"Hook" type program? 1

[Valius]

Have a thought provoking question. Let's say that I had a program that was using the registry and another program that read those values the first program was putting into the registry. Is there some way I can use a "hook" of sorts that I can setup so that I will know when something has changed in the registry? I don't want to use a timer..that's what I'm using now. Just some sort of way I can fire off a function when a certain value in the registry is changed. Thanks in advance!

Niky Williams
Lead Engineer
NTS Marketing, Inc.

 

[LiquidBinary]

I think a win32 hook would be overkill for this situation. Instead why not have the registry writting program communicate with the registry reading program after a key has been modified. After your data has been stored in the registry by your program, have it "send a message" to the program that will attempt to read it. This message hand off can be accomplished via a SendMessage() call. Windows provides a default program specific message called WM_USER. You can catch this message and respond to it.
After your window has written info. into the registry, you could do somthing like this ->

SendMessage( hReadRegistry,WM_USER,NULL,NULL );

Where hReadRegistry is the handle to your window that will attemp to extract information from the registry. Then just catch and respond to this message. Mike L.G.
mlg400@blazemail.com

 

[Valius]

Oh, now THAT is a cool idea. I never thought of doing that. I didn't even think it was possible to send messages between 2 seperate programs. Thanks for the awesome idea! Just out of curiosity, if I wanted to look into hooks, where would be a good place to start? I mean, just give me a few function names that are used and I can research them from there. Thanks again!

Niky Williams
Lead Engineer
NTS Marketing, Inc.

 

[LiquidBinary]

The raw win32 api contains some nice registry handling functions. To get you started, you might was to research the following api calls ->

LONG RegOpenKeyEx( HKEY hKey,LPCSTR pszSubKey,
DWORD NotUsed,REGSAM Access,
PHKEY Result );

LONG RegSetValueEx( HKEY hKey,LPCSTR lpszName,
DWORD NotUsed,DWORD DataType,
CONST LPBYTE lpValue,DWORD size );

LONG RegQueryValueEx( HKEY hKey,LPSTR lpszName,
LPDWORD NotUsed,LPDWORD DataType,
LPBYTE Value,LPDWORD SizeOfData ); Mike L.G.
mlg400@blazemail.com

 

[LiquidBinary]

Here are some functions that install hooks etc...made possible via the win32 api ->

HHOOK SetWindowsHookEx( int type,HOOKPROC HookFunc,
HINSTANCE hInst,DWORD ThreadID );

BOOL UnhookWindowsHookEx( HHOOK HookFunc );

LRESULT CallNextHookEx( HHOOK CurHook,int code,
WPARAM wParam,LPARAM lParam );

Mike L.G.
mlg400@blazemail.com

 

[Valius]

I am currently using those API calls. The program I'm doing right now is pure Win32 API. Currently I just have a timer checking the registry every once and a while so the program knows what to do...least it will be like that until I can implement the messaging system you proposed. Thanks again for the info!

Niky Williams
Lead Engineer
NTS Marketing, Inc.

 

[Valius]

Okay, I can run from there with those functions that install hooks. Probably won't be doing too much with them now that I know I can use messages. Thanks again for your help!

Niky Williams
Lead Engineer
NTS Marketing, Inc