/* $OpenBSD: bm.c,v 1.2 1996/03/09 02:42:55 niklas 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. */ #if defined(LIBC_SCCS) && !defined(lint) /* from: static char sccsid[] = "@(#)bm.c 8.7 (Berkeley) 6/21/94"; */ static char *rcsid = "$Id: bm.c,v 1.2 1996/03/09 02:42:55 niklas Exp $"; #endif /* LIBC_SCCS && not lint */ #include #include #include #include #include /* * 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(pb, len, freq) u_char const *pb; size_t len; u_char const *freq; { register u_char const *pe, *p; register size_t *d, r; register 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(pat) bm_pat *pat; { if (pat->pat != NULL) free(pat->pat); if (pat->delta != NULL) free(pat->delta); free(pat); } u_char * bm_exec(pat, base, n) bm_pat *pat; u_char *base; size_t n; { register u_char *e, *ep, *p, *q, *s; register size_t *d0, k, md2, n1, ro; register 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); }