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X-WM-Posted-At: avacado.atomice.net; Sun, 30 Jun 02 23:23:10 +0100
Message-ID: <01d901c22084$b7552e20$0100a8c0@advent02>
From: "Chris January" <chris AT atomice DOT net>
To: <cygwin-developers AT cygwin DOT com>
References: <00a801c22036$1a7456b0$0100a8c0 AT advent02> <20020630171026 DOT GB32201 AT redhat DOT com>
Subject: Re: changes to fhandler_process.cc from 02/06/2002 should be reverted
Date: Sun, 30 Jun 2002 23:23:09 +0100
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> >I've just seen this ChangeLog entry, Chris:
> >
> >2002-06-02  Christopher Faylor  <cgf AT redhat DOT com>
> >
> > Remove unneeded sigproc.h includes throughout.
> > * fhandler.h (fhandler_proc::fill_filebuf): Take a pinfo argument.
> > * fhandler_proc.cc (fhandler_proc::get_proc_fhandler): Simplify search
> > for given pid.
> > (fhandler_proc::readdir): Assume that pid exists if it shows up in the
> > winpid list.
> > * fhandler_process.cc (fhandler_process::open): Simplify search for
> > given pid.  Call fill_filebuf with pinfo argument.
> > (fhandler_process::fill_filebuf): Pass pinfo here and assume that it
> > exists.
> > * pinfo.h (pinfo::remember): Define differently if sigproc.h is not
> > included.
> >
> >IMHO, these changes need to be reverted. fhandler_base::fill_filebuf is
> >virtual. If you add the pinfo parameter to
fhandler_process::fill_filebuf,
> >then you are defining a new function, not overriding the one in
> >fhandler_base. Hence, /proc semantics whereby the file contents are
> >refreshed on an lseek are broken.
>
> I'll certainly consider changes, but your previous method of searching
> the whole process table for a given pid when there already is a method
> available for directly getting to the pid itself was flawed.  You used
> this technique throughout your proc code and I thought it demonstrated
> an unfamiliarity with the way that the pinfo class was supposed to work,
> so I fixed it.
>
> I will put back the pinfo pointer in the fhandler_process class but I
> don't think that the entire checkin evidenced by the ChangeLog above
> needs to be reverted.
I took a look at your changes and this still won't work. Look at where
fill_filebuf is called in fhandler_virtual::lseek. The p member of
fhandler_process must be valid at this point, but it is not because the code
in fhandler_process::open sets it back to NULL after it has called
fill_filebuf. The reason for calling fill_filebuf in lseek is that this is
how the Linux proc utilities work - they open the file and then call seek
(fd, 0, SEEK_SET) when they want the file contents updated.

Chris