2 * Copyright 2013 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.
17 #include "folly/Subprocess.h"
26 #include <system_error>
28 #include <boost/container/flat_set.hpp>
29 #include <boost/range/adaptors.hpp>
31 #include <glog/logging.h>
33 #include "folly/Conv.h"
34 #include "folly/ScopeGuard.h"
35 #include "folly/String.h"
36 #include "folly/io/Cursor.h"
38 extern char** environ;
42 ProcessReturnCode::State ProcessReturnCode::state() const {
43 if (rawStatus_ == RV_NOT_STARTED) return NOT_STARTED;
44 if (rawStatus_ == RV_RUNNING) return RUNNING;
45 if (WIFEXITED(rawStatus_)) return EXITED;
46 if (WIFSIGNALED(rawStatus_)) return KILLED;
47 throw std::runtime_error(to<std::string>(
48 "Invalid ProcessReturnCode: ", rawStatus_));
51 void ProcessReturnCode::enforce(State s) const {
53 throw std::logic_error(to<std::string>("Invalid state ", s));
57 int ProcessReturnCode::exitStatus() const {
59 return WEXITSTATUS(rawStatus_);
62 int ProcessReturnCode::killSignal() const {
64 return WTERMSIG(rawStatus_);
67 bool ProcessReturnCode::coreDumped() const {
69 return WCOREDUMP(rawStatus_);
72 std::string ProcessReturnCode::str() const {
79 return to<std::string>("exited with status ", exitStatus());
81 return to<std::string>("killed by signal ", killSignal(),
82 (coreDumped() ? " (core dumped)" : ""));
84 CHECK(false); // unreached
87 CalledProcessError::CalledProcessError(ProcessReturnCode rc)
89 what_(returnCode_.str()) {
94 // Copy pointers to the given strings in a format suitable for posix_spawn
95 std::unique_ptr<const char*[]> cloneStrings(const std::vector<std::string>& s) {
96 std::unique_ptr<const char*[]> d(new const char*[s.size() + 1]);
97 for (int i = 0; i < s.size(); i++) {
100 d[s.size()] = nullptr;
104 // Helper to throw std::system_error
105 void throwSystemError(int err, const char* msg) __attribute__((noreturn));
106 void throwSystemError(int err, const char* msg) {
107 throw std::system_error(err, std::system_category(), msg);
110 // Helper to throw std::system_error from errno
111 void throwSystemError(const char* msg) __attribute__((noreturn));
112 void throwSystemError(const char* msg) {
113 throwSystemError(errno, msg);
116 // Check a Posix return code (0 on success, error number on error), throw
118 void checkPosixError(int err, const char* msg) {
120 throwSystemError(err, msg);
124 // Check a traditional Uinx return code (-1 and sets errno on error), throw
126 void checkUnixError(ssize_t ret, const char* msg) {
128 throwSystemError(msg);
131 void checkUnixError(ssize_t ret, int savedErrno, const char* msg) {
133 throwSystemError(savedErrno, msg);
137 // Check a wait() status, throw on non-successful
138 void checkStatus(ProcessReturnCode returnCode) {
139 if (returnCode.state() != ProcessReturnCode::EXITED ||
140 returnCode.exitStatus() != 0) {
141 throw CalledProcessError(returnCode);
147 Subprocess::Options& Subprocess::Options::fd(int fd, int action) {
148 if (action == Subprocess::PIPE) {
150 action = Subprocess::PIPE_IN;
151 } else if (fd == 1 || fd == 2) {
152 action = Subprocess::PIPE_OUT;
154 throw std::invalid_argument(
155 to<std::string>("Only fds 0, 1, 2 are valid for action=PIPE: ", fd));
158 fdActions_[fd] = action;
162 Subprocess::Subprocess(
163 const std::vector<std::string>& argv,
164 const Options& options,
165 const char* executable,
166 const std::vector<std::string>* env)
168 returnCode_(RV_NOT_STARTED) {
170 throw std::invalid_argument("argv must not be empty");
172 if (!executable) executable = argv[0].c_str();
173 spawn(cloneStrings(argv), executable, options, env);
176 Subprocess::Subprocess(
177 const std::string& cmd,
178 const Options& options,
179 const std::vector<std::string>* env)
181 returnCode_(RV_NOT_STARTED) {
182 if (options.usePath_) {
183 throw std::invalid_argument("usePath() not allowed when running in shell");
185 const char* shell = getenv("SHELL");
190 std::unique_ptr<const char*[]> argv(new const char*[4]);
193 argv[2] = cmd.c_str();
195 spawn(std::move(argv), shell, options, env);
198 Subprocess::~Subprocess() {
199 CHECK_NE(returnCode_.state(), ProcessReturnCode::RUNNING)
200 << "Subprocess destroyed without reaping child";
204 void closeChecked(int fd) {
205 checkUnixError(::close(fd), "close");
209 void Subprocess::closeAll() {
210 for (auto& p : pipes_) {
211 closeChecked(p.parentFd);
216 void Subprocess::setAllNonBlocking() {
217 for (auto& p : pipes_) {
219 int flags = ::fcntl(fd, F_GETFL);
220 checkUnixError(flags, "fcntl");
221 int r = ::fcntl(fd, F_SETFL, flags | O_NONBLOCK);
222 checkUnixError(r, "fcntl");
226 void Subprocess::spawn(
227 std::unique_ptr<const char*[]> argv,
228 const char* executable,
229 const Options& optionsIn,
230 const std::vector<std::string>* env) {
231 if (optionsIn.usePath_ && env) {
232 throw std::invalid_argument(
233 "usePath() not allowed when overriding environment");
236 // Make a copy, we'll mutate options
237 Options options(optionsIn);
239 // Parent work, pre-fork: create pipes
240 std::vector<int> childFds;
241 for (auto& p : options.fdActions_) {
242 if (p.second == PIPE_IN || p.second == PIPE_OUT) {
245 checkUnixError(r, "pipe");
247 pinfo.direction = p.second;
249 if (p.second == PIPE_IN) {
250 // Child gets reading end
251 pinfo.parentFd = fds[1];
254 pinfo.parentFd = fds[0];
257 p.second = cfd; // ensure it gets dup2()ed
258 pinfo.childFd = p.first;
259 childFds.push_back(cfd);
260 pipes_.push_back(pinfo);
264 // This should already be sorted, as options.fdActions_ is
265 DCHECK(std::is_sorted(pipes_.begin(), pipes_.end()));
267 // Note that the const casts below are legit, per
268 // http://pubs.opengroup.org/onlinepubs/009695399/functions/exec.html
270 char** argVec = const_cast<char**>(argv.get());
272 // Set up environment
273 std::unique_ptr<const char*[]> envHolder;
276 envHolder = cloneStrings(*env);
277 envVec = const_cast<char**>(envHolder.get());
282 // Block all signals around vfork; see http://ewontfix.com/7/.
284 // As the child may run in the same address space as the parent until
285 // the actual execve() system call, any (custom) signal handlers that
286 // the parent has might alter parent's memory if invoked in the child,
287 // with undefined results. So we block all signals in the parent before
288 // vfork(), which will cause them to be blocked in the child as well (we
289 // rely on the fact that Linux, just like all sane implementations, only
290 // clones the calling thread). Then, in the child, we reset all signals
291 // to their default dispositions (while still blocked), and unblock them
292 // (so the exec()ed process inherits the parent's signal mask)
294 // The parent also unblocks all signals as soon as vfork() returns.
296 int r = ::sigfillset(&allBlocked);
297 checkUnixError(r, "sigfillset");
299 r = pthread_sigmask(SIG_SETMASK, &allBlocked, &oldSignals);
300 checkPosixError(r, "pthread_sigmask");
304 // While all signals are blocked, we must reset their
305 // dispositions to default.
306 for (int sig = 1; sig < NSIG; ++sig) {
307 ::signal(sig, SIG_DFL);
309 // Unblock signals; restore signal mask.
310 int r = pthread_sigmask(SIG_SETMASK, &oldSignals, nullptr);
313 runChild(executable, argVec, envVec, options);
314 // This should never return, but there's nothing else we can do here.
317 // In parent. We want to restore the signal mask even if vfork fails,
318 // so we'll save errno here, restore the signal mask, and only then
320 int savedErrno = errno;
322 // Restore signal mask; do this even if vfork fails!
323 // We only check for errors from pthread_sigmask after we recorded state
324 // that the child is alive, so we know to reap it.
325 r = pthread_sigmask(SIG_SETMASK, &oldSignals, nullptr);
326 checkUnixError(pid, savedErrno, "vfork");
330 returnCode_ = ProcessReturnCode(RV_RUNNING);
332 // Parent work, post-fork: close child's ends of pipes
333 for (int f : childFds) {
337 checkPosixError(r, "pthread_sigmask");
342 // Checked version of close() to use in the child: abort() on error
343 void childClose(int fd) {
345 if (r == -1) abort();
348 // Checked version of dup2() to use in the child: abort() on error
349 void childDup2(int oldfd, int newfd) {
350 int r = ::dup2(oldfd, newfd);
351 if (r == -1) abort();
356 void Subprocess::runChild(const char* executable,
357 char** argv, char** env,
358 const Options& options) const {
359 // Close parent's ends of all pipes
360 for (auto& p : pipes_) {
361 childClose(p.parentFd);
364 // Close all fds that we're supposed to close.
365 // Note that we're ignoring errors here, in case some of these
366 // fds were set to close on exec.
367 for (auto& p : options.fdActions_) {
368 if (p.second == CLOSE) {
371 childDup2(p.second, p.first);
375 // If requested, close all other file descriptors. Don't close
376 // any fds in options.fdActions_, and don't touch stdin, stdout, stderr.
378 if (options.closeOtherFds_) {
379 for (int fd = getdtablesize() - 1; fd >= 3; --fd) {
380 if (options.fdActions_.count(fd) == 0) {
386 // Now, finally, exec.
388 if (options.usePath_) {
389 ::execvp(executable, argv);
391 ::execve(executable, argv, env);
394 // If we're here, something's wrong.
398 ProcessReturnCode Subprocess::poll() {
399 returnCode_.enforce(ProcessReturnCode::RUNNING);
402 pid_t found = ::waitpid(pid_, &status, WNOHANG);
403 checkUnixError(found, "waitpid");
405 returnCode_ = ProcessReturnCode(status);
411 bool Subprocess::pollChecked() {
412 if (poll().state() == ProcessReturnCode::RUNNING) {
415 checkStatus(returnCode_);
419 ProcessReturnCode Subprocess::wait() {
420 returnCode_.enforce(ProcessReturnCode::RUNNING);
425 found = ::waitpid(pid_, &status, 0);
426 } while (found == -1 && errno == EINTR);
427 checkUnixError(found, "waitpid");
428 DCHECK_EQ(found, pid_);
429 returnCode_ = ProcessReturnCode(status);
433 void Subprocess::waitChecked() {
435 checkStatus(returnCode_);
438 void Subprocess::sendSignal(int signal) {
439 returnCode_.enforce(ProcessReturnCode::RUNNING);
440 int r = ::kill(pid_, signal);
441 checkUnixError(r, "kill");
446 std::pair<const uint8_t*, size_t> queueFront(const IOBufQueue& queue) {
447 auto* p = queue.front();
448 if (!p) return std::make_pair(nullptr, 0);
449 return io::Cursor(p).peek();
453 bool handleWrite(int fd, IOBufQueue& queue) {
455 auto p = queueFront(queue);
462 n = ::write(fd, p.first, p.second);
463 } while (n == -1 && errno == EINTR);
464 if (n == -1 && errno == EAGAIN) {
467 checkUnixError(n, "write");
473 bool handleRead(int fd, IOBufQueue& queue) {
475 auto p = queue.preallocate(100, 65000);
478 n = ::read(fd, p.first, p.second);
479 } while (n == -1 && errno == EINTR);
480 if (n == -1 && errno == EAGAIN) {
483 checkUnixError(n, "read");
487 queue.postallocate(n);
491 bool discardRead(int fd) {
492 static const size_t bufSize = 65000;
493 // Thread unsafe, but it doesn't matter.
494 static std::unique_ptr<char[]> buf(new char[bufSize]);
499 n = ::read(fd, buf.get(), bufSize);
500 } while (n == -1 && errno == EINTR);
501 if (n == -1 && errno == EAGAIN) {
504 checkUnixError(n, "read");
513 std::pair<std::string, std::string> Subprocess::communicate(
514 const CommunicateFlags& flags,
516 IOBufQueue dataQueue;
517 dataQueue.wrapBuffer(data.data(), data.size());
519 auto outQueues = communicateIOBuf(flags, std::move(dataQueue));
520 auto outBufs = std::make_pair(outQueues.first.move(),
521 outQueues.second.move());
522 std::pair<std::string, std::string> out;
524 outBufs.first->coalesce();
525 out.first.assign(reinterpret_cast<const char*>(outBufs.first->data()),
526 outBufs.first->length());
528 if (outBufs.second) {
529 outBufs.second->coalesce();
530 out.second.assign(reinterpret_cast<const char*>(outBufs.second->data()),
531 outBufs.second->length());
536 std::pair<IOBufQueue, IOBufQueue> Subprocess::communicateIOBuf(
537 const CommunicateFlags& flags,
539 std::pair<IOBufQueue, IOBufQueue> out;
541 auto readCallback = [&] (int pfd, int cfd) -> bool {
542 if (cfd == 1 && flags.readStdout_) {
543 return handleRead(pfd, out.first);
544 } else if (cfd == 2 && flags.readStderr_) {
545 return handleRead(pfd, out.second);
547 // Don't close the file descriptor, the child might not like SIGPIPE,
548 // just read and throw the data away.
549 return discardRead(pfd);
553 auto writeCallback = [&] (int pfd, int cfd) -> bool {
554 if (cfd == 0 && flags.writeStdin_) {
555 return handleWrite(pfd, data);
557 // If we don't want to write to this fd, just close it.
562 communicate(std::move(readCallback), std::move(writeCallback));
567 void Subprocess::communicate(FdCallback readCallback,
568 FdCallback writeCallback) {
569 returnCode_.enforce(ProcessReturnCode::RUNNING);
572 std::vector<pollfd> fds;
573 fds.reserve(pipes_.size());
574 std::vector<int> toClose;
575 toClose.reserve(pipes_.size());
577 while (!pipes_.empty()) {
581 for (auto& p : pipes_) {
584 // Yes, backwards, PIPE_IN / PIPE_OUT are defined from the
585 // child's point of view.
586 pfd.events = (p.direction == PIPE_IN ? POLLOUT : POLLIN);
592 r = ::poll(fds.data(), fds.size(), -1);
593 } while (r == -1 && errno == EINTR);
594 checkUnixError(r, "poll");
596 for (int i = 0; i < pipes_.size(); ++i) {
598 DCHECK_EQ(fds[i].fd, p.parentFd);
599 short events = fds[i].revents;
602 if (events & POLLOUT) {
603 DCHECK(!(events & POLLIN));
604 if (writeCallback(p.parentFd, p.childFd)) {
605 toClose.push_back(i);
610 if (events & POLLIN) {
611 DCHECK(!(events & POLLOUT));
612 if (readCallback(p.parentFd, p.childFd)) {
613 toClose.push_back(i);
618 if ((events & (POLLHUP | POLLERR)) && !closed) {
619 toClose.push_back(i);
624 // Close the fds in reverse order so the indexes hold after erase()
625 for (int idx : boost::adaptors::reverse(toClose)) {
626 auto pos = pipes_.begin() + idx;
627 closeChecked(pos->parentFd);
633 int Subprocess::findByChildFd(int childFd) const {
634 auto pos = std::lower_bound(
635 pipes_.begin(), pipes_.end(), childFd,
636 [] (const PipeInfo& info, int fd) { return info.childFd < fd; });
637 if (pos == pipes_.end() || pos->childFd != childFd) {
638 throw std::invalid_argument(folly::to<std::string>(
639 "child fd not found ", childFd));
641 return pos - pipes_.begin();
644 void Subprocess::closeParentFd(int childFd) {
645 int idx = findByChildFd(childFd);
646 closeChecked(pipes_[idx].parentFd);
647 pipes_.erase(pipes_.begin() + idx);
655 // We like EPIPE, thanks.
656 ::signal(SIGPIPE, SIG_IGN);
660 Initializer initializer;