dotnet-installer/build_projects/dotnet-cli-build/AddMetadataIsPE.cs

// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;
using System;
using System.IO;
using System.Reflection.PortableExecutable;
using System.Collections.Generic;

namespace Microsoft.DotNet.Cli.Build
{
    public class AddMetadataIsPE : Task
    {
        [Required]
        public ITaskItem[] Items { get; set; }

        [Output]
        public ITaskItem[] ResultItems { get; set; }

        public override bool Execute()
        {
            var resultItemsList = new List<ITaskItem>();
            
            foreach (var item in Items)
            {
                var resultItem = new TaskItem(item);
                item.CopyMetadataTo(resultItem);
                
                if (File.Exists(resultItem.GetMetadata("FullPath")) &&
                    HasMetadata(resultItem.GetMetadata("FullPath")))
                {
                    resultItem.SetMetadata("IsPE", "True");
                }
                else
                {
                    resultItem.SetMetadata("IsPE", "False");
                }

                resultItemsList.Add(resultItem);
            }

            ResultItems = resultItemsList.ToArray();

            return true;
        }

        private static bool HasMetadata(string pathToFile)
        {
            try
            {
                using (var inStream = File.OpenRead(pathToFile))
                {
                    using (var peReader = new PEReader(inStream))
                    {
                        return peReader.HasMetadata;
                    }
                }
            }
            catch (BadImageFormatException) { }

            return false;
        }
    }
}