Question

typedef int (*lua_Writer) (lua_State *L,
 const void* p,
 size_t sz,
 void* ud);

The writer function used by lua_dump. Every time it produces another piece of chunk, lua_dump calls the writer, passing along the buffer to be written (p), its size (sz), and the data parameter supplied to lua_dump.

The writer returns an error code: 0 means no errors; any other value means an error and stops lua_dump from calling the writer again.