luaL_addlstring
luaL_addlstring(B, s, strlen(s));
luaL_addlstring(B, s, l);
luaL_addlstring(&b, s, wild - s); /* push prefix */
LUALIB_API void (luaL_addlstring) (luaL_Buffer *B, const char *s, size_t l);
luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
luaL_addlstring(b, s, e - s);
luaL_addlstring(&b, src, ms.src_end-src);
luaL_addlstring(&b, sep, lsep);