New filter scheme.

ltn12 and mime updated.
smtp/ftp broken.

etc/b64.lua

@@ -1,13 +1,12 @@
+local source = ltn12.source.file(io.stdin)
+local sink = ltn12.sink.file(io.stdout)
 local convert
 if arg and arg[1] == '-d' then
-    convert = socket.mime.decode("base64")
+    convert = mime.decode("base64")
 else
-    local base64 = socket.mime.encode("base64")
-    local wrap = socket.mime.wrap()
-    convert = socket.mime.chain(base64, wrap)
-end
-while 1 do
-    local chunk = io.read(4096)
-    io.write(convert(chunk))
-    if not chunk then break end
+    local base64 = mime.encode("base64")
+    local wrap = mime.wrap()
+    convert = ltn12.filter.chain(base64, wrap)
 end
+source = ltn12.source.chain(source, convert)
+ltn12.pump(source, sink)