[sane-devel] [dev] net backend and timing problems? (pretty weird)

[Henning Meier-Geinitz]

Hi,

On Thu, Sep 06, 2001 at 12:34:19PM +0200, mh wrote:
> when I try to scan over saned (localhost) using the net/plustek backend, the
> frontend crashes with a bt like this:
> 
> Program received signal SIGPIPE, Broken pipe.
> 0x403f7004 in write () from /lib/libc.so.6
> (gdb) bt
> #0  0x403f7004 in write () from /lib/libc.so.6
> #1  0x404a6408 in __DTOR_END__ () from /usr/local/lib/sane/libsane-net.so.1
> #2  0x404a45ca in flush (w=0x810f164) at sanei_wire.c:345
> #3  0x404a4614 in sanei_w_set_dir () at sanei_wire.c:345
> #4  0x404a468b in sanei_w_call () at sanei_wire.c:345
> ...

Can you provide some more lines of backtrace so we can see what
sane-net is trying to achieve here? What's in line 345? Is this a
modified sanei_wire.c? I'm asking because flush() starts in line  390
in the code I have. Also I don't understand #2 -> #1 -> #0 , because I
don't see where write () would be involved in flush ().

> static SANE_Status
> do_cancel (Net_Scanner * s)
> {
>   sleep(3); /* <--- add this line */
>   s->hw->auth_active = 0;
>   if (s->data >= 0)
>     {
>       close (s->data);
>       s->data = -1;
>     }
>   return SANE_STATUS_CANCELLED;
> }
> 
> then everything seems to work fine. The scanner returns to the start position,
> the whole stuff freezes for 3 seconds, but i don't get a SIGPIPE.

Just a quick guess: Some sort of race between the final sane_cancel
and sane_read which leads to closing the data connection before
sane_read has finished? I don't know if something like that is possible.
Does this also happen if you use saned in debug mode and are there any
errors/warnings from saned or the plustek backend (with
SANE_DEBUG_PLUSTEK=255)?

Bye,
  Henning