diff --git a/.travis.yml b/.travis.yml
index d15e941..a2f8b17 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,6 +17,7 @@ before_install:
   - bash .travis/setup_lua.sh
   - sudo luarocks install lunitx
   - sudo pip install cpp-coveralls
+  - sudo luarocks install dkjson
 
 install:
   - sudo luarocks make rockspecs/lcurl-scm-0.rockspec CFLAGS="-O2 -fPIC -ftest-coverage -fprofile-arcs" LIBFLAG="-shared --coverage"
diff --git a/src/lceasy.c b/src/lceasy.c
index d47552c..af6bcfe 100644
--- a/src/lceasy.c
+++ b/src/lceasy.c
@@ -696,15 +696,38 @@ static size_t lcurl_read_callback(lua_State *L,
 
   n = lcurl_util_push_cb(L, rd);
   lua_pushinteger(L, ret);
-  if(lua_pcall(L, n, LUA_MULTRET, 0)) return CURL_READFUNC_ABORT;
-
-  if(lua_isnoneornil(L, top + 1)){
-    if(lua_gettop(L) <= (top + 1))return 0;
+  if(lua_pcall(L, n, LUA_MULTRET, 0)){
+    assert(lua_gettop(L) >= top);
+    lua_pushlightuserdata(L, (void*)LCURL_ERROR_TAG);
+    lua_insert(L, top+1);
     return CURL_READFUNC_ABORT;
   }
-  data = lua_tolstring(L, -1, &data_size);
-  if(!data) return CURL_READFUNC_ABORT;
 
+  if(lua_gettop(L) == top){
+    return CURL_READFUNC_ABORT;
+  }
+
+  assert(lua_gettop(L) >= top);
+
+  if(lua_type(L, top + 1) != LUA_TSTRING){
+    if(lua_isnil(L, top + 1)){
+      if(lua_gettop(L) == (top+1)) lua_settop(L, top);
+    }
+    else{
+      if(lua_type(L, top + 1) == LUA_TNUMBER){
+        size_t ret = lua_tonumber(L, top + 1);
+        if(ret == (size_t)CURL_READFUNC_PAUSE){
+          lua_settop(L, top);
+          return CURL_READFUNC_PAUSE;
+        }
+      }
+      lua_settop(L, top);
+    }
+    return CURL_READFUNC_ABORT;
+  }
+
+  data = lua_tolstring(L, top + 1, &data_size);
+  assert(data);
   if(data_size > ret){
     data_size = ret;
     rbuffer->ref = luaL_ref(L, LCURL_LUA_REGISTRY);
diff --git a/test/test_easy.lua b/test/test_easy.lua
index bc48889..773e297 100644
--- a/test/test_easy.lua
+++ b/test/test_easy.lua
@@ -5,6 +5,7 @@ local skip       = lunit.skip or function() end
 
 local curl       = require "lcurl"
 local scurl      = require "lcurl.safe"
+local json       = require "dkjson"
 local url        = "http://example.com"
 local fname      = "./test.download"
 
@@ -17,7 +18,9 @@ local function gc_collect()
   collectgarbage("collect")
 end
 
-local _ENV = TEST_CASE'write_callback' do
+local ENABLE = true
+
+local _ENV = TEST_CASE'write_callback'    if ENABLE then
 
 local c, f
 
@@ -84,6 +87,9 @@ function test_reset_write_callback()
   assert_equal(c, c:setopt_writefunction(f))
   assert_equal(c, c:setopt_writefunction(f.write, f))
   assert_equal(c, c:setopt_writefunction(print))
+  assert_error(function()c:setopt_writefunction()end)
+  assert_error(function()c:setopt_writefunction(nil)end)
+  assert_error(function()c:setopt_writefunction(nil, f)end)
 end
 
 function test_write_pass_01()
@@ -113,10 +119,9 @@ function test_write_pass_03()
   assert_equal(c, c:perform())
 end
 
-
 end
 
-local _ENV = TEST_CASE'progress_callback' do
+local _ENV = TEST_CASE'progress_callback' if ENABLE then
 
 local c
 
@@ -225,7 +230,224 @@ end
 
 end
 
-local _ENV = TEST_CASE'escape' do
+local _ENV = TEST_CASE'header_callback'   if ENABLE then
+
+local c, f
+local function dummy() end
+
+function teardown()
+  if c then c:close() end
+  f, c = nil
+end
+
+function test_header_abort_01()
+  c = assert(scurl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function(str) return #str - 1 end;
+  })
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_WRITE_ERROR), e)
+end
+
+function test_header_abort_02()
+  c = assert(scurl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function(str) return false end;
+  })
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_WRITE_ERROR), e)
+end
+
+function test_header_abort_03()
+  c = assert(scurl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function(str) return nil, "WRITEERROR" end;
+  })
+
+  local _, e = assert_nil(c:perform())
+  assert_equal("WRITEERROR", e)
+end
+
+function test_header_abort_04()
+  c = assert(scurl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function(str) return nil end;
+  })
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_WRITE_ERROR), e)
+end
+
+function test_reset_header_callback()
+  f = {header = function() end}
+  c = assert(curl.easy{url = url})
+  assert_equal(c, c:setopt_headerfunction(f))
+  assert_equal(c, c:setopt_headerfunction(f.header, f))
+  assert_equal(c, c:setopt_headerfunction(print))
+  assert_error(function()c:setopt_headerfunction()end)
+  assert_error(function()c:setopt_headerfunction(nil)end)
+  assert_error(function()c:setopt_headerfunction(nil, f)end)
+end
+
+function test_header_pass_01()
+  c = assert(curl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function(s) return #s end
+  })
+
+  assert_equal(c, c:perform())
+end
+
+function test_header_pass_02()
+  c = assert(curl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function() return  end
+  })
+
+  assert_equal(c, c:perform())
+end
+
+function test_header_pass_03()
+  c = assert(curl.easy{
+    url = url;
+    writefunction = dummy,
+    headerfunction = function() return true end
+  })
+
+  assert_equal(c, c:perform())
+end
+
+
+end
+
+local _ENV = TEST_CASE'reader_callback'   if ENABLE then
+
+local url = "http://httpbin.org/post"
+
+local c, f, t
+
+local function get_bin_by(str,n)
+  local pos = 1 - n
+  return function()
+    pos = pos + n
+    return (str:sub(pos,pos+n-1))
+  end
+end
+
+local function strem(ch, n, m)
+  return n, get_bin_by( (ch):rep(n), m)
+end
+
+local function json_data()
+  return json.decode(table.concat(t))
+end
+
+function setup()
+  t = {}
+  f = assert(scurl.form())
+  c = assert(scurl.easy{
+    url           = url,
+  })
+  assert_equal(c, c:setopt_writefunction(table.insert, t))
+end
+
+function teardown()
+  if f then f:free() end
+  if c then c:close() end
+  t, f, c = nil
+end
+
+function test()
+  assert_equal(f, f:add_stream('SSSSS', strem('X', 128, 13)))
+  assert_equal(c, c:setopt_httppost(f))
+  assert_equal(c, c:perform())
+  assert_equal(200, c:getinfo_response_code())
+  local data = assert_table(json_data())
+  assert_table(data.form)
+  assert_equal(('X'):rep(128), data.form.SSSSS)
+end
+
+function test_abort_01()
+  assert_equal(f, f:add_stream('SSSSS', 128, function() end))
+  assert_equal(c, c:setopt_httppost(f))
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_ABORTED_BY_CALLBACK), e)
+end
+
+function test_abort_02()
+  assert_equal(f, f:add_stream('SSSSS', 128, function() return nil, "READERROR" end))
+  assert_equal(c, c:setopt_httppost(f))
+
+  local _, e = assert_nil(c:perform())
+  assert_equal("READERROR", e)
+end
+
+function test_abort_03()
+  assert_equal(f, f:add_stream('SSSSS', 128, function() return 1 end))
+  assert_equal(c, c:setopt_httppost(f))
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_ABORTED_BY_CALLBACK), e)
+end
+
+function test_abort_04()
+  assert_equal(f, f:add_stream('SSSSS', 128, function() return true end))
+  assert_equal(c, c:setopt_httppost(f))
+
+  local _, e = assert_nil(c:perform())
+  assert_equal(curl.error(curl.ERROR_EASY, curl.E_ABORTED_BY_CALLBACK), e)
+end
+
+function test_abort_04()
+  assert_equal(f, f:add_stream('SSSSS', 128, function() error("READERROR") end))
+  assert_equal(c, c:setopt_httppost(f))
+
+  assert_error_match("READERROR", function() c:perform() end)
+end
+
+function test_pause()
+  local counter = 0
+  assert_equal(f, f:add_stream('SSSSS', 128, function() 
+    if counter == 0 then
+      counter = counter + 1
+      return curl.READFUNC_PAUSE
+    end
+    if counter == 1 then
+      counter = counter + 1
+      return ('X'):rep(128)
+    end
+    return ''
+  end))
+
+  assert_equal(c, c:setopt_progressfunction(function()
+    if counter == 1 then
+      c:pause(curl.PAUSE_CONT)
+    end
+  end))
+
+  assert_equal(c, c:setopt_noprogress(false))
+
+  assert_equal(c, c:setopt_httppost(f))
+
+  assert_equal(c, c:perform())
+  assert_equal(200, c:getinfo_response_code())
+  local data = assert_table(json_data())
+  assert_table(data.form)
+  assert_equal(('X'):rep(128), data.form.SSSSS)
+end
+
+end
+
+local _ENV = TEST_CASE'escape'            if ENABLE then
 
 local c
 
@@ -244,7 +466,7 @@ end
 
 end
 
-local _ENV = TEST_CASE'setopt_form' do
+local _ENV = TEST_CASE'setopt_form'       if ENABLE then
 
 local c