linux-kernel - [patch 1/4 v2] vfs: utimensat(): ignore tv_sec if tv_nsec == UTIME_OMIT or UTIME

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Message-ID: <484694CD.5020107@gmail.com>
Date:	Wed, 04 Jun 2008 15:12:45 +0200
From:	Michael Kerrisk <mtk.manpages@...glemail.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	lkml <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@....de>,
	Miklos Szeredi <miklos@...redi.hu>, viro@...iv.linux.org.uk,
	jamie@...reable.org, Ulrich Drepper <drepper@...hat.com>,
	linux-fsdevel@...r.kernel.org,
	Subrata Modak <subrata@...ux.vnet.ibm.com>
Subject: [patch 1/4 v2] vfs: utimensat(): ignore tv_sec if tv_nsec == UTIME_OMIT
 or UTIME_NOW

The POSIX.1 draft spec for utimensat() says that if a times[n].tv_nsec
field is UTIME_OMIT or UTIME_NOW, then the value in the corresponding
tv_sec field is ignored.  See the last sentence of this para, from
the spec:

    If the tv_nsec field of a timespec structure has
    the special value UTIME_NOW, the file's relevant
    timestamp shall be set to the greatest value
    supported by the file system that is not greater than
    the current time. If the tv_nsec field has the
    special value UTIME_OMIT, the file's relevant
    timestamp shall not be changed. In either case,
    the tv_sec field shall be ignored.

However the current Linux implementation requires the tv_sec value to be
zero (or the EINVAL error results). This requirement should be removed.

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>

--- linux-2.6.26-rc4/fs/utimes.c	2008-06-04 13:23:38.000000000 +0200
+++ linux-2.6.26-rc4-utimensat-fix-v4/fs/utimes.c	2008-06-04 13:22:44.000000000 +0200
@@ -169,14 +169,6 @@
 	if (utimes) {
 		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
 			return -EFAULT;
-		if ((tstimes[0].tv_nsec == UTIME_OMIT ||
-		     tstimes[0].tv_nsec == UTIME_NOW) &&
-		    tstimes[0].tv_sec != 0)
-			return -EINVAL;
-		if ((tstimes[1].tv_nsec == UTIME_OMIT ||
-		     tstimes[1].tv_nsec == UTIME_NOW) &&
-		    tstimes[1].tv_sec != 0)
-			return -EINVAL;

 		/* Nothing to do, we must not even check the path.  */
 		if (tstimes[0].tv_nsec == UTIME_OMIT &&


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