Re: unprotected error in call to Lua API (13)

[Philipp Janda <siffiejoe@...>]

Am 08.10.2015 um 09:12 schröbte Dirk Laurie:
> 2015-10-08 0:36 GMT+02:00 Elie Michel <elie.michel@exppad.com>:
> > I have at the beginning something like this:
> >
> >      if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0)) {
> >          cout << "Error: " << lua_tostring(L, -1) << endl;
> >      }
> > ...
> > if (lua_pcall(L, 1, 0, 0)) {
> >         cout << "Error: " << lua_tostring(L, -1) << endl;
> >    }
>
> The error code for luaL_loadfile can only be 2,4 or 6 and for lua_pcall
> 2,4 or 6 so 13 does not come from here.
>
> Find other places in your code with "Error:"

If I interpret the subject (unprotected error in call to Lua API) 
correctly, the error happens *outside* of every `pcall`. So it's the 
`panic` function in `lauxlib.c` (`lib_aux.c` in case of LuaJIT) which is 
printing the error message, not the OP. The good news is that you can 
put a debugger break point on `panic` (or `exit`) and see in the 
backtrace where the error is thrown. "13" is a strange error message 
though, so I suspect that the Lua stack gets messed up somehow in the 
loop. Maybe a Lua(JIT) library with API checks enabled 
(`-DLUA_USE_APICHECK`) can shed some light ...

Anyway, unprotected errors smell bad, so I recommend putting (almost) 
all interaction with the Lua API into a `lua_CFunction` that is called 
via `lua_cpcall`. See the source code of the Lua interpreter (`lua.c`) 
for an example.

HTH,
Philipp