Test to see if interop is working on dotnet core

interopcheck.cs

using System;
using System.Security;
using System.Runtime.InteropServices;

namespace consoletest
{
    
    class Program
    {
        [DllImport("libc")]
        static extern int uname(IntPtr buf);

        [SuppressUnmanagedCodeSecurity]
        [DllImport("/usr/lib/libdl.so")]
        static extern IntPtr dlopen(string filename, int flags);

        [DllImport("/usr/lib/libdl.so")]
        static extern IntPtr dlerror();

        [DllImport("/usr/lib/libdl.so")]
        static extern IntPtr dlsym(IntPtr handle, String symbol);

        static string GetUname()
        {
            var buffer = Marshal.AllocHGlobal(8192);
            try
            {
                if (uname(buffer) == 0)
                {
                    return Marshal.PtrToStringAnsi(buffer);
                }
                return string.Empty;
            }
            catch
            {
                return string.Empty;
            }
            finally
            {
                if (buffer != IntPtr.Zero)
                {
                    Marshal.FreeHGlobal(buffer);
                }
            }
        }
        
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World! from: " + GetUname());

            var ret = dlopen("/usr/local/lib/libpng.so", 2);
            if (ret == IntPtr.Zero)
            {
                var errorMsg = Marshal.PtrToStringAnsi(dlerror());
                Console.WriteLine(errorMsg);
            }
                    
        }
    }
}

FreeBSD 11.3

Runtime Environment:
OS Name: FreeBSD
OS Version: 11
OS Platform: FreeBSD
RID: freebsd.11-x64
Base Path: /usr/local/share/dotnet/sdk/3.0.100-preview-010021/