🚀 go-pugleaf

In a previous article, kanze@lts.sel.alcatel.de (James Kanze US/ESC 60/3/141 #40763) said:
>In article <DG010o.LFK@research.att.com> ark@research.att.com (Andrew
>Koenig) writes:
>|> For example, I know a number of people who were involved in
>|> developing the Unix system commands.  When they started using
>|> machines that checked for attempts to read location 0, programs
>|> that had been apparently working for years started crashing.
>|> There had been stray pointer errors in lots of these programs
>|> that turned out in practice to be harmless.
>
>I remember when this happened at one of my customers (10 or 12 years
>ago).  Basically, our earlier versions of Unix had put a '\0' at
>address 0, so it looked like an empty string.  One of the programmers
>who was caught out actually claimed that this was standard Unix, and
>we didn't have the right to change it.

I've heard this argument too: "Too much BSD code assumes that the entire first
page of memory is 0, so you can't make your Unix system map out the first page
to catch null memory accesses without breaking large parts of your OS".
Sounds like a good reason for fixing the marginal hacks in BSD, to me.

(The reason for making the whole first page 0?  If you accessed a member of a
structure through a null pointer, you wanted it to be zero as well!)
-- 
Paul Tomblin, Contract Programmer.
I don't speak for Kodak, they don't speak for me.
(Email that is not work related should go to: ptomblin@canoe.com)
"You are in a twisty maze of Motif Widget resources, all inconsistent."