509124b626
It is currently allowed to fchownat(2), fchmodat(2), fchflagsat(2), utimensat(2), fstatat(2), and linkat(2). For linkat(2), PRIV_VFS_FHOPEN privilege is required to exercise the flag. It allows to link any open file. Requested by: trasz Tested by: pho, trasz Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D29111
323 lines
7.9 KiB
Groff
323 lines
7.9 KiB
Groff
.\" $NetBSD: utimes.2,v 1.13 1999/03/22 19:45:11 garbled Exp $
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.\"
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.\" Copyright (c) 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\" Copyright (c) 2012, Jilles Tjoelker
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)utimes.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd March 30, 2021
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.Dt UTIMENSAT 2
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.Os
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.Sh NAME
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.Nm futimens ,
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.Nm utimensat
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.Nd set file access and modification times
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/stat.h
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.Ft int
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.Fn futimens "int fd" "const struct timespec times[2]"
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.Ft int
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.Fo utimensat
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.Fa "int fd"
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.Fa "const char *path"
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.Fa "const struct timespec times[2]"
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.Fa "int flag"
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.Fc
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.Sh DESCRIPTION
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The access and modification times of the file named by
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.Fa path
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or referenced by
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.Fa fd
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are changed as specified by the argument
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.Fa times .
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The inode-change-time of the file is set to the current time.
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.Pp
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If
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.Fa path
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specifies a relative path,
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it is relative to the current working directory if
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.Fa fd
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is
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.Dv AT_FDCWD
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and otherwise relative to the directory associated with the file descriptor
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.Fa fd .
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.Pp
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The
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.Va tv_nsec
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field of a
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.Vt timespec
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structure
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can be set to the special value
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.Dv UTIME_NOW
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to set the current time, or to
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.Dv UTIME_OMIT
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to leave the time unchanged.
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In either case, the
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.Va tv_sec
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field is ignored.
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.Pp
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If
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.Fa times
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is
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.No non- Ns Dv NULL ,
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it is assumed to point to an array of two timespec structures.
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The access time is set to the value of the first element, and the
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modification time is set to the value of the second element.
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For file systems that support file birth (creation) times (such as
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.Dv UFS2 ) ,
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the birth time will be set to the value of the second element
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if the second element is older than the currently set birth time.
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To set both a birth time and a modification time,
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two calls are required; the first to set the birth time
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and the second to set the (presumably newer) modification time.
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Ideally a new system call will be added that allows the setting
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of all three times at once.
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If
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.Fa times
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is
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.Dv NULL ,
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this is equivalent to passing
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a pointer to an array of two timespec structures
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with both
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.Va tv_nsec
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fields set to
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.Dv UTIME_NOW .
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.Pp
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If both
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.Va tv_nsec
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fields are
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.Dv UTIME_OMIT ,
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the timestamps remain unchanged and
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no permissions are needed for the file itself,
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although search permissions may be required for the path prefix.
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The call may or may not succeed if the named file does not exist.
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.Pp
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If both
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.Va tv_nsec
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fields are
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.Dv UTIME_NOW ,
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the caller must be the owner of the file, have permission to
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write the file, or be the super-user.
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.Pp
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For all other values of the timestamps,
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the caller must be the owner of the file or be the super-user.
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.Pp
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The values for the
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.Fa flag
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argument of the
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.Fn utimensat
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system call
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are constructed by a bitwise-inclusive OR of flags from the following list,
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defined in
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.In fcntl.h :
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.Bl -tag -width indent
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.It Dv AT_SYMLINK_NOFOLLOW
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If
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.Fa path
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names a symbolic link, the symbolic link's times are changed.
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By default,
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.Fn utimensat
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changes the times of the file referenced by the symbolic link.
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.It Dv AT_RESOLVE_BENEATH
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Only walk paths below the directory specified by the
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.Ar fd
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descriptor.
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See the description of the
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.Dv O_RESOLVE_BENEATH
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flag in the
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.Xr open 2
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manual page.
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.It Dv AT_EMPTY_PATH
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If the
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.Fa path
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argument is an empty string, operate on the file or directory
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referenced by the descriptor
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.Fa fd .
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If
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.Fa fd
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is equal to
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.Dv AT_FDCWD ,
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operate on the current working directory.
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.El
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.Sh RETURN VALUES
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.Rv -std
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.Sh COMPATIBILITY
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If the running kernel does not support this system call,
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a wrapper emulates it using
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.Xr fstatat 2 ,
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.Xr futimesat 2
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and
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.Xr lutimes 2 .
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As a result, timestamps will be rounded down to the nearest microsecond,
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.Dv UTIME_OMIT
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is not atomic and
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.Dv AT_SYMLINK_NOFOLLOW
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is not available with a path relative to a file descriptor.
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.Sh ERRORS
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These system calls will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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The
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.Fa times
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argument is
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.Dv NULL ,
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or both
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.Va tv_nsec
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values are
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.Dv UTIME_NOW ,
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and the effective user ID of the process does not
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match the owner of the file, and is not the super-user, and write
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access is denied.
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.It Bq Er EFAULT
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The
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.Fa times
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argument
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points outside the process's allocated address space.
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.It Bq Er EINVAL
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The
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.Va tv_nsec
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component of at least one of the values specified by the
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.Fa times
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argument has a value less than 0 or greater than 999999999 and is not equal to
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.Dv UTIME_NOW
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or
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.Dv UTIME_OMIT .
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.It Bq Er EIO
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An I/O error occurred while reading or writing the affected inode.
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.It Bq Er EINTEGRITY
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Corrupted data was detected while reading from the file system.
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.It Bq Er EPERM
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The
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.Fa times
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argument is not
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.Dv NULL
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nor are both
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.Va tv_nsec
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values
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.Dv UTIME_NOW ,
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nor are both
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.Va tv_nsec
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values
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.Dv UTIME_OMIT
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and the calling process's effective user ID
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does not match the owner of the file and is not the super-user.
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.It Bq Er EPERM
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The named file has its immutable or append-only flag set, see the
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.Xr chflags 2
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manual page for more information.
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.It Bq Er EROFS
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The file system containing the file is mounted read-only.
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.El
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.Pp
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The
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.Fn futimens
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument
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does not refer to a valid descriptor.
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.El
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.Pp
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The
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.Fn utimensat
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er EBADF
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The
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.Fa path
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argument does not specify an absolute path and the
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.Fa fd
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argument is neither
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.Dv AT_FDCWD
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nor a valid file descriptor.
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.It Bq Er EFAULT
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The
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.Fa path
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argument
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points outside the process's allocated address space.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Dv NAME_MAX
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characters, or an entire path name exceeded
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.Dv PATH_MAX
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characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENOTDIR
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The
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.Fa path
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argument is not an absolute path and
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.Fa fd
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is neither
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.Dv AT_FDCWD
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nor a file descriptor associated with a directory.
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.It Bq Er ENOTCAPABLE
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.Fa path
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is an absolute path,
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or contained a ".." component leading to a
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directory outside of the directory hierarchy specified by
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.Fa fd ,
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and the process is in capability mode or the
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.Dv AT_RESOLVE_BENEATH
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flag was specified.
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.El
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.Sh SEE ALSO
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.Xr chflags 2 ,
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.Xr stat 2 ,
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.Xr symlink 2 ,
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.Xr utimes 2 ,
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.Xr utime 3 ,
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.Xr symlink 7
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.Sh STANDARDS
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The
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.Fn futimens
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and
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.Fn utimensat
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system calls are expected to conform to
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.St -p1003.1-2008 .
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.Sh HISTORY
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The
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.Fn futimens
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and
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.Fn utimensat
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system calls appeared in
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.Fx 10.3 .
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