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Groups > comp.os.linux.development.system > #107

Re: per process llseek offset

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On May 1, 10:41 pm, "dr.oktopus" <blindwi...@freeonline.zzn.com>
wrote:
> Hi,
> as you know offset in the file structure is shared amongst father and
> child
> processes. How can I get a per-process specific offset so that a child
> lseek is
> not influenced by the same operation done by the father process? A
> possibility
> is build a list of pid and associate offset and, for every read or
> write operation, look for the
> pid of the process and get appropriate offset. This is the method used
> in Linux Device
> Drivers book (the example is tty-local specific, but could be adapted
> for processes).
> I would like to know if other methods exists.
> Thanks,
>              willy

It's not clear what the "I" is that you're talking about. Are you
talking about what a device driver can do? It can trivially keep a
table of PIDs and offsets. Are you talking about what a process can do
to keep its own offset? Or hwat?

Personally, I would strongly urge you to keep the offsets shared.
That's what processes will expect, and I can't imagine why you would
want to behave differently from the way everything else behaves.

DS

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Thread

per process llseek offset "dr.oktopus" <blindwilly@freeonline.zzn.com> - 2011-05-01 22:41 -0700
  Re: per process llseek offset David Schwartz <davids@webmaster.com> - 2011-05-02 03:50 -0700
    Re: per process llseek offset "dr.oktopus" <blindwilly@freeonline.zzn.com> - 2011-05-02 15:39 -0700
      Re: per process llseek offset Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-02 20:25 -0600
  Re: per process llseek offset Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-05-02 13:07 +0100

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