Question

我使用的是Leadtools 17.5。如果我将Leadtools Dll静态链接到我的64位C ++应用程序，然后调用L_SetLicenseBuffer一切正常，返回值为零。但出于安全原因，最终产品不允许将这些DLL添加到System32文件夹中，也不允许更改系统路径，并且由于多个应用程序正在使用我希望将它们安装在一个共同的工具中文件夹（例如 C：\ Program Files \ Common Files \ LeadTools \ 17.5 ）并使用https://myactualdomain-my.sharepoint.com/_api/v2.0添加DLL搜索路径的路径。所以我决定在运行时动态加载DLL。所以我为这个函数创建了一个定义：

typedef L_INT (EXT_FUNCTION* TL_SetLicenseBuffer)(L_UCHAR* pLicenseBuffer, L_SSIZE_T nSize, L_TCHAR* pszDeveloperKey);
typedef L_BOOL (EXT_FUNCTION* TL_IsSupportLocked)(L_UINT uType);

然后

创建了一个像这样的函数指针：

TL_SetLicenseBuffer pfSetLicenseBuffer = NULL;
TL_IsSupportLocked pfIsSupportLocked = NULL;

然后添加DLL到DLL搜索路径的路径：

AddDllDirectory(LEAD_DLL_PATH);
AddDllDirectory(LEAD_FILTER_PATH);

并将DLL的默认目录搜索路径设置为用户定义：

SetDefaultDllDirectories(LOAD_LIBRARY_SEARCH_USER_DIRS);

然后加载DLL并获取我需要的函数的地址：

HINSTANCE hKrn = LoadLibrary(L"ltkrnx.dll");
pfSetLicenseBuffer = (TL_SetLicenseBuffer)GetProcAddress(hKrn, "L_SetLicenseBuffer");
pfIsSupportLocked  = (TL_IsSupportLocked)GetProcAddress(hKrn, "L_IsSupportLocked");

现在如果我使用与之前相同的参数的函数指针，函数将失败并返回-13，并且对{例如pfIsSupportLocked的任何后续调用都会显示nag对话框：

retCode = pfSetLicenseBuffer(pLicenseData, LicSize, pKeyStr); // retCode is -13
pfIsSupportLocked(L_SUPPORT_DOCUMENT); // Shows nag dialog

有谁知道如何解决这个问题？

谢谢你萨姆

Answer 1

您需要做的第一件事是检查调试器输出并确保您希望加载的DLL是通过验证路径加载的DLL。您的搜索路径中可能有多个版本的LTKRNX.DLL。我在这里测试了你的代码并返回了SUCCESS：

typedef L_INT (EXT_FUNCTION* TL_SetLicenseBuffer)(L_UCHAR* pLicenseBuffer, L_SSIZE_T nSize, L_TCHAR* pszDeveloperKey);
typedef L_BOOL (EXT_FUNCTION* TL_IsSupportLocked)(L_UINT uType);

HINSTANCE hKrn = LoadLibrary(L"ltkrnx.dll");
TL_SetLicenseBuffer pfSetLicenseBuffer = NULL;
TL_IsSupportLocked pfIsSupportLocked = NULL;

pfSetLicenseBuffer = (TL_SetLicenseBuffer)GetProcAddress(hKrn, "L_SetLicenseBuffer");
pfIsSupportLocked  = (TL_IsSupportLocked)GetProcAddress(hKrn, "L_IsSupportLocked");

L_INT retCode = pfSetLicenseBuffer(szLICAnsi, _countof(szLICAnsi), pKeyStr);
if(retCode == SUCCESS)
  bRet = pfIsSupportLocked(L_SUPPORT_DOCUMENT);
else
  printf("Problem!");

PaulMcKenzie建议的另一种方法是验证您对LoadLibrary的调用是否正常工作。如果您仍然无法弄清楚，可以通过support@leadtools.com联系我们的技术支持以帮助您解决此问题

Answer 2

我根本无法使动态加载工作，但我能够使用Delay loading来工作。
我要做的就是回到链接提取的.Lib文件到我的应用程序然后告诉编译器加载相关的DLL延迟，这让我有机会创建Notification Hooks到 __ pfnDliNotifyHook2 和 __ pfnDliFailureHook2 这样我可以使用LoadLibrary从正确的位置加载延迟加载的Dll。
但这只能解决问题的一半，因为其中一些Dll依赖于其他DLL，当我使用完整路径加载我想要的DLL时，它找不到辅助DLL（它与我正在加载的目录位于同一目录中），这将导致LoadLibrary失败。解决方案是跟踪这些依赖关系并预加载它们。我将包含一些代码来解决可能在以后遇到类似情况的任何人的问题。
P. S。 我正在使用 Embarcadero的C ++ Builder ，因此Strings，TStringList和Exception等某些对象可能不会正是每个人都熟悉的，但这个概念也适用于VC ++。

#include <map>

struct TDllDependency
{
    TStringList* Dependency;
    HMODULE hDll;

    __fastcall TDllDependency(void)
    {
        hDll = NULL;
        Dependency = new TStringList();
    }
    virtual __fastcall ~TDllDependency(void)
    {
        delete Dependency;
    }
};

class TDllModList : public std::map<System::String, TDllDependency>
{
public:
    void __fastcall CheckDependency(const System::String& aName);
};
//---------------------------------------------------------------------------
System::String __fastcall GetLtDllPath(void)
{
    wchar_t* pfPath = NULL;
    System::String dllPath;

    SHGetKnownFolderPath(FOLDERID_ProgramFilesCommon, KF_FLAG_DEFAULT, NULL, &pfPath);
    if (NULL != pfPath)
    {
        dllPath = IncludeTrailingBackslash(pfPath) + L"LeadTools\\17.5\\";
        ::CoTaskMemFree(pfPath);
    }
    return dllPath;
}
System::String mDllPath(GetLtDllPath());
TDllModList DllModList;
void __fastcall InitDllDepends()
{
    DllModList.clear();
#if defined(_WIN64)
    DllModList[L"ltimgefxx.dll"].Dependency->CommaText = L"ltdisx.dll,ltimgutlx.dll";
    DllModList[L"ltefxx.dll"].Dependency->CommaText = L"ltdisx.dll,ltimgutlx.dll";
    DllModList[L"ltimgcorx.dll"].Dependency->CommaText = L"ltdisx.dll,ltimgutlx.dll";
    DllModList[L"ltdlgimgefxx.dll"].Dependency->CommaText = L"ltdisx.dll,ltdlgkrnx.dll,ltdlgcomx.dll,ltdlgctrlx.dll,ltdlgutlx.dll,ltimgefxx.dll,ltimgsfxx.dll,ltimgcorx.dll,ltimgclrx.dll";
    DllModList[L"ltdlgutlx.dll"].Dependency->CommaText = L"ltdisx.dll,ltfilx.dll,ltdlgkrnx.dll,ltimgclrx.dll,ltimgcorx.dll,ltimgefxx.dll,ltimgsfxx.dll";
    DllModList[L"ltdlgctrlx.dll"].Dependency->CommaText = L"ltdlgutlx.dll,ltdlgkrnx.dll,ltdisx.dll,ltfilx.dll,ltimgefxx.dll";
    DllModList[L"ltdlgcomx.dll"].Dependency->CommaText = L"ltdlgkrnx.dll,ltdlgctrlx.dll,ltdlgutlx.dll";
#elif defined(__WIN32__)
    DllModList[L"ltimgefxu.dll"].Dependency->CommaText = L"ltdisu.dll,ltimgutlu.dll";
    DllModList[L"ltefxu.dll"].Dependency->CommaText = L"ltdisu.dll,ltimgutlu.dll";
    DllModList[L"ltimgcoru.dll"].Dependency->CommaText = L"ltdisu.dll,ltimgutlu.dll";
    DllModList[L"ltdlgimgefxu.dll"].Dependency->CommaText = L"ltdisu.dll,ltdlgkrnu.dll,ltdlgcomu.dll,ltdlgctrlu.dll,ltdlgutlu.dll,ltimgefxu.dll,ltimgsfxu.dll,ltimgcoru.dll,ltimgclru.dll";
    DllModList[L"ltdlgutlu.dll"].Dependency->CommaText = L"ltdisu.dll,ltfilu.dll,ltdlgkrnu.dll,ltimgclru.dll,ltimgcoru.dll,ltimgefxu.dll,ltimgsfxu.dll";
    DllModList[L"ltdlgctrlu.dll"].Dependency->CommaText = L"ltdlgutlu.dll,ltdlgkrnu.dll,ltdisu.dll,ltfilu.dll,ltimgefxu.dll";
    DllModList[L"ltdlgcomu.dll"].Dependency->CommaText = L"ltdlgkrnu.dll,ltdlgctrlu.dll,ltdlgutlu.dll";
#endif
};
HMODULE SafeLoadLeadDll(const System::String tName)
{
    System::String tPath;
    HMODULE retVal = NULL;

    DllModList.CheckDependency(tName);
    tPath = mDllPath + tName;
    if(FileExists(tPath))
        retVal = ::LoadLibrary(tPath.c_str());
    return retVal;
}
FARPROC WINAPI MyDliNotifyHook(unsigned dliNotify, PDelayLoadInfo pdli)
{
    FARPROC retVal = NULL;
    System::String tStr(pdli->szDll);

    tStr = tStr.LowerCase();
    if(dliNotePreLoadLibrary == dliNotify)
    {
        TDllModList::iterator i = DllModList.find(tStr);

        if(DllModList.end() == i)
        {
            retVal = (FARPROC)SafeLoadLeadDll(tStr);
            DllModList[tStr].hDll = (HMODULE)retVal;
        }
        else if(NULL == i->second.hDll)
        {
            i->second.hDll = SafeLoadLeadDll(tStr);
            retVal = (FARPROC)i->second.hDll;
        }
        else
            retVal = (FARPROC)i->second.hDll;
    }
    else if(dliFailLoadLib == dliNotify)
    {
        tStr = L"Compleatly falied to load " + tStr;
        ::OutputDebugString(tStr.c_str());
    }
    return retVal;
}

FARPROC WINAPI MyDliFailureHook(unsigned dliNotify, PDelayLoadInfo pdli)
{
    FARPROC retVal = NULL;
    if(dliNotePreLoadLibrary == dliNotify)
    {
        System::String tMsg = pdli->szDll;

        tMsg = L"Failed to load \"" + tMsg + L"\".\n" + SysErrorMessage(::GetLastError());
        throw Exception(tMsg);
    }
    return retVal;
}

extern "C" PfnDliHook __pfnDliNotifyHook2 = MyDliNotifyHook;
extern "C" PfnDliHook __pfnDliFailureHook2 = MyDliFailureHook;
void __fastcall TDllModList::CheckDependency(const System::String& aName)
{
    TDllModList::iterator i = find(aName);

    if(end() != i)
    {
        int len = i->second.Dependency->Count;
        int j;
        System::String tPath;

        for(j = 0; j < len; j++)
        {
            if(end() == find(i->second.Dependency->Strings[j]))
            {
                CheckDependency(i->second.Dependency->Strings[j]);
                tPath = mDllPath + i->second.Dependency->Strings[j];
                (*this)[i->second.Dependency->Strings[j]].hDll = ::LoadLibrary(tPath.c_str());
            }
        }
    }
}
//---------------------------------------------------------------------------

当然InitDllDepends();应该在WinMain的开头调用，以便正确设置。

动态加载Leadtools DLL

2 个答案: