Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: print return code bug...
Message-ID: <7996@jpl-devvax.JPL.NASA.GOV>
Date: 6 May 90 02:36:27 GMT
References: <1990May4.202029.9341@eci386.uucp>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 39

In article <1990May4.202029.9341@eci386.uucp> clewis@eci386 (Chris Lewis) writes:
: Unless I've missed something, this is supposed to fill up your
: file system and then stop, but it ain't stopping:
: 
: > open(handle, ">/usr5/test");
: > printf $!;
: > $v = "1111111111111111111111111111111111111111111111111111111111111111111";
: > $v = "$v$v$v$v$v$v$v$v$v$v$v";
: > #	Speedups
: > $v = substr($v, 0, 511);
: > $! = "";
: > while(1) {
: >     (printf handle ($v)) || die "BOOM! $! $@";
: > }
: 
: Be careful about running this ;-) if you want to test it, you might want
: to try something different - the point is, printf doesn't appear to be
: returning 0 on a write error (as the manual appears to imply it should -
: it does say print is supposed to and then defines printf in terms of
: print)..

Hmm, apparently fwrite() isn't checking the error status if it has to do a
flush.  Nothing much I can do about that.

You can check it yourself though if you say

	select(handle); $| = 1;

This causes an explicit fflush(), which perl checks the error status of.

On the other hand, perhaps I can force errno to a 0 before the fwrite()
and then see if it gets set.  Hang on, let me try that...

Ok, that seems to work ok.  I just hope nobody's fwrite() sets errno just
for the fun of it.

Someday I'm just gonna bypass fwrite() altogether...

Larry