Is this DLL managed or unmanaged?

Question

I hold before you a DLL. Using only the Win32 SDK, can you tell me if this DLL is a .NET assembly?

Why? Our application loads plugins in the form of DLLs. We are try

Answer 1

To determine whether a DLL (or EXE) is managed or unmanaged, use dumpbin.exe with the /dependents switch. If you see mscoree.dll in the output, then the assembly is a managed assembly.

For example, for a managed DLL that I created in Visual Studio 2010, I get the following output:

Dump of file <MANAGED_DLL>.dll

File Type: DLL

  Image has the following dependencies:

    mscoree.dll

  Summary

        2000 .reloc
        2000 .rsrc
        2000 .sdata
       12000 .text

dumpbin.exe is delivered as part of the Visual Studio Tools. To run it, a convenient way to do so is via the Visual Studio Command Prompt. For example, from my Windows 7 machine running Visual Studio 2010, I find the Visual Studio Command Prompt in the Windows Start Menu at:

Microsoft Visual Studio 2010 => Visual Studio Tools => Visual Studio Command Prompt (2010)

Then, within the Visual Studio Command Prompt just enter:

dumpbin /dependents DLL_OF_INTEREST.DLL

or

dumpbin /dependents EXE_OF_INTEREST.EXE

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As an alternative, you can use the corflags.exe utility that is also included with Visual Studio Tools. Running it from the Visual Studio Command Prompt on an unmanaged assembly:

corflags UNMANAGED.DLL

..you'll get:

corflags : error CF008 : The specified file does not have a valid managed header

...whereas on a managed assembly, you'll get something like:

Version   : v2.0.50727
CLR Header: 2.5
PE        : PE32
CorFlags  : 1
ILONLY    : 1
32BIT     : 0
Signed    : 0

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Related:

• How to determine if a .NET assembly was built for x86 or x64?, and
• How can I detect the type of a dll? (COM, .NET, WIN32).

Answer 2

You can check the PE header information for the information about what type of information is contained in the DLL. This article describes how to accomplish this in detail.

Answer 3

I would simply try to load it as a .NET assembly, and if it fails, fall back to "unmanaged" interface.