Question

我创建了一个用于Unity5 C＃程序的C ++ .dll库。

但是，当我从Unity编辑器运行程序并尝试调用smCopy时，Unity会崩溃并尝试发送错误报告;相反，我追踪错误是从smCopy发生的访问冲突错误。

.dll库允许我连接到服务器并通过此函数将数据复制到给定参数中：

C++:
void DLL_API smCopy(const VOID *dest, SIZE_T len)
{
    CopyMemory((PVOID)(dest), (PVOID)(mapBuffer), len);
}

在我的Unity脚本中，我导入了函数：

C#:
[DllImport(DLL_NAME, EntryPoint = "smCopy")] 
private static extern void smCopyData(IntPtr dest, IntPtr len);

最后称呼它：

C#:
{
 //  create IntPtr for message
    IntPtr msg_intptr = new IntPtr();

    smCopyData(msg_intptr, (IntPtr)Marshal.SizeOf(typeof(smMsg)));

    //  create actual data struct
        // smMsg is a struct referenced in both .dll & Unity script
    smMsg data_msg = new smMsg();

    //  Set POINTER data to struct
    Marshal.PtrToStructure(msg_intptr, data_msg);
}

我调试并跟踪了smCopyData发生的错误，日志中发现以下错误：

  `VCRUNTIME140D.dll caused an Access Violation (0xc0000005) in module VCRUNTIME140D.dll at 0033:b4761c89.`

.dll可与其他功能配合使用，除了出现此错误外，我还能成功连接到服务器。

现在我不知道接下来会做什么，因为我需要这个函数将数据从服务器复制到结构中。

我怎样才能将内存从服务器（mapBuffer）复制到C＃的参数变量中？

Reference to Marshal & IntPtr

Editor.log Stack Trace

0x00007FFBB70A1C89 (VCRUNTIME140D) memcpy
0x00007FFBB72819D9 (SharedMemoryClientDLL) [l:\projects\google\chapstick\software\working\abner\misc proj\vs\sharedmemoryclientdll\sharedmemoryclientdll\smclibrary.cpp:151] smCopy 
0x0000000012B65B29 (Mono JIT Code) (wrapper managed-to-native) SMCScript:smCopyData (intptr,intptr)
0x0000000012B65793 (Mono JIT Code) [L:\Projects\Google\chapstick\Software\Working\Abner\Misc Proj\Unity\ChapstickProject\Assets\Scripts\SMCScript.cs:202] SMCScript:GetData () 
0x0000000012B62CA3 (Mono JIT Code) [L:\Projects\Google\chapstick\Software\Working\Abner\Misc Proj\Unity\ChapstickProject\Assets\Scripts\SMCScript.cs:176] SMCScript:CheckForEvent () 
0x0000000010B69232 (Mono JIT Code) [L:\Projects\Google\chapstick\Software\Working\Abner\Misc Proj\Unity\ChapstickProject\Assets\Scripts\SMCScript.cs:150] SMCScript:Update () 
0x00000000007D68E2 (Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void__this__ (object,intptr,intptr,intptr)
0x00007FFB9B5F41BF (mono) [c:\buildslave\mono-runtime-and-classlibs\build\mono\mini\mini.c:4937] mono_jit_runtime_invoke 
0x00007FFB9B548435 (mono) [c:\buildslave\mono-runtime-and-classlibs\build\mono\metadata\object.c:2623] mono_runtime_invoke 
0x000000014033E20F (Unity) scripting_method_invoke

Answer 1

您需要分配一个缓冲区并将其指针传递给该函数。您只是传递一个空指针，因此cpp函数正在尝试写入地址0，这会导致访问冲突异常。

var len = Marshal.SizeOf(typeof(smMsg));
IntPtr msg_intptr = Marshal.AllocHGlobal(len);
try {
    // call the function, convert output to struct, etc...
}
finally {
    Marshal.FreeHGlobal(msg_intptr);
}

从dll使用CopyMemory并抛出访问冲突错误

1 个答案: