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lgetxattr.html
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<!-- Creator : groff version 1.22.4 -->
<!-- CreationDate: Wed Jan 29 11:25:55 2020 -->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta name="generator" content="groff -Thtml, see www.gnu.org">
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<meta name="Content-Style" content="text/css">
<style type="text/css">
p { margin-top: 0; margin-bottom: 0; vertical-align: top }
pre { margin-top: 0; margin-bottom: 0; vertical-align: top }
table { margin-top: 0; margin-bottom: 0; vertical-align: top }
h1 { text-align: center }
</style>
<title>GETXATTR</title>
</head>
<body>
<h1 align="center">GETXATTR</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#RETURN VALUE">RETURN VALUE</a><br>
<a href="#ERRORS">ERRORS</a><br>
<a href="#VERSIONS">VERSIONS</a><br>
<a href="#CONFORMING TO">CONFORMING TO</a><br>
<a href="#EXAMPLE">EXAMPLE</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<a href="#COLOPHON">COLOPHON</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">getxattr,
lgetxattr, fgetxattr - retrieve an extended attribute
value</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>#include
<sys/types.h> <br>
#include <sys/xattr.h></b></p>
<p style="margin-left:11%; margin-top: 1em"><b>ssize_t
getxattr(const char *</b><i>path</i><b>, const
char *</b><i>name</i><b>, <br>
void *</b><i>value</i><b>, size_t</b> <i>size</i><b>);
<br>
ssize_t lgetxattr(const char *</b><i>path</i><b>, const
char *</b><i>name</i><b>, <br>
void *</b><i>value</i><b>, size_t</b> <i>size</i><b>);
<br>
ssize_t fgetxattr(int</b> <i>fd</i><b>, const
char *</b><i>name</i><b>, <br>
void *</b><i>value</i><b>, size_t</b>
<i>size</i><b>);</b></p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">Extended
attributes are <i>name</i>:<i>value</i> 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 <b>stat</b>(2)
data). A complete overview of extended attributes concepts
can be found in <b>xattr</b>(7).</p>
<p style="margin-left:11%; margin-top: 1em"><b>getxattr</b>()
retrieves the value of the extended attribute identified by
<i>name</i> and associated with the given <i>path</i> in the
filesystem. The attribute value is placed in the buffer
pointed to by <i>value</i>; <i>size</i> specifies the size
of that buffer. The return value of the call is the number
of bytes placed in <i>value</i>.</p>
<p style="margin-left:11%; margin-top: 1em"><b>lgetxattr</b>()
is identical to <b>getxattr</b>(), except in the case of a
symbolic link, where the link itself is interrogated, not
the file that it refers to.</p>
<p style="margin-left:11%; margin-top: 1em"><b>fgetxattr</b>()
is identical to <b>getxattr</b>(), only the open file
referred to by <i>fd</i> (as returned by <b>open</b>(2)) is
interrogated in place of <i>path</i>.</p>
<p style="margin-left:11%; margin-top: 1em">An extended
attribute <i>name</i> is a 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 that was assigned using <b>setxattr</b>(2).</p>
<p style="margin-left:11%; margin-top: 1em">If <i>size</i>
is specified as zero, these calls return the current size of
the named extended attribute (and leave <i>value</i>
unchanged). This can be used to determine the size of the
buffer that should be supplied in a subsequent call. (But,
bear in mind that there is a possibility that the attribute
value may change between the two calls, so that it is still
necessary to check the return status from the second
call.)</p>
<h2>RETURN VALUE
<a name="RETURN VALUE"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">On success,
these calls return a nonnegative value which is the size (in
bytes) of the extended attribute value. On failure, -1 is
returned and <i>errno</i> is set appropriately.</p>
<h2>ERRORS
<a name="ERRORS"></a>
</h2>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p style="margin-top: 1em"><b>E2BIG</b></p></td>
<td width="4%"></td>
<td width="78%">
<p style="margin-top: 1em">The size of the attribute value
is larger than the maximum size allowed; the attribute
cannot be retrieved. This can happen on filesystems that
support very large attribute values such as NFSv4, for
example.</p> </td></tr>
</table>
<p style="margin-left:11%;"><b>ENODATA</b></p>
<p style="margin-left:22%;">The named attribute does not
exist, or the process has no access to this attribute.</p>
<p style="margin-left:11%;"><b>ENOTSUP</b></p>
<p style="margin-left:22%;">Extended attributes are not
supported by the filesystem, or are disabled.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ERANGE</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>The <i>size</i> of the <i>value</i> buffer is too small
to hold the result.</p></td></tr>
</table>
<p style="margin-left:11%; margin-top: 1em">In addition,
the errors documented in <b>stat</b>(2) can also occur.</p>
<h2>VERSIONS
<a name="VERSIONS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">These system
calls have been available on Linux since kernel 2.4; glibc
support is provided since version 2.3.</p>
<h2>CONFORMING TO
<a name="CONFORMING TO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">These system
calls are Linux-specific.</p>
<h2>EXAMPLE
<a name="EXAMPLE"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">See
<b>listxattr</b>(2).</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>getfattr</b>(1),
<b>setfattr</b>(1), <b>listxattr</b>(2), <b>open</b>(2),
<b>removexattr</b>(2), <b>setxattr</b>(2), <b>stat</b>(2),
<b>symlink</b>(7), <b>xattr</b>(7)</p>
<h2>COLOPHON
<a name="COLOPHON"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">This page is
part of release 5.02 of the Linux <i>man-pages</i> project.
A description of the project, information about reporting
bugs, and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.</p>
<hr>
</body>
</html>