Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mgm.mit.edu!wolfgang
From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Newsgroups: comp.unix.wizards
Subject: Re: Aliasing text and data segments of a process
Message-ID: <2624@bloom-beacon.MIT.EDU>
Date: 29 Jan 88 00:04:01 GMT
References: <11476@brl-adm.ARPA> <207@sdti.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Organization: Freelance Software Consultant, Cambridge, Ma.
Lines: 15

In article <207@sdti.UUCP> mjy@sdti.UUCP (0000-Michael J. Young) writes:
>Actually, setting breakpoints is no problem even with the other three types.
>That's what the ptrace(2) system call is for.

If you have a shared-text type of executable, you can't guarentee
ptrace-ability. If someone else is executing the same text, the system
is forced to deny you write-permission with the error 'text busy'.
(Otherwise the other process would also get hit with the breakpoints.)
The other process can still be corrupted however, if it is started
*after* you insert the breakpoints. Now it gets amusing, since you
can't *remove* the breakpoints once the other process is started.
--
Wolfgang Rupprecht	ARPA:  wolfgang@mgm.mit.edu (IP 18.82.0.114)
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