From mboxrd@z Thu Jan  1 00:00:00 1970
Message-Id: <0C884056-DAC1-484D-880A-30012762C49C@ar.aichi-u.ac.jp>
From: Kenji Arisawa <arisawa@ar.aichi-u.ac.jp>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
In-Reply-To: <a24a8384-832a-4c08-9840-0197284f673e@b16g2000yqb.googlegroups.com>
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Date: Mon,  9 Mar 2009 20:11:28 +0900
References: <a24a8384-832a-4c08-9840-0197284f673e@b16g2000yqb.googlegroups.com>
Subject: Re: [9fans] ping suicide: sys: trap: divide error  pc=0x00003953c
Topicbox-Message-UUID: b671f8c0-ead4-11e9-9d60-3106f5b1d025

Hello,

ip/ping -r -f www.google.com
io% ip/ping -r -f www.google.com
sending 32 64 byte messages 0 ms apart to icmp!www.google.com!1
ping 34691: suicide: sys: trap: divide error pc=3D0x00003953
0: rtt 9797 =B5s, avg rtt 9797 =B5s, ttl =3D 245
io% ps
...
arisawa       34679    0:00   0:00      128K Pread    tcp17010
arisawa       34691    0:00   0:00      140K Broken   ping
arisawa       34695    0:00   0:00      140K Pread    ping
arisawa       34696    0:00   0:00      192K Pread    ps
io% acid 34691
/proc/34691/text:386 plan 9 executable

/sys/lib/acid/port
/sys/lib/acid/386
acid: lstk()
nrand(n=3D0x0)+0x18 /sys/src/libc/port/nrand.c:13
	slop=3D0xa39fb2cf
sender(msglen=3D0x40,n=3D0x20,interval=3D0x0,fd=3D0x6)+0x151 =
/sys/src/cmd/ip/=20
ping.c:268
	seq=3D0xef0c4ef8
	buf=3D0x0
	icmp=3D0xdffeed0e
	me=3D0x0
	mev4=3D0x501a8c0
	i=3D0x1
	r=3D0x22b78
main(argv=3D0xdfffefa0,argc=3D0x1)+0x212 /sys/src/cmd/ip/ping.c:571
	interval=3D0x0
	msglen=3D0x40
	nmsg=3D0x20
	_argc=3D0x66
	_args=3D0xdfffefb8
	ds=3D0x11534
	fd=3D0x6
_main+0x31 /sys/src/libc/386/main9.s:16
acid: =04
echo kill > /proc/34691/ctl
io% cat /sys/src/libc/port/nrand.c
#include	<u.h>
#include	<libc.h>

#define	MASK	0x7fffffffL

int
nrand(int n)
{
	long slop, v;

	if(n < 0)
		return n;
	slop =3D MASK % n;
	do
		v =3D lrand();
	while(v <=3D slop);
	return v % n;
}


Think that where and why nrand(0) is executed and fix the problem.

Kenji Arisawa


On 2009/03/09, at 18:38, ROuNIN wrote:

> Hello all,
> I would like to learn how to fix this in the ping C code, I am new to
> plan9 and C
>
> ip/ping -r -f www.google.com
> sending 32 64 bytes messages 0 ms apart  to icmp!www.google.com!1
> ping 238: suicide: sys: trap: divide error  pc=3D0x00003953
> term% 0: rrt 38841 us, avg rtt 38841 us, ttl =3D 128
>
> ROuNIN
>