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 
87 #ifndef nitems
88 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
89 #endif
90 
91 /* diff3 - 3-way differential file comparison */
92 
93 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
94  *
95  * d13 = diff report on f1 vs f3
96  * d23 = diff report on f2 vs f3
97  * f1, f2, f3 the 3 files
98  * if changes in f1 overlap with changes in f3, m1 and m3 are used
99  * to mark the overlaps; otherwise, the file names f1 and f3 are used
100  * (only for options E and X).
101  */
102 
103 /*
104  * "from" is first in range of changed lines; "to" is last+1
105  * from=to=line after point of insertion for added lines.
106  */
107 struct line_range {
108 	int from;
109 	int to;
110 };
111 
112 struct off_range {
113 	off_t from;
114 	off_t to;
115 };
116 
117 struct diff {
118 	struct line_range old;
119 	struct line_range new;
120 	struct off_range oldo;
121 	struct off_range newo;
122 };
123 
124 struct diff3_state {
125 	size_t szchanges;
126 
127 	struct diff *d13;
128 	struct diff *d23;
129 
130 	/*
131 	 * "de" is used to gather editing scripts.  These are later spewed out
132 	 * in reverse order.  Its first element must be all zero, the "new"
133 	 * component of "de" contains line positions, and "oldo" and "newo"
134 	 * components contain byte positions.
135 	 * Array overlap indicates which sections in "de" correspond to lines
136 	 * that are different in all three files.
137 	 */
138 	struct diff *de;
139 	char *overlap;
140 	int overlapcnt;
141 	FILE *fp[3];
142 	int cline[3];		/* # of the last-read line in each file (0-2) */
143 
144 	/*
145 	 * the latest known correspondence between line numbers of the 3 files
146 	 * is stored in last[1-3];
147 	 */
148 	int last[4];
149 	char f1mark[PATH_MAX];
150 	char f2mark[PATH_MAX];
151 	char f3mark[PATH_MAX];
152 
153 	char *buf;
154 
155 	BUF *diffbuf;
156 };
157 
158 
159 static const struct got_error *duplicate(int *, int, struct line_range *,
160     struct line_range *, struct diff3_state *);
161 static const struct got_error *edit(struct diff *, int, int *,
162     struct diff3_state *);
163 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
164 static const struct got_error *get_line(char **, FILE *, size_t *,
165     struct diff3_state *);
166 static int number(char **);
167 static const struct got_error *readin(size_t *, char *, struct diff **,
168     struct diff3_state *);
169 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
170 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
171 static const struct got_error *edscript(int, struct diff3_state *);
172 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
173 static const struct got_error *prange(struct line_range *, 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 {
202 	const struct got_error *err = NULL;
203 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
204 	char *outpath = NULL;
205 	struct got_diff_state ds;
206 	struct got_diff_args args;
207 	int res;
208 
209 	*d = NULL;
210 
211 	f1 = fopen(path1, "r");
212 	if (f1 == NULL) {
213 		err = got_error_from_errno2("fopen", path1);
214 		goto done;
215 	}
216 	f2 = fopen(path2, "r");
217 	if (f1 == NULL) {
218 		err = got_error_from_errno2("fopen", path2);
219 		goto done;
220 	}
221 
222 	err = got_opentemp_named(&outpath, &outfile,
223 	    GOT_TMPDIR_STR "/got-diffreg");
224 	if (err)
225 		goto done;
226 
227 	memset(&ds, 0, sizeof(ds));
228 	/* XXX should stat buffers be passed in args instead of ds? */
229 	if (stat(path1, &ds.stb1) == -1) {
230 		err = got_error_from_errno2("stat", path1);
231 		goto done;
232 	}
233 	if (stat(path2, &ds.stb2) == -1) {
234 		err = got_error_from_errno2("stat", path2);
235 		goto done;
236 	}
237 
238 	memset(&args, 0, sizeof(args));
239 	args.diff_format = D_NORMAL;
240 	args.label[0] = "";
241 	args.label[1] = "";
242 	args.diff_context = 0;
243 
244 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
245 	    outfile, NULL);
246 	if (err)
247 		goto done;
248 
249 	if (fflush(outfile) != 0) {
250 		err = got_error_from_errno2("fflush", outpath);
251 		goto done;
252 	}
253 
254 	err = buf_load(d, outpath);
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) != 0 && err == NULL)
262 		err = got_error_from_errno("fclose");
263 	if (f1 && fclose(f1) != 0 && err == NULL)
264 		err = got_error_from_errno("fclose");
265 	if (f2 && fclose(f2) != 0 && 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, const char *p1, const char *p2,
275     const char *p3, const char *label1, const char *label2, const char *label3)
276 {
277 	const struct got_error *err = NULL;
278 	char *dp13, *dp23, *path1, *path2, *path3;
279 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
280 	u_char *data, *patch;
281 	size_t dlen, plen;
282 	struct diff3_state *d3s;
283 	int i;
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, p1);
296 	if (err)
297 		goto out;
298 	err = buf_load(&b2, p2);
299 	if (err)
300 		goto out;
301 	err = buf_load(&b3, p3);
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);
336 	if (err) {
337 		buf_free(diffb);
338 		diffb = NULL;
339 		goto out;
340 
341 	}
342 	err = diffreg(&d2, path2, path3);
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]) != 0 && 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, "r")) == NULL)
464 		return got_error_from_errno2("fopen", path1);
465 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
466 		return got_error_from_errno2("fopen", path2);
467 	if ((d3s->fp[2] = fopen(path3, "r")) == 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 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
564 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
565 				    lp, l_list);
566 				dlp = lp;
567 
568 				lp->l_lineno = start;
569 				lp = ndlp;
570 			}
571 		}
572 
573 		/*
574 		 * always resort lines as the markers might be put at the
575 		 * same line as we first started editing.
576 		 */
577 		lineno = 0;
578 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
579 			sort->l_lineno = lineno++;
580 		dlines->l_nblines = lineno - 1;
581 	}
582 
583 	return (0);
584 }
585 
586 /*
587  * Pick up the line numbers of all changes from one change file.
588  * (This puts the numbers in a vector, which is not strictly necessary,
589  * since the vector is processed in one sequential pass.
590  * The vector could be optimized out of existence)
591  */
592 static const struct got_error *
593 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
594 {
595 	const struct got_error *err = NULL;
596 	FILE *f;
597 	int a, b, c, d;
598 	char kind, *p;
599 	size_t i = 0;
600 
601 	*n = 0;
602 
603 	f = fopen(name, "r");
604 	if (f == NULL)
605 		return got_error_from_errno2("fopen", name);
606 	err = getchange(&p, f, d3s);
607 	if (err)
608 		goto done;
609 	for (i = 0; p; i++) {
610 		if (i >= d3s->szchanges - 1) {
611 			err = increase(d3s);
612 			if (err)
613 				goto done;
614 		}
615 		a = b = number(&p);
616 		if (*p == ',') {
617 			p++;
618 			b = number(&p);
619 		}
620 		kind = *p++;
621 		c = d = number(&p);
622 		if (*p == ',') {
623 			p++;
624 			d = number(&p);
625 		}
626 		if (kind == 'a')
627 			a++;
628 		if (kind == 'd')
629 			c++;
630 		b++;
631 		d++;
632 		(*dd)[i].old.from = a;
633 		(*dd)[i].old.to = b;
634 		(*dd)[i].new.from = c;
635 		(*dd)[i].new.to = d;
636 
637 		err = getchange(&p, f, d3s);
638 		if (err)
639 			goto done;
640 	}
641 
642 	if (i) {
643 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
644 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
645 	}
646 done:
647 	if (fclose(f) != 0 && err == NULL)
648 		err = got_error_from_errno("fclose");
649 	if (err == NULL)
650 		*n = i;
651 	return err;
652 }
653 
654 static int
655 number(char **lc)
656 {
657 	int nn;
658 
659 	nn = 0;
660 	while (isdigit((unsigned char)(**lc)))
661 		nn = nn*10 + *(*lc)++ - '0';
662 
663 	return (nn);
664 }
665 
666 static const struct got_error *
667 getchange(char **line, FILE *b, struct diff3_state *d3s)
668 {
669 	const struct got_error *err = NULL;
670 
671 	*line = NULL;
672 	do {
673 		if (*line && isdigit((unsigned char)(*line)[0]))
674 			return NULL;
675 		err = get_line(line, b, NULL, d3s);
676 		if (err)
677 			return err;
678 	} while (*line);
679 
680 	return NULL;
681 }
682 
683 static const struct got_error *
684 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
685 {
686 	const struct got_error *err = NULL;
687 	char *cp = NULL;
688 	size_t size;
689 	ssize_t len;
690 	char *new;
691 
692 	*ret = NULL;
693 
694 	len = getline(&cp, &size, b);
695 	if (len == -1) {
696 		if (ferror(b))
697 			err = got_error_from_errno("getline");
698 		goto done;
699 	}
700 
701 	if (cp[len - 1] != '\n') {
702 		len++;
703 		if (len + 1 > size) {
704 			new = realloc(cp, len + 1);
705 			if (new == NULL) {
706 				err = got_error_from_errno("realloc");
707 				goto done;
708 			}
709 			cp = new;
710 		}
711 		cp[len - 1] = '\n';
712 		cp[len] = '\0';
713 	}
714 
715 	free(d3s->buf);
716 	*ret = d3s->buf = cp;
717 	cp = NULL;
718 	if (n != NULL)
719 		*n = len;
720 done:
721 	free(cp);
722 	return err;
723 }
724 
725 static const struct got_error *
726 merge(size_t m1, size_t m2, struct diff3_state *d3s)
727 {
728 	const struct got_error *err = NULL;
729 	struct diff *d1, *d2;
730 	int dpl, j, t1, t2;
731 
732 	d1 = d3s->d13;
733 	d2 = d3s->d23;
734 	j = 0;
735 	for (;;) {
736 		t1 = (d1 < d3s->d13 + m1);
737 		t2 = (d2 < d3s->d23 + m2);
738 		if (!t1 && !t2)
739 			break;
740 
741 		/* first file is different from others */
742 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
743 			/* stuff peculiar to 1st file */
744 			d1++;
745 			continue;
746 		}
747 
748 		/* second file is different from others */
749 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
750 			d2++;
751 			continue;
752 		}
753 
754 		/*
755 		 * Merge overlapping changes in first file
756 		 * this happens after extension (see below).
757 		 */
758 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
759 			d1[1].old.from = d1->old.from;
760 			d1[1].new.from = d1->new.from;
761 			d1++;
762 			continue;
763 		}
764 
765 		/* merge overlapping changes in second */
766 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
767 			d2[1].old.from = d2->old.from;
768 			d2[1].new.from = d2->new.from;
769 			d2++;
770 			continue;
771 		}
772 		/* stuff peculiar to third file or different in all */
773 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
774 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
775 			if (err)
776 				return err;
777 
778 			/*
779 			 * dpl = 0 means all files differ
780 			 * dpl = 1 means files 1 and 2 identical
781 			 */
782 			err = edit(d1, dpl, &j, d3s);
783 			if (err)
784 				return err;
785 			d1++;
786 			d2++;
787 			continue;
788 		}
789 
790 		/*
791 		 * Overlapping changes from file 1 and 2; extend changes
792 		 * appropriately to make them coincide.
793 		 */
794 		if (d1->new.from < d2->new.from) {
795 			d2->old.from -= d2->new.from - d1->new.from;
796 			d2->new.from = d1->new.from;
797 		} else if (d2->new.from < d1->new.from) {
798 			d1->old.from -= d1->new.from - d2->new.from;
799 			d1->new.from = d2->new.from;
800 		}
801 		if (d1->new.to > d2->new.to) {
802 			d2->old.to += d1->new.to - d2->new.to;
803 			d2->new.to = d1->new.to;
804 		} else if (d2->new.to > d1->new.to) {
805 			d1->old.to += d2->new.to - d1->new.to;
806 			d1->new.to = d2->new.to;
807 		}
808 	}
809 
810 	return (edscript(j, d3s));
811 }
812 
813 /*
814  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
815  */
816 static const struct got_error *
817 prange(struct line_range *rold, struct diff3_state *d3s)
818 {
819 	const struct got_error *err = NULL;
820 
821 	if (rold->to <= rold->from) {
822 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
823 		if (err)
824 			return err;
825 	} else {
826 		err = diff_output(d3s->diffbuf, "%d", rold->from);
827 		if (err)
828 			return err;
829 		if (rold->to > rold->from + 1) {
830 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
831 			if (err)
832 				return err;
833 		}
834 		err = diff_output(d3s->diffbuf, "c\n");
835 		if (err)
836 			return err;
837 	}
838 
839 	return NULL;
840 }
841 
842 /*
843  * Skip to just before line number from in file "i".
844  * Return the number of bytes skipped in *nskipped.
845  */
846 static const struct got_error *
847 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
848 {
849 	const struct got_error *err = NULL;
850 	size_t len, n;
851 	char *line;
852 
853 	*nskipped = 0;
854 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
855 		err = get_line(&line, d3s->fp[i], &len, d3s);
856 		if (err)
857 			return err;
858 		d3s->cline[i]++;
859 	}
860 	*nskipped = n;
861 	return NULL;
862 }
863 
864 /*
865  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
866  * the same data as the new range (in file 2).
867  *
868  * If this change could overlap, remember start/end offsets in file 2 so we
869  * can write out the original lines of text if a merge conflict occurs.
870  */
871 static const struct got_error *
872 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
873     struct diff3_state *d3s)
874 {
875 	const struct got_error *err = NULL;
876 	int c,d;
877 	int nchar;
878 	int nline;
879 	size_t nskipped;
880 	off_t off;
881 
882 	*dpl = 0;
883 
884 	if (r1->to - r1->from != r2->to - r2->from)
885 		return NULL;
886 
887 	err = skip(&nskipped, 0, r1->from, d3s);
888 	if (err)
889 		return err;
890 	err = skip(&nskipped, 1, r2->from, d3s);
891 	if (err)
892 		return err;
893 
894 	off = ftello(d3s->fp[1]);
895 	if (off == -1)
896 		return got_error_from_errno("ftello");
897 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
898 
899 	nchar = 0;
900 	for (nline = 0; nline < r1->to - r1->from; nline++) {
901 		do {
902 			c = getc(d3s->fp[0]);
903 			if (c == EOF)
904 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
905 			d = getc(d3s->fp[1]);
906 			if (d == EOF)
907 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
908 			nchar++;
909 			if (c != d) {
910 				long orig_line_len = nchar;
911 				while (d != '\n') {
912 					d = getc(d3s->fp[1]);
913 					if (d == EOF)
914 						break;
915 					orig_line_len++;
916 				}
917 				if (orig_line_len > nchar &&
918 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
919 				    SEEK_CUR) == -1)
920 					return got_ferror(d3s->fp[1],
921 						GOT_ERR_IO);
922  				/* original lines end here */
923 				d3s->de[j + 1].oldo.to = off + orig_line_len;
924 				err = repos(nchar, d3s);
925 				if (err)
926 					return err;
927 				return NULL;
928 			}
929 		} while (c != '\n');
930 	}
931 	err = repos(nchar, d3s);
932 	if (err)
933 		return err;
934 	*dpl = 1;
935 	return NULL;
936 }
937 
938 static const struct got_error *
939 repos(int nchar, struct diff3_state *d3s)
940 {
941 	int i;
942 
943 	for (i = 0; i < 2; i++) {
944 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
945 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
946 	}
947 
948 	return NULL;
949 }
950 
951 /*
952  * collect an editing script for later regurgitation
953  */
954 static const struct got_error *
955 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
956 {
957 	const struct got_error *err = NULL;
958 	size_t nskipped;
959 
960 	if (((fdup + 1) & 3) == 0)
961 		return NULL;
962 	(*j)++;
963 	d3s->overlap[*j] = !fdup;
964 	if (!fdup)
965 		d3s->overlapcnt++;
966 	d3s->de[*j].old.from = diff->old.from;
967 	d3s->de[*j].old.to = diff->old.to;
968 
969 	err = skip(&nskipped, 2, diff->new.from, d3s);
970 	if (err)
971 		return err;
972 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
973 
974 	err = skip(&nskipped, 2, diff->new.to, d3s);
975 	if (err)
976 		return err;
977 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
978 	return NULL;
979 }
980 
981 /* regurgitate */
982 static const struct got_error *
983 edscript(int n, struct diff3_state *d3s)
984 {
985 	const struct got_error *err = NULL;
986 	size_t k, len;
987 	char block[BUFSIZ+1];
988 
989 	for (; n > 0; n--) {
990 		if (!d3s->overlap[n]) {
991 			err = prange(&d3s->de[n].old, d3s);
992 			if (err)
993 				return err;
994 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
995 			/* Output a block of 3-way diff base file content. */
996 			err = diff_output(d3s->diffbuf, "%da\n%s\n",
997 			    d3s->de[n].old.to - 1, d3s->f2mark);
998 			if (err)
999 				return err;
1000 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1001 			    == -1)
1002 				return got_error_from_errno("fseeko");
1003 			k = (size_t)(d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1004 			for (; k > 0; k -= len) {
1005 				len = k > BUFSIZ ? BUFSIZ : k;
1006 				if (fread(block, 1, len, d3s->fp[1]) != len)
1007 					return got_ferror(d3s->fp[1],
1008 					    GOT_ERR_IO);
1009 				block[len] = '\0';
1010 				err = diff_output(d3s->diffbuf, "%s", block);
1011 				if (err)
1012 					return err;
1013 			}
1014 			err = diff_output(d3s->diffbuf, "%s\n",
1015 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1016 			if (err)
1017 				return err;
1018  		} else {
1019  			err = diff_output(d3s->diffbuf, "%da\n%s\n",
1020 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1021 			if (err)
1022 				return err;
1023 		}
1024 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1025 		    == -1)
1026 			return got_error_from_errno("fseek");
1027 		k = (size_t)(d3s->de[n].newo.to - d3s->de[n].newo.from);
1028 		for (; k > 0; k -= len) {
1029 			len = k > BUFSIZ ? BUFSIZ : k;
1030 			if (fread(block, 1, len, d3s->fp[2]) != len)
1031 				return got_ferror(d3s->fp[2], GOT_ERR_IO);
1032 			block[len] = '\0';
1033 			err = diff_output(d3s->diffbuf, "%s", block);
1034 			if (err)
1035 				return err;
1036 		}
1037 
1038 		if (!d3s->overlap[n]) {
1039 			err = diff_output(d3s->diffbuf, ".\n");
1040 			if (err)
1041 				return err;
1042 		} else {
1043 			err = diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
1044 			if (err)
1045 				return err;
1046 			err = diff_output(d3s->diffbuf, "%da\n%s\n.\n",
1047 			    d3s->de[n].old.from - 1, d3s->f1mark);
1048 			if (err)
1049 				return err;
1050 		}
1051 	}
1052 
1053 	return NULL;
1054 }
1055 
1056 static const struct got_error *
1057 increase(struct diff3_state *d3s)
1058 {
1059 	size_t newsz, incr;
1060 	struct diff *d;
1061 	char *s;
1062 
1063 	/* are the memset(3) calls needed? */
1064 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1065 	incr = newsz - d3s->szchanges;
1066 
1067 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1068 	if (d == NULL)
1069 		return got_error_from_errno("reallocarray");
1070 	d3s->d13 = d;
1071 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1072 
1073 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1074 	if (d == NULL)
1075 		return got_error_from_errno("reallocarray");
1076 	d3s->d23 = d;
1077 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1078 
1079 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1080 	if (d == NULL)
1081 		return got_error_from_errno("reallocarray");
1082 	d3s->de = d;
1083 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1084 
1085 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1086 	if (s == NULL)
1087 		return got_error_from_errno("reallocarray");
1088 	d3s->overlap = s;
1089 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1090 	d3s->szchanges = newsz;
1091 
1092 	return NULL;
1093 }