1/* $NetBSD: cnmagic.c,v 1.14 2017/05/04 11:01:16 kamil 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 1.14 2017/05/04 11:01:16 kamil 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 37static unsigned short cn_magic[CNS_LEN]; 38 39/* 40 * Initialize a cnm_state_t. 41 */ 42void 43cn_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 */ 52void 53cn_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 */ 63int 64cn_set_magic(const char *smagic) 65{ 66 const unsigned char *magic = (const unsigned char *)smagic; 67 unsigned short i, c, n; 68 unsigned short m[CNS_LEN]; 69 70 for (i = 0; i < CNS_LEN; i++) { 71 c = *magic++; 72 switch (c) { 73 case 0: 74 /* End of string */ 75 if (i == 0) { 76 /* empty string? */ 77#ifdef DEBUG 78 printf("cn_set_magic(): empty!\n"); 79#endif 80 } 81 cn_magic[i] = 0; 82 while (i--) 83 cn_magic[i] = m[i]; 84 return 0; 85 case 0x27: 86 /* Escape sequence */ 87 c = *magic++; 88 switch (c) { 89 case 0x27: 90 break; 91 case 0x01: 92 /* BREAK */ 93 c = CNC_BREAK; 94 break; 95 case 0x02: 96 /* NUL */ 97 c = 0; 98 break; 99 } 100 /* FALLTHROUGH */ 101 default: 102 /* Transition to the next state. */ 103 n = *magic ? i + 1 : CNS_TERM; 104#ifdef DEBUG 105 if (!cold) 106 aprint_normal("mag %d %x:%x\n", i, c, n); 107#endif 108 m[i] = ENCODE_STATE(c, n); 109 break; 110 } 111 } 112 return EINVAL; 113} 114 115/* 116 * Translate a state machine table back to 117 * a magic string. 118 */ 119int 120cn_get_magic(char *magic, size_t maglen) 121{ 122 size_t i, n = 0; 123 124#define ADD_CHAR(x) \ 125do \ 126 if (n < maglen) \ 127 magic[n++] = (x); \ 128 else \ 129 goto error; \ 130while (/*CONSTCOND*/0) 131 132 for (i = 0; i < CNS_LEN; /* empty */) { 133 unsigned short c = cn_magic[i]; 134 i = CNS_MAGIC_NEXT(c); 135 if (i == 0) 136 goto finish; 137 138 /* Translate a character */ 139 switch (CNS_MAGIC_VAL(c)) { 140 case CNC_BREAK: 141 ADD_CHAR(0x27); 142 ADD_CHAR(0x01); 143 break; 144 case 0: 145 ADD_CHAR(0x27); 146 ADD_CHAR(0x02); 147 break; 148 case 0x27: 149 ADD_CHAR(0x27); 150 ADD_CHAR(0x27); 151 break; 152 default: 153 ADD_CHAR(c); 154 break; 155 } 156 /* Now go to the next state */ 157 if (i == CNS_TERM) 158 goto finish; 159 } 160 161error: 162 return EINVAL; 163 164finish: 165 /* Either termination state or empty machine */ 166 ADD_CHAR('\0'); 167 return 0; 168} 169