From: Mike Frysinger <vapier@gentoo.org>
To: Jeff Layton <jlayton@redhat.com>
Cc: libc-alpha@sourceware.org, linux-fsdevel@vger.kernel.org,
Michael Kerrisk <mtk.manpages@gmail.com>,
Carlos O'Donell <carlos@redhat.com>,
Yuriy Kolerov <Yuriy.Kolerov@synopsys.com>
Subject: Re: [glibc PATCH] fcntl: put F_OFD_* constants under #ifdef __USE_FILE_OFFSET64
Date: Wed, 17 Aug 2016 18:43:00 -0000 [thread overview]
Message-ID: <20160817184333.GC21655@vapier.lan> (raw)
In-Reply-To: <1471445251-2450-1-git-send-email-jlayton@redhat.com>
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On 17 Aug 2016 10:47, Jeff Layton wrote:
> The Linux kernel expects a flock64 structure whenever you use OFD locks
> with fcntl64. Unfortunately, you can currently build a 32-bit program
> that passes in a struct flock when it calls fcntl64.
>
> Only define the F_OFD_* constants when __USE_FILE_OFFSET64 is also
> defined, so that the build fails in this situation rather than
> producing a broken binary.
this seems to be going against the glibc API/guarantees we've provided
before (or at least tried to promise), and what the fcntl(2) man page
says now. namely, we haven't documented F_GETLK64 or struct flock64,
with the expectation that the user just calls fcntl() with a struct
flock. in fact, the man page even goes so far as to discourage people
from using the *64 variants.
it should be possible using our existing LFS framework to make the OFD
cmds available even to 32-bit apps (where sizeof(off_t) == 32). but
maybe the usage of F_GETLK64/struct flock64/etc... in the real world
has made it hard to put that genie back in the bottle ? we'd have to
version the current fcntl symbol, create a new fcntl symbol that does
32->64 munging, and add a new fcntl64 symbol that we'd transparently
rewrite to when LFS is turned on.
-mike
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next prev parent reply other threads:[~2016-08-17 18:43 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-17 14:47 Jeff Layton
2016-08-17 15:44 ` Joseph Myers
2016-08-17 17:50 ` Jeff Layton
2016-08-17 17:57 ` Joseph Myers
2016-08-17 18:23 ` Jeff Layton
2016-08-17 16:13 ` Mike Frysinger
2016-08-17 17:34 ` Florian Weimer
2016-08-17 17:40 ` Jeff Layton
2016-08-17 18:02 ` Florian Weimer
2016-08-17 18:21 ` Jeff Layton
2016-08-17 18:51 ` Florian Weimer
2016-08-17 19:20 ` Jeff Layton
2016-08-18 8:44 ` Florian Weimer
2016-08-18 8:59 ` Andreas Schwab
2016-08-17 20:52 ` Andreas Schwab
2016-08-18 8:45 ` Florian Weimer
2016-08-17 18:43 ` Mike Frysinger [this message]
2016-08-17 19:15 ` Jeff Layton
2016-08-17 19:59 ` Michael Kerrisk (man-pages)
2016-08-17 20:05 ` Jeff Layton
2016-08-17 20:37 ` Mike Frysinger
2016-08-17 20:58 ` Jeff Layton
2016-08-17 21:35 ` Mike Frysinger
2016-08-17 21:48 ` Jeff Layton
2016-08-18 9:00 ` Florian Weimer
2016-08-23 11:09 ` Cyril Hrubis
2016-08-23 11:36 ` Jeff Layton
2016-08-23 11:43 ` Cyril Hrubis
2016-08-23 21:11 ` Michael Kerrisk (man-pages)
2016-11-14 13:45 ` Cyril Hrubis
2016-11-22 18:41 ` Florian Weimer
2016-08-18 8:57 ` Florian Weimer
2016-08-17 20:03 ` Mike Frysinger
2016-08-17 21:35 ` Cyril Hrubis
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