base/environment.cc

   1 // Copyright (c) 2012 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 #include "base/environment.h"
   6
   7 #if defined(OS_POSIX)
   8 #include <stdlib.h>
   9 #elif defined(OS_WIN)
  10 #include <windows.h>
  11 #endif
  12
  13 #include "base/strings/string_util.h"
  14
  15 #if defined(OS_WIN)
  16 #include "base/memory/scoped_ptr.h"
  17 #include "base/strings/utf_string_conversions.h"
  18 #endif
  19
  20 namespace {
  21
  22 class EnvironmentImpl : public base::Environment {
  23  public:
  24   virtual bool GetVar(const char* variable_name,
  25                       std::string* result) OVERRIDE {
  26     if (GetVarImpl(variable_name, result))
  27       return true;
  28
  29     // Some commonly used variable names are uppercase while others
  30     // are lowercase, which is inconsistent. Let's try to be helpful
  31     // and look for a variable name with the reverse case.
  32     // I.e. HTTP_PROXY may be http_proxy for some users/systems.
  33     char first_char = variable_name[0];
  34     std::string alternate_case_var;
  35     if (first_char >= 'a' && first_char <= 'z')
  36       alternate_case_var = StringToUpperASCII(std::string(variable_name));
  37     else if (first_char >= 'A' && first_char <= 'Z')
  38       alternate_case_var = StringToLowerASCII(std::string(variable_name));
  39     else
  40       return false;
  41     return GetVarImpl(alternate_case_var.c_str(), result);
  42   }
  43
  44   virtual bool SetVar(const char* variable_name,
  45                       const std::string& new_value) OVERRIDE {
  46     return SetVarImpl(variable_name, new_value);
  47   }
  48
  49   virtual bool UnSetVar(const char* variable_name) OVERRIDE {
  50     return UnSetVarImpl(variable_name);
  51   }
  52
  53  private:
  54   bool GetVarImpl(const char* variable_name, std::string* result) {
  55 #if defined(OS_POSIX)
  56     const char* env_value = getenv(variable_name);
  57     if (!env_value)
  58       return false;
  59     // Note that the variable may be defined but empty.
  60     if (result)
  61       *result = env_value;
  62     return true;
  63 #elif defined(OS_WIN)
  64     DWORD value_length = ::GetEnvironmentVariable(
  65         UTF8ToWide(variable_name).c_str(), NULL, 0);
  66     if (value_length == 0)
  67       return false;
  68     if (result) {
  69       scoped_ptr<wchar_t[]> value(new wchar_t[value_length]);
  70       ::GetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), value.get(),
  71                                value_length);
  72       *result = WideToUTF8(value.get());
  73     }
  74     return true;
  75 #else
  76 #error need to port
  77 #endif
  78   }
  79
  80   bool SetVarImpl(const char* variable_name, const std::string& new_value) {
  81 #if defined(OS_POSIX)
  82     // On success, zero is returned.
  83     return !setenv(variable_name, new_value.c_str(), 1);
  84 #elif defined(OS_WIN)
  85     // On success, a nonzero value is returned.
  86     return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(),
  87                                     UTF8ToWide(new_value).c_str());
  88 #endif
  89   }
  90
  91   bool UnSetVarImpl(const char* variable_name) {
  92 #if defined(OS_POSIX)
  93     // On success, zero is returned.
  94     return !unsetenv(variable_name);
  95 #elif defined(OS_WIN)
  96     // On success, a nonzero value is returned.
  97     return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), NULL);
  98 #endif
  99   }
 100 };
 101
 102 }  // namespace
 103
 104 namespace base {
 105
 106 namespace env_vars {
 107
 108 #if defined(OS_POSIX)
 109 // On Posix systems, this variable contains the location of the user's home
 110 // directory. (e.g, /home/username/).
 111 const char kHome[] = "HOME";
 112 #endif
 113
 114 }  // namespace env_vars
 115
 116 Environment::~Environment() {}
 117
 118 // static
 119 Environment* Environment::Create() {
 120   return new EnvironmentImpl();
 121 }
 122
 123 bool Environment::HasVar(const char* variable_name) {
 124   return GetVar(variable_name, NULL);
 125 }
 126
 127 }  // namespace base