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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: die() exit status and printing $1,$2... in the debugger
Message-ID: <10993@jpl-devvax.JPL.NASA.GOV>
Date: 10 Jan 91 19:55:54 GMT
References: <3000@yarra-glen.aaii.oz.au> <10980@jpl-devvax.JPL.NASA.GOV> <20541:Jan1017:37:5091@kramden.acf.nyu.edu>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 28

In article <20541:Jan1017:37:5091@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
: In article <10980@jpl-devvax.JPL.NASA.GOV> lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes:
: > It would seem that your compiler or run-time system is hosed.  The
: > statement in fatal() in util.c is
: >     statusvalue >>= 8;		/* is an unsigned short */
: >     exit((int)(errno?errno:(statusvalue?statusvalue:255)));
: > How can that return a 0, I ask you?
: 
: Well, since you ask, it can return 0 on most machines if errno is a
: nonzero multiple of 256, or if errno is 0 and statusvalue is a nonzero
: multiple of 256.

Hmm, yes, but I don't think that's what's going on here.  On any machine
with 16-bit shorts, statusvalue can't be a nonzero multiple of 256 because
of the preceding shift, and I don't know of any machines with errno's greater
than 255.

It's vaguely possible that we have a garbaged errno, but I think it's more
likely that we're seeing an endian problem.  There's an alternate
fatal() function with a similar exit(), but without the cast to (int).
Since statusvalue is a short, it might be going into the wrong half of
the int argument to exit.  I'll replace both exit statements with:

    exit((int)((errno&255)?errno:((statusvalue&255)?statusvalue:255)));

That should fix it, one way or the other.

Larry