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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>usb_string</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The Linux-USB Host Side API" /><link rel="up" href="ch05.html" title="Chapter 5. USB Core APIs" /><link rel="prev" href="re65.html" title="usb_get_descriptor" /><link rel="next" href="re67.html" title="usb_get_status" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>usb_string</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re65.html">Prev</a> </td><th width="60%" align="center">Chapter 5. USB Core APIs</th><td width="20%" align="right"> <a accesskey="n" href="re67.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="usb_string"><a id="API-usb-string"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_string —
returns UTF-8 version of a string descriptor
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">usb_string </b>(</code></td><td>struct usb_device * <var class="pdparam">dev</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">index</var>, </td></tr><tr><td> </td><td>char * <var class="pdparam">buf</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id3111690"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>dev</code></em></span></dt><dd><p>
the device whose string descriptor is being retrieved
</p></dd><dt><span class="term"><em class="parameter"><code>index</code></em></span></dt><dd><p>
the number of the descriptor
</p></dd><dt><span class="term"><em class="parameter"><code>buf</code></em></span></dt><dd><p>
where to put the string
</p></dd><dt><span class="term"><em class="parameter"><code>size</code></em></span></dt><dd><p>
how big is <span class="quote">“<span class="quote">buf</span>”</span>?
</p></dd></dl></div></div><div class="refsect1" title="Context"><a id="id3111769"></a><h2>Context</h2><p>
!in_interrupt ()
</p></div><div class="refsect1" title="Description"><a id="id3111778"></a><h2>Description</h2><p>
This converts the UTF-16LE encoded strings returned by devices, from
<code class="function">usb_get_string_descriptor</code>, to null-terminated UTF-8 encoded ones
that are more usable in most kernel contexts. Note that this function
chooses strings in the first language supported by the device.
</p><p>
This call is synchronous, and may not be used in an interrupt context.
</p><p>
Returns length of the string (>= 0) or usb_control_msg status (< 0).
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re65.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch05.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re67.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>usb_get_descriptor</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>usb_get_status</span></td></tr></table></div></body></html>
