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Date:: Wed Sep 25 20:02:03 2019 UTC
Message:: getline: fix the return type to ssize_t and small nits
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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 debug;
145 	char f1mark[PATH_MAX], f3mark[PATH_MAX]; /* markers for -E and -X */
146 
147 	char *buf;
148 
149 	BUF *diffbuf;
150 };
151 
152 
153 static int duplicate(struct range *, struct range *, struct diff3_state *);
154 static int edit(struct diff *, int, int, struct diff3_state *);
155 static char *getchange(FILE *, struct diff3_state *);
156 static char *get_line(FILE *, size_t *, struct diff3_state *);
157 static int number(char **);
158 static const struct got_error *readin(size_t *, char *, struct diff **,
159     struct diff3_state *);
160 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
161 static int skip(int, int, char *, struct diff3_state *);
162 static int edscript(int, struct diff3_state *);
163 static int merge(size_t, size_t, struct diff3_state *);
164 static void change(int, struct range *, int, struct diff3_state *);
165 static void keep(int, struct range *, struct diff3_state *);
166 static void prange(struct range *, struct diff3_state *);
167 static void repos(int, struct diff3_state *);
168 static void separate(const char *, struct diff3_state *);
169 static const struct got_error *increase(struct diff3_state *);
170 static const struct got_error *diff3_internal(char *, char *, char *,
171     char *, char *, const char *, const char *, struct diff3_state *,
172     const char *, const char *);
173 
174 static const struct got_error *
175 diff_output(BUF *diffbuf, const char *fmt, ...)
176 {
177 	va_list vap;
178 	int i;
179 	char *str;
180 	size_t newsize;
181 
182 	va_start(vap, fmt);
183 	i = vasprintf(&str, fmt, vap);
184 	va_end(vap);
185 	if (i == -1)
186 		return got_error_from_errno("vasprintf");
187 	buf_append(&newsize, diffbuf, str, strlen(str));
188 	free(str);
189 	return NULL;
190 }
191 
192 static const struct got_error*
193 diffreg(BUF **d, const char *path1, const char *path2)
194 {
195 	const struct got_error *err = NULL;
196 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
197 	char *outpath = NULL;
198 	struct got_diff_state ds;
199 	struct got_diff_args args;
200 	int res;
201 
202 	*d = NULL;
203 
204 	f1 = fopen(path1, "r");
205 	if (f1 == NULL) {
206 		err = got_error_from_errno2("fopen", path1);
207 		goto done;
208 	}
209 	f2 = fopen(path2, "r");
210 	if (f1 == NULL) {
211 		err = got_error_from_errno2("fopen", path2);
212 		goto done;
213 	}
214 
215 	err = got_opentemp_named(&outpath, &outfile, "/tmp/got-diffreg");
216 	if (err)
217 		goto done;
218 
219 	memset(&ds, 0, sizeof(ds));
220 	/* XXX should stat buffers be passed in args instead of ds? */
221 	if (stat(path1, &ds.stb1) == -1) {
222 		err = got_error_from_errno2("stat", path1);
223 		goto done;
224 	}
225 	if (stat(path2, &ds.stb2) == -1) {
226 		err = got_error_from_errno2("stat", path2);
227 		goto done;
228 	}
229 
230 	memset(&args, 0, sizeof(args));
231 	args.diff_format = D_NORMAL;
232 	args.label[0] = "";
233 	args.label[1] = "";
234 	args.diff_context = 0;
235 
236 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
237 	    outfile, NULL);
238 	if (err)
239 		goto done;
240 
241 	if (fflush(outfile) != 0) {
242 		err = got_error_from_errno2("fflush", outpath);
243 		goto done;
244 	}
245 
246 	*d = buf_load(outpath);
247 	if (*d == NULL)
248 		err = got_error_from_errno("buf_load");
249 done:
250 	if (outpath) {
251 		unlink(outpath);
252 		free(outpath);
253 	}
254 	if (outfile && fclose(outfile) != 0 && err == NULL)
255 		err = got_error_from_errno("fclose");
256 	if (f1 && fclose(f1) != 0 && err == NULL)
257 		err = got_error_from_errno("fclose");
258 	if (f2 && fclose(f2) != 0 && err == NULL)
259 		err = got_error_from_errno("fclose");
260 	return err;
261 }
262 
263 /*
264  * For merge(1).
265  */
266 const struct got_error *
267 got_merge_diff3(int *overlapcnt, int outfd, const char *p1, const char *p2,
268     const char *p3, const char *label1, const char *label3)
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 	*overlapcnt = 0;
280 
281 	SLIST_INIT(&temp_files);
282 
283 	d3s = calloc(1, sizeof(*d3s));
284 	if (d3s == NULL)
285 		return got_error_from_errno("calloc");
286 	d3s->eflag = 3; /* default -E for compatibility with former RCS */
287 
288 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
289 	dp13 = dp23 = path1 = path2 = path3 = NULL;
290 	data = patch = NULL;
291 
292 	if ((b1 = buf_load(p1)) == NULL)
293 		goto out;
294 	if ((b2 = buf_load(p2)) == NULL)
295 		goto out;
296 	if ((b3 = buf_load(p3)) == NULL)
297 		goto out;
298 
299 	diffb = buf_alloc(128);
300 
301 	if (asprintf(&path1, "/tmp/got-diff1.XXXXXXXX") == -1) {
302 		err = got_error_from_errno("asprintf");
303 		goto out;
304 	}
305 	if (asprintf(&path2, "/tmp/got-diff2.XXXXXXXX") == -1) {
306 		err = got_error_from_errno("asprintf");
307 		goto out;
308 	}
309 	if (asprintf(&path3, "/tmp/got-diff3.XXXXXXXX") == -1) {
310 		err = got_error_from_errno("asprintf");
311 		goto out;
312 	}
313 
314 	err = buf_write_stmp(b1, path1, &temp_files);
315 	if (err)
316 		goto out;
317 	err = buf_write_stmp(b2, path2, &temp_files);
318 	if (err)
319 		goto out;
320 	err = buf_write_stmp(b3, path3, &temp_files);
321 	if (err)
322 		goto out;
323 
324 	buf_free(b2);
325 	b2 = NULL;
326 
327 	err = diffreg(&d1, path1, path3);
328 	if (err) {
329 		buf_free(diffb);
330 		diffb = NULL;
331 		goto out;
332 
333 	}
334 	err = diffreg(&d2, path2, path3);
335 	if (err) {
336 		buf_free(diffb);
337 		diffb = NULL;
338 		goto out;
339 	}
340 
341 	if (asprintf(&dp13, "/tmp/got-d13.XXXXXXXXXX") == -1) {
342 		err = got_error_from_errno("asprintf");
343 		goto out;
344 	}
345 	err = buf_write_stmp(d1, dp13, &temp_files);
346 	if (err)
347 		goto out;
348 
349 	buf_free(d1);
350 	d1 = NULL;
351 
352 	if (asprintf(&dp23, "/tmp/got-d23.XXXXXXXXXX") == -1) {
353 		err = got_error_from_errno("asprintf");
354 		goto out;
355 	}
356 	err = buf_write_stmp(d2, dp23, &temp_files);
357 	if (err)
358 		goto out;
359 
360 	buf_free(d2);
361 	d2 = NULL;
362 
363 	d3s->diffbuf = diffb;
364 	err = diff3_internal(dp13, dp23, path1, path2, path3,
365 	    label1, label3, d3s, label1, label3);
366 	if (err) {
367 		buf_free(diffb);
368 		diffb = NULL;
369 		goto out;
370 	}
371 
372 	plen = buf_len(diffb);
373 	patch = buf_release(diffb);
374 	dlen = buf_len(b1);
375 	data = buf_release(b1);
376 
377 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
378 out:
379 	buf_free(b2);
380 	buf_free(b3);
381 	buf_free(d1);
382 	buf_free(d2);
383 
384 	(void)unlink(path1);
385 	(void)unlink(path2);
386 	(void)unlink(path3);
387 	(void)unlink(dp13);
388 	(void)unlink(dp23);
389 
390 	free(path1);
391 	free(path2);
392 	free(path3);
393 	free(dp13);
394 	free(dp23);
395 	free(data);
396 	free(patch);
397 
398 	worklist_clean(&temp_files, worklist_unlink);
399 
400 	for (i = 0; i < nitems(d3s->fp); i++) {
401 		if (d3s->fp[i] && fclose(d3s->fp[i]) != 0 && err == NULL)
402 			err = got_error_from_errno("fclose");
403 	}
404 	if (err == NULL && diffb) {
405 		if (buf_write_fd(diffb, outfd) < 0)
406 			err = got_error_from_errno("buf_write_fd");
407 		*overlapcnt = d3s->overlapcnt;
408 	}
409 	free(d3s);
410 	buf_free(diffb);
411 	return err;
412 }
413 
414 static const struct got_error *
415 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
416     const char *fmark, const char *rmark, struct diff3_state *d3s,
417     const char *label1, const char *label3)
418 {
419 	const struct got_error *err = NULL;
420 	ssize_t m, n;
421 	int i;
422 
423 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
424 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_BEGIN, label1);
425 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
426 		return got_error(GOT_ERR_NO_SPACE);
427 
428 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
429 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_END, label3);
430 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
431 		return got_error(GOT_ERR_NO_SPACE);
432 
433 	err = increase(d3s);
434 	if (err)
435 		return err;
436 
437 	err = readin(&m, dp13, &d3s->d13, d3s);
438 	if (err)
439 		return err;
440 	err = readin(&n, dp23, &d3s->d23, d3s);
441 	if (err)
442 		return err;
443 
444 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
445 		return got_error_from_errno2("fopen", path1);
446 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
447 		return got_error_from_errno2("fopen", path2);
448 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
449 		return got_error_from_errno2("fopen", path3);
450 
451 	if (merge(m, n, d3s) < 0)
452 		return got_error_from_errno("merge");
453 	return NULL;
454 }
455 
456 static int
457 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
458 {
459 	char op, *ep;
460 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
461 	int start, end, i, lineno;
462 	u_char tmp;
463 
464 	dlp = TAILQ_FIRST(&(dlines->l_lines));
465 	lp = TAILQ_FIRST(&(plines->l_lines));
466 
467 	end = 0;
468 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
469 	    lp = TAILQ_NEXT(lp, l_list)) {
470 		/* Skip blank lines */
471 		if (lp->l_len < 2)
472 			continue;
473 
474 		/* NUL-terminate line buffer for strtol() safety. */
475 		tmp = lp->l_line[lp->l_len - 1];
476 		lp->l_line[lp->l_len - 1] = '\0';
477 
478 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
479 		op = lp->l_line[lp->l_len - 2];
480 		start = (int)strtol(lp->l_line, &ep, 10);
481 
482 		/* Restore the last byte of the buffer */
483 		lp->l_line[lp->l_len - 1] = tmp;
484 
485 		if (op == 'a') {
486 			if (start > dlines->l_nblines ||
487 			    start < 0 || *ep != 'a')
488 				return -1;
489 		} else if (op == 'c') {
490 			if (start > dlines->l_nblines ||
491 			    start < 0 || (*ep != ',' && *ep != 'c'))
492 				return -1;
493 
494 			if (*ep == ',') {
495 				ep++;
496 				end = (int)strtol(ep, &ep, 10);
497 				if (end < 0 || *ep != 'c')
498 					return -1;
499 			} else {
500 				end = start;
501 			}
502 		}
503 
504 
505 		for (;;) {
506 			if (dlp == NULL)
507 				break;
508 			if (dlp->l_lineno == start)
509 				break;
510 			if (dlp->l_lineno > start) {
511 				dlp = TAILQ_PREV(dlp, tqh, l_list);
512 			} else if (dlp->l_lineno < start) {
513 				ndlp = TAILQ_NEXT(dlp, l_list);
514 				if (ndlp->l_lineno > start)
515 					break;
516 				dlp = ndlp;
517 			}
518 		}
519 
520 		if (dlp == NULL)
521 			return -1;
522 
523 
524 		if (op == 'c') {
525 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
526 			for (i = 0; i <= (end - start); i++) {
527 				ndlp = TAILQ_NEXT(dlp, l_list);
528 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
529 				dlp = ndlp;
530 			}
531 			dlp = insert_after;
532 		}
533 
534 		if (op == 'a' || op == 'c') {
535 			for (;;) {
536 				ndlp = lp;
537 				lp = TAILQ_NEXT(lp, l_list);
538 				if (lp == NULL)
539 					return -1;
540 
541 				if (lp->l_len == 2 &&
542 				    lp->l_line[0] == '.' &&
543 				    lp->l_line[1] == '\n')
544 					break;
545 
546 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
547 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
548 				    lp, l_list);
549 				dlp = lp;
550 
551 				lp->l_lineno = start;
552 				lp = ndlp;
553 			}
554 		}
555 
556 		/*
557 		 * always resort lines as the markers might be put at the
558 		 * same line as we first started editing.
559 		 */
560 		lineno = 0;
561 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
562 			sort->l_lineno = lineno++;
563 		dlines->l_nblines = lineno - 1;
564 	}
565 
566 	return (0);
567 }
568 
569 /*
570  * Pick up the line numbers of all changes from one change file.
571  * (This puts the numbers in a vector, which is not strictly necessary,
572  * since the vector is processed in one sequential pass.
573  * The vector could be optimized out of existence)
574  */
575 static const struct got_error *
576 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
577 {
578 	const struct got_error *err = NULL;
579 	int a, b, c, d;
580 	char kind, *p;
581 	size_t i;
582 
583 	*n = 0;
584 
585 	d3s->fp[0] = fopen(name, "r");
586 	if (d3s->fp[0] == NULL)
587 		return got_error_from_errno2("fopen", name);
588 	for (i = 0; (p = getchange(d3s->fp[0], d3s)); i++) {
589 		if (i >= d3s->szchanges - 1) {
590 			err = increase(d3s);
591 			if (err)
592 				return err;
593 		}
594 		a = b = number(&p);
595 		if (*p == ',') {
596 			p++;
597 			b = number(&p);
598 		}
599 		kind = *p++;
600 		c = d = number(&p);
601 		if (*p==',') {
602 			p++;
603 			d = number(&p);
604 		}
605 		if (kind == 'a')
606 			a++;
607 		if (kind == 'd')
608 			c++;
609 		b++;
610 		d++;
611 		(*dd)[i].old.from = a;
612 		(*dd)[i].old.to = b;
613 		(*dd)[i].new.from = c;
614 		(*dd)[i].new.to = d;
615 	}
616 
617 	if (i) {
618 		(*dd)[i].old.from = (*dd)[i-1].old.to;
619 		(*dd)[i].new.from = (*dd)[i-1].new.to;
620 	}
621 
622 	if (fclose(d3s->fp[0]) != 0)
623 		err = got_error_from_errno("fclose");
624 
625 	*n = i;
626 	return err;
627 }
628 
629 static int
630 number(char **lc)
631 {
632 	int nn;
633 
634 	nn = 0;
635 	while (isdigit((unsigned char)(**lc)))
636 		nn = nn*10 + *(*lc)++ - '0';
637 
638 	return (nn);
639 }
640 
641 static char *
642 getchange(FILE *b, struct diff3_state *d3s)
643 {
644 	char *line;
645 
646 	while ((line = get_line(b, NULL, d3s))) {
647 		if (isdigit((unsigned char)line[0]))
648 			return (line);
649 	}
650 
651 	return (NULL);
652 }
653 
654 static char *
655 get_line(FILE *b, size_t *n, struct diff3_state *d3s)
656 {
657 	char *cp = NULL;
658 	size_t size;
659 	ssize_t len;
660 	char *new;
661 	char *ret = NULL;
662 
663 	len = getline(&cp, &size, b);
664 	if (len == -1)
665 		goto done;
666 
667 	if (cp[len - 1] != '\n') {
668 		len++;
669 		if (len + 1 > size) {
670 			new = realloc(cp, len + 1);
671 			if (new == NULL)
672 				goto done;
673 			cp = new;
674 		}
675 		cp[len - 1] = '\n';
676 		cp[len] = '\0';
677 	}
678 
679 	free(d3s->buf);
680 	ret = d3s->buf = cp;
681 	cp = NULL;
682 	if (n != NULL)
683 		*n = len;
684 done:
685 	free(cp);
686 	return (ret);
687 }
688 
689 static int
690 merge(size_t m1, size_t m2, struct diff3_state *d3s)
691 {
692 	struct diff *d1, *d2, *d3;
693 	int dpl, j, t1, t2;
694 
695 	d1 = d3s->d13;
696 	d2 = d3s->d23;
697 	j = 0;
698 	for (;;) {
699 		t1 = (d1 < d3s->d13 + m1);
700 		t2 = (d2 < d3s->d23 + m2);
701 		if (!t1 && !t2)
702 			break;
703 
704 		if (d3s->debug) {
705 			printf("%d,%d=%d,%d %d,%d=%d,%d\n",
706 			d1->old.from, d1->old.to,
707 			d1->new.from, d1->new.to,
708 			d2->old.from, d2->old.to,
709 			d2->new.from, d2->new.to);
710 		}
711 
712 		/* first file is different from others */
713 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
714 			/* stuff peculiar to 1st file */
715 			if (d3s->eflag == 0) {
716 				separate("1", d3s);
717 				change(1, &d1->old, 0, d3s);
718 				keep(2, &d1->new, d3s);
719 				change(3, &d1->new, 0, d3s);
720 			}
721 			d1++;
722 			continue;
723 		}
724 
725 		/* second file is different from others */
726 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
727 			if (d3s->eflag == 0) {
728 				separate("2", d3s);
729 				keep(1, &d2->new, d3s);
730 				change(2, &d2->old, 0, d3s);
731 				change(3, &d2->new, 0, d3s);
732 			}
733 			d2++;
734 			continue;
735 		}
736 
737 		/*
738 		 * Merge overlapping changes in first file
739 		 * this happens after extension (see below).
740 		 */
741 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
742 			d1[1].old.from = d1->old.from;
743 			d1[1].new.from = d1->new.from;
744 			d1++;
745 			continue;
746 		}
747 
748 		/* merge overlapping changes in second */
749 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
750 			d2[1].old.from = d2->old.from;
751 			d2[1].new.from = d2->new.from;
752 			d2++;
753 			continue;
754 		}
755 		/* stuff peculiar to third file or different in all */
756 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
757 			dpl = duplicate(&d1->old, &d2->old, d3s);
758 			if (dpl == -1)
759 				return (-1);
760 
761 			/*
762 			 * dpl = 0 means all files differ
763 			 * dpl = 1 means files 1 and 2 identical
764 			 */
765 			if (d3s->eflag == 0) {
766 				separate(dpl ? "3" : "", d3s);
767 				change(1, &d1->old, dpl, d3s);
768 				change(2, &d2->old, 0, d3s);
769 				d3 = d1->old.to > d1->old.from ? d1 : d2;
770 				change(3, &d3->new, 0, d3s);
771 			} else
772 				j = edit(d1, dpl, j, d3s);
773 			d1++;
774 			d2++;
775 			continue;
776 		}
777 
778 		/*
779 		 * Overlapping changes from file 1 and 2; extend changes
780 		 * appropriately to make them coincide.
781 		 */
782 		if (d1->new.from < d2->new.from) {
783 			d2->old.from -= d2->new.from-d1->new.from;
784 			d2->new.from = d1->new.from;
785 		} else if (d2->new.from < d1->new.from) {
786 			d1->old.from -= d1->new.from-d2->new.from;
787 			d1->new.from = d2->new.from;
788 		}
789 		if (d1->new.to > d2->new.to) {
790 			d2->old.to += d1->new.to - d2->new.to;
791 			d2->new.to = d1->new.to;
792 		} else if (d2->new.to > d1->new.to) {
793 			d1->old.to += d2->new.to - d1->new.to;
794 			d1->new.to = d2->new.to;
795 		}
796 	}
797 
798 	return (edscript(j, d3s));
799 }
800 
801 static void
802 separate(const char *s, struct diff3_state *d3s)
803 {
804 	diff_output(d3s->diffbuf, "====%s\n", s);
805 }
806 
807 /*
808  * The range of lines rold.from thru rold.to in file i is to be changed.
809  * It is to be printed only if it does not duplicate something to be
810  * printed later.
811  */
812 static void
813 change(int i, struct range *rold, int fdup, struct diff3_state *d3s)
814 {
815 	diff_output(d3s->diffbuf, "%d:", i);
816 	d3s->last[i] = rold->to;
817 	prange(rold, d3s);
818 	if (fdup || d3s->debug)
819 		return;
820 	i--;
821 	(void)skip(i, rold->from, NULL, d3s);
822 	(void)skip(i, rold->to, "  ", d3s);
823 }
824 
825 /*
826  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
827  */
828 static void
829 prange(struct range *rold, struct diff3_state *d3s)
830 {
831 	if (rold->to <= rold->from)
832 		diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
833 	else {
834 		diff_output(d3s->diffbuf, "%d", rold->from);
835 		if (rold->to > rold->from+1)
836 			diff_output(d3s->diffbuf, ",%d", rold->to - 1);
837 		diff_output(d3s->diffbuf, "c\n");
838 	}
839 }
840 
841 /*
842  * No difference was reported by diff between file 1 (or 2) and file 3,
843  * and an artificial dummy difference (trange) must be ginned up to
844  * correspond to the change reported in the other file.
845  */
846 static void
847 keep(int i, struct range *rnew, struct diff3_state *d3s)
848 {
849 	int delta;
850 	struct range trange;
851 
852 	delta = d3s->last[3] - d3s->last[i];
853 	trange.from = rnew->from - delta;
854 	trange.to = rnew->to - delta;
855 	change(i, &trange, 1, d3s);
856 }
857 
858 /*
859  * skip to just before line number from in file "i".  If "pr" is non-NULL,
860  * print all skipped stuff with string pr as a prefix.
861  */
862 static int
863 skip(int i, int from, char *pr, struct diff3_state *d3s)
864 {
865 	size_t j, n;
866 	char *line;
867 
868 	for (n = 0; d3s->cline[i] < from - 1; n += j) {
869 		if ((line = get_line(d3s->fp[i], &j, d3s)) == NULL)
870 			return (-1);
871 		if (pr != NULL)
872 			diff_output(d3s->diffbuf, "%s%s", pr, line);
873 		d3s->cline[i]++;
874 	}
875 	return ((int) n);
876 }
877 
878 /*
879  * Return 1 or 0 according as the old range (in file 1) contains exactly
880  * the same data as the new range (in file 2).
881  */
882 static int
883 duplicate(struct range *r1, struct range *r2, struct diff3_state *d3s)
884 {
885 	int c,d;
886 	int nchar;
887 	int nline;
888 
889 	if (r1->to-r1->from != r2->to-r2->from)
890 		return (0);
891 	(void)skip(0, r1->from, NULL, d3s);
892 	(void)skip(1, r2->from, NULL, d3s);
893 	nchar = 0;
894 	for (nline=0; nline < r1->to - r1->from; nline++) {
895 		do {
896 			c = getc(d3s->fp[0]);
897 			d = getc(d3s->fp[1]);
898 			if (c == -1 || d== -1)
899 				return (-1);
900 			nchar++;
901 			if (c != d) {
902 				repos(nchar, d3s);
903 				return (0);
904 			}
905 		} while (c != '\n');
906 	}
907 	repos(nchar, d3s);
908 	return (1);
909 }
910 
911 static void
912 repos(int nchar, struct diff3_state *d3s)
913 {
914 	int i;
915 
916 	for (i = 0; i < 2; i++)
917 		(void)fseek(d3s->fp[i], (long)-nchar, SEEK_CUR);
918 }
919 
920 /*
921  * collect an editing script for later regurgitation
922  */
923 static int
924 edit(struct diff *diff, int fdup, int j, struct diff3_state *d3s)
925 {
926 	if (((fdup + 1) & d3s->eflag) == 0)
927 		return (j);
928 	j++;
929 	d3s->overlap[j] = !fdup;
930 	if (!fdup)
931 		d3s->overlapcnt++;
932 	d3s->de[j].old.from = diff->old.from;
933 	d3s->de[j].old.to = diff->old.to;
934 	d3s->de[j].new.from =
935 	    d3s->de[j-1].new.to + skip(2, diff->new.from, NULL, d3s);
936 	d3s->de[j].new.to =
937 	    d3s->de[j].new.from + skip(2, diff->new.to, NULL, d3s);
938 	return (j);
939 }
940 
941 /* regurgitate */
942 static int
943 edscript(int n, struct diff3_state *d3s)
944 {
945 	int j, k;
946 	char block[BUFSIZ+1];
947 
948 	for (; n > 0; n--) {
949 		if (!d3s->overlap[n])
950 			prange(&d3s->de[n].old, d3s);
951 		else
952 			diff_output(d3s->diffbuf, "%da\n%s\n",
953 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
954 		(void)fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET);
955 		k = d3s->de[n].new.to - d3s->de[n].new.from;
956 		for (; k > 0; k-= j) {
957 			j = k > BUFSIZ ? BUFSIZ : k;
958 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
959 				return (-1);
960 			block[j] = '\0';
961 			diff_output(d3s->diffbuf, "%s", block);
962 		}
963 
964 		if (!d3s->overlap[n])
965 			diff_output(d3s->diffbuf, ".\n");
966 		else {
967 			diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
968 			diff_output(d3s->diffbuf, "%da\n%s\n.\n",
969 			    d3s->de[n].old.from - 1, d3s->f1mark);
970 		}
971 	}
972 
973 	return (d3s->overlapcnt);
974 }
975 
976 static const struct got_error *
977 increase(struct diff3_state *d3s)
978 {
979 	size_t newsz, incr;
980 	struct diff *d;
981 	char *s;
982 
983 	/* are the memset(3) calls needed? */
984 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
985 	incr = newsz - d3s->szchanges;
986 
987 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
988 	if (d == NULL)
989 		return got_error_from_errno("reallocarray");
990 	d3s->d13 = d;
991 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
992 
993 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
994 	if (d == NULL)
995 		return got_error_from_errno("reallocarray");
996 	d3s->d23 = d;
997 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
998 
999 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1000 	if (d == NULL)
1001 		return got_error_from_errno("reallocarray");
1002 	d3s->de = d;
1003 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1004 
1005 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1006 	if (s == NULL)
1007 		return got_error_from_errno("reallocarray");
1008 	d3s->overlap = s;
1009 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1010 	d3s->szchanges = newsz;
1011 
1012 	return NULL;
1013 }