From c996a8e73ea0148af08d4585e2136ffa950932a4 Mon Sep 17 00:00:00 2001
From: Tom Cherry <tomcherry@google.com>
Date: Wed, 5 Apr 2017 14:15:31 -0700
Subject: [PATCH] Add android::base::ScopeGuard

Taken from bionic/libc/private/ScopeGuard.h.

Test: New unit tests
Change-Id: If83c1990efbf294aee0b5d40a7a9ac326e5e765e
---
 base/Android.bp                        |  1 +
 base/include/android-base/scopeguard.h | 60 ++++++++++++++++++++++++++
 base/scopeguard_test.cpp               | 46 ++++++++++++++++++++
 3 files changed, 107 insertions(+)
 create mode 100644 base/include/android-base/scopeguard.h
 create mode 100644 base/scopeguard_test.cpp

diff --git a/base/Android.bp b/base/Android.bp
index 121da4214..3af768614 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -98,6 +98,7 @@ cc_test {
         "parseint_test.cpp",
         "parsenetaddress_test.cpp",
         "quick_exit_test.cpp",
+        "scopeguard_test.cpp",
         "stringprintf_test.cpp",
         "strings_test.cpp",
         "test_main.cpp",
diff --git a/base/include/android-base/scopeguard.h b/base/include/android-base/scopeguard.h
new file mode 100644
index 000000000..abcf4bca4
--- /dev/null
+++ b/base/include/android-base/scopeguard.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#ifndef ANDROID_BASE_SCOPEGUARD_H
+#define ANDROID_BASE_SCOPEGUARD_H
+
+#include <utility>  // for std::move
+
+namespace android {
+namespace base {
+
+template <typename F>
+class ScopeGuard {
+ public:
+  ScopeGuard(F f) : f_(f), active_(true) {}
+
+  ScopeGuard(ScopeGuard&& that) : f_(std::move(that.f_)), active_(that.active_) {
+    that.active_ = false;
+  }
+
+  ~ScopeGuard() {
+    if (active_) f_();
+  }
+
+  ScopeGuard() = delete;
+  ScopeGuard(const ScopeGuard&) = delete;
+  void operator=(const ScopeGuard&) = delete;
+  void operator=(ScopeGuard&& that) = delete;
+
+  void Disable() { active_ = false; }
+
+  bool active() const { return active_; }
+
+ private:
+  F f_;
+  bool active_;
+};
+
+template <typename T>
+ScopeGuard<T> make_scope_guard(T f) {
+  return ScopeGuard<T>(f);
+}
+
+}  // namespace base
+}  // namespace android
+
+#endif  // ANDROID_BASE_SCOPEGUARD_H
diff --git a/base/scopeguard_test.cpp b/base/scopeguard_test.cpp
new file mode 100644
index 000000000..e11154a57
--- /dev/null
+++ b/base/scopeguard_test.cpp
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2017 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/scopeguard.h"
+
+#include <utility>
+
+#include <gtest/gtest.h>
+
+TEST(scopeguard, normal) {
+  bool guarded_var = true;
+  {
+    auto scopeguard = android::base::make_scope_guard([&guarded_var] { guarded_var = false; });
+  }
+  ASSERT_FALSE(guarded_var);
+}
+
+TEST(scopeguard, disabled) {
+  bool guarded_var = true;
+  {
+    auto scopeguard = android::base::make_scope_guard([&guarded_var] { guarded_var = false; });
+    scopeguard.Disable();
+  }
+  ASSERT_TRUE(guarded_var);
+}
+
+TEST(scopeguard, moved) {
+  int guarded_var = true;
+  auto scopeguard = android::base::make_scope_guard([&guarded_var] { guarded_var = false; });
+  { decltype(scopeguard) new_guard(std::move(scopeguard)); }
+  EXPECT_FALSE(scopeguard.active());
+  ASSERT_FALSE(guarded_var);
+}