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<table class="head">
<tr>
<td class="head-ltitle">VOP_GETEXTATTR(9)</td>
<td class="head-vol">Kernel Developer's Manual</td>
<td class="head-rtitle">VOP_GETEXTATTR(9)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">VOP_GETEXTATTR</code> —
<span class="Nd">retrieve named extended attribute from a vnode</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="In">#include
<<a class="In">sys/param.h</a>></code>
<br/>
<code class="In">#include <<a class="In">sys/vnode.h</a>></code>
<br/>
<code class="In">#include <<a class="In">sys/extattr.h</a>></code></p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">VOP_GETEXTATTR</code>(<var class="Fa">struct vnode *vp</var>,
<var class="Fa">int attrnamespace</var>, <var class="Fa">const char
*name</var>, <var class="Fa">struct uio *uio</var>, <var class="Fa">size_t
*size</var>, <var class="Fa">struct ucred *cred</var>,
<var class="Fa">struct thread *td</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">This vnode call may be used to retrieve a specific named extended
attribute from a file or directory.</p>
<p class="Pp">Its arguments are:</p>
<dl class="Bl-tag">
<dt><var class="Fa">vp</var></dt>
<dd>The vnode of the file or directory.</dd>
<dt><var class="Fa">attrnamespace</var></dt>
<dd>Integer constant indicating which extended attribute namespace the
attribute name is present in.</dd>
<dt><var class="Fa">name</var></dt>
<dd>Pointer to a null-terminated character string containing the attribute
name.</dd>
<dt><var class="Fa">uio</var></dt>
<dd>The location of the data to be read.</dd>
<dt><var class="Fa">size</var></dt>
<dd>If not <code class="Dv">NULL</code>, on return it will contain the number
of bytes required to read all of the attribute data. In most cases
<var class="Fa">uio</var> will be <code class="Dv">NULL</code> when
<var class="Fa">size</var> is not, and vice versa.</dd>
<dt><var class="Fa">cred</var></dt>
<dd>The user credentials to use in authorizing the request.</dd>
<dt><var class="Fa">td</var></dt>
<dd>The thread requesting the extended attribute.</dd>
</dl>
<p class="Pp">The <var class="Fa">cred</var> pointer may be
<code class="Dv">NULL</code> to indicate that access control checks are not
to be performed, if possible. This <var class="Fa">cred</var> setting might
be used to allow the kernel to authorize extended attribute retrieval that
the active process might not be permitted to do.</p>
<p class="Pp">Extended attribute semantics may vary by file system implementing
the call. More information on extended attributes may be found in
<a class="Xr">extattr(9)</a>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="LOCKS"><a class="permalink" href="#LOCKS">LOCKS</a></h1>
<p class="Pp">The vnode will be locked on entry and should remain locked on
return.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="RETURN_VALUES"><a class="permalink" href="#RETURN_VALUES">RETURN
VALUES</a></h1>
<p class="Pp">On success, zero will be returned, and the uio structure will be
updated to reflect data read. Otherwise, an appropriate error code is
returned.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="ERRORS"><a class="permalink" href="#ERRORS">ERRORS</a></h1>
<dl class="Bl-tag">
<dt id="ENOATTR">[<a class="permalink" href="#ENOATTR"><code class="Er">ENOATTR</code></a>]</dt>
<dd>The requested attribute was not defined for this vnode.</dd>
<dt id="EACCES">[<a class="permalink" href="#EACCES"><code class="Er">EACCES</code></a>]</dt>
<dd>The caller does not have the appropriate privilege.</dd>
<dt id="ENXIO">[<a class="permalink" href="#ENXIO"><code class="Er">ENXIO</code></a>]</dt>
<dd>The request was not valid in this file system for the specified vnode and
attribute name.</dd>
<dt id="ENOMEM">[<a class="permalink" href="#ENOMEM"><code class="Er">ENOMEM</code></a>]</dt>
<dd>Sufficient memory is not available to fulfill the request.</dd>
<dt id="EFAULT">[<a class="permalink" href="#EFAULT"><code class="Er">EFAULT</code></a>]</dt>
<dd>The uio structure refers to an invalid userspace address.</dd>
<dt id="EINVAL">[<a class="permalink" href="#EINVAL"><code class="Er">EINVAL</code></a>]</dt>
<dd>The <var class="Fa">name</var>, <var class="Fa">namespace</var>, or
<var class="Fa">uio</var> argument is invalid.</dd>
<dt id="EOPNOTSUPP">[<a class="permalink" href="#EOPNOTSUPP"><code class="Er">EOPNOTSUPP</code></a>]</dt>
<dd>The file system does not support
<code class="Fn">VOP_GETEXTATTR</code>().</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">extattr(9)</a>, <a class="Xr">vnode(9)</a>,
<a class="Xr">VOP_LISTEXTATTR(9)</a>,
<a class="Xr">VOP_SETEXTATTR(9)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1>
<p class="Pp">By passing in the empty string as the attribute name, some file
systems will return a list of defined names on the target vnode for the
requested namespace. This is a bad API, and will be replaced by an explicit
VOP.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">December 23, 1999</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
