.\" Copyright (C) Andreas Gruenbacher, February 2001
.\" Copyright (C) Silicon Graphics Inc, September 2001
.\"
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.\"
.TH GETXATTR 2 2013-01-19 "Linux" "Linux Programmer's Manual"
.SH NAME
getxattr, lgetxattr, fgetxattr \- retrieve an extended attribute value
.SH SYNOPSIS
.fam C
.nf
.B #include <sys/types.h>
.B #include <attr/xattr.h>
.sp
.BI "ssize_t getxattr(const char\ *" path ", const char\ *" name ,
.BI "                 void\ *" value ", size_t " size );
.BI "ssize_t lgetxattr(const char\ *" path ", const char\ *" name ,
.BI "                 void\ *" value ", size_t " size );
.BI "ssize_t fgetxattr(int " fd ", const char\ *" name ,
.BI "                 void\ *" value ", size_t " size );
.fi
.fam T
.SH DESCRIPTION
Extended attributes are
.IR name :\c
.I value
pairs associated with inodes (files, directories, symbolic links, etc.).
They are extensions to the normal attributes which are associated
with all inodes in the system (i.e., the
.BR stat (2)
data).
A complete overview of extended attributes concepts can be found in
.BR attr (5).
.PP
.BR getxattr ()
retrieves the
.I value
of the extended attribute identified by
.I name
and associated with the given
.I path
in the file system.
The length of the attribute
.I value
is returned.
.PP
.BR lgetxattr ()
is identical to
.BR getxattr (),
except in the case of a symbolic link, where the link itself is
interrogated, not the file that it refers to.
.PP
.BR fgetxattr ()
is identical to
.BR getxattr (),
only the open file referred to by
.I fd
(as returned by
.BR open (2))
is interrogated in place of
.IR path .
.PP
An extended attribute
.I name
is a simple null-terminated string.
The name includes a namespace prefix; there may be several, disjoint
namespaces associated with an individual inode.
The value of an extended attribute is a chunk of arbitrary textual or
binary data of specified length.
.PP
An empty buffer of
.I size
zero can be passed into these calls to return the current size of the
named extended attribute, which can be used to estimate the size of a
buffer which is sufficiently large to hold the value associated with
the extended attribute.
.PP
The interface is designed to allow guessing of initial buffer
sizes, and to enlarge buffers when the return value indicates
that the buffer provided was too small.
.SH RETURN VALUE
On success, a positive number is returned indicating the size of the
extended attribute value.
On failure, \-1 is returned and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B ENOATTR
The named attribute does not exist, or the process has no access to
this attribute.
.RB ( ENOATTR
is defined to be a synonym for
.BR ENODATA
in
.IR <attr/xattr.h> .)
.TP
.B ENOTSUP
Extended attributes are not supported by the file system, or are disabled.
.TP
.B ERANGE
The
.I size
of the
.I value
buffer is too small to hold the result.
.PP
In addition, the errors documented in
.BR stat (2)
can also occur.
.SH VERSIONS
These system calls have been available on Linux since kernel 2.4;
glibc support is provided since version 2.3.
.SH CONFORMING TO
These system calls are Linux-specific.
.\" .SH AUTHORS
.\" Andreas Gruenbacher,
.\" .RI < a.gruenbacher@computer.org >
.\" and the SGI XFS development team,
.\" .RI < linux-xfs@oss.sgi.com >.
.\" Please send any bug reports or comments to these addresses.
.SH SEE ALSO
.BR getfattr (1),
.BR setfattr (1),
.BR listxattr (2),
.BR open (2),
.BR removexattr (2),
.BR setxattr (2),
.BR stat (2),
.BR attr (5),
.BR symlink (7)