== More on _chroot()_'s history, and my blind spot about System III

In a comment on [[my entry on _chroot()_'s history ChrootHistory]],
Greg A. Woods noted that System III is the first Unix where _chroot()_
actually prevents your process from just doing _chdir("/..")_ to
escape the new root directory. System III predates 4.x BSD, so I
was more or less wrong in [[my entry on this ChrootHistoryII]].
Only in the BSD line was 4.1c the starting point for this bit of
_chroot()_ security. System III source code is even available
online [[here http://minnie.tuhs.org/cgi-bin/utree.pl]], so I
could have checked and seen this myself if I'd thought of it.

I didn't, though, and that's because I have a blind spot about
System III. For a long time Unix was split into two sides, which
I'll call the university side and the commercial side. BSD and all
of its descendents come from the university side; System III and
then System V came from the commercial side. The university side
dominated both in universities themselves and in Sun and DEC
workstations that more or less derived from that environment,
while the commercial side mostly wound up in high end big iron
servers.

(SGI was an odd case; it was System V derived but had a bunch of
BSD stuff added. This caused a certain amount of heartburn in people
who dealt with it.)

Although I've used System V machines, in cultural terms I come from
the university side of Unix; it's what I have the most exposure to,
what I'm most familiar with, and as a result it's what I reflexively
think of as 'real Unix'. In other words, it's a tribal affiliation.
With a few exceptions I tend to just assume that BSD did something
first and best, and that [[System V had a lot of hacks SystemVIPCStory]].
So when I was looking at the history of _chroot()_, I didn't pay a
lot of attention to System III; I didn't really look to see the
state of _chroot()_ in it, and I didn't actually look at its release
date (which is surprisingly early).

(It looks like System III and information about it probably wasn't
publicly available early enough to influence BSD's _chroot()_ stuff,
but it's at least possible I'm wrong here and that hearing about
_chroot()_ security in System III helped push BSD to implement it.)

This is, of course, kind of a mistake. System III and later System
V had their own innovations, _chroot()_ security among them, and I
shouldn't dismiss their contributions to Unix so reflexively and
tribally (even if AT&T too often had [[terrible ideas there
ATTUnixUnbundlingDamage]]).