tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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environment.cc (3704B)

      1 // Copyright 2012 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 #include "base/environment.h"
      6 
      7 #include "base/memory/ptr_util.h"
      8 #include "base/strings/string_piece.h"
      9 #include "base/strings/string_util.h"
     10 #include "base/strings/utf_string_conversions.h"
     11 #include "build/build_config.h"
     12 
     13 #if BUILDFLAG(IS_WIN)
     14 #include <windows.h>
     15 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
     16 #include <stdlib.h>
     17 #endif
     18 
     19 namespace base {
     20 
     21 namespace {
     22 
     23 class EnvironmentImpl : public Environment {
     24 public:
     25  bool GetVar(StringPiece variable_name, 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 (IsAsciiLower(first_char))
     36      alternate_case_var = ToUpperASCII(variable_name);
     37    else if (IsAsciiUpper(first_char))
     38      alternate_case_var = ToLowerASCII(variable_name);
     39    else
     40      return false;
     41    return GetVarImpl(alternate_case_var, result);
     42  }
     43 
     44  bool SetVar(StringPiece variable_name,
     45              const std::string& new_value) override {
     46    return SetVarImpl(variable_name, new_value);
     47  }
     48 
     49  bool UnSetVar(StringPiece variable_name) override {
     50    return UnSetVarImpl(variable_name);
     51  }
     52 
     53 private:
     54  bool GetVarImpl(StringPiece variable_name, std::string* result) {
     55 #if BUILDFLAG(IS_WIN)
     56    DWORD value_length =
     57        ::GetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), nullptr, 0);
     58    if (value_length == 0)
     59      return false;
     60    if (result) {
     61      std::unique_ptr<wchar_t[]> value(new wchar_t[value_length]);
     62      ::GetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), value.get(),
     63                               value_length);
     64      *result = WideToUTF8(value.get());
     65    }
     66    return true;
     67 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
     68    const char* env_value = getenv(variable_name.data());
     69    if (!env_value)
     70      return false;
     71    // Note that the variable may be defined but empty.
     72    if (result)
     73      *result = env_value;
     74    return true;
     75 #endif
     76  }
     77 
     78  bool SetVarImpl(StringPiece variable_name, const std::string& new_value) {
     79 #if BUILDFLAG(IS_WIN)
     80    // On success, a nonzero value is returned.
     81    return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(),
     82                                    UTF8ToWide(new_value).c_str());
     83 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
     84    // On success, zero is returned.
     85    return !setenv(variable_name.data(), new_value.c_str(), 1);
     86 #endif
     87  }
     88 
     89  bool UnSetVarImpl(StringPiece variable_name) {
     90 #if BUILDFLAG(IS_WIN)
     91    // On success, a nonzero value is returned.
     92    return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), nullptr);
     93 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
     94    // On success, zero is returned.
     95    return !unsetenv(variable_name.data());
     96 #endif
     97  }
     98 };
     99 
    100 }  // namespace
    101 
    102 namespace env_vars {
    103 
    104 #if BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
    105 // On Posix systems, this variable contains the location of the user's home
    106 // directory. (e.g, /home/username/).
    107 const char kHome[] = "HOME";
    108 #endif
    109 
    110 }  // namespace env_vars
    111 
    112 Environment::~Environment() = default;
    113 
    114 // static
    115 std::unique_ptr<Environment> Environment::Create() {
    116  return std::make_unique<EnvironmentImpl>();
    117 }
    118 
    119 bool Environment::HasVar(StringPiece variable_name) {
    120  return GetVar(variable_name, nullptr);
    121 }
    122 
    123 }  // namespace base