Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!imagen!qubix!wjvax!brett
From: brett@wjvax.UUCP (Brett Galloway)
Newsgroups: comp.lang.c
Subject: Re: exit(-1)
Message-ID: <1179@wjvax.UUCP>
Date: 7 Jan 88 02:36:36 GMT
References: <502@cresswell.quintus.UUCP> <6935@brl-smoke.ARPA>
Reply-To: brett@wjvax.UUCP (Brett Galloway)
Organization: Watkins-Johnson Co., San Jose, Calif.
Lines: 44

In article <6935@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>In article <502@cresswell.quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
>>Except where you are writing code for a specific system (say you
>>have #if cases for MVS, VMS, and UNIX) it seems like a good idea
>>to pass only 0 or 1 to exit().
>
>VMS C would like for exit(1); to also mean "success", we were told,
>so the current proposed standard requires <stdlib.h> to define macros
>EXIT_FAILURE and EXIT_SUCCESS.  Special dispensation was granted to
>the value 0, which also indicates success (the VMS C implementor
>agreed that he could make that work on his system).  All other values
>of the exit status have implementation-defined meaning; they might
>contain system error codes, errno values, or some other stuff with
>non-portable meaning.

It appears to me that requiring EXIT_FAILURE and EXIT_SUCCESS is a
sop to VMS's non-traditional usage.  Now I grant that it is a nice idea to
define EXIT_FAILURE and EXIT_SUCCESS.  I also grant that other exit values
are implementation-defined.  However, it is hard to conceive an implementation
which has multiple exit-success values.  In this context, 0 is by far the
most intuitive choice for EXIT_SUCCESS.

Instead of accommodating VMS's stupid choice of exit values, why not require
an ANSI-conforming VMS C compiler to swap 0 and 1 in the exit() in its C
library?  That way, even if VMS wants to see 1 for success, it will, with
C programs able to return the natural value of 0 for success.  I seem to
recall that VMS already defines macros for error return values.  It could
swap those (make 0 success).  This way, currently-compiled VMS C binaries
would continue to run, and newly-compiled C binaries would also work (they
would get the swapped exit() *and *the new EXIT_FAILURE and EXIT_SUCCESS
macros at the same time.  The only time that there would be a problem would
be a re-link without a re-compile.  Frankly, anybody that would not
re-compile across a transition to an ANSI-conformant compiler deserves what
they get.

This solves the problem for everybody, while leaving conformant the vast body of
programs which use the natural exit(0) => success and exit(!0) => !success.
It puts the burden of conformance upon VMS instead of upon the rest of the
world.  This is apt, since VMS caused the problem in the first place.

-- 
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Brett D. Galloway
{ac6,calma,cerebus,isi,isieng,pyramid,tymix}!wjvax!brett