Cannot load native DLL from C#

Question

0.00/5 (No votes)

See more:

Hi Everyone,

I have a DLL (native Windows, 32 bit, no COM) which I used to call from a managed C++ wrapper using LoadLibrary and GetProcAddress statements. All went fine, the DLL got loaded, I was able to retrieve the entrypoints and call all the required methods using explicit marshalling. This is on a 32 bit environment, no 64 bits are envolved.

For reasons beyond my control I am forced to rewrite this mechanism using C#, so I created the same (wrapper) classes in C# and created DllImport-attributed signatures for all my DLL functions. However, when I call the first method, I am getting an BadImageFormatException, no matter what function I call. I even declared a non-existing function, but the result was the same exception.

Googling on this topic provides me a lot of 32 vs 64 bit issues, but since my environment is completely 32 bit this solves nothing for me. The only thing that worries me, is when I inspect the DLL using the dependency walker (depends.exe) it shows the following message: "Warning: At least one module has an unresolved import due to a missing export function in a delay-load dependent module.". The IEFRAME.DLL is marked red, but using the LoadLibrary statements I was able to load the DLL.

The declaring statement is:
[DllImport(@"retrievalNLE.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern void SetWebsearchNLETraceLevel(Int32 level);

(but I have also tested with the options CharSet and SetLastError omitted, as well as with every calling convention )

The result is:
System.BadImageFormatException: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)

The native Windows LastError is 2.

The file and all dependencies are located in the c:\windows\system32 directory.

Any suggestions on how to call such a DLL from C# are greatly appreciated.

Kind regards,
Martin de Jong
The Netherlands

Posted 11-Mar-10 2:15am

MartinDeJong

Updated 11-Mar-10 5:34am

v3

Add a Solution

4 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Richard MacCutchan · Answer 1 · 2010-03-11T05:30:00

Solution 2

Error code 2 is "cannot find file", so it looks like your DLL is not anywhere that the loader can find it. Try making sure it's in WINDOWS\Sytem32 or provide the full path in your DllImport statement.

Posted 11-Mar-10 5:30am

Richard MacCutchan

Ilya Builuk · Answer 2 · 2010-03-11T02:20:00

I use to call native function from Windows library this approach:

C#

using System.Runtime.InteropServices;
....
[DllImport("Netapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
       private static extern int NetServerGetInfo(
           string serverName,
           int level,
           out IntPtr pSERVER_INFO_XXX);

....

Also see pinvoke.net

MartinDeJong · Answer 3 · 2010-03-11T05:37:00

Solution 3

Thanks for the answers so far regarding the DllImport-use as well as the c:\windows issue. Unfortunately they are not appropriate, so I have updated the question to indicate this.

Posted 11-Mar-10 5:37am

MartinDeJong

Richard MacCutchan · Answer 4 · 2010-03-11T05:48:00

Solution 4

MartinDeJong wrote:
The file and all dependencies are located in the c:\windows\system32 directory.

Well the only other answer must be that the dll is somehow corrupt; I can't see any other reason why you would get this error.

Posted 11-Mar-10 5:48am