Register a dll into the GAC - but then it doesn't show up in the assembly window

Question

I have this code to register dlls into my gac

 Assembly asm = Assembly.LoadFrom(argument);
    RegistrationServices regAsm = new RegistrationServices();
    bool bResult = regAsm.RegisterAssembly(asm, AssemblyRegistrationFlags.SetCodeBase);

and that works fine, i'm getting true to bResult, but when i open the GAC window i expected to see the dll there, but it is not. Can anyone explain me why?

When i drop the dll into the GAC window i see it there.

Hans Passant Hans Passant · Accepted Answer · 2010-04-09T22:43:46

It is rather strange that this isn't wrapped by the .NET framework. The necessary fusion declarations are readily available. This code worked well:

using System;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;

static class GacUtil {

    public static void InstallAssembly(string path, bool forceRefresh) {
        IAssemblyCache iac = null;
        CreateAssemblyCache(out iac, 0);
        try {
            uint flags = forceRefresh ? 2u : 1u;
            int hr = iac.InstallAssembly(flags, path, IntPtr.Zero);
            if (hr < 0) Marshal.ThrowExceptionForHR(hr);
        }
        finally {
            Marshal.FinalReleaseComObject(iac);
        }
    }

    public static void UninstallAssembly(string displayName) {
        IAssemblyCache iac = null;
        CreateAssemblyCache(out iac, 0);
        try {
            uint whatHappened;
            int hr = iac.UninstallAssembly(0, displayName, IntPtr.Zero, out whatHappened);
            if (hr < 0) Marshal.ThrowExceptionForHR(hr);
            switch (whatHappened) {
                case 2: throw new InvalidOperationException("Assembly still in use");
                case 5: throw new InvalidOperationException("Assembly still has install references");
                case 6: throw new System.IO.FileNotFoundException();    // Not actually raised
            }
        }
        finally {
            Marshal.FinalReleaseComObject(iac);
        }
    }


    [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("e707dcde-d1cd-11d2-bab9-00c04f8eceae")]
    internal interface IAssemblyCache {
        [PreserveSig]
        int UninstallAssembly(uint flags, [MarshalAs(UnmanagedType.LPWStr)] string assemblyName, IntPtr pvReserved, out uint pulDisposition);
        [PreserveSig]
        int QueryAssemblyInfo(uint dwFlags, [MarshalAs(UnmanagedType.LPWStr)] string pszAssemblyName, IntPtr pAsmInfo);
        [PreserveSig]
        int CreateAssemblyCacheItem(/* arguments omitted */);
        [PreserveSig]
        int CreateAssemblyScavenger(out object ppAsmScavenger);
        [PreserveSig]
        int InstallAssembly(uint dwFlags, [MarshalAs(UnmanagedType.LPWStr)] string pszManifestFilePath, IntPtr pvReserved);
    }

    [DllImport("mscorwks.dll", PreserveSig = false)]  // NOTE: use "clr.dll" in .NET 4+
    internal static extern void CreateAssemblyCache(out IAssemblyCache ppAsmCache, int reserved);
}

Don't forget to press F5 in the Explorer window to refresh the view if you are adding and removing assemblies with this code.

Register a dll into the GAC - but then it doesn't show up in the assembly window

3 Answers