faccessat - check user's permissions of a file relative to a directory file descriptor
SYNOPSIS
#define _ATFILE_SOURCE#include <fcntl.h> /* Definition of AT_* constants */#include <unistd.h>int faccessat(int dirfd, const char *pathname, int mode, int flags);
DESCRIPTION
The
faccessat()
system call operates in exactly the same way as
access(2),
except for the differences described in this manual page.
If the pathname given in
pathname
is relative, then it is interpreted relative to the directory
referred to by the file descriptor
dirfd
(rather than relative to the current working directory of
the calling process, as is done by
access(2)
for a relative pathname).
If
pathname
is relative and
dirfd
is the special value
AT_FDCWD,
then
pathname
is interpreted relative to the current working
directory of the calling process (like
access(2)).
If
pathname
is absolute, then
dirfd
is ignored.
flags
is constructed by ORing together zero or more of the following values:
AT_EACCESS
Perform access checks using the effective user and group IDs.
By default,
faccessat()
uses the real IDs (like
access(2)).
AT_SYMLINK_NOFOLLOW
If
pathname
is a symbolic link, do not dereference it:
instead return information about the link itself.
RETURN VALUE
On success, (all requested permissions granted)
faccessat()
returns 0.
On error, -1 is returned and
errno
is set to indicate the error.
ERRORS
The same errors that occur for
access(2)
can also occur for
faccessat().
The following additional errors can occur for
faccessat():
EBADF
dirfd
is not a valid file descriptor.
EINVAL
Invalid flag specified in
flags.
ENOTDIR
pathname
is relative and
dirfd
is a file descriptor referring to a file other than a directory.
VERSIONS
faccessat()
was added to Linux in kernel 2.6.16.
CONFORMING TO
POSIX.1-2008.
NOTES
See
openat(2)
for an explanation of the need for
faccessat().
Glibc Notes
The
AT_EACCESS
and
AT_SYMLINK_NOFOLLOW
flags are actually implemented within the glibc wrapper function for
faccessat().
If either of these flags are specified, then the wrapper function employs
fstatat(2)
to determine access permissions.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
