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Date:: Wed Oct 9 07:26:28 2019 UTC
Message:: remove unused 'pr' argument from diff3.c's skip() function
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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 	(void)unlink(dp13);
389 	(void)unlink(dp23);
390 
391 	free(path1);
392 	free(path2);
393 	free(path3);
394 	free(dp13);
395 	free(dp23);
396 	free(data);
397 	free(patch);
398 
399 	worklist_clean(&temp_files, worklist_unlink);
400 
401 	for (i = 0; i < nitems(d3s->fp); i++) {
402 		if (d3s->fp[i] && fclose(d3s->fp[i]) != 0 && err == NULL)
403 			err = got_error_from_errno("fclose");
404 	}
405 	if (err == NULL && diffb) {
406 		if (buf_write_fd(diffb, outfd) < 0)
407 			err = got_error_from_errno("buf_write_fd");
408 		*overlapcnt = d3s->overlapcnt;
409 	}
410 	free(d3s);
411 	buf_free(diffb);
412 	return err;
413 }
414 
415 static const struct got_error *
416 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
417     const char *fmark, const char *rmark, struct diff3_state *d3s,
418     const char *label1, const char *label3)
419 {
420 	const struct got_error *err = NULL;
421 	ssize_t m, n;
422 	int i;
423 
424 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
425 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_BEGIN, label1);
426 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
427 		return got_error(GOT_ERR_NO_SPACE);
428 
429 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
430 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_END, label3);
431 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
432 		return got_error(GOT_ERR_NO_SPACE);
433 
434 	err = increase(d3s);
435 	if (err)
436 		return err;
437 
438 	err = readin(&m, dp13, &d3s->d13, d3s);
439 	if (err)
440 		return err;
441 	err = readin(&n, dp23, &d3s->d23, d3s);
442 	if (err)
443 		return err;
444 
445 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
446 		return got_error_from_errno2("fopen", path1);
447 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
448 		return got_error_from_errno2("fopen", path2);
449 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
450 		return got_error_from_errno2("fopen", path3);
451 
452 	return merge(m, n, d3s);
453 }
454 
455 static int
456 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
457 {
458 	char op, *ep;
459 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
460 	int start, end, i, lineno;
461 	u_char tmp;
462 
463 	dlp = TAILQ_FIRST(&(dlines->l_lines));
464 	lp = TAILQ_FIRST(&(plines->l_lines));
465 
466 	end = 0;
467 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
468 	    lp = TAILQ_NEXT(lp, l_list)) {
469 		/* Skip blank lines */
470 		if (lp->l_len < 2)
471 			continue;
472 
473 		/* NUL-terminate line buffer for strtol() safety. */
474 		tmp = lp->l_line[lp->l_len - 1];
475 		lp->l_line[lp->l_len - 1] = '\0';
476 
477 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
478 		op = lp->l_line[lp->l_len - 2];
479 		start = (int)strtol(lp->l_line, &ep, 10);
480 
481 		/* Restore the last byte of the buffer */
482 		lp->l_line[lp->l_len - 1] = tmp;
483 
484 		if (op == 'a') {
485 			if (start > dlines->l_nblines ||
486 			    start < 0 || *ep != 'a')
487 				return -1;
488 		} else if (op == 'c') {
489 			if (start > dlines->l_nblines ||
490 			    start < 0 || (*ep != ',' && *ep != 'c'))
491 				return -1;
492 
493 			if (*ep == ',') {
494 				ep++;
495 				end = (int)strtol(ep, &ep, 10);
496 				if (end < 0 || *ep != 'c')
497 					return -1;
498 			} else {
499 				end = start;
500 			}
501 		}
502 
503 
504 		for (;;) {
505 			if (dlp == NULL)
506 				break;
507 			if (dlp->l_lineno == start)
508 				break;
509 			if (dlp->l_lineno > start) {
510 				dlp = TAILQ_PREV(dlp, tqh, l_list);
511 			} else if (dlp->l_lineno < start) {
512 				ndlp = TAILQ_NEXT(dlp, l_list);
513 				if (ndlp->l_lineno > start)
514 					break;
515 				dlp = ndlp;
516 			}
517 		}
518 
519 		if (dlp == NULL)
520 			return -1;
521 
522 
523 		if (op == 'c') {
524 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
525 			for (i = 0; i <= (end - start); i++) {
526 				ndlp = TAILQ_NEXT(dlp, l_list);
527 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
528 				dlp = ndlp;
529 			}
530 			dlp = insert_after;
531 		}
532 
533 		if (op == 'a' || op == 'c') {
534 			for (;;) {
535 				ndlp = lp;
536 				lp = TAILQ_NEXT(lp, l_list);
537 				if (lp == NULL)
538 					return -1;
539 
540 				if (lp->l_len == 2 &&
541 				    lp->l_line[0] == '.' &&
542 				    lp->l_line[1] == '\n')
543 					break;
544 
545 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
546 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
547 				    lp, l_list);
548 				dlp = lp;
549 
550 				lp->l_lineno = start;
551 				lp = ndlp;
552 			}
553 		}
554 
555 		/*
556 		 * always resort lines as the markers might be put at the
557 		 * same line as we first started editing.
558 		 */
559 		lineno = 0;
560 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
561 			sort->l_lineno = lineno++;
562 		dlines->l_nblines = lineno - 1;
563 	}
564 
565 	return (0);
566 }
567 
568 /*
569  * Pick up the line numbers of all changes from one change file.
570  * (This puts the numbers in a vector, which is not strictly necessary,
571  * since the vector is processed in one sequential pass.
572  * The vector could be optimized out of existence)
573  */
574 static const struct got_error *
575 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
576 {
577 	const struct got_error *err = NULL;
578 	int a, b, c, d;
579 	char kind, *p;
580 	size_t i;
581 
582 	*n = 0;
583 
584 	d3s->fp[0] = fopen(name, "r");
585 	if (d3s->fp[0] == NULL)
586 		return got_error_from_errno2("fopen", name);
587 	err = getchange(&p, d3s->fp[0], d3s);
588 	if (err)
589 		return err;
590 	for (i = 0; p; i++) {
591 		if (i >= d3s->szchanges - 1) {
592 			err = increase(d3s);
593 			if (err)
594 				return err;
595 		}
596 		a = b = number(&p);
597 		if (*p == ',') {
598 			p++;
599 			b = number(&p);
600 		}
601 		kind = *p++;
602 		c = d = number(&p);
603 		if (*p == ',') {
604 			p++;
605 			d = number(&p);
606 		}
607 		if (kind == 'a')
608 			a++;
609 		if (kind == 'd')
610 			c++;
611 		b++;
612 		d++;
613 		(*dd)[i].old.from = a;
614 		(*dd)[i].old.to = b;
615 		(*dd)[i].new.from = c;
616 		(*dd)[i].new.to = d;
617 
618 		err = getchange(&p, d3s->fp[0], d3s);
619 		if (err)
620 			return err;
621 	}
622 
623 	if (i) {
624 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
625 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
626 	}
627 
628 	if (fclose(d3s->fp[0]) != 0)
629 		err = got_error_from_errno("fclose");
630 
631 	*n = i;
632 	return err;
633 }
634 
635 static int
636 number(char **lc)
637 {
638 	int nn;
639 
640 	nn = 0;
641 	while (isdigit((unsigned char)(**lc)))
642 		nn = nn*10 + *(*lc)++ - '0';
643 
644 	return (nn);
645 }
646 
647 static const struct got_error *
648 getchange(char **line, FILE *b, struct diff3_state *d3s)
649 {
650 	const struct got_error *err = NULL;
651 
652 	*line = NULL;
653 	do {
654 		if (*line && isdigit((unsigned char)(*line)[0]))
655 			return NULL;
656 		err = get_line(line, b, NULL, d3s);
657 		if (err)
658 			return err;
659 	} while (*line);
660 
661 	return NULL;
662 }
663 
664 static const struct got_error *
665 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
666 {
667 	const struct got_error *err = NULL;
668 	char *cp = NULL;
669 	size_t size;
670 	ssize_t len;
671 	char *new;
672 
673 	*ret = NULL;
674 
675 	len = getline(&cp, &size, b);
676 	if (len == -1) {
677 		if (ferror(b))
678 			err = got_error_from_errno("getline");
679 		goto done;
680 	}
681 
682 	if (cp[len - 1] != '\n') {
683 		len++;
684 		if (len + 1 > size) {
685 			new = realloc(cp, len + 1);
686 			if (new == NULL) {
687 				err = got_error_from_errno("realloc");
688 				goto done;
689 			}
690 			cp = new;
691 		}
692 		cp[len - 1] = '\n';
693 		cp[len] = '\0';
694 	}
695 
696 	free(d3s->buf);
697 	*ret = d3s->buf = cp;
698 	cp = NULL;
699 	if (n != NULL)
700 		*n = len;
701 done:
702 	free(cp);
703 	return err;
704 }
705 
706 static const struct got_error *
707 merge(size_t m1, size_t m2, struct diff3_state *d3s)
708 {
709 	const struct got_error *err = NULL;
710 	struct diff *d1, *d2;
711 	int dpl, j, t1, t2;
712 
713 	d1 = d3s->d13;
714 	d2 = d3s->d23;
715 	j = 0;
716 	for (;;) {
717 		t1 = (d1 < d3s->d13 + m1);
718 		t2 = (d2 < d3s->d23 + m2);
719 		if (!t1 && !t2)
720 			break;
721 
722 		/* first file is different from others */
723 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
724 			/* stuff peculiar to 1st file */
725 			d1++;
726 			continue;
727 		}
728 
729 		/* second file is different from others */
730 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
731 			d2++;
732 			continue;
733 		}
734 
735 		/*
736 		 * Merge overlapping changes in first file
737 		 * this happens after extension (see below).
738 		 */
739 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
740 			d1[1].old.from = d1->old.from;
741 			d1[1].new.from = d1->new.from;
742 			d1++;
743 			continue;
744 		}
745 
746 		/* merge overlapping changes in second */
747 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
748 			d2[1].old.from = d2->old.from;
749 			d2[1].new.from = d2->new.from;
750 			d2++;
751 			continue;
752 		}
753 		/* stuff peculiar to third file or different in all */
754 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
755 			err = duplicate(&dpl, &d1->old, &d2->old, d3s);
756 			if (err)
757 				return err;
758 
759 			/*
760 			 * dpl = 0 means all files differ
761 			 * dpl = 1 means files 1 and 2 identical
762 			 */
763 			err = edit(d1, dpl, &j, d3s);
764 			if (err)
765 				return err;
766 			d1++;
767 			d2++;
768 			continue;
769 		}
770 
771 		/*
772 		 * Overlapping changes from file 1 and 2; extend changes
773 		 * appropriately to make them coincide.
774 		 */
775 		if (d1->new.from < d2->new.from) {
776 			d2->old.from -= d2->new.from - d1->new.from;
777 			d2->new.from = d1->new.from;
778 		} else if (d2->new.from < d1->new.from) {
779 			d1->old.from -= d1->new.from - d2->new.from;
780 			d1->new.from = d2->new.from;
781 		}
782 		if (d1->new.to > d2->new.to) {
783 			d2->old.to += d1->new.to - d2->new.to;
784 			d2->new.to = d1->new.to;
785 		} else if (d2->new.to > d1->new.to) {
786 			d1->old.to += d2->new.to - d1->new.to;
787 			d1->new.to = d2->new.to;
788 		}
789 	}
790 
791 	return (edscript(j, d3s));
792 }
793 
794 /*
795  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
796  */
797 static const struct got_error *
798 prange(struct range *rold, struct diff3_state *d3s)
799 {
800 	const struct got_error *err = NULL;
801 
802 	if (rold->to <= rold->from) {
803 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
804 		if (err)
805 			return err;
806 	} else {
807 		err = diff_output(d3s->diffbuf, "%d", rold->from);
808 		if (err)
809 			return err;
810 		if (rold->to > rold->from + 1) {
811 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
812 			if (err)
813 				return err;
814 		}
815 		err = diff_output(d3s->diffbuf, "c\n");
816 		if (err)
817 			return err;
818 	}
819 
820 	return NULL;
821 }
822 
823 /* skip to just before line number from in file "i". */
824 static const struct got_error *
825 skip(int *nskipped, int i, int from, struct diff3_state *d3s)
826 {
827 	const struct got_error *err = NULL;
828 	size_t j, n;
829 	char *line;
830 
831 	*nskipped = 0;
832 	for (n = 0; d3s->cline[i] < from - 1; n += j) {
833 		err = get_line(&line, d3s->fp[i], &j, d3s);
834 		if (err)
835 			return err;
836 		d3s->cline[i]++;
837 	}
838 	*nskipped = n;
839 	return NULL;
840 }
841 
842 /*
843  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
844  * the same data as the new range (in file 2).
845  */
846 static const struct got_error *
847 duplicate(int *dpl, struct range *r1, struct range *r2, struct diff3_state *d3s)
848 {
849 	const struct got_error *err = NULL;
850 	int c,d;
851 	int nchar;
852 	int nline, nskipped;
853 
854 	*dpl = 0;
855 
856 	if (r1->to - r1->from != r2->to - r2->from)
857 		return NULL;
858 
859 	err = skip(&nskipped, 0, r1->from, d3s);
860 	if (err)
861 		return err;
862 	err = skip(&nskipped, 1, r2->from, d3s);
863 	if (err)
864 		return err;
865 	nchar = 0;
866 	for (nline = 0; nline < r1->to - r1->from; nline++) {
867 		do {
868 			c = getc(d3s->fp[0]);
869 			if (c == EOF)
870 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
871 			d = getc(d3s->fp[1]);
872 			if (d == EOF)
873 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
874 			nchar++;
875 			if (c != d)
876 				return repos(nchar, d3s);
877 		} while (c != '\n');
878 	}
879 	err = repos(nchar, d3s);
880 	if (err)
881 		return err;
882 	*dpl = 1;
883 	return NULL;
884 }
885 
886 static const struct got_error *
887 repos(int nchar, struct diff3_state *d3s)
888 {
889 	int i;
890 
891 	for (i = 0; i < 2; i++) {
892 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
893 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
894 	}
895 
896 	return NULL;
897 }
898 
899 /*
900  * collect an editing script for later regurgitation
901  */
902 static const struct got_error *
903 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
904 {
905 	const struct got_error *err = NULL;
906 	int nskipped;
907 
908 	if (((fdup + 1) & 3) == 0)
909 		return NULL;
910 	(*j)++;
911 	d3s->overlap[*j] = !fdup;
912 	if (!fdup)
913 		d3s->overlapcnt++;
914 	d3s->de[*j].old.from = diff->old.from;
915 	d3s->de[*j].old.to = diff->old.to;
916 	err = skip(&nskipped, 2, diff->new.from, d3s);
917 	if (err)
918 		return err;
919 	d3s->de[*j].new.from = d3s->de[*j - 1].new.to + nskipped;
920 	err = skip(&nskipped, 2, diff->new.to, d3s);
921 	d3s->de[*j].new.to = d3s->de[*j].new.from + nskipped;
922 	return NULL;
923 }
924 
925 /* regurgitate */
926 static const struct got_error *
927 edscript(int n, struct diff3_state *d3s)
928 {
929 	const struct got_error *err = NULL;
930 	int j, k;
931 	char block[BUFSIZ+1];
932 
933 	for (; n > 0; n--) {
934 		if (!d3s->overlap[n]) {
935 			err = prange(&d3s->de[n].old, d3s);
936 			if (err)
937 				return err;
938 		} else {
939 			err = diff_output(d3s->diffbuf, "%da\n%s\n",
940 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
941 			if (err)
942 				return err;
943 		}
944 		if (fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET)
945 		    == -1)
946 			return got_error_from_errno("fseek");
947 		k = d3s->de[n].new.to - d3s->de[n].new.from;
948 		for (; k > 0; k -= j) {
949 			j = k > BUFSIZ ? BUFSIZ : k;
950 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
951 				return got_ferror(d3s->fp[2], GOT_ERR_IO);
952 			block[j] = '\0';
953 			err = diff_output(d3s->diffbuf, "%s", block);
954 			if (err)
955 				return err;
956 		}
957 
958 		if (!d3s->overlap[n]) {
959 			err = diff_output(d3s->diffbuf, ".\n");
960 			if (err)
961 				return err;
962 		} else {
963 			err = diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
964 			if (err)
965 				return err;
966 			err = diff_output(d3s->diffbuf, "%da\n%s\n.\n",
967 			    d3s->de[n].old.from - 1, d3s->f1mark);
968 			if (err)
969 				return err;
970 		}
971 	}
972 
973 	return NULL;
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 }