1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * David Hitz of Auspex Systems, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35/*
36 * look -- find lines in a sorted list.
37 *
38 * The man page said that TABs and SPACEs participate in -d comparisons.
39 * In fact, they were ignored.  This implements historic practice, not
40 * the manual page.
41 */
42
43#include <sys/types.h>
44#include <sys/mman.h>
45#include <sys/stat.h>
46
47#include <err.h>
48#include <errno.h>
49#include <fcntl.h>
50#include <getopt.h>
51#include <limits.h>
52#include <locale.h>
53#include <stdint.h>
54#include <stdio.h>
55#include <stdlib.h>
56#include <string.h>
57#include <unistd.h>
58#include <wchar.h>
59#include <wctype.h>
60
61#include "pathnames.h"
62
63static char _path_words[] = _PATH_WORDS;
64
65#define	EQUAL		0
66#define	GREATER		1
67#define	LESS		(-1)
68
69static int dflag, fflag;
70
71static char	*binary_search(wchar_t *, unsigned char *, unsigned char *);
72static int	 compare(wchar_t *, unsigned char *, unsigned char *);
73static char	*linear_search(wchar_t *, unsigned char *, unsigned char *);
74static int	 look(wchar_t *, unsigned char *, unsigned char *);
75static wchar_t	*prepkey(const char *, wchar_t);
76static void	 print_from(wchar_t *, unsigned char *, unsigned char *);
77
78static void usage(void) __dead2;
79
80static struct option longopts[] = {
81	{ "alternative",no_argument,	NULL, 'a' },
82	{ "alphanum",	no_argument,	NULL, 'd' },
83	{ "ignore-case",no_argument,	NULL, 'i' },
84	{ "terminate",	required_argument, NULL, 't'},
85	{ NULL,		0,		NULL, 0 },
86};
87
88int
89main(int argc, char *argv[])
90{
91	struct stat sb;
92	int ch, fd, match;
93	wchar_t termchar;
94	unsigned char *back, *front;
95	unsigned const char *file;
96	wchar_t *key;
97
98	(void) setlocale(LC_CTYPE, "");
99
100	file = _path_words;
101	termchar = L'\0';
102	while ((ch = getopt_long(argc, argv, "+adft:", longopts, NULL)) != -1)
103		switch(ch) {
104		case 'a':
105			/* COMPATIBILITY */
106			break;
107		case 'd':
108			dflag = 1;
109			break;
110		case 'f':
111			fflag = 1;
112			break;
113		case 't':
114			if (mbrtowc(&termchar, optarg, MB_LEN_MAX, NULL) !=
115			    strlen(optarg))
116				errx(2, "invalid termination character");
117			break;
118		case '?':
119		default:
120			usage();
121		}
122	argc -= optind;
123	argv += optind;
124
125	if (argc == 0)
126		usage();
127	if (argc == 1) 			/* But set -df by default. */
128		dflag = fflag = 1;
129	key = prepkey(*argv++, termchar);
130	if (argc >= 2)
131		file = *argv++;
132
133	match = 1;
134
135	do {
136		if ((fd = open(file, O_RDONLY, 0)) < 0 || fstat(fd, &sb))
137			err(2, "%s", file);
138		if ((uintmax_t)sb.st_size > (uintmax_t)SIZE_T_MAX)
139			errx(2, "%s: %s", file, strerror(EFBIG));
140		if (sb.st_size == 0) {
141			close(fd);
142			continue;
143		}
144		if ((front = mmap(NULL, (size_t)sb.st_size, PROT_READ, MAP_SHARED, fd, (off_t)0)) == MAP_FAILED)
145			err(2, "%s", file);
146		back = front + sb.st_size;
147		match *= (look(key, front, back));
148		close(fd);
149	} while (argc-- > 2 && (file = *argv++));
150
151	exit(match);
152}
153
154static wchar_t *
155prepkey(const char *string, wchar_t termchar)
156{
157	const char *readp;
158	wchar_t *key, *writep;
159	wchar_t ch;
160	size_t clen;
161
162	/*
163	 * Reformat search string and convert to wide character representation
164	 * to avoid doing it multiple times later.
165	 */
166	if ((key = malloc(sizeof(wchar_t) * (strlen(string) + 1))) == NULL)
167		err(2, NULL);
168	readp = string;
169	writep = key;
170	while ((clen = mbrtowc(&ch, readp, MB_LEN_MAX, NULL)) != 0) {
171		if (clen == (size_t)-1 || clen == (size_t)-2)
172			errc(2, EILSEQ, NULL);
173		if (fflag)
174			ch = towlower(ch);
175		if (!dflag || iswalnum(ch))
176			*writep++ = ch;
177		readp += clen;
178	}
179	*writep = L'\0';
180	if (termchar != L'\0' && (writep = wcschr(key, termchar)) != NULL)
181		*++writep = L'\0';
182	return (key);
183}
184
185static int
186look(wchar_t *string, unsigned char *front, unsigned char *back)
187{
188
189	front = binary_search(string, front, back);
190	front = linear_search(string, front, back);
191
192	if (front)
193		print_from(string, front, back);
194	return (front ? 0 : 1);
195}
196
197
198/*
199 * Binary search for "string" in memory between "front" and "back".
200 *
201 * This routine is expected to return a pointer to the start of a line at
202 * *or before* the first word matching "string".  Relaxing the constraint
203 * this way simplifies the algorithm.
204 *
205 * Invariants:
206 * 	front points to the beginning of a line at or before the first
207 *	matching string.
208 *
209 * 	back points to the beginning of a line at or after the first
210 *	matching line.
211 *
212 * Base of the Invariants.
213 * 	front = NULL;
214 *	back = EOF;
215 *
216 * Advancing the Invariants:
217 *
218 * 	p = first newline after halfway point from front to back.
219 *
220 * 	If the string at "p" is not greater than the string to match,
221 *	p is the new front.  Otherwise it is the new back.
222 *
223 * Termination:
224 *
225 * 	The definition of the routine allows it return at any point,
226 *	since front is always at or before the line to print.
227 *
228 * 	In fact, it returns when the chosen "p" equals "back".  This
229 *	implies that there exists a string is least half as long as
230 *	(back - front), which in turn implies that a linear search will
231 *	be no more expensive than the cost of simply printing a string or two.
232 *
233 * 	Trying to continue with binary search at this point would be
234 *	more trouble than it's worth.
235 */
236#define	SKIP_PAST_NEWLINE(p, back) \
237	while (p < back && *p++ != '\n');
238
239static char *
240binary_search(wchar_t *string, unsigned char *front, unsigned char *back)
241{
242	unsigned char *p;
243
244	p = front + (back - front) / 2;
245	SKIP_PAST_NEWLINE(p, back);
246
247	/*
248	 * If the file changes underneath us, make sure we don't
249	 * infinitely loop.
250	 */
251	while (p < back && back > front) {
252		if (compare(string, p, back) == GREATER)
253			front = p;
254		else
255			back = p;
256		p = front + (back - front) / 2;
257		SKIP_PAST_NEWLINE(p, back);
258	}
259	return (front);
260}
261
262/*
263 * Find the first line that starts with string, linearly searching from front
264 * to back.
265 *
266 * Return NULL for no such line.
267 *
268 * This routine assumes:
269 *
270 * 	o front points at the first character in a line.
271 *	o front is before or at the first line to be printed.
272 */
273static char *
274linear_search(wchar_t *string, unsigned char *front, unsigned char *back)
275{
276	while (front < back) {
277		switch (compare(string, front, back)) {
278		case EQUAL:		/* Found it. */
279			return (front);
280		case LESS:		/* No such string. */
281			return (NULL);
282		case GREATER:		/* Keep going. */
283			break;
284		}
285		SKIP_PAST_NEWLINE(front, back);
286	}
287	return (NULL);
288}
289
290/*
291 * Print as many lines as match string, starting at front.
292 */
293static void
294print_from(wchar_t *string, unsigned char *front, unsigned char *back)
295{
296	for (; front < back && compare(string, front, back) == EQUAL; ++front) {
297		for (; front < back && *front != '\n'; ++front)
298			if (putchar(*front) == EOF)
299				err(2, "stdout");
300		if (putchar('\n') == EOF)
301			err(2, "stdout");
302	}
303}
304
305/*
306 * Return LESS, GREATER, or EQUAL depending on how the string1 compares with
307 * string2 (s1 ??? s2).
308 *
309 * 	o Matches up to len(s1) are EQUAL.
310 *	o Matches up to len(s2) are GREATER.
311 *
312 * Compare understands about the -f and -d flags, and treats comparisons
313 * appropriately.
314 *
315 * The string "s1" is null terminated.  The string s2 is '\n' terminated (or
316 * "back" terminated).
317 */
318static int
319compare(wchar_t *s1, unsigned char *s2, unsigned char *back)
320{
321	wchar_t ch1, ch2;
322	size_t len2;
323
324	for (; *s1 && s2 < back && *s2 != '\n'; ++s1, s2 += len2) {
325		ch1 = *s1;
326		len2 = mbrtowc(&ch2, s2, back - s2, NULL);
327		if (len2 == (size_t)-1 || len2 == (size_t)-2) {
328			ch2 = *s2;
329			len2 = 1;
330		}
331		if (fflag)
332			ch2 = towlower(ch2);
333		if (dflag && !iswalnum(ch2)) {
334			/* Ignore character in comparison. */
335			--s1;
336			continue;
337		}
338		if (ch1 != ch2)
339			return (ch1 < ch2 ? LESS : GREATER);
340	}
341	return (*s1 ? GREATER : EQUAL);
342}
343
344static void
345usage(void)
346{
347	(void)fprintf(stderr, "usage: look [-df] [-t char] string [file ...]\n");
348	exit(2);
349}
350