csproj copy files depending on operating system

Question

I am using .NET Core to build a cross platform class library. Depending on the operating system that the C# .NET Core project is built for using a .csproj file, I need to co

Answer 1

For differentiating between Windows & Mac/Linux you can use the $(os) property: this gives you Windows_NT for Windows and UNIX for Mac/Linux.

For differentiating between Mac & Linux, at least on recent versions of MSBuild, you can use RuntimeInformation.IsOSPlatform.

So, combined, your csproj can have something like this:

<ItemGroup>
    <Content Include="libNative.dll" Condition=" '$(OS)' == 'Windows_NT' ">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </Content>
    <Content Include="libNative.so" Condition=" '$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::Linux)))' ">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </Content>
    <Content Include="libNative.dylib" Condition=" '$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::OSX)))' ">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </Content>
</ItemGroup>

To the best of my knowledge, this should work in all recent versions of .Net Core, Mono and .Net Framework.

In older versions, you'd need to resort to evil trickery for differentiating between Mac & Linux:

For Linux -> Condition=" '$(OS)' == 'Unix' and ! $([System.IO.File]::Exists('/usr/lib/libc.dylib')) "

For Mac -> Condition=" '$(OS)' == 'Unix' and $([System.IO.File]::Exists('/usr/lib/libc.dylib')) "

Sources:

• https://github.com/Microsoft/msbuild/issues/539
• https://github.com/Microsoft/msbuild/issues/2468

Answer 2

I did have a problem like this and ended up saving the dll in a resource and lodaing the dll for X86 or X64, when the library first initilized. It was the cleanst way for me.

Alternative when you include the dll in nuget you have also to make sure the same dll get recoped when the som one remove/clean the bin mapp.

So you have to add the file to nuger and also create a targets on build file to recopy the dll on build

Here is what i did.

internal class EmbeddedDllClass
{
    public static void LoadAllDll()
    {
        Assembly assem = Assembly.GetExecutingAssembly();
        if (IntPtr.Size == 8)
        {
            var path = Path.Combine(string.Join("\\", assem.Location.Split('\\').Reverse().Skip(1).Reverse()), "x64");

            if (!Directory.Exists(path))
                Directory.CreateDirectory(path);

            path = Path.Combine(path, "SQLite.Interop.dll");

            if (!File.Exists(path))
                File.WriteAllBytes(path, Properties.Resources.SQLite_Interop_64);
        }
        else if (IntPtr.Size == 4)
        {
            var path = Path.Combine(string.Join("\\", assem.Location.Split('\\').Reverse().Skip(1).Reverse()), "x86");

            if (!Directory.Exists(path))
                Directory.CreateDirectory(path);

            path = Path.Combine(path, "SQLite.Interop.dll");

            if (!File.Exists(path))
                File.WriteAllBytes(path, Properties.Resources.SQLite_Interop_86);

        }
    }
}

And then just call it

EmbeddedDllClass.LoadAllDll();