A simple wrapper for GAC.cs from Microsoft KB Article KB317540

SimpleGAC.cs

// System.GAC (a .Net wrapper for Fusion) implementation was too messy. Simplified here.
//
// Note, installing an assembly with the REFRESH flag specified does NOT work as advertised.
// Overwriting old GAC'd assemblies must be done manually as implemented below.
//

using System.Reflection;
using System.Text;

namespace Xcud.System.GAC
{
    public static class Simplified
    {
        public static void Install(string assemblyName, string path)
        {
            System.EnterpriseServices.Internal.Publish publisher = new System.EnterpriseServices.Internal.Publish();

            AssemblyName asm = AssemblyName.GetAssemblyName(path);

            bool installToGAC = true;

            IAssemblyEnum enumerator = System.GAC.AssemblyCache.CreateGACEnum();
            while (true)
            {
                IAssemblyName name = null;
                enumerator.GetNextAssembly(IntPtr.Zero, out name, 0);
                if (name == null)
                    break;

                uint len = 1024;
                StringBuilder sb = new StringBuilder((int)len);
                name.GetName(ref len, sb);
                if (sb.Length == 0)
                    break;

                if (!string.IsNullOrEmpty(name) && sb.ToString().ToLower().StartsWith(assemblyName.ToLower()))
                {
                    len = 1024;
                    StringBuilder displayName = new StringBuilder((int)len);
                    name.GetDisplayName(displayName, ref len, 0);

                    // uninstall it
                    string location = Assembly.ReflectionOnlyLoad(displayName.ToString()).Location;
                    publisher.GacRemove(location);
                }

                if (sb.ToString().ToLower().StartsWith(asm.Name.ToLower()))
                {
                    len = 1024;
                    StringBuilder displayName = new StringBuilder((int)len);
                    name.GetDisplayName(displayName, ref len, 0);

                    string asmPath = Assembly.ReflectionOnlyLoad(displayName.ToString()).Location;
                    int result = -1;
                    try
                    {
                        Version foundVersion = AssemblyName.GetAssemblyName(asmPath).Version;
                        result = foundVersion.CompareTo(asm.Version);
                    }
                    catch(Exception) { }
                    if (result < 0) // found version is older
                    {
                        // uninstall it
                        string location = Assembly.ReflectionOnlyLoad(displayName.ToString()).Location;
                        publisher.GacRemove(location);
                    }
                    else if (result == 0) // found version is the same
                    {
                        string location = Assembly.ReflectionOnlyLoad(displayName.ToString()).Location;
                        publisher.GacRemove(location);
                    }
                    else if (result > 0) // found version is newer
                    {
                        installToGAC = false;
                    }
                }
            }

            if (installToGAC)
                publisher.GacInstall(path);
        }

        public static void Remove(string assemblyName)
        {
            System.EnterpriseServices.Internal.Publish publisher = new System.EnterpriseServices.Internal.Publish();

            IAssemblyEnum enumerator = System.GAC.AssemblyCache.CreateGACEnum();
            while (true)
            {
                IAssemblyName name = null;
                enumerator.GetNextAssembly(IntPtr.Zero, out name, 0);
                if (name == null)
                    break;

                uint len = 1024;
                StringBuilder sb = new StringBuilder((int)len);
                name.GetName(ref len, sb);
                if (sb.Length == 0)
                    break;

                if sb.ToString().ToLower().StartsWith(assemblyName.ToLower()))
                {
                    len = 1024;
                    StringBuilder displayName = new StringBuilder((int)len);
                    name.GetDisplayName(displayName, ref len, 0);

                    // uninstall it
                    string location = Assembly.ReflectionOnlyLoad(displayName.ToString()).Location;
                    publisher.GacRemove(location);
                }
            }
        }
    }
}