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From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: pwd in perl
Message-ID: <1990Aug10.220614.12305@iwarp.intel.com>
Date: 10 Aug 90 22:06:14 GMT
References: <1990Aug10.205437.21409@uvaarpa.Virginia.EDU>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 29
In-Reply-To: marc@mit.edu

In article <1990Aug10.205437.21409@uvaarpa.Virginia.EDU>, marc@mit writes:
| |> Another thing that I don't think has been mentioned, is that you might
| |> be in a directory whose parent directory you have no access to.  In
| |> this case reading ..'s files until you find . will not work.  This is
| |> why pwd must be setuid root, so that it can do the appropriate checks.
| 
| If you have no access to the parent, how did you get to where you are
| now?  I think it's a safe assumption that you can read all the
| directories up to the root.  My system makes this assumption; /bin/pwd
| is not setuid root.  I think a lot of programs probably depend on
| getwd() working.  Here, if getwd ()doesn't work, the shell won't even
| do the right thing.

You can have 'x' access and no 'r' access.  On your system, /bin/pwd
would fail in this case, and so would any call to getwd() or the Perl
routine that's been published (or anything from user-level non-setuid
code).  I think that's why /bin/pwd is setuid on some machines.
(Interesting...  it's not setuid on Sunos4.1 either)

I agree with Larry, though.  chop($pwd = `pwd`) is portable and fast,
and there are more important features for Larry to add (I know, I've
been writing about them for a week now :-).

print "Just another Perl hacker,"
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
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