1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * David Hitz of Auspex Systems, Inc.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
23 *
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
34 * SUCH DAMAGE.
35 */
36
37#ifndef lint
38static const char copyright[] =
39"@(#) Copyright (c) 1991, 1993\n\
40	The Regents of the University of California.  All rights reserved.\n";
41#endif /* not lint */
42
43#ifndef lint
44#if 0
45static char sccsid[] = "@(#)look.c	8.2 (Berkeley) 5/4/95";
46#endif
47#endif /* not lint */
48#include <sys/cdefs.h>
49__FBSDID("$FreeBSD: src/usr.bin/look/look.c,v 1.18.10.2.4.1 2010/06/14 02:09:06 kensmith Exp $");
50
51/*
52 * look -- find lines in a sorted list.
53 *
54 * The man page said that TABs and SPACEs participate in -d comparisons.
55 * In fact, they were ignored.  This implements historic practice, not
56 * the manual page.
57 */
58
59#include <sys/types.h>
60#include <sys/mman.h>
61#include <sys/stat.h>
62
63#include <err.h>
64#include <errno.h>
65#include <fcntl.h>
66#include <limits.h>
67#include <locale.h>
68#include <stdio.h>
69#include <stdlib.h>
70#include <string.h>
71#include <unistd.h>
72#include <wchar.h>
73#include <wctype.h>
74
75#include "pathnames.h"
76
77static char _path_words[] = _PATH_WORDS;
78
79#define	EQUAL		0
80#define	GREATER		1
81#define	LESS		(-1)
82
83int dflag, fflag;
84
85char    *binary_search(wchar_t *, unsigned char *, unsigned char *);
86int      compare(wchar_t *, unsigned char *, unsigned char *);
87char    *linear_search(wchar_t *, unsigned char *, unsigned char *);
88int      look(wchar_t *, unsigned char *, unsigned char *);
89wchar_t	*prepkey(const char *, wchar_t);
90void     print_from(wchar_t *, unsigned char *, unsigned char *);
91
92static void usage(void);
93
94int
95main(int argc, char *argv[])
96{
97	struct stat sb;
98	int ch, fd, match;
99	wchar_t termchar;
100	unsigned char *back, *front;
101	unsigned const char *file;
102	wchar_t *key;
103
104	(void) setlocale(LC_CTYPE, "");
105
106	file = _path_words;
107	termchar = L'\0';
108	while ((ch = getopt(argc, argv, "dft:")) != -1)
109		switch(ch) {
110		case 'd':
111			dflag = 1;
112			break;
113		case 'f':
114			fflag = 1;
115			break;
116		case 't':
117			if (mbrtowc(&termchar, optarg, MB_LEN_MAX, NULL) !=
118			    strlen(optarg))
119				errx(2, "invalid termination character");
120			break;
121		case '?':
122		default:
123			usage();
124		}
125	argc -= optind;
126	argv += optind;
127
128/* 4384130 */
129#ifdef __APPLE__
130	if (argc <= 0)
131#else
132	if (argc == 0)
133#endif
134		usage();
135	if (argc == 1) 			/* But set -df by default. */
136		dflag = fflag = 1;
137	key = prepkey(*argv++, termchar);
138	if (argc >= 2)
139		file = *argv++;
140
141	match = 1;
142
143	do {
144		if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
145			err(2, "%s", file);
146		if (sb.st_size > SIZE_T_MAX)
147			errx(2, "%s: %s", file, strerror(EFBIG));
148		if (sb.st_size == 0) {
149			close(fd);
150			continue;
151		}
152		if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED)
153			err(2, "%s", file);
154		back = front + sb.st_size;
155		match *= (look(key, front, back));
156		close(fd);
157	} while (argc-- > 2 && (file = *argv++));
158
159	exit(match);
160}
161
162wchar_t *
163prepkey(const char *string, wchar_t termchar)
164{
165	const char *readp;
166	wchar_t *key, *writep;
167	wchar_t ch;
168	size_t clen;
169
170	/*
171	 * Reformat search string and convert to wide character representation
172	 * to avoid doing it multiple times later.
173	 */
174	if ((key = malloc(sizeof(wchar_t) * (strlen(string) + 1))) == NULL)
175		err(2, NULL);
176	readp = string;
177	writep = key;
178	while ((clen = mbrtowc(&ch, readp, MB_LEN_MAX, NULL)) != 0) {
179		if (clen == (size_t)-1 || clen == (size_t)-2)
180			errc(2, EILSEQ, NULL);
181		if (fflag)
182			ch = towlower(ch);
183		if (!dflag || iswalnum(ch))
184			*writep++ = ch;
185		readp += clen;
186	}
187	*writep = L'\0';
188	if (termchar != L'\0' && (writep = wcschr(key, termchar)) != NULL)
189		*++writep = L'\0';
190	return (key);
191}
192
193int
194look(wchar_t *string, unsigned char *front, unsigned char *back)
195{
196
197	front = binary_search(string, front, back);
198	front = linear_search(string, front, back);
199
200	if (front)
201		print_from(string, front, back);
202	return (front ? 0 : 1);
203}
204
205
206/*
207 * Binary search for "string" in memory between "front" and "back".
208 *
209 * This routine is expected to return a pointer to the start of a line at
210 * *or before* the first word matching "string".  Relaxing the constraint
211 * this way simplifies the algorithm.
212 *
213 * Invariants:
214 * 	front points to the beginning of a line at or before the first
215 *	matching string.
216 *
217 * 	back points to the beginning of a line at or after the first
218 *	matching line.
219 *
220 * Base of the Invariants.
221 * 	front = NULL;
222 *	back = EOF;
223 *
224 * Advancing the Invariants:
225 *
226 * 	p = first newline after halfway point from front to back.
227 *
228 * 	If the string at "p" is not greater than the string to match,
229 *	p is the new front.  Otherwise it is the new back.
230 *
231 * Termination:
232 *
233 * 	The definition of the routine allows it return at any point,
234 *	since front is always at or before the line to print.
235 *
236 * 	In fact, it returns when the chosen "p" equals "back".  This
237 *	implies that there exists a string is least half as long as
238 *	(back - front), which in turn implies that a linear search will
239 *	be no more expensive than the cost of simply printing a string or two.
240 *
241 * 	Trying to continue with binary search at this point would be
242 *	more trouble than it's worth.
243 */
244#define	SKIP_PAST_NEWLINE(p, back) \
245	while (p < back && *p++ != '\n');
246
247char *
248binary_search(wchar_t *string, unsigned char *front, unsigned char *back)
249{
250	unsigned char *p;
251
252	p = front + (back - front) / 2;
253	SKIP_PAST_NEWLINE(p, back);
254
255	/*
256	 * If the file changes underneath us, make sure we don't
257	 * infinitely loop.
258	 */
259	while (p < back && back > front) {
260		if (compare(string, p, back) == GREATER)
261			front = p;
262		else
263			back = p;
264		p = front + (back - front) / 2;
265		SKIP_PAST_NEWLINE(p, back);
266	}
267	return (front);
268}
269
270/*
271 * Find the first line that starts with string, linearly searching from front
272 * to back.
273 *
274 * Return NULL for no such line.
275 *
276 * This routine assumes:
277 *
278 * 	o front points at the first character in a line.
279 *	o front is before or at the first line to be printed.
280 */
281char *
282linear_search(wchar_t *string, unsigned char *front, unsigned char *back)
283{
284	while (front < back) {
285		switch (compare(string, front, back)) {
286		case EQUAL:		/* Found it. */
287			return (front);
288		case LESS:		/* No such string. */
289			return (NULL);
290		case GREATER:		/* Keep going. */
291			break;
292		}
293		SKIP_PAST_NEWLINE(front, back);
294	}
295	return (NULL);
296}
297
298/*
299 * Print as many lines as match string, starting at front.
300 */
301void
302print_from(wchar_t *string, unsigned char *front, unsigned char *back)
303{
304	for (; front < back && compare(string, front, back) == EQUAL; ++front) {
305		for (; front < back && *front != '\n'; ++front)
306			if (putchar(*front) == EOF)
307				err(2, "stdout");
308		if (putchar('\n') == EOF)
309			err(2, "stdout");
310	}
311}
312
313/*
314 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
315 * string2 (s1 ??? s2).
316 *
317 * 	o Matches up to len(s1) are EQUAL.
318 *	o Matches up to len(s2) are GREATER.
319 *
320 * Compare understands about the -f and -d flags, and treats comparisons
321 * appropriately.
322 *
323 * The string "s1" is null terminated.  The string s2 is '\n' terminated (or
324 * "back" terminated).
325 */
326int
327compare(wchar_t *s1, unsigned char *s2, unsigned char *back)
328{
329	wchar_t ch1, ch2;
330	size_t len2;
331
332	for (; *s1 && s2 < back && *s2 != '\n'; ++s1, s2 += len2) {
333		ch1 = *s1;
334		len2 = mbrtowc(&ch2, s2, back - s2, NULL);
335		if (len2 == (size_t)-1 || len2 == (size_t)-2) {
336			ch2 = *s2;
337			len2 = 1;
338		}
339		if (fflag)
340			ch2 = towlower(ch2);
341		if (dflag && !iswalnum(ch2)) {
342			/* Ignore character in comparison. */
343			--s1;
344			continue;
345		}
346		if (ch1 != ch2)
347			return (ch1 < ch2 ? LESS : GREATER);
348	}
349	return (*s1 ? GREATER : EQUAL);
350}
351
352static void
353usage(void)
354{
355	(void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n");
356	exit(2);
357}
358