luaZ_bufflen
size_t n = luaZ_bufflen(ls->buff);
#define buff2d(b,e) luaO_str2d(luaZ_buffer(b), luaZ_bufflen(b) - 1, e)
luaZ_bufflen(ls->buff) - 2*(2 + sep));
luaZ_bufflen(ls->buff) - 2);
luaZ_bufflen(ls->buff));
if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {
b->buffer[luaZ_bufflen(b)++] = cast(char, c);