1 /* $NetBSD: cnmagic.c,v 1.2 2000/12/19 04:39:19 mrg 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/param.h> 34 #include <sys/systm.h> 35 #include <sys/kernel.h> 36 37 #define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9)) 38 39 static unsigned short cn_magic[CNS_LEN]; 40 41 /* 42 * Initialize a cnm_state_t. 43 */ 44 void 45 cn_init_magic(cnm_state_t *cnm) { 46 cnm->cnm_state = 0; 47 cnm->cnm_magic = cn_magic; 48 } 49 50 /* 51 * Destroy a cnm_state_t. 52 */ 53 void 54 cn_destroy_magic(cnm_state_t *cnm) { 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(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, int maglen) { 123 unsigned int i, c; 124 125 for (i=0; i<CNS_LEN; i++) { 126 c = cn_magic[i]; 127 /* Translate a character */ 128 switch (CNS_MAGIC_VAL(c)) { 129 case CNC_BREAK: 130 *magic++ = 0x27; 131 *magic++ = 0x01; 132 break; 133 case 0: 134 *magic++ = 0x27; 135 *magic++ = 0x02; 136 break; 137 case 0x27: 138 *magic++ = 0x27; 139 *magic++ = 0x27; 140 break; 141 default: 142 *magic++ = (c&0x0ff); 143 break; 144 } 145 /* Now go to the next state */ 146 i = CNS_MAGIC_NEXT(c); 147 if (i == CNS_TERM || i == 0) { 148 /* Either termination state or empty machine */ 149 *magic++ = 0; 150 return (0); 151 } 152 } 153 return (EINVAL); 154 } 155 156