base/scoped_environment_variable_override.h

   1 // Copyright 2017 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_SCOPED_ENVIRONMENT_VARIABLE_OVERRIDE_H_
   6 #define BASE_SCOPED_ENVIRONMENT_VARIABLE_OVERRIDE_H_
   7
   8 #include <memory>
   9 #include <string>
  10
  11 #include "base/base_export.h"
  12
  13 namespace base {
  14
  15 class Environment;
  16
  17 // Helper class to override |variable_name| environment variable to |value| for
  18 // the lifetime of this class. Upon destruction, the previous value is restored.
  19 class BASE_EXPORT ScopedEnvironmentVariableOverride final {
  20  public:
  21   ScopedEnvironmentVariableOverride(const std::string& variable_name,
  22                                     const std::string& value);
  23   // Unset the variable.
  24   explicit ScopedEnvironmentVariableOverride(const std::string& variable_name);
  25   ScopedEnvironmentVariableOverride(ScopedEnvironmentVariableOverride&&);
  26   ScopedEnvironmentVariableOverride& operator=(
  27       ScopedEnvironmentVariableOverride&&);
  28   ~ScopedEnvironmentVariableOverride();
  29
  30   base::Environment* GetEnv() { return environment_.get(); }
  31   bool IsOverridden() { return overridden_; }
  32   bool WasSet() { return was_set_; }
  33
  34  private:
  35   ScopedEnvironmentVariableOverride(const std::string& variable_name,
  36                                     const std::string& value,
  37                                     bool unset_var);
  38   std::unique_ptr<Environment> environment_;
  39   std::string variable_name_;
  40   bool overridden_;
  41   bool was_set_;
  42   std::string old_value_;
  43 };
  44
  45 }  // namespace base
  46
  47 #endif  // BASE_SCOPED_ENVIRONMENT_VARIABLE_OVERRIDE_H_