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<h2 id="os_mbuf_pullup"><font color="#F2853F" style="font-size:24pt">os_mbuf_pullup</font></h2>
<div class="codehilite" style="background: #ffffff"><pre style="line-height: 125%;"><span></span><code><span style="color: #A90D91">struct</span> <span style="color: #3F6E75">os_mbuf</span> <span style="color: #000000">*os_mbuf_pullup</span>(<span style="color: #A90D91">struct</span> <span style="color: #3F6E75">os_mbuf</span> <span style="color: #000000">*om</span>, <span style="color: #A90D91">uint16_t</span> <span style="color: #000000">len</span>)
</code></pre></div>
<p>Rearrange an mbuf chain so that len bytes are contiguous, and in the data area of an mbuf (so that OS_MBUF_DATA() will work on a structure of size len.) Returns the resulting mbuf chain on success, free's it and returns NULL on failure.</p>
<p><br></p>
<h4 id="arguments">Arguments</h4>
<table>
<thead>
<tr>
<th>Arguments</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr>
<td>om</td>
<td>Pointer to mbuf</td>
</tr>
<tr>
<td>len</td>
<td>Length, in bytes, to pullup (make contiguous in mbuf)</td>
</tr>
</tbody>
</table>
<p><br></p>
<h4 id="returned-values">Returned values</h4>
<p>Pointer to mbuf at head of chain; NULL if not enough mbufs were available to accommodate <em>len</em> or if the requested pullup size was too large.</p>
<p><br></p>
<h4 id="notes">Notes</h4>
<p>Hopefully it is apparent to the user that you cannot pullup more bytes than the mbuf can accommodate. Pullup does not allocate more than one mbuf; the entire pullup length must be contained within a single mbuf.</p>
<p>The mbuf that is being pulled up into does not need to be a packet header mbuf; it can be a normal mbuf. The user should note that the maximum pullup length does depend on the type of mbuf being pulled up into (a packet header or normal mbuf).</p>
<p><br></p>
<h4 id="example">Example</h4>
<div class="codehilite" style="background: #ffffff"><pre style="line-height: 125%;"><span></span><code> <span style="color: #A90D91">struct</span> <span style="color: #3F6E75">os_mbuf</span> <span style="color: #000000">*om</span>;
<span style="color: #A90D91">struct</span> <span style="color: #3F6E75">os_mbuf</span> <span style="color: #000000">*tmp</span>;
<span style="color: #A90D91">struct</span> <span style="color: #3F6E75">my_header_struct</span> <span style="color: #000000">my_header</span>;
<span style="color: #177500">/* Make sure &quot;my_header&quot; is contiguous in the mbuf */</span>
<span style="color: #000000">tmp</span> <span style="color: #000000">=</span> <span style="color: #000000">os_mbuf_pullup</span>(<span style="color: #000000">om</span>, <span style="color: #A90D91">sizeof</span>(<span style="color: #000000">my_header_struct</span>));
<span style="color: #A90D91">if</span> (<span style="color: #000000">!tmp</span>) {
<span style="color: #177500">/* Pullup failed. The chain pointed to by *om has been freed */</span>
<span style="color: #A90D91">return</span> <span style="color: #1C01CE">-1</span>;
}
<span style="color: #177500">/* copy data from mbuf into header structure */</span>
<span style="color: #000000">memcpy</span>(<span style="color: #000000">&amp;my_header</span>, <span style="color: #000000">tmp-&gt;om_data</span>, <span style="color: #A90D91">sizeof</span>(<span style="color: #A90D91">struct</span> <span style="color: #3F6E75">my_header_struct</span>));
</code></pre></div>
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