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Date: Thu, 1 May 2003 10:07:13 -0500
From: "Jacques A. Vidrine" <nectar@FreeBSD.org>
To: Dag-Erling Smorgrav <des@ofug.org>
Message-ID: <20030501150713.GA34992@madman.celabo.org>
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cc: hackers@freebsd.org
Subject: Re: incorrect enum warning?
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On Thu, May 01, 2003 at 04:51:40PM +0200, Dag-Erling Smorgrav wrote:
> Why does the following code in OpenPAM headers:
> 
> /*
>  * XSSO 5.4
>  */
> enum {
>         PAM_SILENT                      = 0x80000000,
>         PAM_DISALLOW_NULL_AUTHTOK       = 0x1,
>         PAM_ESTABLISH_CRED              = 0x1,
>         PAM_DELETE_CRED                 = 0x2,
>         PAM_REINITIALIZE_CRED           = 0x4,
>         PAM_REFRESH_CRED                = 0x8,
>         PAM_PRELIM_CHECK                = 0x1,
>         PAM_UPDATE_AUTHTOK              = 0x2,
>         PAM_CHANGE_EXPIRED_AUTHTOK      = 0x4
> };
> 
> cause the following warning when compiled with CSTD=c99:
> 
> /usr/src/contrib/openpam/include/security/pam_constants.h:100: warning: ISO C restricts enumerator values to range of `int'
> 
> when 0x80000000 is clearly within the range of 'int' on all platforms
> we support?

Guessing:
C does not specify one's complement or two's complement representation
of integers.  On a one's complement 32-bit platform, 0x80000000 is -0
(negative zero), which cannot be an `int'.

Cheers,
-- 
Jacques Vidrine   . NTT/Verio SME      . FreeBSD UNIX       . Heimdal
nectar@celabo.org . jvidrine@verio.net . nectar@freebsd.org . nectar@kth.se