Accessing config.ini from a mod

[Vulcan]

I want to access config.ini in Factorio's user data directory. I have a Lua library that reads the .ini file, but I don't know what file path to use to get to config, as this requires going up two levels to the user data directory and then to config/config.ini.
How would I achieve this? I use Windows, but I would like a solution that's cross-platform if at all possible.

Thanks in advance

[prg]

You can't read arbitrary files from a user's system, even if you knew the path.

[Vulcan]

That's disappointing. Why is this not possible?
The next step would be to ask how to access key binding information in game, presumably the data is there somewhere