faccessat — check user's permissions of a file relative to a directory file descriptor
#define _ATFILE_SOURCE #include <fcntl.h> /* Definition of AT_* constants */ #include <unistd.h>
int
faccessat( |
int | dirfd, |
| const char * | pathname, | |
| int | mode, | |
| int | flags); |
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_EACCESSPerform access checks using the effective user and
group IDs. By default, faccessat() uses the real IDs (like
access(2)).
AT_SYMLINK_NOFOLLOWIf pathname
is a symbolic link, do not dereference it: instead
return information about the link itself.
On success, (all requested permissions granted)
faccessat() returns 0. On
error, −1 is returned and errno is set to indicate the error.
The same errors that occur for access(2) can also occur
for faccessat(). The following
additional errors can occur for faccessat():
dirfd is not
a valid file descriptor.
Invalid flag specified in flags.
pathname is
relative and dirfd is a file
descriptor referring to a file other than a
directory.
This system call is non-standard but is proposed for inclusion in a future revision of POSIX.1.
See openat(2) for an
explanation of the need for faccessat().
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 2.79 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/.
|
This manpage is Copyright (C) 2006, Michael Kerrisk Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. |