init: Introduce class InterprocessFifo
Prepare for introducing a second interprocess communication channel by
introducing the class InterprocessFifo. Stop using std::unique_ptr<> for
holding the pipe file descriptors. Handle EOF consistently.
Bug: 213617178
Change-Id: Ic0cf18d3d8ea61b8ee17e64de8a9df2736e26728
Signed-off-by: Bart Van Assche <bvanassche@google.com>
diff --git a/init/Android.bp b/init/Android.bp
index f6f1e8c..06f696e 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -39,6 +39,7 @@
"epoll.cpp",
"import_parser.cpp",
"interface_utils.cpp",
+ "interprocess_fifo.cpp",
"keychords.cpp",
"parser.cpp",
"property_type.cpp",
@@ -467,6 +468,7 @@
"epoll_test.cpp",
"firmware_handler_test.cpp",
"init_test.cpp",
+ "interprocess_fifo_test.cpp",
"keychords_test.cpp",
"oneshot_on_test.cpp",
"persistent_properties_test.cpp",
@@ -481,7 +483,10 @@
"ueventd_test.cpp",
"util_test.cpp",
],
- static_libs: ["libinit"],
+ static_libs: [
+ "libgmock",
+ "libinit",
+ ],
test_suites: [
"cts",
diff --git a/init/interprocess_fifo.cpp b/init/interprocess_fifo.cpp
new file mode 100644
index 0000000..6e0d031
--- /dev/null
+++ b/init/interprocess_fifo.cpp
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2022 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 "interprocess_fifo.h"
+
+#include <android-base/logging.h>
+
+#include <unistd.h>
+
+using ::android::base::ErrnoError;
+using ::android::base::Error;
+using ::android::base::Result;
+
+namespace android {
+namespace init {
+
+InterprocessFifo::InterprocessFifo() noexcept : fds_({-1, -1}) {}
+
+InterprocessFifo::InterprocessFifo(InterprocessFifo&& orig) noexcept : fds_({-1, -1}) {
+ std::swap(fds_, orig.fds_);
+}
+
+InterprocessFifo::~InterprocessFifo() noexcept {
+ Close();
+}
+
+void InterprocessFifo::CloseFd(int& fd) noexcept {
+ if (fd >= 0) {
+ close(fd);
+ fd = -1;
+ }
+}
+
+void InterprocessFifo::CloseReadFd() noexcept {
+ CloseFd(fds_[0]);
+}
+
+void InterprocessFifo::CloseWriteFd() noexcept {
+ CloseFd(fds_[1]);
+}
+
+void InterprocessFifo::Close() noexcept {
+ CloseReadFd();
+ CloseWriteFd();
+}
+
+Result<void> InterprocessFifo::Initialize() noexcept {
+ if (fds_[0] >= 0) {
+ return Error() << "already initialized";
+ }
+ if (pipe(fds_.data()) < 0) { // NOLINT(android-cloexec-pipe)
+ return ErrnoError() << "pipe()";
+ }
+ return {};
+}
+
+Result<uint8_t> InterprocessFifo::Read() noexcept {
+ uint8_t byte;
+ ssize_t count = read(fds_[0], &byte, 1);
+ if (count < 0) {
+ return ErrnoError() << "read()";
+ }
+ if (count == 0) {
+ return Error() << "read() EOF";
+ }
+ DCHECK_EQ(count, 1);
+ return byte;
+}
+
+Result<void> InterprocessFifo::Write(uint8_t byte) noexcept {
+ ssize_t written = write(fds_[1], &byte, 1);
+ if (written < 0) {
+ return ErrnoError() << "write()";
+ }
+ if (written == 0) {
+ return Error() << "write() EOF";
+ }
+ DCHECK_EQ(written, 1);
+ return {};
+}
+
+} // namespace init
+} // namespace android
diff --git a/init/interprocess_fifo.h b/init/interprocess_fifo.h
new file mode 100644
index 0000000..cdaac86
--- /dev/null
+++ b/init/interprocess_fifo.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2022 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 <array>
+
+#include <android-base/result.h>
+
+namespace android {
+namespace init {
+
+// A FIFO for inter-process communication that uses a Unix pipe internally.
+class InterprocessFifo {
+ public:
+ template <typename T>
+ using Result = ::android::base::Result<T>;
+
+ InterprocessFifo() noexcept;
+ InterprocessFifo(const InterprocessFifo& orig) noexcept = delete;
+ InterprocessFifo(InterprocessFifo&& orig) noexcept;
+ InterprocessFifo& operator=(const InterprocessFifo& orig) noexcept = delete;
+ InterprocessFifo& operator=(InterprocessFifo&& orig) noexcept = delete;
+ ~InterprocessFifo() noexcept;
+ void CloseReadFd() noexcept;
+ void CloseWriteFd() noexcept;
+ void Close() noexcept;
+ Result<void> Initialize() noexcept;
+ Result<void> Write(uint8_t byte) noexcept;
+ Result<uint8_t> Read() noexcept;
+
+ private:
+ static void CloseFd(int& fd) noexcept;
+
+ std::array<int, 2> fds_;
+};
+
+} // namespace init
+} // namespace android
diff --git a/init/interprocess_fifo_test.cpp b/init/interprocess_fifo_test.cpp
new file mode 100644
index 0000000..81cfbac
--- /dev/null
+++ b/init/interprocess_fifo_test.cpp
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2022 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 "interprocess_fifo.h"
+
+#include <android-base/result-gmock.h>
+#include <gtest/gtest.h>
+
+#define ASSERT_OK(e) ASSERT_THAT(e, Ok())
+#define ASSERT_NOT_OK(e) ASSERT_THAT(e, Not(Ok()))
+
+using ::android::base::Result;
+using ::android::base::testing::Ok;
+using ::testing::Not;
+
+namespace android {
+namespace init {
+
+TEST(FifoTest, WriteAndRead) {
+ InterprocessFifo fifo;
+ ASSERT_OK(fifo.Initialize());
+ ASSERT_OK(fifo.Write('a'));
+ ASSERT_OK(fifo.Write('b'));
+ Result<uint8_t> result = fifo.Read();
+ ASSERT_OK(result);
+ EXPECT_EQ(*result, 'a');
+ result = fifo.Read();
+ ASSERT_OK(result);
+ EXPECT_EQ(*result, 'b');
+ InterprocessFifo fifo2 = std::move(fifo);
+ ASSERT_NOT_OK(fifo.Write('c'));
+ ASSERT_NOT_OK(fifo.Read());
+ ASSERT_OK(fifo2.Write('d'));
+ result = fifo2.Read();
+ ASSERT_OK(result);
+ EXPECT_EQ(*result, 'd');
+}
+
+} // namespace init
+} // namespace android
diff --git a/init/service.cpp b/init/service.cpp
index 6a9343d..331cd88 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -38,6 +38,7 @@
#include <string>
+#include "interprocess_fifo.h"
#include "lmkd_service.h"
#include "service_list.h"
#include "util.h"
@@ -442,14 +443,6 @@
return {};
}
-static void ClosePipe(const std::array<int, 2>* pipe) {
- for (const auto fd : *pipe) {
- if (fd >= 0) {
- close(fd);
- }
- }
-}
-
Result<void> Service::CheckConsole() {
if (!(flags_ & SVC_CONSOLE)) {
return {};
@@ -514,7 +507,7 @@
// Enters namespaces, sets environment variables, writes PID files and runs the service executable.
void Service::RunService(const std::vector<Descriptor>& descriptors,
- std::unique_ptr<std::array<int, 2>, decltype(&ClosePipe)> pipefd) {
+ InterprocessFifo cgroups_activated) {
if (auto result = EnterNamespaces(namespaces_, name_, mount_namespace_); !result.ok()) {
LOG(FATAL) << "Service '" << name_ << "' failed to set up namespaces: " << result.error();
}
@@ -536,12 +529,12 @@
// Wait until the cgroups have been created and until the cgroup controllers have been
// activated.
- char byte = 0;
- if (read((*pipefd)[0], &byte, 1) < 0) {
- PLOG(ERROR) << "failed to read from notification channel";
+ Result<uint8_t> byte = cgroups_activated.Read();
+ if (!byte.ok()) {
+ LOG(ERROR) << name_ << ": failed to read from notification channel: " << byte.error();
}
- pipefd.reset();
- if (!byte) {
+ cgroups_activated.Close();
+ if (!*byte) {
LOG(FATAL) << "Service '" << name_ << "' failed to start due to a fatal error";
_exit(EXIT_FAILURE);
}
@@ -605,10 +598,10 @@
return {};
}
- std::unique_ptr<std::array<int, 2>, decltype(&ClosePipe)> pipefd(new std::array<int, 2>{-1, -1},
- ClosePipe);
- if (pipe(pipefd->data()) < 0) {
- return ErrnoError() << "pipe()";
+ InterprocessFifo cgroups_activated;
+
+ if (Result<void> result = cgroups_activated.Initialize(); !result.ok()) {
+ return result;
}
if (Result<void> result = CheckConsole(); !result.ok()) {
@@ -667,8 +660,11 @@
if (pid == 0) {
umask(077);
- RunService(descriptors, std::move(pipefd));
+ cgroups_activated.CloseWriteFd();
+ RunService(descriptors, std::move(cgroups_activated));
_exit(127);
+ } else {
+ cgroups_activated.CloseReadFd();
}
if (pid < 0) {
@@ -697,8 +693,9 @@
limit_percent_ != -1 || !limit_property_.empty();
errno = -createProcessGroup(proc_attr_.uid, pid_, use_memcg);
if (errno != 0) {
- if (char byte = 0; write((*pipefd)[1], &byte, 1) < 0) {
- return ErrnoError() << "sending notification failed";
+ Result<void> result = cgroups_activated.Write(0);
+ if (!result.ok()) {
+ return Error() << "Sending notification failed: " << result.error();
}
return Error() << "createProcessGroup(" << proc_attr_.uid << ", " << pid_
<< ") failed for service '" << name_ << "'";
@@ -720,8 +717,8 @@
LmkdRegister(name_, proc_attr_.uid, pid_, oom_score_adjust_);
}
- if (char byte = 1; write((*pipefd)[1], &byte, 1) < 0) {
- return ErrnoError() << "sending notification failed";
+ if (Result<void> result = cgroups_activated.Write(1); !result.ok()) {
+ return Error() << "Sending cgroups activated notification failed: " << result.error();
}
NotifyStateChange("running");
diff --git a/init/service.h b/init/service.h
index ab19865..b2c9909 100644
--- a/init/service.h
+++ b/init/service.h
@@ -31,6 +31,7 @@
#include "action.h"
#include "capabilities.h"
+#include "interprocess_fifo.h"
#include "keyword_map.h"
#include "mount_namespace.h"
#include "parser.h"
@@ -154,9 +155,7 @@
void ResetFlagsForStart();
Result<void> CheckConsole();
void ConfigureMemcg();
- void RunService(
- const std::vector<Descriptor>& descriptors,
- std::unique_ptr<std::array<int, 2>, void (*)(const std::array<int, 2>* pipe)> pipefd);
+ void RunService(const std::vector<Descriptor>& descriptors, InterprocessFifo cgroups_activated);
void SetMountNamespace();
static unsigned long next_start_order_;
static bool is_exec_service_running_;