What Win32 API can be used to find the process that has a given file open?

Question

If I read or write to a file and receive a 33 or 32 error, I would like to log a message containing the name of the other process(es) that have the file opened. There must be a Win32 API I could use to get this info. Process Explorer displays it. Of course, Process Explorer also has info about all processes in memory. I'd prefer to find the culprit without interrogating all processes.

Answer 1

The Handle program from SysInternals does this as well, but I'm not sure how. I don't think there is a single documented API to do this. I think you have to iterate over the processes, enumerate each of the handles in the process, and then determine the filename associated with that handle.

Answer 2

As of Windows Vista, the Restart Manager can be used to determine which process(es) have a file open.

This page has sample code: https://devblogs.microsoft.com/oldnewthing/20120217-00/?p=8283

From that page, the steps (for the sample code) are the following:

1. Create a Restart Manager session.
2. Add a file resource to the session.
3. Ask for a list of all processes affected by that resource.
4. Print some information about each process.
5. Close the session.

Here is the documentation for the Restart Manager: https://learn.microsoft.com/en-us/windows/win32/rstmgr/restart-manager-portal