[PATCH] lua: fix tarantool -e "os.exit()" hang.

[Vladimir Davydov]

On Wed, Feb 06, 2019 at 02:36:18PM +0300, Serge Petrenko wrote:
> After the patch which made os.exit() execute on_shutdown triggers
> (see commit 6dc4c8d7b5b40d66fe0451ef4d1f4bdf4d2cf60e) we relied
> on on_shutdown triggers to break the ev_loop and exit tarantool.
> Hovewer, there is an auxiliary event loop which is run in
> tarantool_lua_run_script() to reschedule the fiber executing chunks
> of code passed by -e option and executing interactive mode.
> This event loop is started only to execute interactive mode, and
> doesn't exist during execution of -e chunks. Make sure we don't start
> it if os.exit() was already executed in one of the chunks.
> 
> Closes #3966
> ---
> https://github.com/tarantool/tarantool/issues/3966
> https://github.com/tarantool/tarantool/tree/sp/gh-3966-os-exit-hang
> 
>  src/lua/init.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lua/init.c b/src/lua/init.c
> index ca4b47f3a..d18c8af94 100644
> --- a/src/lua/init.c
> +++ b/src/lua/init.c
> @@ -664,7 +664,8 @@ tarantool_lua_run_script(char *path, bool interactive,
>  	 * Run an auxiliary event loop to re-schedule run_script fiber.
>  	 * When this fiber finishes, it will call ev_break to stop the loop.
>  	 */
> -	ev_run(loop(), 0);
> +	if (start_loop)
> +		ev_run(loop(), 0);
>  	/* The fiber running the startup script has ended. */
>  	script_fiber = NULL;
>  }

Please add a test. You might want to take a look at box-py/args.test.py