暴露 C++ API 到 C#

发布于 2024-08-28 09:45:38 字数 1500 浏览 7 评论 0原文

因此，我拥有的是 *.dll 中包含的 C++ API，并且我想使用 C# 应用程序来调用 API 中的方法。

到目前为止，我已经创建了一个 C++/CLR 项目，其中包含本机 C++ API，并设法创建了一个类似于以下内容的“桥”类：

// ManagedBridge.h
#include <CoreAPI.h>
using namespace __CORE_API;

namespace ManagedAPIWrapper
{
    public ref class Bridge
    {
        public:
            int             bridge_test(void);
            int             bridge_test2(api_struct* temp);
    }
}

。

// ManagedBridge.cpp
#include <ManagedBridge.h>

int Bridge::bridge_test(void)
{
    return test();
}

int Bridge::bridge_test2(api_struct* temp)
{
    return test2(temp);
}

我还有一个 C# 应用程序，它引用了 C++/CLR“Bridge.dll”，然后使用其中包含的方法。我对此有很多问题：

我无法弄清楚如何在 C# 程序中调用 bridge_test2 ，因为它不知道 api_struct 实际上是什么。我知道我需要在某处封送对象，但我是在 C# 程序还是 C++/CLR 桥中执行此操作？
这似乎是一种公开 API 中所有方法的非常冗长的方式，难道没有一种我错过的更简单的方式吗？（这不使用 P/Invoke！）

编辑： 好的，由于下面的回复，我现在已经有了基础知识，但是我的结构（在本例中称之为“api_struct2”）有C++ 本机代码中的本机枚举和联合，如下所示：

typedef struct
{
    enum_type1  eEnumExample;
    union
    {
            long        lData;
            int     iData;
            unsigned char   ucArray[128];
            char        *cString;
            void        *pvoid;
    } uData;
} api_struct2;

我想我已经弄清楚如何让枚举工作；我已在托管代码中重新声明它，并执行“native_enum test = static_cast(eEnumExample)”以将托管版本切换为本机版本。

然而工会让我难住了，我真的不知道如何攻击它..有人有想法吗？

原文

So what I have is a C++ API contained within a *.dll and I want to use a C# application to call methods within the API.

So far I have created a C++ / CLR project that includes the native C++ API and managed to create a "bridge" class that looks a bit like the following:

// ManagedBridge.h
#include <CoreAPI.h>
using namespace __CORE_API;

namespace ManagedAPIWrapper
{
    public ref class Bridge
    {
        public:
            int             bridge_test(void);
            int             bridge_test2(api_struct* temp);
    }
}

// ManagedBridge.cpp
#include <ManagedBridge.h>

int Bridge::bridge_test(void)
{
    return test();
}

int Bridge::bridge_test2(api_struct* temp)
{
    return test2(temp);
}

I also have a C# application that has a reference to the C++/CLR "Bridge.dll" and then uses the methods contained within. I have a number of problems with this:

I can't figure out how to call bridge_test2 within the C# program, as it has no knowledge of what a api_struct actually is. I know that I need to marshal the object somewhere, but do I do it in the C# program or the C++/CLR bridge?
This seems like a very long-winded way of exposing all of the methods in the API, is there not an easier way that I'm missing out? (That doesn't use P/Invoke!)

EDIT: Ok, so I've got the basics working now thanks to responses below, however my struct (call it "api_struct2" for this example) has both a native enum and union in the C++ native code, like the following:

typedef struct
{
    enum_type1  eEnumExample;
    union
    {
            long        lData;
            int     iData;
            unsigned char   ucArray[128];
            char        *cString;
            void        *pvoid;
    } uData;
} api_struct2;

I think I have figured out how to get the enum working; I've re-declared it in managed code and am performing a "native_enum test = static_cast(eEnumExample)" to switch the managed version to native.

However the union has got me stumped, I'm not really sure how to attack it.. Ideas anyone?

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谈下烟灰 2024-09-04 09:45:38

是的，您正在通过引用传递非托管结构。这对于 C# 程序来说是一个问题，指针与垃圾收集非常不兼容。不考虑它可能也没有结构声明的事实。

您可以通过声明结构的托管版本来解决此问题：

public value struct managed_api_struct {
  // Members...
};

可以将方法声明为

int bridge_test2(managed_api_struct temp);   // pass by value

或

int bridge_test2(managed_api_struct% temp);  // pass by reference

现在，如果结构具有超过 4 个字段（约 16 字节），则选择后者。该方法需要将结构体成员一一复制到非托管 api_struct 中并调用非托管类方法。不幸的是，这是必要的，因为托管结构的内存布局是不可预测的。

这一切都非常机械，您可能会从 SWIG 获得帮助。我自己没有使用过它，不确定它是否足够智能来处理传递的结构。

一种完全不同的方法是通过为包装类提供一个构造函数和/或属性来让您构建 api_struct 的内容，从而使包装类更清晰。或者您可以为该结构声明一个包装器引用类，就像在托管代码中一样。

Yes, you are passing an unmanaged structure by reference. That's a problem for a C# program, pointers are quite incompatible with garbage collection. Not counting the fact that it probably doesn't have the declaration for the structure either.

You can solve it by declaring a managed version of the structure:

public value struct managed_api_struct {
  // Members...
};

Now you can declare the method as

int bridge_test2(managed_api_struct temp);   // pass by value

int bridge_test2(managed_api_struct% temp);  // pass by reference

Pick the latter if the structure has more than 4 fields (~16 bytes). The method needs to copy the structure members, one-by-one, into an unmanaged api_struct and call the unmanaged class method. This is unfortunately necessary because the memory layout of a managed structure is not predictable.

This is all pretty mechanical, you might get help from SWIG. Haven't used it myself, not sure if it is smart enough to deal with a passed structure.

A completely different approach is to make the wrapper class cleaner by giving it a constructor and/or properties that lets you build the content of an api_struct. Or you could declare a wrapper ref class for the structure, much like you would in managed code.

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