base: add quick_exit emulation.

Bug: http://b/31468413
Change-Id: Ie15fcb8ff0613d01a0eb7437a2cb37283aa52bab
Test: mma, libbase_test on Linux/Windows

base/Android.bp

@@ -28,6 +28,7 @@ cc_library {
         "file.cpp",
         "logging.cpp",
         "parsenetaddress.cpp",
+        "quick_exit.cpp",
         "stringprintf.cpp",
         "strings.cpp",
         "test_utils.cpp",
@@ -71,6 +72,7 @@ cc_test {
         "logging_test.cpp",
         "parseint_test.cpp",
         "parsenetaddress_test.cpp",
+        "quick_exit_test.cpp",
         "stringprintf_test.cpp",
         "strings_test.cpp",
         "test_main.cpp",

base/include/android-base/quick_exit.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016 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 <stdlib.h>
+
+// Provide emulation for at_quick_exit/quick_exit on platforms that don't have it.
+namespace android {
+namespace base {
+
+// Bionic and glibc have quick_exit, Darwin and Windows don't.
+#if !defined(__linux__)
+  void quick_exit(int exit_code) __attribute__((noreturn));
+  int at_quick_exit(void (*func)());
+#else
+  using ::at_quick_exit;
+  using ::quick_exit;
+#endif
+}
+}

base/quick_exit.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2016 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 "android-base/quick_exit.h"
+
+#if !defined(__linux__)
+
+#include <mutex>
+#include <vector>
+
+#include "android-base/mutex.h"
+
+namespace android {
+namespace base {
+
+static std::mutex quick_exit_mutex;
+static std::vector<void(*)()> quick_exit_handlers;
+
+void quick_exit(int exit_code) {
+  std::lock_guard<std::mutex> lock(quick_exit_mutex);
+  for (auto it = quick_exit_handlers.rbegin(); it != quick_exit_handlers.rend(); ++it) {
+    (*it)();
+  }
+  _Exit(exit_code);
+}
+
+int at_quick_exit(void (*func)()) {
+  std::lock_guard<std::mutex> lock(quick_exit_mutex);
+  quick_exit_handlers.push_back(func);
+  return 0;
+}
+
+}  // namespace base
+}  // namespace android
+#endif

base/quick_exit_test.cpp

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2016 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 "android-base/quick_exit.h"
+
+#include <gtest/gtest.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <string>
+
+#include "android-base/test_utils.h"
+
+// These tests are a bit sketchy, since each test run adds global state that affects subsequent
+// tests (including ones not in this file!). Exit with 0 in Exiter and stick the at_quick_exit test
+// at the end to hack around this.
+struct Exiter {
+  ~Exiter() {
+    _Exit(0);
+  }
+};
+
+TEST(quick_exit, smoke) {
+  ASSERT_EXIT(android::base::quick_exit(123), testing::ExitedWithCode(123), "");
+}
+
+TEST(quick_exit, skip_static_destructors) {
+  static Exiter exiter;
+  ASSERT_EXIT(android::base::quick_exit(123), testing::ExitedWithCode(123), "");
+}
+
+TEST(quick_exit, at_quick_exit) {
+  static int counter = 4;
+  // "Functions passed to at_quick_exit are called in reverse order of their registration."
+  ASSERT_EQ(0, android::base::at_quick_exit([]() { _exit(counter); }));
+  ASSERT_EQ(0, android::base::at_quick_exit([]() { counter += 2; }));
+  ASSERT_EQ(0, android::base::at_quick_exit([]() { counter *= 10; }));
+  ASSERT_EXIT(android::base::quick_exit(123), testing::ExitedWithCode(42), "");
+}