faccessat(2)

1FACCESSAT(2)               Linux Programmer's Manual              FACCESSAT(2)
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NAME

6       faccessat  - check user's permissions of a file relative to a directory
7       file descriptor
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SYNOPSIS

10       #include <fcntl.h> /* Definition of AT_* constants */
11       #include <unistd.h>
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13       int faccessat(int dirfd, const char *pathname, int mode, int flags);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       faccessat():
18           Since glibc 2.10:
19               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
20           Before glibc 2.10:
21               _ATFILE_SOURCE
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DESCRIPTION

24       The faccessat() system  call  operates  in  exactly  the  same  way  as
25       access(2), except for the differences described in this manual page.
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27       If  the  pathname given in pathname is relative, then it is interpreted
28       relative to the directory referred to  by  the  file  descriptor  dirfd
29       (rather  than  relative to the current working directory of the calling
30       process, as is done by access(2) for a relative pathname).
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32       If pathname is relative and dirfd is the special value  AT_FDCWD,  then
33       pathname  is  interpreted  relative to the current working directory of
34       the calling process (like access(2)).
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36       If pathname is absolute, then dirfd is ignored.
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38       flags is constructed by ORing together zero or more  of  the  following
39       values:
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41       AT_EACCESS
42              Perform  access  checks  using the effective user and group IDs.
43              By default, faccessat() uses the real IDs (like access(2)).
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45       AT_SYMLINK_NOFOLLOW
46              If pathname is a symbolic link, do not dereference  it:  instead
47              return information about the link itself.
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RETURN VALUE

50       On  success, (all requested permissions granted) faccessat() returns 0.
51       On error, -1 is returned and errno is set to indicate the error.
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ERRORS

54       The same errors that occur for access(2) can  also  occur  for  facces‐
55       sat().  The following additional errors can occur for faccessat():
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57       EBADF  dirfd is not a valid file descriptor.
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59       EINVAL Invalid flag specified in flags.
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61       ENOTDIR
62              pathname is relative and dirfd is a file descriptor referring to
63              a file other than a directory.
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VERSIONS

66       faccessat() was added to Linux in kernel 2.6.16;  library  support  was
67       added to glibc in version 2.4.
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CONFORMING TO

70       POSIX.1-2008.
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NOTES

73       See openat(2) for an explanation of the need for faccessat().
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75       Warning: faccessat() is subject to the same kinds of races as access(2)
76       and euidaccess(3).
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78   Glibc notes
79       The AT_EACCESS and AT_SYMLINK_NOFOLLOW flags are  actually  implemented
80       within  the glibc wrapper function for faccessat().  If either of these
81       flags are specified, then the wrapper function  employs  fstatat(2)  to
82       determine access permissions.
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COLOPHON

89       This page is part of release 3.53 of the Linux  man-pages  project.   A
90       description  of  the project, and information about reporting bugs, can
91       be found at http://www.kernel.org/doc/man-pages/.
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95Linux                             2012-05-04                      FACCESSAT(2)