From owner-freebsd-hackers  Wed May 30 23:58: 4 2001
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To: diman@asd-g.com (diman)
Subject: Re: Weird PT_DETACH
Cc: freebsd-hackers@FreeBSD.org
References: <006a01c0e911$96e68720$a701160a@fatcow>
	<Pine.BSF.4.21.0105301420150.201-100000@portal.none.ua>
From: Jiangyi Liu <gzjyliu@public.guangzhou.gd.cn>
Date: 31 May 2001 14:57:11 +0800
In-Reply-To: <Pine.BSF.4.21.0105301420150.201-100000@portal.none.ua>
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Hi,

I tried to use (caddr_t)1 in PT_DETACH, but the code just
failed. I'm confused. It just seems the execve is stopped. Maybe I'd read
through the kernel source code to figure out where the problem is.

Jiangyi

diman@asd-g.com (diman) writes:

> 	Hope your program not named "./test"  ??
> 	I changed it to /bin/sh and it works just fine.
> 	It was hard to debug due to my own proggie bug :)
> 	bb.
> 
> 
> #include <unistd.h>
> #include <sys/types.h>
> #include <sys/ptrace.h>
> 
> int main()
> {
>      pid_t pid;
>      
>      if(!(pid=fork())) {
>          /* child */
>          ptrace(PT_TRACE_ME, 0, 0, 0);
>          puts("child speaking");
>          execve("./test", NULL, NULL);		<---------- ??
>      } else {
>          wait(0);
>          ptrace(PT_DETACH, pid, (caddr_t)1, 0); <---------- also
>          exit(0);
>      }
> }
> 
> 
> 
> 
> 
> On Wed, 30 May 2001, Jiangyi Liu wrote:
> 
> > 
> > > 
> > > If i understand ptrace(2) manual page correctly,
> > > you should use 
> > > ptrace(PT_DETACH,pid,(caddr_t)1,0)
> > > instead of 
> > > ptrace(PT_DETACH,pid,0,0) .
> > > 
> > 
> > If you read my first post again, you will know that indeed I've tried to use (caddr_t)1 but failed too.
> > 
> > > BTW you code is *very hard to debug* on my 4.1.1 :)
> > > What your uname -a tells you?
> > 
> > Why? My box is 4.3-STABLE.
> > 
> > Jiangyi
> > 
> 
> 
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