binder: Add execute() to host utils.
Add utility for executing commands.
This function assumes that, when a given predicate
|end| finishes, the child process does not emit any other
messages.
If this is not the case, caller to execute()
must handle these I/O in the pipes in the returned
CommandResult object. Otherwise the child program may
hang on I/O.
Test: binderUtilsTest
Bug: 190233850
Change-Id: Ib8be5db140af04a286ccbb2283cb032390aff5ac
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index b9c8d20..467b0e6 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -146,6 +146,14 @@
darwin: {
enabled: false,
},
+ host: {
+ static_libs: [
+ "libbase",
+ ],
+ srcs: [
+ "UtilsHost.cpp",
+ ],
+ },
},
aidl: {
diff --git a/libs/binder/TEST_MAPPING b/libs/binder/TEST_MAPPING
index b58d919..59f0ba6 100644
--- a/libs/binder/TEST_MAPPING
+++ b/libs/binder/TEST_MAPPING
@@ -31,6 +31,9 @@
"name": "binderStabilityTest"
},
{
+ "name": "binderUtilsTest"
+ },
+ {
"name": "libbinder_ndk_unit_test"
},
{
diff --git a/libs/binder/UtilsHost.cpp b/libs/binder/UtilsHost.cpp
new file mode 100644
index 0000000..e524dab
--- /dev/null
+++ b/libs/binder/UtilsHost.cpp
@@ -0,0 +1,177 @@
+/*
+ * 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.stdout << ", stderr=" << res.stderr;
+}
+
+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.stdout))
+ return android::base::ErrnoError() << "read(stdout)";
+ if (!handlePoll(&ret.errPipe, *errPollFd, &ret.stderr))
+ 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
diff --git a/libs/binder/UtilsHost.h b/libs/binder/UtilsHost.h
new file mode 100644
index 0000000..0f29f60
--- /dev/null
+++ b/libs/binder/UtilsHost.h
@@ -0,0 +1,99 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <optional>
+#include <ostream>
+#include <string>
+#include <variant>
+#include <vector>
+
+#include <android-base/macros.h>
+#include <android-base/result.h>
+#include <android-base/unique_fd.h>
+
+/**
+ * Log a lot more information about host-device binder communication, when debugging issues.
+ */
+#define SHOULD_LOG_HOST false
+
+#if SHOULD_LOG_HOST
+#define LOG_HOST(...) ALOGI(__VA_ARGS__)
+#else
+#define LOG_HOST(...) ALOGV(__VA_ARGS__) // for type checking
+#endif
+
+namespace android {
+
+struct CommandResult {
+ std::optional<int32_t> exitCode;
+ std::optional<int32_t> signal;
+ std::optional<pid_t> pid;
+ std::string stdout;
+ std::string stderr;
+
+ android::base::unique_fd outPipe;
+ android::base::unique_fd errPipe;
+
+ CommandResult() = default;
+ CommandResult(CommandResult&& other) noexcept { (*this) = std::move(other); }
+ CommandResult& operator=(CommandResult&& other) noexcept {
+ std::swap(exitCode, other.exitCode);
+ std::swap(signal, other.signal);
+ std::swap(pid, other.pid);
+ std::swap(stdout, other.stdout);
+ std::swap(stderr, other.stderr);
+ return *this;
+ }
+ ~CommandResult();
+ [[nodiscard]] std::string toString() const;
+
+ [[nodiscard]] bool stdoutEndsWithNewLine() const {
+ return !stdout.empty() && stdout.back() == '\n';
+ }
+
+private:
+ DISALLOW_COPY_AND_ASSIGN(CommandResult);
+};
+
+std::ostream& operator<<(std::ostream& os, const CommandResult& res);
+
+// Execute a command using tokens specified in @a argStringVec.
+//
+// @a end is a predicate checked periodically when the command emits any output to stdout or
+// stderr. When it is evaluated to true, the function returns immediately even though
+// the child process has not been terminated. The function also assumes that, after @a end
+// is evaluated to true, the child process does not emit any other messages.
+// If this is not the case, caller to execute() must handle these I/O in the pipes in the returned
+// CommandResult object. Otherwise the child program may hang on I/O.
+//
+// If @a end is nullptr, it is equivalent to a predicate that always returns false. In this
+// case, execute() returns after the child process is terminated.
+//
+// If @a end is evaluated to true, and execute() returns with the child process running,
+// the returned CommandResult has pid, outPipe, and errPipe set. In this case, the caller is
+// responsible for holding the returned CommandResult. When the CommandResult object is destroyed,
+// the child process is killed.
+//
+// On the other hand, execute() returns with the child process terminated, either exitCode or signal
+// is set.
+//
+// If the parent process has encountered any errors for system calls, return ExecuteError with
+// the proper errno set.
+android::base::Result<CommandResult> execute(std::vector<std::string> argStringVec,
+ const std::function<bool(const CommandResult&)>& end);
+} // namespace android
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index c7c899f..0aa3139 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -327,3 +327,17 @@
"libutils",
],
}
+
+cc_test_host {
+ name: "binderUtilsHostTest",
+ defaults: ["binder_test_defaults"],
+ srcs: ["binderUtilsHostTest.cpp"],
+ shared_libs: [
+ "libbase",
+ "libbinder",
+ ],
+ static_libs: [
+ "libgmock",
+ ],
+ test_suites: ["general-tests"],
+}
diff --git a/libs/binder/tests/binderUtilsHostTest.cpp b/libs/binder/tests/binderUtilsHostTest.cpp
new file mode 100644
index 0000000..fb24836
--- /dev/null
+++ b/libs/binder/tests/binderUtilsHostTest.cpp
@@ -0,0 +1,108 @@
+/*
+ * 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 <sysexits.h>
+
+#include <chrono>
+
+#include <android-base/result-gmock.h>
+#include <android-base/strings.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "../UtilsHost.h"
+
+using android::base::testing::Ok;
+using testing::Optional;
+
+namespace android {
+
+TEST(UtilsHost, ExecuteImmediately) {
+ auto result = execute({"echo", "foo"}, nullptr);
+ ASSERT_THAT(result, Ok());
+ EXPECT_THAT(result->exitCode, Optional(EX_OK));
+ EXPECT_EQ(result->stdout, "foo\n");
+}
+
+TEST(UtilsHost, ExecuteLongRunning) {
+ auto now = std::chrono::system_clock::now();
+
+ {
+ std::vector<std::string> args{"sh", "-c",
+ "sleep 0.5 && echo -n f && sleep 0.5 && echo oo && sleep 1"};
+ auto result = execute(std::move(args), [](const CommandResult& commandResult) {
+ return android::base::EndsWith(commandResult.stdout, "\n");
+ });
+ auto elapsed = std::chrono::system_clock::now() - now;
+ auto elapsedMs = std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count();
+ EXPECT_GE(elapsedMs, 1000);
+ EXPECT_LT(elapsedMs, 2000);
+
+ ASSERT_THAT(result, Ok());
+ EXPECT_EQ(std::nullopt, result->exitCode);
+ EXPECT_EQ(result->stdout, "foo\n");
+ }
+
+ // ~CommandResult() called, child process is killed.
+ // Assert that the second sleep does not finish.
+ auto elapsed = std::chrono::system_clock::now() - now;
+ auto elapsedMs = std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count();
+ EXPECT_LT(elapsedMs, 2000);
+}
+
+TEST(UtilsHost, ExecuteLongRunning2) {
+ auto now = std::chrono::system_clock::now();
+
+ {
+ std::vector<std::string> args{"sh", "-c",
+ "sleep 2 && echo -n f && sleep 2 && echo oo && sleep 2"};
+ auto result = execute(std::move(args), [](const CommandResult& commandResult) {
+ return android::base::EndsWith(commandResult.stdout, "\n");
+ });
+ auto elapsed = std::chrono::system_clock::now() - now;
+ auto elapsedMs = std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count();
+ EXPECT_GE(elapsedMs, 4000);
+ EXPECT_LT(elapsedMs, 6000);
+
+ ASSERT_THAT(result, Ok());
+ EXPECT_EQ(std::nullopt, result->exitCode);
+ EXPECT_EQ(result->stdout, "foo\n");
+ }
+
+ // ~CommandResult() called, child process is killed.
+ // Assert that the second sleep does not finish.
+ auto elapsed = std::chrono::system_clock::now() - now;
+ auto elapsedMs = std::chrono::duration_cast<std::chrono::milliseconds>(elapsed).count();
+ EXPECT_LT(elapsedMs, 6000);
+}
+
+TEST(UtilsHost, KillWithSigKill) {
+ std::vector<std::string> args{"sh", "-c", "echo foo && sleep 10"};
+ auto result = execute(std::move(args), [](const CommandResult& commandResult) {
+ // FOR TEST PURPOSE ONLY. DON'T DO THIS!
+ if (commandResult.pid.has_value()) {
+ (void)kill(*commandResult.pid, SIGKILL);
+ }
+ // FOR TEST PURPOSE ONLY. DON'T DO THIS!
+ return false;
+ });
+
+ ASSERT_THAT(result, Ok());
+ EXPECT_EQ(std::nullopt, result->exitCode);
+ EXPECT_THAT(result->signal, Optional(SIGKILL));
+}
+
+} // namespace android