linux-kernel - Re: [parch 2/4] vfs: utimensat(): be consistent with utime() for immutable and append-only files

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Date:	Wed, 04 Jun 2008 06:29:55 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	mtk.manpages@...glemail.com
CC:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	hch@....de, miklos@...redi.hu, viro@...iv.linux.org.uk,
	jamie@...reable.org, drepper@...hat.com,
	linux-fsdevel@...r.kernel.org, subrata@...ux.vnet.ibm.com
Subject: Re: [parch 2/4] vfs: utimensat(): be consistent with utime() for immutable
 and append-only files

> This patch fixes utimensat() to make its behavior consistent
> with that of utime()/utimes() when dealing with files marked
> immutable and append-only.
> 
> The current utimensat() implementation also returns EPERM if
> 'times' is non-NULL and the tv_nsec fields are both UTIME_NOW.
> For consistency, the
> 
> (times != NULL && times[0].tv_nsec == UTIME_NOW &&
>                   times[1].tv_nsec == UTIME_NOW)
> 
> case should be treated like the traditional utimes() case where
> 'times' is NULL.  That is, the call should succeed for a file
> marked append-only and should give the error EACCES if the file
> is marked as immutable.
> 
> The simple way to do this is to set 'times' to NULL
> if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW).
> 
> This is also the natural approach, since POSIX.1 semantics consider the
> times == {{x, UTIME_NOW}, {y, UTIME_NOW}}
> to be exactly equivalent to the case for
> times == NULL.
> 
> (Thanks to Miklos for pointing this out.)
> 
> Patch 3 in this series relies on the simplification provided
> by this patch.
> 
> CC: Miklos Szeredi <miklos@...redi.hu>
> CC: Al Viro <viro@...iv.linux.org.uk>
> CC: Ulrich Drepper <drepper@...hat.com>
> Signed-off-by: Michael Kerrisk <mtk.manpages@...il.com>

Acked-by: Miklos Szeredi <mszeredi@...e.cz>
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