[WinDbg] Remote Kernel Debug over Network cable

WinDbg 不僅可以用來 Debug User mode 的 process，還可以用來 Debug Kernel mode 的 Windows，基本上使用的方式必須有兩台電腦，或是 VM ，因為 你如果要做 local 的 Kernel Debug 的話，中斷點 hit 到的話，整台電腦應該就會 block 住，但是 local Kernel Debug 無法這麼做的。

既然要透過 remote 的方式來做 Kernel Debug，所以 Windows 提供了不少方法讓你連線到另一台電腦，包括 Serial cable (COM)、1394 cable、Network cable、USB cable …等等，其中 Serial cable & 1394 使用上的限制比較少，support 的平台也比較多，Network cable 與 USB cable 對硬體與平台的限制都不少，所以要確認你的硬體平台有支援的話，才可以透過 Network cable, USB cable 來做 debug。

[C/C++] 在 Windows 上 Build static libCURL library

libcurl 是個跨平台的 library ，支援非常多的 protocol，重點還是 open source!
以下就是簡單的 build 出一個 libcurl 的 static library 教學

1. 首先 download libcurl 的 source code 壓縮檔

libCURL download page

2. 在 command line 準備好 VC 的 compile 環境

"{VC Install Path}\VC\vcvarsall.bat" x86

設置完環境後，才能執行 namke

3. 開始 build libcurl

cd {libcurl extract dir}\winbuild
nmake /f Makefile.vc mode=static DEBUG=yes MAXHINE=x86

mode = static 也可以是 dll ，只是我們目標是 static library
build 完後，可以在 {libcurl extract dir}\builds 找到 lib 還有 header 檔

其他參數說明

• VC=<6,7,8,9,10>
• VC版本(不一定要填)
• WITH_SSL=<dll or static>
• 使用OpenSSL詳細參閱，會有 License 問題
• ENABLE_WINSSL=<yes or no>
• Enable native 的 Windows SSL 功能
• 記得，如果要 enable 的話，ENABLE_SSPI一定也要 enable !
• GEN_PDB=<yes or no>
• 產生 .pdb 檔
• DEBUG=<yes or no>
• Debug or Release mode
• MACHINE=<x86 or x64>
• Target architecture
• RTLIBCFG
• 不指定就是 default，compile 參數會加上 /MD or /MDd (Multi-threaded)
• =static，compile 參數會加上 /MT or /MTd (Multi-threaded DLL)

4. VC project setting 設置

在 Project Property | Linker | General | Additional Library Directories 
加上放有 build 出的 .lib 的目錄

在 Project Property | Linker | Input | Additional Dependencies 
加上 libcurl_a.lib or libcurl_a_debug.lib

在 Project Property | C/C++ | Preprocessor 
加上 CURL_STATICLIB 這個 macro 才行
否則會出現類似這樣的錯誤訊息：

1>A.obj : error LNK2019: unresolved external symbol __imp__curl_global_init referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_slist_append referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_slist_free_all referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_strerror referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_init referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_setopt referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_perform referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_cleanup referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)

[Win32] 在C/C++中偵測精準的程式時間(Performance Time)

在Windows底下，要偵測精準的Perfromance Time，可以透過QueryPerformanceFrequency() & QueryPerformanceCounter() 來取得。

由於取得的時間存在LARGE_INTEGER的structure，要取出來計算所花費的時間需要多點程式碼才行。這邊寫了一個簡單的Wrapper Class，讓這個AutoQueryPerformance的instance life-time結束後，自行dump出所花費的時間。

AutoQueryPerformance

#include "windows.h"

// Auto dump the life-time of AutoQueryPerformance
// Ex:
// {
//     AutoQueryPerformance autoQuery("Test", true);
//     ...
// } // it will dump message when @autoQuery destroy
class AutoQueryPerformance
{
public:
    AutoQueryPerformance(const char* info, INT loop_count=1, BOOL autoDump=TRUE)
        : m_count_time(0), m_loop_count(loop_count), m_auto(autoDump)
    {
        m_info = info;
        ::ZeroMemory(&m_cpu_freq, sizeof(LARGE_INTEGER));
        ::QueryPerformanceFrequency(&m_cpu_freq);

        if( autoDump )
            begin();
    }
    ~AutoQueryPerformance()
    {
        pause();
        if( autoDump )
            printf("[AutoQueryPerformance][%s] spend time=%.4f", m_info.c_str(), getTime());
    }
    inline void begin()
    {
        ::ZeroMemory(&m_start_clock, sizeof(LARGE_INTEGER));;
        ::QueryPerformanceCounter(&m_start_clock);
    }
    inline void pause()
    {
        ::ZeroMemory(&m_cur_clock, sizeof(LARGE_INTEGER));
        ::QueryPerformanceCounter(&m_cur_clock);
        m_count_time += m_cur_clock.QuadPart-m_start_clock.QuadPart;
    }
    inline void stop()
    {
        pause();
        m_count_time = 0;
    }
    inline float getTime()
    {
        return (m_count_time/(float)m_cpu_freq.QuadPart) / m_loop_count;
    }
private:
    LARGE_INTEGER m_cpu_freq;
    LARGE_INTEGER m_start_clock;
    LARGE_INTEGER m_cur_clock;
    LONGLONG      m_count_time;
    INT           m_loop_count;//for for-loop to calculate correct average time
    std::string   m_info;
    BOOL          m_auto;
};
#define AUTO_QUERY_PERFORMANCE(x) AutoQueryPerformance __at_qp = AutoQueryPerformance(x);

使用範例

void TestingTotalTime(int loop_count)
{
    AutoQueryPerformance ap("TestingTotalTime");
    int sum = 0;
    for(int i=0 ; i<loop_count; i++)
       sum += i;
}

void TestingSingleTime(int loop_count)
{
    AutoQueryPerformance ap("TestingSingleTime", loop_count);
    for(int i=0 ; i<loop_count; i++)
       //HeavyFunction call here;
}

Reference

• MSDN - QueryPerformanceFrequency
• MSDN - QueryPerformanceCounter

[Win32/COM] Use COM DLL without registered

依照Windows COM元件的使用方法，應該要將COM DLL註冊後，即可在程式中，以CoCreateInstance()帶入CLSID、IID就可以將該DLL自動load起來，創建該class的instance了。

但是在開發時，實際上總是沒這麼美好，註冊DLL其實是很麻煩的，新舊相容性，開發中的版本等等的問題，而走manifest其實可以避開註冊這條路，但是今天我需要寫一個COM module讓別人使用，而這個COM module在AP裡是走manifest的，所以不會被註冊，連帶的module會用到其他的Library也不走註冊這條路，而因為一些其他的原因，也不能將此Library寫入manifest裡，只能尋求其他途徑了。

由於COM的DLL都會link到一些基本的COM Library，所以是有一些export的API可以繞過註冊來create COM instance的，直接參考以下的Sample Code吧。

// {599D2F5F-BA8D-4009-941C-A5393EBD5C58}
DEFINE_GUID(CLSID_MyCOM, 
0x599d2f5f, 0xba8d, 0x4009, 0x94, 0x1c, 0xa5, 0x39, 0x3e, 0xbd, 0x5c, 0x58);

// {4C452CB2-469C-4236-AE5C-F48A28EC0870}
DEFINE_GUID(IID_IMyCOM, 
0x4c452cb2, 0x469c, 0x4236, 0xae, 0x5c, 0xf4, 0x8a, 0x28, 0xec, 0x8, 0x70);

HRESULT CreateInstance(IMyCOM** pMyCom)
{
    HMODULE hDll = LoadLibrary("MY_COM.dll");//Need refine by your self
    if(hDll)
    {
        //////////////////////////////////////////////////////////////////////////
        // Initial COM instance without register
        //   Try to load COM DLL directly, and call DllGetClassObject to get IID_IClassFactory
        //   And Create COM instance by IID_IClassFactory
        // -----------------------------------------------------------------------
        //   HRESULT hr = CoCreateInstance(CLSID_MyCOM, 
        //                                 NULL, 
        //                                 CLSCTX_INPROC_SERVER, 
        //                                 IID_IMyCOM, 
        //                                 (PVOID*)&pMyCom);
        //////////////////////////////////////////////////////////////////////////
        CComPtr<IClassFactory> spFactory;

        // Get address of DllGetClassObject exported method
        PDLLGETCLSOBJ pDllGetCLSObj = (PDLLGETCLSOBJ)GetProcAddress(hDll, "DllGetClassObject");

        // Call DllGetClassObject and get the proper IClassFactory interface
        HRESULT hr = pDllGetCLSObj(CLSID_MyCOM, IID_IClassFactory, reinterpret_cast<PVOID*>(&spFactory));
        if( FAILED(hr) )
        {
            printf(__FUNCTION__" [Err] Can't get spFactory hr=%X", hr);
            return E_FAIL;
        }

        // Create an instance of IMyCOM
        hr = spFactory->CreateInstance(NULL, IID_IMyCOM, (PVOID*)pMyCom);
        if( FAILED(hr) )
        {
            printf(__FUNCTION__" [Err] Init IMyCOM Fail! hr=%X", hr);
            return E_FAIL;
        }
    }
    else
    {
        return E_FAIL;
    }
    return S_OK;
}

Reference:

• StackOverflow - Windows/C++: how to use a COM dll which is not registered

[C/C++] 研究long long * float overflow 可能導致的誤差

最近看bug看到一個奇怪的現象，在64bit的AP執行時，long long * float會有誤差出現，但是32bit的AP卻沒有這樣子的問題出現，直覺上不是應該32bit的AP比較會有問題嗎!?

先來看一下 long long 跟 float ，long long的size是8個byte，float的size是4個byte
long long * float，compiler會將結果存到float的temp變數裡，此時誤差就可能會出現了，但是這個誤差是「有條件」地出現，並不是任何long long的數字乘上float都會產生誤差的

以一個簡單的程式來驗證是否會產生誤差

bool check_longlong(long long v1)
{
    float f = 1.0f;
    long long v2 = long long( v1 * f );
    printf("ori value=%lld, new value=%lld, ori==new=%d", v1, v2, v1==v2);
    return v1==v2;
}

int _tmain(int argc, _TCHAR* argv[])
{
    check_longlong(0xF0000000000);//true - OK
    check_longlong(0x0FFFFFFFFFF);//false - Error!
    check_longlong(0x0FFFFFF);//true - OK
    check_longlong(0x1FFFFFF);//false - Error!
    return 0;
}

[C/C++] 取得LIB目前的DLL module path

如果寫了一個LIB or Cpp檔，讓多個DLL module include使用，該如果拿到目前DLL的module path?

GetModuleFileName() 參數hModule傳NULL的話，只能知道執行檔exe的路徑
要想知道自己在哪個DLL module的話，必須埋一些code才行

EXTERN_C IMAGE_DOS_HEADER __ImageBase
//...
WCHAR dll_path[MAX_PATH] = {0};
GetModuleFileNameW((HINSTANCE)&__ImageBase, dll_path, _MAX_PATH);

Reference :

• StackOverflow - Get Dll path at runtime
• MSDN - GetModuleFileName()

[Win32] Save Bitmap

Save Gdiplus::Bitmap

• MSDN - Bitmap
• MSDN - Image::Save()

HRESULT GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
    /*
    format support : 
        "image/png"
        "image/bmp"
        "image/gif"
        "image/jpeg"
        "image/tiff"
    */
    UINT  num  = 0;  // number of image encoders
    UINT  size = 0;  // size of the image encoder array in bytes

    GetImageEncodersSize(&num, &size);
    if(size == 0)
        return E_FAIL;  // Failure

    ImageCodecInfo* pImageCodecInfo = NULL;
    pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
    if(pImageCodecInfo == NULL)
        return E_FAIL;  // Failure
    GetImageEncoders(num, size, pImageCodecInfo);
    for(UINT j = 0; j < num; ++j)
    {
        if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
        {
            *pClsid = pImageCodecInfo[j].Clsid;
            free(pImageCodecInfo);
            return S_OK;  // Success
        }
    }
    free(pImageCodecInfo);
    return E_FAIL;
}

void SaveBitmap(Bitmap* bitmap)
{
    // Get the CLSID of the JPEG encoder.
    CLSID clsid;
    GetEncoderClsid(L"image/jpeg", &clsid);
    
    bitmap.Save(L"C:\\test.jpg", &clsid, NULL);
}

[Windows] Local time 轉 UTC

Window提供了 API 可以轉換時間的時區。

• TzSpecificLocalTimeToSystemTime：Local time -> UTC
• SystemTimeToTzSpecificLocalTime ：UTC -> Local time

第一個參數可指定 TIME_ZONE_INFORMATION，如果傳進 NULL 的話，即代表目前系統使用的Time Zone。

SYSTEMTIME ConvertLocalTime2UTC(UINT year, UINT month, UINT day, UINT hour, UINT minute, UINT second)
{
    SYSTEMTIME local, utc;
    ZeroMemory(&local, sizeof(local));
    local.wYear   = year;
    local.wMonth  = month;
    local.wDay    = day;
    local.wHour   = hour;
    local.wMinute = minute;
    local.wSecond = second;
    TzSpecificLocalTimeToSystemTime( NULL, &local, &utc );
    printf("UTC Time  =%d/%d/%d %d:%d:%d\n", utc.wYear, utc.wMonth, utc.wDay, utc.wHour, utc.wMinute, utc.wSecond);
    printf("Local Time=%d/%d/%d %d:%d:%d\n", local.wYear, local.wMonth, local.wDay, local.wHour, local.wMinute, local.wSecond);
    return utc;
}

SYSTEMTIME ConvertUTC2LocalTime(UINT year, UINT month, UINT day, UINT hour, UINT minute, UINT second)
{
    SYSTEMTIME local, utc;
    ZeroMemory(&utc, sizeof(utc));
    utc.wYear   = year;
    utc.wMonth  = month;
    utc.wDay    = day;
    utc.wHour   = hour;
    utc.wMinute = minute;
    utc.wSecond = second;
    SystemTimeToTzSpecificLocalTime( NULL, &utc, &local );
    printf("UTC Time  =%d/%d/%d %d:%d:%d\n", utc.wYear, utc.wMonth, utc.wDay, utc.wHour, utc.wMinute, utc.wSecond);
    printf("Local Time=%d/%d/%d %d:%d:%d\n", local.wYear, local.wMonth, local.wDay, local.wHour, local.wMinute, local.wSecond);
    return local;
}

Reference：

• TzSpecificLocalTimeToSystemTime Function
• SystemTimeToTzSpecificLocalTime Function

[Win32 API] String Conversion

在Windows底下做字串轉換其實還滿簡單的，在MFC的Library裡，提供了一些簡單的Marco可以用，就可以針對wstring, string, CComBSTR, BSTR之間做轉換了。需 Include AtlBase.h, AtlConv.h

以下是 ATL7.0 版 Marco、Class的命名規則

CSourceType2[C]DestinationType[EX]

以下是 ATL3.0 舊版 Marco的命名規則

SourceType2[C]DestinationType[EX]