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From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.questions
Subject: Re: Killing the correct process
Message-ID: <5713@star.cs.vu.nl>
Date: 1 Mar 90 03:06:47 GMT
References: <22332@adm.BRL.MIL> <5312@star.cs.vu.nl> <1212@root44.co.uk> <5382@buengc.BU.EDU> <5615@star.cs.vu.nl> <5405@buengc.BU.EDU> <5636@star.cs.vu.nl> <5410@buengc.BU.EDU> <5650@star.cs.vu.nl> <5414@buengc.BU.EDU>
Sender: news@cs.vu.nl
Reply-To: maart@cs.vu.nl (Maarten Litmaath)
Followup-To: comp.unix.questions
Organization: VU Informatika, Amsterdam, the Netherlands
Lines: 33

In article <5414@buengc.BU.EDU>,
	bph@buengc.BU.EDU (Blair P. Houghton) writes:
)...
)	fp = popen("/bin/ps axl","r");
)	while ( fgets(line,sizeof(line),fp) != (char *)NULL )
)	    if ( uid == parse_for_uid(line) )
)		kill( parse_for_pid(line), SIGKILL );
)	pclose(fp);
)
)SIG_IGN that!

Between the `ps' and the kill() the user might have created new processes.
Race conditions, babe.

)...
)>I was talking of events with much higher probability.
)
)Wot?  You can assign a PID to your own process?  I'd like
)to see that...

See above.  Talking about assigning your own pid: a friend of mine (Peter
Valkenburg, valke@psy.vu.nl) once wrote a program called `snatch_pid';
you fed it the pid you wanted to grab, then waited an hour or so (ca. 30,000
fork()s on a VAX).  The use: if some game initializes its pseudo random
generator with `srand(getpid())'...

)				--Blair
)				  "Blair -v"

				  "Maarten -SEGV 666 :667 +1 /vmunix"
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