Using C#, how does one figure out what process locked a file?

Question

In Windows, how do I determine (using C#) what process locked a file?

Third-party tools are helpful, but not what I\'m looking for.

Answer 1

Not very straightforward, but on Windows Vista and above you can use the Restart Manager APIs to see who is using a file. Internet Explorer caches settings includes details on using this to detect which process has iexplore.exe open.

Omitting a lot of detail:

// Start an RM session
RmStartSession(&sessionHandle, 0, sessionKey);

// Register the file you are checking
RmRegisterResources(sessionHandle, 1, filePathArray, 0, NULL, 0, NULL);

// Get all processes that have that file open.
RmGetList(sessionHAndle, &nProcInfoNeeded, &nProcInfo, processes, &rebootReason);
RmEndSession(sessionHandle);