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 #include "got_diff.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 *,
174     struct diff3_state *);
175 static const struct got_error *repos(int, struct diff3_state *);
176 static const struct got_error *increase(struct diff3_state *);
177 static const struct got_error *diff3_internal(char *, char *, char *,
178     char *, char *, const char *, const char *, struct diff3_state *,
179     const char *, const char *, const char *);
180 
181 static const struct got_error *
182 diff_output(BUF *diffbuf, const char *fmt, ...)
183 {
184 	const struct got_error *err = NULL;
185 	va_list vap;
186 	int i;
187 	char *str;
188 	size_t newsize;
189 
190 	va_start(vap, fmt);
191 	i = vasprintf(&str, fmt, vap);
192 	va_end(vap);
193 	if (i == -1)
194 		return got_error_from_errno("vasprintf");
195 	err = buf_append(&newsize, diffbuf, str, strlen(str));
196 	free(str);
197 	return err;
198 }
199 
200 static const struct got_error*
201 diffreg(BUF **d, const char *path1, const char *path2,
202     enum got_diff_algorithm diff_algo)
203 {
204 	const struct got_error *err = NULL;
205 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
206 	char *outpath = NULL;
207 	struct got_diffreg_result *diffreg_result = NULL;
208 
209 	*d = NULL;
210 
211 	f1 = fopen(path1, "re");
212 	if (f1 == NULL) {
213 		err = got_error_from_errno2("fopen", path1);
214 		goto done;
215 	}
216 	f2 = fopen(path2, "re");
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 	err = got_diffreg(&diffreg_result, f1, f2, diff_algo, 0, 0);
228 	if (err)
229 		goto done;
230 
231 	if (diffreg_result) {
232 		struct diff_result *diff_result = diffreg_result->result;
233 		int atomizer_flags = (diff_result->left->atomizer_flags |
234 		    diff_result->right->atomizer_flags);
235 		if ((atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA)) {
236 			err = got_error(GOT_ERR_FILE_BINARY);
237 			goto done;
238 		}
239 	}
240 
241 	err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
242 	    GOT_DIFF_OUTPUT_EDSCRIPT, 0, outfile);
243 	if (err)
244 		goto done;
245 
246 	if (fflush(outfile) != 0) {
247 		err = got_error_from_errno2("fflush", outpath);
248 		goto done;
249 	}
250 	if (fseek(outfile, 0L, SEEK_SET) == -1) {
251 		err = got_ferror(outfile, GOT_ERR_IO);
252 		goto done;
253 	}
254 
255 	err = buf_load(d, outfile);
256 done:
257 	if (outpath) {
258 		if (unlink(outpath) == -1 && err == NULL)
259 			err = got_error_from_errno2("unlink", outpath);
260 		free(outpath);
261 	}
262 	if (outfile && fclose(outfile) == EOF && err == NULL)
263 		err = got_error_from_errno("fclose");
264 	if (f1 && fclose(f1) == EOF && err == NULL)
265 		err = got_error_from_errno("fclose");
266 	if (f2 && fclose(f2) == EOF && err == NULL)
267 		err = got_error_from_errno("fclose");
268 	return err;
269 }
270 
271 /*
272  * For merge(1).
273  */
274 const struct got_error *
275 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
276     FILE *f3, const char *label1, const char *label2, const char *label3,
277     enum got_diff_algorithm diff_algo)
278 {
279 	const struct got_error *err = NULL;
280 	char *dp13, *dp23, *path1, *path2, *path3;
281 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
282 	u_char *data, *patch;
283 	size_t dlen, plen, i;
284 	struct diff3_state *d3s;
285 
286 	*overlapcnt = 0;
287 
288 	d3s = calloc(1, sizeof(*d3s));
289 	if (d3s == NULL)
290 		return got_error_from_errno("calloc");
291 
292 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
293 	dp13 = dp23 = path1 = path2 = path3 = NULL;
294 	data = patch = NULL;
295 
296 	err = buf_load(&b1, f1);
297 	if (err)
298 		goto out;
299 	err = buf_load(&b2, f2);
300 	if (err)
301 		goto out;
302 	err = buf_load(&b3, f3);
303 	if (err)
304 		goto out;
305 
306 	err = buf_alloc(&diffb, 128);
307 	if (err)
308 		goto out;
309 
310 	if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXX") == -1) {
311 		err = got_error_from_errno("asprintf");
312 		goto out;
313 	}
314 	if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXX") == -1) {
315 		err = got_error_from_errno("asprintf");
316 		goto out;
317 	}
318 	if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXX") == -1) {
319 		err = got_error_from_errno("asprintf");
320 		goto out;
321 	}
322 
323 	err = buf_write_stmp(b1, path1);
324 	if (err)
325 		goto out;
326 	err = buf_write_stmp(b2, path2);
327 	if (err)
328 		goto out;
329 	err = buf_write_stmp(b3, path3);
330 	if (err)
331 		goto out;
332 
333 	buf_free(b2);
334 	b2 = NULL;
335 
336 	err = diffreg(&d1, path1, path3, diff_algo);
337 	if (err) {
338 		buf_free(diffb);
339 		diffb = NULL;
340 		goto out;
341 
342 	}
343 	err = diffreg(&d2, path2, path3, diff_algo);
344 	if (err) {
345 		buf_free(diffb);
346 		diffb = NULL;
347 		goto out;
348 	}
349 
350 	if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
351 		err = got_error_from_errno("asprintf");
352 		goto out;
353 	}
354 	err = buf_write_stmp(d1, dp13);
355 	if (err)
356 		goto out;
357 
358 	buf_free(d1);
359 	d1 = NULL;
360 
361 	if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
362 		err = got_error_from_errno("asprintf");
363 		goto out;
364 	}
365 	err = buf_write_stmp(d2, dp23);
366 	if (err)
367 		goto out;
368 
369 	buf_free(d2);
370 	d2 = NULL;
371 
372 	d3s->diffbuf = diffb;
373 	err = diff3_internal(dp13, dp23, path1, path2, path3,
374 	    label1, label3, d3s, label1, label2, label3);
375 	if (err) {
376 		buf_free(diffb);
377 		diffb = NULL;
378 		goto out;
379 	}
380 
381 	plen = buf_len(diffb);
382 	patch = buf_release(diffb);
383 	dlen = buf_len(b1);
384 	data = buf_release(b1);
385 
386 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
387 out:
388 	buf_free(b2);
389 	buf_free(b3);
390 	buf_free(d1);
391 	buf_free(d2);
392 
393 	if (unlink(path1) == -1 && err == NULL)
394 		err = got_error_from_errno2("unlink", path1);
395 	if (unlink(path2) == -1 && err == NULL)
396 		err = got_error_from_errno2("unlink", path2);
397 	if (unlink(path3) == -1 && err == NULL)
398 		err = got_error_from_errno2("unlink", path3);
399 	if (unlink(dp13) == -1 && err == NULL)
400 		err = got_error_from_errno2("unlink", dp13);
401 	if (unlink(dp23) == -1 && err == NULL)
402 		err = got_error_from_errno2("unlink", dp23);
403 
404 	free(path1);
405 	free(path2);
406 	free(path3);
407 	free(dp13);
408 	free(dp23);
409 	free(data);
410 	free(patch);
411 
412 	for (i = 0; i < nitems(d3s->fp); i++) {
413 		if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
414 			err = got_error_from_errno("fclose");
415 	}
416 	if (err == NULL && diffb) {
417 		if (buf_write_fd(diffb, outfd) < 0)
418 			err = got_error_from_errno("buf_write_fd");
419 		*overlapcnt = d3s->overlapcnt;
420 	}
421 	free(d3s);
422 	buf_free(diffb);
423 	return err;
424 }
425 
426 static const struct got_error *
427 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
428     const char *fmark, const char *rmark, struct diff3_state *d3s,
429     const char *label1, const char *label2, const char *label3)
430 {
431 	const struct got_error *err = NULL;
432 	ssize_t m, n;
433 	int i;
434 
435 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
436 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
437 	    label1 ? " " : "", label1 ? label1 : "");
438 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
439 		return got_error(GOT_ERR_NO_SPACE);
440 
441 	i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
442 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
443 	    label2 ? " " : "", label2 ? label2 : "");
444 	if (i < 0 || i >= (int)sizeof(d3s->f2mark))
445 		return got_error(GOT_ERR_NO_SPACE);
446 
447 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
448 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
449 	    label3 ? " " : "", label3 ? label3 : "");
450 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
451 		return got_error(GOT_ERR_NO_SPACE);
452 
453 	err = increase(d3s);
454 	if (err)
455 		return err;
456 
457 	err = readin(&m, dp13, &d3s->d13, d3s);
458 	if (err)
459 		return err;
460 	err = readin(&n, dp23, &d3s->d23, d3s);
461 	if (err)
462 		return err;
463 
464 	if ((d3s->fp[0] = fopen(path1, "re")) == NULL)
465 		return got_error_from_errno2("fopen", path1);
466 	if ((d3s->fp[1] = fopen(path2, "re")) == NULL)
467 		return got_error_from_errno2("fopen", path2);
468 	if ((d3s->fp[2] = fopen(path3, "re")) == NULL)
469 		return got_error_from_errno2("fopen", path3);
470 
471 	return merge(m, n, d3s);
472 }
473 
474 static int
475 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
476 {
477 	char op, *ep;
478 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
479 	int start, end, i, lineno;
480 	u_char tmp;
481 
482 	dlp = TAILQ_FIRST(&(dlines->l_lines));
483 	lp = TAILQ_FIRST(&(plines->l_lines));
484 
485 	end = 0;
486 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
487 	    lp = TAILQ_NEXT(lp, l_list)) {
488 		/* Skip blank lines */
489 		if (lp->l_len < 2)
490 			continue;
491 
492 		/* NUL-terminate line buffer for strtol() safety. */
493 		tmp = lp->l_line[lp->l_len - 1];
494 		lp->l_line[lp->l_len - 1] = '\0';
495 
496 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
497 		op = lp->l_line[lp->l_len - 2];
498 		start = (int)strtol(lp->l_line, &ep, 10);
499 
500 		/* Restore the last byte of the buffer */
501 		lp->l_line[lp->l_len - 1] = tmp;
502 
503 		if (op == 'a') {
504 			if (start > dlines->l_nblines ||
505 			    start < 0 || *ep != 'a')
506 				return -1;
507 		} else if (op == 'c') {
508 			if (start > dlines->l_nblines ||
509 			    start < 0 || (*ep != ',' && *ep != 'c'))
510 				return -1;
511 
512 			if (*ep == ',') {
513 				ep++;
514 				end = (int)strtol(ep, &ep, 10);
515 				if (end < 0 || *ep != 'c')
516 					return -1;
517 			} else {
518 				end = start;
519 			}
520 		}
521 
522 
523 		for (;;) {
524 			if (dlp == NULL)
525 				break;
526 			if (dlp->l_lineno == start)
527 				break;
528 			if (dlp->l_lineno > start) {
529 				dlp = TAILQ_PREV(dlp, tqh, l_list);
530 			} else if (dlp->l_lineno < start) {
531 				ndlp = TAILQ_NEXT(dlp, l_list);
532 				if (ndlp->l_lineno > start)
533 					break;
534 				dlp = ndlp;
535 			}
536 		}
537 
538 		if (dlp == NULL)
539 			return -1;
540 
541 
542 		if (op == 'c') {
543 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
544 			for (i = 0; i <= (end - start); i++) {
545 				ndlp = TAILQ_NEXT(dlp, l_list);
546 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
547 				dlp = ndlp;
548 			}
549 			dlp = insert_after;
550 		}
551 
552 		if (op == 'a' || op == 'c') {
553 			for (;;) {
554 				ndlp = lp;
555 				lp = TAILQ_NEXT(lp, l_list);
556 				if (lp == NULL)
557 					return -1;
558 
559 				if (lp->l_len == 2 &&
560 				    lp->l_line[0] == '.' &&
561 				    lp->l_line[1] == '\n')
562 					break;
563 
564 				if (lp->l_line[0] == ':') {
565 					lp->l_line++;
566 					lp->l_len--;
567 				}
568 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
569 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
570 				    lp, l_list);
571 				dlp = lp;
572 
573 				lp->l_lineno = start;
574 				lp = ndlp;
575 			}
576 		}
577 
578 		/*
579 		 * always resort lines as the markers might be put at the
580 		 * same line as we first started editing.
581 		 */
582 		lineno = 0;
583 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
584 			sort->l_lineno = lineno++;
585 		dlines->l_nblines = lineno - 1;
586 	}
587 
588 	return (0);
589 }
590 
591 /*
592  * Pick up the line numbers of all changes from one change file.
593  * (This puts the numbers in a vector, which is not strictly necessary,
594  * since the vector is processed in one sequential pass.
595  * The vector could be optimized out of existence)
596  */
597 static const struct got_error *
598 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
599 {
600 	const struct got_error *err = NULL;
601 	FILE *f;
602 	int a, b, c, d;
603 	char kind, *p;
604 	size_t i = 0;
605 
606 	*n = 0;
607 
608 	f = fopen(name, "re");
609 	if (f == NULL)
610 		return got_error_from_errno2("fopen", name);
611 	err = getchange(&p, f, d3s);
612 	if (err)
613 		goto done;
614 	for (i = 0; p; i++) {
615 		if (i >= d3s->szchanges - 1) {
616 			err = increase(d3s);
617 			if (err)
618 				goto done;
619 		}
620 		a = b = number(&p);
621 		if (*p == ',') {
622 			p++;
623 			b = number(&p);
624 		}
625 		kind = *p++;
626 		c = d = number(&p);
627 		if (*p == ',') {
628 			p++;
629 			d = number(&p);
630 		}
631 		if (kind == 'a')
632 			a++;
633 		if (kind == 'd')
634 			c++;
635 		b++;
636 		d++;
637 		(*dd)[i].old.from = a;
638 		(*dd)[i].old.to = b;
639 		(*dd)[i].new.from = c;
640 		(*dd)[i].new.to = d;
641 
642 		err = getchange(&p, f, d3s);
643 		if (err)
644 			goto done;
645 	}
646 
647 	if (i) {
648 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
649 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
650 	}
651 done:
652 	if (fclose(f) == EOF && err == NULL)
653 		err = got_error_from_errno("fclose");
654 	if (err == NULL)
655 		*n = i;
656 	return err;
657 }
658 
659 static int
660 number(char **lc)
661 {
662 	int nn;
663 
664 	nn = 0;
665 	while (isdigit((unsigned char)(**lc)))
666 		nn = nn*10 + *(*lc)++ - '0';
667 
668 	return (nn);
669 }
670 
671 static const struct got_error *
672 getchange(char **line, FILE *b, struct diff3_state *d3s)
673 {
674 	const struct got_error *err = NULL;
675 
676 	*line = NULL;
677 	do {
678 		if (*line && isdigit((unsigned char)(*line)[0]))
679 			return NULL;
680 		err = get_line(line, b, NULL, d3s);
681 		if (err)
682 			return err;
683 	} while (*line);
684 
685 	return NULL;
686 }
687 
688 static const struct got_error *
689 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
690 {
691 	const struct got_error *err = NULL;
692 	char *cp = NULL;
693 	size_t size;
694 	ssize_t len;
695 	char *new;
696 
697 	*ret = NULL;
698 	if (n != NULL)
699 		*n = 0;
700 
701 	len = getline(&cp, &size, b);
702 	if (len == -1) {
703 		if (ferror(b))
704 			err = got_error_from_errno("getline");
705 		goto done;
706 	}
707 
708 	if (cp[len - 1] != '\n') {
709 		len++;
710 		if (len + 1 > size) {
711 			new = realloc(cp, len + 1);
712 			if (new == NULL) {
713 				err = got_error_from_errno("realloc");
714 				goto done;
715 			}
716 			cp = new;
717 		}
718 		cp[len - 1] = '\n';
719 		cp[len] = '\0';
720 	}
721 
722 	free(d3s->buf);
723 	*ret = d3s->buf = cp;
724 	cp = NULL;
725 	if (n != NULL)
726 		*n = len;
727 done:
728 	free(cp);
729 	return err;
730 }
731 
732 static const struct got_error *
733 merge(size_t m1, size_t m2, struct diff3_state *d3s)
734 {
735 	const struct got_error *err = NULL;
736 	struct diff *d1, *d2;
737 	int dpl, j, t1, t2;
738 
739 	d1 = d3s->d13;
740 	d2 = d3s->d23;
741 	j = 0;
742 	for (;;) {
743 		t1 = (d1 < d3s->d13 + m1);
744 		t2 = (d2 < d3s->d23 + m2);
745 		if (!t1 && !t2)
746 			break;
747 
748 		/* first file is different from others */
749 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
750 			/* stuff peculiar to 1st file */
751 			d1++;
752 			continue;
753 		}
754 
755 		/* second file is different from others */
756 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
757 			d2++;
758 			continue;
759 		}
760 
761 		/*
762 		 * Merge overlapping changes in first file
763 		 * this happens after extension (see below).
764 		 */
765 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
766 			d1[1].old.from = d1->old.from;
767 			d1[1].new.from = d1->new.from;
768 			d1++;
769 			continue;
770 		}
771 
772 		/* merge overlapping changes in second */
773 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
774 			d2[1].old.from = d2->old.from;
775 			d2[1].new.from = d2->new.from;
776 			d2++;
777 			continue;
778 		}
779 		/* stuff peculiar to third file or different in all */
780 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
781 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
782 			if (err)
783 				return err;
784 
785 			/*
786 			 * dpl = 0 means all files differ
787 			 * dpl = 1 means files 1 and 2 identical
788 			 */
789 			err = edit(d1, dpl, &j, d3s);
790 			if (err)
791 				return err;
792 			d1++;
793 			d2++;
794 			continue;
795 		}
796 
797 		/*
798 		 * Overlapping changes from file 1 and 2; extend changes
799 		 * appropriately to make them coincide.
800 		 */
801 		if (d1->new.from < d2->new.from) {
802 			d2->old.from -= d2->new.from - d1->new.from;
803 			d2->new.from = d1->new.from;
804 		} else if (d2->new.from < d1->new.from) {
805 			d1->old.from -= d1->new.from - d2->new.from;
806 			d1->new.from = d2->new.from;
807 		}
808 		if (d1->new.to > d2->new.to) {
809 			d2->old.to += d1->new.to - d2->new.to;
810 			d2->new.to = d1->new.to;
811 		} else if (d2->new.to > d1->new.to) {
812 			d1->old.to += d2->new.to - d1->new.to;
813 			d1->new.to = d2->new.to;
814 		}
815 	}
816 
817 	return (edscript(j, d3s));
818 }
819 
820 /*
821  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
822  */
823 static const struct got_error *
824 prange(struct line_range *rold, struct diff3_state *d3s)
825 {
826 	const struct got_error *err = NULL;
827 
828 	if (rold->to <= rold->from) {
829 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
830 		if (err)
831 			return err;
832 	} else {
833 		err = diff_output(d3s->diffbuf, "%d", rold->from);
834 		if (err)
835 			return err;
836 		if (rold->to > rold->from + 1) {
837 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
838 			if (err)
839 				return err;
840 		}
841 		err = diff_output(d3s->diffbuf, "c\n");
842 		if (err)
843 			return err;
844 	}
845 
846 	return NULL;
847 }
848 
849 /*
850  * Skip to just before line number from in file "i".
851  * Return the number of bytes skipped in *nskipped.
852  */
853 static const struct got_error *
854 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
855 {
856 	const struct got_error *err = NULL;
857 	size_t len, n;
858 	char *line;
859 
860 	*nskipped = 0;
861 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
862 		err = get_line(&line, d3s->fp[i], &len, d3s);
863 		if (err)
864 			return err;
865 		d3s->cline[i]++;
866 	}
867 	*nskipped = n;
868 	return NULL;
869 }
870 
871 /*
872  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
873  * the same data as the new range (in file 2).
874  *
875  * If this change could overlap, remember start/end offsets in file 2 so we
876  * can write out the original lines of text if a merge conflict occurs.
877  */
878 static const struct got_error *
879 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
880     struct diff3_state *d3s)
881 {
882 	const struct got_error *err = NULL;
883 	int c,d;
884 	int nchar;
885 	int nline;
886 	size_t nskipped;
887 	off_t off;
888 
889 	*dpl = 0;
890 
891 	if (r1->to - r1->from != r2->to - r2->from)
892 		return NULL;
893 
894 	err = skip(&nskipped, 0, r1->from, d3s);
895 	if (err)
896 		return err;
897 	err = skip(&nskipped, 1, r2->from, d3s);
898 	if (err)
899 		return err;
900 
901 	off = ftello(d3s->fp[1]);
902 	if (off == -1)
903 		return got_error_from_errno("ftello");
904 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
905 
906 	nchar = 0;
907 	for (nline = 0; nline < r1->to - r1->from; nline++) {
908 		do {
909 			c = getc(d3s->fp[0]);
910 			d = getc(d3s->fp[1]);
911 			if (c == EOF && d == EOF)
912 				break;
913 			else if (c == EOF)
914 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
915 			else if (d == EOF)
916 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
917 			nchar++;
918 			if (c != d) {
919 				long orig_line_len = nchar;
920 				while (d != '\n') {
921 					d = getc(d3s->fp[1]);
922 					if (d == EOF)
923 						break;
924 					orig_line_len++;
925 				}
926 				if (orig_line_len > nchar &&
927 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
928 				    SEEK_CUR) == -1)
929 					return got_ferror(d3s->fp[1],
930 						GOT_ERR_IO);
931 				/* original lines end here */
932 				d3s->de[j + 1].oldo.to = off + orig_line_len;
933 				err = repos(nchar, d3s);
934 				if (err)
935 					return err;
936 				return NULL;
937 			}
938 		} while (c != '\n');
939 	}
940 
941 	/* original lines end here */
942 	d3s->de[j + 1].oldo.to = off + nchar;
943 
944 	err = repos(nchar, d3s);
945 	if (err)
946 		return err;
947 	*dpl = 1;
948 	return NULL;
949 }
950 
951 static const struct got_error *
952 repos(int nchar, struct diff3_state *d3s)
953 {
954 	int i;
955 
956 	for (i = 0; i < 2; i++) {
957 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
958 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
959 	}
960 
961 	return NULL;
962 }
963 
964 /*
965  * collect an editing script for later regurgitation
966  */
967 static const struct got_error *
968 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
969 {
970 	const struct got_error *err = NULL;
971 	size_t nskipped;
972 
973 	if (((fdup + 1) & 3) == 0)
974 		return NULL;
975 	(*j)++;
976 	d3s->overlap[*j] = !fdup;
977 	if (!fdup)
978 		d3s->overlapcnt++;
979 	d3s->de[*j].old.from = diff->old.from;
980 	d3s->de[*j].old.to = diff->old.to;
981 
982 	err = skip(&nskipped, 2, diff->new.from, d3s);
983 	if (err)
984 		return err;
985 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
986 
987 	err = skip(&nskipped, 2, diff->new.to, d3s);
988 	if (err)
989 		return err;
990 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
991 	return NULL;
992 }
993 
994 /* regurgitate */
995 static const struct got_error *
996 edscript(int n, struct diff3_state *d3s)
997 {
998 	const struct got_error *err = NULL;
999 	off_t len;
1000 	char *line = NULL;
1001 	size_t linesize = 0;
1002 	ssize_t linelen = 0, k;
1003 
1004 	for (; n > 0; n--) {
1005 		if (!d3s->overlap[n]) {
1006 			err = prange(&d3s->de[n].old, d3s);
1007 			if (err)
1008 				return err;
1009 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
1010 			/* Output a block of 3-way diff base file content. */
1011 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1012 			    d3s->de[n].old.to - 1, d3s->f2mark);
1013 			if (err)
1014 				return err;
1015 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1016 			    == -1)
1017 				return got_error_from_errno("fseeko");
1018 			len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1019 			for (k = 0; k < (ssize_t)len; k += linelen) {
1020 				linelen = getline(&line, &linesize, d3s->fp[1]);
1021 				if (linelen == -1) {
1022 					if (feof(d3s->fp[1]))
1023 						break;
1024 					err = got_ferror(d3s->fp[1],
1025 					    GOT_ERR_IO);
1026 					goto done;
1027 				}
1028 				err = diff_output(d3s->diffbuf, ":%s", line);
1029 				if (err)
1030 					goto done;
1031 			}
1032 			err = diff_output(d3s->diffbuf, "%s%s\n",
1033 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1034 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1035 			if (err)
1036 				goto done;
1037 		} else {
1038 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1039 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1040 			if (err)
1041 				goto done;
1042 		}
1043 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1044 		    == -1) {
1045 			err = got_error_from_errno("fseek");
1046 			goto done;
1047 		}
1048 		len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1049 		for (k = 0; k < (ssize_t)len; k += linelen) {
1050 			linelen = getline(&line, &linesize, d3s->fp[2]);
1051 			if (linelen == -1) {
1052 				if (feof(d3s->fp[2]))
1053 					break;
1054 				err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1055 				goto done;
1056 			}
1057 			err = diff_output(d3s->diffbuf, ":%s", line);
1058 			if (err)
1059 				goto done;
1060 		}
1061 
1062 		if (!d3s->overlap[n]) {
1063 			err = diff_output(d3s->diffbuf, ".\n");
1064 			if (err)
1065 				goto done;
1066 		} else {
1067 			err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1068 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1069 			    d3s->f3mark);
1070 			if (err)
1071 				goto done;
1072 			err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1073 			    d3s->de[n].old.from - 1, d3s->f1mark);
1074 			if (err)
1075 				goto done;
1076 		}
1077 	}
1078 done:
1079 	free(line);
1080 	return err;
1081 }
1082 
1083 static const struct got_error *
1084 increase(struct diff3_state *d3s)
1085 {
1086 	size_t newsz, incr;
1087 	struct diff *d;
1088 	char *s;
1089 
1090 	/* are the memset(3) calls needed? */
1091 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1092 	incr = newsz - d3s->szchanges;
1093 
1094 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1095 	if (d == NULL)
1096 		return got_error_from_errno("reallocarray");
1097 	d3s->d13 = d;
1098 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1099 
1100 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1101 	if (d == NULL)
1102 		return got_error_from_errno("reallocarray");
1103 	d3s->d23 = d;
1104 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1105 
1106 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1107 	if (d == NULL)
1108 		return got_error_from_errno("reallocarray");
1109 	d3s->de = d;
1110 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1111 
1112 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1113 	if (s == NULL)
1114 		return got_error_from_errno("reallocarray");
1115 	d3s->overlap = s;
1116 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1117 	d3s->szchanges = newsz;
1118 
1119 	return NULL;
1120 }