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<p class="level0"><a name="NAME"></a><h2 class="nroffsh">NAME</h2>
<p class="level0">pcap_setnonblock, pcap_getnonblock - set or get the state of non-blocking mode on a capture device <a name="SYNOPSIS"></a><h2 class="nroffsh">SYNOPSIS</h2>
<p class="level0"><pre class="level0">
&#35;include &lt;pcap/pcap.h&gt;
<pre class="level0">
char errbuf[PCAP_ERRBUF_SIZE];
int pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf);
int pcap_getnonblock(pcap_t *p, char *errbuf);
</pre>

<p class="level0"><a name="DESCRIPTION"></a><h2 class="nroffsh">DESCRIPTION</h2>
<p class="level0"><span Class="bold">pcap_setnonblock</span>() puts a capture handle into ``non-blocking&#39;&#39; mode, or takes it out of ``non-blocking&#39;&#39; mode, depending on whether the <span Class="emphasis">nonblock</span> argument is non-zero or zero.  It has no effect on ``savefiles&#39;&#39;. If there is an error, <span Class="bold">PCAP_ERROR</span> is returned and <span Class="emphasis">errbuf</span> is filled in with an appropriate error message; otherwise, <span Class="bold">0</span> is returned. 
<p class="level0">In ``non-blocking&#39;&#39; mode, an attempt to read from the capture descriptor with <span Class="bold">pcap_dispatch</span>(3PCAP) and <a Class="bold" href="./pcap_next_ex.html">pcap_next_ex</a>(3PCAP) will, if no packets are currently available to be read, return <span Class="bold">0</span> immediately rather than blocking waiting for packets to arrive. 
<p class="level0"><a Class="bold" href="./pcap_loop.html">pcap_loop</a>(3PCAP) will loop forever, consuming CPU time when no packets are currently available; <span Class="bold">pacp_dispatch</span>() should be used instead. <span Class="bold">pcap_next</span>(3PCAP) will return <span Class="bold">NULL</span> if there are no packets currently available to read; this is indistinguishable from an error, so <span Class="bold">pcap_next_ex</span>() should be used instead. 
<p class="level0">When first activated with <a Class="bold" href="./pcap_activate.html">pcap_activate</a>(3PCAP) or opened with <a Class="bold" href="./pcap_open_live.html">pcap_open_live</a>(3PCAP)<span Class="bold">,</span> a capture handle is not in ``non-blocking mode&#39;&#39;; a call to <span Class="bold">pcap_setnonblock</span>() is required in order to put it into ``non-blocking&#39;&#39; mode. <a name="RETURN"></a><h2 class="nroffsh">RETURN VALUE</h2>
<p class="level0"><span Class="bold">pcap_getnonblock</span>() returns the current ``non-blocking&#39;&#39; state of the capture descriptor; it always returns <span Class="bold">0</span> on ``savefiles&#39;&#39;. If called on a capture handle that has been created but not activated, <span Class="bold">PCAP_ERROR_NOT_ACTIVATED</span> is returned. If there is another error, <span Class="bold">PCAP_ERROR</span> is returned and <span Class="emphasis">errbuf</span> is filled in with an appropriate error message. 
<p class="level0"><span Class="emphasis">errbuf</span> is assumed to be able to hold at least <span Class="bold">PCAP_ERRBUF_SIZE</span> chars. <a name="SEE"></a><h2 class="nroffsh">SEE ALSO</h2>
<p class="level0"><a Class="bold" href="./pcap.html">pcap</a>(3PCAP), <a Class="bold" href="./pcap_next_ex.html">pcap_next_ex</a>(3PCAP), <a Class="bold" href="./pcap_geterr.html">pcap_geterr</a>(3PCAP) <p class="roffit">
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