1/* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef LIBMEMUNREACHABLE_SCOPED_DISABLE_MALLOC_H_ 18#define LIBMEMUNREACHABLE_SCOPED_DISABLE_MALLOC_H_ 19 20#include <memory> 21 22#include "android-base/macros.h" 23 24#include "bionic.h" 25#include "log.h" 26#include "ScopedAlarm.h" 27 28class DisableMallocGuard{ 29 public: 30 DisableMallocGuard() : disabled_(false){} 31 ~DisableMallocGuard() { 32 Enable(); 33 } 34 35 void Disable() { 36 if (!disabled_) { 37 malloc_disable(); 38 disabled_ = true; 39 } 40 } 41 42 void Enable() { 43 if (disabled_) { 44 malloc_enable(); 45 disabled_ = false; 46 } 47 } 48 private: 49 DISALLOW_COPY_AND_ASSIGN(DisableMallocGuard); 50 bool disabled_; 51}; 52 53// Any calls to malloc or free from this thread will deadlock as long as this 54// object is in scope. Calls to malloc from other threads may succeed (for 55// example if the allocation is satisfied out of the thread's tcache), or may 56// block until the object is destroyed. 57// 58// Don't call fork() while malloc is disabled, it needs the same locks held 59// here. 60class ScopedDisableMalloc { 61 public: 62 ScopedDisableMalloc() { 63 disable_malloc_.Disable(); 64 } 65 66 ~ScopedDisableMalloc() { 67 disable_malloc_.Enable(); 68 } 69 70 private: 71 DISALLOW_COPY_AND_ASSIGN(ScopedDisableMalloc); 72 DisableMallocGuard disable_malloc_; 73}; 74 75class ScopedDisableMallocTimeout { 76 public: 77 ScopedDisableMallocTimeout(std::chrono::milliseconds timeout = std::chrono::milliseconds(2000)) : 78 timeout_(timeout), timed_out_(false), disable_malloc_() { 79 Disable(); 80 } 81 82 ~ScopedDisableMallocTimeout() { 83 Enable(); 84 } 85 86 bool timed_out() { 87 return timed_out_; 88 } 89 90 void Enable() { 91 disable_malloc_.Enable(); 92 alarm_ = nullptr; 93 } 94 95 void Disable() { 96 // set up the alarm before disabling malloc so unique_ptr can be used 97 alarm_ = std::make_unique<ScopedAlarm>(timeout_, [&]() { 98 disable_malloc_.Enable(); 99 timed_out_ = true; 100 }); 101 102 disable_malloc_.Disable(); 103 } 104 105 private: 106 DISALLOW_COPY_AND_ASSIGN(ScopedDisableMallocTimeout); 107 std::chrono::milliseconds timeout_; 108 bool timed_out_; 109 std::unique_ptr<ScopedAlarm> alarm_; 110 DisableMallocGuard disable_malloc_; 111}; 112 113#endif // LIBMEMUNREACHABLE_SCOPED_DISABLE_MALLOC_H_ 114