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 "ScopedAlarm.h" 25 #include "bionic.h" 26 #include "log.h" 27 28 namespace android { 29 30 class DisableMallocGuard { 31 public: DisableMallocGuard()32 DisableMallocGuard() : disabled_(false) {} ~DisableMallocGuard()33 ~DisableMallocGuard() { Enable(); } 34 Disable()35 void Disable() { 36 if (!disabled_) { 37 disabled_ = true; 38 malloc_disable(); 39 } 40 } 41 Enable()42 void Enable() { 43 if (disabled_) { 44 malloc_enable(); 45 disabled_ = false; 46 } 47 } 48 49 private: 50 DISALLOW_COPY_AND_ASSIGN(DisableMallocGuard); 51 bool disabled_; 52 }; 53 54 // Any calls to malloc or free from this thread will deadlock as long as this 55 // object is in scope. Calls to malloc from other threads may succeed (for 56 // example if the allocation is satisfied out of the thread's tcache), or may 57 // block until the object is destroyed. 58 // 59 // Don't call fork() while malloc is disabled, it needs the same locks held 60 // here. 61 class ScopedDisableMalloc { 62 public: ScopedDisableMalloc()63 ScopedDisableMalloc() { disable_malloc_.Disable(); } 64 ~ScopedDisableMalloc()65 ~ScopedDisableMalloc() { disable_malloc_.Enable(); } 66 67 private: 68 DISALLOW_COPY_AND_ASSIGN(ScopedDisableMalloc); 69 DisableMallocGuard disable_malloc_; 70 }; 71 72 class ScopedDisableMallocTimeout { 73 public: 74 explicit ScopedDisableMallocTimeout(std::chrono::milliseconds timeout = std::chrono::seconds(10)) timeout_(timeout)75 : timeout_(timeout), timed_out_(false), disable_malloc_() { 76 Disable(); 77 } 78 ~ScopedDisableMallocTimeout()79 ~ScopedDisableMallocTimeout() { Enable(); } 80 timed_out()81 bool timed_out() { return timed_out_; } 82 Enable()83 void Enable() { 84 disable_malloc_.Enable(); 85 alarm_ = nullptr; 86 } 87 Disable()88 void Disable() { 89 // set up the alarm before disabling malloc so unique_ptr can be used 90 alarm_ = std::make_unique<ScopedAlarm>(timeout_, [&]() { 91 disable_malloc_.Enable(); 92 timed_out_ = true; 93 }); 94 95 disable_malloc_.Disable(); 96 } 97 98 private: 99 DISALLOW_COPY_AND_ASSIGN(ScopedDisableMallocTimeout); 100 std::chrono::milliseconds timeout_; 101 bool timed_out_; 102 std::unique_ptr<ScopedAlarm> alarm_; 103 DisableMallocGuard disable_malloc_; 104 }; 105 106 } // namespace android 107 108 #endif // LIBMEMUNREACHABLE_SCOPED_DISABLE_MALLOC_H_ 109