195 lines
5.8 KiB
C
195 lines
5.8 KiB
C
/*
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* Copyright (c) 1989 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* James A. Woods.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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char copyright[] =
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"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
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All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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/*static char sccsid[] = "from: @(#)locate.c 5.2 (Berkeley) 6/1/90";*/
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static char rcsid[] = "$Id: locate.c,v 1.5 1993/08/01 18:13:45 mycroft Exp $";
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#endif /* not lint */
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/*
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* Ref: Usenix ;login:, Vol 8, No 1, February/March, 1983, p. 8.
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*
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* Locate scans a file list for the full pathname of a file given only part
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* of the name. The list has been processed with with "front-compression"
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* and bigram coding. Front compression reduces space by a factor of 4-5,
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* bigram coding by a further 20-25%.
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*
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* The codes are:
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*
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* 0-28 likeliest differential counts + offset to make nonnegative
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* 30 switch code for out-of-range count to follow in next word
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* 128-255 bigram codes (128 most common, as determined by 'updatedb')
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* 32-127 single character (printable) ascii residue (ie, literal)
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*
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* A novel two-tiered string search technique is employed:
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*
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* First, a metacharacter-free subpattern and partial pathname is matched
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* BACKWARDS to avoid full expansion of the pathname list. The time savings
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* is 40-50% over forward matching, which cannot efficiently handle
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* overlapped search patterns and compressed path residue.
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*
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* Then, the actual shell glob-style regular expression (if in this form) is
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* matched against the candidate pathnames using the slower routines provided
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* in the standard 'find'.
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*/
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#include <sys/param.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include <fnmatch.h>
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#include "locate.h"
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#include "pathnames.h"
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FILE *fp;
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main(argc, argv)
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int argc;
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char **argv;
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{
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if (argc != 2) {
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(void)fprintf(stderr, "usage: locate pattern\n");
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exit(1);
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}
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if (!(fp = fopen(_PATH_FCODES, "r"))) {
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(void)fprintf(stderr, "locate: no database file %s.\n",
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_PATH_FCODES);
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exit(1);
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}
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while (*++argv)
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fastfind(*argv);
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exit(0);
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}
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fastfind(pathpart)
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char *pathpart;
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{
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register char *p, *s;
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register int c;
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int count, found, globflag;
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char *cutoff, *patend, *q, *patprep();
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char bigram1[NBG], bigram2[NBG], path[MAXPATHLEN];
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for (c = 0, p = bigram1, s = bigram2; c < NBG; c++)
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p[c] = getc(fp), s[c] = getc(fp);
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p = pathpart;
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globflag = index(p, '*') || index(p, '?') || index(p, '[');
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patend = patprep(p);
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found = 0;
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for (c = getc(fp), count = 0; c != EOF;) {
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count += ((c == SWITCH) ? getw(fp) : c) - OFFSET;
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/* overlay old path */
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for (p = path + count; (c = getc(fp)) > SWITCH;)
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if (c < PARITY)
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*p++ = c;
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else { /* bigrams are parity-marked */
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c &= PARITY - 1;
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*p++ = bigram1[c], *p++ = bigram2[c];
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}
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*p-- = NULL;
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cutoff = (found ? path : path + count);
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for (found = 0, s = p; s >= cutoff; s--)
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if (*s == *patend) { /* fast first char check */
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for (p = patend - 1, q = s - 1; *p != NULL;
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p--, q--)
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if (*q != *p)
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break;
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if (*p == NULL) { /* fast match success */
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found = 1;
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if (!globflag ||
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!fnmatch(pathpart, path, 0))
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(void)printf("%s\n", path);
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break;
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}
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}
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}
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}
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/*
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* extract last glob-free subpattern in name for fast pre-match; prepend
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* '\0' for backwards match; return end of new pattern
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*/
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static char globfree[100];
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char *
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patprep(name)
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char *name;
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{
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register char *endmark, *p, *subp;
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subp = globfree;
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*subp++ = '\0';
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p = name + strlen(name) - 1;
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/* skip trailing metacharacters (and [] ranges) */
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for (; p >= name; p--)
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if (index("*?", *p) == 0)
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break;
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if (p < name)
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p = name;
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if (*p == ']')
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for (p--; p >= name; p--)
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if (*p == '[') {
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p--;
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break;
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}
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if (p < name)
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p = name;
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/*
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* if pattern has only metacharacters, check every path (force '/'
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* search)
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*/
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if ((p == name) && index("?*[]", *p) != 0)
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*subp++ = '/';
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else {
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for (endmark = p; p >= name; p--)
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if (index("]*?", *p) != 0)
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break;
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for (++p;
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(p <= endmark) && subp < (globfree + sizeof(globfree));)
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*subp++ = *p++;
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}
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*subp = '\0';
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return(--subp);
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}
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