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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "UtilsHost.h"
#include <poll.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sstream>
#include <log/log.h>
namespace android {
CommandResult::~CommandResult() {
if (!pid.has_value()) return;
if (*pid == 0) {
ALOGW("%s: PID is unexpectedly 0, won't kill it", __PRETTY_FUNCTION__);
return;
}
ALOGE_IF(kill(*pid, SIGKILL) != 0, "kill(%d): %s", *pid, strerror(errno));
while (pid.has_value()) {
int status;
LOG_HOST("%s: Waiting for PID %d to exit.", __PRETTY_FUNCTION__, *pid);
int waitres = waitpid(*pid, &status, 0);
if (waitres == -1) {
ALOGE("%s: waitpid(%d): %s", __PRETTY_FUNCTION__, *pid, strerror(errno));
break;
}
if (WIFEXITED(status)) {
LOG_HOST("%s: PID %d exited.", __PRETTY_FUNCTION__, *pid);
pid.reset();
} else if (WIFSIGNALED(status)) {
LOG_HOST("%s: PID %d terminated by signal %d.", __PRETTY_FUNCTION__, *pid,
WTERMSIG(status));
pid.reset();
} else if (WIFSTOPPED(status)) {
ALOGW("%s: pid %d stopped", __PRETTY_FUNCTION__, *pid);
} else if (WIFCONTINUED(status)) {
ALOGW("%s: pid %d continued", __PRETTY_FUNCTION__, *pid);
}
}
}
std::ostream& operator<<(std::ostream& os, const CommandResult& res) {
if (res.exitCode) os << "code=" << *res.exitCode;
if (res.signal) os << "signal=" << *res.signal;
if (res.pid) os << ", pid=" << *res.pid;
return os << ", stdout=" << res.stdoutStr << ", stderr=" << res.stderrStr;
}
std::string CommandResult::toString() const {
std::stringstream ss;
ss << (*this);
return ss.str();
}
android::base::Result<CommandResult> execute(std::vector<std::string> argStringVec,
const std::function<bool(const CommandResult&)>& end) {
// turn vector<string> into null-terminated char* vector.
std::vector<char*> argv;
argv.reserve(argStringVec.size() + 1);
for (auto& arg : argStringVec) argv.push_back(arg.data());
argv.push_back(nullptr);
CommandResult ret;
android::base::unique_fd outWrite;
if (!android::base::Pipe(&ret.outPipe, &outWrite))
return android::base::ErrnoError() << "pipe() for outPipe";
android::base::unique_fd errWrite;
if (!android::base::Pipe(&ret.errPipe, &errWrite))
return android::base::ErrnoError() << "pipe() for errPipe";
int pid = fork();
if (pid == -1) return android::base::ErrnoError() << "fork()";
if (pid == 0) {
// child
ret.outPipe.reset();
ret.errPipe.reset();
int res = TEMP_FAILURE_RETRY(dup2(outWrite.get(), STDOUT_FILENO));
LOG_ALWAYS_FATAL_IF(-1 == res, "dup2(outPipe): %s", strerror(errno));
outWrite.reset();
res = TEMP_FAILURE_RETRY(dup2(errWrite.get(), STDERR_FILENO));
LOG_ALWAYS_FATAL_IF(-1 == res, "dup2(errPipe): %s", strerror(errno));
errWrite.reset();
execvp(argv[0], argv.data());
LOG_ALWAYS_FATAL("execvp() returns");
}
// parent
outWrite.reset();
errWrite.reset();
ret.pid = pid;
auto handlePoll = [](android::base::unique_fd* fd, const pollfd* pfd, std::string* s) {
if (!fd->ok()) return true;
if (pfd->revents & POLLIN) {
char buf[1024];
ssize_t n = TEMP_FAILURE_RETRY(read(fd->get(), buf, sizeof(buf)));
if (n < 0) return false;
if (n > 0) *s += std::string_view(buf, n);
}
if (pfd->revents & POLLHUP) {
fd->reset();
}
return true;
};
// Drain both stdout and stderr. Check end() regularly until both are closed.
while (ret.outPipe.ok() || ret.errPipe.ok()) {
pollfd fds[2];
pollfd *outPollFd = nullptr, *errPollFd = nullptr;
memset(fds, 0, sizeof(fds));
nfds_t nfds = 0;
if (ret.outPipe.ok()) {
outPollFd = &fds[nfds++];
*outPollFd = {.fd = ret.outPipe.get(), .events = POLLIN};
}
if (ret.errPipe.ok()) {
errPollFd = &fds[nfds++];
*errPollFd = {.fd = ret.errPipe.get(), .events = POLLIN};
}
int pollRet = poll(fds, nfds, 1000 /* ms timeout */);
if (pollRet == -1) return android::base::ErrnoError() << "poll()";
if (!handlePoll(&ret.outPipe, outPollFd, &ret.stdoutStr))
return android::base::ErrnoError() << "read(stdout)";
if (!handlePoll(&ret.errPipe, errPollFd, &ret.stderrStr))
return android::base::ErrnoError() << "read(stderr)";
if (end && end(ret)) return ret;
}
// If both stdout and stderr are closed by the subprocess, it may or may not be terminated.
while (ret.pid.has_value()) {
int status;
auto exitPid = waitpid(pid, &status, 0);
if (exitPid == -1) return android::base::ErrnoError() << "waitpid(" << pid << ")";
if (exitPid == pid) {
if (WIFEXITED(status)) {
ret.pid = std::nullopt;
ret.exitCode = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
ret.pid = std::nullopt;
ret.signal = WTERMSIG(status);
} else if (WIFSTOPPED(status)) {
ALOGW("%s: pid %d stopped", __PRETTY_FUNCTION__, *ret.pid);
} else if (WIFCONTINUED(status)) {
ALOGW("%s: pid %d continued", __PRETTY_FUNCTION__, *ret.pid);
}
}
// ret is not changed unless the process is terminated (where pid == nullopt). Hence there
// is no need to check the predicate `end(ret)`.
}
return ret;
}
} // namespace android
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