hide_ptr.h (1677B)
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 20 #include "absl/base/config.h" 21 22 namespace absl { 23 ABSL_NAMESPACE_BEGIN 24 namespace base_internal { 25 26 // Arbitrary value with high bits set. Xor'ing with it is unlikely 27 // to map one valid pointer to another valid pointer. 28 constexpr uintptr_t HideMask() { 29 return (uintptr_t{0xF03A5F7BU} << (sizeof(uintptr_t) - 4) * 8) | 0xF03A5F7BU; 30 } 31 32 // Hide a pointer from the leak checker. For internal use only. 33 // Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr 34 // and all objects reachable from ptr to be ignored by the leak checker. 35 template <class T> 36 inline uintptr_t HidePtr(T* ptr) { 37 return reinterpret_cast<uintptr_t>(ptr) ^ HideMask(); 38 } 39 40 // Return a pointer that has been hidden from the leak checker. 41 // For internal use only. 42 template <class T> 43 inline T* UnhidePtr(uintptr_t hidden) { 44 return reinterpret_cast<T*>(hidden ^ HideMask()); 45 } 46 47 } // namespace base_internal 48 ABSL_NAMESPACE_END 49 } // namespace absl 50 51 #endif // ABSL_BASE_INTERNAL_HIDE_PTR_H_