Subject: Re: negative user-ids and interoperability.
To: Giles Lean <email@example.com>
From: Simon Burge <firstname.lastname@example.org>
Date: 04/26/1999 23:19:16
Giles Lean wrote:
> Then I think I recall that some of the archive formats (cpio?) have
> restrictions on user ids. The HP-UX manual page claims that user ids
> greater than 60K are restored as the current user id because of this.
> The UNIX 98 cpio(1) manual page doesn't mention user ids.
> While I've never seen a document describing the cpio archive format
> just about everything in cpio is a 16 bit quantity, so I assume that
> "60K" here is 2^16-1. Of course, cpio is pretty much dead and
> deprecated in UNIX 98.
In "portable archive format" (ASCII data), from Ultrix's <cpio.h>:
and these are stored in octal. So nobody (-2) on an Ultrix cpio archive
is represented as "177776" - (2^16)-2. "cpio -ivt < foo" on a NetBSD
system shows userid of 65534 - interoperability at it's finest :-)
Same result for a "native" cpio achive on a machine with the same
endianess as the generating machine...
> What a mess. Maybe "nobody" in /etc/passwd isn't such a bad idea.
I'm starting to think so...