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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/environment.h"
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <utility>
#include "base/containers/heap_array.h"
#include "base/memory/ptr_util.h"
#include "base/strings/cstring_view.h"
#include "base/strings/string_util.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#include "base/strings/utf_string_conversions.h"
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
#include <stdlib.h>
#endif
namespace base {
namespace {
class EnvironmentImpl : public Environment {
public:
std::optional<std::string> GetVar(cstring_view variable_name) override {
auto result = GetVarImpl(variable_name);
if (result.has_value()) {
return result;
}
// Some commonly used variable names are uppercase while others
// are lowercase, which is inconsistent. Let's try to be helpful
// and look for a variable name with the reverse case.
// I.e. HTTP_PROXY may be http_proxy for some users/systems.
char first_char = variable_name[0];
std::string alternate_case_var;
if (IsAsciiLower(first_char)) {
alternate_case_var = ToUpperASCII(variable_name);
} else if (IsAsciiUpper(first_char)) {
alternate_case_var = ToLowerASCII(variable_name);
} else {
return std::nullopt;
}
return GetVarImpl(alternate_case_var);
}
bool SetVar(cstring_view variable_name,
const std::string& new_value) override {
return SetVarImpl(variable_name, new_value);
}
bool UnSetVar(cstring_view variable_name) override {
return UnSetVarImpl(variable_name);
}
private:
std::optional<std::string> GetVarImpl(cstring_view variable_name) {
#if BUILDFLAG(IS_WIN)
std::wstring wide_name = UTF8ToWide(variable_name);
// Documented to be the maximum environment variable size in characters.
static constexpr size_t kMaxLength = 32767;
auto value = base::HeapArray<wchar_t>::Uninit(kMaxLength);
const DWORD value_length =
::GetEnvironmentVariable(wide_name.c_str(), value.data(), kMaxLength);
if (value_length == 0 || value_length >= kMaxLength) {
return std::nullopt; // Ignore errors and excessively large values.
}
return WideToUTF8(std::wstring_view(value.data(), value_length));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
const char* env_value = getenv(variable_name.c_str());
if (!env_value) {
return std::nullopt;
}
return std::string(env_value);
#endif
}
bool SetVarImpl(cstring_view variable_name, const std::string& new_value) {
#if BUILDFLAG(IS_WIN)
// On success, a nonzero value is returned.
return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(),
UTF8ToWide(new_value).c_str());
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
// On success, zero is returned.
return !setenv(variable_name.c_str(), new_value.c_str(), 1);
#endif
}
bool UnSetVarImpl(cstring_view variable_name) {
#if BUILDFLAG(IS_WIN)
// On success, a nonzero value is returned.
return !!SetEnvironmentVariable(UTF8ToWide(variable_name).c_str(), nullptr);
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
// On success, zero is returned.
return !unsetenv(variable_name.c_str());
#endif
}
};
} // namespace
Environment::~Environment() = default;
// static
std::unique_ptr<Environment> Environment::Create() {
return std::make_unique<EnvironmentImpl>();
}
bool Environment::HasVar(cstring_view variable_name) {
return GetVar(variable_name).has_value();
}
} // namespace base
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