Path: utzoo!news-server.csri.toronto.edu!rutgers!usc!wuarchive!waikato.ac.nz!ldo
From: ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Oh THIS is interesting (opening resources)
Message-ID: <1991Mar12.172552.3105@waikato.ac.nz>
Date: 12 Mar 91 04:25:52 GMT
References: <1991Mar11.233539.21549@potomac.ads.com>
Organization: University of Waikato, Hamilton, New Zealand
Lines: 19

The way I understand it, _OpenRF returns an i/o refnum for the resource
fork, the same way _Open returns one for the data fork. You can
use this resource fork refnum with all the regular file i/o
calls (_Read, _Write, _SetEOF etc), and when you've finished with
it, you close it with _Close.

If you open the data fork at the same time, you'll get a different
refnum, which you can use with the same calls, as though it were a
completely separate file. No conflict.

As for differences between resource forks of supposedly identical
files, it could just be because part of the first 256 bytes of the resource
fork is "reserved for system use" (see Inside Mac pgs I-128 to I-129).
Maybe something gets written here during the copying process--who knows?

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 26" S, 175^ 19' 7" E, GMT+13:00