Check if assembly is a ref assembly

IsRef.cs

using System;
using System.IO;
using System.Reflection.Metadata;
using System.Reflection.PortableExecutable;

try
{
    using var file = new FileStream(args[0], FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
    using var pe = new PEReader(file);
    var metadataReader = pe.GetMetadataReader();
    bool found = false;
    foreach (var attributeHandle in metadataReader.GetAssemblyDefinition().GetCustomAttributes())
    {
        var ctorHandle = metadataReader.GetCustomAttribute(attributeHandle).Constructor;
        StringHandle typeNameHandle;
        StringHandle namespaceNameHandle;
        switch (ctorHandle.Kind)
        {
            case HandleKind.MethodDefinition:
                {
                    var ctor = metadataReader.GetMethodDefinition((MethodDefinitionHandle)ctorHandle);
                    var typeDef = metadataReader.GetTypeDefinition(ctor.GetDeclaringType());
                    typeNameHandle = typeDef.Name;
                    namespaceNameHandle = typeDef.Namespace;
                    break;
                }

            case HandleKind.MemberReference:
                {
                    var ctor = metadataReader.GetMemberReference((MemberReferenceHandle)ctorHandle);
                    var typeRef = metadataReader.GetTypeReference((TypeReferenceHandle)ctor.Parent);
                    typeNameHandle = typeRef.Name;
                    namespaceNameHandle = typeRef.Namespace;
                    break;
                }

            default:
                continue;
        }

        if (string.Equals(metadataReader.GetString(typeNameHandle), "ReferenceAssemblyAttribute", StringComparison.Ordinal) &&
            string.Equals(metadataReader.GetString(namespaceNameHandle), "System.Runtime.CompilerServices", StringComparison.Ordinal))
        {
            found = true;
            break;
        }
    }

    Console.WriteLine(found ? "ref assembly" : "not ref assembly");
}
catch (IOException e)
{
    Console.WriteLine("Error reading file: " + e.Message);
}
catch
{
    Console.WriteLine("Invalid managed metadata");
}