errno_saver.h (1321B)
1 // Copyright 2017 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_ERRNO_SAVER_H_ 16 #define ABSL_BASE_INTERNAL_ERRNO_SAVER_H_ 17 18 #include <cerrno> 19 20 #include "absl/base/config.h" 21 22 namespace absl { 23 ABSL_NAMESPACE_BEGIN 24 namespace base_internal { 25 26 // `ErrnoSaver` captures the value of `errno` upon construction and restores it 27 // upon deletion. It is used in low-level code and must be super fast. Do not 28 // add instrumentation, even in debug modes. 29 class ErrnoSaver { 30 public: 31 ErrnoSaver() : saved_errno_(errno) {} 32 ~ErrnoSaver() { errno = saved_errno_; } 33 int operator()() const { return saved_errno_; } 34 35 private: 36 const int saved_errno_; 37 }; 38 39 } // namespace base_internal 40 ABSL_NAMESPACE_END 41 } // namespace absl 42 43 #endif // ABSL_BASE_INTERNAL_ERRNO_SAVER_H_