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cnmagic.c revision 1.3 
      1 /*	$NetBSD: cnmagic.c,v 1.3 2001/11/12 15:25:01 lukem Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2000 Eduardo Horvath
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *      This product includes software developed by Eduardo Horvath.
     18  * 4. The name of the author may not be used to endorse or promote products
     19  *    derived from this software without specific prior written permission
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 __KERNEL_RCSID(0, "$NetBSD: cnmagic.c,v 1.3 2001/11/12 15:25:01 lukem Exp $");
     35 
     36 #include <sys/param.h>
     37 #include <sys/systm.h>
     38 #include <sys/kernel.h>
     39 
     40 #define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9))
     41 
     42 static unsigned short cn_magic[CNS_LEN];
     43 
     44 /*
     45  * Initialize a cnm_state_t.
     46  */
     47 void
     48 cn_init_magic(cnm_state_t *cnm) {
     49 	cnm->cnm_state = 0;
     50 	cnm->cnm_magic = cn_magic;
     51 }
     52 
     53 /*
     54  * Destroy a cnm_state_t.
     55  */
     56 void
     57 cn_destroy_magic(cnm_state_t *cnm) {
     58 	cnm->cnm_state = 0;
     59 	cnm->cnm_magic = NULL;
     60 }
     61 
     62 /*
     63  * Translate a magic string to a state
     64  * machine table.
     65  */
     66 int
     67 cn_set_magic(char *magic)
     68 {
     69 	unsigned int i, c, n;
     70 	unsigned short m[CNS_LEN];
     71 
     72 	for (i=0; i<CNS_LEN; i++) {
     73 		c = (*magic++)&0xff;
     74 		n = *magic ? i+1 : CNS_TERM;
     75 		switch (c) {
     76 		case 0:
     77 			/* End of string */
     78 			if (i == 0) {
     79 				/* empty string? */
     80 				cn_magic[0] = 0;
     81 #ifdef DEBUG
     82 				printf("cn_set_magic(): empty!\n");
     83 #endif
     84 				return (0);
     85 			}
     86 			do {
     87 				cn_magic[i] = m[i];
     88 			} while (i--);
     89 			return(0);
     90 		case 0x27:
     91 			/* Escape sequence */
     92 			c = (*magic++)&0xff;
     93 			n = *magic ? i+1 : CNS_TERM;
     94 			switch (c) {
     95 			case 0x27:
     96 				break;
     97 			case 0x01:
     98 				/* BREAK */
     99 				c = CNC_BREAK;
    100 				break;
    101 			case 0x02:
    102 				/* NUL */
    103 				c = 0;
    104 				break;
    105 			}
    106 			/* FALLTHROUGH */
    107 		default:
    108 			/* Transition to the next state. */
    109 #ifdef DEBUG
    110 			if (!cold)
    111 				printf("mag %d %x:%x\n", i, c, n);
    112 #endif
    113 			m[i] = ENCODE_STATE(c, n);
    114 			break;
    115 		}
    116 	}
    117 	return (EINVAL);
    118 }
    119 
    120 /*
    121  * Translatea state machine table back to
    122  * a magic string.
    123  */
    124 int
    125 cn_get_magic(char *magic, int maglen) {
    126 	unsigned int i, c;
    127 
    128 	for (i=0; i<CNS_LEN; i++) {
    129 		c = cn_magic[i];
    130 		/* Translate a character */
    131 		switch (CNS_MAGIC_VAL(c)) {
    132 		case CNC_BREAK:
    133 			*magic++ = 0x27;
    134 			*magic++ = 0x01;
    135 			break;
    136 		case 0:
    137 			*magic++ = 0x27;
    138 			*magic++ = 0x02;
    139 			break;
    140 		case 0x27:
    141 			*magic++ = 0x27;
    142 			*magic++ = 0x27;
    143 			break;
    144 		default:
    145 			*magic++ = (c&0x0ff);
    146 			break;
    147 		}
    148 		/* Now go to the next state */
    149 		i = CNS_MAGIC_NEXT(c);
    150 		if (i == CNS_TERM || i == 0) {
    151 			/* Either termination state or empty machine */
    152 			*magic++ = 0;
    153 			return (0);
    154 		}
    155 	}
    156 	return (EINVAL);
    157 }
    158 
    159