9.4 ×Ö·ûÉ豸

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¡¡¡¡Õâ¸ö¼òµ¥µÄαÉ豸Àý×Ó»á¼ÇסÄãд¸øËüµÄÈκÎÖµ£¬²¢ÇÒµ±Äã¶ÁÈ¡ËüµÄʱºò »á½«ÕâЩֵ·µ»Ø¸øÄã¡£ÏÂÃæÏÔʾÁËÁ½¸ö°æ±¾£¬Ò»¸öÊÊÓÃÓÚFreeBSD 4.X£¬ Ò»¸öÊÊÓÃÓÚFreeBSD 5.X¡£

Àý 9-1. ÊÊÓÃÓÚFreeBSD 4.XµÄ»ØÏÔαÉ豸Çý¶¯³ÌÐòʵÀý

/*
 * ¼òµ¥¡®echo¡¯Î±É豸KLD
 *
 * Murray Stokely
 */

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

#include <sys/types.h>
#include <sys/module.h>
#include <sys/systm.h>  /* uprintf */
#include <sys/errno.h>
#include <sys/param.h>  /* kernel.hÖÐÓõ½µÄ¶¨Òå */
#include <sys/kernel.h> /* Ä£¿é³õʼ»¯ÖÐʹÓõÄÀàÐÍ */
#include <sys/conf.h>   /* cdevsw½á¹¹ */
#include <sys/uio.h>    /* uio½á¹¹ */
#include <sys/malloc.h>

#define BUFFERSIZE 256

/* º¯ÊýÔ­ÐÍ */
d_open_t	echo_open;
d_close_t	echo_close;
d_read_t	echo_read;
d_write_t	echo_write;

/* ×Ö·ûÉ豸Èë¿Úµã */
static struct cdevsw echo_cdevsw = {
	echo_open,
	echo_close,
	echo_read,
	echo_write,
	noioctl,
	nopoll,
	nommap,
	nostrategy,
	"echo",
	33,              /* Ϊlkms±£Áô - /usr/src/sys/conf/majors */
	nodump,
	nopsize,
	D_TTY,
	-1
};

typedef struct s_echo {
	char msg[BUFFERSIZE];
	int len;
} t_echo;

/* ±äÁ¿ */
static dev_t sdev;
static int count;
static t_echo *echomsg;

MALLOC_DECLARE(M_ECHOBUF);
MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");

/*
 * Õâ¸öº¯Êý±»kld[un]load(2)ϵͳµ÷ÓÃÀ´µ÷Óã¬
 * ÒÔ¾ö¶¨¼ÓÔØºÍÐ¶ÔØÄ£¿éʱÐèÒª²ÉÈ¡µÄ¶¯×÷¡£
 */

static int
echo_loader(struct module *m, int what, void *arg)
{
	int err = 0;

	switch (what) {
	case MOD_LOAD:                /* kldload */
		sdev = make_dev(&echo_cdevsw,
		    0,
		    UID_ROOT,
		    GID_WHEEL,
		    0600,
		    "echo");
		/* kmalloc·ÖÅ乩Çý¶¯³ÌÐòʹÓõÄÄÚ´æ */
		MALLOC(echomsg, t_echo *, sizeof(t_echo), M_ECHOBUF, M_WAITOK);
		printf("Echo device loaded.\n");
		break;
	case MOD_UNLOAD:
		destroy_dev(sdev);
		FREE(echomsg,M_ECHOBUF);
		printf("Echo device unloaded.\n");
		break;
	default:
		err = EOPNOTSUPP;
		break;
	}
	return(err);
}

int
echo_open(dev_t dev, int oflags, int devtype, struct proc *p)
{
	int err = 0;

	uprintf("Opened device \"echo\" successfully.\n");
	return(err);
}

int
echo_close(dev_t dev, int fflag, int devtype, struct proc *p)
{
	uprintf("Closing device \"echo.\"\n");
	return(0);
}

/*
 * readº¯Êý½ÓÊÜÓÉecho_write()´æ´¢µÄbuf£¬²¢½«Æä·µ»Øµ½Óû§¿Õ¼ä£¬
 * ÒÔ¹©ÆäËûº¯Êý·ÃÎÊ¡£
 * uio(9)
 */

int
echo_read(dev_t dev, struct uio *uio, int ioflag)
{
	int err = 0;
	int amt;

	/*
	 * Õâ¸ö¶Á²Ù×÷Óжà´ó£¿
	 * ÓëÓû§ÇëÇóµÄ´óСһÑù£¬»òÕßµÈÓÚÊ£ÓàÊý¾ÝµÄ´óС¡£
	 */
	amt = MIN(uio->uio_resid, (echomsg->len - uio->uio_offset > 0) ?
	    echomsg->len - uio->uio_offset : 0);
	if ((err = uiomove(echomsg->msg + uio->uio_offset,amt,uio)) != 0) {
		uprintf("uiomove failed!\n");
	}
	return(err);
}

/*
 * echo_write½ÓÊÜÒ»¸ö×Ö·û´®²¢½«Ëü±£´æµ½»º³åÇø£¬ÓÃÓÚÒÔºóµÄ·ÃÎÊ¡£
 */

int
echo_write(dev_t dev, struct uio *uio, int ioflag)
{
	int err = 0;

	/* ½«×Ö·û´®´ÓÓû§¿Õ¼äµÄÄÚ´æ¸´ÖÆµ½Äں˿ռä */
	err = copyin(uio->uio_iov->iov_base, echomsg->msg,
	    MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1));

	/* ÏÖÔÚÐèÒªÒÔnull½áÊø×Ö·û´®£¬²¢¼Ç¼³¤¶È */
	*(echomsg->msg + MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1)) = 0;
	echomsg->len = MIN(uio->uio_iov->iov_len, BUFFERSIZE);

	if (err != 0) {
		uprintf("Write failed: bad address!\n");
	}
	count++;
	return(err);
}

DEV_MODULE(echo,echo_loader,NULL);

Àý 9-2. ÊÊÓÃÓÚFreeBSD 5.X»ØÏÔαÉ豸Çý¶¯³ÌÐòʵÀý

/*
 * ¼òµ¥¡®echo¡¯Î±É豸 KLD
 *
 * Murray Stokely
 *
 * ´Ë´úÂëÓÉSøren (Xride) Straarupת»»µ½5.X
 */

#include <sys/types.h>
#include <sys/module.h>
#include <sys/systm.h>  /* uprintf */
#include <sys/errno.h>
#include <sys/param.h>  /* kernel.hÖÐÓõ½µÄ¶¨Òå */
#include <sys/kernel.h> /* Ä£¿é³õʼ»¯ÖÐʹÓõÄÀàÐÍ */
#include <sys/conf.h>   /* cdevsw½á¹¹ */
#include <sys/uio.h>    /* uio½á¹¹ */
#include <sys/malloc.h>

#define BUFFERSIZE 256


/* º¯ÊýÔ­ÐÍ */
static d_open_t      echo_open;
static d_close_t     echo_close;
static d_read_t      echo_read;
static d_write_t     echo_write;

/* ×Ö·ûÉ豸Èë¿Úµã */
static struct cdevsw echo_cdevsw = {
	.d_version = D_VERSION,
	.d_open = echo_open,
	.d_close = echo_close,
	.d_read = echo_read,
	.d_write = echo_write,
	.d_name = "echo",
};

typedef struct s_echo {
	char msg[BUFFERSIZE];
	int len;
} t_echo;

/* ±äÁ¿ */
static struct cdev *echo_dev;
static int count;
static t_echo *echomsg;

MALLOC_DECLARE(M_ECHOBUF);
MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");

/*
 * Õâ¸öº¯Êý±»kld[un]load(2)ϵͳµ÷ÓÃÀ´µ÷ÓÃ, 
 * ÒÔ¾ö¶¨¼ÓÔØºÍÐ¶ÔØÄ£¿éʱÐèÒª²ÉÈ¡µÄ¶¯×÷. 
 */

static int
echo_loader(struct module *m, int what, void *arg)
{
	int err = 0;

	switch (what) {
	case MOD_LOAD:                /* kldload */
		echo_dev = make_dev(&echo_cdevsw,
		    0,
		    UID_ROOT,
		    GID_WHEEL,
		    0600,
		    "echo");
		/* kmalloc·ÖÅ乩Çý¶¯³ÌÐòʹÓõÄÄÚ´æ */
		echomsg = malloc(sizeof(t_echo), M_ECHOBUF, M_WAITOK);
		printf("Echo device loaded.\n");
		break;
	case MOD_UNLOAD:
		destroy_dev(echo_dev);
		free(echomsg, M_ECHOBUF);
		printf("Echo device unloaded.\n");
		break;
	default:
		err = EOPNOTSUPP;
		break;
	}
	return(err);
}

static int
echo_open(struct cdev *dev, int oflags, int devtype, struct thread *p)
{
	int err = 0;

	uprintf("Opened device \"echo\" successfully.\n");
	return(err);
}

static int
echo_close(struct cdev *dev, int fflag, int devtype, struct thread *p)
{
	uprintf("Closing device \"echo.\"\n");
	return(0);
}

/*
 * readº¯Êý½ÓÊÜÓÉecho_write()´æ´¢µÄbuf£¬²¢½«Æä·µ»Øµ½Óû§¿Õ¼ä£¬
 * ÒÔ¹©ÆäËûº¯Êý·ÃÎÊ¡£
 * uio(9)
 */

static int
echo_read(struct cdev *dev, struct uio *uio, int ioflag)
{
	int err = 0;
	int amt;

	/*
	 * Õâ¸ö¶Á²Ù×÷Óжà´ó£¿
	 * µÈÓÚÓû§ÇëÇóµÄ´óС£¬»òÕßµÈÓÚÊ£ÓàÊý¾ÝµÄ´óС¡£
	 */
	amt = MIN(uio->uio_resid, (echomsg->len - uio->uio_offset > 0) ?
	     echomsg->len - uio->uio_offset : 0);
	if ((err = uiomove(echomsg->msg + uio->uio_offset, amt, uio)) != 0) {
		uprintf("uiomove failed!\n");
	}
	return(err);
}

/*
 * echo_write½ÓÊÜÒ»¸ö×Ö·û´®²¢½«Ëü±£´æµ½»º³åÇø, ÓÃÓÚÒÔºóµÄ·ÃÎÊ. 
 */

static int
echo_write(struct cdev *dev, struct uio *uio, int ioflag)
{
	int err = 0;

	/* ½«×Ö·û´®´ÓÓû§¿Õ¼äµÄÄÚ´æ¸´ÖÆµ½Äں˿ռä */
	err = copyin(uio->uio_iov->iov_base, echomsg->msg,
	    MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1));

	/* ÏÖÔÚÐèÒªÒÔnull½áÊø×Ö·û´®£¬²¢¼Ç¼³¤¶È */
	*(echomsg->msg + MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1)) = 0;
	echomsg->len = MIN(uio->uio_iov->iov_len, BUFFERSIZE);

	if (err != 0) {
		uprintf("Write failed: bad address!\n");
	}
	count++;
	return(err);
}

DEV_MODULE(echo,echo_loader,NULL);

¡¡¡¡ÔÚFreeBSD 4.XÉϰ²×°´ËÇý¶¯³ÌÐò£¬Ä㽫Ê×ÏÈÐèÒªÓÃÈçÏÂÃüÁîÔÚ ÄãµÄÎļþϵͳÉÏ´´½¨Ò»¸ö½Úµã£º

# mknod /dev/echo c 33 0

¡¡¡¡Çý¶¯³ÌÐò±»¼ÓÔØºó£¬ÄãÓ¦¸ÃÄܹ»¼üÈëһЩ¶«Î÷£¬È磺

# echo -n "Test Data" > /dev/echo
# cat /dev/echo
Test Data

¡¡¡¡ÕæÕýµÄÓ²¼þÉ豸ÔÚÏÂÒ»ÕÂÃèÊö¡£

¡¡¡¡²¹³ä×ÊÔ´

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