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<table class="head">
<tr>
<td class="head-ltitle">LUA(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">LUA(4)</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">lua</code> — <span class="Nd">control
in-kernel Lua states</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">lua*</code></p>
<p class="Pp">
<br/>
<code class="In">#include <<a class="In">sys/types.h</a>></code>
<br/>
<code class="In">#include <<a class="In">sys/lua.h</a>></code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">lua</code> device allows to create, control,
and delete Lua states in the kernel through an <a class="Xr">ioctl(2)</a>
interface. Moreover, <code class="Nm">lua</code> can be used to load Lua
scripts into a Lua state and to assign modules to an existing state, i.e.
perform the equivalent of the Lua command <i class="Em">require</i>.
<code class="Nm">lua</code> is also used to retrieve information about
currently active Lua states.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="LUA_MODULES"><a class="permalink" href="#LUA_MODULES">LUA
MODULES</a></h1>
<p class="Pp">Lua modules are used to provide functionality to Lua scripts not
available in the language itself, e.g. to access core kernel functionality
like printing text on the console. Unlike in user space Lua, where Lua
modules are files in the filesystem, modules must be provided to
<code class="Nm">lua</code> in the form of loadable kernel modules that
register their functionality with <code class="Nm">lua</code>. Modules are
loaded using the <code class="Ic">require</code> Lua command; whether this
command is available or not is controlled by a <a class="Xr">sysctl(8)</a>
variable. <code class="Nm">lua</code> by default tries to load a kernel
module named
<a class="permalink" href="#luafoo.kmod"><i class="Em" id="luafoo.kmod">luafoo.kmod</i></a>
when it encounters the Lua command <i class="Em">require 'foo'</i>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYSCTL_VARIABLES"><a class="permalink" href="#SYSCTL_VARIABLES">SYSCTL
VARIABLES</a></h1>
<p class="Pp">The operation of <code class="Nm">lua</code> can be controlled by
means of the following <a class="Xr">sysctl(8)</a> variables:</p>
<dl class="Bl-tag">
<dt id="kern.lua.autoload"><a class="permalink" href="#kern.lua.autoload"><code class="Dv">kern.lua.autoload</code></a></dt>
<dd>When set to 1, <code class="Nm">lua</code> tries to autoload kernel
modules.
<p class="Pp">The default value is 1.</p>
</dd>
<dt id="kern.lua.bytecode"><a class="permalink" href="#kern.lua.bytecode"><code class="Dv">kern.lua.bytecode</code></a></dt>
<dd>When set to 1, loading of Lua bytecode is allowed.
<p class="Pp">The default value is 0.</p>
</dd>
<dt id="kern.lua.maxcount"><a class="permalink" href="#kern.lua.maxcount"><code class="Dv">kern.lua.maxcount</code></a></dt>
<dd>When set to a value > 0, <code class="Nm">lua</code> limits the number
of instructions executed to this number.
<p class="Pp">The default value is 0.</p>
</dd>
<dt id="kern.lua.require"><a class="permalink" href="#kern.lua.require"><code class="Dv">kern.lua.require</code></a></dt>
<dd>When set to 1, enables the <i class="Em">require</i> command in Lua.
<p class="Pp">The default value is 1.</p>
</dd>
<dt id="kern.lua.verbose"><a class="permalink" href="#kern.lua.verbose"><code class="Dv">kern.lua.verbose</code></a></dt>
<dd>When set to a value > 0, verbosity is increased.
<p class="Pp">The default value is 0.</p>
</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="IOCTL_INTERFACE"><a class="permalink" href="#IOCTL_INTERFACE">IOCTL
INTERFACE</a></h1>
<p class="Pp">The following structures and constants are defined in the
<code class="In"><<a class="In">sys/lua.h</a>></code> header file:</p>
<p class="Pp"></p>
<dl class="Bl-tag Bl-compact">
<dt id="LUAINFO(struct"><a class="permalink" href="#LUAINFO(struct"><code class="Dv">LUAINFO(struct
lua_info)</code></a></dt>
<dd>Returns information about the <code class="Nm">lua</code> states in the
<var class="Fa">lua_info</var> structure:
<div class="Bd Pp Li">
<pre>#define MAX_LUA_NAME 16
#define MAX_LUA_DESC 64
struct lua_state_info {
char name[MAX_LUA_NAME];
char desc[MAX_LUA_DESC];
bool user;
};
struct lua_info {
int num_states; /* total number of Lua states */
struct lua_state_info *states;
};</pre>
</div>
<p class="Pp"></p>
</dd>
<dt id="LUACREATE(struct"><a class="permalink" href="#LUACREATE(struct"><code class="Dv">LUACREATE(struct
lua_create)</code></a></dt>
<dd>Create a new named Lua state with name and description in the
<var class="Fa">lua_create</var> structure:
<div class="Bd Pp Li">
<pre>struct lua_create {
char name[MAX_LUA_NAME];
char desc[MAX_LUA_DESC];
};</pre>
</div>
<p class="Pp"></p>
</dd>
<dt id="LUADESTROY(struct"><a class="permalink" href="#LUADESTROY(struct"><code class="Dv">LUADESTROY(struct
lua_create)</code></a></dt>
<dd>Destroy a named Lua state.
<p class="Pp"></p>
</dd>
<dt id="LUAREQUIRE(struct"><a class="permalink" href="#LUAREQUIRE(struct"><code class="Dv">LUAREQUIRE(struct
lua_require)</code></a></dt>
<dd>Perform the equivalent of the Lua command <i class="Em">require</i> in a
named state. The name of the state and of the module name is passed in the
<var class="Fa">lua_require</var> structure:
<div class="Bd Pp Li">
<pre>#define LUA_MAX_MODNAME 32
struct lua_require {
char state[MAX_LUA_NAME];
char module[LUA_MAX_MODNAME];
};</pre>
</div>
<p class="Pp"></p>
</dd>
<dt id="LUALOAD(struct"><a class="permalink" href="#LUALOAD(struct"><code class="Dv">LUALOAD(struct
lua_load)</code></a></dt>
<dd>Load Lua code from the filesystem into a named Lua state. The name of the
state and the path to the Lua code are passed in the
<var class="Fa">lua_load</var> structure:
<div class="Bd Pp Li">
<pre>struct lua_load {
char state[MAX_LUA_NAME];
char path[MAXPATHLEN];
};</pre>
</div>
<p class="Pp">The path element of the <var class="Fa">lua_load</var>
structure must contain at least one ‘/’ character.</p>
</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="FILES"><a class="permalink" href="#FILES">FILES</a></h1>
<dl class="Bl-tag Bl-compact">
<dt>/dev/lua</dt>
<dd>Lua device file.</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">ioctl(2)</a>, <a class="Xr">luactl(8)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">lua</code> device first appeared in
<span class="Ux">NetBSD 7.0</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">The <code class="Nm">lua</code> driver was written by
<span class="An">Marc Balmer</span>
<<a class="Mt" href="mailto:mbalmer@NetBSD.org">mbalmer@NetBSD.org</a>>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="CAVEATS"><a class="permalink" href="#CAVEATS">CAVEATS</a></h1>
<p class="Pp">The <code class="Nm">lua</code> device is experimental.
Incompatible changes might be made in the future.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">July 25, 2014</td>
<td class="foot-os">NetBSD 10.1</td>
</tr>
</table>
|
