NetBSD/sys/kern/cnmagic.c

170 lines
3.6 KiB
C

/* $NetBSD: cnmagic.c,v 1.13 2011/11/19 17:34:41 christos Exp $ */
/*
* Copyright (c) 2000 Eduardo Horvath
* All rights reserved.
*
* 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 AUTHOR ``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 AUTHOR 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>
__KERNEL_RCSID(0, "$NetBSD: cnmagic.c,v 1.13 2011/11/19 17:34:41 christos Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9))
static unsigned short cn_magic[CNS_LEN];
/*
* Initialize a cnm_state_t.
*/
void
cn_init_magic(cnm_state_t *cnm)
{
cnm->cnm_state = 0;
cnm->cnm_magic = cn_magic;
}
/*
* Destroy a cnm_state_t.
*/
void
cn_destroy_magic(cnm_state_t *cnm)
{
cnm->cnm_state = 0;
cnm->cnm_magic = NULL;
}
/*
* Translate a magic string to a state
* machine table.
*/
int
cn_set_magic(const char *smagic)
{
const unsigned char *magic = (const unsigned char *)smagic;
unsigned short i, c, n;
unsigned short m[CNS_LEN];
for (i = 0; i < CNS_LEN; i++) {
c = *magic++;
switch (c) {
case 0:
/* End of string */
if (i == 0) {
/* empty string? */
#ifdef DEBUG
printf("cn_set_magic(): empty!\n");
#endif
}
cn_magic[i] = 0;
while (i--)
cn_magic[i] = m[i];
return 0;
case 0x27:
/* Escape sequence */
c = *magic++;
switch (c) {
case 0x27:
break;
case 0x01:
/* BREAK */
c = CNC_BREAK;
break;
case 0x02:
/* NUL */
c = 0;
break;
}
/* FALLTHROUGH */
default:
/* Transition to the next state. */
n = *magic ? i + 1 : CNS_TERM;
#ifdef DEBUG
if (!cold)
aprint_normal("mag %d %x:%x\n", i, c, n);
#endif
m[i] = ENCODE_STATE(c, n);
break;
}
}
return EINVAL;
}
/*
* Translatea state machine table back to
* a magic string.
*/
int
cn_get_magic(char *magic, size_t maglen)
{
size_t i, n = 0;
#define ADD_CHAR(x) \
do \
if (n < maglen) \
magic[n++] = (x); \
else \
goto error; \
while (/*CONSTCOND*/0)
for (i = 0; i < CNS_LEN; /* empty */) {
unsigned short c = cn_magic[i];
i = CNS_MAGIC_NEXT(c);
if (i == 0)
goto finish;
/* Translate a character */
switch (CNS_MAGIC_VAL(c)) {
case CNC_BREAK:
ADD_CHAR(0x27);
ADD_CHAR(0x01);
break;
case 0:
ADD_CHAR(0x27);
ADD_CHAR(0x02);
break;
case 0x27:
ADD_CHAR(0x27);
ADD_CHAR(0x27);
break;
default:
ADD_CHAR(c);
break;
}
/* Now go to the next state */
if (i == CNS_TERM)
goto finish;
}
error:
return EINVAL;
finish:
/* Either termination state or empty machine */
ADD_CHAR('\0');
return 0;
}