In my VB .NET project, I have several functions that use unmanaged code from within winusb.dll. I tested the code on some machine which haven't drivers installed at all (winusb) and of course errors appears: "Unable to load winusb.dll...."
Now I don't want to try/catch every function imported since will drop performances (or not?) and instead, I'm thinking to use some check in my component constructor for presence of winusb.dll, raise error event and inhibit all functions until next program start. All functions are pointless without that dll. This is a good approach?
Now how can I check reliable for all platforms (xp, wista,7,8) for presence of that dll?
I need a expert opinion to optimum solve the problem and thanks very much in advance.
If System.IO.File.Exists("C:\Windows\System32\winusb.dll") Then
' go ahead
Else
' abort
End If
A better approach however would be to install the winusb library along with your application. An installer that doesn't install all required libraries is pretty worthless.
Related
I just converted one of the FsXaml demo programs to an interpreted F# script so I could experiment with it and learn. It wouldn't run, and the interpreter gave me the following error message:
System.NotSupportedException: The invoked member is not supported in a
dynamic assembly.
at System.Reflection.Emit.InternalAssemblyBuilder.GetManifestResourceStream(String
name)
at FsXaml.InjectXaml.from(String file, Object root)
at
FsXaml.App.InitializeComponent() at FsXaml.App..ctor()
at
FSI_0002.main[a](a argv)
in C:\Users\bobmc\OneDrive\FSharp\Learning\WPFExamples\FsXaml\demos\WpfSimpleMvvmApplication\WPFApp.fsx:line 104
at .$FSI_0002.main#() in
C:\Users\bobmc\OneDrive\FSharp\Learning\WPFExamples\FsXaml\demos\WpfSimpleMvvmApplication\WPFApp.fsx:line
109
Can I use the F# interpreter with FsXaml? Thanks to all for your help.
Unfortunately, WPF and scripts don't play well together.
The exception occurs within the WPF runtime itself - FsXaml.InjectXaml is using a XamlObjectWriter to populate the type with the contents from the XAML file. This type doesn't work if you're using a dynamic assembly (like FSI), which unfortunately means that FsXaml will likely never be able to work from FSI.
That being said, even if there was a way around this, it'd be of very limited use. WPF also has restrictions that make it not play well with a scripting scenario, such as the "only one application can ever be created within a given AppDomain" restriction. That one makes it so closing the "main" (first) window makes it so you can never open another one. As such, I haven't prioritized trying to make this work in FSI.
I'd be happy to accept contributions if somebody has an idea of how to make FsXaml play more nicely within the context of FSI, but at this point, I don't see a good solution for that usage scenario.
Edit: FsXaml 3.1.6 now includes functionality to make this a lot easier. It works well, provided you don't close the main window, or you use dialogs. There is a demo application/script illustrating this.
I'm trying to recreate a program that uses javascript to open a connection to a PLC and then display all sorts of information on a web page. I'd rather have it in a form in MS Access for various reasons, and have spent forever trying to find the right dll to use (Jet32X.dll, if anyone is curious). I finally tracked the CLSID called out in the javascript back to a registered class for the PLC, and I'm trying to create that object in VB code. It won't get any further than the Dim As New line, however, throwing runtime error 429: "Active X Component Cannot Create Object." Really wish I had some more information about why.
I know the class is registered, since that's how I found it in the first place. I know the DLL file isn't corrupted, since the program runs fine from the JS version. I have a sneaky suspicion that there's some sort of incompatibility going on here, since the PLC and supporting software is pretty old, and I'm working in Microsoft Access 2013 (and its associated VBA). I can't really think of a good way to verify this, however. Does anyone have any other ideas? Could anything else be causing this problem?
Figured it out; in case anyone else runs into this sort of issue:
32bit COM dlls will not run in 64bit applications. If you don't want to go back and reinstall 32bit versions of whichever application you're using, one of the easiest workarounds is using dllhost.exe as a surrogate.
You can read a little about it here, but I found this tutorial easier to follow.
I send a new reply just to recap the information and avoid anyone that stumbles in the same problem again after me wasting precious time. All the steps involved assume that you already correctly registered the dll you are trying to use.
How to make a 32bit COM Dll work in a 64bit application
The "easy" solutions involve using the Dll Surrogate method, which runs dllhost.exe and as an intermediary process in 64bit to expose the underlying 32bit dll. When done correctly this works seamlessly without any special measure needing to be taken in neither in the 32bit dll nor in the 64bit application.
There are two main approaches to this:
Using Oleview.exe (i.e. using a GUI)
Oleview can be obtained downloading the Window 10 SDK.
In order to use Oleview it you have to:
Download the Window 10 SDK at the following link:
https://developer.microsoft.com/en-us/windows/downloads/windows-sdk/
Go to C:\Program Files (x86)\Windows Kits\10\bin\10.0.19041.0\x86 to find the 32bit version of oleview.exe
ONLY THE FIRST TIME: run it as administrator to avoid see the message related to the impossibility to load iviewer.dll
In the left pane, Object Classes -> All Objects and find your dll name.
WARNING: you may find many entries for your dll. In particular each class has got its own entry such as YourProjectName.YourClassName
In the right pane, go to Implementation -> Inproc Server, and tick Use Surrogate Process. Leave the Path to Custom Surrogate empty to use the system default surrogate, that is dllhost.exe.
You can check the procedure went correctly by returning to the Registry tab, always in the right pane of the Oleviewer and make sure that now under CLSID = {yourAppIdHere} [DllSurrogate] = is listed among the entries.
Edit manually the Windows Registry
The Oleview method is recommended, but the manual method may be ok if you need to do this only once. The tutorial that NickGlowsinDark mentions was moved to https://techtalk.gfi.com/32bit-object-64bit-environment/ .
In order to avoid problems in the future with the page going offline I copy and paste here the most important steps involved. All credit goes to Emmanuel Carabott that is the original author of the tutorial, I added the first two steps in order to facilitate you in the process.
Open the Registry Editor (Windows+R -> regedit), and follow the following steps:
You first need to find your dll GUIDs. You will probably have many GUIDs, one for each of the classes that your dll exports. I find it's easier to find the GUIDs if you go to HKEY_CLASSES_ROOT\YourProjectName.YouClassName. It is the (Default) String Value you find under the Clsid key.
I recommend you find all the GUIDs first and make a note of them in order to have an easier time with the steps after this one.
Then, as Emmanuel Carabott kindly explains in his article, you have to do the following for each of the GUIDs you found:
Locate your COM object GUID under the HKey_Classes_Root\Wow6432Node\CLSID\[GUID]
Once located add a new REG_SZ (string) Value. Name should be AppID and data should be the same COM object GUID you have just searched for.
Add a new key under HKey_Classes_Root\Wow6432Node\AppID\
The new key should be called the same as the com object GUID
Under the new key you just added, add a new REG_SZ (string) Value, and call it DllSurrogate. Leave the value empty.
Create a new Key under HKey_Local_Machine\Software\Classes\AppID\
Again the new key should be called the same as the COM object’s GUID. No values are necessary to be added under this key.
That’s it, your COM Object should now be accessible from a 64bit environment and can be used like a regular COM Object.
I'm putting together a dll for use with MQL4 using nugent and vb.net and it's going pretty good so far.
In my dll I am setting a flag when a condition is met so that I don't have to keep checking each time the function is called. This works fine but what I realize it that the flag is remaining set and in memory even if I remove the EA that created the dll from the chart.
The flag is declared within a function in the module as static.
If I close the terminal and then open it again the flag has gone and the process starts again.
How can I remove the dll from memory and release it's resources (the static variable) on removal of the EA?
I'm thinking it should maybe call a function in the deinit but I can't find any VB.net examples of a dll 'killing' itself.
Any ideas would be much appreciated.
Steve
Update: I just had a thought. Maybe the dll is not supposed to end on removal of the EA from the chart? Could it be like that by design? If so I can just set the flag to false manually I guess.
But wouldn't that mean that if I add the EA to the chart again there will be another instance of the dll?
If anybody has a definitive answer though that would be great.
DLLs to be used in MQL4 expose functions that can extend the functionality offered by MT4. From what i understand about DLLs, they DO NOT offer data retention. Like, in your case, when you call a function of the DLL in your MT4 code, the data is retained for the duration of that call. When you restart the EA, the data is gone and everything is back to default values.
Hope this helps.
I want to implement a Webbrowser in my vb.net (2008)-project, however, I don't like the inbuilt IE.
I also remembered that is was kind of easy to implement a mozilla-tool like the gecko-webbrowser in the past...
It was kinf of more complicated than I remember, as I had to dwnload xulrunner and Skybound.Gecko.dll which both probably have to be included in any publishing of the finished project... I also defined x86 as target CPU and made all the needed steps to use a GeckoWebBrowser within my Application. I also called Skybound.Gecko.Xpcom.Initialize(My.Application.Info.DirectoryPath & "/xulrunner") before compiling it.
However, when I try GeckoWebBrowser1.navigate("http://...") (The element was inserted with this name per designer) the IDE tells me that an objectreference is not set to a objectinstance as if GeckoWebBrowser1 isn't defined yet... but the GeckoWebBrowser1.Created attribute is giving back true.
Does anybody know why it isn't working yet?
I have the same error in my solution. Try to use GeckoFX assembly. I use 15 version dll and error fix.
https://bitbucket.org/geckofx/geckofx-16.0/downloads
In short: I want to monitor selected calls from an application to a DLL.
We have an old VB6 application for which we lost the source code (the company wasn't using source control back then..). This application uses a 3rd party DLL.
I want to use this DLL in a new C++ application. Unfortunately the DLL API is only partially documented, so I don't know how to call some functions. I do have the functions signature.
Since the VB6 application uses this DLL, I want to see how it calls several functions. So far I've tried or looked at -
APIHijack - requires me to write C++ code for each function. Since I only need to log the values, it seems like an overkill.
EasyHook - same as 1, but allows writing in the code in .NET language.
OllyDbg with uHooker - I still have to write code for each function, this time in Python. Also, I have to do many conversions in Python using the struct module, since most functions pass values using pointers.
Since I only need to log functions parameters I want a simple solution. Is there any automated tool, for which I could tell which functions to monitor and their signature, and then get a detailed log file?
A "static" solution (in the sense it can capture a stack trace on demand) would be Process Monitor.
A more dynamic solution would be ApiMonitor, but it may be too old to be compatible with the applications to monitor. Worth a try though.
Some more Google searching found what I was looking for: WinAPIOverride32. It allows writing text files such as:
CustomApi.dll|void NameOfFunction(long param1, double& param2);
Later on, these files can be used inside the program to log all calls to NameOfFunction. Now I just need to figure out how to log arrays and structs parameters.
Visual Studio Addin Runtime Flow here:
Runtime Flow in real time monitors and logs function calls and
function parameters in your running .NET application and shows a stack
trace tree. No instrumentation or source code required for monitoring.
If you just want to see the function interfaces of the DLL, you could try "Dependecies" (https://lucasg.github.io/Dependencies/). This is a nice remake of the DependencyWalker in as OpenSource.
This only allows you to see the dependencies of the DLL, with the corresponding function names (however, not the calling structure). Unfortunately, I don't believe it will tell you which specific functions in a DLL are being used by the calling DLL/EXE.