跟Google学写代码--Chromium/base--windows_version源码学习及应用

柔情只为你懂 2022-07-14 13:49 62阅读 0赞

Chromium是一个伟大的、庞大的开源工程，很多值得我们学习的地方。  
前面写道：  
《[跟Google学写代码–Chromium/base–stl\_util源码学习及应用][Google_Chromium_base_stl_util]》

今天与大家分享的就是Chromium下base中的windows\_version，对于你的win32应用程序一定会有很多的帮助。

**1 定义version枚举**

enum Version {
      VERSION_PRE_XP = 0,  // Not supported.
      VERSION_XP,
      VERSION_SERVER_2003, // Also includes XP Pro x64 and Server 2003 R2.
      VERSION_VISTA,       // Also includes Windows Server 2008.
      VERSION_WIN7,        // Also includes Windows Server 2008 R2.
      VERSION_WIN8,        // Also includes Windows Server 2012.
      VERSION_WIN8_1,      // Code named Windows Blue
      VERSION_WIN_LAST,    // Indicates error condition.
    };

enum VersionType {
      SUITE_HOME,
      SUITE_PROFESSIONAL,
      SUITE_SERVER,
      SUITE_LAST,
    };

**2 定义 OSInfo类**  
a. 通过BASE\_EXPORT定义为导出类  
b. 将OSInfo()和 ~OSInfo()声明为私有，即我们要的单例模式

class BASE_EXPORT OSInfo {
     public:
      struct VersionNumber {
        int major;
        int minor;
        int build;
      };
    
      struct ServicePack {
        int major;
        int minor;
      };
    
      enum WindowsArchitecture {
        X86_ARCHITECTURE,
        X64_ARCHITECTURE,
        IA64_ARCHITECTURE,
        OTHER_ARCHITECTURE,
      };
    
      enum WOW64Status {
        WOW64_DISABLED,
        WOW64_ENABLED,
        WOW64_UNKNOWN,
      };
    
      static OSInfo* GetInstance();
    
      Version version() const { return version_; }
      VersionNumber version_number() const { return version_number_; }
      VersionType version_type() const { return version_type_; }
      ServicePack service_pack() const { return service_pack_; }
      WindowsArchitecture architecture() const { return architecture_; }
      int processors() const { return processors_; }
      size_t allocation_granularity() const { return allocation_granularity_; }
      WOW64Status wow64_status() const { return wow64_status_; }
      std::string processor_model_name();
    
      static WOW64Status GetWOW64StatusForProcess(HANDLE process_handle);
    
     private:
      OSInfo();
      ~OSInfo();
    
      Version version_;
      VersionNumber version_number_;
      VersionType version_type_;
      ServicePack service_pack_;
      WindowsArchitecture architecture_;
      int processors_;
      size_t allocation_granularity_;
      WOW64Status wow64_status_;
      std::string processor_model_name_;
    
      DISALLOW_COPY_AND_ASSIGN(OSInfo);
    };
    
    // Because this is by far the most commonly-requested value from the above
    // singleton, we add a global-scope accessor here as syntactic sugar.
    BASE_EXPORT Version GetVersion();
    
    }  // namespace win
    }  // namespace base

**3 GetInstance()的实现**  
这里用到了InterlockedCompareExchangePointer：  
Provides compiler intrinsic support for the Win32 Platform SDK InterlockedCompareExchangePointer function.

OSInfo* OSInfo::GetInstance() {
      static OSInfo* info;
      if (!info) {
        OSInfo* new_info = new OSInfo();
        if (InterlockedCompareExchangePointer(
            reinterpret_cast<PVOID*>(&info), new_info, NULL)) {
          delete new_info;
        }
      }
      return info;
    }

这里补充一下，delete new\_info后，最好把new\_info置为nullptr。

**4 获取WOW64状态的实现**  
最主要的是这行：  
GetProcAddress(GetModuleHandle(L”kernel32.dll”), “IsWow64Process”));

可以通过加载Kernel32来动态判断 当前操作系统32bit还是64bit。

OSInfo::WOW64Status OSInfo::GetWOW64StatusForProcess(HANDLE process_handle) {
      typedef BOOL (WINAPI* IsWow64ProcessFunc)(HANDLE, PBOOL);
      IsWow64ProcessFunc is_wow64_process = reinterpret_cast<IsWow64ProcessFunc>(
          GetProcAddress(GetModuleHandle(L"kernel32.dll"), "IsWow64Process"));
      if (!is_wow64_process)
        return WOW64_DISABLED;
      BOOL is_wow64 = FALSE;
      if (!(*is_wow64_process)(process_handle, &is_wow64))
        return WOW64_UNKNOWN;
      return is_wow64 ? WOW64_ENABLED : WOW64_DISABLED;
    }

**应用：**  
简单的使用：

int main(int argc, char* argv[]) {
    
      int version = base::win::OSInfo::GetInstance()->version();
      std::cout << "VERSION_PRE_XP = 0," << std::endl;
      std::cout << "VERSION_SERVER_2003 = 1," << std::endl;
      std::cout << "VERSION_VISTA = 2," << std::endl;
      std::cout << "VERSION_WIN7 = 3," << std::endl;
      std::cout << "VERSION_WIN8 = 4," << std::endl;
      std::cout << "VERSION_WIN8_1 = 5," << std::endl;
      std::cout << "VERSION_WIN_LAST = 6," << std::endl;
      std::cout << "My Windows Version is: " << version << std::endl << std::endl;
    
      std::string processor_model_name = base::win::OSInfo::GetInstance()->processor_model_name();
      std::cout << "My Processor Model Name is: " << processor_model_name << std::endl << std::endl;
    
      int wow64_status = base::win::OSInfo::GetInstance()->wow64_status();
      std::cout << "WOW64_DISABLED = 0," << std::endl;
      std::cout << "WOW64_ENABLED = 1," << std::endl;
      std::cout << "WOW64_UNKNOWN = 2," << std::endl;
      std::cout << "My wow64_status is: " << wow64_status << std::endl << std::endl;
    
    
    
    
      base::win::OSInfo::VersionNumber version_number = base::win::OSInfo::GetInstance()->version_number();
      std::cout << "My Version Number: " << std::endl;
      std::cout << " major: " << version_number.major << std::endl;
      std::cout << " minor: " << version_number.minor << std::endl;
      std::cout << " build: " << version_number.build << std::endl;
    
      system("pause");
      return 0;
    }

输出结果：

VERSION_PRE_XP = 0,
    VERSION_SERVER_2003 = 1,
    VERSION_VISTA = 2,
    VERSION_WIN7 = 3,
    VERSION_WIN8 = 4,
    VERSION_WIN8_1 = 5,
    VERSION_WIN_LAST = 6,
    My Windows Version is: 5
    
    My Processor Model Name is: Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz
    
    WOW64_DISABLED = 0,
    WOW64_ENABLED = 1,
    WOW64_UNKNOWN = 2,
    My wow64_status is: 1
    
    My Version Number:
     major: 6
     minor: 2
     build: 9200

**插曲** 一个坑儿：  
![这里写图片描述][SouthEast]

一个VS中有好几个工程，在运行我们想要运行的项目的时候，出现上图中的错误。

如果你不够细心，你就以为是库的版本不对，比如库是64位，而你运行的是32位程序。。。。。。  
但是你看编译库的工程也是32位的，这时候就有点发蒙。。。。。  
蓦然回首，你没有把想要运行的程序设置为启动项，而且把那个库的工程设置为了启动项。

[Google_Chromium_base_stl_util]: http://blog.csdn.net/wangshubo1989/article/details/53558617
[SouthEast]: /images/20220714/12ce1aa1a38749eabd5e3b315cff5ae4.png