c++ - 从C++ dll调用Go dll

Question

我在Go中使用导出的函数创建了该dll，当我使用rundll32或使用loadlbraryA从c++可执行文件调用它时，该函数运行良好。但是我从c++ dll调用时遇到错误，我尝试读取GetLastError()并显示cannot find the module you are calling。我尝试了所有可能的方法来提供loadlibraryA的完整路径，但是会发生相同的错误，并且每次DLL的句柄都为空。另外，我检查了Go DLL，并正确导出了Test函数。
简而言之，它在调用Test()时起作用:

来自rundll32

来自c++ main()和loadlibrary

并且在Test()中不起作用:

来自C++ DllMain()和loadlibrary的

从c++ DllMain()和loadlibrary直接从kernel32.dll调用

来自c++ DllMain()和在DllMain()中创建的ThreadFunction

资料夹结构

ProjectFolder
-- main.go
-- dllmain.h
-- dllmain.go

建立

go build -buildmode=c-shared -o my-go-library.dll main.go

调用示例dll

rundll32 my-go-library.dll Test

工作来源
main.go:

package main

import "C"

import (
    "syscall"
    "time"
    "unsafe"
)

//export Test
func Test() {
    MessageBoxPlain("TestMsgbox","Test")
    main()
}

//export OnProcessAttach
func OnProcessAttach() {
    MessageBoxPlain("OnAttachMsgbox","OnAttach")
    Test()
}

// MessageBox of Win32 API.
func MessageBox(hwnd uintptr, caption, title string, flags uint) int {
    ret, _, _ := syscall.NewLazyDLL("user32.dll").NewProc("MessageBoxW").Call(
        uintptr(hwnd),
        uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(caption))),
        uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(title))),
        uintptr(flags))

    return int(ret)
}

// MessageBoxPlain of Win32 API.
func MessageBoxPlain(title, caption string) int {
    const (
        NULL  = 0
        MB_OK = 0
    )
    return MessageBox(NULL, caption, title, MB_OK)
}

func main() {}

dllmain.h:

#include <windows.h>

void OnProcessAttach(HINSTANCE, DWORD, LPVOID);

typedef struct {
    HINSTANCE hinstDLL;  // handle to DLL module
    DWORD fdwReason;     // reason for calling function // reserved
    LPVOID lpReserved;   // reserved
} MyThreadParams;

DWORD WINAPI MyThreadFunction(LPVOID lpParam) {
    MyThreadParams params = *((MyThreadParams*)lpParam);
    OnProcessAttach(params.hinstDLL, params.fdwReason, params.lpReserved);
    free(lpParam);
    return 0;
}

BOOL WINAPI DllMain(
    HINSTANCE _hinstDLL,  // handle to DLL module
    DWORD _fdwReason,     // reason for calling function
    LPVOID _lpReserved)   // reserved
{
    switch (_fdwReason) {
    case DLL_PROCESS_ATTACH:
            // Initialize once for each new process.
        // Return FALSE to fail DLL load.
        {
            MyThreadParams* lpThrdParam = (MyThreadParams*)malloc(sizeof(MyThreadParams));
            lpThrdParam->hinstDLL = _hinstDLL;
            lpThrdParam->fdwReason = _fdwReason;
            lpThrdParam->lpReserved = _lpReserved;
            HANDLE hThread = CreateThread(NULL, 0, MyThreadFunction, lpThrdParam, 0, NULL);
            // CreateThread() because otherwise DllMain() is highly likely to deadlock.
        }
        break;
    case DLL_PROCESS_DETACH:
        // Perform any necessary cleanup.
        break;
    case DLL_THREAD_DETACH:
        // Do thread-specific cleanup.
        break;
    case DLL_THREAD_ATTACH:
        // Do thread-specific initialization.
        break;
    }
    return TRUE; // Successful.
}

dllmain.go:

package main

//#include "dllmain.h"
import "C"

C++ DLL
现在，从 Test调用 my-go-library.dll的c++ dll源:

#include "pch.h"
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <winternl.h>
#include <malloc.h>
#include <intrin.h>
#include <Windows.h>
#include <winternl.h>
#include <malloc.h>
#include <ostream>
#include <iostream>
#include <string>

using namespace std;

typedef int(__stdcall* TestFromGo)();

void Error()
{
    wchar_t err[256];
    memset(err, 0, 256);
    FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), err, 255, NULL);
    int msgboxID = MessageBoxW(NULL,err,(LPCWSTR)L"Error",MB_OK);
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
    MessageBoxA(0, "The C++ DLL", "title", 0);
    
    HINSTANCE hGetProcIDDLL = LoadLibraryA("C:\\User\\.....path to go dll.....\\my-go-library.dll");
    if (!hGetProcIDDLL) {
        Error();
        MessageBoxA(0, "could not load the dynamic library", "Test", 0);
    }
    TestFromGo TestFunction = (TestFromGo)GetProcAddress(hGetProcIDDLL, "Test");
    if (!TestFunction) {
        MessageBoxA(0, "could not locate the function", "Test", 0);
    }

    TestFromGo();
}

extern "C" __declspec(dllexport) void jojo()
{
    DllMain(0, 1, 0);
}

调用C++ dll
现在，这个应该先调用 jojo，再调用 DllMain，再调用 my-go-library.dll和 Test

rundll32 theCiplasplas.dll jojo

Answer 1

我帮不上Golang。但是您的DllMain中存在问题。 DllMain仅允许有限的一组API函数。
Dynamic-Link Library Best Practices明确指出您不应在DllMain中创建线程:

You should never perform the following tasks from within DllMain:

• Call CreateThread. Creating a thread can work if you do not synchronize with other threads, but it is risky.
• Call LoadLibrary or LoadLibraryEx (either directly or indirectly). This can cause a deadlock or a crash

因此，当您使用rundll32时，它可能会起作用；如果以其他方式加载DLL，则它可能会不起作用。
编辑:添加了有关LoadLibrary的摘录