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