2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * David Hitz of Auspex Systems, Inc.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 /* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
38 * - added Native Language Support
42 * look -- find lines in a sorted list.
44 * The man page said that TABs and SPACEs participate in -d comparisons.
45 * In fact, they were ignored. This implements historic practice, not
49 #include <sys/types.h>
62 #include "pathnames.h"
70 /* uglified the source a bit with globals, so that we only need
71 to allocate comparbuf once */
76 static char *binary_search (char *, char *);
77 static int compare (char *, char *);
78 static void err (const char *fmt, ...);
79 static char *linear_search (char *, char *);
80 static int look (char *, char *);
81 static void print_from (char *, char *);
82 static void usage (void);
85 main(int argc, char *argv[])
89 char *back, *file, *front, *p;
91 setlocale(LC_ALL, "");
92 bindtextdomain(PACKAGE, LOCALEDIR);
95 setlocale(LC_ALL, "");
99 string = NULL; /* just for gcc */
101 while ((ch = getopt(argc, argv, "adft:")) != -1)
104 file = _PATH_WORDS_ALT;
123 case 2: /* Don't set -df for user. */
127 case 1: /* But set -df by default. */
135 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL)
138 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
139 err("%s: %s", file, strerror(errno));
140 front = mmap(NULL, (size_t) sb.st_size, PROT_READ,
144 MAP_SHARED, fd, (off_t) 0);
147 (front == MAP_FAILED)
149 ((void *)(front) <= (void *)0)
151 err("%s: %s", file, strerror(errno));
154 /* workaround for mmap problem (rmiller@duskglow.com) */
155 if (front == (void *)0)
159 back = front + sb.st_size;
160 return look(front, back);
164 look(char *front, char *back)
167 char *readp, *writep;
169 /* Reformat string string to avoid doing it multiple times later. */
171 for (readp = writep = string; (ch = *readp++) != 0;) {
176 stringlen = writep - string;
178 stringlen = strlen(string);
180 comparbuf = malloc(stringlen+1);
181 if (comparbuf == NULL)
182 err(_("Out of memory"));
184 front = binary_search(front, back);
185 front = linear_search(front, back);
188 print_from(front, back);
189 return (front ? 0 : 1);
194 * Binary search for "string" in memory between "front" and "back".
196 * This routine is expected to return a pointer to the start of a line at
197 * *or before* the first word matching "string". Relaxing the constraint
198 * this way simplifies the algorithm.
201 * front points to the beginning of a line at or before the first
204 * back points to the beginning of a line at or after the first
207 * Advancing the Invariants:
209 * p = first newline after halfway point from front to back.
211 * If the string at "p" is not greater than the string to match,
212 * p is the new front. Otherwise it is the new back.
216 * The definition of the routine allows it return at any point,
217 * since front is always at or before the line to print.
219 * In fact, it returns when the chosen "p" equals "back". This
220 * implies that there exists a string is least half as long as
221 * (back - front), which in turn implies that a linear search will
222 * be no more expensive than the cost of simply printing a string or two.
224 * Trying to continue with binary search at this point would be
225 * more trouble than it's worth.
227 #define SKIP_PAST_NEWLINE(p, back) \
228 while (p < back && *p++ != '\n');
231 binary_search(char *front, char *back)
235 p = front + (back - front) / 2;
236 SKIP_PAST_NEWLINE(p, back);
239 * If the file changes underneath us, make sure we don't
242 while (p < back && back > front) {
243 if (compare(p, back) == GREATER)
247 p = front + (back - front) / 2;
248 SKIP_PAST_NEWLINE(p, back);
254 * Find the first line that starts with string, linearly searching from front
257 * Return NULL for no such line.
259 * This routine assumes:
261 * o front points at the first character in a line.
262 * o front is before or at the first line to be printed.
265 linear_search(char *front, char *back)
267 while (front < back) {
268 switch (compare(front, back)) {
269 case EQUAL: /* Found it. */
272 case LESS: /* No such string. */
275 case GREATER: /* Keep going. */
278 SKIP_PAST_NEWLINE(front, back);
284 * Print as many lines as match string, starting at front.
287 print_from(char *front, char *back)
291 while (front < back && compare(front, back) == EQUAL) {
292 if (compare(front, back) == EQUAL) {
294 while (front < back && !eol) {
295 if (putchar(*front) == EOF)
296 err("stdout: %s", strerror(errno));
297 if (*front++ == '\n')
301 SKIP_PAST_NEWLINE(front, back);
306 * Return LESS, GREATER, or EQUAL depending on how string compares with
307 * string2 (s1 ??? s2).
309 * o Matches up to len(s1) are EQUAL.
310 * o Matches up to len(s2) are GREATER.
312 * Compare understands about the -f and -d flags, and treats comparisons
315 * The string "string" is null terminated. The string "s2" is '\n' terminated
316 * (or "s2end" terminated).
318 * We use strcasecmp etc, since it knows how to ignore case also
322 compare(char *s2, char *s2end) {
326 /* copy, ignoring things that should be ignored */
329 while(s2 < s2end && *s2 != '\n' && i) {
330 if (!dflag || isalnum(*s2))
341 i = strncasecmp(comparbuf, string, stringlen);
343 i = strncmp(comparbuf, string, stringlen);
345 return ((i > 0) ? LESS : (i < 0) ? GREATER : EQUAL);
351 (void)fprintf(stderr, _("usage: look [-dfa] [-t char] string [file]\n"));
363 err(const char *fmt, ...)
376 (void)fprintf(stderr, "look: ");
377 (void)vfprintf(stderr, fmt, ap);
379 (void)fprintf(stderr, "\n");