UTIMENSAT(2) FreeBSD System Calls Manual UTIMENSAT(2)
NAME
futimens, utimensat - set file access and modification times
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/stat.h>
int
futimens(int fd, const struct timespec times[2]);
int
utimensat(int fd, const char *path, const struct timespec times[2],
int flag);
DESCRIPTION
The access and modification times of the file named by path or referenced
by fd are changed as specified by the argument times. The inode-change-
time of the file is set to the current time.
If path specifies a relative path, it is relative to the current working
directory if fd is AT_FDCWD and otherwise relative to the directory
associated with the file descriptor fd.
The tv_nsec field of a timespec structure can be set to the special value
UTIME_NOW to set the current time, or to UTIME_OMIT to leave the time
unchanged. In either case, the tv_sec field is ignored.
If times is non-NULL, it is assumed to point to an array of two timespec
structures. The access time is set to the value of the first element,
and the modification time is set to the value of the second element. For
file systems that support file birth (creation) times (such as UFS2), the
birth time will be set to the value of the second element if the second
element is older than the currently set birth time. To set both a birth
time and a modification time, two calls are required; the first to set
the birth time and the second to set the (presumably newer) modification
time. Ideally a new system call will be added that allows the setting of
all three times at once. If times is NULL, this is equivalent to passing
a pointer to an array of two timespec structures with both tv_nsec fields
set to UTIME_NOW.
If both tv_nsec fields are UTIME_OMIT, the timestamps remain unchanged
and no permissions are needed for the file itself, although search
permissions may be required for the path prefix. The call may or may not
succeed if the named file does not exist.
If both tv_nsec fields are UTIME_NOW, the caller must be the owner of the
file, have permission to write the file, or be the super-user.
For all other values of the timestamps, the caller must be the owner of
the file or be the super-user.
The values for the flag argument of the utimensat() system call are
constructed by a bitwise-inclusive OR of flags from the following list,
defined in <fcntl.h>:
AT_SYMLINK_NOFOLLOW
If path names a symbolic link, the symbolic link's times are
changed. By default, utimensat() changes the times of the file
referenced by the symbolic link.
AT_RESOLVE_BENEATH
Only walk paths below the directory specified by the fd
descriptor. See the description of the O_RESOLVE_BENEATH flag in
the open(2) manual page.
AT_EMPTY_PATH
If the path argument is an empty string, operate on the file or
directory referenced by the descriptor fd. If fd is equal to
AT_FDCWD, operate on the current working directory.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
COMPATIBILITY
If the running kernel does not support this system call, a wrapper
emulates it using fstatat(2), futimesat(2) and lutimes(2). As a result,
timestamps will be rounded down to the nearest microsecond, UTIME_OMIT is
not atomic and AT_SYMLINK_NOFOLLOW is not available with a path relative
to a file descriptor.
ERRORS
These system calls will fail if:
[EACCES] The times argument is NULL, or both tv_nsec values are
UTIME_NOW, and the effective user ID of the process
does not match the owner of the file, and is not the
super-user, and write access is denied.
[EFAULT] The times argument points outside the process's
allocated address space.
[EINVAL] The tv_nsec component of at least one of the values
specified by the times argument has a value less than
0 or greater than 999999999 and is not equal to
UTIME_NOW or UTIME_OMIT.
[EIO] An I/O error occurred while reading or writing the
affected inode.
[EINTEGRITY] Corrupted data was detected while reading from the
file system.
[EPERM] The times argument is not NULL nor are both tv_nsec
values UTIME_NOW, nor are both tv_nsec values
UTIME_OMIT and the calling process's effective user ID
does not match the owner of the file and is not the
super-user.
[EPERM] The named file has its immutable or append-only flag
set, see the chflags(2) manual page for more
information.
[EROFS] The file system containing the file is mounted read-
only.
The futimens() system call will fail if:
[EBADF] The fd argument does not refer to a valid descriptor.
The utimensat() system call will fail if:
[EACCES] Search permission is denied for a component of the
path prefix.
[EBADF] The path argument does not specify an absolute path
and the fd argument is neither AT_FDCWD nor a valid
file descriptor.
[EFAULT] The path argument points outside the process's
allocated address space.
[ELOOP] Too many symbolic links were encountered in
translating the pathname.
[ENAMETOOLONG] A component of a pathname exceeded NAME_MAX
characters, or an entire path name exceeded PATH_MAX
characters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
[ENOTDIR] The path argument is not an absolute path and fd is
neither AT_FDCWD nor a file descriptor associated with
a directory.
[ENOTCAPABLE] path is an absolute path, or contained a ".."
component leading to a directory outside of the
directory hierarchy specified by fd, and the process
is in capability mode or the AT_RESOLVE_BENEATH flag
was specified.
SEE ALSO
chflags(2), stat(2), symlink(2), utimes(2), utime(3), symlink(7)
STANDARDS
The futimens() and utimensat() system calls are expected to conform to
IEEE Std 1003.1-2008 ("POSIX.1").
HISTORY
The futimens() and utimensat() system calls appeared in FreeBSD 10.3.
FreeBSD 13.1-RELEASE-p6 March 30, 2021 FreeBSD 13.1-RELEASE-p6
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