Re: Calling back into Lua: Coroutines, ffi and the C api
- From: Mike Pall <mike-1311@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Tue, 19 Nov 2013 12:55:24 +0100
Nils Nordman wrote:
> A partial call stack can thus end up looking something like this:
>
> C -> C api -> Lua -> ffi call -> C -> C api -> Lua
This is not a valid call stack. You must not use the Lua/C API
from an FFI call.
A simple test is to ask: where has the 'C api' part in your call
stack gotten its lua_State pointer? The FFI deliberately doesn't
provide one -- don't pass a lua_State behind its back.
> C -> C api -> Lua (coroutine.create/resume) -> ffi call -> C -> C api (SEGV)
Ditto.
> 3) In the coroutine case, if the SEGV is to be expected, would the
> situation change if a ffi callback was used instead of using the C api
> for call backs? Or if the C api was used instead of the ffi?
An FFI callback would work. But please read this first:
http://luajit.org/ext_ffi_semantics.html#callback
--Mike
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