man2/fstatat.2

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.TH FSTATAT 2 2012-05-04 "Linux" "Linux Programmer's Manual"
.SH NAME
fstatat \- get file status relative to a directory file descriptor
.SH SYNOPSIS
.nf
.B #include <fcntl.h>           /* Definition of AT_* constants */
.B #include <sys/stat.h>
.sp
.BI "int fstatat(int " dirfd ", const char *" pathname ", struct stat *" \
buf ,
.BI "            int " flags );
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR fstatat ():
.PD 0
.ad l
.RS 4
.TP 4
Since glibc 2.10:
_XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
.TP
Before glibc 2.10:
_ATFILE_SOURCE
.RE
.ad
.PD
.SH DESCRIPTION
The
.BR fstatat ()
system call operates in exactly the same way as
.BR stat (2),
except for the differences described in this manual page.

If the pathname given in
.I pathname
is relative, then it is interpreted relative to the directory
referred to by the file descriptor
.I dirfd
(rather than relative to the current working directory of
the calling process, as is done by
.BR stat (2)
for a relative pathname).

If
.I pathname
is relative and
.I dirfd
is the special value
.BR AT_FDCWD ,
then
.I pathname
is interpreted relative to the current working
directory of the calling process (like
.BR stat (2)).

If
.I pathname
is absolute, then
.I dirfd
is ignored.

.I flags
can either be 0, or include one or more of the following flags ORed:
.TP
.BR AT_NO_AUTOMOUNT " (since Linux 2.6.38)"
Don't automount the terminal ("basename") component of
.I pathname
if it is a directory that is an automount point.
This allows the caller to gather attributes of an automount point
(rather than the location it would mount).
This flag can be used in tools that scan directories
to prevent mass-automounting of a directory of automount points.
The
.B AT_NO_AUTOMOUNT
flag has no effect if the mount point has already been mounted over.
.TP
.B AT_SYMLINK_NOFOLLOW
If
.I pathname
is a symbolic link, do not dereference it:
instead return information about the link itself, like
.BR lstat (2).
(By default,
.BR fstatat ()
dereferences symbolic links, like
.BR stat (2).)
.SH "RETURN VALUE"
On success,
.BR fstatat ()
returns 0.
On error, \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
The same errors that occur for
.BR stat (2)
can also occur for
.BR fstatat ().
The following additional errors can occur for
.BR fstatat ():
.TP
.B EBADF
.I dirfd
is not a valid file descriptor.
.TP
.B EINVAL
Invalid flag specified in
.IR flags .
.TP
.B ENOTDIR
.I pathname
is relative and
.I dirfd
is a file descriptor referring to a file other than a directory.
.SH VERSIONS
.BR fstatat ()
was added to Linux in kernel 2.6.16;
library support was added to glibc in version 2.4.
.SH "CONFORMING TO"
POSIX.1-2008.
A similar system call exists on Solaris.
.SH NOTES
See
.BR openat (2)
for an explanation of the need for
.BR fstatat ().

The underlying system call employed by the glibc
.BR fstatat ()
wrapper function is actually called
.BR fstatat64 ().
.SH "SEE ALSO"
.BR openat (2),
.BR stat (2),
.BR path_resolution (7),
.BR symlink (7)