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From: ekrell@hector.UUCP (Eduardo Krell)
Newsgroups: comp.unix.questions
Subject: Re: Symbolic Links in Sys 5.3.1
Message-ID: <3121@ulysses.homer.nj.att.com>
Date: Mon, 26-Oct-87 22:17:59 EST
Article-I.D.: ulysses.3121
Posted: Mon Oct 26 22:17:59 1987
Date-Received: Thu, 29-Oct-87 05:44:25 EST
References: <3680027@nucsrl.UUCP> <3680028@nucsrl.UUCP>
Sender: daemon@ulysses.homer.nj.att.com
Reply-To: ekrell@hector (Eduardo Krell)
Organization: AT&T Bell Labs, Murray Hill
Lines: 34

In article <3680028@nucsrl.UUCP> naim@nucsrl.UUCP (Naim Abdullah) writes:

>I have deleted two lines of comments and two lines of code in the ifdef
>because I don't want to be sued by AT&T for revealing any of their
>proprietary secrets, but suffice it to say that the vanilla
>Sys5.3.1 kernel appears to have some support for plugging
>in a filesystem containing symbolic links.

The support is really not there. The code you mention is just an attempt
to guess where the support for symbolic links should be in the generic
namei() and the file system specific namei().

>Anybody, know
>how to do that, or whether the kernel needs some more work
>to support symbolic links ?

To start with, you need 3 new system calls: lstat(), readlink() and symlink(),
as per BSD Unix. You will have to change the RFS kernel drivers to allow
for these system calls to "go remote" when appropriate. You'll also have to
decide what to do with a symbolic link which is resolved in a remote
machine and happens to start with a "/" : does it refer to the root on the
remote machine or the root on the machine that initiated the system call?

On the user-level side, you need to add the C library entry points for the
3 new system calls, and change many user level commands to understand symbolic
links (tar, find, file, mv/cp/ln, rm, etc.). Add the -L option to ls and the
-s option to ln (to create symbolic links), fix fsck so that it won't
get rid of all symbolic links thinking they are illegal inode types.

That's about it ...
    
    Eduardo Krell                   AT&T Bell Laboratories, Murray Hill

    {ihnp4,seismo,ucbvax}!ulysses!ekrell