Path: utzoo!mnetor!uunet!husc6!necntc!ames!ptsfa!ihnp4!uniq!dfm
From: dfm@uniq.UUCP (Meyer)
Newsgroups: comp.lang.c
Subject: Re: (So-Called) ANSI C
Message-ID: <400@uniq.UUCP>
Date: 23 Dec 87 16:38:23 GMT
References: <4668@pyr.gatech.EDU> <2046@haddock.ISC.COM>
Sender: news@uniq.UUCP
Organization: Uniq Digital Technologies, Batavia, IL
Lines: 26
Summary: string literals are not writable



In article <2046@haddock.ISC.COM> karl@haddock.ISC.COM (Karl Heuer) writes:

> ...
> The only one that springs to my mind is mktemp("fooXXXXXX") (because it's no
> longer safe to assume that string literals are writable).

I can't remember where it was (maybe some obscure version within AT&T,
like MERT or one of their early 3B series), but there was an implementation
where string constants were put in read-only (text??) memory, and changing
them produced a memory fault or protection violation or some other core-
producing signal.

Even worse, there was one implementation (I believe it was IS/1, a UNIX
emulator that ran on VMS, from Interactive Systems), where the first
page of data was write-protected (this had the beneficial side effect of
catching references through a NULL pointer) but the rest was not, so most
string literals wer writable but some weren't.

Since then, I have never assumed that I could write into a literal.

Dennis F. Meyer				...ihnp4!uniq!dfm
Uniq Digital Technologies
28 S. Water St.
Batavia, IL  60510			312/879-1566