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Date:: Wed Oct 9 07:57:27 2019 UTC
Message:: rename local variable in diff3.c's skip() from j to len (not a loop index)
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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 	char f1mark[PATH_MAX], f3mark[PATH_MAX]; /* markers for -E and -X */
144 
145 	char *buf;
146 
147 	BUF *diffbuf;
148 };
149 
150 
151 static const struct got_error *duplicate(int *, struct range *, struct range *,
152     struct diff3_state *);
153 static const struct got_error *edit(struct diff *, int, int *,
154     struct diff3_state *);
155 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
156 static const struct got_error *get_line(char **, FILE *, size_t *,
157     struct diff3_state *);
158 static int number(char **);
159 static const struct got_error *readin(size_t *, char *, struct diff **,
160     struct diff3_state *);
161 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
162 static const struct got_error *skip(int *, int, int, struct diff3_state *);
163 static const struct got_error *edscript(int, struct diff3_state *);
164 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
165 static const struct got_error *prange(struct range *, struct diff3_state *);
166 static const struct got_error *repos(int, struct diff3_state *);
167 static const struct got_error *increase(struct diff3_state *);
168 static const struct got_error *diff3_internal(char *, char *, char *,
169     char *, char *, const char *, const char *, struct diff3_state *,
170     const char *, const char *);
171 
172 static const struct got_error *
173 diff_output(BUF *diffbuf, const char *fmt, ...)
174 {
175 	const struct got_error *err = NULL;
176 	va_list vap;
177 	int i;
178 	char *str;
179 	size_t newsize;
180 
181 	va_start(vap, fmt);
182 	i = vasprintf(&str, fmt, vap);
183 	va_end(vap);
184 	if (i == -1)
185 		return got_error_from_errno("vasprintf");
186 	err = buf_append(&newsize, diffbuf, str, strlen(str));
187 	free(str);
188 	return err;
189 }
190 
191 static const struct got_error*
192 diffreg(BUF **d, const char *path1, const char *path2)
193 {
194 	const struct got_error *err = NULL;
195 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
196 	char *outpath = NULL;
197 	struct got_diff_state ds;
198 	struct got_diff_args args;
199 	int res;
200 
201 	*d = NULL;
202 
203 	f1 = fopen(path1, "r");
204 	if (f1 == NULL) {
205 		err = got_error_from_errno2("fopen", path1);
206 		goto done;
207 	}
208 	f2 = fopen(path2, "r");
209 	if (f1 == NULL) {
210 		err = got_error_from_errno2("fopen", path2);
211 		goto done;
212 	}
213 
214 	err = got_opentemp_named(&outpath, &outfile, "/tmp/got-diffreg");
215 	if (err)
216 		goto done;
217 
218 	memset(&ds, 0, sizeof(ds));
219 	/* XXX should stat buffers be passed in args instead of ds? */
220 	if (stat(path1, &ds.stb1) == -1) {
221 		err = got_error_from_errno2("stat", path1);
222 		goto done;
223 	}
224 	if (stat(path2, &ds.stb2) == -1) {
225 		err = got_error_from_errno2("stat", path2);
226 		goto done;
227 	}
228 
229 	memset(&args, 0, sizeof(args));
230 	args.diff_format = D_NORMAL;
231 	args.label[0] = "";
232 	args.label[1] = "";
233 	args.diff_context = 0;
234 
235 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
236 	    outfile, NULL);
237 	if (err)
238 		goto done;
239 
240 	if (fflush(outfile) != 0) {
241 		err = got_error_from_errno2("fflush", outpath);
242 		goto done;
243 	}
244 
245 	err = buf_load(d, outpath);
246 done:
247 	if (outpath) {
248 		unlink(outpath);
249 		free(outpath);
250 	}
251 	if (outfile && fclose(outfile) != 0 && err == NULL)
252 		err = got_error_from_errno("fclose");
253 	if (f1 && fclose(f1) != 0 && err == NULL)
254 		err = got_error_from_errno("fclose");
255 	if (f2 && fclose(f2) != 0 && err == NULL)
256 		err = got_error_from_errno("fclose");
257 	return err;
258 }
259 
260 /*
261  * For merge(1).
262  */
263 const struct got_error *
264 got_merge_diff3(int *overlapcnt, int outfd, const char *p1, const char *p2,
265     const char *p3, const char *label1, const char *label3)
266 {
267 	const struct got_error *err = NULL;
268 	char *dp13, *dp23, *path1, *path2, *path3;
269 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
270 	u_char *data, *patch;
271 	size_t dlen, plen;
272 	struct wklhead temp_files;
273 	struct diff3_state *d3s;
274 	int i;
275 
276 	*overlapcnt = 0;
277 
278 	SLIST_INIT(&temp_files);
279 
280 	d3s = calloc(1, sizeof(*d3s));
281 	if (d3s == NULL)
282 		return got_error_from_errno("calloc");
283 
284 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
285 	dp13 = dp23 = path1 = path2 = path3 = NULL;
286 	data = patch = NULL;
287 
288 	err = buf_load(&b1, p1);
289 	if (err)
290 		goto out;
291 	err = buf_load(&b2, p2);
292 	if (err)
293 		goto out;
294 	err = buf_load(&b3, p3);
295 	if (err)
296 		goto out;
297 
298 	err = buf_alloc(&diffb, 128);
299 	if (err)
300 		goto out;
301 
302 	if (asprintf(&path1, "/tmp/got-diff1.XXXXXXXX") == -1) {
303 		err = got_error_from_errno("asprintf");
304 		goto out;
305 	}
306 	if (asprintf(&path2, "/tmp/got-diff2.XXXXXXXX") == -1) {
307 		err = got_error_from_errno("asprintf");
308 		goto out;
309 	}
310 	if (asprintf(&path3, "/tmp/got-diff3.XXXXXXXX") == -1) {
311 		err = got_error_from_errno("asprintf");
312 		goto out;
313 	}
314 
315 	err = buf_write_stmp(b1, path1, &temp_files);
316 	if (err)
317 		goto out;
318 	err = buf_write_stmp(b2, path2, &temp_files);
319 	if (err)
320 		goto out;
321 	err = buf_write_stmp(b3, path3, &temp_files);
322 	if (err)
323 		goto out;
324 
325 	buf_free(b2);
326 	b2 = NULL;
327 
328 	err = diffreg(&d1, path1, path3);
329 	if (err) {
330 		buf_free(diffb);
331 		diffb = NULL;
332 		goto out;
333 
334 	}
335 	err = diffreg(&d2, path2, path3);
336 	if (err) {
337 		buf_free(diffb);
338 		diffb = NULL;
339 		goto out;
340 	}
341 
342 	if (asprintf(&dp13, "/tmp/got-d13.XXXXXXXXXX") == -1) {
343 		err = got_error_from_errno("asprintf");
344 		goto out;
345 	}
346 	err = buf_write_stmp(d1, dp13, &temp_files);
347 	if (err)
348 		goto out;
349 
350 	buf_free(d1);
351 	d1 = NULL;
352 
353 	if (asprintf(&dp23, "/tmp/got-d23.XXXXXXXXXX") == -1) {
354 		err = got_error_from_errno("asprintf");
355 		goto out;
356 	}
357 	err = buf_write_stmp(d2, dp23, &temp_files);
358 	if (err)
359 		goto out;
360 
361 	buf_free(d2);
362 	d2 = NULL;
363 
364 	d3s->diffbuf = diffb;
365 	err = diff3_internal(dp13, dp23, path1, path2, path3,
366 	    label1, label3, d3s, label1, label3);
367 	if (err) {
368 		buf_free(diffb);
369 		diffb = NULL;
370 		goto out;
371 	}
372 
373 	plen = buf_len(diffb);
374 	patch = buf_release(diffb);
375 	dlen = buf_len(b1);
376 	data = buf_release(b1);
377 
378 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
379 out:
380 	buf_free(b2);
381 	buf_free(b3);
382 	buf_free(d1);
383 	buf_free(d2);
384 
385 	(void)unlink(path1);
386 	(void)unlink(path2);
387 	(void)unlink(path3);
388 
389 	free(path1);
390 	free(path2);
391 	free(path3);
392 	free(dp13);
393 	free(dp23);
394 	free(data);
395 	free(patch);
396 
397 	worklist_clean(&temp_files, worklist_unlink);
398 
399 	for (i = 0; i < nitems(d3s->fp); i++) {
400 		if (d3s->fp[i] && fclose(d3s->fp[i]) != 0 && err == NULL)
401 			err = got_error_from_errno("fclose");
402 	}
403 	if (err == NULL && diffb) {
404 		if (buf_write_fd(diffb, outfd) < 0)
405 			err = got_error_from_errno("buf_write_fd");
406 		*overlapcnt = d3s->overlapcnt;
407 	}
408 	free(d3s);
409 	buf_free(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     const char *label1, const char *label3)
417 {
418 	const struct got_error *err = NULL;
419 	ssize_t m, n;
420 	int i;
421 
422 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
423 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_BEGIN, label1);
424 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
425 		return got_error(GOT_ERR_NO_SPACE);
426 
427 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
428 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_END, label3);
429 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
430 		return got_error(GOT_ERR_NO_SPACE);
431 
432 	err = increase(d3s);
433 	if (err)
434 		return err;
435 
436 	err = readin(&m, dp13, &d3s->d13, d3s);
437 	if (err)
438 		return err;
439 	err = readin(&n, dp23, &d3s->d23, d3s);
440 	if (err)
441 		return err;
442 
443 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
444 		return got_error_from_errno2("fopen", path1);
445 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
446 		return got_error_from_errno2("fopen", path2);
447 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
448 		return got_error_from_errno2("fopen", path3);
449 
450 	return merge(m, n, d3s);
451 }
452 
453 static int
454 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
455 {
456 	char op, *ep;
457 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
458 	int start, end, i, lineno;
459 	u_char tmp;
460 
461 	dlp = TAILQ_FIRST(&(dlines->l_lines));
462 	lp = TAILQ_FIRST(&(plines->l_lines));
463 
464 	end = 0;
465 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
466 	    lp = TAILQ_NEXT(lp, l_list)) {
467 		/* Skip blank lines */
468 		if (lp->l_len < 2)
469 			continue;
470 
471 		/* NUL-terminate line buffer for strtol() safety. */
472 		tmp = lp->l_line[lp->l_len - 1];
473 		lp->l_line[lp->l_len - 1] = '\0';
474 
475 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
476 		op = lp->l_line[lp->l_len - 2];
477 		start = (int)strtol(lp->l_line, &ep, 10);
478 
479 		/* Restore the last byte of the buffer */
480 		lp->l_line[lp->l_len - 1] = tmp;
481 
482 		if (op == 'a') {
483 			if (start > dlines->l_nblines ||
484 			    start < 0 || *ep != 'a')
485 				return -1;
486 		} else if (op == 'c') {
487 			if (start > dlines->l_nblines ||
488 			    start < 0 || (*ep != ',' && *ep != 'c'))
489 				return -1;
490 
491 			if (*ep == ',') {
492 				ep++;
493 				end = (int)strtol(ep, &ep, 10);
494 				if (end < 0 || *ep != 'c')
495 					return -1;
496 			} else {
497 				end = start;
498 			}
499 		}
500 
501 
502 		for (;;) {
503 			if (dlp == NULL)
504 				break;
505 			if (dlp->l_lineno == start)
506 				break;
507 			if (dlp->l_lineno > start) {
508 				dlp = TAILQ_PREV(dlp, tqh, l_list);
509 			} else if (dlp->l_lineno < start) {
510 				ndlp = TAILQ_NEXT(dlp, l_list);
511 				if (ndlp->l_lineno > start)
512 					break;
513 				dlp = ndlp;
514 			}
515 		}
516 
517 		if (dlp == NULL)
518 			return -1;
519 
520 
521 		if (op == 'c') {
522 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
523 			for (i = 0; i <= (end - start); i++) {
524 				ndlp = TAILQ_NEXT(dlp, l_list);
525 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
526 				dlp = ndlp;
527 			}
528 			dlp = insert_after;
529 		}
530 
531 		if (op == 'a' || op == 'c') {
532 			for (;;) {
533 				ndlp = lp;
534 				lp = TAILQ_NEXT(lp, l_list);
535 				if (lp == NULL)
536 					return -1;
537 
538 				if (lp->l_len == 2 &&
539 				    lp->l_line[0] == '.' &&
540 				    lp->l_line[1] == '\n')
541 					break;
542 
543 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
544 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
545 				    lp, l_list);
546 				dlp = lp;
547 
548 				lp->l_lineno = start;
549 				lp = ndlp;
550 			}
551 		}
552 
553 		/*
554 		 * always resort lines as the markers might be put at the
555 		 * same line as we first started editing.
556 		 */
557 		lineno = 0;
558 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
559 			sort->l_lineno = lineno++;
560 		dlines->l_nblines = lineno - 1;
561 	}
562 
563 	return (0);
564 }
565 
566 /*
567  * Pick up the line numbers of all changes from one change file.
568  * (This puts the numbers in a vector, which is not strictly necessary,
569  * since the vector is processed in one sequential pass.
570  * The vector could be optimized out of existence)
571  */
572 static const struct got_error *
573 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
574 {
575 	const struct got_error *err = NULL;
576 	FILE *f;
577 	int a, b, c, d;
578 	char kind, *p;
579 	size_t i;
580 
581 	*n = 0;
582 
583 	f = fopen(name, "r");
584 	if (f == NULL)
585 		return got_error_from_errno2("fopen", name);
586 	err = getchange(&p, f, d3s);
587 	if (err)
588 		goto done;
589 	for (i = 0; p; i++) {
590 		if (i >= d3s->szchanges - 1) {
591 			err = increase(d3s);
592 			if (err)
593 				goto done;
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 		err = getchange(&p, f, d3s);
618 		if (err)
619 			goto done;
620 	}
621 
622 	if (i) {
623 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
624 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
625 	}
626 done:
627 	if (fclose(f) != 0 && err == NULL)
628 		err = got_error_from_errno("fclose");
629 	if (err == NULL)
630 		*n = i;
631 	return err;
632 }
633 
634 static int
635 number(char **lc)
636 {
637 	int nn;
638 
639 	nn = 0;
640 	while (isdigit((unsigned char)(**lc)))
641 		nn = nn*10 + *(*lc)++ - '0';
642 
643 	return (nn);
644 }
645 
646 static const struct got_error *
647 getchange(char **line, FILE *b, struct diff3_state *d3s)
648 {
649 	const struct got_error *err = NULL;
650 
651 	*line = NULL;
652 	do {
653 		if (*line && isdigit((unsigned char)(*line)[0]))
654 			return NULL;
655 		err = get_line(line, b, NULL, d3s);
656 		if (err)
657 			return err;
658 	} while (*line);
659 
660 	return NULL;
661 }
662 
663 static const struct got_error *
664 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
665 {
666 	const struct got_error *err = NULL;
667 	char *cp = NULL;
668 	size_t size;
669 	ssize_t len;
670 	char *new;
671 
672 	*ret = NULL;
673 
674 	len = getline(&cp, &size, b);
675 	if (len == -1) {
676 		if (ferror(b))
677 			err = got_error_from_errno("getline");
678 		goto done;
679 	}
680 
681 	if (cp[len - 1] != '\n') {
682 		len++;
683 		if (len + 1 > size) {
684 			new = realloc(cp, len + 1);
685 			if (new == NULL) {
686 				err = got_error_from_errno("realloc");
687 				goto done;
688 			}
689 			cp = new;
690 		}
691 		cp[len - 1] = '\n';
692 		cp[len] = '\0';
693 	}
694 
695 	free(d3s->buf);
696 	*ret = d3s->buf = cp;
697 	cp = NULL;
698 	if (n != NULL)
699 		*n = len;
700 done:
701 	free(cp);
702 	return err;
703 }
704 
705 static const struct got_error *
706 merge(size_t m1, size_t m2, struct diff3_state *d3s)
707 {
708 	const struct got_error *err = NULL;
709 	struct diff *d1, *d2;
710 	int dpl, j, t1, t2;
711 
712 	d1 = d3s->d13;
713 	d2 = d3s->d23;
714 	j = 0;
715 	for (;;) {
716 		t1 = (d1 < d3s->d13 + m1);
717 		t2 = (d2 < d3s->d23 + m2);
718 		if (!t1 && !t2)
719 			break;
720 
721 		/* first file is different from others */
722 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
723 			/* stuff peculiar to 1st file */
724 			d1++;
725 			continue;
726 		}
727 
728 		/* second file is different from others */
729 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
730 			d2++;
731 			continue;
732 		}
733 
734 		/*
735 		 * Merge overlapping changes in first file
736 		 * this happens after extension (see below).
737 		 */
738 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
739 			d1[1].old.from = d1->old.from;
740 			d1[1].new.from = d1->new.from;
741 			d1++;
742 			continue;
743 		}
744 
745 		/* merge overlapping changes in second */
746 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
747 			d2[1].old.from = d2->old.from;
748 			d2[1].new.from = d2->new.from;
749 			d2++;
750 			continue;
751 		}
752 		/* stuff peculiar to third file or different in all */
753 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
754 			err = duplicate(&dpl, &d1->old, &d2->old, d3s);
755 			if (err)
756 				return err;
757 
758 			/*
759 			 * dpl = 0 means all files differ
760 			 * dpl = 1 means files 1 and 2 identical
761 			 */
762 			err = edit(d1, dpl, &j, d3s);
763 			if (err)
764 				return err;
765 			d1++;
766 			d2++;
767 			continue;
768 		}
769 
770 		/*
771 		 * Overlapping changes from file 1 and 2; extend changes
772 		 * appropriately to make them coincide.
773 		 */
774 		if (d1->new.from < d2->new.from) {
775 			d2->old.from -= d2->new.from - d1->new.from;
776 			d2->new.from = d1->new.from;
777 		} else if (d2->new.from < d1->new.from) {
778 			d1->old.from -= d1->new.from - d2->new.from;
779 			d1->new.from = d2->new.from;
780 		}
781 		if (d1->new.to > d2->new.to) {
782 			d2->old.to += d1->new.to - d2->new.to;
783 			d2->new.to = d1->new.to;
784 		} else if (d2->new.to > d1->new.to) {
785 			d1->old.to += d2->new.to - d1->new.to;
786 			d1->new.to = d2->new.to;
787 		}
788 	}
789 
790 	return (edscript(j, d3s));
791 }
792 
793 /*
794  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
795  */
796 static const struct got_error *
797 prange(struct range *rold, struct diff3_state *d3s)
798 {
799 	const struct got_error *err = NULL;
800 
801 	if (rold->to <= rold->from) {
802 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
803 		if (err)
804 			return err;
805 	} else {
806 		err = diff_output(d3s->diffbuf, "%d", rold->from);
807 		if (err)
808 			return err;
809 		if (rold->to > rold->from + 1) {
810 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
811 			if (err)
812 				return err;
813 		}
814 		err = diff_output(d3s->diffbuf, "c\n");
815 		if (err)
816 			return err;
817 	}
818 
819 	return NULL;
820 }
821 
822 /* skip to just before line number from in file "i". */
823 static const struct got_error *
824 skip(int *nskipped, int i, int from, struct diff3_state *d3s)
825 {
826 	const struct got_error *err = NULL;
827 	size_t len, n;
828 	char *line;
829 
830 	*nskipped = 0;
831 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
832 		err = get_line(&line, d3s->fp[i], &len, d3s);
833 		if (err)
834 			return err;
835 		d3s->cline[i]++;
836 	}
837 	*nskipped = n;
838 	return NULL;
839 }
840 
841 /*
842  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
843  * the same data as the new range (in file 2).
844  */
845 static const struct got_error *
846 duplicate(int *dpl, struct range *r1, struct range *r2, struct diff3_state *d3s)
847 {
848 	const struct got_error *err = NULL;
849 	int c,d;
850 	int nchar;
851 	int nline, nskipped;
852 
853 	*dpl = 0;
854 
855 	if (r1->to - r1->from != r2->to - r2->from)
856 		return NULL;
857 
858 	err = skip(&nskipped, 0, r1->from, d3s);
859 	if (err)
860 		return err;
861 	err = skip(&nskipped, 1, r2->from, d3s);
862 	if (err)
863 		return err;
864 	nchar = 0;
865 	for (nline = 0; nline < r1->to - r1->from; nline++) {
866 		do {
867 			c = getc(d3s->fp[0]);
868 			if (c == EOF)
869 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
870 			d = getc(d3s->fp[1]);
871 			if (d == EOF)
872 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
873 			nchar++;
874 			if (c != d)
875 				return repos(nchar, d3s);
876 		} while (c != '\n');
877 	}
878 	err = repos(nchar, d3s);
879 	if (err)
880 		return err;
881 	*dpl = 1;
882 	return NULL;
883 }
884 
885 static const struct got_error *
886 repos(int nchar, struct diff3_state *d3s)
887 {
888 	int i;
889 
890 	for (i = 0; i < 2; i++) {
891 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
892 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
893 	}
894 
895 	return NULL;
896 }
897 
898 /*
899  * collect an editing script for later regurgitation
900  */
901 static const struct got_error *
902 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
903 {
904 	const struct got_error *err = NULL;
905 	int nskipped;
906 
907 	if (((fdup + 1) & 3) == 0)
908 		return NULL;
909 	(*j)++;
910 	d3s->overlap[*j] = !fdup;
911 	if (!fdup)
912 		d3s->overlapcnt++;
913 	d3s->de[*j].old.from = diff->old.from;
914 	d3s->de[*j].old.to = diff->old.to;
915 	err = skip(&nskipped, 2, diff->new.from, d3s);
916 	if (err)
917 		return err;
918 	d3s->de[*j].new.from = d3s->de[*j - 1].new.to + nskipped;
919 	err = skip(&nskipped, 2, diff->new.to, d3s);
920 	d3s->de[*j].new.to = d3s->de[*j].new.from + nskipped;
921 	return NULL;
922 }
923 
924 /* regurgitate */
925 static const struct got_error *
926 edscript(int n, struct diff3_state *d3s)
927 {
928 	const struct got_error *err = NULL;
929 	int j, k;
930 	char block[BUFSIZ+1];
931 
932 	for (; n > 0; n--) {
933 		if (!d3s->overlap[n]) {
934 			err = prange(&d3s->de[n].old, d3s);
935 			if (err)
936 				return err;
937 		} else {
938 			err = diff_output(d3s->diffbuf, "%da\n%s\n",
939 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
940 			if (err)
941 				return err;
942 		}
943 		if (fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET)
944 		    == -1)
945 			return got_error_from_errno("fseek");
946 		k = d3s->de[n].new.to - d3s->de[n].new.from;
947 		for (; k > 0; k -= j) {
948 			j = k > BUFSIZ ? BUFSIZ : k;
949 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
950 				return got_ferror(d3s->fp[2], GOT_ERR_IO);
951 			block[j] = '\0';
952 			err = diff_output(d3s->diffbuf, "%s", block);
953 			if (err)
954 				return err;
955 		}
956 
957 		if (!d3s->overlap[n]) {
958 			err = diff_output(d3s->diffbuf, ".\n");
959 			if (err)
960 				return err;
961 		} else {
962 			err = diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
963 			if (err)
964 				return err;
965 			err = diff_output(d3s->diffbuf, "%da\n%s\n.\n",
966 			    d3s->de[n].old.from - 1, d3s->f1mark);
967 			if (err)
968 				return err;
969 		}
970 	}
971 
972 	return NULL;
973 }
974 
975 static const struct got_error *
976 increase(struct diff3_state *d3s)
977 {
978 	size_t newsz, incr;
979 	struct diff *d;
980 	char *s;
981 
982 	/* are the memset(3) calls needed? */
983 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
984 	incr = newsz - d3s->szchanges;
985 
986 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
987 	if (d == NULL)
988 		return got_error_from_errno("reallocarray");
989 	d3s->d13 = d;
990 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
991 
992 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
993 	if (d == NULL)
994 		return got_error_from_errno("reallocarray");
995 	d3s->d23 = d;
996 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
997 
998 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
999 	if (d == NULL)
1000 		return got_error_from_errno("reallocarray");
1001 	d3s->de = d;
1002 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1003 
1004 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1005 	if (s == NULL)
1006 		return got_error_from_errno("reallocarray");
1007 	d3s->overlap = s;
1008 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1009 	d3s->szchanges = newsz;
1010 
1011 	return NULL;
1012 }