Spying processes

I've to write a Win32 program that,given a file,tells me what process uses it...tricky uh?

Perhaps i could use a cicle like this :

Code:

 for(..some condition..){
  
     LockFileEx(handle to the file to control, ...... , ... , ..... , ... );
   
     Use GetLastError() and FormatMessage() for checking if an     error has occured
   and,if it is so,then some other process is reading the file and the 
   FormatMessage() function will tell me information about that process (i think)
   if i call it with the error code returned by GetLastError()

   Otherwise , if there's no error , UnlockFileEx(.....);

}

could it work?

I dont get what you want to do are you trying to check to see if a process is allready running?

Originally Posted by Lionel

could it work?

No GetLastError just returns an error code and FormatMessage traslates that error code into a desription of that error but
dosen't give anymore specific information.
Doing this would be tricky maybe the tool filemon from systeminternals.com might be of some use.

You could do this by hooking the API functions OpenFile(), CreateFileA(), and CreateFileW(). Hooking API functions is pretty tricky though, so I suggest finding another way around the problem you are facing.

You can get the processes that have a file open but I think you're moving into the undocumented.

Sounds a bit like you're trying to write (part of) http://www.sysinternals.com/ntw2k/fr.../procexp.shtml