I've added a new library to my application (multiple projects-DLLs) - SQLite, to perform some in memory caching. There is just one library/project that is affected by this change - Lib1.
A build goes through fine. All libraries are built successfully and no errors are reported, including a couple of Com Objects.
If I try to register the com objects, I get the The DLL could not be loaded. Check to make sure all required application runtime files and other dependent DLLs are available in the component DLL's directory or the system path. message. But all the libs are at the same place. And all are in the path. A copy of this project builds and registers fine (without the few changes made for SqlLite ofcourse). Dependency walker reports no issues
Oddly, if I try to register the DLL of the com object (using regsvr32) it works fine. Also, I have another library, which is dependant on Lib1 (not on SqlLite) which also cannot be loaded.
Any ideas?
Thanks,
A'z
You can use Process Monitor (http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx) set to filter process name regsvr32.exe in order to see all file and registry access.
Always use full path to your-com-dll when you issue regsvr32 commands, if you have the same dll somewhere else in path (for example c:\windows\system32) regsvr32 will use the other dll and not the one in your current directory.
Another trick would be to use "rundll32 your-com-dll,DllRegisterServer". In case of missing dlls it will tell which dll is missing instead of just saying that LoadLibrary failed.
Edit:
What do you mean by "If I try to register the com objects"? How are you doing this? I'm asking because you say that regsvr32 on the dll which actually implements these com object works fine.
Use the dependency walker tool to figure out what other dlls the COM server relies on. Then check the executable paths that is set in Visual Studio (Tools -> Options -> Projects -> Directories (I think)). Note that VS does not use the system PATH environment variable - it uses what is set in the options page so if the path to the dependencies is not listed there, the registration would fail, even though if you used regsvr32 from the command line it would succeed.
And so, the plot thickens!!!!
I've actually narrowed down the to the line of code that causes this linking problem.
In the modified library (LIB1) I've added a new class A1 which inherits from an existing class A.
When I change an existing class B which used to inherit from A to now inherit from A1 - this is when the problem is caused. Class B is in a lib3.
I've verified that just when I change the inheritance, only then the problem occurs!!!
I've used file-mon on regsvr32 when loading successfully and when failing. I stuggle to find the difference! Tomorrow morning I'll try Process Monitor and see if it helps.
Still desperate for help,
A'z
hmm... as Christian asks, how else are you attempting to register the objects if regsvr32.exe succeeds?
the rundll32.exe advice is also good. have you tried stepping through DllRegisterServer in a debugger to see precisely when it's failing? this sounds like a potential runtime failure if depends.exe isn't revealing anything.
btw, when i google for that exact error text i see: http://social.msdn.microsoft.com/forums/en-US/sqldataaccess/thread/402c1767-cf1d-42f0-aec9-e0169dbf1083/, but I assume you've probably already done this search and found it not helpful :)
Related
I am currently trying to basically expose a native C++ library, that I not have the code for, as a WebApi. To do that, I created a managed C++ wrapper library, that allows my web application to communicate with the native code.
So the dependencies of the project look something like this:
Web application (ASP.NET)
Managed C++ Wrapper
Native C++ Library (DLL)
Native Dependencies (DLLs)
My problem is now, that I always get the error message "Could not load file or assembly [ManagedWrapper.dll] or one of its dependencies. The specified module could not be found."
Since the managed wrapper library is in the same solution, it is listed as reference and even copied to the shadow copies, so I assume that the problem lies in the native dependencies. I am well aware that there are problems with loading native DLLs in ASP.NET as no shadow copies will be made of them and they can not be added to the GAC. I tried to tackle this problem by just adding them to my %PATH%, but the error still remains. Dependency walker did not show any additional dependencies and adding the native DLLs to system32/inetsvr fixed the problem, but this is obviously not the way this should be done.
So here my question: What could be the reason that the PATH variable is not working? (And is there maybe another way to get this to work?)
Using loadLibrary to load with an absolute path is not really a possible solution as I have no influence on the native C++ library and how it will load further dependencies.
I think I found my own a solution to my problem and hope this might help someone else as well:
My native DLLs where somewhere in my home folder. Moving them to a more accessible place, i.e. C:\temp\, and adding this folder to the path seemed to do the trick. My guess is, that this was a permission based problem, even though I added rights for IUSR for that folder in my home directory before.
I've been making a program in Visual Studio 2012, what comes with it is that when I send my application to someone, they need the VS2012 Runtime, which sometimes they don't know where to download or what they need (for normal users "xxx.dll is missing" is very misleading).
I know exactly which dependencies my application requires (fantom.dll [Lego Mindstorms stuff] and the VC++ 2012 Redist).
I would like to show a dialog when these libraries are missing on application startup and provide the user with download links for these libraries.
Is this possible to accomplish?
Yeah you could do something like:
Move all of the code in your binary into a DLL.
Create an EXE which dynamically loads the DLL using LoadLibrary and unloads it with FreeLibrary.
If LoadLibrary fails, check if its due to missing DLLs, if so then display a MessageBox/your custom message and exit.
Of course this means your EXE project must NOT depend on the runtime itself - this shouldn't be an issue since you'll only need to call 3 win32 API's.
No it's not possible but you can create an installer for your program. The error is thrown during the loading of your program, before your code execution...
You can try with that : http://www.codeproject.com/Articles/24187/Creating-an-Installer
I can't speak for testing the VS2012 Runtime dynamically, but you can certainly validate fantom.dll dynamically. Instead of static-linking to the DLL directly, you can dynamically load it instead. You can configure your project to delay-load the DLL at run-time, and then provide a delay-load callback handler that the RTL will call if the delay-load fails. Or you can simply skip the delay-load feature and load the DLL yourself manually by calling LoadLibrary() and GetProcAddress() directly.
Sure, you can verify if a dependency exists on the deployed system. A few things come to mind...
You can see if the assembly is recognized on the running system by calling AppDomain.AssemblyResolve() . Further reading here
Another more primitive option is to call a File.Exists(your assembly path here) test, but I would advise against this as it's a bad practice to require hard-pathed installation locations.
That said, and as others have stated, it's still by far the best approach to create yourself an installation distribution.
My basic issue is this: my program (MyProgram.exe) has a dependency on a DLL from another program (OtherProgram), and I'm trying to avoid repackaging a new DLL every time OtherProgram updates. I'd like to have MyProgram.exe link in OtherProgram's DLL when it launches, but I'm not completely sure that Windows allows for this. So if there is some kind of workaround that would also be acceptable.
And just for some background, the platform is Windows 7 x64, and MyProgram.exe runs fine when I create a symlink in the MyProgram.exe project directory to the DLL in OtherProgram's install directory. When I try to run it without the symlink, I get the "program can't start because OtherProgramDLL.dll is missing from your computer" error.
Any advice or links to relevant info is greatly appreciated!
EDIT: Clarification: the DLL is not linked at compile-time, this issue crops up at runtime
There are two types of dynamic linking in the Windows world:
Load-Time linking is when a DLL is loaded automatically when your program starts up. Windows finds this DLL using a specific algorithm I'll discuss below.
Run-Time linking is when you specifically load a DLL by calling LoadLibrary in your code. Similar rules apply as to how the library is found, but you can specify a fully-qualified or relatively-qualified path to control the search.
In the case of Load-Time linking, MS recommends that your program's DLLs are stored in and loaded from the same directory where your application is loaded from. If this is at all workable, this is probably your best option.
If that doesn't work, there are several other options, outlined here. One is to leverage the search order by putting the DLL in either the working directory or the directory where the application was loaded from.
You can change the working directory of an application by:
Create a shortcut to your application.
Bring up the shortcut's properties
Edit the "Start in" property with the directory where the DLL is located.
When you launch your application using the shortcut, it will load the right DLL.
Other options for load-time linking include:
Adding a manifest to your application which specifies where your dependent assemblies are, or,
Setting the PATH.
You could use LoadLibrary, but you would need a way to guarantee the DLL's location. This Wikipedia article provides good example on how to use the DLL after it has been loaded.
You can add the directory where the dll is located to the PATH environment variable.
I have struggled with the same problem and also found a dead end with the suggested methods like LoadLibrary, SetDllDirectory, Qt's addLibraryPath and others. Regardless of what I tried, the problem still remained that the application checked the libraries (and didn't find them) before actually running the code, so any code solution was bound to fail.
I almost got desperate, but then discovered an extremely easy approach which might also be helpful in cases like yours: Use a batch file! (or a similar loader before the actual application)
A Windows batch file for such a purpose could look like this:
#echo off
PATH=%PATH%;<PATH_TO_YOUR_LIB>
<PATH_TO_YOUR_APP_EXE>
/edit: Just saw #SirDarius comment in Luchian's answer which describes that way, so just take my batch code bit as a reference and all credits go to him.
I have the same problem with one application I am working on.
I do not want to use runtime loading because there are tens of functions I would need to manually create function pointer for.
Mr Dibling's mention of manifest file opened a new door for me but I sadly found out that the oldest version of windows that supports the feature is Windows 7. It won't even work on Vista.
Long story short, a friend familiar with Windows Application development told me to look up Delay-Loaded DLL, which turns out to solve the problem perfectly with minimal effort. It delays the loading of DLL library to either the point you manually do, or the first time its function is called. So you just need to add your DLL path to the search path before that happens, where SetDllDirectory helps.
Here is the steps to make it work:
1) Specify the DLL to be delay-loaded to linker, either through your makefile, cmake or VS property page (Linker->Input of VS2015)
2) Call SetDllDirectory at the beginning of your program, before any call to the DLL is made.
Delay-loaded DLL is supported all the way back to VC6.
SetDllDirectory is supported after XP SP1.
Use Symbolic Links to the 3rd Party Executables
I found the approach advocated by Aaron Margosis useful. See:
Using NTFS Junctions to Fix Application Compatibility Issues on 64-bit Editions of Windows
Essentially, create symbolic links to each of the dependent 3rd Party executables. Place these symbolic link files in and amongst your own dependent executable files. Except for filename changes to the targets, the 'soft' symbolic links will resolve the load-time dependencies even as the target of the links are changed by future updates.
I am working on a Qt DLL that is used as a plugin for a large application. This DLL depends on other DLLs that are sadly not located in the same folder and hence will only load if the current working directory has been set correctly (which the large application does prior to calling LoadLibrary on the DLL). I have no control over this behaviour.
I have been asked to add a simple COM object to this plugin which I have done but I now have the problem that the DLL cannot be registered or used by a 3rd-party application unless the current working directory is set correctly - because any LoadLibrary calls on the plugin fail due to the missing dependencies. Obviously I have no control over the current working directory used by 3rd-party apps and at this stage I am not allowed to modify the PATH to ensure the dependencies can be found.
I have tried using /DELAYLOAD for the dependent DLLs but this fails with 'cannot delay-load foo.dll due to import of data symbol...' errors. Again, I cannot easily change the way these dependent DLLs are used.
Currently I think the only solution is to move the COM object into a stand-alone DLL that doesn't depend on anything else but I am under pressure to find a solution and leave the COM object in the plugin DLL. I can't see how this is possible so I thought I'd see if anyone else has any ideas. Some form of system-wide SetDllDirectory call would help or some registry hack that could set the working directory when a 3rd-party app calls LoadLibrary on my plugin.
IMO separating the COM object into a separate .dll is the cleanest solution - anyone would expect an in-proc COM server to be registered by using regsvr32 and that requires no fancy dependencies in that COM server.
I don't know if it's precisely a solution to your problem, but maybe this can help you: try to look at the possibilities offered by manifest files. I hope it will help.
You could use a runtime registration model.
The Dll could register itself as a COM server in its own initialisation code.
This only requires that loadlibrary is guaranteed to be called before the dll is used as a COM server.
I am building a project in VS2005 and several of my DLLs are failing to register. The error message I am getting in Visual Studio is:
Project : error PRJ0019: A tool returned an error code from "Registering ActiveX Control..."
which is nicely vague. When I register the DLL manually through the command line (using regsv32.exe, I get the following error:
LoadLibrary("test.ocx") failed - This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix the problem.
I ran Dependency Walker (depends.exe) on the culprit .ocx file but it isn't showing any obvious problems.
I have also done a re-build but I'm still getting the same problem.
Any suggestions as to how I could determine the cause of this failure to register?
Microsoft had recently released a Security Update for ATL (KB971090). It is un update on top of MSVS2005sp1 and it's both compilate-time and runtime compatibility breaker. Check if your building environment has this patch.
References:
ATL Security Update:
http://msdn.microsoft.com/en-us/visualc/ee309358.aspx
Breaking changes in ATL:
http://msdn.microsoft.com/de-de/library/ms235654.aspx
And this is a must read:
http://tedwvc.wordpress.com/2009/08/10/avoiding-problems-with-vc2005-sp1-security-update-kb971090/
Most probable is because the embedded manifests. You should take a resource explorer application and check your DLLs for the embedded manifests. It might be that one of the dependent DLLs (or your DLL) require some versions of other DLLs which don't exists.
I got this message: "This application has failed to start because the application configuration is incorrect." in case of embedded manifest mistmatches.
Probably the easiest way to troubleshoot this whole category of problem is to install Process Monitor from microsoft.com.
Process Montior lets you observe the system calls processes are making, and in this case you will be able to see if some system call is failing. For example, if you are lacking a dependency, then a CreateFile() call will be seen failing with a DLL, OCX, etc. as the filename.
Launch procmon and configure the filter to exclude events other than from regsvr32.exe, reproduce your test case, and then check the log. Look for NAME_NOT_FOUND errors in the return value column.
Do you have the C++ Redistributable Package Installed?
There are several things you can try:
try regsvr32 w/ fusion log enabled (fuslogvw.exe - it works for unmanaged dlls as well). This would give you a bit more information than depends on what external dependencies are loaded, where are they loaded from and what errors were hit.
copy the .ocx and its dependencies to the root or a first level folder and try registering from there. I don't remember details, but there was an old problem with registering a COM dll from within too deep of a path.
run regsvr32 under WinDbg. Set a breakpoint DllMain and see if it does anything funky.
If you never break on DllMain in WinDbg, set a breakpoint on module load for your dll and once it's hit, you can either step through LoadLibrary, or just set a generic load library breakpoint and check every dll after that.