linux man page for faccessat

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 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.

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

COLOPHON
       This page is part of release 3.27 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								    2009-12-13							      FACCESSAT(2)