Check GAC for an assembly

Question

How to programmatically check GAC for an assembly?

Answer 1

Without even trying to get complicated, you could just shell out to gacutil and capture the output. For example, gacutil /l Microsoft.Practices.Unity gives me:

Microsoft (R) .NET Global Assembly Cache Utility.  Version 3.5.30729.1
Copyright (c) Microsoft Corporation.  All rights reserved.

The Global Assembly Cache contains the following assemblies:
  Microsoft.Practices.Unity, Version=1.2.0.0, Culture=neutral, PublicKeyToken=31
bf3856ad364e35, processorArchitecture=MSIL

Number of items = 1

versus gacutil /l Some.Nonexistant.Assembly:

Microsoft (R) .NET Global Assembly Cache Utility.  Version 3.5.30729.1
Copyright (c) Microsoft Corporation.  All rights reserved.

The Global Assembly Cache contains the following assemblies:

Number of items = 0

This is easy to implement and parse and isn't dependent on any third-party implementations.

Answer 2

It's better to use ReflectionOnlyLoad Method. this method loads an assembly into the reflection-only context, where it can be examined but not executed.

Answer 3

From .NET, the reflection API - Assembly.Load(...) will throw a FileNotFoundException if it does not find the assembly. The API requires a fully qualified assembly name, so I assume it must be in the GAC. I am using it to test for the presence of SQL Server Compact Edition:

Assembly foo = Assembly.Load("System.Data.SqlServerCe, Version=3.5.1.0, " +
    "Culture=neutral, PublicKeyToken=89845dcd8080cc91");

Answer 4

You can use the Fusion COM API. Junfeng Zhang wrote a managed wrapper. It's from 2004, though, so I don't know how well it works anymore.

Answer 5

Do you want to probe the GAC for an assembly or do you just want to know that the assembly exists on the machine?

If you dont care that the assembly is actually in the GAC, but just loadable on the machine (from the appdomain) you can just use LoadAssembly with the assemblies name (strong, common, full, etc). If the assembly can be loaded by Fusion it will be and then you will know it exists.