Provide a function to voluntarily set the writable directory to either the user's save directory, or the executable's source directory (when fused) in löve. (0.9.1+) P.S.: Probably unsafe/useless on linux.

writablesource.lua

local ffi = require "ffi"
local liblove = ffi.os == "Windows" and ffi.load "love" or ffi.C

ffi.cdef[[
	int PHYSFS_setWriteDir(const char* newDir);
]] -- This call will fail (and fail to change the write dir) if the current write dir still has files open in it.

local usrPath = love.filesystem.getSaveDirectory()
local srcPath = love.filesystem.getSourceBaseDirectory()
local dir = 'usr'

local t = {}

t.getCurrentWriteDirectory = function()
	return dir	
end

t.setCurrentWriteDirectory = function(d)
	assert(string.lower(d) == 'usr' or string.lower(d) == 'src',"The given parameter is not accepted!")
	if dir == d then return true end
	dir = d
	local success
	if dir == 'usr' then
		success = liblove.PHYSFS_setWriteDir(usrPath)
	elseif dir == 'src' then
		if not love.filesystem.isFused() then error "Can't set the write directory to the source; The game is not fused!" end
		success = liblove.PHYSFS_setWriteDir(srcPath)
	end
	return success ~= 0 and true or false,success
end

return t