1/* $NetBSD: bm.c,v 1.12 2012/06/25 22:32:46 abs Exp $ */ 2 3/*- 4 * Copyright (c) 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Andrew Hume of AT&T Bell Laboratories. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#include <sys/cdefs.h> 36#if defined(LIBC_SCCS) && !defined(lint) 37#if 0 38static char sccsid[] = "@(#)bm.c 8.7 (Berkeley) 6/21/94"; 39#else 40__RCSID("$NetBSD: bm.c,v 1.12 2012/06/25 22:32:46 abs Exp $"); 41#endif 42#endif /* LIBC_SCCS && not lint */ 43 44#include "namespace.h" 45#include <sys/types.h> 46 47#include <assert.h> 48#include <bm.h> 49#include <errno.h> 50#include <stdlib.h> 51#include <string.h> 52 53#ifdef __weak_alias 54__weak_alias(bm_comp,_bm_comp) 55__weak_alias(bm_exec,_bm_exec) 56__weak_alias(bm_free,_bm_free) 57#endif 58 59/* 60 * XXX 61 * The default frequency table starts at 99 and counts down. The default 62 * table should probably be oriented toward text, and will necessarily be 63 * locale specific. This one is for English. It was derived from the 64 * OSF/1 and 4.4BSD formatted and unformatted manual pages, and about 100Mb 65 * of email and random text. Change it if you can find something better. 66 */ 67static u_char const freq_def[256] = { 68 0, 0, 0, 0, 0, 0, 0, 0, 69 0, 77, 90, 0, 0, 0, 0, 0, 70 0, 0, 0, 0, 0, 0, 0, 0, 71 0, 0, 0, 0, 0, 0, 0, 0, 72 99, 28, 42, 27, 16, 14, 20, 51, 73 66, 65, 59, 24, 75, 76, 84, 56, 74 72, 74, 64, 55, 54, 47, 41, 37, 75 44, 61, 70, 43, 23, 53, 49, 22, 76 33, 58, 40, 46, 45, 57, 60, 26, 77 30, 63, 21, 12, 32, 50, 38, 39, 78 34, 11, 48, 67, 62, 35, 15, 29, 79 71, 18, 9, 17, 25, 13, 10, 52, 80 36, 95, 78, 86, 87, 98, 82, 80, 81 88, 94, 19, 68, 89, 83, 93, 96, 82 81, 7, 91, 92, 97, 85, 69, 73, 83 31, 79, 8, 5, 4, 6, 3, 0, 84 0, 0, 0, 0, 0, 0, 0, 0, 85 0, 0, 0, 0, 0, 0, 0, 0, 86 0, 0, 0, 0, 0, 0, 0, 0, 87 0, 0, 0, 0, 0, 0, 0, 0, 88 0, 0, 0, 0, 0, 0, 0, 0, 89 0, 0, 0, 0, 0, 0, 0, 0, 90 0, 0, 0, 0, 0, 0, 0, 0, 91 0, 0, 0, 0, 0, 0, 0, 0, 92 0, 0, 0, 0, 0, 0, 0, 0, 93 0, 0, 0, 0, 0, 0, 0, 0, 94 0, 0, 0, 0, 0, 0, 0, 0, 95 0, 0, 0, 0, 0, 0, 0, 0, 96 0, 0, 0, 0, 0, 0, 0, 0, 97 0, 0, 0, 0, 0, 0, 0, 0, 98 0, 0, 0, 0, 0, 0, 0, 0, 99 0, 0, 0, 0, 0, 0, 0, 0, 100}; 101 102bm_pat * 103bm_comp(u_char const *pb, size_t len, u_char const *freq) 104{ 105 u_char const *pe, *p; 106 size_t *d, r; 107 int j; 108 int sv_errno; 109 bm_pat *pat; 110 111 _DIAGASSERT(pb != NULL); 112 /* freq may be NULL */ 113 114 if (len == 0) { 115 errno = EINVAL; 116 return (NULL); 117 } 118 if ((pat = malloc(sizeof(*pat))) == NULL) 119 return (NULL); 120 pat->pat = NULL; 121 pat->delta = NULL; 122 123 pat->patlen = len; /* copy pattern */ 124 if ((pat->pat = malloc(pat->patlen)) == NULL) 125 goto mem; 126 memcpy(pat->pat, pb, pat->patlen); 127 /* get skip delta */ 128 if ((pat->delta = malloc(256 * sizeof(*d))) == NULL) 129 goto mem; 130 for (j = 0, d = pat->delta; j < 256; j++) 131 d[j] = pat->patlen; 132 for (pe = pb + pat->patlen - 1; pb <= pe; pb++) 133 d[*pb] = pe - pb; 134 135 if (freq == NULL) /* default freq table */ 136 freq = freq_def; 137 r = 0; /* get guard */ 138 for (pb = pat->pat, pe = pb + pat->patlen - 1; pb < pe; pb++) 139 if (freq[*pb] < freq[pat->pat[r]]) 140 r = pb - pat->pat; 141 pat->rarec = pat->pat[r]; 142 pat->rareoff = r - (pat->patlen - 1); 143 144 /* get md2 shift */ 145 for (pe = pat->pat + pat->patlen - 1, p = pe - 1; p >= pat->pat; p--) 146 if (*p == *pe) 147 break; 148 149 /* *p is first leftward reoccurrence of *pe */ 150 pat->md2 = pe - p; 151 return (pat); 152 153mem: sv_errno = errno; 154 bm_free(pat); 155 errno = sv_errno; 156 return (NULL); 157} 158 159void 160bm_free(bm_pat *pat) 161{ 162 163 _DIAGASSERT(pat != NULL); 164 165 free(pat->pat); 166 free(pat->delta); 167 free(pat); 168} 169 170u_char * 171bm_exec(bm_pat *pat, u_char *base, size_t n) 172{ 173 u_char *e, *ep, *p, *q, *s; 174 size_t *d0, k, md2, n1, ro; 175 int rc; 176 177 _DIAGASSERT(pat != NULL); 178 _DIAGASSERT(base != NULL); 179 180 if (n == 0) 181 return (NULL); 182 183 d0 = pat->delta; 184 n1 = pat->patlen - 1; 185 md2 = pat->md2; 186 ro = pat->rareoff; 187 rc = pat->rarec; 188 ep = pat->pat + pat->patlen - 1; 189 s = base + (pat->patlen - 1); 190 191 /* fast loop up to n - 3 * patlen */ 192 e = base + n - 3 * pat->patlen; 193 while (s < e) { 194 k = d0[*s]; /* ufast skip loop */ 195 while (k && s < e) { 196 k = d0[*(s += k)]; 197 k = d0[*(s += k)]; 198 } 199 if (s >= e) 200 break; 201 if (s[ro] != rc) /* guard test */ 202 goto mismatch1; 203 /* fwd match */ 204 for (p = pat->pat, q = s - n1; p < ep;) 205 if (*q++ != *p++) 206 goto mismatch1; 207 return (s - n1); 208 209mismatch1: s += md2; /* md2 shift */ 210 } 211 212 /* slow loop up to end */ 213 e = base + n; 214 while (s < e) { 215 s += d0[*s]; /* step */ 216 if (s >= e) 217 break; 218 if (s[ro] != rc) /* guard test */ 219 goto mismatch2; 220 /* fwd match */ 221 for (p = pat->pat, q = s - n1; p <= ep;) 222 if (*q++ != *p++) 223 goto mismatch2; 224 return (s - n1); 225 226mismatch2: s += md2; /* md2 shift */ 227 } 228 229 return (NULL); 230} 231