parameters.c

linux 内核源代码

/*********************************************************************
 *
 * Filename:      parameters.c
 * Version:       1.0
 * Description:   A more general way to handle (pi,pl,pv) parameters
 * Status:        Experimental.
 * Author:        Dag Brattli <[e-mail]>
 * Created at:    Mon Jun  7 10:25:11 1999
 * Modified at:   Sun Jan 30 14:08:39 2000
 * Modified by:   Dag Brattli <[e-mail]>
 *
 *     Copyright (c) 1999-2000 Dag Brattli, All Rights Reserved.
 *
 *     This program is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of
 *     the License, or (at your option) any later version.
 *
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program; if not, write to the Free Software
 *     Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *     MA 02111-1307 USA
 *
 ********************************************************************/

#include <linux/types.h>
#include <linux/module.h>

#include <asm/unaligned.h>
#include <asm/byteorder.h>

#include <net/irda/irda.h>
#include <net/irda/parameters.h>

static int irda_extract_integer(void *self, __u8 *buf, int len, __u8 pi,
				PV_TYPE type, PI_HANDLER func);
static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
			       PV_TYPE type, PI_HANDLER func);
static int irda_extract_octseq(void *self, __u8 *buf, int len, __u8 pi,
			       PV_TYPE type, PI_HANDLER func);
static int irda_extract_no_value(void *self, __u8 *buf, int len, __u8 pi,
				 PV_TYPE type, PI_HANDLER func);

static int irda_insert_integer(void *self, __u8 *buf, int len, __u8 pi,
			       PV_TYPE type, PI_HANDLER func);
static int irda_insert_no_value(void *self, __u8 *buf, int len, __u8 pi,
				PV_TYPE type, PI_HANDLER func);

static int irda_param_unpack(__u8 *buf, char *fmt, ...);

/* Parameter value call table. Must match PV_TYPE */
static PV_HANDLER pv_extract_table[] = {
	irda_extract_integer, /* Handler for any length integers */
	irda_extract_integer, /* Handler for 8  bits integers */
	irda_extract_integer, /* Handler for 16 bits integers */
	irda_extract_string,  /* Handler for strings */
	irda_extract_integer, /* Handler for 32 bits integers */
	irda_extract_octseq,  /* Handler for octet sequences */
	irda_extract_no_value /* Handler for no value parameters */
};

static PV_HANDLER pv_insert_table[] = {
	irda_insert_integer, /* Handler for any length integers */
	irda_insert_integer, /* Handler for 8  bits integers */
	irda_insert_integer, /* Handler for 16 bits integers */
	NULL,                /* Handler for strings */
	irda_insert_integer, /* Handler for 32 bits integers */
	NULL,                /* Handler for octet sequences */
	irda_insert_no_value /* Handler for no value parameters */
};

/*
 * Function irda_insert_no_value (self, buf, len, pi, type, func)
 */
static int irda_insert_no_value(void *self, __u8 *buf, int len, __u8 pi,
				PV_TYPE type, PI_HANDLER func)
{
	irda_param_t p;
	int ret;

	p.pi = pi;
	p.pl = 0;

	/* Call handler for this parameter */
	ret = (*func)(self, &p, PV_GET);

	/* Extract values anyway, since handler may need them */
	irda_param_pack(buf, "bb", p.pi, p.pl);

	if (ret < 0)
		return ret;

	return 2; /* Inserted pl+2 bytes */
}

/*
 * Function irda_extract_no_value (self, buf, len, type, func)
 *
 *    Extracts a parameter without a pv field (pl=0)
 *
 */
static int irda_extract_no_value(void *self, __u8 *buf, int len, __u8 pi,
				 PV_TYPE type, PI_HANDLER func)
{
	irda_param_t p;
	int ret;

	/* Extract values anyway, since handler may need them */
	irda_param_unpack(buf, "bb", &p.pi, &p.pl);

	/* Call handler for this parameter */
	ret = (*func)(self, &p, PV_PUT);

	if (ret < 0)
		return ret;

	return 2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_insert_integer (self, buf, len, pi, type, func)
 */
static int irda_insert_integer(void *self, __u8 *buf, int len, __u8 pi,
			       PV_TYPE type, PI_HANDLER func)
{
	irda_param_t p;
	int n = 0;
	int err;

	p.pi = pi;             /* In case handler needs to know */
	p.pl = type & PV_MASK; /* The integer type codes the length as well */
	p.pv.i = 0;            /* Clear value */

	/* Call handler for this parameter */
	err = (*func)(self, &p, PV_GET);
	if (err < 0)
		return err;

	/*
	 * If parameter length is still 0, then (1) this is an any length
	 * integer, and (2) the handler function does not care which length
	 * we choose to use, so we pick the one the gives the fewest bytes.
	 */
	if (p.pl == 0) {
		if (p.pv.i < 0xff) {
			IRDA_DEBUG(2, "%s(), using 1 byte\n", __FUNCTION__);
			p.pl = 1;
		} else if (p.pv.i < 0xffff) {
			IRDA_DEBUG(2, "%s(), using 2 bytes\n", __FUNCTION__);
			p.pl = 2;
		} else {
			IRDA_DEBUG(2, "%s(), using 4 bytes\n", __FUNCTION__);
			p.pl = 4; /* Default length */
		}
	}
	/* Check if buffer is long enough for insertion */
	if (len < (2+p.pl)) {
		IRDA_WARNING("%s: buffer too short for insertion!\n",
			     __FUNCTION__);
		return -1;
	}
	IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d, pi=%d\n", __FUNCTION__,
		   p.pi, p.pl, p.pv.i);
	switch (p.pl) {
	case 1:
		n += irda_param_pack(buf, "bbb", p.pi, p.pl, (__u8) p.pv.i);
		break;
	case 2:
		if (type & PV_BIG_ENDIAN)
			p.pv.i = cpu_to_be16((__u16) p.pv.i);
		else
			p.pv.i = cpu_to_le16((__u16) p.pv.i);
		n += irda_param_pack(buf, "bbs", p.pi, p.pl, (__u16) p.pv.i);
		break;
	case 4:
		if (type & PV_BIG_ENDIAN)
			cpu_to_be32s(&p.pv.i);
		else
			cpu_to_le32s(&p.pv.i);
		n += irda_param_pack(buf, "bbi", p.pi, p.pl, p.pv.i);

		break;
	default:
		IRDA_WARNING("%s: length %d not supported\n",
			     __FUNCTION__, p.pl);
		/* Skip parameter */
		return -1;
	}

	return p.pl+2; /* Inserted pl+2 bytes */
}

/*
 * Function irda_extract integer (self, buf, len, pi, type, func)
 *
 *    Extract a possibly variable length integer from buffer, and call
 *    handler for processing of the parameter
 */
static int irda_extract_integer(void *self, __u8 *buf, int len, __u8 pi,
				PV_TYPE type, PI_HANDLER func)
{
	irda_param_t p;
	int n = 0;
	int extract_len;	/* Real length we extract */
	int err;

	p.pi = pi;     /* In case handler needs to know */
	p.pl = buf[1]; /* Extract length of value */
	p.pv.i = 0;    /* Clear value */
	extract_len = p.pl;	/* Default : extract all */

	/* Check if buffer is long enough for parsing */
	if (len < (2+p.pl)) {
		IRDA_WARNING("%s: buffer too short for parsing! "
			     "Need %d bytes, but len is only %d\n",
			     __FUNCTION__, p.pl, len);
		return -1;
	}

	/*
	 * Check that the integer length is what we expect it to be. If the
	 * handler want a 16 bits integer then a 32 bits is not good enough
	 * PV_INTEGER means that the handler is flexible.
	 */
	if (((type & PV_MASK) != PV_INTEGER) && ((type & PV_MASK) != p.pl)) {
		IRDA_ERROR("%s: invalid parameter length! "
			   "Expected %d bytes, but value had %d bytes!\n",
			   __FUNCTION__, type & PV_MASK, p.pl);

		/* Most parameters are bit/byte fields or little endian,
		 * so it's ok to only extract a subset of it (the subset
		 * that the handler expect). This is necessary, as some
		 * broken implementations seems to add extra undefined bits.
		 * If the parameter is shorter than we expect or is big
		 * endian, we can't play those tricks. Jean II */
		if((p.pl < (type & PV_MASK)) || (type & PV_BIG_ENDIAN)) {
			/* Skip parameter */
			return p.pl+2;
		} else {
			/* Extract subset of it, fallthrough */
			extract_len = type & PV_MASK;
		}
	}


	switch (extract_len) {
	case 1:
		n += irda_param_unpack(buf+2, "b", &p.pv.i);
		break;
	case 2:
		n += irda_param_unpack(buf+2, "s", &p.pv.i);
		if (type & PV_BIG_ENDIAN)
			p.pv.i = be16_to_cpu((__u16) p.pv.i);
		else
			p.pv.i = le16_to_cpu((__u16) p.pv.i);
		break;
	case 4:
		n += irda_param_unpack(buf+2, "i", &p.pv.i);
		if (type & PV_BIG_ENDIAN)
			be32_to_cpus(&p.pv.i);
		else
			le32_to_cpus(&p.pv.i);
		break;
	default:
		IRDA_WARNING("%s: length %d not supported\n",
			     __FUNCTION__, p.pl);

		/* Skip parameter */
		return p.pl+2;
	}

	IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d, pi=%d\n", __FUNCTION__,
		   p.pi, p.pl, p.pv.i);
	/* Call handler for this parameter */
	err = (*func)(self, &p, PV_PUT);
	if (err < 0)
		return err;

	return p.pl+2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_extract_string (self, buf, len, type, func)
 */
static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
			       PV_TYPE type, PI_HANDLER func)
{
	char str[33];
	irda_param_t p;
	int err;