futimens(2) System Calls futimens(2)NAME
futimens, utimensat - set file access and modification times
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 futimens() and utimensat() functions set the access and modifica‐
tion times of a file to the values of the times argument. The futi‐
mens() function changes the times of the file associated with the file
descriptor fd. The utimensat() function changes the times of the file
pointed to by the path argument, relative to the directory associated
with the file descriptor fd. Both functions allow time specifications
accurate to the nanosecond.
The times argument is an array of two timespec structures. The first
array member represents the date and time of last access, and the sec‐
ond member represents the date and time of last modification. The times
in the timespec structure are measured in seconds and nanoseconds since
the Epoch. The file's relevant timestamp is set to the greatest value
supported by the file system that is not greater than the specified
time.
If the tv_nsec field of a timespec structure has the special value
UTIME_NOW, the file's relevant timestamp is 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 rele‐
vant timestamp is not changed. In either case, the tv_sec field is
ignored.
If the times argument is a null pointer, both the access and modifica‐
tion timestamps are set to the greatest value supported by the file
system that is not greater than the current time. If utimensat() is
passed a relative path in the path argument, the file to be used is
relative to the directory associated with the file descriptor fd
instead of the current working directory.
If utimensat() is passed the special value AT_FDCWD in the fd parame‐
ter, the current working directory is used.
Only a process with the effective user ID equal to the user ID of the
file, or with write access to the file, or with appropriate privileges
may use futimens() or utimensat() with a null pointer as the times
argument or with both tv_nsec fields set to the special value
UTIME_NOW. Only a process with the effective user ID equal to the user
ID of the file or with appropriate privileges may use futimens() or
utimensat() with a non-null times argument that does not have both
tv_nsec fields set to UTIME_NOW and does not have both tv_nsec fields
set to UTIME_OMIT. If both tv_nsec fields are set to UTIME_OMIT, no
ownership or permissions check is performed for the file, but other
error conditions are still detected (including EACCES errors related to
the path prefix).
Values for the flag argument of utimensat() are constructed by a bit‐
wise-inclusive OR of flags from the following list, defined in
<fcntl.h>:
AT_SYMLINK_NOFOLLOW
If path names a symbolic link, then the access and modification
times of the symbolic link are changed.
Upon completion, futimens() and utimensat() mark the last file status
change timestamp for update.
RETURN VALUES
Upon successful completion, these functions return 0. Otherwise, these
functions return -1 and set errno to indicate the error. If -1 is
returned, the file times are not affected.
ERRORS
The futimens() and utimensat() functions will fail if:
EACCES The times argument is a null pointer, 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 write access is denied.
EINVAL Either of the times argument structures specified a tv_nsec
value that was neither UTIME_NOW nor UTIME_OMIT, and was a
value less than zero or greater than or equal to 1000 mil‐
lion.
A new file timestamp would be a value whose tv_sec component
is not a value supported by the file system.
EPERM The times argument is not a null pointer, does not have both
tv_nsec fields set to UTIME_NOW, does not have both tv_nsec
fields set to UTIME_OMIT, the calling process' effective user
ID has write access to the file but does not match the owner
of the file, and the calling process does not have appropri‐
ate privileges.
EROFS The file system containing the file is read-only.
The futimens() function will fail if:
EBADF The fd argument is not a valid file descriptor.
The utimensat() function will fail if:
EACCES The permissions of the directory underlying fd do not
permit directory searches.
EBADF The path argument does not specify an absolute path and
the fd argument is neither AT_FDCWD nor a valid file
descriptor open for reading.
ENOTDIR The path argument is not an absolute path and fd is
neither AT_FDCWD nor a file descriptor associated with
a directory.
EACCES Search permission is denied by a component of the path
prefix.
ELOOP Too many symbolic links were encountered during resolu‐
tion of the path argument.
ENAMETOOLONG The length of the path argument exceeds {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.
ENOENT A component of path does not name an existing file or
path is an empty string.
ENOTDIR A component of the path prefix is not a directory, or
the path argument contains at least one character that
is not a slash (/) and ends with one or more trailing
slash characters and the last pathname component names
an existing file that is neither a directory nor a sym‐
bolic link to a directory.
The utimensat() function will fail if:
ENAMETOOLONG Path name resolution of a symbolic link produced an
intermediate result with a length that exceeds
{PATH_MAX}.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Async-Signal-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOstat(2), utime(2), utimes(2), attributes(5), fsattr(5)SunOS 5.10 1 Sep 2009 futimens(2)
