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Could someone please show me an example of how to create a registry entry using an API call to advapi32.dll. Basically make it do what the below .NET statement does.
Registry.SetValue(@"HKEY_LOCAL_MACHINE\SOFTWARE\ABCsoft\System\INIT", "SHARELOCATION", "C");
I have heard it can be done but haven't found any sample code to illustrate syntax.
Thank you so much for your time!
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You're in luck: the essential registry functions reside in advapi32.dll
google for RegCreateKey, RegOpenKey, RegSetKeyValue
I stopped using most of them when .NET 2.0 started registry support.
Not sure why you want the trouble of finding the right combination and go through P/Invoke though.
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I need to use the API because I will be having the users run the app from a mapped network drive. And too many users encounter a security exception when doing this. And I don't have the ability to modify the .NET config tool settings. So I have to do it the old fashioned way. Just don't know how format the syntax for those functions. Thanks.
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OK, that is 2 issues:
1. running a networked app
for a .NET app, that could be an issue
2. accessing registry keys
I'm not convinced the old Win32 registry function would work when the .NET Registry class would prevent you from accessing the regkeys. And I expect it will be more strict on the latest Win versions (Vista, 7).
Are you saying you want to create a native app? didn't think so since you asked in this forum, C# is always managed and .NET
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Thanks for your reply. Because the default setting for .NET is to prohibit writing to the registry when being run from a mapped drive. And I can't change .NET settings. I'm being forced to call API's. I know the API and function to use. Just not sure on how to use it. I know this can be done because I've run across web pages Calling API functions using C# that show it. So no, I don't want a native app. Just a Managed one that ALSO uses non managed code. The closest I've come is this --> http://pinvoke.net/default.aspx/advapi32.RegSetValueEx[^] but I'm still lost even with it. Thanks
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I'm sorry to say but that article dates back 2001, it uses .NET 1.0 and AFAIK it's only reason of existence is .NET 1.0 did not have the Registry classes.
I doubt very much it will succeed in writing registry entries where normal .NET Registry classes (in existence since 2.0) would fail. However you can try that by downloading and running its code I guess.
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OK, Thanks Luc. I didn't notice the date. I'll have to come up with another idea. But thanks for all your help. 
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you're welcome.
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...with security issues like this though I can see why old timers are unwilling to try managed code.
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It all depends. Do you want any EXE on a network, when double-clicked to start running and potentially delete your disk's content, change your registry, etc.
Microsoft is finally taking major steps in increasing security:
- .NET has its default permissions set low for all but the local drives;
- Vista (and Win7) are much more strict on file system and registry access;
- etc.
It is about time, if you ask me.
And yes, there is some pain since we got used to the more/too relaxed situation that existed till now.
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Very good points. But yes, there is some pain. hehe.
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You could also go directly for ntdll.dll, if it doesn't work with that then it's a sign that what you are trying to do amounts to hacking 
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Hacking? Oh for Pete's sake. What I want to do is so simple. If I knew C++ I'd have it done already I'm sure. But I'm trying to do it in c#. I do tech support. I want to be able to send a single executable file to a customer so I can easily make program setting changes WITHOUT guiding them thru using REGEDIT. Because .NET wont let me make those changes when running from a mapped drive, where the program whos settings are I want to change, sits. People have been programming using Win32 API's for years! All I want to do is make one call to bypass .NETS security. In my opinion, much safer than using the .NET configuration tool to open up ALL registry access.
Sorry, I'm just frustrated. If there is an easier way to make that registry change, TRUST ME, I would love to hear it.
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you could use regsvr32.exe and feed it a .reg file
and you can automate that with a batch file or with the Process class.
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Thanks,I wish I could. But a lot of what I would need to change or set would be dependent on different paths the client may be using. It would defeat my purpose. Be easier to just remote in and make the changes myself.
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I don't understand, you could use a C# app to create a temporary .reg file and launch regsrv32 to execute it, couldn't you?
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Now THAT, is not a bad idea! I little more work than i planed but, great idea! THANKS! But isnt regsrv32 used to register DLL files?
modified on Friday, April 17, 2009 9:06 PM
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It started with a release build that failed to work.
Or actually it is a bit more subtle but it took a lot of work to find that out.
So, the story.
I'm writing a dll that is part of a bigger program. When I'm debugging it, it works fine, nothing wrong. But when I run the release build it first takes 100% cpu and after a while it crashes. This only happens if I run the release build - so neither when I try to debug the release build and ignore the warning that it's optimized, nor when I run the debug build directly without the debugger attached.
Have tried:
* copying the "debug" dll to the release folder of the exe (works)
* replacing all #if DEBUG by #if true (does not work)
* enabling full debug info for the release build (no effect)
* disabling optimization for the release build (works!)
But merely knowing this doesn't solve the problem. I'd like the code to be optimized.
So here is the real question: what is going on here? what could cause this?
I have a small amount of reflection going on, but nothing to serious, just things like enumerating custom attributes and calling a default ctor.. No dirty tricks with MSIL and Reflection.Emit. It does use SetWindowsHookExA but in a completely different part of the program than the failing part which shouldn't have any effect at all - but maybe it does? And it uses Xna.Framework and Xna.Framework.Game (but they should work, they always used to), which is why I'm compiling for x86 only (not AnyCPU).
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harold aptroot wrote: it first takes 100% cpu and after a while it crashes.
Is there any specific error when it crashes?
Are you running the release build on your development machine? If so, you should get the option to attach the debugger only at the point of failure if attaching it before that point somehow doesn't show the error.
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No it just goes unresponsive and windows asks me to close it.. I tried telling it to wait but it just goes on doing a lot of apparently nothing without any noticeable progress..
How do I attach the debugger to it? I remember seeing such an option in VC++, but I don't see it in VC# (I'm using Express now btw maybe that's why?)
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Hi Harold,
do you have multiple threads? and cheap synchronization, say a bool variable set by one thread, read by another? forgot to apply the volatile keyword correctly?
in general: check your loops for things that, by optimization, might be pulled out completely making the loop empty and spinning forever.
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A good suggestion and it was actually my first thought - but as far as I'm aware I only use ManualResetEvent's for synchronization, and that should work shouldn't it?
Mostly it just spawns a few threads and then waits for all of them to finish (not many, say 3 to 8, doing a couple of seconds of work) and BeginInvoke/EndInvoke for some smaller tasks
But I'll recheck everything
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The alternative problem situation is a race condition: say you start a very short thread and clear a flag (a bool or a ResetEvent) then wait for the flag getting set; whereas the right order would be clear the flag, start the thread, wait for the flag.
By optimizing stuff the thread becomes faster and may set the flag before you clear and then test it.
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Also nice suggestion, it's happening in this order: create and clear flag (new ManualResetEvent(false)), create (new Thread) and start thread, the thread runs and eventually sets the flag (Set() on the resetevent)
After starting all threads in this way it begins waiting for the threads.
Old ResetEvents are just discarded.
Is that right?
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That is right if executed once; and it may be right if inside a loop.
If both sides contain a loop and need to synchronize each iteration of it, then I consider it bad style to create new ResetEvents (or whatever synchronization object) all the time, since one party could be manipulating the old/new object whereas the other is manipulating the new/old object (which they probably share through a shared variable, say a class member) probably leading to a stand-still.
I would suggest you add some logging: let your threads report somehow what they are doing. I always have a protected void log(string s) method present in all my classes, it's implementation could be as simple as Console.WriteLine(s); or could be somewhat more complex, possibly with the current time, the current thread's ID, optional file output, etc.
Seeing the system-wide actions in chronological order helps in debugging, much more than breakpoints and other fancy stuff if you ask me. The Visual goodies are more suited for solving very local problems, once you now about where they are.
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