C# DLL에서 Win32 C/C++처럼 dllexport 함수를 제공하는 방법 - 두 번째 이야기

예전에 다뤘던 방법은,

C# DLL에서 Win32 C/C++처럼 dllexport 함수를 제공하는 방법
; https://www.sysnet.pe.kr/2/0/11052

UnmanagedExports라는 NuGet 패키지를 통해 가능했는데, 이번에 설명할 방법은 Microsoft.DotNet.ILCompiler에서 제공합니다.

Building Native Libraries with CoreRT
; https://github.com/dotnet/corert/tree/master/samples/NativeLibrary

Writing Native Libraries in C# and using them in other languages
; https://dev.to/encrypt0r/writing-native-libraries-in-c-3kl

현재 ILCompiler는 정규 nuget.org가 아닌 myget.org에서 배포하므로,

Microsoft.DotNet.ILCompiler v1.0.0-alpha-27527-01
; https://dotnet.myget.org/feed/dotnet-core/package/nuget/Microsoft.DotNet.ILCompiler

다음의 글에 설명했던 데로,

Visual Studio 없이 최신 C# (8.0) 컴파일러를 사용하는 방법
; https://www.sysnet.pe.kr/2/0/11834

feed 소스를 "https://dotnet.myget.org/F/dotnet-core/api/v3/index.json"로 설정한 항목을 추가해야 합니다.

---

그럼 예제를 다뤄볼까요? ^^

우선 .NET Core 라이브러리 프로젝트를 만들고 소스 코드를 다음과 같이 입력합니다.

using System;
using System.Runtime.InteropServices;

public class Class1
{
    [NativeCallable(EntryPoint = "add", CallingConvention = CallingConvention.StdCall)]
    public static int Add(int a, int b)
    {
        return a + b;
    }
}

namespace System.Runtime.InteropServices
{
    [AttributeUsage(AttributeTargets.Method)]
    public sealed class NativeCallableAttribute : Attribute
    {
        public string EntryPoint;
        public CallingConvention CallingConvention;
        public NativeCallableAttribute() { }
    }
}

NativeCallable 특성은 ILCompiler가 인식만 하면 되기 때문에 위와 같이 임의로 정의해서 포함하면 됩니다. 그다음, 현재의 라이브러리 프로젝트에 이전에 추가했던 "Pakcage source"로부터 Microsoft.DotNet.ILCompiler 패키지를 추가합니다.

Install-Package Microsoft.DotNet.ILCompiler -Version 1.0.0-alpha-27527-01

그럼, csproj에 다음의 설정이 추가됩니다.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <Platforms>x64</Platforms>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.DotNet.ILCompiler" Version="1.0.0-alpha-27527-01" />
  </ItemGroup>

</Project>

.NET 5 / .NET Core - UnmanagedCallersOnly 특성을 사용한 함수 내보내기
; https://www.sysnet.pe.kr/2/0/12413

dotnet.exe publish /p:NativeLib=Shared -r win-x64 -c Release

...[project_path]...\bin\x64\Release\netcoreapp2.1\win-x64\native

C:\temp> dotnet publish /p:NativeLib=Shared -r win-x64 -c Release
Microsoft (R) Build Engine version 16.0.385-preview+g966cdf2ac6 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 22.07 ms for C:\temp\ClassLibrary1\ClassLibrary1.csproj.
C:\Program Files\dotnet\sdk\3.0.100-preview-010184\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.RuntimeIdentifierInference.targets(151,5): message NETSDK1057: You are using a preview version of .NET Core. See: https://aka.ms/dotnet-core-preview [C:\temp\ClassLibrary1\ClassLibrary1.csproj]
  ClassLibrary1 -> C:\temp\ClassLibrary1\bin\Release\netcoreapp2.1\win-x64\ClassLibrary1.dll
  Generating compatible native code. To optimize for size or speed, visit https://aka.ms/OptimizeCoreRT
libcpmt.lib(nothrow.obj) : fatal error LNK1112: module machine type 'x86' conflicts with target machine type 'x64' [C:\temp\ClassLibrary1\ClassLibrary1.csproj]
%USERPROFILE%\.nuget\packages\microsoft.dotnet.ilcompiler\1.0.0-alpha-27527-01\build\Microsoft.NETCore.Native.targets(333,5): error MSB3073: The command "link  @"obj\Release\netcoreapp2.1\win-x64\native\link.rsp"" exited with code 1112. [C:\temp\ClassLibrary1\ClassLibrary1.csproj]

C:\temp\ClassLibrary1\ClassLibrary2> "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
**********************************************************************
** Visual Studio 2019 Developer Command Prompt v16.8.0
** Copyright (c) 2020 Microsoft Corporation
**********************************************************************
[vcvarsall.bat] Environment initialized for: 'x64'

C:\temp\ClassLibrary1\ClassLibrary2> dotnet publish /p:NativeLib=Shared -r win-x64 -c Release
Microsoft (R) Build Engine version 16.8.0+126527ff1 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
  ClassLibrary2 -> C:\temp\ClassLibrary1\ClassLibrary2\bin\x64\Release\netcoreapp3.1\win-x64\ClassLibrary2.dll
  Generating compatible native code. To optimize for size or speed, visit https://aka.ms/OptimizeCoreRT
     Creating library bin\x64\Release\netcoreapp3.1\win-x64\native\ClassLibrary2.lib and object bin\x64\Release\netcoreapp3.1\win-x64\native\ClassLibrary2.exp
  ClassLibrary2 -> C:\temp\ClassLibrary1\ClassLibrary2\bin\x64\Release\netcoreapp3.1\win-x64\publish\

C:\temp\demo_code\nativeLib> dotnet publish /p:NativeLib=Shared -r win-x64 -c release -o win-x64-shared
Microsoft (R) Build Engine version 16.8.0+126527ff1 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored C:\temp\demo_code\nativeLib\nativeLib.csproj (in 1.58 min).
  nativeLib -> C:\temp\demo_code\nativeLib\bin\release\net5.0\win-x64\nativeLib.dll
C:\Users\testusr\.nuget\packages\microsoft.dotnet.ilcompiler\1.0.0-alpha-29408-02\build\Microsoft.NETCore.Native.Windows.props(109,5): error : Platform linker not found. To fix this problem, download and install Visual Studio 2017 from http://visualstudio.com. Make sure to install the Desktop Development for C++ workload. [C:\temp\demo_code\nativeLib\nativeLib.csproj]