Determine if a file is open

Question

Is there any way to determine if a file is open by anything include applications that do not lock the file (like notepad).

I need to detect when a given file myfile.txt is no longer open in any application including notepad - so i cannot use File.Open(...) with exclusive access to test since the file has no lock on it.

Answer 1

http://stackoverflow.com/questions/177146/how-do-i-get-the-list-of-open-file-handles-by-process-in-c

Answer 2

You must call File.Open(...) specifying your desired access flags and check the returning value to determine if the file is opened or if the access is denied. This is the recommended and safe way to access a file.

Answer 3

No. When Notepad has opened a file, it has read the entire file in and then closed it. So there is no trace in the OS that links Notepad's private memory with the file on disk.

Opening the file exclusively will not work, because Notepad does not have the file open. Searching Notepad's handle table will not work, because Notepad does not have the file open.

The only way to detect this is to write an unmanaged DLL that is injected into every process to scan their virtual memory, searching for the exact file contents. Not recommended.