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From: John Cowan <cowan@ccil.org>
To: Steve Nickolas <usotsuki@buric.co>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] reviving a bit of WWB
Date: Mon, 21 Sep 2020 16:50:14 -0400	[thread overview]
Message-ID: <CAD2gp_T=RjQkrFeaeu-e4b4qvQFa-uZWTgg6mBiOJhF5fJh9qw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2009210151560.11761@sd-119843.dedibox.fr>

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On Mon, Sep 21, 2020 at 1:55 AM Steve Nickolas <usotsuki@buric.co> wrote:


> I've never written anything that uses varargs, so I've never run into
> that.  But I've actually done quite a bit of work with an environment
> where this isn't true: MS-DOS using the large or huge model.  In this
> environment, sizeof(int)=2, and sizeof(void*) is 4. Of course, it's not
> conformant to pass an int variable as an argument where a pointer variable
> is expected.
>

If the compiler was ISO-conformant (which it almost certainly was not),
that would not matter.  0 in int context would be a 2-byte int with all
bits zero, and 0 in pointer context would be a 4-byte null pointer,
probably with all bits zero.

C doesn't require that the address represented by the null pointer (whether
or not it is all-bits-zero) is inaccessible, merely that there is no C
object or function there.  A simple shim of the appropriate size (1, 2, 4,
8 bytes depending on the CPU's alignment rules) will suffice.

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  parent reply	other threads:[~2020-09-21 20:50 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-20 23:00 Norman Wilson
2020-09-20 23:53 ` Clem Cole
2020-09-21  0:00   ` Clem Cole
2020-09-21  2:24     ` John Cowan
2020-09-21  0:09   ` Warner Losh
2020-09-21  1:05     ` Clem Cole
2020-09-21  5:55     ` Steve Nickolas
2020-09-21  5:59       ` Warner Losh
2020-09-21 18:40         ` Paul Winalski
2020-09-21 19:56           ` Dan Cross
2020-09-21 20:50       ` John Cowan [this message]
2020-09-21 21:22         ` Rob Pike
2020-09-21 21:57           ` Clem Cole
2020-09-21 23:56             ` John Cowan
2020-09-22  0:54               ` Richard Salz
2020-09-21 21:39         ` Steve Nickolas
  -- strict thread matches above, loose matches on Subject: below --
2020-09-25 14:19 Doug McIlroy
2020-09-28 17:35 ` Angelo Papenhoff
2020-09-20 22:51 Norman Wilson
2020-09-19  1:51 Doug McIlroy
2020-09-20 18:42 ` arnold
2020-09-20 19:28   ` Will Senn
2020-09-20 20:12     ` Steve Nickolas
2020-09-20 20:26       ` Doug McIlroy
2020-09-20 20:57         ` Doug McIlroy
2020-09-20 22:13           ` Clem Cole
2020-09-21 20:43             ` Steffen Nurpmeso
2020-09-20 20:58         ` Steve Nickolas
2020-09-20 21:33           ` Brantley Coile
2020-10-07  5:43             ` scj
2020-09-20 21:35           ` John Cowan
2021-02-02 23:08             ` Greg A. Woods
2021-02-02 23:47               ` Larry McVoy
2021-02-03  0:11                 ` Dave Horsfall
2021-02-03  0:19                   ` Larry McVoy
2021-02-03  2:04                     ` Richard Salz
2021-02-03  3:32                       ` Dave Horsfall
2021-02-03  4:32                         ` M Douglas McIlroy
2021-02-03 11:27                           ` Peter Jeremy via TUHS
2021-02-03 20:09                             ` Dave Horsfall
2021-02-03 20:13                               ` Niklas Karlsson
2021-02-03 23:46                               ` Tom Lyon
2021-02-03 22:19                           ` Dave Horsfall
2021-02-03 22:55                             ` M Douglas McIlroy
2020-09-20 22:15           ` Clem Cole
2020-09-20 22:47             ` John Cowan
2020-09-21 20:48               ` Steffen Nurpmeso
2020-09-21 20:46           ` Steffen Nurpmeso
2020-09-24  2:25       ` Dave Horsfall
2020-09-24  2:33         ` Clem Cole
2020-09-27  5:54           ` Dave Horsfall
2020-09-24 17:19         ` Paul Winalski
2020-09-24 18:17           ` John Cowan
2020-10-07  5:47   ` scj
2020-10-07  9:20     ` arnold
2020-10-08  0:27     ` Dave Horsfall
2020-10-08  3:08       ` John Cowan

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