op public repos

Blob

Date:: Mon May 29 06:40:28 2023 UTC
Message:: consistently use ten Xs in mkstemp(3) templates patch from Josiah Frentsos, thanks!
Actions:: History | Blame | Raw File
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 <sha1.h>
73 #include <sha2.h>
74 #include <stdio.h>
75 #include <stdarg.h>
76 #include <stdlib.h>
77 #include <string.h>
78 #include <time.h>
79 #include <unistd.h>
80 
81 #include "got_error.h"
82 #include "got_opentemp.h"
83 #include "got_object.h"
84 #include "got_diff.h"
85 
86 #include "buf.h"
87 #include "rcsutil.h"
88 #include "got_lib_diff.h"
89 
90 #ifndef nitems
91 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
92 #endif
93 
94 /* diff3 - 3-way differential file comparison */
95 
96 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
97  *
98  * d13 = diff report on f1 vs f3
99  * d23 = diff report on f2 vs f3
100  * f1, f2, f3 the 3 files
101  * if changes in f1 overlap with changes in f3, m1 and m3 are used
102  * to mark the overlaps; otherwise, the file names f1 and f3 are used
103  * (only for options E and X).
104  */
105 
106 /*
107  * "from" is first in range of changed lines; "to" is last+1
108  * from=to=line after point of insertion for added lines.
109  */
110 struct line_range {
111 	int from;
112 	int to;
113 };
114 
115 struct off_range {
116 	off_t from;
117 	off_t to;
118 };
119 
120 struct diff {
121 	struct line_range old;
122 	struct line_range new;
123 	struct off_range oldo;
124 	struct off_range newo;
125 };
126 
127 struct diff3_state {
128 	size_t szchanges;
129 
130 	struct diff *d13;
131 	struct diff *d23;
132 
133 	/*
134 	 * "de" is used to gather editing scripts.  These are later spewed out
135 	 * in reverse order.  Its first element must be all zero, the "new"
136 	 * component of "de" contains line positions, and "oldo" and "newo"
137 	 * components contain byte positions.
138 	 * Array overlap indicates which sections in "de" correspond to lines
139 	 * that are different in all three files.
140 	 */
141 	struct diff *de;
142 	char *overlap;
143 	int overlapcnt;
144 	FILE *fp[3];
145 	int cline[3];		/* # of the last-read line in each file (0-2) */
146 
147 	/*
148 	 * the latest known correspondence between line numbers of the 3 files
149 	 * is stored in last[1-3];
150 	 */
151 	int last[4];
152 	char f1mark[PATH_MAX];
153 	char f2mark[PATH_MAX];
154 	char f3mark[PATH_MAX];
155 
156 	char *buf;
157 
158 	BUF *diffbuf;
159 };
160 
161 
162 static const struct got_error *duplicate(int *, int, struct line_range *,
163     struct line_range *, struct diff3_state *);
164 static const struct got_error *edit(struct diff *, int, int *,
165     struct diff3_state *);
166 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
167 static const struct got_error *get_line(char **, FILE *, size_t *,
168     struct diff3_state *);
169 static int number(char **);
170 static const struct got_error *readin(size_t *, char *, struct diff **,
171     struct diff3_state *);
172 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
173 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
174 static const struct got_error *edscript(int, struct diff3_state *);
175 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
176 static const struct got_error *prange(struct line_range *,
177     struct diff3_state *);
178 static const struct got_error *repos(int, struct diff3_state *);
179 static const struct got_error *increase(struct diff3_state *);
180 static const struct got_error *diff3_internal(char *, char *, char *,
181     char *, char *, const char *, const char *, struct diff3_state *,
182     const char *, const char *, const char *);
183 
184 static const struct got_error *
185 diff_output(BUF *diffbuf, const char *fmt, ...)
186 {
187 	const struct got_error *err = NULL;
188 	va_list vap;
189 	int i;
190 	char *str;
191 	size_t newsize;
192 
193 	va_start(vap, fmt);
194 	i = vasprintf(&str, fmt, vap);
195 	va_end(vap);
196 	if (i == -1)
197 		return got_error_from_errno("vasprintf");
198 	err = buf_append(&newsize, diffbuf, str, strlen(str));
199 	free(str);
200 	return err;
201 }
202 
203 static const struct got_error*
204 diffreg(BUF **d, const char *path1, const char *path2,
205     enum got_diff_algorithm diff_algo)
206 {
207 	const struct got_error *err = NULL;
208 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
209 	char *outpath = NULL;
210 	struct got_diffreg_result *diffreg_result = NULL;
211 
212 	*d = NULL;
213 
214 	f1 = fopen(path1, "re");
215 	if (f1 == NULL) {
216 		err = got_error_from_errno2("fopen", path1);
217 		goto done;
218 	}
219 	f2 = fopen(path2, "re");
220 	if (f1 == NULL) {
221 		err = got_error_from_errno2("fopen", path2);
222 		goto done;
223 	}
224 
225 	err = got_opentemp_named(&outpath, &outfile,
226 	    GOT_TMPDIR_STR "/got-diffreg", "");
227 	if (err)
228 		goto done;
229 
230 	err = got_diffreg(&diffreg_result, f1, f2, diff_algo, 0, 0);
231 	if (err)
232 		goto done;
233 
234 	if (diffreg_result) {
235 		struct diff_result *diff_result = diffreg_result->result;
236 		int atomizer_flags = (diff_result->left->atomizer_flags |
237 		    diff_result->right->atomizer_flags);
238 		if ((atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA)) {
239 			err = got_error(GOT_ERR_FILE_BINARY);
240 			goto done;
241 		}
242 	}
243 
244 	err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
245 	    GOT_DIFF_OUTPUT_PLAIN, 0, outfile);
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 	if (fseek(outfile, 0L, SEEK_SET) == -1) {
254 		err = got_ferror(outfile, GOT_ERR_IO);
255 		goto done;
256 	}
257 
258 	err = buf_load(d, outfile);
259 done:
260 	if (outpath) {
261 		if (unlink(outpath) == -1 && err == NULL)
262 			err = got_error_from_errno2("unlink", outpath);
263 		free(outpath);
264 	}
265 	if (outfile && fclose(outfile) == EOF && err == NULL)
266 		err = got_error_from_errno("fclose");
267 	if (f1 && fclose(f1) == EOF && err == NULL)
268 		err = got_error_from_errno("fclose");
269 	if (f2 && fclose(f2) == EOF && err == NULL)
270 		err = got_error_from_errno("fclose");
271 	return err;
272 }
273 
274 /*
275  * For merge(1).
276  */
277 const struct got_error *
278 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
279     FILE *f3, const char *label1, const char *label2, const char *label3,
280     enum got_diff_algorithm diff_algo)
281 {
282 	const struct got_error *err = NULL;
283 	char *dp13, *dp23, *path1, *path2, *path3;
284 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
285 	u_char *data, *patch;
286 	size_t dlen, plen, i;
287 	struct diff3_state *d3s;
288 
289 	*overlapcnt = 0;
290 
291 	d3s = calloc(1, sizeof(*d3s));
292 	if (d3s == NULL)
293 		return got_error_from_errno("calloc");
294 
295 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
296 	dp13 = dp23 = path1 = path2 = path3 = NULL;
297 	data = patch = NULL;
298 
299 	err = buf_load(&b1, f1);
300 	if (err)
301 		goto out;
302 	err = buf_load(&b2, f2);
303 	if (err)
304 		goto out;
305 	err = buf_load(&b3, f3);
306 	if (err)
307 		goto out;
308 
309 	err = buf_alloc(&diffb, 128);
310 	if (err)
311 		goto out;
312 
313 	if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXXXX") == -1) {
314 		err = got_error_from_errno("asprintf");
315 		goto out;
316 	}
317 	if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXXXX") == -1) {
318 		err = got_error_from_errno("asprintf");
319 		goto out;
320 	}
321 	if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXXXX") == -1) {
322 		err = got_error_from_errno("asprintf");
323 		goto out;
324 	}
325 
326 	err = buf_write_stmp(b1, path1);
327 	if (err)
328 		goto out;
329 	err = buf_write_stmp(b2, path2);
330 	if (err)
331 		goto out;
332 	err = buf_write_stmp(b3, path3);
333 	if (err)
334 		goto out;
335 
336 	buf_free(b2);
337 	b2 = NULL;
338 
339 	err = diffreg(&d1, path1, path3, diff_algo);
340 	if (err) {
341 		buf_free(diffb);
342 		diffb = NULL;
343 		goto out;
344 
345 	}
346 	err = diffreg(&d2, path2, path3, diff_algo);
347 	if (err) {
348 		buf_free(diffb);
349 		diffb = NULL;
350 		goto out;
351 	}
352 
353 	if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
354 		err = got_error_from_errno("asprintf");
355 		goto out;
356 	}
357 	err = buf_write_stmp(d1, dp13);
358 	if (err)
359 		goto out;
360 
361 	buf_free(d1);
362 	d1 = NULL;
363 
364 	if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
365 		err = got_error_from_errno("asprintf");
366 		goto out;
367 	}
368 	err = buf_write_stmp(d2, dp23);
369 	if (err)
370 		goto out;
371 
372 	buf_free(d2);
373 	d2 = NULL;
374 
375 	d3s->diffbuf = diffb;
376 	err = diff3_internal(dp13, dp23, path1, path2, path3,
377 	    label1, label3, d3s, label1, label2, label3);
378 	if (err) {
379 		buf_free(diffb);
380 		diffb = NULL;
381 		goto out;
382 	}
383 
384 	plen = buf_len(diffb);
385 	patch = buf_release(diffb);
386 	dlen = buf_len(b1);
387 	data = buf_release(b1);
388 
389 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
390 out:
391 	buf_free(b2);
392 	buf_free(b3);
393 	buf_free(d1);
394 	buf_free(d2);
395 
396 	if (unlink(path1) == -1 && err == NULL)
397 		err = got_error_from_errno2("unlink", path1);
398 	if (unlink(path2) == -1 && err == NULL)
399 		err = got_error_from_errno2("unlink", path2);
400 	if (unlink(path3) == -1 && err == NULL)
401 		err = got_error_from_errno2("unlink", path3);
402 	if (unlink(dp13) == -1 && err == NULL)
403 		err = got_error_from_errno2("unlink", dp13);
404 	if (unlink(dp23) == -1 && err == NULL)
405 		err = got_error_from_errno2("unlink", dp23);
406 
407 	free(path1);
408 	free(path2);
409 	free(path3);
410 	free(dp13);
411 	free(dp23);
412 	free(data);
413 	free(patch);
414 
415 	for (i = 0; i < nitems(d3s->fp); i++) {
416 		if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
417 			err = got_error_from_errno("fclose");
418 	}
419 	if (err == NULL && diffb) {
420 		if (buf_write_fd(diffb, outfd) < 0)
421 			err = got_error_from_errno("buf_write_fd");
422 		*overlapcnt = d3s->overlapcnt;
423 	}
424 	free(d3s);
425 	buf_free(diffb);
426 	return err;
427 }
428 
429 static const struct got_error *
430 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
431     const char *fmark, const char *rmark, struct diff3_state *d3s,
432     const char *label1, const char *label2, const char *label3)
433 {
434 	const struct got_error *err = NULL;
435 	ssize_t m, n;
436 	int i;
437 
438 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
439 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
440 	    label1 ? " " : "", label1 ? label1 : "");
441 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
442 		return got_error(GOT_ERR_NO_SPACE);
443 
444 	i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
445 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
446 	    label2 ? " " : "", label2 ? label2 : "");
447 	if (i < 0 || i >= (int)sizeof(d3s->f2mark))
448 		return got_error(GOT_ERR_NO_SPACE);
449 
450 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
451 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
452 	    label3 ? " " : "", label3 ? label3 : "");
453 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
454 		return got_error(GOT_ERR_NO_SPACE);
455 
456 	err = increase(d3s);
457 	if (err)
458 		return err;
459 
460 	err = readin(&m, dp13, &d3s->d13, d3s);
461 	if (err)
462 		return err;
463 	err = readin(&n, dp23, &d3s->d23, d3s);
464 	if (err)
465 		return err;
466 
467 	if ((d3s->fp[0] = fopen(path1, "re")) == NULL)
468 		return got_error_from_errno2("fopen", path1);
469 	if ((d3s->fp[1] = fopen(path2, "re")) == NULL)
470 		return got_error_from_errno2("fopen", path2);
471 	if ((d3s->fp[2] = fopen(path3, "re")) == NULL)
472 		return got_error_from_errno2("fopen", path3);
473 
474 	return merge(m, n, d3s);
475 }
476 
477 static int
478 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
479 {
480 	char op, *ep;
481 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
482 	int start, end, i, lineno;
483 	u_char tmp;
484 
485 	dlp = TAILQ_FIRST(&(dlines->l_lines));
486 	lp = TAILQ_FIRST(&(plines->l_lines));
487 
488 	end = 0;
489 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
490 	    lp = TAILQ_NEXT(lp, l_list)) {
491 		/* Skip blank lines */
492 		if (lp->l_len < 2)
493 			continue;
494 
495 		/* NUL-terminate line buffer for strtol() safety. */
496 		tmp = lp->l_line[lp->l_len - 1];
497 		lp->l_line[lp->l_len - 1] = '\0';
498 
499 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
500 		op = lp->l_line[lp->l_len - 2];
501 		start = (int)strtol(lp->l_line, &ep, 10);
502 
503 		/* Restore the last byte of the buffer */
504 		lp->l_line[lp->l_len - 1] = tmp;
505 
506 		if (op == 'a') {
507 			if (start > dlines->l_nblines ||
508 			    start < 0 || *ep != 'a')
509 				return -1;
510 		} else if (op == 'c') {
511 			if (start > dlines->l_nblines ||
512 			    start < 0 || (*ep != ',' && *ep != 'c'))
513 				return -1;
514 
515 			if (*ep == ',') {
516 				ep++;
517 				end = (int)strtol(ep, &ep, 10);
518 				if (end < 0 || *ep != 'c')
519 					return -1;
520 			} else {
521 				end = start;
522 			}
523 		}
524 
525 
526 		for (;;) {
527 			if (dlp == NULL)
528 				break;
529 			if (dlp->l_lineno == start)
530 				break;
531 			if (dlp->l_lineno > start) {
532 				dlp = TAILQ_PREV(dlp, tqh, l_list);
533 			} else if (dlp->l_lineno < start) {
534 				ndlp = TAILQ_NEXT(dlp, l_list);
535 				if (ndlp->l_lineno > start)
536 					break;
537 				dlp = ndlp;
538 			}
539 		}
540 
541 		if (dlp == NULL)
542 			return -1;
543 
544 
545 		if (op == 'c') {
546 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
547 			for (i = 0; i <= (end - start); i++) {
548 				ndlp = TAILQ_NEXT(dlp, l_list);
549 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
550 				dlp = ndlp;
551 			}
552 			dlp = insert_after;
553 		}
554 
555 		if (op == 'a' || op == 'c') {
556 			for (;;) {
557 				ndlp = lp;
558 				lp = TAILQ_NEXT(lp, l_list);
559 				if (lp == NULL)
560 					return -1;
561 
562 				if (lp->l_len == 2 &&
563 				    lp->l_line[0] == '.' &&
564 				    lp->l_line[1] == '\n')
565 					break;
566 
567 				if (lp->l_line[0] == ':') {
568 					lp->l_line++;
569 					lp->l_len--;
570 				}
571 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
572 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
573 				    lp, l_list);
574 				dlp = lp;
575 
576 				lp->l_lineno = start;
577 				lp = ndlp;
578 			}
579 		}
580 
581 		/*
582 		 * always resort lines as the markers might be put at the
583 		 * same line as we first started editing.
584 		 */
585 		lineno = 0;
586 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
587 			sort->l_lineno = lineno++;
588 		dlines->l_nblines = lineno - 1;
589 	}
590 
591 	return (0);
592 }
593 
594 /*
595  * Pick up the line numbers of all changes from one change file.
596  * (This puts the numbers in a vector, which is not strictly necessary,
597  * since the vector is processed in one sequential pass.
598  * The vector could be optimized out of existence)
599  */
600 static const struct got_error *
601 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
602 {
603 	const struct got_error *err = NULL;
604 	FILE *f;
605 	int a, b, c, d;
606 	char kind, *p;
607 	size_t i = 0;
608 
609 	*n = 0;
610 
611 	f = fopen(name, "re");
612 	if (f == NULL)
613 		return got_error_from_errno2("fopen", name);
614 	err = getchange(&p, f, d3s);
615 	if (err)
616 		goto done;
617 	for (i = 0; p; i++) {
618 		if (i >= d3s->szchanges - 1) {
619 			err = increase(d3s);
620 			if (err)
621 				goto done;
622 		}
623 		a = b = number(&p);
624 		if (*p == ',') {
625 			p++;
626 			b = number(&p);
627 		}
628 		kind = *p++;
629 		c = d = number(&p);
630 		if (*p == ',') {
631 			p++;
632 			d = number(&p);
633 		}
634 		if (kind == 'a')
635 			a++;
636 		if (kind == 'd')
637 			c++;
638 		b++;
639 		d++;
640 		(*dd)[i].old.from = a;
641 		(*dd)[i].old.to = b;
642 		(*dd)[i].new.from = c;
643 		(*dd)[i].new.to = d;
644 
645 		err = getchange(&p, f, d3s);
646 		if (err)
647 			goto done;
648 	}
649 
650 	if (i) {
651 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
652 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
653 	}
654 done:
655 	if (fclose(f) == EOF && err == NULL)
656 		err = got_error_from_errno("fclose");
657 	if (err == NULL)
658 		*n = i;
659 	return err;
660 }
661 
662 static int
663 number(char **lc)
664 {
665 	int nn;
666 
667 	nn = 0;
668 	while (isdigit((unsigned char)(**lc)))
669 		nn = nn*10 + *(*lc)++ - '0';
670 
671 	return (nn);
672 }
673 
674 static const struct got_error *
675 getchange(char **line, FILE *b, struct diff3_state *d3s)
676 {
677 	const struct got_error *err = NULL;
678 
679 	*line = NULL;
680 	do {
681 		if (*line && isdigit((unsigned char)(*line)[0]))
682 			return NULL;
683 		err = get_line(line, b, NULL, d3s);
684 		if (err)
685 			return err;
686 	} while (*line);
687 
688 	return NULL;
689 }
690 
691 static const struct got_error *
692 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
693 {
694 	const struct got_error *err = NULL;
695 	char *cp = NULL;
696 	size_t size = 0;
697 	ssize_t len;
698 	char *new;
699 
700 	*ret = NULL;
701 	if (n != NULL)
702 		*n = 0;
703 
704 	len = getline(&cp, &size, b);
705 	if (len == -1) {
706 		if (ferror(b))
707 			err = got_error_from_errno("getline");
708 		goto done;
709 	}
710 
711 	if (cp[len - 1] != '\n') {
712 		len++;
713 		if (len + 1 > size) {
714 			new = realloc(cp, len + 1);
715 			if (new == NULL) {
716 				err = got_error_from_errno("realloc");
717 				goto done;
718 			}
719 			cp = new;
720 		}
721 		cp[len - 1] = '\n';
722 		cp[len] = '\0';
723 	}
724 
725 	free(d3s->buf);
726 	*ret = d3s->buf = cp;
727 	cp = NULL;
728 	if (n != NULL)
729 		*n = len;
730 done:
731 	free(cp);
732 	return err;
733 }
734 
735 static const struct got_error *
736 merge(size_t m1, size_t m2, struct diff3_state *d3s)
737 {
738 	const struct got_error *err = NULL;
739 	struct diff *d1, *d2;
740 	int dpl, j, t1, t2;
741 
742 	d1 = d3s->d13;
743 	d2 = d3s->d23;
744 	j = 0;
745 	for (;;) {
746 		t1 = (d1 < d3s->d13 + m1);
747 		t2 = (d2 < d3s->d23 + m2);
748 		if (!t1 && !t2)
749 			break;
750 
751 		/* first file is different from others */
752 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
753 			/* stuff peculiar to 1st file */
754 			d1++;
755 			continue;
756 		}
757 
758 		/* second file is different from others */
759 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
760 			d2++;
761 			continue;
762 		}
763 
764 		/*
765 		 * Merge overlapping changes in first file
766 		 * this happens after extension (see below).
767 		 */
768 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
769 			d1[1].old.from = d1->old.from;
770 			d1[1].new.from = d1->new.from;
771 			d1++;
772 			continue;
773 		}
774 
775 		/* merge overlapping changes in second */
776 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
777 			d2[1].old.from = d2->old.from;
778 			d2[1].new.from = d2->new.from;
779 			d2++;
780 			continue;
781 		}
782 		/* stuff peculiar to third file or different in all */
783 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
784 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
785 			if (err)
786 				return err;
787 
788 			/*
789 			 * dpl = 0 means all files differ
790 			 * dpl = 1 means files 1 and 2 identical
791 			 */
792 			err = edit(d1, dpl, &j, d3s);
793 			if (err)
794 				return err;
795 			d1++;
796 			d2++;
797 			continue;
798 		}
799 
800 		/*
801 		 * Overlapping changes from file 1 and 2; extend changes
802 		 * appropriately to make them coincide.
803 		 */
804 		if (d1->new.from < d2->new.from) {
805 			d2->old.from -= d2->new.from - d1->new.from;
806 			d2->new.from = d1->new.from;
807 		} else if (d2->new.from < d1->new.from) {
808 			d1->old.from -= d1->new.from - d2->new.from;
809 			d1->new.from = d2->new.from;
810 		}
811 		if (d1->new.to > d2->new.to) {
812 			d2->old.to += d1->new.to - d2->new.to;
813 			d2->new.to = d1->new.to;
814 		} else if (d2->new.to > d1->new.to) {
815 			d1->old.to += d2->new.to - d1->new.to;
816 			d1->new.to = d2->new.to;
817 		}
818 	}
819 
820 	return (edscript(j, d3s));
821 }
822 
823 /*
824  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
825  */
826 static const struct got_error *
827 prange(struct line_range *rold, struct diff3_state *d3s)
828 {
829 	const struct got_error *err = NULL;
830 
831 	if (rold->to <= rold->from) {
832 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
833 		if (err)
834 			return err;
835 	} else {
836 		err = diff_output(d3s->diffbuf, "%d", rold->from);
837 		if (err)
838 			return err;
839 		if (rold->to > rold->from + 1) {
840 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
841 			if (err)
842 				return err;
843 		}
844 		err = diff_output(d3s->diffbuf, "c\n");
845 		if (err)
846 			return err;
847 	}
848 
849 	return NULL;
850 }
851 
852 /*
853  * Skip to just before line number from in file "i".
854  * Return the number of bytes skipped in *nskipped.
855  */
856 static const struct got_error *
857 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
858 {
859 	const struct got_error *err = NULL;
860 	size_t len, n;
861 	char *line;
862 
863 	*nskipped = 0;
864 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
865 		err = get_line(&line, d3s->fp[i], &len, d3s);
866 		if (err)
867 			return err;
868 		d3s->cline[i]++;
869 	}
870 	*nskipped = n;
871 	return NULL;
872 }
873 
874 /*
875  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
876  * the same data as the new range (in file 2).
877  *
878  * If this change could overlap, remember start/end offsets in file 2 so we
879  * can write out the original lines of text if a merge conflict occurs.
880  */
881 static const struct got_error *
882 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
883     struct diff3_state *d3s)
884 {
885 	const struct got_error *err = NULL;
886 	int c,d;
887 	int nchar;
888 	int nline;
889 	size_t nskipped;
890 	off_t off;
891 
892 	*dpl = 0;
893 
894 	if (r1->to - r1->from != r2->to - r2->from)
895 		return NULL;
896 
897 	err = skip(&nskipped, 0, r1->from, d3s);
898 	if (err)
899 		return err;
900 	err = skip(&nskipped, 1, r2->from, d3s);
901 	if (err)
902 		return err;
903 
904 	off = ftello(d3s->fp[1]);
905 	if (off == -1)
906 		return got_error_from_errno("ftello");
907 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
908 
909 	nchar = 0;
910 	for (nline = 0; nline < r1->to - r1->from; nline++) {
911 		do {
912 			c = getc(d3s->fp[0]);
913 			d = getc(d3s->fp[1]);
914 			if (c == EOF && d == EOF)
915 				break;
916 			else if (c == EOF)
917 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
918 			else if (d == EOF)
919 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
920 			nchar++;
921 			if (c != d) {
922 				long orig_line_len = nchar;
923 				while (d != '\n') {
924 					d = getc(d3s->fp[1]);
925 					if (d == EOF)
926 						break;
927 					orig_line_len++;
928 				}
929 				if (orig_line_len > nchar &&
930 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
931 				    SEEK_CUR) == -1)
932 					return got_ferror(d3s->fp[1],
933 						GOT_ERR_IO);
934 				/* original lines end here */
935 				d3s->de[j + 1].oldo.to = off + orig_line_len;
936 				err = repos(nchar, d3s);
937 				if (err)
938 					return err;
939 				return NULL;
940 			}
941 		} while (c != '\n');
942 	}
943 
944 	/* original lines end here */
945 	d3s->de[j + 1].oldo.to = off + nchar;
946 
947 	err = repos(nchar, d3s);
948 	if (err)
949 		return err;
950 	*dpl = 1;
951 	return NULL;
952 }
953 
954 static const struct got_error *
955 repos(int nchar, struct diff3_state *d3s)
956 {
957 	int i;
958 
959 	for (i = 0; i < 2; i++) {
960 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
961 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
962 	}
963 
964 	return NULL;
965 }
966 
967 /*
968  * collect an editing script for later regurgitation
969  */
970 static const struct got_error *
971 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
972 {
973 	const struct got_error *err = NULL;
974 	size_t nskipped;
975 
976 	if (((fdup + 1) & 3) == 0)
977 		return NULL;
978 	(*j)++;
979 	d3s->overlap[*j] = !fdup;
980 	if (!fdup)
981 		d3s->overlapcnt++;
982 	d3s->de[*j].old.from = diff->old.from;
983 	d3s->de[*j].old.to = diff->old.to;
984 
985 	err = skip(&nskipped, 2, diff->new.from, d3s);
986 	if (err)
987 		return err;
988 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
989 
990 	err = skip(&nskipped, 2, diff->new.to, d3s);
991 	if (err)
992 		return err;
993 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
994 	return NULL;
995 }
996 
997 /* regurgitate */
998 static const struct got_error *
999 edscript(int n, struct diff3_state *d3s)
1000 {
1001 	const struct got_error *err = NULL;
1002 	off_t len;
1003 	char *line = NULL;
1004 	size_t linesize = 0;
1005 	ssize_t linelen = 0, k;
1006 
1007 	for (; n > 0; n--) {
1008 		if (!d3s->overlap[n]) {
1009 			err = prange(&d3s->de[n].old, d3s);
1010 			if (err)
1011 				return err;
1012 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
1013 			/* Output a block of 3-way diff base file content. */
1014 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1015 			    d3s->de[n].old.to - 1, d3s->f2mark);
1016 			if (err)
1017 				return err;
1018 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1019 			    == -1)
1020 				return got_error_from_errno("fseeko");
1021 			len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1022 			for (k = 0; k < (ssize_t)len; k += linelen) {
1023 				linelen = getline(&line, &linesize, d3s->fp[1]);
1024 				if (linelen == -1) {
1025 					if (feof(d3s->fp[1]))
1026 						break;
1027 					err = got_ferror(d3s->fp[1],
1028 					    GOT_ERR_IO);
1029 					goto done;
1030 				}
1031 				err = diff_output(d3s->diffbuf, ":%s", line);
1032 				if (err)
1033 					goto done;
1034 			}
1035 			err = diff_output(d3s->diffbuf, "%s%s\n",
1036 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1037 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1038 			if (err)
1039 				goto done;
1040 		} else {
1041 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1042 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1043 			if (err)
1044 				goto done;
1045 		}
1046 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1047 		    == -1) {
1048 			err = got_error_from_errno("fseek");
1049 			goto done;
1050 		}
1051 		len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1052 		for (k = 0; k < (ssize_t)len; k += linelen) {
1053 			linelen = getline(&line, &linesize, d3s->fp[2]);
1054 			if (linelen == -1) {
1055 				if (feof(d3s->fp[2]))
1056 					break;
1057 				err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1058 				goto done;
1059 			}
1060 			err = diff_output(d3s->diffbuf, ":%s", line);
1061 			if (err)
1062 				goto done;
1063 		}
1064 
1065 		if (!d3s->overlap[n]) {
1066 			err = diff_output(d3s->diffbuf, ".\n");
1067 			if (err)
1068 				goto done;
1069 		} else {
1070 			err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1071 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1072 			    d3s->f3mark);
1073 			if (err)
1074 				goto done;
1075 			err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1076 			    d3s->de[n].old.from - 1, d3s->f1mark);
1077 			if (err)
1078 				goto done;
1079 		}
1080 	}
1081 done:
1082 	free(line);
1083 	return err;
1084 }
1085 
1086 static const struct got_error *
1087 increase(struct diff3_state *d3s)
1088 {
1089 	size_t newsz, incr;
1090 	struct diff *d;
1091 	char *s;
1092 
1093 	/* are the memset(3) calls needed? */
1094 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1095 	incr = newsz - d3s->szchanges;
1096 
1097 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1098 	if (d == NULL)
1099 		return got_error_from_errno("reallocarray");
1100 	d3s->d13 = d;
1101 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1102 
1103 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1104 	if (d == NULL)
1105 		return got_error_from_errno("reallocarray");
1106 	d3s->d23 = d;
1107 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1108 
1109 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1110 	if (d == NULL)
1111 		return got_error_from_errno("reallocarray");
1112 	d3s->de = d;
1113 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1114 
1115 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1116 	if (s == NULL)
1117 		return got_error_from_errno("reallocarray");
1118 	d3s->overlap = s;
1119 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1120 	d3s->szchanges = newsz;
1121 
1122 	return NULL;
1123 }