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
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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
36 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved.
37 * @(#)look.c 8.2 (Berkeley) 5/4/95
38 * $FreeBSD: src/usr.bin/look/look.c,v 1.11 1999/08/28 01:03:14 peter Exp $
39 * $DragonFly: src/usr.bin/look/look.c,v 1.3 2003/10/04 20:36:48 hmp Exp $
43 * look -- find lines in a sorted list.
45 * The man page said that TABs and SPACEs participate in -d comparisons.
46 * In fact, they were ignored. This implements historic practice, not
50 #include <sys/types.h>
65 #include "pathnames.h"
68 * FOLD and DICT convert characters to a normal form for comparison,
69 * according to the user specified flags.
71 * DICT expects integers because it uses a non-character value to
72 * indicate a character which should not participate in comparisons.
77 #define NO_COMPARE (-2)
79 #define FOLD(c) (isupper(c) ? tolower(c) : (unsigned char) (c))
80 #define DICT(c) (isalnum(c) ? (c) & 0xFF /* int */ : NO_COMPARE)
84 char *binary_search(unsigned char *, unsigned char *, unsigned char *);
85 int compare(unsigned char *, unsigned char *, unsigned char *);
86 char *linear_search(unsigned char *, unsigned char *, unsigned char *);
87 int look(unsigned char *, unsigned char *, unsigned char *);
88 void print_from(unsigned char *, unsigned char *, unsigned char *);
90 static void usage(void);
93 main(int argc, char **argv)
96 int ch, fd, termchar, match;
97 unsigned char *back, *file, *front, *string, *p;
99 (void) setlocale(LC_CTYPE, "");
103 while ((ch = getopt(argc, argv, "dft:")) != -1)
123 if (argc == 1) /* But set -df by default. */
129 if (termchar != '\0' && (p = strchr(string, termchar)) != NULL)
134 if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
136 if (sb.st_size > SIZE_T_MAX)
137 errx(2, "%s: %s", file, strerror(EFBIG));
138 if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED)
140 back = front + sb.st_size;
141 match *= (look(string, front, back));
143 } while (argc-- > 2 && (file = *argv++));
149 look(unsigned char *string, unsigned char *front, unsigned char *back)
152 register unsigned char *readp, *writep;
154 /* Reformat string string to avoid doing it multiple times later. */
155 for (readp = writep = string; ch = *readp++;) {
160 if (ch != NO_COMPARE)
165 front = binary_search(string, front, back);
166 front = linear_search(string, front, back);
169 print_from(string, front, back);
170 return (front ? 0 : 1);
175 * Binary search for "string" in memory between "front" and "back".
177 * This routine is expected to return a pointer to the start of a line at
178 * *or before* the first word matching "string". Relaxing the constraint
179 * this way simplifies the algorithm.
182 * front points to the beginning of a line at or before the first
185 * back points to the beginning of a line at or after the first
188 * Base of the Invariants.
192 * Advancing the Invariants:
194 * p = first newline after halfway point from front to back.
196 * If the string at "p" is not greater than the string to match,
197 * p is the new front. Otherwise it is the new back.
201 * The definition of the routine allows it return at any point,
202 * since front is always at or before the line to print.
204 * In fact, it returns when the chosen "p" equals "back". This
205 * implies that there exists a string is least half as long as
206 * (back - front), which in turn implies that a linear search will
207 * be no more expensive than the cost of simply printing a string or two.
209 * Trying to continue with binary search at this point would be
210 * more trouble than it's worth.
212 #define SKIP_PAST_NEWLINE(p, back) \
213 while (p < back && *p++ != '\n');
216 binary_search(register unsigned char *string, register unsigned char *front,
217 register unsigned char *back)
219 register unsigned char *p;
221 p = front + (back - front) / 2;
222 SKIP_PAST_NEWLINE(p, back);
225 * If the file changes underneath us, make sure we don't
228 while (p < back && back > front) {
229 if (compare(string, p, back) == GREATER)
233 p = front + (back - front) / 2;
234 SKIP_PAST_NEWLINE(p, back);
240 * Find the first line that starts with string, linearly searching from front
243 * Return NULL for no such line.
245 * This routine assumes:
247 * o front points at the first character in a line.
248 * o front is before or at the first line to be printed.
251 linear_search(unsigned char *string, unsigned char *front, unsigned char *back)
253 while (front < back) {
254 switch (compare(string, front, back)) {
255 case EQUAL: /* Found it. */
258 case LESS: /* No such string. */
261 case GREATER: /* Keep going. */
264 SKIP_PAST_NEWLINE(front, back);
270 * Print as many lines as match string, starting at front.
273 print_from(register unsigned char *string, register unsigned char *front,
274 register unsigned char *back)
276 for (; front < back && compare(string, front, back) == EQUAL; ++front) {
277 for (; front < back && *front != '\n'; ++front)
278 if (putchar(*front) == EOF)
280 if (putchar('\n') == EOF)
286 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
287 * string2 (s1 ??? s2).
289 * o Matches up to len(s1) are EQUAL.
290 * o Matches up to len(s2) are GREATER.
292 * Compare understands about the -f and -d flags, and treats comparisons
295 * The string "s1" is null terminated. The string s2 is '\n' terminated (or
296 * "back" terminated).
299 compare(register unsigned char *s1, register unsigned char *s2,
300 register unsigned char *back)
304 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) {
311 if (ch == NO_COMPARE) {
312 ++s2; /* Ignore character in comparison. */
316 return (*s1 < ch ? LESS : GREATER);
318 return (*s1 ? GREATER : EQUAL);
324 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n");