1// Copyright 2018 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#ifndef ABSL_BASE_INTERNAL_HIDE_PTR_H_
16#define ABSL_BASE_INTERNAL_HIDE_PTR_H_
17
18#include <cstdint>
19
20namespace absl {
21namespace base_internal {
22
23// Arbitrary value with high bits set. Xor'ing with it is unlikely
24// to map one valid pointer to another valid pointer.
25constexpr uintptr_t HideMask() {
26 return (uintptr_t{0xF03A5F7BU} << (sizeof(uintptr_t) - 4) * 8) | 0xF03A5F7BU;
27}
28
29// Hide a pointer from the leak checker. For internal use only.
30// Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr
31// and all objects reachable from ptr to be ignored by the leak checker.
32template <class T>
33inline uintptr_t HidePtr(T* ptr) {
34 return reinterpret_cast<uintptr_t>(ptr) ^ HideMask();
35}
36
37// Return a pointer that has been hidden from the leak checker.
38// For internal use only.
39template <class T>
40inline T* UnhidePtr(uintptr_t hidden) {
41 return reinterpret_cast<T*>(hidden ^ HideMask());
42}
43
44} // namespace base_internal
45} // namespace absl
46
47#endif // ABSL_BASE_INTERNAL_HIDE_PTR_H_
48