xref: /freebsd/usr.bin/diff/diffreg.c (revision 2008043f386721d58158e37e0d7e50df8095942d)
1 /*	$OpenBSD: diffreg.c,v 1.93 2019/06/28 13:35:00 deraadt Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-4-Clause
5  *
6  * Copyright (C) Caldera International Inc.  2001-2002.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code and documentation must retain the above
13  *    copyright notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed or owned by Caldera
20  *	International, Inc.
21  * 4. Neither the name of Caldera International, Inc. nor the names of other
22  *    contributors may be used to endorse or promote products derived from
23  *    this software without specific prior written permission.
24  *
25  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
26  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
30  * INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
31  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
32  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
34  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
35  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 /*-
39  * Copyright (c) 1991, 1993
40  *	The Regents of the University of California.  All rights reserved.
41  *
42  * Redistribution and use in source and binary forms, with or without
43  * modification, are permitted provided that the following conditions
44  * are met:
45  * 1. Redistributions of source code must retain the above copyright
46  *    notice, this list of conditions and the following disclaimer.
47  * 2. Redistributions in binary form must reproduce the above copyright
48  *    notice, this list of conditions and the following disclaimer in the
49  *    documentation and/or other materials provided with the distribution.
50  * 3. Neither the name of the University nor the names of its contributors
51  *    may be used to endorse or promote products derived from this software
52  *    without specific prior written permission.
53  *
54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64  * SUCH DAMAGE.
65  *
66  *	@(#)diffreg.c   8.1 (Berkeley) 6/6/93
67  */
68 
69 #include <sys/cdefs.h>
70 #include <sys/capsicum.h>
71 #include <sys/stat.h>
72 
73 #include <capsicum_helpers.h>
74 #include <ctype.h>
75 #include <err.h>
76 #include <errno.h>
77 #include <fcntl.h>
78 #include <math.h>
79 #include <paths.h>
80 #include <regex.h>
81 #include <stdbool.h>
82 #include <stddef.h>
83 #include <stdint.h>
84 #include <stdio.h>
85 #include <stdlib.h>
86 #include <string.h>
87 
88 #include "pr.h"
89 #include "diff.h"
90 #include "xmalloc.h"
91 
92 /*
93  * diff - compare two files.
94  */
95 
96 /*
97  *	Uses an algorithm due to Harold Stone, which finds a pair of longest
98  *	identical subsequences in the two files.
99  *
100  *	The major goal is to generate the match vector J. J[i] is the index of
101  *	the line in file1 corresponding to line i file0. J[i] = 0 if there is no
102  *	such line in file1.
103  *
104  *	Lines are hashed so as to work in core. All potential matches are
105  *	located by sorting the lines of each file on the hash (called
106  *	``value''). In particular, this collects the equivalence classes in
107  *	file1 together. Subroutine equiv replaces the value of each line in
108  *	file0 by the index of the first element of its matching equivalence in
109  *	(the reordered) file1. To save space equiv squeezes file1 into a single
110  *	array member in which the equivalence classes are simply concatenated,
111  *	except that their first members are flagged by changing sign.
112  *
113  *	Next the indices that point into member are unsorted into array class
114  *	according to the original order of file0.
115  *
116  *	The cleverness lies in routine stone. This marches through the lines of
117  *	file0, developing a vector klist of "k-candidates". At step i
118  *	a k-candidate is a matched pair of lines x,y (x in file0 y in file1)
119  *	such that there is a common subsequence of length k between the first
120  *	i lines of file0 and the first y lines of file1, but there is no such
121  *	subsequence for any smaller y. x is the earliest possible mate to y that
122  *	occurs in such a subsequence.
123  *
124  *	Whenever any of the members of the equivalence class of lines in file1
125  *	matable to a line in file0 has serial number less than the y of some
126  *	k-candidate, that k-candidate with the smallest such y is replaced. The
127  *	new k-candidate is chained (via pred) to the current k-1 candidate so
128  *	that the actual subsequence can be recovered. When a member has serial
129  *	number greater that the y of all k-candidates, the klist is extended. At
130  *	the end, the longest subsequence is pulled out and placed in the array J
131  *	by unravel.
132  *
133  *	With J in hand, the matches there recorded are check'ed against reality
134  *	to assure that no spurious matches have crept in due to hashing. If they
135  *	have, they are broken, and "jackpot" is recorded -- a harmless matter
136  *	except that a true match for a spuriously mated line may now be
137  *	unnecessarily reported as a change.
138  *
139  *	Much of the complexity of the program comes simply from trying to
140  *	minimize core utilization and maximize the range of doable problems by
141  *	dynamically allocating what is needed and reusing what is not. The core
142  *	requirements for problems larger than somewhat are (in words)
143  *	2*length(file0) + length(file1) + 3*(number of k-candidates installed),
144  *	typically about 6n words for files of length n.
145  */
146 
147 struct cand {
148 	int	x;
149 	int	y;
150 	int	pred;
151 };
152 
153 static struct line {
154 	int	serial;
155 	int	value;
156 } *file[2];
157 
158 /*
159  * The following struct is used to record change information when
160  * doing a "context" or "unified" diff.  (see routine "change" to
161  * understand the highly mnemonic field names)
162  */
163 struct context_vec {
164 	int	a;		/* start line in old file */
165 	int	b;		/* end line in old file */
166 	int	c;		/* start line in new file */
167 	int	d;		/* end line in new file */
168 };
169 
170 enum readhash { RH_BINARY, RH_OK, RH_EOF };
171 
172 #define MIN_PAD		1
173 static FILE	*opentemp(const char *);
174 static void	 output(char *, FILE *, char *, FILE *, int);
175 static void	 check(FILE *, FILE *, int);
176 static void	 range(int, int, const char *);
177 static void	 uni_range(int, int);
178 static void	 dump_context_vec(FILE *, FILE *, int);
179 static void	 dump_unified_vec(FILE *, FILE *, int);
180 static bool	 prepare(int, FILE *, size_t, int);
181 static void	 prune(void);
182 static void	 equiv(struct line *, int, struct line *, int, int *);
183 static void	 unravel(int);
184 static void	 unsort(struct line *, int, int *);
185 static void	 change(char *, FILE *, char *, FILE *, int, int, int, int, int *);
186 static void	 sort(struct line *, int);
187 static void	 print_header(const char *, const char *);
188 static void	 print_space(int, int, int);
189 static bool	 ignoreline_pattern(char *);
190 static bool	 ignoreline(char *, bool);
191 static int	 asciifile(FILE *);
192 static int	 fetch(long *, int, int, FILE *, int, int, int);
193 static int	 newcand(int, int, int);
194 static int	 search(int *, int, int);
195 static int	 skipline(FILE *);
196 static int	 stone(int *, int, int *, int *, int);
197 static enum readhash readhash(FILE *, int, unsigned *);
198 static int	 files_differ(FILE *, FILE *, int);
199 static char	*match_function(const long *, int, FILE *);
200 static char	*preadline(int, size_t, off_t);
201 
202 static int	 *J;			/* will be overlaid on class */
203 static int	 *class;		/* will be overlaid on file[0] */
204 static int	 *klist;		/* will be overlaid on file[0] after class */
205 static int	 *member;		/* will be overlaid on file[1] */
206 static int	 clen;
207 static int	 inifdef;		/* whether or not we are in a #ifdef block */
208 static int	 len[2];
209 static int	 pref, suff;	/* length of prefix and suffix */
210 static int	 slen[2];
211 static int	 anychange;
212 static int	 hw, padding;	/* half width and padding */
213 static int	 edoffset;
214 static long	*ixnew;		/* will be overlaid on file[1] */
215 static long	*ixold;		/* will be overlaid on klist */
216 static struct cand *clist;	/* merely a free storage pot for candidates */
217 static int	 clistlen;		/* the length of clist */
218 static struct line *sfile[2];	/* shortened by pruning common prefix/suffix */
219 static int	(*chrtran)(int);	/* translation table for case-folding */
220 static struct context_vec *context_vec_start;
221 static struct context_vec *context_vec_end;
222 static struct context_vec *context_vec_ptr;
223 
224 #define FUNCTION_CONTEXT_SIZE	55
225 static char lastbuf[FUNCTION_CONTEXT_SIZE];
226 static int lastline;
227 static int lastmatchline;
228 
229 static int
230 clow2low(int c)
231 {
232 
233 	return (c);
234 }
235 
236 static int
237 cup2low(int c)
238 {
239 
240 	return (tolower(c));
241 }
242 
243 int
244 diffreg(char *file1, char *file2, int flags, int capsicum)
245 {
246 	FILE *f1, *f2;
247 	int i, rval;
248 	struct pr *pr = NULL;
249 	cap_rights_t rights_ro;
250 
251 	f1 = f2 = NULL;
252 	rval = D_SAME;
253 	anychange = 0;
254 	lastline = 0;
255 	lastmatchline = 0;
256 
257 	 /*
258 	  * hw excludes padding and make sure when -t is not used,
259 	  * the second column always starts from the closest tab stop
260 	  */
261 	if (diff_format == D_SIDEBYSIDE) {
262 		hw = width >> 1;
263 		padding = tabsize - (hw % tabsize);
264 		if ((flags & D_EXPANDTABS) != 0 || (padding % tabsize == 0))
265 			padding = MIN_PAD;
266 
267 		hw = (width >> 1) -
268 		    ((padding == MIN_PAD) ? (padding << 1) : padding) - 1;
269 	}
270 
271 
272 	if (flags & D_IGNORECASE)
273 		chrtran = cup2low;
274 	else
275 		chrtran = clow2low;
276 	if (S_ISDIR(stb1.st_mode) != S_ISDIR(stb2.st_mode))
277 		return (S_ISDIR(stb1.st_mode) ? D_MISMATCH1 : D_MISMATCH2);
278 	if (strcmp(file1, "-") == 0 && strcmp(file2, "-") == 0)
279 		goto closem;
280 
281 	if (flags & D_EMPTY1)
282 		f1 = fopen(_PATH_DEVNULL, "r");
283 	else {
284 		if (!S_ISREG(stb1.st_mode)) {
285 			if ((f1 = opentemp(file1)) == NULL ||
286 			    fstat(fileno(f1), &stb1) == -1) {
287 				warn("%s", file1);
288 				rval = D_ERROR;
289 				status |= 2;
290 				goto closem;
291 			}
292 		} else if (strcmp(file1, "-") == 0)
293 			f1 = stdin;
294 		else
295 			f1 = fopen(file1, "r");
296 	}
297 	if (f1 == NULL) {
298 		warn("%s", file1);
299 		rval = D_ERROR;
300 		status |= 2;
301 		goto closem;
302 	}
303 
304 	if (flags & D_EMPTY2)
305 		f2 = fopen(_PATH_DEVNULL, "r");
306 	else {
307 		if (!S_ISREG(stb2.st_mode)) {
308 			if ((f2 = opentemp(file2)) == NULL ||
309 			    fstat(fileno(f2), &stb2) == -1) {
310 				warn("%s", file2);
311 				rval = D_ERROR;
312 				status |= 2;
313 				goto closem;
314 			}
315 		} else if (strcmp(file2, "-") == 0)
316 			f2 = stdin;
317 		else
318 			f2 = fopen(file2, "r");
319 	}
320 	if (f2 == NULL) {
321 		warn("%s", file2);
322 		rval = D_ERROR;
323 		status |= 2;
324 		goto closem;
325 	}
326 
327 	if (lflag)
328 		pr = start_pr(file1, file2);
329 
330 	if (capsicum) {
331 		cap_rights_init(&rights_ro, CAP_READ, CAP_FSTAT, CAP_SEEK);
332 		if (caph_rights_limit(fileno(f1), &rights_ro) < 0)
333 			err(2, "unable to limit rights on: %s", file1);
334 		if (caph_rights_limit(fileno(f2), &rights_ro) < 0)
335 			err(2, "unable to limit rights on: %s", file2);
336 		if (fileno(f1) == STDIN_FILENO || fileno(f2) == STDIN_FILENO) {
337 			/* stdin has already been limited */
338 			if (caph_limit_stderr() == -1)
339 				err(2, "unable to limit stderr");
340 			if (caph_limit_stdout() == -1)
341 				err(2, "unable to limit stdout");
342 		} else if (caph_limit_stdio() == -1)
343 				err(2, "unable to limit stdio");
344 
345 		caph_cache_catpages();
346 		caph_cache_tzdata();
347 		if (caph_enter() < 0)
348 			err(2, "unable to enter capability mode");
349 	}
350 
351 	switch (files_differ(f1, f2, flags)) {
352 	case 0:
353 		goto closem;
354 	case 1:
355 		break;
356 	default:
357 		/* error */
358 		rval = D_ERROR;
359 		status |= 2;
360 		goto closem;
361 	}
362 
363 	if (diff_format == D_BRIEF && ignore_pats == NULL &&
364 	    (flags & (D_FOLDBLANKS|D_IGNOREBLANKS|D_IGNORECASE|D_STRIPCR)) == 0)
365 	{
366 		rval = D_DIFFER;
367 		status |= 1;
368 		goto closem;
369 	}
370 	if ((flags & D_FORCEASCII) != 0) {
371 		(void)prepare(0, f1, stb1.st_size, flags);
372 		(void)prepare(1, f2, stb2.st_size, flags);
373 	} else if (!asciifile(f1) || !asciifile(f2) ||
374 		    !prepare(0, f1, stb1.st_size, flags) ||
375 		    !prepare(1, f2, stb2.st_size, flags)) {
376 		rval = D_BINARY;
377 		status |= 1;
378 		goto closem;
379 	}
380 
381 	prune();
382 	sort(sfile[0], slen[0]);
383 	sort(sfile[1], slen[1]);
384 
385 	member = (int *)file[1];
386 	equiv(sfile[0], slen[0], sfile[1], slen[1], member);
387 	member = xreallocarray(member, slen[1] + 2, sizeof(*member));
388 
389 	class = (int *)file[0];
390 	unsort(sfile[0], slen[0], class);
391 	class = xreallocarray(class, slen[0] + 2, sizeof(*class));
392 
393 	klist = xcalloc(slen[0] + 2, sizeof(*klist));
394 	clen = 0;
395 	clistlen = 100;
396 	clist = xcalloc(clistlen, sizeof(*clist));
397 	i = stone(class, slen[0], member, klist, flags);
398 	free(member);
399 	free(class);
400 
401 	J = xreallocarray(J, len[0] + 2, sizeof(*J));
402 	unravel(klist[i]);
403 	free(clist);
404 	free(klist);
405 
406 	ixold = xreallocarray(ixold, len[0] + 2, sizeof(*ixold));
407 	ixnew = xreallocarray(ixnew, len[1] + 2, sizeof(*ixnew));
408 	check(f1, f2, flags);
409 	output(file1, f1, file2, f2, flags);
410 
411 closem:
412 	if (pr != NULL)
413 		stop_pr(pr);
414 	if (anychange) {
415 		status |= 1;
416 		if (rval == D_SAME)
417 			rval = D_DIFFER;
418 	}
419 	if (f1 != NULL)
420 		fclose(f1);
421 	if (f2 != NULL)
422 		fclose(f2);
423 
424 	return (rval);
425 }
426 
427 /*
428  * Check to see if the given files differ.
429  * Returns 0 if they are the same, 1 if different, and -1 on error.
430  * XXX - could use code from cmp(1) [faster]
431  */
432 static int
433 files_differ(FILE *f1, FILE *f2, int flags)
434 {
435 	char buf1[BUFSIZ], buf2[BUFSIZ];
436 	size_t i, j;
437 
438 	if ((flags & (D_EMPTY1|D_EMPTY2)) || stb1.st_size != stb2.st_size ||
439 	    (stb1.st_mode & S_IFMT) != (stb2.st_mode & S_IFMT))
440 		return (1);
441 
442 	if (stb1.st_dev == stb2.st_dev && stb1.st_ino == stb2.st_ino)
443 		return (0);
444 
445 	for (;;) {
446 		i = fread(buf1, 1, sizeof(buf1), f1);
447 		j = fread(buf2, 1, sizeof(buf2), f2);
448 		if ((!i && ferror(f1)) || (!j && ferror(f2)))
449 			return (-1);
450 		if (i != j)
451 			return (1);
452 		if (i == 0)
453 			return (0);
454 		if (memcmp(buf1, buf2, i) != 0)
455 			return (1);
456 	}
457 }
458 
459 static FILE *
460 opentemp(const char *f)
461 {
462 	char buf[BUFSIZ], tempfile[PATH_MAX];
463 	ssize_t nread;
464 	int ifd, ofd;
465 
466 	if (strcmp(f, "-") == 0)
467 		ifd = STDIN_FILENO;
468 	else if ((ifd = open(f, O_RDONLY, 0644)) == -1)
469 		return (NULL);
470 
471 	(void)strlcpy(tempfile, _PATH_TMP "/diff.XXXXXXXX", sizeof(tempfile));
472 
473 	if ((ofd = mkstemp(tempfile)) == -1) {
474 		close(ifd);
475 		return (NULL);
476 	}
477 	unlink(tempfile);
478 	while ((nread = read(ifd, buf, BUFSIZ)) > 0) {
479 		if (write(ofd, buf, nread) != nread) {
480 			close(ifd);
481 			close(ofd);
482 			return (NULL);
483 		}
484 	}
485 	close(ifd);
486 	lseek(ofd, (off_t)0, SEEK_SET);
487 	return (fdopen(ofd, "r"));
488 }
489 
490 static bool
491 prepare(int i, FILE *fd, size_t filesize, int flags)
492 {
493 	struct line *p;
494 	unsigned h;
495 	size_t sz, j = 0;
496 	enum readhash r;
497 
498 	rewind(fd);
499 
500 	sz = MIN(filesize, SIZE_MAX) / 25;
501 	if (sz < 100)
502 		sz = 100;
503 
504 	p = xcalloc(sz + 3, sizeof(*p));
505 	while ((r = readhash(fd, flags, &h)) != RH_EOF)
506 		switch (r) {
507 		case RH_EOF: /* otherwise clang complains */
508 		case RH_BINARY:
509 			return (false);
510 		case RH_OK:
511 			if (j == sz) {
512 				sz = sz * 3 / 2;
513 				p = xreallocarray(p, sz + 3, sizeof(*p));
514 			}
515 			p[++j].value = h;
516 		}
517 
518 	len[i] = j;
519 	file[i] = p;
520 
521 	return (true);
522 }
523 
524 static void
525 prune(void)
526 {
527 	int i, j;
528 
529 	for (pref = 0; pref < len[0] && pref < len[1] &&
530 	    file[0][pref + 1].value == file[1][pref + 1].value;
531 	    pref++)
532 		;
533 	for (suff = 0; suff < len[0] - pref && suff < len[1] - pref &&
534 	    file[0][len[0] - suff].value == file[1][len[1] - suff].value;
535 	    suff++)
536 		;
537 	for (j = 0; j < 2; j++) {
538 		sfile[j] = file[j] + pref;
539 		slen[j] = len[j] - pref - suff;
540 		for (i = 0; i <= slen[j]; i++)
541 			sfile[j][i].serial = i;
542 	}
543 }
544 
545 static void
546 equiv(struct line *a, int n, struct line *b, int m, int *c)
547 {
548 	int i, j;
549 
550 	i = j = 1;
551 	while (i <= n && j <= m) {
552 		if (a[i].value < b[j].value)
553 			a[i++].value = 0;
554 		else if (a[i].value == b[j].value)
555 			a[i++].value = j;
556 		else
557 			j++;
558 	}
559 	while (i <= n)
560 		a[i++].value = 0;
561 	b[m + 1].value = 0;
562 	j = 0;
563 	while (++j <= m) {
564 		c[j] = -b[j].serial;
565 		while (b[j + 1].value == b[j].value) {
566 			j++;
567 			c[j] = b[j].serial;
568 		}
569 	}
570 	c[j] = -1;
571 }
572 
573 static int
574 stone(int *a, int n, int *b, int *c, int flags)
575 {
576 	int i, k, y, j, l;
577 	int oldc, tc, oldl, sq;
578 	unsigned numtries, bound;
579 
580 	if (flags & D_MINIMAL)
581 		bound = UINT_MAX;
582 	else {
583 		sq = sqrt(n);
584 		bound = MAX(256, sq);
585 	}
586 
587 	k = 0;
588 	c[0] = newcand(0, 0, 0);
589 	for (i = 1; i <= n; i++) {
590 		j = a[i];
591 		if (j == 0)
592 			continue;
593 		y = -b[j];
594 		oldl = 0;
595 		oldc = c[0];
596 		numtries = 0;
597 		do {
598 			if (y <= clist[oldc].y)
599 				continue;
600 			l = search(c, k, y);
601 			if (l != oldl + 1)
602 				oldc = c[l - 1];
603 			if (l <= k) {
604 				if (clist[c[l]].y <= y)
605 					continue;
606 				tc = c[l];
607 				c[l] = newcand(i, y, oldc);
608 				oldc = tc;
609 				oldl = l;
610 				numtries++;
611 			} else {
612 				c[l] = newcand(i, y, oldc);
613 				k++;
614 				break;
615 			}
616 		} while ((y = b[++j]) > 0 && numtries < bound);
617 	}
618 	return (k);
619 }
620 
621 static int
622 newcand(int x, int y, int pred)
623 {
624 	struct cand *q;
625 
626 	if (clen == clistlen) {
627 		clistlen = clistlen * 11 / 10;
628 		clist = xreallocarray(clist, clistlen, sizeof(*clist));
629 	}
630 	q = clist + clen;
631 	q->x = x;
632 	q->y = y;
633 	q->pred = pred;
634 	return (clen++);
635 }
636 
637 static int
638 search(int *c, int k, int y)
639 {
640 	int i, j, l, t;
641 
642 	if (clist[c[k]].y < y)	/* quick look for typical case */
643 		return (k + 1);
644 	i = 0;
645 	j = k + 1;
646 	for (;;) {
647 		l = (i + j) / 2;
648 		if (l <= i)
649 			break;
650 		t = clist[c[l]].y;
651 		if (t > y)
652 			j = l;
653 		else if (t < y)
654 			i = l;
655 		else
656 			return (l);
657 	}
658 	return (l + 1);
659 }
660 
661 static void
662 unravel(int p)
663 {
664 	struct cand *q;
665 	int i;
666 
667 	for (i = 0; i <= len[0]; i++)
668 		J[i] = i <= pref ? i :
669 		    i > len[0] - suff ? i + len[1] - len[0] : 0;
670 	for (q = clist + p; q->y != 0; q = clist + q->pred)
671 		J[q->x + pref] = q->y + pref;
672 }
673 
674 /*
675  * Check does double duty:
676  *  1. ferret out any fortuitous correspondences due to confounding by
677  *     hashing (which result in "jackpot")
678  *  2. collect random access indexes to the two files
679  */
680 static void
681 check(FILE *f1, FILE *f2, int flags)
682 {
683 	int i, j, /* jackpot, */ c, d;
684 	long ctold, ctnew;
685 
686 	rewind(f1);
687 	rewind(f2);
688 	j = 1;
689 	ixold[0] = ixnew[0] = 0;
690 	/* jackpot = 0; */
691 	ctold = ctnew = 0;
692 	for (i = 1; i <= len[0]; i++) {
693 		if (J[i] == 0) {
694 			ixold[i] = ctold += skipline(f1);
695 			continue;
696 		}
697 		while (j < J[i]) {
698 			ixnew[j] = ctnew += skipline(f2);
699 			j++;
700 		}
701 		if (flags & (D_FOLDBLANKS | D_IGNOREBLANKS | D_IGNORECASE | D_STRIPCR)) {
702 			for (;;) {
703 				c = getc(f1);
704 				d = getc(f2);
705 				/*
706 				 * GNU diff ignores a missing newline
707 				 * in one file for -b or -w.
708 				 */
709 				if (flags & (D_FOLDBLANKS | D_IGNOREBLANKS)) {
710 					if (c == EOF && d == '\n') {
711 						ctnew++;
712 						break;
713 					} else if (c == '\n' && d == EOF) {
714 						ctold++;
715 						break;
716 					}
717 				}
718 				ctold++;
719 				ctnew++;
720 				if (flags & D_STRIPCR && (c == '\r' || d == '\r')) {
721 					if (c == '\r') {
722 						if ((c = getc(f1)) == '\n') {
723 							ctold++;
724 						} else {
725 							ungetc(c, f1);
726 						}
727 					}
728 					if (d == '\r') {
729 						if ((d = getc(f2)) == '\n') {
730 							ctnew++;
731 						} else {
732 							ungetc(d, f2);
733 						}
734 					}
735 					break;
736 				}
737 				if ((flags & D_FOLDBLANKS) && isspace(c) &&
738 				    isspace(d)) {
739 					do {
740 						if (c == '\n')
741 							break;
742 						ctold++;
743 					} while (isspace(c = getc(f1)));
744 					do {
745 						if (d == '\n')
746 							break;
747 						ctnew++;
748 					} while (isspace(d = getc(f2)));
749 				} else if (flags & D_IGNOREBLANKS) {
750 					while (isspace(c) && c != '\n') {
751 						c = getc(f1);
752 						ctold++;
753 					}
754 					while (isspace(d) && d != '\n') {
755 						d = getc(f2);
756 						ctnew++;
757 					}
758 				}
759 				if (chrtran(c) != chrtran(d)) {
760 					/* jackpot++; */
761 					J[i] = 0;
762 					if (c != '\n' && c != EOF)
763 						ctold += skipline(f1);
764 					if (d != '\n' && c != EOF)
765 						ctnew += skipline(f2);
766 					break;
767 				}
768 				if (c == '\n' || c == EOF)
769 					break;
770 			}
771 		} else {
772 			for (;;) {
773 				ctold++;
774 				ctnew++;
775 				if ((c = getc(f1)) != (d = getc(f2))) {
776 					/* jackpot++; */
777 					J[i] = 0;
778 					if (c != '\n' && c != EOF)
779 						ctold += skipline(f1);
780 					if (d != '\n' && c != EOF)
781 						ctnew += skipline(f2);
782 					break;
783 				}
784 				if (c == '\n' || c == EOF)
785 					break;
786 			}
787 		}
788 		ixold[i] = ctold;
789 		ixnew[j] = ctnew;
790 		j++;
791 	}
792 	for (; j <= len[1]; j++) {
793 		ixnew[j] = ctnew += skipline(f2);
794 	}
795 	/*
796 	 * if (jackpot)
797 	 *	fprintf(stderr, "jackpot\n");
798 	 */
799 }
800 
801 /* shellsort CACM #201 */
802 static void
803 sort(struct line *a, int n)
804 {
805 	struct line *ai, *aim, w;
806 	int j, m = 0, k;
807 
808 	if (n == 0)
809 		return;
810 	for (j = 1; j <= n; j *= 2)
811 		m = 2 * j - 1;
812 	for (m /= 2; m != 0; m /= 2) {
813 		k = n - m;
814 		for (j = 1; j <= k; j++) {
815 			for (ai = &a[j]; ai > a; ai -= m) {
816 				aim = &ai[m];
817 				if (aim < ai)
818 					break;	/* wraparound */
819 				if (aim->value > ai[0].value ||
820 				    (aim->value == ai[0].value &&
821 					aim->serial > ai[0].serial))
822 					break;
823 				w.value = ai[0].value;
824 				ai[0].value = aim->value;
825 				aim->value = w.value;
826 				w.serial = ai[0].serial;
827 				ai[0].serial = aim->serial;
828 				aim->serial = w.serial;
829 			}
830 		}
831 	}
832 }
833 
834 static void
835 unsort(struct line *f, int l, int *b)
836 {
837 	int *a, i;
838 
839 	a = xcalloc(l + 1, sizeof(*a));
840 	for (i = 1; i <= l; i++)
841 		a[f[i].serial] = f[i].value;
842 	for (i = 1; i <= l; i++)
843 		b[i] = a[i];
844 	free(a);
845 }
846 
847 static int
848 skipline(FILE *f)
849 {
850 	int i, c;
851 
852 	for (i = 1; (c = getc(f)) != '\n' && c != EOF; i++)
853 		continue;
854 	return (i);
855 }
856 
857 static void
858 output(char *file1, FILE *f1, char *file2, FILE *f2, int flags)
859 {
860 	int i, j, m, i0, i1, j0, j1, nc;
861 
862 	rewind(f1);
863 	rewind(f2);
864 	m = len[0];
865 	J[0] = 0;
866 	J[m + 1] = len[1] + 1;
867 	if (diff_format != D_EDIT) {
868 		for (i0 = 1; i0 <= m; i0 = i1 + 1) {
869 			while (i0 <= m && J[i0] == J[i0 - 1] + 1) {
870 				if (diff_format == D_SIDEBYSIDE && suppress_common != 1) {
871 					nc = fetch(ixold, i0, i0, f1, '\0', 1, flags);
872 					print_space(nc, (hw - nc) + (padding << 1) + 1, flags);
873 					fetch(ixnew, J[i0], J[i0], f2, '\0', 0, flags);
874 					printf("\n");
875 				}
876 				i0++;
877 			}
878 			j0 = J[i0 - 1] + 1;
879 			i1 = i0 - 1;
880 			while (i1 < m && J[i1 + 1] == 0)
881 				i1++;
882 			j1 = J[i1 + 1] - 1;
883 			J[i1] = j1;
884 
885 			/*
886 			 * When using side-by-side, lines from both of the files are
887 			 * printed. The algorithm used by diff(1) identifies the ranges
888 			 * in which two files differ.
889 			 * See the change() function below.
890 			 * The for loop below consumes the shorter range, whereas one of
891 			 * the while loops deals with the longer one.
892 			 */
893 			if (diff_format == D_SIDEBYSIDE) {
894 				for (i = i0, j = j0; i <= i1 && j <= j1; i++, j++)
895 					change(file1, f1, file2, f2, i, i, j, j, &flags);
896 
897 				while (i <= i1) {
898 					change(file1, f1, file2, f2, i, i, j + 1, j, &flags);
899 					i++;
900 				}
901 
902 				while (j <= j1) {
903 					change(file1, f1, file2, f2, i + 1, i, j, j, &flags);
904 					j++;
905 				}
906 			} else
907 				change(file1, f1, file2, f2, i0, i1, j0, j1, &flags);
908 		}
909 	} else {
910 		for (i0 = m; i0 >= 1; i0 = i1 - 1) {
911 			while (i0 >= 1 && J[i0] == J[i0 + 1] - 1 && J[i0] != 0)
912 				i0--;
913 			j0 = J[i0 + 1] - 1;
914 			i1 = i0 + 1;
915 			while (i1 > 1 && J[i1 - 1] == 0)
916 				i1--;
917 			j1 = J[i1 - 1] + 1;
918 			J[i1] = j1;
919 			change(file1, f1, file2, f2, i1, i0, j1, j0, &flags);
920 		}
921 	}
922 	if (m == 0)
923 		change(file1, f1, file2, f2, 1, 0, 1, len[1], &flags);
924 	if (diff_format == D_IFDEF || diff_format == D_GFORMAT) {
925 		for (;;) {
926 #define	c i0
927 			if ((c = getc(f1)) == EOF)
928 				return;
929 			printf("%c", c);
930 		}
931 #undef c
932 	}
933 	if (anychange != 0) {
934 		if (diff_format == D_CONTEXT)
935 			dump_context_vec(f1, f2, flags);
936 		else if (diff_format == D_UNIFIED)
937 			dump_unified_vec(f1, f2, flags);
938 	}
939 }
940 
941 static void
942 range(int a, int b, const char *separator)
943 {
944 	printf("%d", a > b ? b : a);
945 	if (a < b)
946 		printf("%s%d", separator, b);
947 }
948 
949 static void
950 uni_range(int a, int b)
951 {
952 	if (a < b)
953 		printf("%d,%d", a, b - a + 1);
954 	else if (a == b)
955 		printf("%d", b);
956 	else
957 		printf("%d,0", b);
958 }
959 
960 static char *
961 preadline(int fd, size_t rlen, off_t off)
962 {
963 	char *line;
964 	ssize_t nr;
965 
966 	line = xmalloc(rlen + 1);
967 	if ((nr = pread(fd, line, rlen, off)) == -1)
968 		err(2, "preadline");
969 	if (nr > 0 && line[nr-1] == '\n')
970 		nr--;
971 	line[nr] = '\0';
972 	return (line);
973 }
974 
975 static bool
976 ignoreline_pattern(char *line)
977 {
978 	int ret;
979 
980 	ret = regexec(&ignore_re, line, 0, NULL, 0);
981 	return (ret == 0);	/* if it matched, it should be ignored. */
982 }
983 
984 static bool
985 ignoreline(char *line, bool skip_blanks)
986 {
987 
988 	if (skip_blanks && *line == '\0')
989 		return (true);
990 	if (ignore_pats != NULL && ignoreline_pattern(line))
991 		return (true);
992 	return (false);
993 }
994 
995 /*
996  * Indicate that there is a difference between lines a and b of the from file
997  * to get to lines c to d of the to file.  If a is greater then b then there
998  * are no lines in the from file involved and this means that there were
999  * lines appended (beginning at b).  If c is greater than d then there are
1000  * lines missing from the to file.
1001  */
1002 static void
1003 change(char *file1, FILE *f1, char *file2, FILE *f2, int a, int b, int c, int d,
1004     int *pflags)
1005 {
1006 	static size_t max_context = 64;
1007 	long curpos;
1008 	int i, nc;
1009 	const char *walk;
1010 	bool skip_blanks, ignore;
1011 
1012 	skip_blanks = (*pflags & D_SKIPBLANKLINES);
1013 restart:
1014 	if ((diff_format != D_IFDEF || diff_format == D_GFORMAT) &&
1015 	    a > b && c > d)
1016 		return;
1017 	if (ignore_pats != NULL || skip_blanks) {
1018 		char *line;
1019 		/*
1020 		 * All lines in the change, insert, or delete must match an ignore
1021 		 * pattern for the change to be ignored.
1022 		 */
1023 		if (a <= b) {		/* Changes and deletes. */
1024 			for (i = a; i <= b; i++) {
1025 				line = preadline(fileno(f1),
1026 				    ixold[i] - ixold[i - 1], ixold[i - 1]);
1027 				ignore = ignoreline(line, skip_blanks);
1028 				free(line);
1029 				if (!ignore)
1030 					goto proceed;
1031 			}
1032 		}
1033 		if (a > b || c <= d) {	/* Changes and inserts. */
1034 			for (i = c; i <= d; i++) {
1035 				line = preadline(fileno(f2),
1036 				    ixnew[i] - ixnew[i - 1], ixnew[i - 1]);
1037 				ignore = ignoreline(line, skip_blanks);
1038 				free(line);
1039 				if (!ignore)
1040 					goto proceed;
1041 			}
1042 		}
1043 		return;
1044 	}
1045 proceed:
1046 	if (*pflags & D_HEADER && diff_format != D_BRIEF) {
1047 		printf("%s %s %s\n", diffargs, file1, file2);
1048 		*pflags &= ~D_HEADER;
1049 	}
1050 	if (diff_format == D_CONTEXT || diff_format == D_UNIFIED) {
1051 		/*
1052 		 * Allocate change records as needed.
1053 		 */
1054 		if (context_vec_start == NULL ||
1055 		    context_vec_ptr == context_vec_end - 1) {
1056 			ptrdiff_t offset = -1;
1057 
1058 			if (context_vec_start != NULL)
1059 				offset = context_vec_ptr - context_vec_start;
1060 			max_context <<= 1;
1061 			context_vec_start = xreallocarray(context_vec_start,
1062 			    max_context, sizeof(*context_vec_start));
1063 			context_vec_end = context_vec_start + max_context;
1064 			context_vec_ptr = context_vec_start + offset;
1065 		}
1066 		if (anychange == 0) {
1067 			/*
1068 			 * Print the context/unidiff header first time through.
1069 			 */
1070 			print_header(file1, file2);
1071 			anychange = 1;
1072 		} else if (a > context_vec_ptr->b + (2 * diff_context) + 1 &&
1073 		    c > context_vec_ptr->d + (2 * diff_context) + 1) {
1074 			/*
1075 			 * If this change is more than 'diff_context' lines from the
1076 			 * previous change, dump the record and reset it.
1077 			 */
1078 			if (diff_format == D_CONTEXT)
1079 				dump_context_vec(f1, f2, *pflags);
1080 			else
1081 				dump_unified_vec(f1, f2, *pflags);
1082 		}
1083 		context_vec_ptr++;
1084 		context_vec_ptr->a = a;
1085 		context_vec_ptr->b = b;
1086 		context_vec_ptr->c = c;
1087 		context_vec_ptr->d = d;
1088 		return;
1089 	}
1090 	if (anychange == 0)
1091 		anychange = 1;
1092 	switch (diff_format) {
1093 	case D_BRIEF:
1094 		return;
1095 	case D_NORMAL:
1096 	case D_EDIT:
1097 		range(a, b, ",");
1098 		printf("%c", a > b ? 'a' : c > d ? 'd' : 'c');
1099 		if (diff_format == D_NORMAL)
1100 			range(c, d, ",");
1101 		printf("\n");
1102 		break;
1103 	case D_REVERSE:
1104 		printf("%c", a > b ? 'a' : c > d ? 'd' : 'c');
1105 		range(a, b, " ");
1106 		printf("\n");
1107 		break;
1108 	case D_NREVERSE:
1109 		if (a > b)
1110 			printf("a%d %d\n", b, d - c + 1);
1111 		else {
1112 			printf("d%d %d\n", a, b - a + 1);
1113 			if (!(c > d))
1114 				/* add changed lines */
1115 				printf("a%d %d\n", b, d - c + 1);
1116 		}
1117 		break;
1118 	}
1119 	if (diff_format == D_GFORMAT) {
1120 		curpos = ftell(f1);
1121 		/* print through if append (a>b), else to (nb: 0 vs 1 orig) */
1122 		nc = ixold[a > b ? b : a - 1] - curpos;
1123 		for (i = 0; i < nc; i++)
1124 			printf("%c", getc(f1));
1125 		for (walk = group_format; *walk != '\0'; walk++) {
1126 			if (*walk == '%') {
1127 				walk++;
1128 				switch (*walk) {
1129 				case '<':
1130 					fetch(ixold, a, b, f1, '<', 1, *pflags);
1131 					break;
1132 				case '>':
1133 					fetch(ixnew, c, d, f2, '>', 0, *pflags);
1134 					break;
1135 				default:
1136 					printf("%%%c", *walk);
1137 					break;
1138 				}
1139 				continue;
1140 			}
1141 			printf("%c", *walk);
1142 		}
1143 	}
1144 	if (diff_format == D_SIDEBYSIDE) {
1145 		if (color && a > b)
1146 			printf("\033[%sm", add_code);
1147 		else if (color && c > d)
1148 			printf("\033[%sm", del_code);
1149 		if (a > b) {
1150 			print_space(0, hw + padding , *pflags);
1151 		} else {
1152 			nc = fetch(ixold, a, b, f1, '\0', 1, *pflags);
1153 			print_space(nc, hw - nc + padding, *pflags);
1154 		}
1155 		if (color && a > b)
1156 			printf("\033[%sm", add_code);
1157 		else if (color && c > d)
1158 			printf("\033[%sm", del_code);
1159 		printf("%c", (a > b) ? '>' : ((c > d) ? '<' : '|'));
1160 		if (color && c > d)
1161 			printf("\033[m");
1162 		print_space(hw + padding + 1 , padding, *pflags);
1163 		fetch(ixnew, c, d, f2, '\0', 0, *pflags);
1164 		printf("\n");
1165 	}
1166 	if (diff_format == D_NORMAL || diff_format == D_IFDEF) {
1167 		fetch(ixold, a, b, f1, '<', 1, *pflags);
1168 		if (a <= b && c <= d && diff_format == D_NORMAL)
1169 			printf("---\n");
1170 	}
1171 	if (diff_format != D_GFORMAT && diff_format != D_SIDEBYSIDE)
1172 		fetch(ixnew, c, d, f2, diff_format == D_NORMAL ? '>' : '\0', 0, *pflags);
1173 	if (edoffset != 0 && diff_format == D_EDIT) {
1174 		/*
1175 		 * A non-zero edoffset value for D_EDIT indicates that the last line
1176 		 * printed was a bare dot (".") that has been escaped as ".." to
1177 		 * prevent ed(1) from misinterpreting it.  We have to add a
1178 		 * substitute command to change this back and restart where we left
1179 		 * off.
1180 		 */
1181 		printf(".\n");
1182 		printf("%ds/.//\n", a + edoffset - 1);
1183 		b = a + edoffset - 1;
1184 		a = b + 1;
1185 		c += edoffset;
1186 		goto restart;
1187 	}
1188 	if ((diff_format == D_EDIT || diff_format == D_REVERSE) && c <= d)
1189 		printf(".\n");
1190 	if (inifdef) {
1191 		printf("#endif /* %s */\n", ifdefname);
1192 		inifdef = 0;
1193 	}
1194 }
1195 
1196 static int
1197 fetch(long *f, int a, int b, FILE *lb, int ch, int oldfile, int flags)
1198 {
1199 	int i, j, c, lastc, col, nc, newcol;
1200 
1201 	edoffset = 0;
1202 	nc = 0;
1203 	/*
1204 	 * When doing #ifdef's, copy down to current line
1205 	 * if this is the first file, so that stuff makes it to output.
1206 	 */
1207 	if ((diff_format == D_IFDEF) && oldfile) {
1208 		long curpos = ftell(lb);
1209 		/* print through if append (a>b), else to (nb: 0 vs 1 orig) */
1210 		nc = f[a > b ? b : a - 1] - curpos;
1211 		for (i = 0; i < nc; i++)
1212 			printf("%c", getc(lb));
1213 	}
1214 	if (a > b)
1215 		return (0);
1216 	if (diff_format == D_IFDEF) {
1217 		if (inifdef) {
1218 			printf("#else /* %s%s */\n",
1219 			    oldfile == 1 ? "!" : "", ifdefname);
1220 		} else {
1221 			if (oldfile)
1222 				printf("#ifndef %s\n", ifdefname);
1223 			else
1224 				printf("#ifdef %s\n", ifdefname);
1225 		}
1226 		inifdef = 1 + oldfile;
1227 	}
1228 	for (i = a; i <= b; i++) {
1229 		fseek(lb, f[i - 1], SEEK_SET);
1230 		nc = f[i] - f[i - 1];
1231 		if (diff_format == D_SIDEBYSIDE && hw < nc)
1232 			nc = hw;
1233 		if (diff_format != D_IFDEF && diff_format != D_GFORMAT &&
1234 		    ch != '\0') {
1235 			if (color && (ch == '>' || ch == '+'))
1236 				printf("\033[%sm", add_code);
1237 			else if (color && (ch == '<' || ch == '-'))
1238 				printf("\033[%sm", del_code);
1239 			printf("%c", ch);
1240 			if (Tflag && (diff_format == D_NORMAL ||
1241 			    diff_format == D_CONTEXT ||
1242 			    diff_format == D_UNIFIED))
1243 				printf("\t");
1244 			else if (diff_format != D_UNIFIED)
1245 				printf(" ");
1246 		}
1247 		col = j = 0;
1248 		lastc = '\0';
1249 		while (j < nc && (hw == 0 || col < hw)) {
1250 			c = getc(lb);
1251 			if (flags & D_STRIPCR && c == '\r') {
1252 				if ((c = getc(lb)) == '\n')
1253 					j++;
1254 				else {
1255 					ungetc(c, lb);
1256 					c = '\r';
1257 				}
1258 			}
1259 			if (c == EOF) {
1260 				if (diff_format == D_EDIT ||
1261 				    diff_format == D_REVERSE ||
1262 				    diff_format == D_NREVERSE)
1263 					warnx("No newline at end of file");
1264 				else
1265 					printf("\n\\ No newline at end of file\n");
1266 				return (col);
1267 			}
1268 			/*
1269 			 * when using --side-by-side, col needs to be increased
1270 			 * in any case to keep the columns aligned
1271 			 */
1272 			if (c == '\t') {
1273 				if (flags & D_EXPANDTABS) {
1274 					newcol = ((col / tabsize) + 1) * tabsize;
1275 					do {
1276 						printf(" ");
1277 					} while (++col < newcol && col < hw);
1278 				} else {
1279 					if (diff_format == D_SIDEBYSIDE) {
1280 						if ((col + tabsize) > hw) {
1281 							printf("%*s", hw - col, "");
1282 							col = hw;
1283 						} else {
1284 							printf("\t");
1285 							col += tabsize - 1;
1286 						}
1287 					} else {
1288 						printf("\t");
1289 						col++;
1290 					}
1291 				}
1292 			} else {
1293 				if (diff_format == D_EDIT && j == 1 && c == '\n' &&
1294 				    lastc == '.') {
1295 					/*
1296 					 * Don't print a bare "." line since that will confuse
1297 					 * ed(1). Print ".." instead and set the, global variable
1298 					 * edoffset to an offset from which to restart. The
1299 					 * caller must check the value of edoffset
1300 					 */
1301 					printf(".\n");
1302 					edoffset = i - a + 1;
1303 					return (edoffset);
1304 				}
1305 				/* when side-by-side, do not print a newline */
1306 				if (diff_format != D_SIDEBYSIDE || c != '\n') {
1307 					if (color && c == '\n')
1308 						printf("\033[m%c", c);
1309 					else
1310 						printf("%c", c);
1311 					col++;
1312 				}
1313 			}
1314 
1315 			j++;
1316 			lastc = c;
1317 		}
1318 	}
1319 	if (color && diff_format == D_SIDEBYSIDE)
1320 		printf("\033[m");
1321 	return (col);
1322 }
1323 
1324 /*
1325  * Hash function taken from Robert Sedgewick, Algorithms in C, 3d ed., p 578.
1326  */
1327 static enum readhash
1328 readhash(FILE *f, int flags, unsigned *hash)
1329 {
1330 	int i, t, space;
1331 	unsigned sum;
1332 
1333 	sum = 1;
1334 	space = 0;
1335 	for (i = 0;;) {
1336 		switch (t = getc(f)) {
1337 		case '\0':
1338 			if ((flags & D_FORCEASCII) == 0)
1339 				return (RH_BINARY);
1340 			goto hashchar;
1341 		case '\r':
1342 			if (flags & D_STRIPCR) {
1343 				t = getc(f);
1344 				if (t == '\n')
1345 					break;
1346 				ungetc(t, f);
1347 			}
1348 			/* FALLTHROUGH */
1349 		case '\t':
1350 		case '\v':
1351 		case '\f':
1352 		case ' ':
1353 			if ((flags & (D_FOLDBLANKS|D_IGNOREBLANKS)) != 0) {
1354 				space++;
1355 				continue;
1356 			}
1357 			/* FALLTHROUGH */
1358 		default:
1359 		hashchar:
1360 			if (space && (flags & D_IGNOREBLANKS) == 0) {
1361 				i++;
1362 				space = 0;
1363 			}
1364 			sum = sum * 127 + chrtran(t);
1365 			i++;
1366 			continue;
1367 		case EOF:
1368 			if (i == 0)
1369 				return (RH_EOF);
1370 			/* FALLTHROUGH */
1371 		case '\n':
1372 			break;
1373 		}
1374 		break;
1375 	}
1376 	*hash = sum;
1377 	return (RH_OK);
1378 }
1379 
1380 static int
1381 asciifile(FILE *f)
1382 {
1383 	unsigned char buf[BUFSIZ];
1384 	size_t cnt;
1385 
1386 	if (f == NULL)
1387 		return (1);
1388 
1389 	rewind(f);
1390 	cnt = fread(buf, 1, sizeof(buf), f);
1391 	return (memchr(buf, '\0', cnt) == NULL);
1392 }
1393 
1394 #define begins_with(s, pre) (strncmp(s, pre, sizeof(pre) - 1) == 0)
1395 
1396 static char *
1397 match_function(const long *f, int pos, FILE *fp)
1398 {
1399 	unsigned char buf[FUNCTION_CONTEXT_SIZE];
1400 	size_t nc;
1401 	int last = lastline;
1402 	const char *state = NULL;
1403 
1404 	lastline = pos;
1405 	for (; pos > last; pos--) {
1406 		fseek(fp, f[pos - 1], SEEK_SET);
1407 		nc = f[pos] - f[pos - 1];
1408 		if (nc >= sizeof(buf))
1409 			nc = sizeof(buf) - 1;
1410 		nc = fread(buf, 1, nc, fp);
1411 		if (nc == 0)
1412 			continue;
1413 		buf[nc] = '\0';
1414 		buf[strcspn(buf, "\n")] = '\0';
1415 		if (most_recent_pat != NULL) {
1416 			int ret = regexec(&most_recent_re, buf, 0, NULL, 0);
1417 
1418 			if (ret != 0)
1419 				continue;
1420 			strlcpy(lastbuf, buf, sizeof(lastbuf));
1421 			lastmatchline = pos;
1422 			return (lastbuf);
1423 		} else if (isalpha(buf[0]) || buf[0] == '_' || buf[0] == '$'
1424 			|| buf[0] == '-' || buf[0] == '+') {
1425 			if (begins_with(buf, "private:")) {
1426 				if (!state)
1427 					state = " (private)";
1428 			} else if (begins_with(buf, "protected:")) {
1429 				if (!state)
1430 					state = " (protected)";
1431 			} else if (begins_with(buf, "public:")) {
1432 				if (!state)
1433 					state = " (public)";
1434 			} else {
1435 				strlcpy(lastbuf, buf, sizeof(lastbuf));
1436 				if (state)
1437 					strlcat(lastbuf, state, sizeof(lastbuf));
1438 				lastmatchline = pos;
1439 				return (lastbuf);
1440 			}
1441 		}
1442 	}
1443 	return (lastmatchline > 0 ? lastbuf : NULL);
1444 }
1445 
1446 /* dump accumulated "context" diff changes */
1447 static void
1448 dump_context_vec(FILE *f1, FILE *f2, int flags)
1449 {
1450 	struct context_vec *cvp = context_vec_start;
1451 	int lowa, upb, lowc, upd, do_output;
1452 	int a, b, c, d;
1453 	char ch, *f;
1454 
1455 	if (context_vec_start > context_vec_ptr)
1456 		return;
1457 
1458 	b = d = 0;		/* gcc */
1459 	lowa = MAX(1, cvp->a - diff_context);
1460 	upb = MIN(len[0], context_vec_ptr->b + diff_context);
1461 	lowc = MAX(1, cvp->c - diff_context);
1462 	upd = MIN(len[1], context_vec_ptr->d + diff_context);
1463 
1464 	printf("***************");
1465 	if (flags & (D_PROTOTYPE | D_MATCHLAST)) {
1466 		f = match_function(ixold, cvp->a - 1, f1);
1467 		if (f != NULL)
1468 			printf(" %s", f);
1469 	}
1470 	printf("\n*** ");
1471 	range(lowa, upb, ",");
1472 	printf(" ****\n");
1473 
1474 	/*
1475 	 * Output changes to the "old" file.  The first loop suppresses
1476 	 * output if there were no changes to the "old" file (we'll see
1477 	 * the "old" lines as context in the "new" list).
1478 	 */
1479 	do_output = 0;
1480 	for (; cvp <= context_vec_ptr; cvp++)
1481 		if (cvp->a <= cvp->b) {
1482 			cvp = context_vec_start;
1483 			do_output++;
1484 			break;
1485 		}
1486 	if (do_output) {
1487 		while (cvp <= context_vec_ptr) {
1488 			a = cvp->a;
1489 			b = cvp->b;
1490 			c = cvp->c;
1491 			d = cvp->d;
1492 
1493 			if (a <= b && c <= d)
1494 				ch = 'c';
1495 			else
1496 				ch = (a <= b) ? 'd' : 'a';
1497 
1498 			if (ch == 'a')
1499 				fetch(ixold, lowa, b, f1, ' ', 0, flags);
1500 			else {
1501 				fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
1502 				fetch(ixold, a, b, f1,
1503 				    ch == 'c' ? '!' : '-', 0, flags);
1504 			}
1505 			lowa = b + 1;
1506 			cvp++;
1507 		}
1508 		fetch(ixold, b + 1, upb, f1, ' ', 0, flags);
1509 	}
1510 	/* output changes to the "new" file */
1511 	printf("--- ");
1512 	range(lowc, upd, ",");
1513 	printf(" ----\n");
1514 
1515 	do_output = 0;
1516 	for (cvp = context_vec_start; cvp <= context_vec_ptr; cvp++)
1517 		if (cvp->c <= cvp->d) {
1518 			cvp = context_vec_start;
1519 			do_output++;
1520 			break;
1521 		}
1522 	if (do_output) {
1523 		while (cvp <= context_vec_ptr) {
1524 			a = cvp->a;
1525 			b = cvp->b;
1526 			c = cvp->c;
1527 			d = cvp->d;
1528 
1529 			if (a <= b && c <= d)
1530 				ch = 'c';
1531 			else
1532 				ch = (a <= b) ? 'd' : 'a';
1533 
1534 			if (ch == 'd')
1535 				fetch(ixnew, lowc, d, f2, ' ', 0, flags);
1536 			else {
1537 				fetch(ixnew, lowc, c - 1, f2, ' ', 0, flags);
1538 				fetch(ixnew, c, d, f2,
1539 				    ch == 'c' ? '!' : '+', 0, flags);
1540 			}
1541 			lowc = d + 1;
1542 			cvp++;
1543 		}
1544 		fetch(ixnew, d + 1, upd, f2, ' ', 0, flags);
1545 	}
1546 	context_vec_ptr = context_vec_start - 1;
1547 }
1548 
1549 /* dump accumulated "unified" diff changes */
1550 static void
1551 dump_unified_vec(FILE *f1, FILE *f2, int flags)
1552 {
1553 	struct context_vec *cvp = context_vec_start;
1554 	int lowa, upb, lowc, upd;
1555 	int a, b, c, d;
1556 	char ch, *f;
1557 
1558 	if (context_vec_start > context_vec_ptr)
1559 		return;
1560 
1561 	b = d = 0;		/* gcc */
1562 	lowa = MAX(1, cvp->a - diff_context);
1563 	upb = MIN(len[0], context_vec_ptr->b + diff_context);
1564 	lowc = MAX(1, cvp->c - diff_context);
1565 	upd = MIN(len[1], context_vec_ptr->d + diff_context);
1566 
1567 	printf("@@ -");
1568 	uni_range(lowa, upb);
1569 	printf(" +");
1570 	uni_range(lowc, upd);
1571 	printf(" @@");
1572 	if (flags & (D_PROTOTYPE | D_MATCHLAST)) {
1573 		f = match_function(ixold, cvp->a - 1, f1);
1574 		if (f != NULL)
1575 			printf(" %s", f);
1576 	}
1577 	printf("\n");
1578 
1579 	/*
1580 	 * Output changes in "unified" diff format--the old and new lines
1581 	 * are printed together.
1582 	 */
1583 	for (; cvp <= context_vec_ptr; cvp++) {
1584 		a = cvp->a;
1585 		b = cvp->b;
1586 		c = cvp->c;
1587 		d = cvp->d;
1588 
1589 		/*
1590 		 * c: both new and old changes
1591 		 * d: only changes in the old file
1592 		 * a: only changes in the new file
1593 		 */
1594 		if (a <= b && c <= d)
1595 			ch = 'c';
1596 		else
1597 			ch = (a <= b) ? 'd' : 'a';
1598 
1599 		switch (ch) {
1600 		case 'c':
1601 			fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
1602 			fetch(ixold, a, b, f1, '-', 0, flags);
1603 			fetch(ixnew, c, d, f2, '+', 0, flags);
1604 			break;
1605 		case 'd':
1606 			fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
1607 			fetch(ixold, a, b, f1, '-', 0, flags);
1608 			break;
1609 		case 'a':
1610 			fetch(ixnew, lowc, c - 1, f2, ' ', 0, flags);
1611 			fetch(ixnew, c, d, f2, '+', 0, flags);
1612 			break;
1613 		}
1614 		lowa = b + 1;
1615 		lowc = d + 1;
1616 	}
1617 	fetch(ixnew, d + 1, upd, f2, ' ', 0, flags);
1618 
1619 	context_vec_ptr = context_vec_start - 1;
1620 }
1621 
1622 static void
1623 print_header(const char *file1, const char *file2)
1624 {
1625 	const char *time_format;
1626 	char buf[256];
1627 	struct tm tm1, tm2, *tm_ptr1, *tm_ptr2;
1628 	int nsec1 = stb1.st_mtim.tv_nsec;
1629 	int nsec2 = stb2.st_mtim.tv_nsec;
1630 
1631 	time_format = "%Y-%m-%d %H:%M:%S";
1632 
1633 	if (cflag)
1634 		time_format = "%c";
1635 	tm_ptr1 = localtime_r(&stb1.st_mtime, &tm1);
1636 	tm_ptr2 = localtime_r(&stb2.st_mtime, &tm2);
1637 	if (label[0] != NULL)
1638 		printf("%s %s\n", diff_format == D_CONTEXT ? "***" : "---",
1639 		    label[0]);
1640 	else {
1641 		strftime(buf, sizeof(buf), time_format, tm_ptr1);
1642 		printf("%s %s\t%s", diff_format == D_CONTEXT ? "***" : "---",
1643 		    file1, buf);
1644 		if (!cflag) {
1645 			strftime(buf, sizeof(buf), "%z", tm_ptr1);
1646 			printf(".%.9d %s", nsec1, buf);
1647 		}
1648 		printf("\n");
1649 	}
1650 	if (label[1] != NULL)
1651 		printf("%s %s\n", diff_format == D_CONTEXT ? "---" : "+++",
1652 		    label[1]);
1653 	else {
1654 		strftime(buf, sizeof(buf), time_format, tm_ptr2);
1655 		printf("%s %s\t%s", diff_format == D_CONTEXT ? "---" : "+++",
1656 		    file2, buf);
1657 		if (!cflag) {
1658 			strftime(buf, sizeof(buf), "%z", tm_ptr2);
1659 			printf(".%.9d %s", nsec2, buf);
1660 		}
1661 		printf("\n");
1662 	}
1663 }
1664 
1665 /*
1666  * Prints n number of space characters either by using tab
1667  * or single space characters.
1668  * nc is the preceding number of characters
1669  */
1670 static void
1671 print_space(int nc, int n, int flags) {
1672 	int i, col;
1673 
1674 	col = n;
1675 	if ((flags & D_EXPANDTABS) == 0) {
1676 		/* first tabstop may be closer than tabsize */
1677 		i = tabsize - (nc % tabsize);
1678 		while (col >= tabsize) {
1679 			printf("\t");
1680 			col -= i;
1681 			i = tabsize;
1682 		}
1683 	}
1684 	printf("%*s", col, "");
1685 }
1686