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Date:: Fri Feb 8 11:18:15 2019 UTC
Message:: expand stupid argv-style parameters of merge_diff3()
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1 /*	$OpenBSD: diff3.c,v 1.41 2016/10/18 21:06:52 millert Exp $	*/
2 
3 /*
4  * Copyright (C) Caldera International Inc.  2001-2002.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code and documentation must retain the above
11  *    copyright notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed or owned by Caldera
18  *	International, Inc.
19  * 4. Neither the name of Caldera International, Inc. nor the names of other
20  *    contributors may be used to endorse or promote products derived from
21  *    this software without specific prior written permission.
22  *
23  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
24  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
28  * INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
30  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
32  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
33  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34  * POSSIBILITY OF SUCH DAMAGE.
35  */
36 /*-
37  * Copyright (c) 1991, 1993
38  *	The Regents of the University of California.  All rights reserved.
39  *
40  * Redistribution and use in source and binary forms, with or without
41  * modification, are permitted provided that the following conditions
42  * are met:
43  * 1. Redistributions of source code must retain the above copyright
44  *    notice, this list of conditions and the following disclaimer.
45  * 2. Redistributions in binary form must reproduce the above copyright
46  *    notice, this list of conditions and the following disclaimer in the
47  *    documentation and/or other materials provided with the distribution.
48  * 3. Neither the name of the University nor the names of its contributors
49  *    may be used to endorse or promote products derived from this software
50  *    without specific prior written permission.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62  * SUCH DAMAGE.
63  *
64  *	@(#)diff3.c	8.1 (Berkeley) 6/6/93
65  */
66 
67 #include <sys/stat.h>
68 #include <sys/queue.h>
69 
70 #include <ctype.h>
71 #include <limits.h>
72 #include <stdio.h>
73 #include <stdarg.h>
74 #include <stdlib.h>
75 #include <string.h>
76 #include <time.h>
77 #include <unistd.h>
78 
79 #include "got_error.h"
80 #include "got_opentemp.h"
81 #include "got_object.h"
82 
83 #include "buf.h"
84 #include "rcsutil.h"
85 #include "got_lib_diff.h"
86 #include "worklist.h"
87 
88 #ifndef nitems
89 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
90 #endif
91 
92 /* flags shared between merge(1) and rcsmerge(1) */
93 #define MERGE_EFLAG     (1<<16)
94 #define MERGE_OFLAG     (1<<17)
95 
96 /* diff3 - 3-way differential file comparison */
97 
98 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
99  *
100  * d13 = diff report on f1 vs f3
101  * d23 = diff report on f2 vs f3
102  * f1, f2, f3 the 3 files
103  * if changes in f1 overlap with changes in f3, m1 and m3 are used
104  * to mark the overlaps; otherwise, the file names f1 and f3 are used
105  * (only for options E and X).
106  */
107 
108 /*
109  * "from" is first in range of changed lines; "to" is last+1
110  * from=to=line after point of insertion for added lines.
111  */
112 struct range {
113 	int from;
114 	int to;
115 };
116 
117 struct diff {
118 	struct range old;
119 	struct range new;
120 };
121 
122 struct diff3_state {
123 	size_t szchanges;
124 
125 	struct diff *d13;
126 	struct diff *d23;
127 
128 	/*
129 	 * "de" is used to gather editing scripts.  These are later spewed out
130 	 * in reverse order.  Its first element must be all zero, the "new"
131 	 * component of "de" contains line positions or byte positions
132 	 * depending on when you look (!?).  Array overlap indicates which
133 	 * sections in "de" correspond to lines that are different in all
134 	 * three files.
135 	 */
136 	struct diff *de;
137 	char *overlap;
138 	int overlapcnt;
139 	FILE *fp[3];
140 	int cline[3];		/* # of the last-read line in each file (0-2) */
141 
142 	/*
143 	 * the latest known correspondence between line numbers of the 3 files
144 	 * is stored in last[1-3];
145 	 */
146 	int last[4];
147 	int eflag;
148 	int oflag;
149 	int debug;
150 	char f1mark[PATH_MAX], f3mark[PATH_MAX]; /* markers for -E and -X */
151 
152 	char *buf;
153 	size_t bufsize;
154 };
155 
156 static BUF *diffbuf;
157 
158 static int duplicate(struct range *, struct range *, struct diff3_state *);
159 static int edit(struct diff *, int, int, struct diff3_state *);
160 static char *getchange(FILE *, struct diff3_state *);
161 static char *get_line(FILE *, size_t *, struct diff3_state *);
162 static int number(char **);
163 static const struct got_error *readin(size_t *, char *, struct diff **,
164     struct diff3_state *);
165 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
166 static int skip(int, int, char *, struct diff3_state *);
167 static int edscript(int, struct diff3_state *);
168 static int merge(size_t, size_t, struct diff3_state *);
169 static void change(int, struct range *, int, struct diff3_state *);
170 static void keep(int, struct range *, struct diff3_state *);
171 static void prange(struct range *);
172 static void repos(int, struct diff3_state *);
173 static void separate(const char *);
174 static const struct got_error *increase(struct diff3_state *);
175 static const struct got_error *diff3_internal(char *, char *, char *,
176     char *, char *, const char *, const char *, struct diff3_state *);
177 
178 int diff3_conflicts = 0;
179 
180 static const struct got_error *
181 diff_output(const char *fmt, ...)
182 {
183 	va_list vap;
184 	int i;
185 	char *str;
186 	size_t newsize;
187 
188 	va_start(vap, fmt);
189 	i = vasprintf(&str, fmt, vap);
190 	va_end(vap);
191 	if (i == -1)
192 		return got_error_from_errno();
193 	if (diffbuf != NULL)
194 		buf_append(&newsize, diffbuf, str, strlen(str));
195 	else
196 		printf("%s", str);
197 	free(str);
198 	return NULL;
199 }
200 
201 static const struct got_error*
202 diffreg(BUF **d, const char *path1, const char *path2)
203 {
204 	const struct got_error *err = NULL;
205 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
206 	char *outpath = NULL;
207 	struct got_diff_state ds;
208 	struct got_diff_args args;
209 	int res;
210 
211 	*d = NULL;
212 
213 	f1 = fopen(path1, "r");
214 	if (f1 == NULL) {
215 		err = got_error_from_errno();
216 		goto done;
217 	}
218 	f2 = fopen(path2, "r");
219 	if (f1 == NULL) {
220 		err = got_error_from_errno();
221 		goto done;
222 	}
223 
224 	err = got_opentemp_named(&outpath, &outfile, "/tmp/got-diff");
225 	if (err)
226 		goto done;
227 
228 	memset(&ds, 0, sizeof(ds));
229 	/* XXX should stat buffers be passed in args instead of ds? */
230 	if (stat(path1, &ds.stb1) == -1) {
231 		err = got_error_from_errno();
232 		goto done;
233 	}
234 	if (stat(path2, &ds.stb2) == -1) {
235 		err = got_error_from_errno();
236 		goto done;
237 	}
238 
239 	memset(&args, 0, sizeof(args));
240 	args.diff_format = D_NORMAL;
241 	args.label[0] = "";
242 	args.label[1] = "";
243 	args.diff_context = 0;
244 
245 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
246 	    outfile, NULL);
247 	if (err)
248 		goto done;
249 
250 	*d = buf_load(outpath);
251 	if (*d == NULL)
252 		err = got_error_from_errno();
253 done:
254 	free(outpath);
255 	if (outfile)
256 		fclose(outfile);
257 	if (f1)
258 		fclose(f1);
259 	if (f2)
260 		fclose(f2);
261 	return err;
262 }
263 
264 /*
265  * For merge(1).
266  */
267 const struct got_error *
268 merge_diff3(BUF **buf, char *p1, char *p2, char *p3, int flags)
269 {
270 	const struct got_error *err = NULL;
271 	char *dp13, *dp23, *path1, *path2, *path3;
272 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
273 	u_char *data, *patch;
274 	size_t dlen, plen;
275 	struct wklhead temp_files;
276 	struct diff3_state *d3s;
277 	int i;
278 
279 	*buf = NULL;
280 
281 	d3s = calloc(1, sizeof(*d3s));
282 	if (d3s == NULL)
283 		return got_error_from_errno();
284 	d3s->eflag = 3; /* default -E for compatibility with former RCS */
285 	d3s->oflag = 1; /* default -E for compatibility with former RCS */
286 
287 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
288 	dp13 = dp23 = path1 = path2 = path3 = NULL;
289 	data = patch = NULL;
290 
291 	if ((flags & MERGE_EFLAG) && !(flags & MERGE_OFLAG))
292 		d3s->oflag = 0;
293 
294 	if ((b1 = buf_load(p1)) == NULL)
295 		goto out;
296 	if ((b2 = buf_load(p2)) == NULL)
297 		goto out;
298 	if ((b3 = buf_load(p3)) == NULL)
299 		goto out;
300 
301 	diffb = buf_alloc(128);
302 
303 	if (asprintf(&path1, "/tmp/got-diff1.XXXXXXXX") == -1) {
304 		err = got_error_from_errno();
305 		goto out;
306 	}
307 	if (asprintf(&path2, "/tmp/got-diff2.XXXXXXXX") == -1) {
308 		err = got_error_from_errno();
309 		goto out;
310 	}
311 	if (asprintf(&path3, "/tmp/got-diff3.XXXXXXXX") == -1) {
312 		err = got_error_from_errno();
313 		goto out;
314 	}
315 
316 	err = buf_write_stmp(b1, path1, &temp_files);
317 	if (err)
318 		goto out;
319 	err = buf_write_stmp(b2, path2, &temp_files);
320 	if (err)
321 		goto out;
322 	err = buf_write_stmp(b3, path3, &temp_files);
323 	if (err)
324 		goto out;
325 
326 	buf_free(b2);
327 	b2 = NULL;
328 
329 	err = diffreg(&d1, path1, path3);
330 	if (err) {
331 		buf_free(diffb);
332 		diffb = NULL;
333 		goto out;
334 
335 	}
336 	err = diffreg(&d2, path2, path3);
337 	if (err) {
338 		buf_free(diffb);
339 		diffb = NULL;
340 		goto out;
341 	}
342 
343 	if (asprintf(&dp13, "/tmp/got-d13.XXXXXXXXXX") == -1) {
344 		err = got_error_from_errno();
345 		goto out;
346 	}
347 	err = buf_write_stmp(d1, dp13, &temp_files);
348 	if (err)
349 		goto out;
350 
351 	buf_free(d1);
352 	d1 = NULL;
353 
354 	if (asprintf(&dp23, "/tmp/got-d23.XXXXXXXXXX") == -1) {
355 		err = got_error_from_errno();
356 		goto out;
357 	}
358 	err = buf_write_stmp(d2, dp23, &temp_files);
359 	if (err)
360 		goto out;
361 
362 	buf_free(d2);
363 	d2 = NULL;
364 
365 	diffbuf = diffb;
366 	err = diff3_internal(dp13, dp23, path1, path2, path3, p1, p3,
367 	    d3s);
368 	if (err) {
369 		buf_free(diffb);
370 		diffb = NULL;
371 		goto out;
372 	}
373 
374 	plen = buf_len(diffb);
375 	patch = buf_release(diffb);
376 	dlen = buf_len(b1);
377 	data = buf_release(b1);
378 
379 	if ((diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines)) == NULL)
380 		goto out;
381 out:
382 	buf_free(b2);
383 	buf_free(b3);
384 	buf_free(d1);
385 	buf_free(d2);
386 
387 	(void)unlink(path1);
388 	(void)unlink(path2);
389 	(void)unlink(path3);
390 	(void)unlink(dp13);
391 	(void)unlink(dp23);
392 
393 	free(path1);
394 	free(path2);
395 	free(path3);
396 	free(dp13);
397 	free(dp23);
398 	free(data);
399 	free(patch);
400 
401 	worklist_clean(&temp_files, worklist_unlink);
402 
403 	for (i = 0; i < nitems(d3s->fp); i++) {
404 		if (d3s->fp[i])
405 			fclose(d3s->fp[i]);
406 	}
407 	free(d3s);
408 	if (err == NULL)
409 		*buf = diffb;
410 	return err;
411 }
412 
413 static const struct got_error *
414 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
415     const char *fmark, const char *rmark, struct diff3_state *d3s)
416 {
417 	const struct got_error *err = NULL;
418 	ssize_t m, n;
419 	int i;
420 
421 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark), "<<<<<<< %s", fmark);
422 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
423 		return got_error(GOT_ERR_NO_SPACE);
424 
425 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark), ">>>>>>> %s", rmark);
426 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
427 		return got_error(GOT_ERR_NO_SPACE);
428 
429 	err = increase(d3s);
430 	if (err)
431 		return err;
432 
433 	err = readin(&m, dp13, &d3s->d13, d3s);
434 	if (err)
435 		return err;
436 	err = readin(&n, dp23, &d3s->d23, d3s);
437 	if (err)
438 		return err;
439 
440 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
441 		return got_error_from_errno();
442 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
443 		return got_error_from_errno();
444 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
445 		return got_error_from_errno();
446 
447 	if (merge(m, n, d3s) < 0)
448 		return got_error_from_errno();
449 	return NULL;
450 }
451 
452 static int
453 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
454 {
455 	char op, *ep;
456 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
457 	int start, end, i, lineno;
458 	u_char tmp;
459 
460 	dlp = TAILQ_FIRST(&(dlines->l_lines));
461 	lp = TAILQ_FIRST(&(plines->l_lines));
462 
463 	end = 0;
464 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
465 	    lp = TAILQ_NEXT(lp, l_list)) {
466 		/* Skip blank lines */
467 		if (lp->l_len < 2)
468 			continue;
469 
470 		/* NUL-terminate line buffer for strtol() safety. */
471 		tmp = lp->l_line[lp->l_len - 1];
472 		lp->l_line[lp->l_len - 1] = '\0';
473 
474 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
475 		op = lp->l_line[lp->l_len - 2];
476 		start = (int)strtol(lp->l_line, &ep, 10);
477 
478 		/* Restore the last byte of the buffer */
479 		lp->l_line[lp->l_len - 1] = tmp;
480 
481 		if (op == 'a') {
482 			if (start > dlines->l_nblines ||
483 			    start < 0 || *ep != 'a')
484 				return -1;
485 		} else if (op == 'c') {
486 			if (start > dlines->l_nblines ||
487 			    start < 0 || (*ep != ',' && *ep != 'c'))
488 				return -1;
489 
490 			if (*ep == ',') {
491 				ep++;
492 				end = (int)strtol(ep, &ep, 10);
493 				if (end < 0 || *ep != 'c')
494 					return -1;
495 			} else {
496 				end = start;
497 			}
498 		}
499 
500 
501 		for (;;) {
502 			if (dlp == NULL)
503 				break;
504 			if (dlp->l_lineno == start)
505 				break;
506 			if (dlp->l_lineno > start) {
507 				dlp = TAILQ_PREV(dlp, tqh, l_list);
508 			} else if (dlp->l_lineno < start) {
509 				ndlp = TAILQ_NEXT(dlp, l_list);
510 				if (ndlp->l_lineno > start)
511 					break;
512 				dlp = ndlp;
513 			}
514 		}
515 
516 		if (dlp == NULL)
517 			return -1;
518 
519 
520 		if (op == 'c') {
521 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
522 			for (i = 0; i <= (end - start); i++) {
523 				ndlp = TAILQ_NEXT(dlp, l_list);
524 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
525 				dlp = ndlp;
526 			}
527 			dlp = insert_after;
528 		}
529 
530 		if (op == 'a' || op == 'c') {
531 			for (;;) {
532 				ndlp = lp;
533 				lp = TAILQ_NEXT(lp, l_list);
534 				if (lp == NULL)
535 					return -1;
536 
537 				if (!memcmp(lp->l_line, ".", 1))
538 					break;
539 
540 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
541 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
542 				    lp, l_list);
543 				dlp = lp;
544 
545 				lp->l_lineno = start;
546 				lp = ndlp;
547 			}
548 		}
549 
550 		/*
551 		 * always resort lines as the markers might be put at the
552 		 * same line as we first started editing.
553 		 */
554 		lineno = 0;
555 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
556 			sort->l_lineno = lineno++;
557 		dlines->l_nblines = lineno - 1;
558 	}
559 
560 	return (0);
561 }
562 
563 /*
564  * Pick up the line numbers of all changes from one change file.
565  * (This puts the numbers in a vector, which is not strictly necessary,
566  * since the vector is processed in one sequential pass.
567  * The vector could be optimized out of existence)
568  */
569 static const struct got_error *
570 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
571 {
572 	const struct got_error *err = NULL;
573 	int a, b, c, d;
574 	char kind, *p;
575 	size_t i;
576 
577 	d3s->fp[0] = fopen(name, "r");
578 	if (d3s->fp[0] == NULL)
579 		return got_error_from_errno();
580 	for (i = 0; (p = getchange(d3s->fp[0], d3s)); i++) {
581 		if (i >= d3s->szchanges - 1) {
582 			err = increase(d3s);
583 			if (err)
584 				return err;
585 		}
586 		a = b = number(&p);
587 		if (*p == ',') {
588 			p++;
589 			b = number(&p);
590 		}
591 		kind = *p++;
592 		c = d = number(&p);
593 		if (*p==',') {
594 			p++;
595 			d = number(&p);
596 		}
597 		if (kind == 'a')
598 			a++;
599 		if (kind == 'd')
600 			c++;
601 		b++;
602 		d++;
603 		(*dd)[i].old.from = a;
604 		(*dd)[i].old.to = b;
605 		(*dd)[i].new.from = c;
606 		(*dd)[i].new.to = d;
607 	}
608 
609 	if (i) {
610 		(*dd)[i].old.from = (*dd)[i-1].old.to;
611 		(*dd)[i].new.from = (*dd)[i-1].new.to;
612 	}
613 
614 	(void)fclose(d3s->fp[0]);
615 
616 	return NULL;
617 }
618 
619 static int
620 number(char **lc)
621 {
622 	int nn;
623 
624 	nn = 0;
625 	while (isdigit((unsigned char)(**lc)))
626 		nn = nn*10 + *(*lc)++ - '0';
627 
628 	return (nn);
629 }
630 
631 static char *
632 getchange(FILE *b, struct diff3_state *d3s)
633 {
634 	char *line;
635 
636 	while ((line = get_line(b, NULL, d3s))) {
637 		if (isdigit((unsigned char)line[0]))
638 			return (line);
639 	}
640 
641 	return (NULL);
642 }
643 
644 static char *
645 get_line(FILE *b, size_t *n, struct diff3_state *d3s)
646 {
647 	char *cp;
648 	size_t len;
649 	char *new;
650 
651 	if ((cp = fgetln(b, &len)) == NULL)
652 		return (NULL);
653 
654 	if (cp[len - 1] != '\n')
655 		len++;
656 	if (len + 1 > d3s->bufsize) {
657 		do {
658 			d3s->bufsize += 1024;
659 		} while (len + 1 > d3s->bufsize);
660 		new = reallocarray(d3s->buf, 1, d3s->bufsize);
661 		if (new == NULL)
662 			return NULL;
663 		d3s->buf = new;
664 	}
665 	memcpy(d3s->buf, cp, len - 1);
666 	d3s->buf[len - 1] = '\n';
667 	d3s->buf[len] = '\0';
668 	if (n != NULL)
669 		*n = len;
670 
671 	return (d3s->buf);
672 }
673 
674 static int
675 merge(size_t m1, size_t m2, struct diff3_state *d3s)
676 {
677 	struct diff *d1, *d2, *d3;
678 	int dpl, j, t1, t2;
679 
680 	d1 = d3s->d13;
681 	d2 = d3s->d23;
682 	j = 0;
683 	for (;;) {
684 		t1 = (d1 < d3s->d13 + m1);
685 		t2 = (d2 < d3s->d23 + m2);
686 		if (!t1 && !t2)
687 			break;
688 
689 		if (d3s->debug) {
690 			printf("%d,%d=%d,%d %d,%d=%d,%d\n",
691 			d1->old.from, d1->old.to,
692 			d1->new.from, d1->new.to,
693 			d2->old.from, d2->old.to,
694 			d2->new.from, d2->new.to);
695 		}
696 
697 		/* first file is different from others */
698 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
699 			/* stuff peculiar to 1st file */
700 			if (d3s->eflag == 0) {
701 				separate("1");
702 				change(1, &d1->old, 0, d3s);
703 				keep(2, &d1->new, d3s);
704 				change(3, &d1->new, 0, d3s);
705 			}
706 			d1++;
707 			continue;
708 		}
709 
710 		/* second file is different from others */
711 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
712 			if (d3s->eflag == 0) {
713 				separate("2");
714 				keep(1, &d2->new, d3s);
715 				change(2, &d2->old, 0, d3s);
716 				change(3, &d2->new, 0, d3s);
717 			}
718 			d2++;
719 			continue;
720 		}
721 
722 		/*
723 		 * Merge overlapping changes in first file
724 		 * this happens after extension (see below).
725 		 */
726 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
727 			d1[1].old.from = d1->old.from;
728 			d1[1].new.from = d1->new.from;
729 			d1++;
730 			continue;
731 		}
732 
733 		/* merge overlapping changes in second */
734 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
735 			d2[1].old.from = d2->old.from;
736 			d2[1].new.from = d2->new.from;
737 			d2++;
738 			continue;
739 		}
740 		/* stuff peculiar to third file or different in all */
741 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
742 			dpl = duplicate(&d1->old, &d2->old, d3s);
743 			if (dpl == -1)
744 				return (-1);
745 
746 			/*
747 			 * dpl = 0 means all files differ
748 			 * dpl = 1 means files 1 and 2 identical
749 			 */
750 			if (d3s->eflag == 0) {
751 				separate(dpl ? "3" : "");
752 				change(1, &d1->old, dpl, d3s);
753 				change(2, &d2->old, 0, d3s);
754 				d3 = d1->old.to > d1->old.from ? d1 : d2;
755 				change(3, &d3->new, 0, d3s);
756 			} else
757 				j = edit(d1, dpl, j, d3s);
758 			d1++;
759 			d2++;
760 			continue;
761 		}
762 
763 		/*
764 		 * Overlapping changes from file 1 and 2; extend changes
765 		 * appropriately to make them coincide.
766 		 */
767 		if (d1->new.from < d2->new.from) {
768 			d2->old.from -= d2->new.from-d1->new.from;
769 			d2->new.from = d1->new.from;
770 		} else if (d2->new.from < d1->new.from) {
771 			d1->old.from -= d1->new.from-d2->new.from;
772 			d1->new.from = d2->new.from;
773 		}
774 		if (d1->new.to > d2->new.to) {
775 			d2->old.to += d1->new.to - d2->new.to;
776 			d2->new.to = d1->new.to;
777 		} else if (d2->new.to > d1->new.to) {
778 			d1->old.to += d2->new.to - d1->new.to;
779 			d1->new.to = d2->new.to;
780 		}
781 	}
782 
783 	return (edscript(j, d3s));
784 }
785 
786 static void
787 separate(const char *s)
788 {
789 	diff_output("====%s\n", s);
790 }
791 
792 /*
793  * The range of lines rold.from thru rold.to in file i is to be changed.
794  * It is to be printed only if it does not duplicate something to be
795  * printed later.
796  */
797 static void
798 change(int i, struct range *rold, int fdup, struct diff3_state *d3s)
799 {
800 	diff_output("%d:", i);
801 	d3s->last[i] = rold->to;
802 	prange(rold);
803 	if (fdup || d3s->debug)
804 		return;
805 	i--;
806 	(void)skip(i, rold->from, NULL, d3s);
807 	(void)skip(i, rold->to, "  ", d3s);
808 }
809 
810 /*
811  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
812  */
813 static void
814 prange(struct range *rold)
815 {
816 	if (rold->to <= rold->from)
817 		diff_output("%da\n", rold->from - 1);
818 	else {
819 		diff_output("%d", rold->from);
820 		if (rold->to > rold->from+1)
821 			diff_output(",%d", rold->to - 1);
822 		diff_output("c\n");
823 	}
824 }
825 
826 /*
827  * No difference was reported by diff between file 1 (or 2) and file 3,
828  * and an artificial dummy difference (trange) must be ginned up to
829  * correspond to the change reported in the other file.
830  */
831 static void
832 keep(int i, struct range *rnew, struct diff3_state *d3s)
833 {
834 	int delta;
835 	struct range trange;
836 
837 	delta = d3s->last[3] - d3s->last[i];
838 	trange.from = rnew->from - delta;
839 	trange.to = rnew->to - delta;
840 	change(i, &trange, 1, d3s);
841 }
842 
843 /*
844  * skip to just before line number from in file "i".  If "pr" is non-NULL,
845  * print all skipped stuff with string pr as a prefix.
846  */
847 static int
848 skip(int i, int from, char *pr, struct diff3_state *d3s)
849 {
850 	size_t j, n;
851 	char *line;
852 
853 	for (n = 0; d3s->cline[i] < from - 1; n += j) {
854 		if ((line = get_line(d3s->fp[i], &j, d3s)) == NULL)
855 			return (-1);
856 		if (pr != NULL)
857 			diff_output("%s%s", pr, line);
858 		d3s->cline[i]++;
859 	}
860 	return ((int) n);
861 }
862 
863 /*
864  * Return 1 or 0 according as the old range (in file 1) contains exactly
865  * the same data as the new range (in file 2).
866  */
867 static int
868 duplicate(struct range *r1, struct range *r2, struct diff3_state *d3s)
869 {
870 	int c,d;
871 	int nchar;
872 	int nline;
873 
874 	if (r1->to-r1->from != r2->to-r2->from)
875 		return (0);
876 	(void)skip(0, r1->from, NULL, d3s);
877 	(void)skip(1, r2->from, NULL, d3s);
878 	nchar = 0;
879 	for (nline=0; nline < r1->to - r1->from; nline++) {
880 		do {
881 			c = getc(d3s->fp[0]);
882 			d = getc(d3s->fp[1]);
883 			if (c == -1 || d== -1)
884 				return (-1);
885 			nchar++;
886 			if (c != d) {
887 				repos(nchar, d3s);
888 				return (0);
889 			}
890 		} while (c != '\n');
891 	}
892 	repos(nchar, d3s);
893 	return (1);
894 }
895 
896 static void
897 repos(int nchar, struct diff3_state *d3s)
898 {
899 	int i;
900 
901 	for (i = 0; i < 2; i++)
902 		(void)fseek(d3s->fp[i], (long)-nchar, SEEK_CUR);
903 }
904 
905 /*
906  * collect an editing script for later regurgitation
907  */
908 static int
909 edit(struct diff *diff, int fdup, int j, struct diff3_state *d3s)
910 {
911 	if (((fdup + 1) & d3s->eflag) == 0)
912 		return (j);
913 	j++;
914 	d3s->overlap[j] = !fdup;
915 	if (!fdup)
916 		d3s->overlapcnt++;
917 	d3s->de[j].old.from = diff->old.from;
918 	d3s->de[j].old.to = diff->old.to;
919 	d3s->de[j].new.from =
920 	    d3s->de[j-1].new.to + skip(2, diff->new.from, NULL, d3s);
921 	d3s->de[j].new.to =
922 	    d3s->de[j].new.from + skip(2, diff->new.to, NULL, d3s);
923 	return (j);
924 }
925 
926 /* regurgitate */
927 static int
928 edscript(int n, struct diff3_state *d3s)
929 {
930 	int j, k;
931 	char block[BUFSIZ+1];
932 
933 	for (; n > 0; n--) {
934 		if (!d3s->oflag || !d3s->overlap[n])
935 			prange(&d3s->de[n].old);
936 		else
937 			diff_output("%da\n=======\n", d3s->de[n].old.to -1);
938 		(void)fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET);
939 		k = d3s->de[n].new.to - d3s->de[n].new.from;
940 		for (; k > 0; k-= j) {
941 			j = k > BUFSIZ ? BUFSIZ : k;
942 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
943 				return (-1);
944 			block[j] = '\0';
945 			diff_output("%s", block);
946 		}
947 
948 		if (!d3s->oflag || !d3s->overlap[n])
949 			diff_output(".\n");
950 		else {
951 			diff_output("%s\n.\n", d3s->f3mark);
952 			diff_output("%da\n%s\n.\n", d3s->de[n].old.from - 1,
953 			    d3s->f1mark);
954 		}
955 	}
956 
957 	return (d3s->overlapcnt);
958 }
959 
960 static const struct got_error *
961 increase(struct diff3_state *d3s)
962 {
963 	size_t newsz, incr;
964 	struct diff *d;
965 	char *s;
966 
967 	/* are the memset(3) calls needed? */
968 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
969 	incr = newsz - d3s->szchanges;
970 
971 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
972 	if (d == NULL)
973 		return got_error_from_errno();
974 	d3s->d13 = d;
975 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
976 
977 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
978 	if (d == NULL)
979 		return got_error_from_errno();
980 	d3s->d23 = d;
981 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
982 
983 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
984 	if (d == NULL)
985 		return got_error_from_errno();
986 	d3s->de = d;
987 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
988 
989 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
990 	if (s == NULL)
991 		return got_error_from_errno();
992 	d3s->overlap = s;
993 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
994 	d3s->szchanges = newsz;
995 
996 	return NULL;
997 }