Determine if assembly is installed in the GAC

[Cramer]

I'm wondering if there is an easy way to programmaticall y determine if an
assembly is installed in the GAC.

This would be similar to our ability to easily determine if a file exists
(File.Exists(pa th)) - but for an assembly, of a particular version, etc in
the GAC.

I have googled this and failed to find anything useful.

Thanks

[Willy Denoyette [MVP]]

Re: Determine if assembly is installed in the GAC

"Cramer" <A@B.comwrote in message
news:upVDbjipIH A.3960@TK2MSFTN GP02.phx.gbl...

I'm wondering if there is an easy way to programmaticall y determine if an
assembly is installed in the GAC.
>
This would be similar to our ability to easily determine if a file exists
(File.Exists(pa th)) - but for an assembly, of a particular version, etc in
the GAC.
>
I have googled this and failed to find anything useful.
>
Thanks
>
>

You'll have to cal into the fusion API's (native code API's and COM).
Here is a completes sample that illustrates how one can retrieve the path of
an assembly in the GAC.

// Note that this requires V2 of the framework!!!!.
using System;
using System.Runtime. InteropServices ;
using System.Text;

namespace GacStuff
{
internal class GacApi
{
[DllImport("fusi on.dll")]
internal static extern IntPtr CreateAssemblyC ache(
out IAssemblyCache ppAsmCache,
int reserved);

}
// GAC Interfaces - IAssemblyCache. As a sample, non used vtable entries
declared as dummy.
[ComImport, InterfaceType(C omInterfaceType .InterfaceIsIUn known),
Guid("e707dcde-d1cd-11d2-bab9-00c04f8eceae")]
internal interface IAssemblyCache
{
int Dummy1();
[PreserveSig()]
IntPtr QueryAssemblyIn fo(
int flags,
[MarshalAs(Unman agedType.LPWStr )]
String assemblyName,
ref ASSEMBLY_INFO assemblyInfo);
int Dummy2();
int Dummy3();
int Dummy4();
}
[StructLayout(La youtKind.Sequen tial)]
internal struct ASSEMBLY_INFO
{
public int cbAssemblyInfo;
public int assemblyFlags;
public long assemblySizeInK B;
[MarshalAs(Unman agedType.LPWStr )]
public String currentAssembly Path;
public int cchBuf;
}

class Program
{
static void Main()
{
try
{
Console.WriteLi ne(QueryAssembl yInfo("System") );
}
catch(System.IO .FileNotFoundEx ception e)
{
Console.WriteLi ne(e.Message);
}
}
// If assemblyName is not fully qualified, a random matching may be
returned!!!!
public static String QueryAssemblyIn fo(String assemblyName)
{
ASSEMBLY_INFO assembyInfo = new ASSEMBLY_INFO ();
assembyInfo.cch Buf = 512;
assembyInfo.cur rentAssemblyPat h = new String('\0',
assembyInfo.cch Buf) ;
IAssemblyCache assemblyCache = null;
// Get IAssemblyCache pointer
IntPtr hr = GacApi.CreateAs semblyCache(out assemblyCache, 0);
if (hr == IntPtr.Zero)
{
hr = assemblyCache.Q ueryAssemblyInf o(1, assemblyName, ref
assembyInfo);
if(hr != IntPtr.Zero)
Marshal.ThrowEx ceptionForHR(hr .ToInt32());
}
else
Marshal.ThrowEx ceptionForHR(hr .ToInt32());
return assembyInfo.cur rentAssemblyPat h;
}
}
}

Willy.

[Cramer]

Re: Determine if assembly is installed in the GAC

Thanks for the code! I never would have had the time to come up with this
and instead documented assumptions my code would have instead have made
about the existance of the assembly in the GAC. Now it will be able to test
and report on those assumptions when invalid, before choking. I'll give it a
whirl.

-Cramer


"Willy Denoyette [MVP]" <willy.denoyett e@telenet.bewro te in message
news:OeqsHKjpIH A.3568@TK2MSFTN GP04.phx.gbl...

"Cramer" <A@B.comwrote in message
news:upVDbjipIH A.3960@TK2MSFTN GP02.phx.gbl...

>I'm wondering if there is an easy way to programmaticall y determine if an
>assembly is installed in the GAC.
>>
>This would be similar to our ability to easily determine if a file exists
>(File.Exists(p ath)) - but for an assembly, of a particular version, etc
>in the GAC.
>>
>I have googled this and failed to find anything useful.
>>
>Thanks
>>
>>

>
You'll have to cal into the fusion API's (native code API's and COM).
Here is a completes sample that illustrates how one can retrieve the path
of an assembly in the GAC.
>
// Note that this requires V2 of the framework!!!!.
using System;
using System.Runtime. InteropServices ;
using System.Text;
>
namespace GacStuff
{
internal class GacApi
{
[DllImport("fusi on.dll")]
internal static extern IntPtr CreateAssemblyC ache(
out IAssemblyCache ppAsmCache,
int reserved);
>
}
// GAC Interfaces - IAssemblyCache. As a sample, non used vtable
entries declared as dummy.
[ComImport, InterfaceType(C omInterfaceType .InterfaceIsIUn known),
Guid("e707dcde-d1cd-11d2-bab9-00c04f8eceae")]
internal interface IAssemblyCache
{
int Dummy1();
[PreserveSig()]
IntPtr QueryAssemblyIn fo(
int flags,
[MarshalAs(Unman agedType.LPWStr )]
String assemblyName,
ref ASSEMBLY_INFO assemblyInfo);
int Dummy2();
int Dummy3();
int Dummy4();
}
[StructLayout(La youtKind.Sequen tial)]
internal struct ASSEMBLY_INFO
{
public int cbAssemblyInfo;
public int assemblyFlags;
public long assemblySizeInK B;
[MarshalAs(Unman agedType.LPWStr )]
public String currentAssembly Path;
public int cchBuf;
}
>
class Program
{
static void Main()
{
try
{
Console.WriteLi ne(QueryAssembl yInfo("System") );
}
catch(System.IO .FileNotFoundEx ception e)
{
Console.WriteLi ne(e.Message);
}
}
// If assemblyName is not fully qualified, a random matching may be
returned!!!!
public static String QueryAssemblyIn fo(String assemblyName)
{
ASSEMBLY_INFO assembyInfo = new ASSEMBLY_INFO ();
assembyInfo.cch Buf = 512;
assembyInfo.cur rentAssemblyPat h = new String('\0',
assembyInfo.cch Buf) ;
IAssemblyCache assemblyCache = null;
// Get IAssemblyCache pointer
IntPtr hr = GacApi.CreateAs semblyCache(out assemblyCache, 0);
if (hr == IntPtr.Zero)
{
hr = assemblyCache.Q ueryAssemblyInf o(1, assemblyName, ref
assembyInfo);
if(hr != IntPtr.Zero)
Marshal.ThrowEx ceptionForHR(hr .ToInt32());
}
else
Marshal.ThrowEx ceptionForHR(hr .ToInt32());
return assembyInfo.cur rentAssemblyPat h;
}
}
}
>
Willy.
>
>

[Ignacio Machin ( .NET/ C# MVP )]

Re: Determine if assembly is installed in the GAC

On Apr 24, 12:32 pm, "Cramer" <A...@B.comwrot e:

I'm wondering if there is an easy way to programmaticall y determine if an
assembly is installed in the GAC.
>
This would be similar to our ability to easily determine if a file exists
(File.Exists(pa th)) - but for an assembly, of a particular version, etc in
the GAC.
>
I have googled this and failed to find anything useful.
>
Thanks

Hi,

IT should be simple, first you need a reference to the assembly (you
can use Assembly.GetAss embly(typeof( XXXX ) ); where XXXX is defined
in that assembly)
Then using Assembly.Locati on should be enough.

[Willy Denoyette [MVP]]

Re: Determine if assembly is installed in the GAC

"Ignacio Machin ( .NET/ C# MVP )" <ignacio.machin @gmail.comwrote in
message
news:e63b059c-0512-40de-a491-9a484a37204f@y3 8g2000hsy.googl egroups.com...
On Apr 24, 12:32 pm, "Cramer" <A...@B.comwrot e:

I'm wondering if there is an easy way to programmaticall y determine if an
assembly is installed in the GAC.
>
This would be similar to our ability to easily determine if a file exists
(File.Exists(pa th)) - but for an assembly, of a particular version, etc in
the GAC.
>
I have googled this and failed to find anything useful.
>
Thanks

Hi,

IT should be simple, first you need a reference to the assembly (you
can use Assembly.GetAss embly(typeof( XXXX ) ); where XXXX is defined
in that assembly)
Then using Assembly.Locati on should be enough.


But this won't return the GAC location, nor will it tell you whether the
assembly is actually stored in the GAC.

Willy.

[parez]

Re: Determine if assembly is installed in the GAC

On Apr 24, 12:32 pm, "Cramer" <A...@B.comwrot e:

I'm wondering if there is an easy way to programmaticall y determine if an
assembly is installed in the GAC.
>
This would be similar to our ability to easily determine if a file exists
(File.Exists(pa th)) - but for an assembly, of a particular version, etc in
the GAC.
>
I have googled this and failed to find anything useful.
>
Thanks

Try Assembly.LoadWi thPartialName(" SomeName");

if returned value is null then it is not in gac..
if you get a non null value , then check the GlobalAssemblyC ache.

that mite work..

[Cramer]

Re: Determine if assembly is installed in the GAC

RE:

IT should be simple, first you need a reference to the assembly (you
can use Assembly.GetAss embly(typeof( XXXX ) ); where XXXX is defined
in that assembly)
Then using Assembly.Locati on should be enough.

I should have been more specific. I want to know if an assembly is
installed in the GAC *before* attempting to load it. This would be akin to
using File.Exists() before attempting to open a file.

Your approach assumes that the assembly is already loaded, which it is not
in my case. In my case I want to determine if an assembly of a particular
version etc is in the GAC, then load it if it's there, or write the fact to
a log if it's not in the GAC.

-Cramer

[parez]

Re: Determine if assembly is installed in the GAC

On Apr 24, 5:15 pm, "Cramer" <A...@B.comwrot e:

RE:
>

IT should be simple, first you need a reference to the assembly (you
can use Assembly.GetAss embly(typeof( XXXX ) ); where XXXX is defined
in that assembly)
Then using Assembly.Locati on should be enough.

>
I should have been more specific. I want to know if an assembly is
installed in the GAC *before* attempting to load it. This would be akin to
using File.Exists() before attempting to open a file.
>
Your approach assumes that the assembly is already loaded, which it is not
in my case. In my case I want to determine if an assembly of a particular
version etc is in the GAC, then load it if it's there, or write the fact to
a log if it's not in the GAC.
>
-Cramer

Try Assembly.LoadWi thPartialName(" SomeName");

if returned value is null then it is not in gac..
if you get a non null value , then check the GlobalAssemblyC ache.

that mite work..