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Date: Wed, 9 Aug 2000 08:54:58 -0700 (PDT)
Message-Id: <200008091554.IAA53597@vashon.polstra.com>
To: hackers@freebsd.org
Cc: archie@whistle.com
Subject: Re: CVS question
In-Reply-To: <200008071906.MAA12811@bubba.whistle.com>
References: <200008071906.MAA12811@bubba.whistle.com>
Organization: Polstra & Co., Seattle, WA
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In article <200008071906.MAA12811@bubba.whistle.com>,
Archie Cobbs  <archie@whistle.com> wrote:
> Consider this source file:
> 
>   http://www.freebsd.org/cgi/cvsweb.cgi/src/usr.sbin/xntpd/lib/Attic/ranny.c
> 
> Question: what version should this command checkout?
> 
>   $ cvs co -D 'January 18, 1999 0:00' freebsd/src/usr.sbin/xntpd/lib/ranny.c
> 
> Perhaps version 1.1.1.2 would be correct, but instead you get 1.1.

CVS is really screwy in this area.  I remember I had to add some
special cases to CVSup long ago to try to mimic CVS's behavior in
odd cases.

> It seems CVS is being inconsistent:
>
> - If you had done a 'head' checkout on that date you would have
> gotten 1.1.1.2

That makes sense, because on that date the file had not yet left the
vendor branch, and its default branch attribute still pointed to the
vendor branch.

> - If you later do a 'head' checkout, and specify that date, you get 1.1

CVS has a heuristic that does the wrong thing for this particular
file.  The code is around line 3252 of src/contrib/cvs/src/rcs.c in
the function RCS_getdate():

        if (! STREQ (cur_rev, "1.1"))
            return (xstrdup (cur_rev));
           
        /* This is 1.1;  if the date of 1.1 is not the same as that for the
           1.1.1.1 version, then return 1.1.  This happens when the first
           version of a file is created by a regular cvs add and commit,
           and there is a subsequent cvs import of the same file.  */
        p = findnode (rcs->versions, "1.1.1.1");
        if (p)
        {
            vers = (RCSVers *) p->data;
            if (RCS_datecmp (vers->date, date) != 0)
                return xstrdup ("1.1");
        }

It compares the dates on the theory that an import will set
identical dates in revisions 1.1 and 1.1.1.1.  But in the file you
mentioned, they are off by 1 second.  So CVS doesn't recognize it as
an import.

    revision 1.1
    date: 1993/12/21 18:36:22;  author: wollman;  state: Exp;

    revision 1.1.1.1
    date: 1993/12/21 18:36:23;  author: wollman;  state: Exp;  lines: +0 -0

Probably the import straddled the seconds boundary.  I hope current
versions of CVS force the dates to be the same on an import.  I
haven't checked to see whether that's the case or not.

John
-- 
  John Polstra                                               jdp@polstra.com
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa



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