diff --git a/ltests/ltests.c b/ltests/ltests.c
diff --git a/ltests/ltests.h b/ltests/ltests.h
@@ -0,0 +1,129 @@
+/*
+** $Id: ltests.h,v 2.50 2016/07/19 17:13:00 roberto Exp $
+** Internal Header for Debugging of the Lua Implementation
+** See Copyright Notice in lua.h
+*/
+
+#ifndef ltests_h
+#define ltests_h
+
+
+#include <stdlib.h>
+
+/* test Lua with no compatibility code */
+#undef LUA_COMPAT_MATHLIB
+#undef LUA_COMPAT_IPAIRS
+#undef LUA_COMPAT_BITLIB
+#undef LUA_COMPAT_APIINTCASTS
+#undef LUA_COMPAT_FLOATSTRING
+#undef LUA_COMPAT_UNPACK
+#undef LUA_COMPAT_LOADERS
+#undef LUA_COMPAT_LOG10
+#undef LUA_COMPAT_LOADSTRING
+#undef LUA_COMPAT_MAXN
+#undef LUA_COMPAT_MODULE
+
+
+#define LUA_DEBUG
+
+
+/* turn on assertions */
+#undef NDEBUG
+#include <assert.h>
+#define lua_assert(c)           assert(c)
+
+
+/* to avoid warnings, and to make sure value is really unused */
+#define UNUSED(x)       (x=0, (void)(x))
+
+
+/* test for sizes in 'l_sprintf' (make sure whole buffer is available) */
+#undef l_sprintf
+#if !defined(LUA_USE_C89)
+#define l_sprintf(s,sz,f,i)	(memset(s,0xAB,sz), snprintf(s,sz,f,i))
+#else
+#define l_sprintf(s,sz,f,i)	(memset(s,0xAB,sz), sprintf(s,f,i))
+#endif
+
+
+/* memory-allocator control variables */
+typedef struct Memcontrol {
+  unsigned long numblocks;
+  unsigned long total;
+  unsigned long maxmem;
+  unsigned long memlimit;
+  unsigned long objcount[LUA_NUMTAGS];
+} Memcontrol;
+
+LUA_API Memcontrol l_memcontrol;
+
+
+/*
+** generic variable for debug tricks
+*/
+extern void *l_Trick;
+
+
+
+/*
+** Function to traverse and check all memory used by Lua
+*/
+int lua_checkmemory (lua_State *L);
+
+
+/* test for lock/unlock */
+
+struct L_EXTRA { int lock; int *plock; };
+#undef LUA_EXTRASPACE
+#define LUA_EXTRASPACE	sizeof(struct L_EXTRA)
+#define getlock(l)	cast(struct L_EXTRA*, lua_getextraspace(l))
+#define luai_userstateopen(l)  \
+	(getlock(l)->lock = 0, getlock(l)->plock = &(getlock(l)->lock))
+#define luai_userstateclose(l)  \
+  lua_assert(getlock(l)->lock == 1 && getlock(l)->plock == &(getlock(l)->lock))
+#define luai_userstatethread(l,l1) \
+  lua_assert(getlock(l1)->plock == getlock(l)->plock)
+#define luai_userstatefree(l,l1) \
+  lua_assert(getlock(l)->plock == getlock(l1)->plock)
+#define lua_lock(l)     lua_assert((*getlock(l)->plock)++ == 0)
+#define lua_unlock(l)   lua_assert(--(*getlock(l)->plock) == 0)
+
+
+
+LUA_API int luaB_opentests (lua_State *L);
+
+LUA_API void *debug_realloc (void *ud, void *block,
+                             size_t osize, size_t nsize);
+
+#if defined(lua_c)
+#define luaL_newstate()		lua_newstate(debug_realloc, &l_memcontrol)
+#define luaL_openlibs(L)  \
+  { (luaL_openlibs)(L); \
+     luaL_requiref(L, "T", luaB_opentests, 1); \
+     lua_pop(L, 1); }
+#endif
+
+
+
+/* change some sizes to give some bugs a chance */
+
+#undef LUAL_BUFFERSIZE
+#define LUAL_BUFFERSIZE		23
+#define MINSTRTABSIZE		2
+#define MAXINDEXRK		1
+
+
+/* make stack-overflow tests run faster */
+#undef LUAI_MAXSTACK
+#define LUAI_MAXSTACK   50000
+
+
+#undef LUAI_USER_ALIGNMENT_T
+#define LUAI_USER_ALIGNMENT_T   union { char b[sizeof(void*) * 8]; }
+
+
+#define STRCACHE_N	23
+#define STRCACHE_M	5
+
+#endif
+
diff --git a/luamem_wrapapi.lua b/luamem_wrapapi.lua
@@ -0,0 +1,105 @@
+local _G = require "_G"
+local getmetatable = _G.getmetatable
+local pairs = _G.pairs
+local select = _G.select
+local setmetatable = _G.setmetatable
+local tonumber = _G.tonumber
+local type = _G.type
+
+---[[
+local newmem = memory.create
+--[=[]]
+local create = memory.create
+local resize = memory.resize
+local function newmem(str)
+	local m = create()
+	resize(m, #str, str)
+	return m
+end
+--]=]
+
+local function tomemval(v)
+	if type(v) == "string" then
+		return newmem(v)
+	end
+	return v
+end
+
+local function tomemnotnum(v)
+	if type(v) == "string" and tonumber(v) == nil then
+		return newmem(v)
+	end
+	return v
+end
+
+local function tomemstrorfunc(chunk)
+	local t = type(chunk)
+	if t == "string" then
+		return memory.create(chunk)
+	elseif t == "function" then
+		return function (...)
+			return tomemval(chunk(...))
+		end
+	end
+	return chunk
+end
+
+local tomemvararg = setmetatable({}, {__index = function () return tomemval end})
+local tomemnotnumva = setmetatable({false}, {__index = function () return tomemnotnum end})
+
+local wraps = {
+	[_G] = {
+		print = tomemvararg,
+		load = {tomemstrorfunc},
+	},
+	[io] = {
+		write = tomemvararg,
+	},
+	[getmetatable(io.stdout).__index] = {
+		write = tomemvararg,
+	},
+	[string] = {
+		sub = {tomemval},
+		reverse = {tomemval},
+		lower = {tomemval},
+		upper = {tomemval},
+		rep = {tomemval, false, tomemval},
+		byte = {tomemval},
+		find = {tomemval},
+		match = {tomemval},
+		gmatch = {tomemval},
+		gsub = {tomemval, false, tomemstrorfunc},
+		format = tomemnotnumva,
+		pack = tomemnotnumva,
+		unpack = {nil, tomemval},
+	},
+	[table] = {
+		concat = {tomemval, tomemval},
+	},
+	[utf8] = {
+		len = {tomemval},
+		codepoint = {tomemval},
+		offset = {tomemval},
+		codes = {tomemval},
+	},
+}
+
+local function wrapargs(i, args, ...)
+	if select("#", ...) > 0 then
+		local value = ...
+		local convert = args[i]
+		if convert then
+			value = convert(value)
+		end
+		return value, wrapargs(i+1, args, select(2, ...))
+	end
+end
+
+for module, funcs in pairs(wraps) do
+	for name, args in pairs(funcs) do
+		local backup = module[name]
+		module[name] = function (...)
+			return backup(wrapargs(1, args, ...))
+		end
+	end
+end
diff --git a/tpack.lua b/tpack.lua
@@ -204,6 +204,9 @@ do
 
   checkerror("contains zeros", pack, "z", "alo\0");
 
+  checkerror("too short", unpack, "z", "alo");
+  checkerror("too short", unpack, "z", "");
+
   for i = 2, NB do
     local s1 = pack("s" .. i, s)
     assert(unpack("s" .. i, s1) == s and #s1 == #s + i)