C# macOS getrlimit example via DllImport

getrlimit.csproj

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
  </PropertyGroup>

</Project>

Program.cs

using System.Runtime.InteropServices;

namespace getrlimit;

class Program
{
    [DllImport("libc", CallingConvention = CallingConvention.Cdecl)]
    public static extern int getrlimit(int resource, IntPtr rlp);

    [StructLayout(LayoutKind.Sequential)]
    public struct rlimit
    {
        public Int64 rlim_cur;
        public Int64 rlim_max;
    }

    static void Main(string[] args)
    {
        int RLIMIT_STACK = 3;

        rlimit joy = new();

        unsafe
        {
            void *rlimitPtr = &joy;

            getrlimit(RLIMIT_STACK, new(rlimitPtr));
        }

        Console.WriteLine(joy.rlim_cur);
        Console.WriteLine(joy.rlim_max);
    }
}