sys/kern/cnmagic.c

   1 /*      $NetBSD: cnmagic.c,v 1.9 2006/11/01 10:17:58 yamt 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  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 __KERNEL_RCSID(0, "$NetBSD: cnmagic.c,v 1.9 2006/11/01 10:17:58 yamt Exp $");
  30
  31 #include <sys/param.h>
  32 #include <sys/systm.h>
  33 #include <sys/kernel.h>
  34
  35 #define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9))
  36
  37 static unsigned short cn_magic[CNS_LEN];
  38
  39 /*
  40  * Initialize a cnm_state_t.
  41  */
  42 void
  43 cn_init_magic(cnm_state_t *cnm)
  44 {
  45         cnm->cnm_state = 0;
  46         cnm->cnm_magic = cn_magic;
  47 }
  48
  49 /*
  50  * Destroy a cnm_state_t.
  51  */
  52 void
  53 cn_destroy_magic(cnm_state_t *cnm)
  54 {
  55         cnm->cnm_state = 0;
  56         cnm->cnm_magic = NULL;
  57 }
  58
  59 /*
  60  * Translate a magic string to a state
  61  * machine table.
  62  */
  63 int
  64 cn_set_magic(const char *magic)
  65 {
  66         unsigned int i, c, n;
  67         unsigned short m[CNS_LEN];
  68
  69         for (i = 0; i < CNS_LEN; i++) {
  70                 c = (*magic++) & 0xff;
  71                 n = *magic ? i+1 : CNS_TERM;
  72                 switch (c) {
  73                 case 0:
  74                         /* End of string */
  75                         if (i == 0) {
  76                                 /* empty string? */
  77                                 cn_magic[0] = 0;
  78 #ifdef DEBUG
  79                                 printf("cn_set_magic(): empty!\n");
  80 #endif
  81                                 return (0);
  82                         }
  83                         do {
  84                                 cn_magic[i] = m[i];
  85                         } while (i--);
  86                         return(0);
  87                 case 0x27:
  88                         /* Escape sequence */
  89                         c = (*magic++) & 0xff;
  90                         n = *magic ? i+1 : CNS_TERM;
  91                         switch (c) {
  92                         case 0x27:
  93                                 break;
  94                         case 0x01:
  95                                 /* BREAK */
  96                                 c = CNC_BREAK;
  97                                 break;
  98                         case 0x02:
  99                                 /* NUL */
 100                                 c = 0;
 101                                 break;
 102                         }
 103                         /* FALLTHROUGH */
 104                 default:
 105                         /* Transition to the next state. */
 106 #ifdef DEBUG
 107                         if (!cold)
 108                                 printf("mag %d %x:%x\n", i, c, n);
 109 #endif
 110                         m[i] = ENCODE_STATE(c, n);
 111                         break;
 112                 }
 113         }
 114         return (EINVAL);
 115 }
 116
 117 /*
 118  * Translatea state machine table back to
 119  * a magic string.
 120  */
 121 int
 122 cn_get_magic(char *magic, size_t maglen)
 123 {
 124         size_t i, c;
 125
 126         for (i = 0; i < CNS_LEN;) {
 127                 c = cn_magic[i];
 128                 /* Translate a character */
 129                 switch (CNS_MAGIC_VAL(c)) {
 130                 case CNC_BREAK:
 131                         *magic++ = 0x27;
 132                         *magic++ = 0x01;
 133                         break;
 134                 case 0:
 135                         *magic++ = 0x27;
 136                         *magic++ = 0x02;
 137                         break;
 138                 case 0x27:
 139                         *magic++ = 0x27;
 140                         *magic++ = 0x27;
 141                         break;
 142                 default:
 143                         *magic++ = (c & 0x0ff);
 144                         break;
 145                 }
 146                 /* Now go to the next state */
 147                 i = CNS_MAGIC_NEXT(c);
 148                 if (i == CNS_TERM || i == 0) {
 149                         /* Either termination state or empty machine */
 150                         *magic++ = 0;
 151                         return (0);
 152                 }
 153         }
 154         return (EINVAL);
 155 }
 156