Messages in this thread | | | Date | Mon, 17 Jan 2000 23:46:23 +0100 | From | almesber@lrc ... | Subject | Re: Why wrapping PIDs is evil [was 32bit] |
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Stefan Monnier wrote: > allow a potential killer to hold on to a process (preventing its > entry from being reused)
... with dire implications if you fail to kill after grabbing or are evil-minded.
What about a much simpler solution: - make PIDs very long (e.g. 32 bits) - only expose 15 bits, as we do now - make sure PIDs are unique within the lower 15 bits (otherwise, programs using 15 bit PIDs would see duplicate processes) - start counting PIDs at a value >= 32768 - include the full PID somewhere in /proc/<PID>/stat - change the kill system call such that it looks for process->pid == pid if pid >> 15, or !((process->pid ^ pid) & 0x7fff) PID & 0x7fff otherwise - extend programs like killall and fuser to use the long PID from stat - use only those programs for killing (extending the normal ps and kill would of course be trivial, too)
If you put the kernel side of all this into 2.3/2.4, I'll make the necessary extension to killall and fuser. Do we have a deal ? ;-)
- Werner
-- _________________________________________________________________________ / Werner Almesberger, ICA, EPFL, CH werner.almesberger@ica.epfl.ch / /_IN_N_032__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/
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