1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 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_ENVIRONMENT_H_ 6 #define BASE_ENVIRONMENT_H_ 7 8 #include <map> 9 #include <memory> 10 #include <string> 11 12 #include "base/base_export.h" 13 #include "base/strings/string16.h" 14 #include "base/strings/string_piece.h" 15 #include "build/build_config.h" 16 17 namespace base { 18 19 namespace env_vars { 20 21 #if defined(OS_POSIX) 22 BASE_EXPORT extern const char kHome[]; 23 #endif 24 25 } // namespace env_vars 26 27 class BASE_EXPORT Environment { 28 public: 29 virtual ~Environment(); 30 31 // Returns the appropriate platform-specific instance. 32 static std::unique_ptr<Environment> Create(); 33 34 // Gets an environment variable's value and stores it in |result|. 35 // Returns false if the key is unset. 36 virtual bool GetVar(StringPiece variable_name, std::string* result) = 0; 37 38 // Syntactic sugar for GetVar(variable_name, nullptr); 39 virtual bool HasVar(StringPiece variable_name); 40 41 // Returns true on success, otherwise returns false. 42 virtual bool SetVar(StringPiece variable_name, 43 const std::string& new_value) = 0; 44 45 // Returns true on success, otherwise returns false. 46 virtual bool UnSetVar(StringPiece variable_name) = 0; 47 }; 48 49 50 #if defined(OS_WIN) 51 52 typedef string16 NativeEnvironmentString; 53 typedef std::map<NativeEnvironmentString, NativeEnvironmentString> 54 EnvironmentMap; 55 56 // Returns a modified environment vector constructed from the given environment 57 // and the list of changes given in |changes|. Each key in the environment is 58 // matched against the first element of the pairs. In the event of a match, the 59 // value is replaced by the second of the pair, unless the second is empty, in 60 // which case the key-value is removed. 61 // 62 // This Windows version takes and returns a Windows-style environment block 63 // which is a concatenated list of null-terminated 16-bit strings. The end is 64 // marked by a double-null terminator. The size of the returned string will 65 // include the terminators. 66 BASE_EXPORT string16 AlterEnvironment(const wchar_t* env, 67 const EnvironmentMap& changes); 68 69 #elif defined(OS_POSIX) 70 71 typedef std::string NativeEnvironmentString; 72 typedef std::map<NativeEnvironmentString, NativeEnvironmentString> 73 EnvironmentMap; 74 75 // See general comments for the Windows version above. 76 // 77 // This Posix version takes and returns a Posix-style environment block, which 78 // is a null-terminated list of pointers to null-terminated strings. The 79 // returned array will have appended to it the storage for the array itself so 80 // there is only one pointer to manage, but this means that you can't copy the 81 // array without keeping the original around. 82 BASE_EXPORT std::unique_ptr<char* []> AlterEnvironment( 83 const char* const* env, 84 const EnvironmentMap& changes); 85 86 #endif 87 88 } // namespace base 89 90 #endif // BASE_ENVIRONMENT_H_ 91
