NetBSD/sys/kern/cnmagic.c

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/* $NetBSD: cnmagic.c,v 1.9 2006/11/01 10:17:58 yamt Exp $ */
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/*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Eduardo Horvath.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* 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.
*/
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#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: cnmagic.c,v 1.9 2006/11/01 10:17:58 yamt Exp $");
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#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
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#define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9))
static unsigned short cn_magic[CNS_LEN];
/*
* Initialize a cnm_state_t.
*/
void
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cn_init_magic(cnm_state_t *cnm)
{
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cnm->cnm_state = 0;
cnm->cnm_magic = cn_magic;
}
/*
* Destroy a cnm_state_t.
*/
void
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cn_destroy_magic(cnm_state_t *cnm)
{
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cnm->cnm_state = 0;
cnm->cnm_magic = NULL;
}
/*
* Translate a magic string to a state
* machine table.
*/
int
cn_set_magic(const char *magic)
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{
unsigned int i, c, n;
unsigned short m[CNS_LEN];
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for (i = 0; i < CNS_LEN; i++) {
c = (*magic++) & 0xff;
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n = *magic ? i+1 : CNS_TERM;
switch (c) {
case 0:
/* End of string */
if (i == 0) {
/* empty string? */
cn_magic[0] = 0;
#ifdef DEBUG
printf("cn_set_magic(): empty!\n");
#endif
return (0);
}
do {
cn_magic[i] = m[i];
} while (i--);
return(0);
case 0x27:
/* Escape sequence */
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c = (*magic++) & 0xff;
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n = *magic ? i+1 : CNS_TERM;
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. */
#ifdef DEBUG
if (!cold)
printf("mag %d %x:%x\n", i, c, n);
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#endif
m[i] = ENCODE_STATE(c, n);
break;
}
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}
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return (EINVAL);
}
/*
* Translatea state machine table back to
* a magic string.
*/
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int
cn_get_magic(char *magic, size_t maglen)
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{
size_t i, c;
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for (i = 0; i < CNS_LEN;) {
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c = cn_magic[i];
/* Translate a character */
switch (CNS_MAGIC_VAL(c)) {
case CNC_BREAK:
*magic++ = 0x27;
*magic++ = 0x01;
break;
case 0:
*magic++ = 0x27;
*magic++ = 0x02;
break;
case 0x27:
*magic++ = 0x27;
*magic++ = 0x27;
break;
default:
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*magic++ = (c & 0x0ff);
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break;
}
/* Now go to the next state */
i = CNS_MAGIC_NEXT(c);
if (i == CNS_TERM || i == 0) {
/* Either termination state or empty machine */
*magic++ = 0;
return (0);
}
}
return (EINVAL);
}