dos2unix.lua

local BLOCK_SIZE = 4096

-- Internal: Open the file or die
-- External users should catch the error if they wish
local function openordie(filename, mode)
	handle, err = io.open(filename, mode)
	if err then
		error(err)
	end
	return handle
end

-- Process the provided filename from opening it by its name until writing out
-- the new version. Also overwrite the original if in_place is true.
local function dos2unix_end2end(filename, in_place)
	local filename_new = filename.. ".new"
	infile = openordie(filename, "rb")
	outfile = openordie(filename..".new", "wb")
	dos2unix_handle(infile, outfile)
	infile:close()
	outfile:close()
	if in_place then
		os.remove(filename)
		os.rename(filename_new, filename)
	end
end

local function dos2unix_handle_inplace(infile)
	local scratch = io.tmpfile()
	-- TODO: remove all \r\n, write to tmpfile,

	-- TODO: write tmpfile over infile

	-- TODO: write \n\0* over the rest

	-- rewind
	dos2unix_handle(infile, scratch)
end

-- Rewind the provided handle, process it, then rewind it again
local function dos2unix_handle(infile, outfile)
	infile:seek("set", 0)
	repeat
		inbuf = infile:read(BLOCK_SIZE)
		outbuf = string.gsub(inbuf, "\r\n", "\n")
		outfile:write(outbuf)
		io.stderr:write("#inbuf="..tostring(#inbuf))
		io.stderr:write("\n")
	until #inbuf < BLOCK_SIZE
	infile:seek("set", 0)
end

-- STANDALONE PROGRAM CODE BELOW
if not (minetest and minetest.get_modpath("serialize_lib")) then
	local function ipairs_offset(t, off)
		local size = #t
		local f = function(t, idx)
			if idx >= size then
				return nil
			else
				return idx+1, t[idx+1]
			end
		end
		return f, t, tonumber(off-1)
	end

	local in_place = false
	if arg[1] == "-i" then
		in_place = true
	end

	for k,v in ipairs_offset(arg, 1+(in_place and 1 or 0)) do
		dos2unix_end2end(v, in_place)
	end
end

return {
	dos2unix_end2end = dos2unix_end2end,
	dos2unix_handle = dos2unix_handle,
}