From owner-freebsd-hackers  Mon Oct 29 15:22:49 2001
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Date: Mon, 29 Oct 2001 15:22:45 -0800 (PST)
From: k Macy <kip_macy@yahoo.com>
Subject: Re: problems with recurring SIGTRAP under gdb 
To: Ian Dowse <iedowse@maths.tcd.ie>
Cc: freebsd-hackers@freebsd.org
In-Reply-To: <200110291230.aa64062@salmon.maths.tcd.ie>
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SIGIO is used, but only for AIO and at this point no 
aio_* calls have been made. 

The loop for reading from STDIN may be a problem but I
don't see how - this same loop is used without
problems 
on Linux, OSF, and Solaris (although on Linux if you 
press Ctrl-C in gdb it often won't let you continue):

int 
sim_getc(char *cp)
{
        int r;


        sk_wait_for_fd(0);

        r = read(0, cp, 1);

        if (r <= 0) {
                dbg_printf("pccons_getchar: read
failed: %s\n", error_msg());
                sk_panic("pccons_getchar: failed read
on stdin");
        }

        return r;
}

sk_wait_for_fd is just:
void sk_wait_for_fd(int fd)
{
    int slot;
    sk_Msg *msg;
    if (sk_poll_one_fd(fd)>0) {
        /* fd is already ready */
        return;
    }
    slot = sk_add_poll_fd(fd);
    if(slot < 0)
        return;
    do {
        msg = sk_receive();
        if((msg->type == SK_SIGNAL_MSG) &&
(msg->data.l == HARD_SIG_00010))
            break;

    } while (1);
    sk_remove_poll_fd(slot);
}

beneath this it just uses poll

--- Ian Dowse <iedowse@maths.tcd.ie> wrote:
> In message
>
<20011029023746.94559.qmail@web14001.mail.yahoo.com>,
> k Macy writes:
> >Any idea why when I insert a breakpoint I get a
> >SIGTRAP 
> >and can't continue any further? Is this a bug in
> the 
> 
> I've seen this on applications that use SIGIO on
> stdin. If this is the
> case, a workaround is to disable the SIGIO signal
> while using the
> debugger, e.g:
> 
> 	(gdb) set $oldsigio = signal(23, (void *)1)
> 
> The signal handler can be put back later with:
> 
> 	call signal(23, (void *)$oldsigio)
> 
> Ian


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