+
+ local fp = io.open(filename)
+ if not fp then
+ return nil
+ end
+
+ local output = {}
+ local sink = ltn12.sink.table(output)
+ local source = ltn12.source.chain(ltn12.source.file(fp), mime.encode("base64"))
+ return ltn12.pump.all(source, sink) and table.concat(output)