cdata conversion failure with ffi.string()

[Markus Korber <korbse@...>]

Hi there,

I'm trying to use the FFI with the code given here to serialize a C 
struct: 
https://stackoverflow.com/questions/12344095/how-do-i-convert-a-cdata-structure-into-a-lua-string/12347111#12347111 


However, using Lua 5.1 I always get the following error message: lua: 
./temp.lua:22: unable to convert cdata to string
Any idea what can be wrong with ffi.string()?

br,
Markus