Background
I have an embedded system which runs an application originally written in C++ and compiled in Visual Studio, which results in a single executable and more than 30 DLLs. These libraries cannot be browsed in VS Object Browser or other tools such as P/Invoke Interop Assistant.
Loading some of the DLLs in Dependency Walker shows that all of them are missing some dependencies deep in their dependency tree (cdfview.dll, dwmapi.dll, w32topl.dll, ...) but according to this question, that is likely not an issue.
I have some of the source code files, and all of the compiled DLLs. The application currently runs without issue, indicating there are no real dependency issues.
I am trying to call some library functions and eventually make a wrapper using C#, but am unable to successfully import and call even the simplest of functions. I always receive the following error:
Unable to load DLL 'dllName.dll': A dynamic link library (DLL)
initialization routine failed. (Exception from HRESULT: 0x8007045A)
Sample Code [EDITED]
From the C++ source code header file I have the following declarations:
#define OB_API __declspec(dllexport) __cdecl
typedef unsigned long DWORD; // From windef.h
typedef DWORD OBSTATUS;
OBSTATUS OB_API TestObj(void);
In the C++ source code file the following definition is given (which would seem to always return true):
BOOL WINAPI DllMain(HANDLE /* hModule */,
DWORD ul_reason_for_call,
LPVOID /* lpReserved */
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_PROCESS_DETACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
break;
}
return TRUE;
}
In my C# application class, I add the following declaration:
[DllImport(#"dllName.dll", CallingConvention=CallingConvention.Cdecl)
public static extern ulong TestObj();
The DLL and C# application binary reside in the same directory.
Questions
From researching the error, it seems there is a large number of reasons this particular exception could be thrown and I was wondering how I could further troubleshoot this type of issue.
Is there any way to get more detailed information on why the initialization routine failed?
(Note: target system is running .NET framework 2.0)
The DLL you are loading contains a DllMain() function. That's pretty common, such a function initializes the state of the DLL. Windows makes sure that this function is called whenever the DLL gets loaded, it will happen automatically the first time you pinvoke a function exported by that DLL.
Problem is, that function returned FALSE to indicate that it could not properly initialize the DLL. That of course does not give a wholeheckofalot of information about why it returned FALSE. Windows can't do anything but generate error 1114, ERROR_DLL_INIT_FAILED. If the DLL itself doesn't output any diagnostic then you can't do anything but debug the code. Start with Project + Properties, Debug tab, tick the "Enable unmanaged code debugging" option.
Fingers crossed that you see a message in the Output window. Odds are not very good. If you don't have the source code for the DLL then you'll need the help of the vendor or author of the DLL. Give him a copy of a test project that fails like this.
Maybe the reason is need to install old Net Framework version like 2.0, 3.0, 3.5,....it's worked for me :D
Related
I am developing an application that communicates with some hardware using the C++ DLL provided by the hardware provider. I also have a header file for this DLL, but no source file. In my C# application, I'm trying to import and call the DLL's functions like this:
public class MyClass
{
[DllImport("CaGe.dll")]
public static extern long someLibraryFunction();
public void callLibFunction()
{
Console.WriteLine("function call: " + someLibraryFunction());
}
}
The library.dll file is located in the same folder as the MyClass.cs file and also the rest of the project files. When I start the debugging session however, I first receive a dialog window from system saying: CAGE InitDll: Erro on load library "CdbClientInit" and after I click OK on that, an unhalted exception on the line where I call the library function occours.
The exception says: System.DllNotFoundException: Exception from HRESULT: 0x8007045A
I found on the internet that this may be caused by a missing DLL that the CaGe.dll needs, so I tried to put the DLL through the Dependency Walker, but the results are a little bit confusing for me. Under the CAGE.DLL there are WS32_32.DLL, VERSION.DLL, KERNEL.DLL and USER32.DLL tabs, I susspect that the libraries I need are somwhere under the USER32.DLL tab, but I don't recognize any of them (if a missing DLL is what is causing this problem).
Any advice would be much appretiated :)
More help to use C++ function in C# please check below URL
http://www.codeproject.com/Questions/107152/Using-a-C-dll-in-a-C-application
We're creating a dll, written in C++, providing access to some hardware. We also have a C# program that uses this dll.
We're having an issue with the versions. Indeed, when running the C# program, it absolutely wants to use the exact C++ dll version it used when compiling. I.e. if the C# program was compiled using C++ dll 1.2.3.4, then the program will refuse to run with C++ dll 1.2.3.5.
I'd like to instruct the C# program to use any C++ dll with version 1.2.anything.
Where can I configure this in the C# project?
This question has been superseded by that one, more related to COM.
Nothing this fancy exists in C++. Using a side-by-side manifest technically permits this but you would have known about it since you would have typed the version number in the manifest of your C# program.
The far more likely explanation is that you actually created a C++/CLI assembly. Many programmers confuse C++/CLI with C++. Easy mistake since that language permits using native C++ code. But it actually gets compiled to a mixed-mode assembly, an assembly that contains both IL and native code. The normal CLR version checking occurs for such an assembly when the CLR loads it, it is only happy with an exact version match. A strong DLL Hell counter-measure.
And the normal CLR version wrangling option is available to bypass this check, a <bindingRedirect> element in your app.exe.config file. As well as controlling the assembly version number the way you do it for your C# code so this isn't necessary.
The easiest way to check if this guess is accurate is by using Project + Add Reference and select the DLL. If that doesn't draw any complaint and the assembly gets added to the References node of your C# project then you know it is a normal .NET assembly. Don't forget to take advantage of that, no pinvoke required.
Load the dll at runtime and use reflection to call it's methods.
Assembly assembly = Assembly.LoadFrom("C:\\test.dll");
Assembly.GetTypes();
Activator.CreateInstance(type);
I don't think it is possible to configure your program to use 1.2.* version and no others. Unless you would write the code for that on your own. Another possibility would be not to change the version tag of the C++ dll, but it does not seem you want to that.
A solution avoiding the version dependency would be the usage of dllimport. You can load any dll written in C++ with it. It is free of version dependency. See the example from the msdn and link at the end:
using System;
using System.Runtime.InteropServices;
class Example
{
// Use DllImport to import the Win32 MessageBox function.
[DllImport("user32.dll", CharSet = CharSet.Unicode)]
public static extern int MessageBox(IntPtr hWnd, String text, String caption, uint type);
static void Main()
{
// Call the MessageBox function using platform invoke.
MessageBox(new IntPtr(0), "Hello World!", "Hello Dialog", 0);
}
}
Description in MSDN
I have several Unmanaged C++ written lib files which I need to link to Managed C++ dll.
Then I need to invoke functions of this Managed C++ from C# application.
First step is OK - Managed C++ dll is created, I can see with ildasm that it exports functions I need. However when I try to call this function from my C#-written test app it says:
An unhandled exception of type 'System.IO.FileLoadException' occurred in Unknown Module.
A procedure imported by {MyManagedCPP.dll} could not be loaded.
This message goes from VS2010.
I made simple experiment - removed dependencies from all lib files in Managed C++ dll and rebuild it.
With this change it is OK - app starts, I can call functions of Managed C++ dll from C# test app.
Is it not possible by design to call managed c++ functions when dll has static linkage with lib files? Technical restriction? Or there is some workaround?
Thanks
You no doubt have an implicit dependency on a native DLL. It isn't clear from the question what DLL that might be. It could be msvcrxx.dll for example, a runtime support library for native C++ code. Which would be rather bad, you don't want to mix CRT versions. Such a missing DLL otherwise prevents the C++/CLI assembly from getting loaded, producing the FileLoadException.
If you have no idea what that DLL might be then you could use SysInternals' ProcMon utility. The trace will show you the program searching for the DLL and not finding it. If it is msvcrxx.dll then be sure to rebuild the .lib files using the same compiler version you used to build the C++/CLI assembly. If it is something else then make sure you copy that DLL to the build directory.
In my project I have an unmanaged native C++ dll and a C# application. I am trying to import a function from the unmanaged dll using DllImport but I keep getting a DllNotFoundException.
Here is my code that calls the DLL.
using System.Runtime.InteropServices;
namespace TestApp
{
public delegate void UpdateDelegate(string s);
class Program
{
[DllImport("CGPUnmanagedLibrary.dll")]
internal static extern int parse_raw_gsod_file(
[MarshalAs(UnmanagedType.LPStr)]
string filePath,
int minTemp,
UpdateDelegate callBack);
static void Main(string[] args)
{
UpdateDelegate myCallBack = new UpdateDelegate(Program.Report);
string path = #"C:\Creative Solutions\Projects\Clyde's Garden Planner\Frost Data Database\GSOD Data\GSOD_RAW_DATA\1992\gsod_1992.txt";
int result = parse_raw_gsod_file(path, 32, myCallBack);
Console.Write("Parse completed with exit code: " + result.ToString());
Console.ReadLine();
} // end main function
public static void Report(string msg)
{
Console.Write("Message is ");
Console.WriteLine(msg);
}
} // End class
} // end namespace
I tried copying the DLL to the app output directory but it still can't find it. I also tried adding the DLL project as a reference but I get a popup window saying it can't be added. How do you properly link an unmanged DLL to a managed application?
Update - Here is the full error:
Unable to load DLL 'CGPUnmanagedLibrary': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
Update 2 - I know for sure that the DLL is in the same directory as the .exe trying to load it. This makes me think there is a dependency in the DLL that isn't getting loaded. I'm only using basic C++ libraries in the DLL (string, math, iostream, etc). Any ideas what could not be loading and why?
Update 3 - Tested with Dependency Walker
Loading my unmanaged C++ DLL in dependency walker showed no errors. I also tried to open my executable in dependency walker and it showed errors loading two DLLs: GPSVC.DLL and IESHIMS.DLL - doesn't make any sense because I am only using standard c++ libraries in my code. I think it may have something to do with the fact that I have a managed C++/CLI DLL trying to load the unmanaged DLL as well (I was trying to implement some C++/CLI wrappers). Anyway, I have since started a new VS solution and moved on. See my answer.
In all likelihood the problem isn't the DLL you're trying to load but one of its (chained) dependencies. Run depends.exe or a similar utility on the DLL to see if all the dependencies can be found. The misleading message "The specified module could not be found" has become a classic annoyance (if not FAQ material!): it leads you to think that your DLL is not being found when almost all of the time it's one of its dependencies that's not being found.
To test, the *.dll needs to be in the same directory as the .exe that is trying to load it. Don't trust Visual Studio to do it for you at this point. Physically copy the file to C:******\Debug\x86\bin\ or whichever configuration you are running under. If in doubt, copy it to all of your bin folders. After you figure out the path, then you start finding ways to automate the project build to copy the file correctly. If that doesn't do it, put it in system32--it will certainly find it there. However, if after doing these things, you still can't find it. There is probably a dependency to your unmanaged dll that is also missing.
First I want to thank everyone for their help. Unfortunately I never did solve this issue (see edits in my main question). The answer turned out to be starting a totally new Visual Studio solution and creating two new projects: C# app and C++ dll. I did away with the need for wrappers as I am now just marshaling two main functions.
Thanks again.
The anwer of user arayq2 made much sense and I was quickly able to solve my problem also.
The dll that couldn't be loaded (DllNotFoundException) in my case is depending upon another dll. This dll (that is not part of my project) was actually compiled with newer versions of certain .h and .lib files. Older versions of these .h and .lib files (with the same filename) were part of the project that compiled the dll that couldn't be loaded.
After I updated my dll project with the newer versions of these .h and .lib files and recompiling my dll project, my problem was solved.
Thank you arayq2!
I have a Lua module (lpack) that I need to load into LuaInterface. I've tried a few different configurations for the project, but I can't seem to figure out the linking.
I get the error unresolved external symbol "void __stdcall lua_replace(struct lua_State *,int)" (?lua_replace##YGXPAUlua_State##H#Z) referenced in function "int __stdcall l_unpack(struct lua_State *)" (?l_unpack##YGHPAUlua_State###Z)
If I run dumpbin /exports on the lua51.lib file, I can find ?lua_replace##YAXPAUlua_State##H#Z which matches what I find in the lua51.dll with Dependency Walker ?lua_replace##YAXPAUlua_State##H#Z, so the function exists but the names don't match.
I'm not very familiar with this level of linker management, so this may be a simple error on my part. Why is the value in the lpack build not matching that of the lua51.lib input file?
Update
All of the exports in the lua51.dll and lua51.lib files were __cdecl and my lpack project has been set to __stdcall. Changing that property (under C/C++ -> Advanced -> Calling Convention) fixed the compile issue and I now have an lpack.dll file.
However, when I attempt to load the file from lua require('lpack') it fails with The specified procedure could not be found.
Breaking in the lua C code that loads the library with LoadLibraryA returns NULL and a GetLastError() code of 0x7F.
Update 2
The lpack.dll file I was attempting to load was out of date due to a wrong output directory, so that fixed the LoadLibrary failure. Next the GetProcAddress would fail, but if I added extern "C" to the export function in the lpack.c file as per Mud's recommendation, the problem was resolved.
However, when I attempt to load the file from lua require('lpack') it fails with The specified procedure could not be found.
Probably because the name is mangled. Did you look in the DLL to see the actual (mangled) name of the function?
You really ought to build the Lua source (and any Lua modules written in C) as C, and use extern "C" when importing them. Save you a lot of headaches.