Re: Xavate crash and coxpcall missing 'arg' variable

[Javier Guerra <javier@...>]

On 16 may 2005, at 1:49 PM, Romulo Bahiense wrote:

> Hi,
>
> 	In my attempt to get Xavante running, I came across an unusual 
> problem.
>
> 	After configuring all paths and dependencies, when I << require 
> 't_xavante_start.lua' >>, Lua throws an error:

the files starting with 't_' are templates.  they're supposed to be 
modified by the install procedure.  to be honest, i haven't checked how 
that works; i install them by hand and execute the final 
'xavante_start.lua' as:

lua xavante_start.lua


> (...)coxpcall.lua:19: bad argument #1 to `unpack' (table expected, got 
> nil)

xpcall() doesn't work well across coroutines; therefore coxpcall() is 
used to bridge them. unfortunately, most errors are lost, and _EVERY_ 
case turns up as an error in coxpcall().  usually there's a bit of 
stack info with the real error source.  could you include the whole 
message?

> 	Naturally, I opened the file to look what could had caused the error. 
> I found that there are no 'arg' variable (local or function parameter) 
> and IMHO it shouldn't be in globals.

'arg' is an array automatically filled with any extra parameters beyond 
those indicated in a function definition; it's not a global var.


> 	If I comment that piece of code ( << unpack(arg) >> ), everything 
> goes fine, except that the Xavante crashes if I stress it. I don't 
> really know if Xavante does crash because of that call or because 
> something else.

definitely you shouldn't remove that line.

> 	I'm using the latest downloadable (non-cvs) files for LuaSocket, 
> Xavante, Copas, coxpcall, lfs and compat-5.1. Lua version is 5.0.2. 
> I'm also using Windows XP pro sp2.
>
> 	To try to reproduce the crash, just start Xavante, open your browser, 
> and smack down the Refresh button. In not-so-many requests, Lua prompt 
> will end with no error messages - just end.

most probably any error message that might be generated was lost 
because of the change in coxpcall

> 	Please note that the same occurs when I'm using luahttpd. I just had 
> to change some things to get luahttpd 'running': first, the namespace 
> problems like << require "url" >> to << require "socket.url" >>. 
> Second, apparently luahttpd was using an older (or different) of 
> copas. It was attempting to call 'skt_wrap', which didn't exist (ok, I 
> just renamed the reference from skt_wrap to wrap and worked the same 
> way).

luahttpd is very obsolete and deprecated.  all development since 
several months ago is done for Xavante

--
Javier