1 /* $NetBSD: bm.c,v 1.13 2014/06/23 10:43:25 shm 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
38 static char sccsid[] = "@(#)bm.c 8.7 (Berkeley) 6/21/94";
39 #else
40 __RCSID("$NetBSD: bm.c,v 1.13 2014/06/23 10:43:25 shm 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 */
67 static 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
102 bm_pat *
bm_comp(u_char const * pb,size_t len,u_char const * freq)103 bm_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
153 mem: sv_errno = errno;
154 bm_free(pat);
155 errno = sv_errno;
156 return (NULL);
157 }
158
159 void
bm_free(bm_pat * pat)160 bm_free(bm_pat *pat)
161 {
162
163 _DIAGASSERT(pat != NULL);
164
165 free(pat->pat);
166 free(pat->delta);
167 free(pat);
168 }
169
170 u_char *
bm_exec(bm_pat * pat,u_char * base,size_t n)171 bm_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
209 mismatch1: 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
226 mismatch2: s += md2; /* md2 shift */
227 }
228
229 return (NULL);
230 }
231