scoped_set_env.cc
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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 
16 
17 #ifdef _WIN32
18 #include <windows.h>
19 #endif
20 
21 #include <cstdlib>
22 
24 
25 namespace absl {
26 namespace base_internal {
27 
28 namespace {
29 
30 #ifdef _WIN32
31 const int kMaxEnvVarValueSize = 1024;
32 #endif
33 
34 void SetEnvVar(const char* name, const char* value) {
35 #ifdef _WIN32
36  SetEnvironmentVariableA(name, value);
37 #else
38  if (value == nullptr) {
39  ::unsetenv(name);
40  } else {
41  ::setenv(name, value, 1);
42  }
43 #endif
44 }
45 
46 } // namespace
47 
48 ScopedSetEnv::ScopedSetEnv(const char* var_name, const char* new_value)
49  : var_name_(var_name), was_unset_(false) {
50 #ifdef _WIN32
51  char buf[kMaxEnvVarValueSize];
52  auto get_res = GetEnvironmentVariableA(var_name_.c_str(), buf, sizeof(buf));
53  ABSL_INTERNAL_CHECK(get_res < sizeof(buf), "value exceeds buffer size");
54 
55  if (get_res == 0) {
56  was_unset_ = (GetLastError() == ERROR_ENVVAR_NOT_FOUND);
57  } else {
58  old_value_.assign(buf, get_res);
59  }
60 
61  SetEnvironmentVariableA(var_name_.c_str(), new_value);
62 #else
63  const char* val = ::getenv(var_name_.c_str());
64  if (val == nullptr) {
65  was_unset_ = true;
66  } else {
67  old_value_ = val;
68  }
69 #endif
70 
71  SetEnvVar(var_name_.c_str(), new_value);
72 }
73 
75  SetEnvVar(var_name_.c_str(), was_unset_ ? nullptr : old_value_.c_str());
76 }
77 
78 } // namespace base_internal
79 } // namespace absl
#define ABSL_INTERNAL_CHECK(condition, message)
Definition: raw_logging.h:83
ScopedSetEnv(const char *var_name, const char *new_value)
char buf[N]
Definition: algorithm.h:29
size_t value
char name[1]
Definition: mutex.cc:296


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autogenerated on Wed Jun 19 2019 19:19:57