Programmatically To check dll exists in Gac or not.If so display it in grid

Question

I will have a list of dll's in a folder, I want to check a dll for a application exists or not. If so i want to add that application name in grid.Can any one tell how to do it programmatically. Thanks in Advance

Answer 1

Do an assembly.LoadFrom and check GlobalAssemblyCache

testAssembly = Assembly.LoadFrom(dllname);

if (!testAssembly.GlobalAssemblyCache)
{
  // not in gac
}

Answer 2

I think the proper way is Fusion COM API.

Here how to use it :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace IsAssemblyInGAC
{
    internal class GacApi
    {
        [DllImport("fusion.dll")]
        internal static extern IntPtr CreateAssemblyCache(
            out IAssemblyCache ppAsmCache, int reserved);
    }

    // GAC Interfaces - IAssemblyCache. As a sample, non used vtable entries     
    [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
    Guid("e707dcde-d1cd-11d2-bab9-00c04f8eceae")]
    internal interface IAssemblyCache
    {
        int Dummy1();
        [PreserveSig()]
        IntPtr QueryAssemblyInfo(
            int flags,
            [MarshalAs(UnmanagedType.LPWStr)]
            String assemblyName,
            ref ASSEMBLY_INFO assemblyInfo);

        int Dummy2();
        int Dummy3();
        int Dummy4();
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct ASSEMBLY_INFO
    {
        public int cbAssemblyInfo;
        public int assemblyFlags;
        public long assemblySizeInKB;

        [MarshalAs(UnmanagedType.LPWStr)]
        public String currentAssemblyPath;

        public int cchBuf;
    }

    class Program
    {
        static void Main()
        {
            try
            {
                Console.WriteLine(QueryAssemblyInfo("System"));
            }
            catch(System.IO.FileNotFoundException e)
            {
                Console.WriteLine(e.Message);
            }
        }

        // If assemblyName is not fully qualified, a random matching may be 
        public static String QueryAssemblyInfo(String assemblyName)
        {
            ASSEMBLY_INFO assembyInfo = new ASSEMBLY_INFO ();
            assembyInfo.cchBuf = 512;
            assembyInfo.currentAssemblyPath = new String('\0', 
                assembyInfo.cchBuf) ;

            IAssemblyCache assemblyCache = null;

            // Get IAssemblyCache pointer
            IntPtr hr = GacApi.CreateAssemblyCache(out assemblyCache, 0);
            if (hr == IntPtr.Zero)
            {
                hr = assemblyCache.QueryAssemblyInfo(1, assemblyName, ref assembyInfo);
                if (hr != IntPtr.Zero)
                {
                    Marshal.ThrowExceptionForHR(hr.ToInt32());
                }
            }
            else
            {
                Marshal.ThrowExceptionForHR(hr.ToInt32());
            }
            return assembyInfo.currentAssemblyPath;
        }
    }
}

Use QueryAssemblyInfo method.