Finding a MIME type for a file on windows

Question

Is there a way to get a file's MIME type using some system call on Windows? I'm writing an IIS extension in C++, so it must be callable from C++, and I do have access to IIS if there is some functionality exposed. Obviously, IIS itself must be able to do this, but my googling has been unable to find out how. I did find this .net related question here on SO, but that doesn't give me much hope (as neither a good solution nor a C++ solution is mentioned there).

I need it so I can serve up dynamic files using the appropriate content type from my app. My plan is to first consult a list of MIME types within my app, then fall back to the system's MIME type listing (however that works; obviously it exists since it's how you associate files with programs). I only have a file extension to work with in some cases, but in other cases I may have an actual on-disk file to examine. Since these will not be user-uploaded files, I believe I can trust the extension and I'd prefer an extension-only lookup solution since it seems simpler and faster. Thanks!

Answer 1

HKEY_CLASSES_ROOT\\.<ext>\Content Type (where "ext" is the file extension) will normally hold the MIME type.

Answer 2

In Windows 10, the different MIME types are stored in the registry at:

HKEY_CLASSES_ROOT\MIME\Database\Content Type

with a key for each content type (e. g. text/plain) under that key.