api - Windows: How do I get the mode/access rights of an already opened file?

Question

I am writing a program that is using a database library. The library provides me access to the file handle it uses to access my table. I've found a windows API that allows me to retrieve information about the file by handle but I've yet to find any means of determining access mode / permissions of that file. At this point I'm sure I could likely live without knowing this information but being the stubborn cuss that I am I'm not ready to let this one go. Obviously Windows knows this info - so the question is how can coax the info out of it?

The API function that I've found is: GetFileInformationByHandleEx and it takes me close to the watering hole but doesn't let me drink the water.

The reason that the file mode information is useful is that I need to modify the table header information. If the file is already in a proper mode then I won't have to close the table open the file modify the file close the file then re-open the table.

And yes, before I'm told of all the options available to me to achieve my goal - I'm not interested in those. I'm only interesting in the original question - how do I determine the mode of an already opened file. I look forward to any responses and I thank you in advance.

Thanks, Robert Milligan

Answer 1

I don't know if there is a corresponding Win32 API for this, but if you really need it you can call NtQueryObject(ObjectBasicInformation).