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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 
69 #include <ctype.h>
70 #include <limits.h>
71 #include <stdio.h>
72 #include <stdarg.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <time.h>
76 #include <unistd.h>
77 
78 #include "got_error.h"
79 #include "got_opentemp.h"
80 #include "got_object.h"
81 
82 #include "buf.h"
83 #include "rcsutil.h"
84 #include "got_lib_diff.h"
85 
86 #ifndef nitems
87 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
88 #endif
89 
90 /* diff3 - 3-way differential file comparison */
91 
92 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
93  *
94  * d13 = diff report on f1 vs f3
95  * d23 = diff report on f2 vs f3
96  * f1, f2, f3 the 3 files
97  * if changes in f1 overlap with changes in f3, m1 and m3 are used
98  * to mark the overlaps; otherwise, the file names f1 and f3 are used
99  * (only for options E and X).
100  */
101 
102 /*
103  * "from" is first in range of changed lines; "to" is last+1
104  * from=to=line after point of insertion for added lines.
105  */
106 struct line_range {
107 	int from;
108 	int to;
109 };
110 
111 struct off_range {
112 	off_t from;
113 	off_t to;
114 };
115 
116 struct diff {
117 	struct line_range old;
118 	struct line_range new;
119 	struct off_range oldo;
120 	struct off_range newo;
121 };
122 
123 struct diff3_state {
124 	size_t szchanges;
125 
126 	struct diff *d13;
127 	struct diff *d23;
128 
129 	/*
130 	 * "de" is used to gather editing scripts.  These are later spewed out
131 	 * in reverse order.  Its first element must be all zero, the "new"
132 	 * component of "de" contains line positions, and "oldo" and "newo"
133 	 * components contain byte positions.
134 	 * Array overlap indicates which sections in "de" correspond to lines
135 	 * that are different in all three files.
136 	 */
137 	struct diff *de;
138 	char *overlap;
139 	int overlapcnt;
140 	FILE *fp[3];
141 	int cline[3];		/* # of the last-read line in each file (0-2) */
142 
143 	/*
144 	 * the latest known correspondence between line numbers of the 3 files
145 	 * is stored in last[1-3];
146 	 */
147 	int last[4];
148 	char f1mark[PATH_MAX];
149 	char f2mark[PATH_MAX];
150 	char f3mark[PATH_MAX];
151 
152 	char *buf;
153 
154 	BUF *diffbuf;
155 };
156 
157 
158 static const struct got_error *duplicate(int *, int, struct line_range *,
159     struct line_range *, struct diff3_state *);
160 static const struct got_error *edit(struct diff *, int, int *,
161     struct diff3_state *);
162 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
163 static const struct got_error *get_line(char **, FILE *, size_t *,
164     struct diff3_state *);
165 static int number(char **);
166 static const struct got_error *readin(size_t *, char *, struct diff **,
167     struct diff3_state *);
168 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
169 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
170 static const struct got_error *edscript(int, struct diff3_state *);
171 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
172 static const struct got_error *prange(struct line_range *,
173     struct diff3_state *);
174 static const struct got_error *repos(int, struct diff3_state *);
175 static const struct got_error *increase(struct diff3_state *);
176 static const struct got_error *diff3_internal(char *, char *, char *,
177     char *, char *, const char *, const char *, struct diff3_state *,
178     const char *, const char *, const char *);
179 
180 static const struct got_error *
181 diff_output(BUF *diffbuf, const char *fmt, ...)
182 {
183 	const struct got_error *err = NULL;
184 	va_list vap;
185 	int i;
186 	char *str;
187 	size_t newsize;
188 
189 	va_start(vap, fmt);
190 	i = vasprintf(&str, fmt, vap);
191 	va_end(vap);
192 	if (i == -1)
193 		return got_error_from_errno("vasprintf");
194 	err = buf_append(&newsize, diffbuf, str, strlen(str));
195 	free(str);
196 	return err;
197 }
198 
199 static const struct got_error*
200 diffreg(BUF **d, const char *path1, const char *path2,
201     enum got_diff_algorithm diff_algo)
202 {
203 	const struct got_error *err = NULL;
204 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
205 	char *outpath = NULL;
206 	struct got_diffreg_result *diffreg_result = NULL;
207 
208 	*d = NULL;
209 
210 	f1 = fopen(path1, "re");
211 	if (f1 == NULL) {
212 		err = got_error_from_errno2("fopen", path1);
213 		goto done;
214 	}
215 	f2 = fopen(path2, "re");
216 	if (f1 == NULL) {
217 		err = got_error_from_errno2("fopen", path2);
218 		goto done;
219 	}
220 
221 	err = got_opentemp_named(&outpath, &outfile,
222 	    GOT_TMPDIR_STR "/got-diffreg");
223 	if (err)
224 		goto done;
225 
226 	err = got_diffreg(&diffreg_result, f1, f2, diff_algo, 0, 0);
227 	if (err)
228 		goto done;
229 
230 	if (diffreg_result) {
231 		struct diff_result *diff_result = diffreg_result->result;
232 		int atomizer_flags = (diff_result->left->atomizer_flags |
233 		    diff_result->right->atomizer_flags);
234 		if ((atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA)) {
235 			err = got_error(GOT_ERR_FILE_BINARY);
236 			goto done;
237 		}
238 	}
239 
240 	err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
241 	    GOT_DIFF_OUTPUT_EDSCRIPT, 0, outfile);
242 	if (err)
243 		goto done;
244 
245 	if (fflush(outfile) != 0) {
246 		err = got_error_from_errno2("fflush", outpath);
247 		goto done;
248 	}
249 	if (fseek(outfile, 0L, SEEK_SET) == -1) {
250 		err = got_ferror(outfile, GOT_ERR_IO);
251 		goto done;
252 	}
253 
254 	err = buf_load(d, outfile);
255 done:
256 	if (outpath) {
257 		if (unlink(outpath) == -1 && err == NULL)
258 			err = got_error_from_errno2("unlink", outpath);
259 		free(outpath);
260 	}
261 	if (outfile && fclose(outfile) == EOF && err == NULL)
262 		err = got_error_from_errno("fclose");
263 	if (f1 && fclose(f1) == EOF && err == NULL)
264 		err = got_error_from_errno("fclose");
265 	if (f2 && fclose(f2) == EOF && err == NULL)
266 		err = got_error_from_errno("fclose");
267 	return err;
268 }
269 
270 /*
271  * For merge(1).
272  */
273 const struct got_error *
274 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
275     FILE *f3, const char *label1, const char *label2, const char *label3,
276     enum got_diff_algorithm diff_algo)
277 {
278 	const struct got_error *err = NULL;
279 	char *dp13, *dp23, *path1, *path2, *path3;
280 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
281 	u_char *data, *patch;
282 	size_t dlen, plen, i;
283 	struct diff3_state *d3s;
284 
285 	*overlapcnt = 0;
286 
287 	d3s = calloc(1, sizeof(*d3s));
288 	if (d3s == NULL)
289 		return got_error_from_errno("calloc");
290 
291 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
292 	dp13 = dp23 = path1 = path2 = path3 = NULL;
293 	data = patch = NULL;
294 
295 	err = buf_load(&b1, f1);
296 	if (err)
297 		goto out;
298 	err = buf_load(&b2, f2);
299 	if (err)
300 		goto out;
301 	err = buf_load(&b3, f3);
302 	if (err)
303 		goto out;
304 
305 	err = buf_alloc(&diffb, 128);
306 	if (err)
307 		goto out;
308 
309 	if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXX") == -1) {
310 		err = got_error_from_errno("asprintf");
311 		goto out;
312 	}
313 	if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXX") == -1) {
314 		err = got_error_from_errno("asprintf");
315 		goto out;
316 	}
317 	if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXX") == -1) {
318 		err = got_error_from_errno("asprintf");
319 		goto out;
320 	}
321 
322 	err = buf_write_stmp(b1, path1);
323 	if (err)
324 		goto out;
325 	err = buf_write_stmp(b2, path2);
326 	if (err)
327 		goto out;
328 	err = buf_write_stmp(b3, path3);
329 	if (err)
330 		goto out;
331 
332 	buf_free(b2);
333 	b2 = NULL;
334 
335 	err = diffreg(&d1, path1, path3, diff_algo);
336 	if (err) {
337 		buf_free(diffb);
338 		diffb = NULL;
339 		goto out;
340 
341 	}
342 	err = diffreg(&d2, path2, path3, diff_algo);
343 	if (err) {
344 		buf_free(diffb);
345 		diffb = NULL;
346 		goto out;
347 	}
348 
349 	if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
350 		err = got_error_from_errno("asprintf");
351 		goto out;
352 	}
353 	err = buf_write_stmp(d1, dp13);
354 	if (err)
355 		goto out;
356 
357 	buf_free(d1);
358 	d1 = NULL;
359 
360 	if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
361 		err = got_error_from_errno("asprintf");
362 		goto out;
363 	}
364 	err = buf_write_stmp(d2, dp23);
365 	if (err)
366 		goto out;
367 
368 	buf_free(d2);
369 	d2 = NULL;
370 
371 	d3s->diffbuf = diffb;
372 	err = diff3_internal(dp13, dp23, path1, path2, path3,
373 	    label1, label3, d3s, label1, label2, label3);
374 	if (err) {
375 		buf_free(diffb);
376 		diffb = NULL;
377 		goto out;
378 	}
379 
380 	plen = buf_len(diffb);
381 	patch = buf_release(diffb);
382 	dlen = buf_len(b1);
383 	data = buf_release(b1);
384 
385 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
386 out:
387 	buf_free(b2);
388 	buf_free(b3);
389 	buf_free(d1);
390 	buf_free(d2);
391 
392 	if (unlink(path1) == -1 && err == NULL)
393 		err = got_error_from_errno2("unlink", path1);
394 	if (unlink(path2) == -1 && err == NULL)
395 		err = got_error_from_errno2("unlink", path2);
396 	if (unlink(path3) == -1 && err == NULL)
397 		err = got_error_from_errno2("unlink", path3);
398 	if (unlink(dp13) == -1 && err == NULL)
399 		err = got_error_from_errno2("unlink", dp13);
400 	if (unlink(dp23) == -1 && err == NULL)
401 		err = got_error_from_errno2("unlink", dp23);
402 
403 	free(path1);
404 	free(path2);
405 	free(path3);
406 	free(dp13);
407 	free(dp23);
408 	free(data);
409 	free(patch);
410 
411 	for (i = 0; i < nitems(d3s->fp); i++) {
412 		if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
413 			err = got_error_from_errno("fclose");
414 	}
415 	if (err == NULL && diffb) {
416 		if (buf_write_fd(diffb, outfd) < 0)
417 			err = got_error_from_errno("buf_write_fd");
418 		*overlapcnt = d3s->overlapcnt;
419 	}
420 	free(d3s);
421 	buf_free(diffb);
422 	return err;
423 }
424 
425 static const struct got_error *
426 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
427     const char *fmark, const char *rmark, struct diff3_state *d3s,
428     const char *label1, const char *label2, const char *label3)
429 {
430 	const struct got_error *err = NULL;
431 	ssize_t m, n;
432 	int i;
433 
434 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
435 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
436 	    label1 ? " " : "", label1 ? label1 : "");
437 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
438 		return got_error(GOT_ERR_NO_SPACE);
439 
440 	i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
441 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
442 	    label2 ? " " : "", label2 ? label2 : "");
443 	if (i < 0 || i >= (int)sizeof(d3s->f2mark))
444 		return got_error(GOT_ERR_NO_SPACE);
445 
446 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
447 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
448 	    label3 ? " " : "", label3 ? label3 : "");
449 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
450 		return got_error(GOT_ERR_NO_SPACE);
451 
452 	err = increase(d3s);
453 	if (err)
454 		return err;
455 
456 	err = readin(&m, dp13, &d3s->d13, d3s);
457 	if (err)
458 		return err;
459 	err = readin(&n, dp23, &d3s->d23, d3s);
460 	if (err)
461 		return err;
462 
463 	if ((d3s->fp[0] = fopen(path1, "re")) == NULL)
464 		return got_error_from_errno2("fopen", path1);
465 	if ((d3s->fp[1] = fopen(path2, "re")) == NULL)
466 		return got_error_from_errno2("fopen", path2);
467 	if ((d3s->fp[2] = fopen(path3, "re")) == NULL)
468 		return got_error_from_errno2("fopen", path3);
469 
470 	return merge(m, n, d3s);
471 }
472 
473 static int
474 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
475 {
476 	char op, *ep;
477 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
478 	int start, end, i, lineno;
479 	u_char tmp;
480 
481 	dlp = TAILQ_FIRST(&(dlines->l_lines));
482 	lp = TAILQ_FIRST(&(plines->l_lines));
483 
484 	end = 0;
485 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
486 	    lp = TAILQ_NEXT(lp, l_list)) {
487 		/* Skip blank lines */
488 		if (lp->l_len < 2)
489 			continue;
490 
491 		/* NUL-terminate line buffer for strtol() safety. */
492 		tmp = lp->l_line[lp->l_len - 1];
493 		lp->l_line[lp->l_len - 1] = '\0';
494 
495 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
496 		op = lp->l_line[lp->l_len - 2];
497 		start = (int)strtol(lp->l_line, &ep, 10);
498 
499 		/* Restore the last byte of the buffer */
500 		lp->l_line[lp->l_len - 1] = tmp;
501 
502 		if (op == 'a') {
503 			if (start > dlines->l_nblines ||
504 			    start < 0 || *ep != 'a')
505 				return -1;
506 		} else if (op == 'c') {
507 			if (start > dlines->l_nblines ||
508 			    start < 0 || (*ep != ',' && *ep != 'c'))
509 				return -1;
510 
511 			if (*ep == ',') {
512 				ep++;
513 				end = (int)strtol(ep, &ep, 10);
514 				if (end < 0 || *ep != 'c')
515 					return -1;
516 			} else {
517 				end = start;
518 			}
519 		}
520 
521 
522 		for (;;) {
523 			if (dlp == NULL)
524 				break;
525 			if (dlp->l_lineno == start)
526 				break;
527 			if (dlp->l_lineno > start) {
528 				dlp = TAILQ_PREV(dlp, tqh, l_list);
529 			} else if (dlp->l_lineno < start) {
530 				ndlp = TAILQ_NEXT(dlp, l_list);
531 				if (ndlp->l_lineno > start)
532 					break;
533 				dlp = ndlp;
534 			}
535 		}
536 
537 		if (dlp == NULL)
538 			return -1;
539 
540 
541 		if (op == 'c') {
542 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
543 			for (i = 0; i <= (end - start); i++) {
544 				ndlp = TAILQ_NEXT(dlp, l_list);
545 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
546 				dlp = ndlp;
547 			}
548 			dlp = insert_after;
549 		}
550 
551 		if (op == 'a' || op == 'c') {
552 			for (;;) {
553 				ndlp = lp;
554 				lp = TAILQ_NEXT(lp, l_list);
555 				if (lp == NULL)
556 					return -1;
557 
558 				if (lp->l_len == 2 &&
559 				    lp->l_line[0] == '.' &&
560 				    lp->l_line[1] == '\n')
561 					break;
562 
563 				if (lp->l_line[0] == ':') {
564 					lp->l_line++;
565 					lp->l_len--;
566 				}
567 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
568 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
569 				    lp, l_list);
570 				dlp = lp;
571 
572 				lp->l_lineno = start;
573 				lp = ndlp;
574 			}
575 		}
576 
577 		/*
578 		 * always resort lines as the markers might be put at the
579 		 * same line as we first started editing.
580 		 */
581 		lineno = 0;
582 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
583 			sort->l_lineno = lineno++;
584 		dlines->l_nblines = lineno - 1;
585 	}
586 
587 	return (0);
588 }
589 
590 /*
591  * Pick up the line numbers of all changes from one change file.
592  * (This puts the numbers in a vector, which is not strictly necessary,
593  * since the vector is processed in one sequential pass.
594  * The vector could be optimized out of existence)
595  */
596 static const struct got_error *
597 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
598 {
599 	const struct got_error *err = NULL;
600 	FILE *f;
601 	int a, b, c, d;
602 	char kind, *p;
603 	size_t i = 0;
604 
605 	*n = 0;
606 
607 	f = fopen(name, "re");
608 	if (f == NULL)
609 		return got_error_from_errno2("fopen", name);
610 	err = getchange(&p, f, d3s);
611 	if (err)
612 		goto done;
613 	for (i = 0; p; i++) {
614 		if (i >= d3s->szchanges - 1) {
615 			err = increase(d3s);
616 			if (err)
617 				goto done;
618 		}
619 		a = b = number(&p);
620 		if (*p == ',') {
621 			p++;
622 			b = number(&p);
623 		}
624 		kind = *p++;
625 		c = d = number(&p);
626 		if (*p == ',') {
627 			p++;
628 			d = number(&p);
629 		}
630 		if (kind == 'a')
631 			a++;
632 		if (kind == 'd')
633 			c++;
634 		b++;
635 		d++;
636 		(*dd)[i].old.from = a;
637 		(*dd)[i].old.to = b;
638 		(*dd)[i].new.from = c;
639 		(*dd)[i].new.to = d;
640 
641 		err = getchange(&p, f, d3s);
642 		if (err)
643 			goto done;
644 	}
645 
646 	if (i) {
647 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
648 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
649 	}
650 done:
651 	if (fclose(f) == EOF && err == NULL)
652 		err = got_error_from_errno("fclose");
653 	if (err == NULL)
654 		*n = i;
655 	return err;
656 }
657 
658 static int
659 number(char **lc)
660 {
661 	int nn;
662 
663 	nn = 0;
664 	while (isdigit((unsigned char)(**lc)))
665 		nn = nn*10 + *(*lc)++ - '0';
666 
667 	return (nn);
668 }
669 
670 static const struct got_error *
671 getchange(char **line, FILE *b, struct diff3_state *d3s)
672 {
673 	const struct got_error *err = NULL;
674 
675 	*line = NULL;
676 	do {
677 		if (*line && isdigit((unsigned char)(*line)[0]))
678 			return NULL;
679 		err = get_line(line, b, NULL, d3s);
680 		if (err)
681 			return err;
682 	} while (*line);
683 
684 	return NULL;
685 }
686 
687 static const struct got_error *
688 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
689 {
690 	const struct got_error *err = NULL;
691 	char *cp = NULL;
692 	size_t size;
693 	ssize_t len;
694 	char *new;
695 
696 	*ret = NULL;
697 	if (n != NULL)
698 		*n = 0;
699 
700 	len = getline(&cp, &size, b);
701 	if (len == -1) {
702 		if (ferror(b))
703 			err = got_error_from_errno("getline");
704 		goto done;
705 	}
706 
707 	if (cp[len - 1] != '\n') {
708 		len++;
709 		if (len + 1 > size) {
710 			new = realloc(cp, len + 1);
711 			if (new == NULL) {
712 				err = got_error_from_errno("realloc");
713 				goto done;
714 			}
715 			cp = new;
716 		}
717 		cp[len - 1] = '\n';
718 		cp[len] = '\0';
719 	}
720 
721 	free(d3s->buf);
722 	*ret = d3s->buf = cp;
723 	cp = NULL;
724 	if (n != NULL)
725 		*n = len;
726 done:
727 	free(cp);
728 	return err;
729 }
730 
731 static const struct got_error *
732 merge(size_t m1, size_t m2, struct diff3_state *d3s)
733 {
734 	const struct got_error *err = NULL;
735 	struct diff *d1, *d2;
736 	int dpl, j, t1, t2;
737 
738 	d1 = d3s->d13;
739 	d2 = d3s->d23;
740 	j = 0;
741 	for (;;) {
742 		t1 = (d1 < d3s->d13 + m1);
743 		t2 = (d2 < d3s->d23 + m2);
744 		if (!t1 && !t2)
745 			break;
746 
747 		/* first file is different from others */
748 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
749 			/* stuff peculiar to 1st file */
750 			d1++;
751 			continue;
752 		}
753 
754 		/* second file is different from others */
755 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
756 			d2++;
757 			continue;
758 		}
759 
760 		/*
761 		 * Merge overlapping changes in first file
762 		 * this happens after extension (see below).
763 		 */
764 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
765 			d1[1].old.from = d1->old.from;
766 			d1[1].new.from = d1->new.from;
767 			d1++;
768 			continue;
769 		}
770 
771 		/* merge overlapping changes in second */
772 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
773 			d2[1].old.from = d2->old.from;
774 			d2[1].new.from = d2->new.from;
775 			d2++;
776 			continue;
777 		}
778 		/* stuff peculiar to third file or different in all */
779 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
780 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
781 			if (err)
782 				return err;
783 
784 			/*
785 			 * dpl = 0 means all files differ
786 			 * dpl = 1 means files 1 and 2 identical
787 			 */
788 			err = edit(d1, dpl, &j, d3s);
789 			if (err)
790 				return err;
791 			d1++;
792 			d2++;
793 			continue;
794 		}
795 
796 		/*
797 		 * Overlapping changes from file 1 and 2; extend changes
798 		 * appropriately to make them coincide.
799 		 */
800 		if (d1->new.from < d2->new.from) {
801 			d2->old.from -= d2->new.from - d1->new.from;
802 			d2->new.from = d1->new.from;
803 		} else if (d2->new.from < d1->new.from) {
804 			d1->old.from -= d1->new.from - d2->new.from;
805 			d1->new.from = d2->new.from;
806 		}
807 		if (d1->new.to > d2->new.to) {
808 			d2->old.to += d1->new.to - d2->new.to;
809 			d2->new.to = d1->new.to;
810 		} else if (d2->new.to > d1->new.to) {
811 			d1->old.to += d2->new.to - d1->new.to;
812 			d1->new.to = d2->new.to;
813 		}
814 	}
815 
816 	return (edscript(j, d3s));
817 }
818 
819 /*
820  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
821  */
822 static const struct got_error *
823 prange(struct line_range *rold, struct diff3_state *d3s)
824 {
825 	const struct got_error *err = NULL;
826 
827 	if (rold->to <= rold->from) {
828 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
829 		if (err)
830 			return err;
831 	} else {
832 		err = diff_output(d3s->diffbuf, "%d", rold->from);
833 		if (err)
834 			return err;
835 		if (rold->to > rold->from + 1) {
836 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
837 			if (err)
838 				return err;
839 		}
840 		err = diff_output(d3s->diffbuf, "c\n");
841 		if (err)
842 			return err;
843 	}
844 
845 	return NULL;
846 }
847 
848 /*
849  * Skip to just before line number from in file "i".
850  * Return the number of bytes skipped in *nskipped.
851  */
852 static const struct got_error *
853 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
854 {
855 	const struct got_error *err = NULL;
856 	size_t len, n;
857 	char *line;
858 
859 	*nskipped = 0;
860 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
861 		err = get_line(&line, d3s->fp[i], &len, d3s);
862 		if (err)
863 			return err;
864 		d3s->cline[i]++;
865 	}
866 	*nskipped = n;
867 	return NULL;
868 }
869 
870 /*
871  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
872  * the same data as the new range (in file 2).
873  *
874  * If this change could overlap, remember start/end offsets in file 2 so we
875  * can write out the original lines of text if a merge conflict occurs.
876  */
877 static const struct got_error *
878 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
879     struct diff3_state *d3s)
880 {
881 	const struct got_error *err = NULL;
882 	int c,d;
883 	int nchar;
884 	int nline;
885 	size_t nskipped;
886 	off_t off;
887 
888 	*dpl = 0;
889 
890 	if (r1->to - r1->from != r2->to - r2->from)
891 		return NULL;
892 
893 	err = skip(&nskipped, 0, r1->from, d3s);
894 	if (err)
895 		return err;
896 	err = skip(&nskipped, 1, r2->from, d3s);
897 	if (err)
898 		return err;
899 
900 	off = ftello(d3s->fp[1]);
901 	if (off == -1)
902 		return got_error_from_errno("ftello");
903 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
904 
905 	nchar = 0;
906 	for (nline = 0; nline < r1->to - r1->from; nline++) {
907 		do {
908 			c = getc(d3s->fp[0]);
909 			d = getc(d3s->fp[1]);
910 			if (c == EOF && d == EOF)
911 				break;
912 			else if (c == EOF)
913 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
914 			else if (d == EOF)
915 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
916 			nchar++;
917 			if (c != d) {
918 				long orig_line_len = nchar;
919 				while (d != '\n') {
920 					d = getc(d3s->fp[1]);
921 					if (d == EOF)
922 						break;
923 					orig_line_len++;
924 				}
925 				if (orig_line_len > nchar &&
926 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
927 				    SEEK_CUR) == -1)
928 					return got_ferror(d3s->fp[1],
929 						GOT_ERR_IO);
930 				/* original lines end here */
931 				d3s->de[j + 1].oldo.to = off + orig_line_len;
932 				err = repos(nchar, d3s);
933 				if (err)
934 					return err;
935 				return NULL;
936 			}
937 		} while (c != '\n');
938 	}
939 
940 	/* original lines end here */
941 	d3s->de[j + 1].oldo.to = off + nchar;
942 
943 	err = repos(nchar, d3s);
944 	if (err)
945 		return err;
946 	*dpl = 1;
947 	return NULL;
948 }
949 
950 static const struct got_error *
951 repos(int nchar, struct diff3_state *d3s)
952 {
953 	int i;
954 
955 	for (i = 0; i < 2; i++) {
956 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
957 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
958 	}
959 
960 	return NULL;
961 }
962 
963 /*
964  * collect an editing script for later regurgitation
965  */
966 static const struct got_error *
967 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
968 {
969 	const struct got_error *err = NULL;
970 	size_t nskipped;
971 
972 	if (((fdup + 1) & 3) == 0)
973 		return NULL;
974 	(*j)++;
975 	d3s->overlap[*j] = !fdup;
976 	if (!fdup)
977 		d3s->overlapcnt++;
978 	d3s->de[*j].old.from = diff->old.from;
979 	d3s->de[*j].old.to = diff->old.to;
980 
981 	err = skip(&nskipped, 2, diff->new.from, d3s);
982 	if (err)
983 		return err;
984 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
985 
986 	err = skip(&nskipped, 2, diff->new.to, d3s);
987 	if (err)
988 		return err;
989 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
990 	return NULL;
991 }
992 
993 /* regurgitate */
994 static const struct got_error *
995 edscript(int n, struct diff3_state *d3s)
996 {
997 	const struct got_error *err = NULL;
998 	off_t len;
999 	char *line = NULL;
1000 	size_t linesize = 0;
1001 	ssize_t linelen = 0, k;
1002 
1003 	for (; n > 0; n--) {
1004 		if (!d3s->overlap[n]) {
1005 			err = prange(&d3s->de[n].old, d3s);
1006 			if (err)
1007 				return err;
1008 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
1009 			/* Output a block of 3-way diff base file content. */
1010 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1011 			    d3s->de[n].old.to - 1, d3s->f2mark);
1012 			if (err)
1013 				return err;
1014 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1015 			    == -1)
1016 				return got_error_from_errno("fseeko");
1017 			len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1018 			for (k = 0; k < (ssize_t)len; k += linelen) {
1019 				linelen = getline(&line, &linesize, d3s->fp[1]);
1020 				if (linelen == -1) {
1021 					if (feof(d3s->fp[1]))
1022 						break;
1023 					err = got_ferror(d3s->fp[1],
1024 					    GOT_ERR_IO);
1025 					goto done;
1026 				}
1027 				err = diff_output(d3s->diffbuf, ":%s", line);
1028 				if (err)
1029 					goto done;
1030 			}
1031 			err = diff_output(d3s->diffbuf, "%s%s\n",
1032 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1033 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1034 			if (err)
1035 				goto done;
1036 		} else {
1037 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1038 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1039 			if (err)
1040 				goto done;
1041 		}
1042 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1043 		    == -1) {
1044 			err = got_error_from_errno("fseek");
1045 			goto done;
1046 		}
1047 		len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1048 		for (k = 0; k < (ssize_t)len; k += linelen) {
1049 			linelen = getline(&line, &linesize, d3s->fp[2]);
1050 			if (linelen == -1) {
1051 				if (feof(d3s->fp[2]))
1052 					break;
1053 				err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1054 				goto done;
1055 			}
1056 			err = diff_output(d3s->diffbuf, ":%s", line);
1057 			if (err)
1058 				goto done;
1059 		}
1060 
1061 		if (!d3s->overlap[n]) {
1062 			err = diff_output(d3s->diffbuf, ".\n");
1063 			if (err)
1064 				goto done;
1065 		} else {
1066 			err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1067 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1068 			    d3s->f3mark);
1069 			if (err)
1070 				goto done;
1071 			err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1072 			    d3s->de[n].old.from - 1, d3s->f1mark);
1073 			if (err)
1074 				goto done;
1075 		}
1076 	}
1077 done:
1078 	free(line);
1079 	return err;
1080 }
1081 
1082 static const struct got_error *
1083 increase(struct diff3_state *d3s)
1084 {
1085 	size_t newsz, incr;
1086 	struct diff *d;
1087 	char *s;
1088 
1089 	/* are the memset(3) calls needed? */
1090 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1091 	incr = newsz - d3s->szchanges;
1092 
1093 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1094 	if (d == NULL)
1095 		return got_error_from_errno("reallocarray");
1096 	d3s->d13 = d;
1097 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1098 
1099 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1100 	if (d == NULL)
1101 		return got_error_from_errno("reallocarray");
1102 	d3s->d23 = d;
1103 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1104 
1105 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1106 	if (d == NULL)
1107 		return got_error_from_errno("reallocarray");
1108 	d3s->de = d;
1109 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1110 
1111 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1112 	if (s == NULL)
1113 		return got_error_from_errno("reallocarray");
1114 	d3s->overlap = s;
1115 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1116 	d3s->szchanges = newsz;
1117 
1118 	return NULL;
1119 }