 * Returns a pair of buffers containing the data read from stdout and stderr.
473 * If stdout or stderr is not a pipe, an empty IOBuf queue will be returned
474 * for the respective buffer.
476 * Note that communicate() and communicateIOBuf() both return when all
477 * pipes to/from the child are closed; the child might stay alive after
478 * that, so you must still wait().
480 * communicateIOBuf() uses IOBufQueue for buffering (which has the
481 * advantage that it won't try to allocate all data at once), but it does
482 * store the subprocess's entire output in memory before returning.
484 * communicate() uses strings for simplicity.
486 std::pair<IOBufQueue, IOBufQueue> communicateIOBuf(
487 IOBufQueue input = IOBufQueue());
489 std::pair<std::string, std::string> communicate(
490 StringPiece input = StringPiece());
493 * Communicate with the child until all pipes to/from the child are closed.
497 * readCallback(pfd, cfd) will be called whenever there's data available
498 * on any pipe *from* the child (PIPE_OUT). pfd is the file descriptor
499 * in the parent (that you use to read from); cfd is the file descriptor
500 * in the child (used for identifying the stream; 1 = child's standard
501 * output, 2 = child's standard error, etc)
503 * writeCallback(pfd, cfd) will be called whenever a pipe *to* the child is
504 * writable (PIPE_IN). pfd is the file descriptor in the parent (that you
505 * use to write to); cfd is the file descriptor in the child (used for
506 * identifying the stream; 0 = child's standard input, etc)
508 * The read and write callbacks must read from / write to pfd and return
509 * false during normal operation. Return true to tell communicate() to
510 * close the pipe. For readCallback, this might send SIGPIPE to the
511 * child, or make its writes fail with EPIPE, so you should generally
512 * avoid returning true unless you've reached end-of-file.
514 * communicate() returns when all pipes to/from the child are closed; the
515 * child might stay alive after that, so you must still wait().
516 * Conversely, the child may quit long before its pipes are closed, since
517 * its descendants can keep them alive forever.
519 * Most users won't need to use this callback version; the simpler version
520 * of communicate (which buffers data in memory) will probably work fine.
522 * == Things you must get correct ==
524 * 1) You MUST consume all data passed to readCallback (or return true to
525 * close the pipe). Similarly, you MUST write to a writable pipe (or
526 * return true to close the pipe). To do otherwise is an error that can
527 * result in a deadlock. You must do this even for pipes you are not
530 * 2) pfd is nonblocking, so be prepared for read() / write() to return -1
531 * and set errno to EAGAIN (in which case you should return false). Use
532 * readNoInt() from FileUtil.h to handle interrupted reads for you.
534 * 3) Your callbacks MUST NOT call any of the Subprocess methods that
535 * manipulate the pipe FDs. Check the docblocks, but, for example,
536 * neither closeParentFd (return true instead) nor takeOwnershipOfPipes
537 * are safe. Stick to reading/writing from pfd, as appropriate.
541 * 1) See ReadLinesCallback for an easy way to consume the child's output
542 * streams line-by-line (or tokenized by another delimiter).
544 * 2) "Wait until the descendants close the pipes" is usually the behavior
545 * you want, since the descendants may have something to say even if the
546 * immediate child is dead. If you need to be able to force-close all
547 * parent FDs, communicate() will NOT work for you. Do it your own way by
548 * using takeOwnershipOfPipes().
550 * Why not? You can return "true" from your callbacks to sever active
551 * pipes, but inactive ones can remain open indefinitely. It is
552 * impossible to safely close inactive pipes while another thread is
553 * blocked in communicate(). This is BY DESIGN. Racing communicate()'s
554 * read/write callbacks can result in wrong I/O and data corruption. This
555 * class would need internal synchronization and timeouts, a poor and
556 * expensive implementation choice, in order to make closeParentFd()
559 typedef std::function<bool(int, int)> FdCallback;
560 void communicate(FdCallback readCallback, FdCallback writeCallback);
563 * A readCallback for Subprocess::communicate() that helps you consume
564 * lines (or other delimited pieces) from your subprocess's file
565 * descriptors. Use the readLinesCallback() helper to get template
566 * deduction. For example:
568 * auto read_cb = Subprocess::readLinesCallback(
569 * [](int fd, folly::StringPiece s) {
570 * std::cout << fd << " said: " << s;
571 * return false; // Keep reading from the child
574 * subprocess.communicate(
575 * // ReadLinesCallback contains StreamSplitter contains IOBuf, making
576 * // it noncopyable, whereas std::function must be copyable. So, we
577 * // keep the callback in a local, and instead pass a reference.
579 * [](int pdf, int cfd){ return true; } // Don't write to the child
582 * If a file line exceeds maxLineLength, your callback will get some
583 * initial chunks of maxLineLength with no trailing delimiters. The final
584 * chunk of a line is delimiter-terminated iff the delimiter was present
585 * in the input. In particular, the last line in a file always lacks a
586 * delimiter -- so if a file ends on a delimiter, the final line is empty.
588 * Like a regular communicate() callback, your fdLineCb() normally returns
589 * false. It may return true to tell Subprocess to close the underlying
590 * file descriptor. The child process may then receive SIGPIPE or get
591 * EPIPE errors on writes.
593 template <class Callback>
594 class ReadLinesCallback {
596 // Binds an FD to the client-provided FD+line callback
597 struct StreamSplitterCallback {
598 StreamSplitterCallback(Callback& cb, int fd) : cb_(cb), fd_(fd) { }
599 // The return value semantics are inverted vs StreamSplitter
600 bool operator()(StringPiece s) { return !cb_(fd_, s); }
604 typedef gen::StreamSplitter<StreamSplitterCallback> LineSplitter;
606 explicit ReadLinesCallback(
608 uint64_t maxLineLength = 0, // No line length limit by default
609 char delimiter = '\n',
610 uint64_t bufSize = 1024
611 ) : fdLineCb_(std::move(fdLineCb)),
612 maxLineLength_(maxLineLength),
613 delimiter_(delimiter),
616 bool operator()(int pfd, int cfd) {
617 // Make a splitter for this cfd if it doesn't already exist
618 auto it = fdToSplitter_.find(cfd);
619 auto& splitter = (it != fdToSplitter_.end()) ? it->second
620 : fdToSplitter_.emplace(cfd, LineSplitter(
621 delimiter_, StreamSplitterCallback(fdLineCb_, cfd), maxLineLength_
623 // Read as much as we can from this FD
626 ssize_t ret = readNoInt(pfd, buf, bufSize_);
627 if (ret == -1 && errno == EAGAIN) { // No more data for now
630 if (ret == 0) { // Reached end-of-file
631 splitter.flush(); // Ignore return since the file is over anyway
634 if (!splitter(StringPiece(buf, ret))) {
635 return true; // The callback told us to stop
642 const uint64_t maxLineLength_;
643 const char delimiter_;
644 const uint64_t bufSize_;
645 // We lazily make splitters for all cfds that get used.
646 std::unordered_map<int, LineSplitter> fdToSplitter_;
649 // Helper to enable template deduction
650 template <class Callback>
651 static ReadLinesCallback<Callback> readLinesCallback(
653 uint64_t maxLineLength = 0, // No line length limit by default
654 char delimiter = '\n',
655 uint64_t bufSize = 1024) {
656 return ReadLinesCallback<Callback>(
657 std::move(fdLineCb), maxLineLength, delimiter, bufSize
662 * communicate() callbacks can use this to temporarily enable/disable
663 * notifications (callbacks) for a pipe to/from the child. By default,
664 * all are enabled. Useful for "chatty" communication -- you want to
665 * disable write callbacks until you receive the expected message.
667 * Disabling a pipe does not free you from the requirement to consume all
668 * incoming data. Failing to do so will easily create deadlock bugs.
670 * Throws if the childFd is not known.
672 void enableNotifications(int childFd, bool enabled);
675 * Are notifications for one pipe to/from child enabled? Throws if the
676 * childFd is not known.
678 bool notificationsEnabled(int childFd) const;
681 //// The following methods are meant for the cases when communicate() is
682 //// not suitable. You should not need them when you call communicate(),
683 //// and, in fact, it is INHERENTLY UNSAFE to use closeParentFd() or
684 //// takeOwnershipOfPipes() from a communicate() callback.
688 * Close the parent file descriptor given a file descriptor in the child.
689 * DO NOT USE from communicate() callbacks; make them return true instead.
691 void closeParentFd(int childFd);
694 * Set all pipes from / to child to be non-blocking. communicate() does
697 void setAllNonBlocking();
700 * Get parent file descriptor corresponding to the given file descriptor
701 * in the child. Throws if childFd isn't a pipe (PIPE_IN / PIPE_OUT).
702 * Do not close() the returned file descriptor; use closeParentFd, above.
704 int parentFd(int childFd) const {
705 return pipes_[findByChildFd(childFd)].pipe.fd();
707 int stdin() const { return parentFd(0); }
708 int stdout() const { return parentFd(1); }
709 int stderr() const { return parentFd(2); }
712 * The child's pipes are logically separate from the process metadata
713 * (they may even be kept alive by the child's descendants). This call
714 * lets you manage the pipes' lifetime separetely from the lifetime of the
717 * After this call, the Subprocess instance will have no knowledge of
718 * these pipes, and the caller assumes responsibility for managing their
719 * lifetimes. Pro-tip: prefer to explicitly close() the pipes, since
720 * folly::File would otherwise silently suppress I/O errors.
722 * No, you may NOT call this from a communicate() callback.
725 ChildPipe(int fd, folly::File&& ppe) : childFd(fd), pipe(std::move(ppe)) {}
727 folly::File pipe; // Owns the parent FD
729 std::vector<ChildPipe> takeOwnershipOfPipes();
732 static const int RV_RUNNING = ProcessReturnCode::RV_RUNNING;
733 static const int RV_NOT_STARTED = ProcessReturnCode::RV_NOT_STARTED;
735 // spawn() sets up a pipe to read errors from the child,
736 // then calls spawnInternal() to do the bulk of the work. Once
737 // spawnInternal() returns it reads the error pipe to see if the child
738 // encountered any errors.
740 std::unique_ptr<const char*[]> argv,
741 const char* executable,
742 const Options& options,
743 const std::vector<std::string>* env);
745 std::unique_ptr<const char*[]> argv,
746 const char* executable,
748 const std::vector<std::string>* env,
751 // Actions to run in child.
752 // Note that this runs after vfork(), so tread lightly.
753 // Returns 0 on success, or an errno value on failure.
754 int prepareChild(const Options& options,
755 const sigset_t* sigmask,
756 const char* childDir) const;
757 int runChild(const char* executable, char** argv, char** env,
758 const Options& options) const;
761 * Read from the error pipe, and throw SubprocessSpawnError if the child
762 * failed before calling exec().
764 void readChildErrorPipe(int pfd, const char* executable);
766 // Returns an index into pipes_. Throws std::invalid_argument if not found.
767 size_t findByChildFd(const int childFd) const;
771 ProcessReturnCode returnCode_;
774 * Represents a pipe between this process, and the child process (or its
775 * descendant). To interact with these pipes, you can use communicate(),
776 * or use parentFd() and related methods, or separate them from the
777 * Subprocess instance entirely via takeOwnershipOfPipes().
779 struct Pipe : private boost::totally_ordered<Pipe> {
780 folly::File pipe; // Our end of the pipe, wrapped in a File to auto-close.
781 int childFd = -1; // Identifies the pipe: what FD is this in the child?
782 int direction = PIPE_IN; // one of PIPE_IN / PIPE_OUT
783 bool enabled = true; // Are notifications enabled in communicate()?
785 bool operator<(const Pipe& other) const {
786 return childFd < other.childFd;
788 bool operator==(const Pipe& other) const {
789 return childFd == other.childFd;
793 // Populated at process start according to fdActions, empty after
794 // takeOwnershipOfPipes(). Sorted by childFd. Can only have elements
795 // erased, but not inserted, after being populated.
797 // The number of pipes between parent and child is assumed to be small,
798 // so we're happy with a vector here, even if it means linear erase.
799 std::vector<Pipe> pipes_;
802 inline Subprocess::Options& Subprocess::Options::operator|=(
803 const Subprocess::Options& other) {
804 if (this == &other) return *this;
806 for (auto& p : other.fdActions_) {
807 fdActions_[p.first] = p.second;
809 closeOtherFds_ |= other.closeOtherFds_;
810 usePath_ |= other.usePath_;
811 processGroupLeader_ |= other.processGroupLeader_;
817 #endif /* FOLLY_SUBPROCESS_H_ */