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/* $OpenBSD: bm.c,v 1.6 2005/08/08 08:05:37 espie Exp $ */
/*-
* Copyright (c) 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Andrew Hume of AT&T Bell Laboratories.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/types.h>
#include <bm.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
/*
* XXX
* The default frequency table starts at 99 and counts down. The default
* table should probably be oriented toward text, and will necessarily be
* locale specific. This one is for English. It was derived from the
* OSF/1 and 4.4BSD formatted and unformatted manual pages, and about 100Mb
* of email and random text. Change it if you can find something better.
*/
static u_char const freq_def[256] = {
0, 0, 0, 0, 0, 0, 0, 0,
0, 77, 90, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
99, 28, 42, 27, 16, 14, 20, 51,
66, 65, 59, 24, 75, 76, 84, 56,
72, 74, 64, 55, 54, 47, 41, 37,
44, 61, 70, 43, 23, 53, 49, 22,
33, 58, 40, 46, 45, 57, 60, 26,
30, 63, 21, 12, 32, 50, 38, 39,
34, 11, 48, 67, 62, 35, 15, 29,
71, 18, 9, 17, 25, 13, 10, 52,
36, 95, 78, 86, 87, 98, 82, 80,
88, 94, 19, 68, 89, 83, 93, 96,
81, 7, 91, 92, 97, 85, 69, 73,
31, 79, 8, 5, 4, 6, 3, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
};
bm_pat *
bm_comp(u_char const *pb, size_t len, u_char const *freq)
{
u_char const *pe, *p;
size_t *d, r;
int j;
int sv_errno;
bm_pat *pat;
if (len == 0) {
errno = EINVAL;
return (NULL);
}
if ((pat = malloc(sizeof(*pat))) == NULL)
return (NULL);
pat->pat = NULL;
pat->delta = NULL;
pat->patlen = len; /* copy pattern */
if ((pat->pat = malloc(pat->patlen)) == NULL)
goto mem;
memcpy(pat->pat, pb, pat->patlen);
/* get skip delta */
if ((pat->delta = malloc(256 * sizeof(*d))) == NULL)
goto mem;
for (j = 0, d = pat->delta; j < 256; j++)
d[j] = pat->patlen;
for (pe = pb + pat->patlen - 1; pb <= pe; pb++)
d[*pb] = pe - pb;
if (freq == NULL) /* default freq table */
freq = freq_def;
r = 0; /* get guard */
for (pb = pat->pat, pe = pb + pat->patlen - 1; pb < pe; pb++)
if (freq[*pb] < freq[pat->pat[r]])
r = pb - pat->pat;
pat->rarec = pat->pat[r];
pat->rareoff = r - (pat->patlen - 1);
/* get md2 shift */
for (pe = pat->pat + pat->patlen - 1, p = pe - 1; p >= pat->pat; p--)
if (*p == *pe)
break;
/* *p is first leftward reoccurrence of *pe */
pat->md2 = pe - p;
return (pat);
mem: sv_errno = errno;
bm_free(pat);
errno = sv_errno;
return (NULL);
}
void
bm_free(bm_pat *pat)
{
if (pat->pat != NULL)
free(pat->pat);
if (pat->delta != NULL)
free(pat->delta);
free(pat);
}
u_char *
bm_exec(bm_pat *pat, u_char *base, size_t n)
{
u_char *e, *ep, *p, *q, *s;
size_t *d0, k, md2, n1, ro;
int rc;
if (n == 0)
return (NULL);
d0 = pat->delta;
n1 = pat->patlen - 1;
md2 = pat->md2;
ro = pat->rareoff;
rc = pat->rarec;
ep = pat->pat + pat->patlen - 1;
s = base + (pat->patlen - 1);
/* fast loop up to n - 3 * patlen */
e = base + n - 3 * pat->patlen;
while (s < e) {
k = d0[*s]; /* ufast skip loop */
while (k) {
k = d0[*(s += k)];
k = d0[*(s += k)];
}
if (s >= e)
break;
if (s[ro] != rc) /* guard test */
goto mismatch1;
/* fwd match */
for (p = pat->pat, q = s - n1; p < ep;)
if (*q++ != *p++)
goto mismatch1;
return (s - n1);
mismatch1: s += md2; /* md2 shift */
}
/* slow loop up to end */
e = base + n;
while (s < e) {
s += d0[*s]; /* step */
if (s >= e)
break;
if (s[ro] != rc) /* guard test */
goto mismatch2;
/* fwd match */
for (p = pat->pat, q = s - n1; p <= ep;)
if (*q++ != *p++)
goto mismatch2;
return (s - n1);
mismatch2: s += md2; /* md2 shift */
}
return (NULL);
}
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