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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved.
33 * @(#)look.c 8.2 (Berkeley) 5/4/95
34 * $FreeBSD: head/usr.bin/look/look.c 268242 2014-07-04 04:47:29Z eadler $
38 * look -- find lines in a sorted list.
40 * The man page said that TABs and SPACEs participate in -d comparisons.
41 * In fact, they were ignored. This implements historic practice, not
45 #include <sys/types.h>
63 #include "pathnames.h"
65 static char _path_words[] = _PATH_WORDS;
71 static int dflag, fflag;
73 static char *binary_search(wchar_t *, unsigned char *, unsigned char *);
74 static int compare(wchar_t *, unsigned char *, unsigned char *);
75 static char *linear_search(wchar_t *, unsigned char *, unsigned char *);
76 static int look(wchar_t *, unsigned char *, unsigned char *);
77 static wchar_t *prepkey(const char *, wchar_t);
78 static void print_from(wchar_t *, unsigned char *, unsigned char *);
80 static void usage(void);
82 static struct option longopts[] = {
83 { "alternative",no_argument, NULL, 'a' },
84 { "alphanum", no_argument, NULL, 'd' },
85 { "ignore-case",no_argument, NULL, 'i' },
86 { "terminate", required_argument, NULL, 't'},
91 main(int argc, char *argv[])
96 unsigned char *back, *front;
97 unsigned const char *file;
100 setlocale(LC_CTYPE, "");
104 while ((ch = getopt_long(argc, argv, "+adft:", longopts, NULL)) != -1)
116 if (mbrtowc(&termchar, optarg, MB_LEN_MAX, NULL) !=
118 errx(2, "invalid termination character");
129 if (argc == 1) /* But set -df by default. */
131 key = prepkey(*argv++, termchar);
138 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
140 if ((uintmax_t)sb.st_size > (uintmax_t)SIZE_T_MAX)
141 errx(2, "%s: %s", file, strerror(EFBIG));
142 if (sb.st_size == 0) {
146 if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED)
148 back = front + sb.st_size;
149 match *= (look(key, front, back));
151 } while (argc-- > 2 && (file = *argv++));
157 prepkey(const char *string, wchar_t termchar)
160 wchar_t *key, *writep;
165 * Reformat search string and convert to wide character representation
166 * to avoid doing it multiple times later.
168 if ((key = malloc(sizeof(wchar_t) * (strlen(string) + 1))) == NULL)
172 while ((clen = mbrtowc(&ch, readp, MB_LEN_MAX, NULL)) != 0) {
173 if (clen == (size_t)-1 || clen == (size_t)-2)
174 errc(2, EILSEQ, NULL);
177 if (!dflag || iswalnum(ch))
182 if (termchar != L'\0' && (writep = wcschr(key, termchar)) != NULL)
188 look(wchar_t *string, unsigned char *front, unsigned char *back)
190 front = binary_search(string, front, back);
191 front = linear_search(string, front, back);
194 print_from(string, front, back);
195 return (front ? 0 : 1);
200 * Binary search for "string" in memory between "front" and "back".
202 * This routine is expected to return a pointer to the start of a line at
203 * *or before* the first word matching "string". Relaxing the constraint
204 * this way simplifies the algorithm.
207 * front points to the beginning of a line at or before the first
210 * back points to the beginning of a line at or after the first
213 * Base of the Invariants.
217 * Advancing the Invariants:
219 * p = first newline after halfway point from front to back.
221 * If the string at "p" is not greater than the string to match,
222 * p is the new front. Otherwise it is the new back.
226 * The definition of the routine allows it return at any point,
227 * since front is always at or before the line to print.
229 * In fact, it returns when the chosen "p" equals "back". This
230 * implies that there exists a string is least half as long as
231 * (back - front), which in turn implies that a linear search will
232 * be no more expensive than the cost of simply printing a string or two.
234 * Trying to continue with binary search at this point would be
235 * more trouble than it's worth.
237 #define SKIP_PAST_NEWLINE(p, back) \
238 while (p < back && *p++ != '\n');
241 binary_search(wchar_t *string, unsigned char *front, unsigned char *back)
245 p = front + (back - front) / 2;
246 SKIP_PAST_NEWLINE(p, back);
249 * If the file changes underneath us, make sure we don't
252 while (p < back && back > front) {
253 if (compare(string, p, back) == GREATER)
257 p = front + (back - front) / 2;
258 SKIP_PAST_NEWLINE(p, back);
264 * Find the first line that starts with string, linearly searching from front
267 * Return NULL for no such line.
269 * This routine assumes:
271 * o front points at the first character in a line.
272 * o front is before or at the first line to be printed.
275 linear_search(wchar_t *string, unsigned char *front, unsigned char *back)
277 while (front < back) {
278 switch (compare(string, front, back)) {
279 case EQUAL: /* Found it. */
281 case LESS: /* No such string. */
283 case GREATER: /* Keep going. */
286 SKIP_PAST_NEWLINE(front, back);
292 * Print as many lines as match string, starting at front.
295 print_from(wchar_t *string, unsigned char *front, unsigned char *back)
297 for (; front < back && compare(string, front, back) == EQUAL; ++front) {
298 for (; front < back && *front != '\n'; ++front)
299 if (putchar(*front) == EOF)
301 if (putchar('\n') == EOF)
307 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
308 * string2 (s1 ??? s2).
310 * o Matches up to len(s1) are EQUAL.
311 * o Matches up to len(s2) are GREATER.
313 * Compare understands about the -f and -d flags, and treats comparisons
316 * The string "s1" is null terminated. The string s2 is '\n' terminated (or
317 * "back" terminated).
320 compare(wchar_t *s1, unsigned char *s2, unsigned char *back)
325 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, s2 += len2) {
327 len2 = mbrtowc(&ch2, s2, back - s2, NULL);
328 if (len2 == (size_t)-1 || len2 == (size_t)-2) {
334 if (dflag && !iswalnum(ch2)) {
335 /* Ignore character in comparison. */
340 return (ch1 < ch2 ? LESS : GREATER);
342 return (*s1 ? GREATER : EQUAL);
348 fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n");