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
38 static char copyright[] =
39 "@(#) Copyright (c) 1991, 1993\n\
40 The Regents of the University of California. All rights reserved.\n";
44 static char sccsid[] = "@(#)look.c 8.1 (Berkeley) 6/14/93";
48 * look -- find lines in a sorted list.
50 * The man page said that TABs and SPACEs participate in -d comparisons.
51 * In fact, they were ignored. This implements historic practice, not
55 #include <sys/types.h>
66 #include "pathnames.h"
69 * FOLD and DICT convert characters to a normal form for comparison,
70 * according to the user specified flags.
72 * DICT expects integers because it uses a non-character value to
73 * indicate a character which should not participate in comparisons.
78 #define NO_COMPARE (-2)
80 #define FOLD(c) (isascii(c) && isupper(c) ? tolower(c) : (c))
81 #define DICT(c) (isascii(c) && isalnum(c) ? (c) : NO_COMPARE)
85 char *binary_search __P((char *, char *, char *));
86 int compare __P((char *, char *, char *));
87 void err __P((const char *fmt, ...));
88 char *linear_search __P((char *, char *, char *));
89 int look __P((char *, char *, char *));
90 void print_from __P((char *, char *, char *));
92 static void usage __P((void));
100 char *back, *file, *front, *string, *p;
104 while ((ch = getopt(argc, argv, "dft:")) != EOF)
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 if (sb.st_size > SIZE_T_MAX)
141 err("%s: %s", file, strerror(EFBIG));
142 if ((front = mmap(NULL,
143 (size_t)sb.st_size, PROT_READ, 0, fd, (off_t)0)) == NULL)
144 err("%s: %s", file, strerror(errno));
145 back = front + sb.st_size;
146 exit(look(string, front, back));
149 look(string, front, back)
150 char *string, *front, *back;
153 register char *readp, *writep;
155 /* Reformat string string to avoid doing it multiple times later. */
156 for (readp = writep = string; ch = *readp++;) {
161 if (ch != NO_COMPARE)
166 front = binary_search(string, front, back);
167 front = linear_search(string, front, back);
170 print_from(string, front, back);
171 return (front ? 0 : 1);
176 * Binary search for "string" in memory between "front" and "back".
178 * This routine is expected to return a pointer to the start of a line at
179 * *or before* the first word matching "string". Relaxing the constraint
180 * this way simplifies the algorithm.
183 * front points to the beginning of a line at or before the first
186 * back points to the beginning of a line at or after the first
189 * Base of the Invariants.
193 * Advancing the Invariants:
195 * p = first newline after halfway point from front to back.
197 * If the string at "p" is not greater than the string to match,
198 * p is the new front. Otherwise it is the new back.
202 * The definition of the routine allows it return at any point,
203 * since front is always at or before the line to print.
205 * In fact, it returns when the chosen "p" equals "back". This
206 * implies that there exists a string is least half as long as
207 * (back - front), which in turn implies that a linear search will
208 * be no more expensive than the cost of simply printing a string or two.
210 * Trying to continue with binary search at this point would be
211 * more trouble than it's worth.
213 #define SKIP_PAST_NEWLINE(p, back) \
214 while (p < back && *p++ != '\n');
217 binary_search(string, front, back)
218 register char *string, *front, *back;
222 p = front + (back - front) / 2;
223 SKIP_PAST_NEWLINE(p, back);
226 * If the file changes underneath us, make sure we don't
229 while (p < back && back > front) {
230 if (compare(string, p, back) == GREATER)
234 p = front + (back - front) / 2;
235 SKIP_PAST_NEWLINE(p, back);
241 * Find the first line that starts with string, linearly searching from front
244 * Return NULL for no such line.
246 * This routine assumes:
248 * o front points at the first character in a line.
249 * o front is before or at the first line to be printed.
252 linear_search(string, front, back)
253 char *string, *front, *back;
255 while (front < back) {
256 switch (compare(string, front, back)) {
257 case EQUAL: /* Found it. */
260 case LESS: /* No such string. */
263 case GREATER: /* Keep going. */
266 SKIP_PAST_NEWLINE(front, back);
272 * Print as many lines as match string, starting at front.
275 print_from(string, front, back)
276 register char *string, *front, *back;
278 for (; front < back && compare(string, front, back) == EQUAL; ++front) {
279 for (; front < back && *front != '\n'; ++front)
280 if (putchar(*front) == EOF)
281 err("stdout: %s", strerror(errno));
282 if (putchar('\n') == EOF)
283 err("stdout: %s", strerror(errno));
288 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
289 * string2 (s1 ??? s2).
291 * o Matches up to len(s1) are EQUAL.
292 * o Matches up to len(s2) are GREATER.
294 * Compare understands about the -f and -d flags, and treats comparisons
297 * The string "s1" is null terminated. The string s2 is '\n' terminated (or
298 * "back" terminated).
301 compare(s1, s2, back)
302 register char *s1, *s2, *back;
306 for (; *s1 && s2 < back && *s2 != '\n'; ++s1, ++s2) {
313 if (ch == NO_COMPARE) {
314 ++s2; /* Ignore character in comparison. */
318 return (*s1 < ch ? LESS : GREATER);
320 return (*s1 ? GREATER : EQUAL);
326 (void)fprintf(stderr, "usage: look [-df] [-t char] string [file]\n");
338 err(const char *fmt, ...)
351 (void)fprintf(stderr, "look: ");
352 (void)vfprintf(stderr, fmt, ap);
354 (void)fprintf(stderr, "\n");