From: Rich Felker <dalias@aerifal.cx>
To: Andrey Melnikov <temnota.am@gmail.com>
Cc: musl@lists.openwall.com
Subject: [musl] Re: move __BYTE_ORDER definition to alltypes.h
Date: Tue, 26 Jan 2021 12:23:31 -0500 [thread overview]
Message-ID: <20210126172330.GB23432@brightrain.aerifal.cx> (raw)
In-Reply-To: <CA+PODjoUKSfu1Z+b2PukoVOKOCrfzhLAkDa2VOjvNQYnd9Hc1A@mail.gmail.com>
On Tue, Jan 26, 2021 at 02:55:09PM +0300, Andrey Melnikov wrote:
> Hi.
>
> Your commit 97d35a552ec5b6ddf7923dd2f9a8eb973526acea leads to
> miscompile programs which rely on one of defines __LITTLE_ENDIAN or
> __BIG_ENDIAN.
> Now, both unconditionally defined when included stdarg.h and programs
> which define __(BIG|LITTE)_ENDIAN itself - miscompiled. linux kernel
> for example - it internally uses #if defined __BIG_ENDIAN and defines
> it only for BIGENDAIN arches.
>
> Any ideas?
The conditionally-defined macros that on some archs tell you the
endianness are __BIG_ENDIAN__ and __LITTLE_ENDIAN__ (note the final
__) or other arch-specific macros. __BIG_ENDIAN and __LITTLE_ENDIAN
(without the final __) have always been the possible values for
__BYTE_ORDER from endian.h. In any case, all of these are in the
reserved namespace and should not be defined by applications or
inspected in any way other than a manner documented by the
implementation.
How did this come up with the Linux kernel? AFAIK it uses -nostdinc
and should not see the libc headers at all. But if that #ifdef is
present in Linux it's probably a bug since it's contrary to all
historical use of __BIG_ENDIAN...
Rich
next parent reply other threads:[~2021-01-26 17:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+PODjoUKSfu1Z+b2PukoVOKOCrfzhLAkDa2VOjvNQYnd9Hc1A@mail.gmail.com>
2021-01-26 17:23 ` Rich Felker [this message]
2021-01-26 21:29 ` Andrey Melnikov
2021-01-26 21:40 ` Rich Felker
2021-01-27 8:12 ` Andrey Melnikov
2021-01-27 15:45 ` Rich Felker
2021-01-28 12:45 ` Andrey Melnikov
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