love.filesystem.getSourceBaseDirectory
Returns the full path to the directory containing the .love file. If the game is fused to the LÖVE executable, then the directory containing the executable is returned.

If love.filesystem.isFused is true, the path returned by this function can be passed to love.filesystem.mount, which will make the directory containing the main game (e.g. C:\Program Files\coolgame\) readable by love.filesystem.
path = love.filesystem.getSourceBaseDirectory()
path string The full platform-dependent path of the directory containing the .love file.