My own ltn12.filter.chain is done.

Implemented part of DB's suggestion for ftp.
Mimetest.lua generates the test file for base64 instead of loading from disk.

TODO

@@ -4,7 +4,6 @@ new scheme to choose family/protocol of object to create
 change ltn13 to make sure drawbacks are obvious
     - check discussion
 make sure errors not thrown by try() are not caught by protect()
-use wim's filter.chain or something better
 use mike's "don't set to blocking before closing unless needed" patch?
 take a look at DB's smtp patch (add "extra argument" table)
 move wsocket.c:sock_send kludge to buffer.c:sendraw (probably)?
@@ -24,6 +23,7 @@ testar os options!
   - proteger ou atomizar o conjunto (timedout, receive), (timedout, send)
   - inet_ntoa também é uma merda.
 
+*use wim's filter.chain or something better
 *fix PROXY in http.lua
 *use new distribution scheme
 *create the getstats method. 

src/ftp.lua

@@ -125,8 +125,10 @@ function metat.__index:send(sendt)
     if string.find(code, "1..") then self.try(self.tp:check("2..")) end
     -- done with data connection
     self.data:close()
+    -- find out how many bytes were sent
+    local sent = socket.skip(1, self.data:getstats())
     self.data = nil
-    return 1
+    return sent
 end
 
 function metat.__index:receive(recvt)
@@ -186,9 +188,10 @@ local function tput(putt)
     f:login(putt.user, putt.password)
     if putt.type then f:type(putt.type) end
     f:pasv()
-    f:send(putt)
+    local sent = f:send(putt)
     f:quit()
-    return f:close()
+    f:close()
+    return sent
 end
 
 local default = {

src/ltn12.lua

@@ -31,38 +31,38 @@ function filter.cycle(low, ctx, extra)
     end
 end
 
--- chains a bunch of filters together 
--- by Wim Couwenberg
-function filter.chain(...)
-    local current = 1
-    local bottom = 1
-    local top = table.getn(arg)
-    local retry = "" 
+local function chain2(f1, f2)
+    local ff1, ff2 = "", ""
     return function(chunk)
-        if chunk ~= retry then
-            current = bottom
-            retry = chunk and retry
+        local rf1 = chunk and ""
+        local rf2 = ff1 and ""
+        -- if f2 still has pending data, get it and return it
+        if ff2 ~= rf2 then
+            ff2 = f2(rf2)
+            if ff2 ~= "" then return ff2 end
         end
-        repeat
-            if current == bottom then
-                chunk = arg[current](chunk)
-                if chunk == "" or bottom == top then return chunk
-                elseif chunk then current = current + 1
-                else 
-                    bottom = bottom + 1 
-                    current = bottom
-                end
-            else
-                chunk = arg[current](chunk or "")
-                if chunk == "" then
-                    chunk = retry
-                    current = current - 1
-                elseif current == top then return chunk
-                else current = current + 1
+        -- here we know f2 needs more data
+        -- we try to get it from f1
+        ff1 = f1(chunk)
+        while 1 do
+            -- if f1 can't produce data, we need more data from the user
+            if ff1 == "" then return "" end
+            -- otherwise we pass new data to f2 until it produces something
+            -- or f1 runs out of data too
+            ff2 = f2(ff1) 
+            if ff2 ~= "" then return ff2 end
+            ff1 = f1(rf1)
         end
     end
-        until false
 end
+
+-- chains a bunch of filters together 
+function filter.chain(...)
+     local f = arg[1]
+     for i = 2, table.getn(arg) do
+         f = chain2(f, arg[i])
+     end
+     return f
 end
 
 -----------------------------------------------------------------------------

test/mimetest.lua

@@ -8,13 +8,10 @@ local qptest = "qptest.bin"
 local eqptest = "qptest.bin2"
 local dqptest = "qptest.bin3"
 
-local b64test = "lsocket.2.0.dylib"
-local eb64test = "b64test.bin"
-local db64test = "b64test.bin2"
+local b64test = "b64test.bin"
+local eb64test = "b64test.bin2"
+local db64test = "b64test.bin3"
 
--- make sure test file exists
-local f = assert(io.open(b64test, "r"))
-f:close()
 
 -- from Machado de Assis, "A Mão e a Rosa"
 local mao = [[
@@ -86,6 +83,7 @@ local function named(f, name)
     end
 end
 ]]
+
 local function named(f)
     return f
 end
@@ -188,6 +186,19 @@ local function cleanup_qptest()
     os.remove(dqptest)
 end
 
+-- create test file 
+function create_b64test()
+    local f = assert(io.open(b64test, "wb"))
+    local t = {}
+    for j = 1, 100 do
+        for i = 1, 100 do
+            t[i] = math.random(0, 255)
+        end
+        f:write(string.char(unpack(t)))
+    end
+    f:close()
+end
+
 local function encode_b64test()
     local e1 = mime.encode("base64")
     local e2 = mime.encode("base64")
@@ -212,6 +223,7 @@ local function decode_b64test()
 end
 
 local function cleanup_b64test()
+    os.remove(b64test)
     os.remove(eb64test)
     os.remove(db64test)
 end
@@ -221,12 +233,12 @@ local function compare_b64test()
 end
 
 local function identity_test()
-    local chain = ltn12.filter.chain(
-        mime.encode("quoted-printable"),
-        mime.encode("base64"),
-        mime.decode("base64"),
-        mime.decode("quoted-printable")
-    )
+    local chain = named(ltn12.filter.chain(
+        named(mime.encode("quoted-printable"), "1 eq"),
+        named(mime.encode("base64"), "2 eb"),
+        named(mime.decode("base64"), "3 db"),
+        named(mime.decode("quoted-printable"), "4 dq")
+    ), "chain")
     transform(b64test, eb64test, chain)
     compare(b64test, eb64test)
     os.remove(eb64test)
@@ -271,6 +283,7 @@ end
 local t = socket.gettime()
 
 identity_test()
+create_b64test()
 encode_b64test()
 decode_b64test()
 compare_b64test()