NetBSDのLuaカーネルモジュールサンプルです。

netbsd_lua_kern_module_sample.c

/*-
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/lua.h>
#include <sys/module.h>

#include <lua.h>
#include <lauxlib.h>

/*
 * To use this device you need to do:
 *     mknod /dev/happy c 210 0
 */

dev_type_open(luaread_open);
dev_type_close(luaread_close);
dev_type_read(luaread_read);

static struct cdevsw luaread_cdevsw = {
	.d_open = luaread_open,
	.d_close = luaread_close,
	.d_read = luaread_read,
	.d_write = nowrite,
	.d_ioctl = noioctl,
	.d_stop = nostop,
	.d_tty = notty,
	.d_poll = nopoll,
	.d_mmap = nommap,
	.d_kqfilter = nokqfilter,
	.d_discard = nodiscard,
	.d_flag = D_OTHER
};


struct luaread_softc {
	int		 refcnt;
	unsigned	 last;
	klua_State	*kL;
};

static struct luaread_softc sc;

static int
luaopen_systm(lua_State *L)
{
	const luaL_Reg systm_lib[] = {
		{ NULL, NULL }
	};
	luaL_newlib(sc.kL->L, systm_lib);

	lua_pushstring(sc.kL->L, copyright);
	lua_setfield(sc.kL->L, -2, "copyright");

	return 1;
}

int
luaread_open(dev_t self __unused, int flag __unused, int mode __unused,
           struct lwp *l __unused)
{
	printf("-=> luaread_open()\n");

	if (sc.refcnt > 0)
		return EBUSY;

	sc.last = 0;
	++sc.refcnt;

	return 0;
}

int
luaread_close(dev_t self __unused, int flag __unused, int mode __unused,
            struct lwp *l __unused)
{
	printf("-=> luaread_close()\n");

	--sc.refcnt;

	return 0;
}

int
luaread_read(dev_t self __unused, struct uio *uio, int flags __unused)
{
	int len;
	int e;

	printf("-=> luaread_read()\n");

	klua_lock(sc.kL);
	lua_getglobal(sc.kL->L, "myread");

        if (!lua_isfunction(sc.kL->L, -1)) {
		printf("-=> fail: lua_isfunction()\n");

		lua_pop(sc.kL->L, 1);
		klua_unlock(sc.kL);
		return -1;
        }

	if (lua_pcall(sc.kL->L, 0 /* args */, 1 /* res */, 0) != 0) {
		printf("-=> fail: lua_pcall()\n");

		lua_pop(sc.kL->L, 2);
		klua_unlock(sc.kL);
		return -1;
        }

        if (!lua_isstring(sc.kL->L, -1)) {
		printf("-=> fail: lua_isstring()\n");

		lua_pop(sc.kL->L, 2);
		klua_unlock(sc.kL);
		return -1;
        }

	char line[256];
	strncpy(line, lua_tostring(sc.kL->L, -1), 254);
	line[255] = '\0';

	/* Send it to User-Space */
	if ((e = uiomove(line, len, uio)))
		return e;

	return 0;
}

MODULE(MODULE_CLASS_MISC, luaread, "lua");

static int
luaread_modcmd(modcmd_t cmd, void *arg __unused)
{
	/* The major should be verified and changed if needed to avoid
	 * conflicts with other devices. */
	int cmajor = 210, bmajor = -1;

	switch (cmd) {
	case MODULE_CMD_INIT:
		printf("-=> MODULE_CMD_INIT\n"); // XXX debug

		klua_mod_register("luaread", luaopen_systm);

		if (devsw_attach("luaread", NULL, &bmajor, &luaread_cdevsw,
		                 &cmajor))
			return ENXIO;
		if ((sc.kL = kluaL_newstate("luaread",
		                            "Lua read/write sample",
		                            IPL_NONE)) == NULL) {
			devsw_detach(NULL, &luaread_cdevsw);
			return ENXIO;
		}

		return 0;
	case MODULE_CMD_FINI:
		if (sc.refcnt > 0)
			return EBUSY;

		klua_mod_unregister("luaread");
		klua_close(sc.kL);

		devsw_detach(NULL, &luaread_cdevsw);

		return 0;
	default:
		return ENOTTY;
	}
}