Exposing the Global Assembly Cache

If you're familiar with the Global Assembly Cache (GAC) you're probably aware there's a special file system viewer thingy (technical term) sitting over top of the GAC contents at c:\windows\assembly; this is a nice convenience when it comes to registering assemblies in the GAC—simply drag and drop, avoiding a trip to the command line and gacutil –i

More often than not, this is all good. When you need to dive into the real GAC, to extract an assembly, drop in debugging symbols, or whatever, you'll quickly realise the viewer is somewhat limiting.

To get past the GAC's outer facade, you've got a few options:

• From a command line, browse to c:\windows\assembly\gac_msil
• Map a network drive to \\machine-name\c$\windows\assembly\gac_msil
• Create a virtual drive: subst z: c:\windows\assembly\gac_msil where 'z:' is any unmapped drive letter
• Start –> Run c:\windows\assembly\gac_msil
• Turn off the viewer altogether to browse the GAC directory structure normally within Windows Explorer: create a new DWORD named DisableCacheViewer with a value of 1 below the HKLM\Software\Microsoft\Fusion key

Five ways to do the same thing? Well this is Windows after all—and there are probably more!!! ;)

If you drop the gac_msil bit you'll find there are other directories that make up the GAC proper to explorer but most of what you'll be after resides below gac_msil. Each assembly is represented in by name as a folder with different versions represented as sub folders named as the version number with a GUID appended; the assembly proper will live in one of these folders.

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