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Re: fstatat + AT_NO_AUTOMOUNT
From: |
Paul Eggert |
Subject: |
Re: fstatat + AT_NO_AUTOMOUNT |
Date: |
Mon, 7 Mar 2022 09:11:33 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 |
On 3/7/22 07:02, Pádraig Brady wrote:
When looking into https://bugs.gnu.org/54286
which discussed statx + AT_NO_AUTOMOUNT,
I was wondering about the fstatat changes in
https://github.com/coreutils/coreutils/commit/571f63f50
and whether some of those should also specify AT_NO_AUTOMOUNT?
I'm a bit lost, as I see no mention of fstatat in that commit.
I was not aware of AT_NO_AUTOMOUNT until now, and am surprised about it.
POSIX says that stat(f,s) is supposed to be equivalent to
fstatat(AT_FDCWD,f,s,0). But if I understand things correctly, this
isn't true on GNU/Linux: you must pass AT_NO_AUTOMOUNT instead of 0. I
assume that this departure from POSIX was intentional, but even so it's
pretty confusing. Could you explain why AT_NO_AUTOMOUNT wasn't made the
default for fstatat?
I suppose we first need to audit all of Gnulib's uses of fstatat and
statx to see whether they need AT_NO_AUTOMOUNT added. Once we're done
with that we can turn to Coreutils.
For example, what about the calls to fstatat in gnulib/lib/openat.h? Are
statat and lstatat intended as convenient aliases for fstatat, or as
directory-fd extensions to stat and lstat? If the former, they should be
left alone; if the latter, they need AT_NO_AUTOMOUNT. Or perhaps it
would be better to eliminate them and replace them with calls to
fstatat, since we'll need to decide on a call-by-call basis anyway.
Another example: what about the fstatat call in gnulib/lib/fchmodat.c? I
suppose we should not add AT_NO_AUTOMOUNT there, under the theory that
GNU/Linux faccessat does not do the equivalent of AT_NO_AUTOMOUNT. Is
that right?
- fstatat + AT_NO_AUTOMOUNT, Pádraig Brady, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT,
Paul Eggert <=
- Re: fstatat + AT_NO_AUTOMOUNT, Pádraig Brady, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Paul Eggert, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Pádraig Brady, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Paul Eggert, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Pádraig Brady, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Paul Eggert, 2022/03/07
- Re: fstatat + AT_NO_AUTOMOUNT, Paul Eggert, 2022/03/09
- Re: fstatat + AT_NO_AUTOMOUNT, Andreas Schwab, 2022/03/10
- [PATCH] fix descriptions for AT_NO_AUTOMOUNT, Pádraig Brady, 2022/03/10
- Re: [PATCH] fix descriptions for AT_NO_AUTOMOUNT, Paul Eggert, 2022/03/10