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FACCESSAT(2)			    Linux Programmer's Manual			     FACCESSAT(2)

NAME
       faccessat - check user's permissions of a file relative to a directory file descriptor

SYNOPSIS
       #include <fcntl.h> /* Definition of AT_* constants */
       #include <unistd.h>

       int faccessat(int dirfd, const char *pathname, int mode, int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       faccessat():
	   Since glibc 2.10:
	       _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
	   Before glibc 2.10:
	       _ATFILE_SOURCE

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  path-
       name).

       If  pathname  is relative and dirfd is the special value AT_FDCWD, then pathname is inter-
       preted 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,  facces-
	      sat() 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; library support was added to glibc in
       version 2.4.

CONFORMING TO
       POSIX.1-2008.

NOTES
       See openat(2) for an explanation of the need for faccessat().

       Warning: faccessat() is subject to the same kinds of races as access(2) and euidaccess(3).

   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 wrap-
       per function employs fstatat(2) to determine access permissions.

SEE ALSO
       access(2), openat(2), euidaccess(3), credentials(7), path_resolution(7), symlink(7)

COLOPHON
       This page is part of release 3.55 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/.

Linux					    2012-05-04				     FACCESSAT(2)
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