Date: 01 Jun 2001 08:32:23 +0800 From: Jiangyi Liu <gzjyliu@public.guangzhou.gd.cn> To: diman <diman@asd-g.com> Cc: freebsd-hackers@FreeBSD.org Subject: Re: FIX needed. Was: Weird PT_DETACH Message-ID: <878zjdnip4.fsf@fatcow.home> In-Reply-To: <Pine.BSF.4.21.0105311233490.266-300000@portal.none.ua> References: <Pine.BSF.4.21.0105311233490.266-300000@portal.none.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi,
diman <diman@asd-g.com> writes:
>
> Another problem(?) Jiangui found considers PT_DETACH ptrace(2)
> call. While i'm attaching to a running process via PT_ATTACH,
> PT_DETACH works well as expected.
> If i instead use PT_TRACE_ME -> execve -> PT_DETACH,
> child always got killed by SIGTRAP.
> I'm not sure it's a bug - needs play a bit more with gdb... ..
>
Maybe it's not a bug. It's a feature. :-) Notice execve() in
sys/kern/kern_exec.c:
/*
* If tracing the process, trap to debugger so breakpoints
* can be set before the program executes.
*/
STOPEVENT(p, S_EXEC, 0);
if (p->p_flag & P_TRACED)
psignal(p, SIGTRAP);
> Attached is a simple program i used for tests.
> Note that Jiangyi Liu reported same effects on 4.3-S.
>
> Sorry Jiangyi Liu, I wrong understood you yesterday -
> needs more more more sleeping :~)
>
Never mind. Maybe enough sleeping and morning jogging do good to
hacking. But it's almost impossible. :-)
Cheers,
Jiangyi Liu
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?878zjdnip4.fsf>