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Date:: Mon May 13 16:40:57 2019 UTC
Message:: rename got_error_prefix_errno() to got_error_from_errno()
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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 /* diff3 - 3-way differential file comparison */
93 
94 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
95  *
96  * d13 = diff report on f1 vs f3
97  * d23 = diff report on f2 vs f3
98  * f1, f2, f3 the 3 files
99  * if changes in f1 overlap with changes in f3, m1 and m3 are used
100  * to mark the overlaps; otherwise, the file names f1 and f3 are used
101  * (only for options E and X).
102  */
103 
104 /*
105  * "from" is first in range of changed lines; "to" is last+1
106  * from=to=line after point of insertion for added lines.
107  */
108 struct range {
109 	int from;
110 	int to;
111 };
112 
113 struct diff {
114 	struct range old;
115 	struct range new;
116 };
117 
118 struct diff3_state {
119 	size_t szchanges;
120 
121 	struct diff *d13;
122 	struct diff *d23;
123 
124 	/*
125 	 * "de" is used to gather editing scripts.  These are later spewed out
126 	 * in reverse order.  Its first element must be all zero, the "new"
127 	 * component of "de" contains line positions or byte positions
128 	 * depending on when you look (!?).  Array overlap indicates which
129 	 * sections in "de" correspond to lines that are different in all
130 	 * three files.
131 	 */
132 	struct diff *de;
133 	char *overlap;
134 	int overlapcnt;
135 	FILE *fp[3];
136 	int cline[3];		/* # of the last-read line in each file (0-2) */
137 
138 	/*
139 	 * the latest known correspondence between line numbers of the 3 files
140 	 * is stored in last[1-3];
141 	 */
142 	int last[4];
143 	int eflag;
144 	int oflag;
145 	int debug;
146 	char f1mark[PATH_MAX], f3mark[PATH_MAX]; /* markers for -E and -X */
147 
148 	char *buf;
149 	size_t bufsize;
150 
151 	BUF *diffbuf;
152 };
153 
154 
155 static int duplicate(struct range *, struct range *, struct diff3_state *);
156 static int edit(struct diff *, int, int, struct diff3_state *);
157 static char *getchange(FILE *, struct diff3_state *);
158 static char *get_line(FILE *, size_t *, struct diff3_state *);
159 static int number(char **);
160 static const struct got_error *readin(size_t *, char *, struct diff **,
161     struct diff3_state *);
162 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
163 static int skip(int, int, char *, struct diff3_state *);
164 static int edscript(int, struct diff3_state *);
165 static int merge(size_t, size_t, struct diff3_state *);
166 static void change(int, struct range *, int, struct diff3_state *);
167 static void keep(int, struct range *, struct diff3_state *);
168 static void prange(struct range *, struct diff3_state *);
169 static void repos(int, struct diff3_state *);
170 static void separate(const char *, struct diff3_state *);
171 static const struct got_error *increase(struct diff3_state *);
172 static const struct got_error *diff3_internal(char *, char *, char *,
173     char *, char *, const char *, const char *, struct diff3_state *,
174     const char *, const char *);
175 
176 static const struct got_error *
177 diff_output(BUF *diffbuf, const char *fmt, ...)
178 {
179 	va_list vap;
180 	int i;
181 	char *str;
182 	size_t newsize;
183 
184 	va_start(vap, fmt);
185 	i = vasprintf(&str, fmt, vap);
186 	va_end(vap);
187 	if (i == -1)
188 		return got_error_from_errno("vasprintf");
189 	buf_append(&newsize, diffbuf, str, strlen(str));
190 	free(str);
191 	return NULL;
192 }
193 
194 static const struct got_error*
195 diffreg(BUF **d, const char *path1, const char *path2)
196 {
197 	const struct got_error *err = NULL;
198 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
199 	char *outpath = NULL;
200 	struct got_diff_state ds;
201 	struct got_diff_args args;
202 	int res;
203 
204 	*d = NULL;
205 
206 	f1 = fopen(path1, "r");
207 	if (f1 == NULL) {
208 		err = got_error_from_errno2("fopen", path1);
209 		goto done;
210 	}
211 	f2 = fopen(path2, "r");
212 	if (f1 == NULL) {
213 		err = got_error_from_errno2("fopen", path2);
214 		goto done;
215 	}
216 
217 	err = got_opentemp_named(&outpath, &outfile, "/tmp/got-diffreg");
218 	if (err)
219 		goto done;
220 
221 	memset(&ds, 0, sizeof(ds));
222 	/* XXX should stat buffers be passed in args instead of ds? */
223 	if (stat(path1, &ds.stb1) == -1) {
224 		err = got_error_from_errno2("stat", path1);
225 		goto done;
226 	}
227 	if (stat(path2, &ds.stb2) == -1) {
228 		err = got_error_from_errno2("stat", path2);
229 		goto done;
230 	}
231 
232 	memset(&args, 0, sizeof(args));
233 	args.diff_format = D_NORMAL;
234 	args.label[0] = "";
235 	args.label[1] = "";
236 	args.diff_context = 0;
237 
238 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
239 	    outfile, NULL);
240 	if (err)
241 		goto done;
242 
243 	if (fflush(outfile) != 0) {
244 		err = got_error_from_errno2("fflush", outpath);
245 		goto done;
246 	}
247 
248 	*d = buf_load(outpath);
249 	if (*d == NULL)
250 		err = got_error_from_errno("buf_load");
251 done:
252 	if (outpath) {
253 		unlink(outpath);
254 		free(outpath);
255 	}
256 	if (outfile && fclose(outfile) != 0 && err == NULL)
257 		err = got_error_from_errno("fclose");
258 	if (f1 && fclose(f1) != 0 && err == NULL)
259 		err = got_error_from_errno("fclose");
260 	if (f2 && fclose(f2) != 0 && err == NULL)
261 		err = got_error_from_errno("fclose");
262 	return err;
263 }
264 
265 /*
266  * For merge(1).
267  */
268 const struct got_error *
269 got_merge_diff3(int *overlapcnt, int outfd, const char *p1, const char *p2,
270     const char *p3, const char *label1, const char *label3)
271 {
272 	const struct got_error *err = NULL;
273 	char *dp13, *dp23, *path1, *path2, *path3;
274 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
275 	u_char *data, *patch;
276 	size_t dlen, plen;
277 	struct wklhead temp_files;
278 	struct diff3_state *d3s;
279 	int i;
280 
281 	*overlapcnt = 0;
282 
283 	SLIST_INIT(&temp_files);
284 
285 	d3s = calloc(1, sizeof(*d3s));
286 	if (d3s == NULL)
287 		return got_error_from_errno("calloc");
288 	d3s->eflag = 3; /* default -E for compatibility with former RCS */
289 	d3s->oflag = 1; /* default -E for compatibility with former RCS */
290 
291 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
292 	dp13 = dp23 = path1 = path2 = path3 = NULL;
293 	data = patch = NULL;
294 
295 	if ((b1 = buf_load(p1)) == NULL)
296 		goto out;
297 	if ((b2 = buf_load(p2)) == NULL)
298 		goto out;
299 	if ((b3 = buf_load(p3)) == NULL)
300 		goto out;
301 
302 	diffb = buf_alloc(128);
303 
304 	if (asprintf(&path1, "/tmp/got-diff1.XXXXXXXX") == -1) {
305 		err = got_error_from_errno("asprintf");
306 		goto out;
307 	}
308 	if (asprintf(&path2, "/tmp/got-diff2.XXXXXXXX") == -1) {
309 		err = got_error_from_errno("asprintf");
310 		goto out;
311 	}
312 	if (asprintf(&path3, "/tmp/got-diff3.XXXXXXXX") == -1) {
313 		err = got_error_from_errno("asprintf");
314 		goto out;
315 	}
316 
317 	err = buf_write_stmp(b1, path1, &temp_files);
318 	if (err)
319 		goto out;
320 	err = buf_write_stmp(b2, path2, &temp_files);
321 	if (err)
322 		goto out;
323 	err = buf_write_stmp(b3, path3, &temp_files);
324 	if (err)
325 		goto out;
326 
327 	buf_free(b2);
328 	b2 = NULL;
329 
330 	err = diffreg(&d1, path1, path3);
331 	if (err) {
332 		buf_free(diffb);
333 		diffb = NULL;
334 		goto out;
335 
336 	}
337 	err = diffreg(&d2, path2, path3);
338 	if (err) {
339 		buf_free(diffb);
340 		diffb = NULL;
341 		goto out;
342 	}
343 
344 	if (asprintf(&dp13, "/tmp/got-d13.XXXXXXXXXX") == -1) {
345 		err = got_error_from_errno("asprintf");
346 		goto out;
347 	}
348 	err = buf_write_stmp(d1, dp13, &temp_files);
349 	if (err)
350 		goto out;
351 
352 	buf_free(d1);
353 	d1 = NULL;
354 
355 	if (asprintf(&dp23, "/tmp/got-d23.XXXXXXXXXX") == -1) {
356 		err = got_error_from_errno("asprintf");
357 		goto out;
358 	}
359 	err = buf_write_stmp(d2, dp23, &temp_files);
360 	if (err)
361 		goto out;
362 
363 	buf_free(d2);
364 	d2 = NULL;
365 
366 	d3s->diffbuf = diffb;
367 	err = diff3_internal(dp13, dp23, path1, path2, path3,
368 	    label1, label3, d3s, label1, label3);
369 	if (err) {
370 		buf_free(diffb);
371 		diffb = NULL;
372 		goto out;
373 	}
374 
375 	plen = buf_len(diffb);
376 	patch = buf_release(diffb);
377 	dlen = buf_len(b1);
378 	data = buf_release(b1);
379 
380 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
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] && fclose(d3s->fp[i]) != 0 && err == NULL)
405 			err = got_error_from_errno("fclose");
406 	}
407 	if (err == NULL && diffb) {
408 		if (buf_write_fd(diffb, outfd) < 0)
409 			err = got_error_from_errno("buf_write_fd");
410 		*overlapcnt = d3s->overlapcnt;
411 	}
412 	free(d3s);
413 	buf_free(diffb);
414 	return err;
415 }
416 
417 static const struct got_error *
418 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
419     const char *fmark, const char *rmark, struct diff3_state *d3s,
420     const char *label1, const char *label3)
421 {
422 	const struct got_error *err = NULL;
423 	ssize_t m, n;
424 	int i;
425 
426 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
427 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_BEGIN, label1);
428 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
429 		return got_error(GOT_ERR_NO_SPACE);
430 
431 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
432 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_END, label3);
433 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
434 		return got_error(GOT_ERR_NO_SPACE);
435 
436 	err = increase(d3s);
437 	if (err)
438 		return err;
439 
440 	err = readin(&m, dp13, &d3s->d13, d3s);
441 	if (err)
442 		return err;
443 	err = readin(&n, dp23, &d3s->d23, d3s);
444 	if (err)
445 		return err;
446 
447 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
448 		return got_error_from_errno2("fopen", path1);
449 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
450 		return got_error_from_errno2("fopen", path2);
451 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
452 		return got_error_from_errno2("fopen", path3);
453 
454 	if (merge(m, n, d3s) < 0)
455 		return got_error_from_errno("merge");
456 	return NULL;
457 }
458 
459 static int
460 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
461 {
462 	char op, *ep;
463 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
464 	int start, end, i, lineno;
465 	u_char tmp;
466 
467 	dlp = TAILQ_FIRST(&(dlines->l_lines));
468 	lp = TAILQ_FIRST(&(plines->l_lines));
469 
470 	end = 0;
471 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
472 	    lp = TAILQ_NEXT(lp, l_list)) {
473 		/* Skip blank lines */
474 		if (lp->l_len < 2)
475 			continue;
476 
477 		/* NUL-terminate line buffer for strtol() safety. */
478 		tmp = lp->l_line[lp->l_len - 1];
479 		lp->l_line[lp->l_len - 1] = '\0';
480 
481 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
482 		op = lp->l_line[lp->l_len - 2];
483 		start = (int)strtol(lp->l_line, &ep, 10);
484 
485 		/* Restore the last byte of the buffer */
486 		lp->l_line[lp->l_len - 1] = tmp;
487 
488 		if (op == 'a') {
489 			if (start > dlines->l_nblines ||
490 			    start < 0 || *ep != 'a')
491 				return -1;
492 		} else if (op == 'c') {
493 			if (start > dlines->l_nblines ||
494 			    start < 0 || (*ep != ',' && *ep != 'c'))
495 				return -1;
496 
497 			if (*ep == ',') {
498 				ep++;
499 				end = (int)strtol(ep, &ep, 10);
500 				if (end < 0 || *ep != 'c')
501 					return -1;
502 			} else {
503 				end = start;
504 			}
505 		}
506 
507 
508 		for (;;) {
509 			if (dlp == NULL)
510 				break;
511 			if (dlp->l_lineno == start)
512 				break;
513 			if (dlp->l_lineno > start) {
514 				dlp = TAILQ_PREV(dlp, tqh, l_list);
515 			} else if (dlp->l_lineno < start) {
516 				ndlp = TAILQ_NEXT(dlp, l_list);
517 				if (ndlp->l_lineno > start)
518 					break;
519 				dlp = ndlp;
520 			}
521 		}
522 
523 		if (dlp == NULL)
524 			return -1;
525 
526 
527 		if (op == 'c') {
528 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
529 			for (i = 0; i <= (end - start); i++) {
530 				ndlp = TAILQ_NEXT(dlp, l_list);
531 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
532 				dlp = ndlp;
533 			}
534 			dlp = insert_after;
535 		}
536 
537 		if (op == 'a' || op == 'c') {
538 			for (;;) {
539 				ndlp = lp;
540 				lp = TAILQ_NEXT(lp, l_list);
541 				if (lp == NULL)
542 					return -1;
543 
544 				if (!memcmp(lp->l_line, ".", 1))
545 					break;
546 
547 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
548 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
549 				    lp, l_list);
550 				dlp = lp;
551 
552 				lp->l_lineno = start;
553 				lp = ndlp;
554 			}
555 		}
556 
557 		/*
558 		 * always resort lines as the markers might be put at the
559 		 * same line as we first started editing.
560 		 */
561 		lineno = 0;
562 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
563 			sort->l_lineno = lineno++;
564 		dlines->l_nblines = lineno - 1;
565 	}
566 
567 	return (0);
568 }
569 
570 /*
571  * Pick up the line numbers of all changes from one change file.
572  * (This puts the numbers in a vector, which is not strictly necessary,
573  * since the vector is processed in one sequential pass.
574  * The vector could be optimized out of existence)
575  */
576 static const struct got_error *
577 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
578 {
579 	const struct got_error *err = NULL;
580 	int a, b, c, d;
581 	char kind, *p;
582 	size_t i;
583 
584 	*n = 0;
585 
586 	d3s->fp[0] = fopen(name, "r");
587 	if (d3s->fp[0] == NULL)
588 		return got_error_from_errno2("fopen", name);
589 	for (i = 0; (p = getchange(d3s->fp[0], d3s)); i++) {
590 		if (i >= d3s->szchanges - 1) {
591 			err = increase(d3s);
592 			if (err)
593 				return err;
594 		}
595 		a = b = number(&p);
596 		if (*p == ',') {
597 			p++;
598 			b = number(&p);
599 		}
600 		kind = *p++;
601 		c = d = number(&p);
602 		if (*p==',') {
603 			p++;
604 			d = number(&p);
605 		}
606 		if (kind == 'a')
607 			a++;
608 		if (kind == 'd')
609 			c++;
610 		b++;
611 		d++;
612 		(*dd)[i].old.from = a;
613 		(*dd)[i].old.to = b;
614 		(*dd)[i].new.from = c;
615 		(*dd)[i].new.to = d;
616 	}
617 
618 	if (i) {
619 		(*dd)[i].old.from = (*dd)[i-1].old.to;
620 		(*dd)[i].new.from = (*dd)[i-1].new.to;
621 	}
622 
623 	if (fclose(d3s->fp[0]) != 0)
624 		err = got_error_from_errno("fclose");
625 
626 	*n = i;
627 	return err;
628 }
629 
630 static int
631 number(char **lc)
632 {
633 	int nn;
634 
635 	nn = 0;
636 	while (isdigit((unsigned char)(**lc)))
637 		nn = nn*10 + *(*lc)++ - '0';
638 
639 	return (nn);
640 }
641 
642 static char *
643 getchange(FILE *b, struct diff3_state *d3s)
644 {
645 	char *line;
646 
647 	while ((line = get_line(b, NULL, d3s))) {
648 		if (isdigit((unsigned char)line[0]))
649 			return (line);
650 	}
651 
652 	return (NULL);
653 }
654 
655 static char *
656 get_line(FILE *b, size_t *n, struct diff3_state *d3s)
657 {
658 	char *cp;
659 	size_t len;
660 	char *new;
661 
662 	if ((cp = fgetln(b, &len)) == NULL)
663 		return (NULL);
664 
665 	if (cp[len - 1] != '\n')
666 		len++;
667 	if (len + 1 > d3s->bufsize) {
668 		do {
669 			d3s->bufsize += 1024;
670 		} while (len + 1 > d3s->bufsize);
671 		new = reallocarray(d3s->buf, 1, d3s->bufsize);
672 		if (new == NULL)
673 			return NULL;
674 		d3s->buf = new;
675 	}
676 	memcpy(d3s->buf, cp, len - 1);
677 	d3s->buf[len - 1] = '\n';
678 	d3s->buf[len] = '\0';
679 	if (n != NULL)
680 		*n = len;
681 
682 	return (d3s->buf);
683 }
684 
685 static int
686 merge(size_t m1, size_t m2, struct diff3_state *d3s)
687 {
688 	struct diff *d1, *d2, *d3;
689 	int dpl, j, t1, t2;
690 
691 	d1 = d3s->d13;
692 	d2 = d3s->d23;
693 	j = 0;
694 	for (;;) {
695 		t1 = (d1 < d3s->d13 + m1);
696 		t2 = (d2 < d3s->d23 + m2);
697 		if (!t1 && !t2)
698 			break;
699 
700 		if (d3s->debug) {
701 			printf("%d,%d=%d,%d %d,%d=%d,%d\n",
702 			d1->old.from, d1->old.to,
703 			d1->new.from, d1->new.to,
704 			d2->old.from, d2->old.to,
705 			d2->new.from, d2->new.to);
706 		}
707 
708 		/* first file is different from others */
709 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
710 			/* stuff peculiar to 1st file */
711 			if (d3s->eflag == 0) {
712 				separate("1", d3s);
713 				change(1, &d1->old, 0, d3s);
714 				keep(2, &d1->new, d3s);
715 				change(3, &d1->new, 0, d3s);
716 			}
717 			d1++;
718 			continue;
719 		}
720 
721 		/* second file is different from others */
722 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
723 			if (d3s->eflag == 0) {
724 				separate("2", d3s);
725 				keep(1, &d2->new, d3s);
726 				change(2, &d2->old, 0, d3s);
727 				change(3, &d2->new, 0, d3s);
728 			}
729 			d2++;
730 			continue;
731 		}
732 
733 		/*
734 		 * Merge overlapping changes in first file
735 		 * this happens after extension (see below).
736 		 */
737 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
738 			d1[1].old.from = d1->old.from;
739 			d1[1].new.from = d1->new.from;
740 			d1++;
741 			continue;
742 		}
743 
744 		/* merge overlapping changes in second */
745 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
746 			d2[1].old.from = d2->old.from;
747 			d2[1].new.from = d2->new.from;
748 			d2++;
749 			continue;
750 		}
751 		/* stuff peculiar to third file or different in all */
752 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
753 			dpl = duplicate(&d1->old, &d2->old, d3s);
754 			if (dpl == -1)
755 				return (-1);
756 
757 			/*
758 			 * dpl = 0 means all files differ
759 			 * dpl = 1 means files 1 and 2 identical
760 			 */
761 			if (d3s->eflag == 0) {
762 				separate(dpl ? "3" : "", d3s);
763 				change(1, &d1->old, dpl, d3s);
764 				change(2, &d2->old, 0, d3s);
765 				d3 = d1->old.to > d1->old.from ? d1 : d2;
766 				change(3, &d3->new, 0, d3s);
767 			} else
768 				j = edit(d1, dpl, j, d3s);
769 			d1++;
770 			d2++;
771 			continue;
772 		}
773 
774 		/*
775 		 * Overlapping changes from file 1 and 2; extend changes
776 		 * appropriately to make them coincide.
777 		 */
778 		if (d1->new.from < d2->new.from) {
779 			d2->old.from -= d2->new.from-d1->new.from;
780 			d2->new.from = d1->new.from;
781 		} else if (d2->new.from < d1->new.from) {
782 			d1->old.from -= d1->new.from-d2->new.from;
783 			d1->new.from = d2->new.from;
784 		}
785 		if (d1->new.to > d2->new.to) {
786 			d2->old.to += d1->new.to - d2->new.to;
787 			d2->new.to = d1->new.to;
788 		} else if (d2->new.to > d1->new.to) {
789 			d1->old.to += d2->new.to - d1->new.to;
790 			d1->new.to = d2->new.to;
791 		}
792 	}
793 
794 	return (edscript(j, d3s));
795 }
796 
797 static void
798 separate(const char *s, struct diff3_state *d3s)
799 {
800 	diff_output(d3s->diffbuf, "====%s\n", s);
801 }
802 
803 /*
804  * The range of lines rold.from thru rold.to in file i is to be changed.
805  * It is to be printed only if it does not duplicate something to be
806  * printed later.
807  */
808 static void
809 change(int i, struct range *rold, int fdup, struct diff3_state *d3s)
810 {
811 	diff_output(d3s->diffbuf, "%d:", i);
812 	d3s->last[i] = rold->to;
813 	prange(rold, d3s);
814 	if (fdup || d3s->debug)
815 		return;
816 	i--;
817 	(void)skip(i, rold->from, NULL, d3s);
818 	(void)skip(i, rold->to, "  ", d3s);
819 }
820 
821 /*
822  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
823  */
824 static void
825 prange(struct range *rold, struct diff3_state *d3s)
826 {
827 	if (rold->to <= rold->from)
828 		diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
829 	else {
830 		diff_output(d3s->diffbuf, "%d", rold->from);
831 		if (rold->to > rold->from+1)
832 			diff_output(d3s->diffbuf, ",%d", rold->to - 1);
833 		diff_output(d3s->diffbuf, "c\n");
834 	}
835 }
836 
837 /*
838  * No difference was reported by diff between file 1 (or 2) and file 3,
839  * and an artificial dummy difference (trange) must be ginned up to
840  * correspond to the change reported in the other file.
841  */
842 static void
843 keep(int i, struct range *rnew, struct diff3_state *d3s)
844 {
845 	int delta;
846 	struct range trange;
847 
848 	delta = d3s->last[3] - d3s->last[i];
849 	trange.from = rnew->from - delta;
850 	trange.to = rnew->to - delta;
851 	change(i, &trange, 1, d3s);
852 }
853 
854 /*
855  * skip to just before line number from in file "i".  If "pr" is non-NULL,
856  * print all skipped stuff with string pr as a prefix.
857  */
858 static int
859 skip(int i, int from, char *pr, struct diff3_state *d3s)
860 {
861 	size_t j, n;
862 	char *line;
863 
864 	for (n = 0; d3s->cline[i] < from - 1; n += j) {
865 		if ((line = get_line(d3s->fp[i], &j, d3s)) == NULL)
866 			return (-1);
867 		if (pr != NULL)
868 			diff_output(d3s->diffbuf, "%s%s", pr, line);
869 		d3s->cline[i]++;
870 	}
871 	return ((int) n);
872 }
873 
874 /*
875  * Return 1 or 0 according as the old range (in file 1) contains exactly
876  * the same data as the new range (in file 2).
877  */
878 static int
879 duplicate(struct range *r1, struct range *r2, struct diff3_state *d3s)
880 {
881 	int c,d;
882 	int nchar;
883 	int nline;
884 
885 	if (r1->to-r1->from != r2->to-r2->from)
886 		return (0);
887 	(void)skip(0, r1->from, NULL, d3s);
888 	(void)skip(1, r2->from, NULL, d3s);
889 	nchar = 0;
890 	for (nline=0; nline < r1->to - r1->from; nline++) {
891 		do {
892 			c = getc(d3s->fp[0]);
893 			d = getc(d3s->fp[1]);
894 			if (c == -1 || d== -1)
895 				return (-1);
896 			nchar++;
897 			if (c != d) {
898 				repos(nchar, d3s);
899 				return (0);
900 			}
901 		} while (c != '\n');
902 	}
903 	repos(nchar, d3s);
904 	return (1);
905 }
906 
907 static void
908 repos(int nchar, struct diff3_state *d3s)
909 {
910 	int i;
911 
912 	for (i = 0; i < 2; i++)
913 		(void)fseek(d3s->fp[i], (long)-nchar, SEEK_CUR);
914 }
915 
916 /*
917  * collect an editing script for later regurgitation
918  */
919 static int
920 edit(struct diff *diff, int fdup, int j, struct diff3_state *d3s)
921 {
922 	if (((fdup + 1) & d3s->eflag) == 0)
923 		return (j);
924 	j++;
925 	d3s->overlap[j] = !fdup;
926 	if (!fdup)
927 		d3s->overlapcnt++;
928 	d3s->de[j].old.from = diff->old.from;
929 	d3s->de[j].old.to = diff->old.to;
930 	d3s->de[j].new.from =
931 	    d3s->de[j-1].new.to + skip(2, diff->new.from, NULL, d3s);
932 	d3s->de[j].new.to =
933 	    d3s->de[j].new.from + skip(2, diff->new.to, NULL, d3s);
934 	return (j);
935 }
936 
937 /* regurgitate */
938 static int
939 edscript(int n, struct diff3_state *d3s)
940 {
941 	int j, k;
942 	char block[BUFSIZ+1];
943 
944 	for (; n > 0; n--) {
945 		if (!d3s->oflag || !d3s->overlap[n])
946 			prange(&d3s->de[n].old, d3s);
947 		else
948 			diff_output(d3s->diffbuf, "%da\n%s\n",
949 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
950 		(void)fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET);
951 		k = d3s->de[n].new.to - d3s->de[n].new.from;
952 		for (; k > 0; k-= j) {
953 			j = k > BUFSIZ ? BUFSIZ : k;
954 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
955 				return (-1);
956 			block[j] = '\0';
957 			diff_output(d3s->diffbuf, "%s", block);
958 		}
959 
960 		if (!d3s->oflag || !d3s->overlap[n])
961 			diff_output(d3s->diffbuf, ".\n");
962 		else {
963 			diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
964 			diff_output(d3s->diffbuf, "%da\n%s\n.\n",
965 			    d3s->de[n].old.from - 1, d3s->f1mark);
966 		}
967 	}
968 
969 	return (d3s->overlapcnt);
970 }
971 
972 static const struct got_error *
973 increase(struct diff3_state *d3s)
974 {
975 	size_t newsz, incr;
976 	struct diff *d;
977 	char *s;
978 
979 	/* are the memset(3) calls needed? */
980 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
981 	incr = newsz - d3s->szchanges;
982 
983 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
984 	if (d == NULL)
985 		return got_error_from_errno("reallocarray");
986 	d3s->d13 = d;
987 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
988 
989 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
990 	if (d == NULL)
991 		return got_error_from_errno("reallocarray");
992 	d3s->d23 = d;
993 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
994 
995 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
996 	if (d == NULL)
997 		return got_error_from_errno("reallocarray");
998 	d3s->de = d;
999 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1000 
1001 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1002 	if (s == NULL)
1003 		return got_error_from_errno("reallocarray");
1004 	d3s->overlap = s;
1005 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1006 	d3s->szchanges = newsz;
1007 
1008 	return NULL;
1009 }