scoped_set_env.cc (2014B)
1 // Copyright 2019 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 #include "absl/base/internal/scoped_set_env.h" 16 17 #ifdef _WIN32 18 #include <windows.h> 19 #endif 20 21 #include <cstdlib> 22 23 #include "absl/base/internal/raw_logging.h" 24 25 namespace absl { 26 ABSL_NAMESPACE_BEGIN 27 namespace base_internal { 28 29 namespace { 30 31 #ifdef _WIN32 32 const int kMaxEnvVarValueSize = 1024; 33 #endif 34 35 void SetEnvVar(const char* name, const char* value) { 36 #ifdef _WIN32 37 SetEnvironmentVariableA(name, value); 38 #else 39 if (value == nullptr) { 40 ::unsetenv(name); 41 } else { 42 ::setenv(name, value, 1); 43 } 44 #endif 45 } 46 47 } // namespace 48 49 ScopedSetEnv::ScopedSetEnv(const char* var_name, const char* new_value) 50 : var_name_(var_name), was_unset_(false) { 51 #ifdef _WIN32 52 char buf[kMaxEnvVarValueSize]; 53 auto get_res = GetEnvironmentVariableA(var_name_.c_str(), buf, sizeof(buf)); 54 ABSL_INTERNAL_CHECK(get_res < sizeof(buf), "value exceeds buffer size"); 55 56 if (get_res == 0) { 57 was_unset_ = (GetLastError() == ERROR_ENVVAR_NOT_FOUND); 58 } else { 59 old_value_.assign(buf, get_res); 60 } 61 62 SetEnvironmentVariableA(var_name_.c_str(), new_value); 63 #else 64 const char* val = ::getenv(var_name_.c_str()); 65 if (val == nullptr) { 66 was_unset_ = true; 67 } else { 68 old_value_ = val; 69 } 70 #endif 71 72 SetEnvVar(var_name_.c_str(), new_value); 73 } 74 75 ScopedSetEnv::~ScopedSetEnv() { 76 SetEnvVar(var_name_.c_str(), was_unset_ ? nullptr : old_value_.c_str()); 77 } 78 79 } // namespace base_internal 80 ABSL_NAMESPACE_END 81 } // namespace absl