Gotweb

Blob

Date:: Sat Nov 20 22:47:47 2021 UTC
Message:: preverse binary files during updates and merges
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 
69 #include <ctype.h>
70 #include <limits.h>
71 #include <stdio.h>
72 #include <stdarg.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <time.h>
76 #include <unistd.h>
77 
78 #include "got_error.h"
79 #include "got_opentemp.h"
80 #include "got_object.h"
81 
82 #include "buf.h"
83 #include "rcsutil.h"
84 #include "got_lib_diff.h"
85 
86 #ifndef nitems
87 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
88 #endif
89 
90 /* diff3 - 3-way differential file comparison */
91 
92 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
93  *
94  * d13 = diff report on f1 vs f3
95  * d23 = diff report on f2 vs f3
96  * f1, f2, f3 the 3 files
97  * if changes in f1 overlap with changes in f3, m1 and m3 are used
98  * to mark the overlaps; otherwise, the file names f1 and f3 are used
99  * (only for options E and X).
100  */
101 
102 /*
103  * "from" is first in range of changed lines; "to" is last+1
104  * from=to=line after point of insertion for added lines.
105  */
106 struct line_range {
107 	int from;
108 	int to;
109 };
110 
111 struct off_range {
112 	off_t from;
113 	off_t to;
114 };
115 
116 struct diff {
117 	struct line_range old;
118 	struct line_range new;
119 	struct off_range oldo;
120 	struct off_range newo;
121 };
122 
123 struct diff3_state {
124 	size_t szchanges;
125 
126 	struct diff *d13;
127 	struct diff *d23;
128 
129 	/*
130 	 * "de" is used to gather editing scripts.  These are later spewed out
131 	 * in reverse order.  Its first element must be all zero, the "new"
132 	 * component of "de" contains line positions, and "oldo" and "newo"
133 	 * components contain byte positions.
134 	 * Array overlap indicates which sections in "de" correspond to lines
135 	 * that are different in all three files.
136 	 */
137 	struct diff *de;
138 	char *overlap;
139 	int overlapcnt;
140 	FILE *fp[3];
141 	int cline[3];		/* # of the last-read line in each file (0-2) */
142 
143 	/*
144 	 * the latest known correspondence between line numbers of the 3 files
145 	 * is stored in last[1-3];
146 	 */
147 	int last[4];
148 	char f1mark[PATH_MAX];
149 	char f2mark[PATH_MAX];
150 	char f3mark[PATH_MAX];
151 
152 	char *buf;
153 
154 	BUF *diffbuf;
155 };
156 
157 
158 static const struct got_error *duplicate(int *, int, struct line_range *,
159     struct line_range *, struct diff3_state *);
160 static const struct got_error *edit(struct diff *, int, int *,
161     struct diff3_state *);
162 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
163 static const struct got_error *get_line(char **, FILE *, size_t *,
164     struct diff3_state *);
165 static int number(char **);
166 static const struct got_error *readin(size_t *, char *, struct diff **,
167     struct diff3_state *);
168 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
169 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
170 static const struct got_error *edscript(int, struct diff3_state *);
171 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
172 static const struct got_error *prange(struct line_range *, struct diff3_state *);
173 static const struct got_error *repos(int, struct diff3_state *);
174 static const struct got_error *increase(struct diff3_state *);
175 static const struct got_error *diff3_internal(char *, char *, char *,
176     char *, char *, const char *, const char *, struct diff3_state *,
177     const char *, const char *, const char *);
178 
179 static const struct got_error *
180 diff_output(BUF *diffbuf, const char *fmt, ...)
181 {
182 	const struct got_error *err = NULL;
183 	va_list vap;
184 	int i;
185 	char *str;
186 	size_t newsize;
187 
188 	va_start(vap, fmt);
189 	i = vasprintf(&str, fmt, vap);
190 	va_end(vap);
191 	if (i == -1)
192 		return got_error_from_errno("vasprintf");
193 	err = buf_append(&newsize, diffbuf, str, strlen(str));
194 	free(str);
195 	return err;
196 }
197 
198 static const struct got_error*
199 diffreg(BUF **d, const char *path1, const char *path2,
200     enum got_diff_algorithm diff_algo)
201 {
202 	const struct got_error *err = NULL;
203 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
204 	char *outpath = NULL;
205 	struct got_diffreg_result *diffreg_result = NULL;
206 
207 	*d = NULL;
208 
209 	f1 = fopen(path1, "r");
210 	if (f1 == NULL) {
211 		err = got_error_from_errno2("fopen", path1);
212 		goto done;
213 	}
214 	f2 = fopen(path2, "r");
215 	if (f1 == NULL) {
216 		err = got_error_from_errno2("fopen", path2);
217 		goto done;
218 	}
219 
220 	err = got_opentemp_named(&outpath, &outfile,
221 	    GOT_TMPDIR_STR "/got-diffreg");
222 	if (err)
223 		goto done;
224 
225 	err = got_diffreg(&diffreg_result, f1, f2, diff_algo, 0, 0);
226 	if (err)
227 		goto done;
228 
229 	if (diffreg_result) {
230 		struct diff_result *diff_result = diffreg_result->result;
231 		int atomizer_flags = (diff_result->left->atomizer_flags |
232 		    diff_result->right->atomizer_flags);
233 		if ((atomizer_flags & DIFF_ATOMIZER_FOUND_BINARY_DATA)) {
234 			err = got_error(GOT_ERR_FILE_BINARY);
235 			goto done;
236 		}
237 	}
238 
239 	err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
240 	    GOT_DIFF_OUTPUT_EDSCRIPT, 0, outfile);
241 	if (err)
242 		goto done;
243 
244 	if (fflush(outfile) != 0) {
245 		err = got_error_from_errno2("fflush", outpath);
246 		goto done;
247 	}
248 	if (fseek(outfile, 0L, SEEK_SET) == -1) {
249 		err = got_ferror(outfile, GOT_ERR_IO);
250 		goto done;
251 	}
252 
253 	err = buf_load(d, outfile);
254 done:
255 	if (outpath) {
256 		if (unlink(outpath) == -1 && err == NULL)
257 			err = got_error_from_errno2("unlink", outpath);
258 		free(outpath);
259 	}
260 	if (outfile && fclose(outfile) == EOF && err == NULL)
261 		err = got_error_from_errno("fclose");
262 	if (f1 && fclose(f1) == EOF && err == NULL)
263 		err = got_error_from_errno("fclose");
264 	if (f2 && fclose(f2) == EOF && err == NULL)
265 		err = got_error_from_errno("fclose");
266 	return err;
267 }
268 
269 /*
270  * For merge(1).
271  */
272 const struct got_error *
273 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
274     FILE *f3, const char *label1, const char *label2, const char *label3,
275     enum got_diff_algorithm diff_algo)
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, i;
282 	struct diff3_state *d3s;
283 
284 	*overlapcnt = 0;
285 
286 	d3s = calloc(1, sizeof(*d3s));
287 	if (d3s == NULL)
288 		return got_error_from_errno("calloc");
289 
290 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
291 	dp13 = dp23 = path1 = path2 = path3 = NULL;
292 	data = patch = NULL;
293 
294 	err = buf_load(&b1, f1);
295 	if (err)
296 		goto out;
297 	err = buf_load(&b2, f2);
298 	if (err)
299 		goto out;
300 	err = buf_load(&b3, f3);
301 	if (err)
302 		goto out;
303 
304 	err = buf_alloc(&diffb, 128);
305 	if (err)
306 		goto out;
307 
308 	if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXX") == -1) {
309 		err = got_error_from_errno("asprintf");
310 		goto out;
311 	}
312 	if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXX") == -1) {
313 		err = got_error_from_errno("asprintf");
314 		goto out;
315 	}
316 	if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXX") == -1) {
317 		err = got_error_from_errno("asprintf");
318 		goto out;
319 	}
320 
321 	err = buf_write_stmp(b1, path1);
322 	if (err)
323 		goto out;
324 	err = buf_write_stmp(b2, path2);
325 	if (err)
326 		goto out;
327 	err = buf_write_stmp(b3, path3);
328 	if (err)
329 		goto out;
330 
331 	buf_free(b2);
332 	b2 = NULL;
333 
334 	err = diffreg(&d1, path1, path3, diff_algo);
335 	if (err) {
336 		buf_free(diffb);
337 		diffb = NULL;
338 		goto out;
339 
340 	}
341 	err = diffreg(&d2, path2, path3, diff_algo);
342 	if (err) {
343 		buf_free(diffb);
344 		diffb = NULL;
345 		goto out;
346 	}
347 
348 	if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
349 		err = got_error_from_errno("asprintf");
350 		goto out;
351 	}
352 	err = buf_write_stmp(d1, dp13);
353 	if (err)
354 		goto out;
355 
356 	buf_free(d1);
357 	d1 = NULL;
358 
359 	if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
360 		err = got_error_from_errno("asprintf");
361 		goto out;
362 	}
363 	err = buf_write_stmp(d2, dp23);
364 	if (err)
365 		goto out;
366 
367 	buf_free(d2);
368 	d2 = NULL;
369 
370 	d3s->diffbuf = diffb;
371 	err = diff3_internal(dp13, dp23, path1, path2, path3,
372 	    label1, label3, d3s, label1, label2, label3);
373 	if (err) {
374 		buf_free(diffb);
375 		diffb = NULL;
376 		goto out;
377 	}
378 
379 	plen = buf_len(diffb);
380 	patch = buf_release(diffb);
381 	dlen = buf_len(b1);
382 	data = buf_release(b1);
383 
384 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
385 out:
386 	buf_free(b2);
387 	buf_free(b3);
388 	buf_free(d1);
389 	buf_free(d2);
390 
391 	if (unlink(path1) == -1 && err == NULL)
392 		err = got_error_from_errno2("unlink", path1);
393 	if (unlink(path2) == -1 && err == NULL)
394 		err = got_error_from_errno2("unlink", path2);
395 	if (unlink(path3) == -1 && err == NULL)
396 		err = got_error_from_errno2("unlink", path3);
397 	if (unlink(dp13) == -1 && err == NULL)
398 		err = got_error_from_errno2("unlink", dp13);
399 	if (unlink(dp23) == -1 && err == NULL)
400 		err = got_error_from_errno2("unlink", dp23);
401 
402 	free(path1);
403 	free(path2);
404 	free(path3);
405 	free(dp13);
406 	free(dp23);
407 	free(data);
408 	free(patch);
409 
410 	for (i = 0; i < nitems(d3s->fp); i++) {
411 		if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
412 			err = got_error_from_errno("fclose");
413 	}
414 	if (err == NULL && diffb) {
415 		if (buf_write_fd(diffb, outfd) < 0)
416 			err = got_error_from_errno("buf_write_fd");
417 		*overlapcnt = d3s->overlapcnt;
418 	}
419 	free(d3s);
420 	buf_free(diffb);
421 	return err;
422 }
423 
424 static const struct got_error *
425 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
426     const char *fmark, const char *rmark, struct diff3_state *d3s,
427     const char *label1, const char *label2, const char *label3)
428 {
429 	const struct got_error *err = NULL;
430 	ssize_t m, n;
431 	int i;
432 
433 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
434 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
435 	    label1 ? " " : "", label1 ? label1 : "");
436 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
437 		return got_error(GOT_ERR_NO_SPACE);
438 
439 	i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
440 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
441 	    label2 ? " " : "", label2 ? label2 : "");
442 	if (i < 0 || i >= (int)sizeof(d3s->f2mark))
443 		return got_error(GOT_ERR_NO_SPACE);
444 
445 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
446 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
447 	    label3 ? " " : "", label3 ? label3 : "");
448 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
449 		return got_error(GOT_ERR_NO_SPACE);
450 
451 	err = increase(d3s);
452 	if (err)
453 		return err;
454 
455 	err = readin(&m, dp13, &d3s->d13, d3s);
456 	if (err)
457 		return err;
458 	err = readin(&n, dp23, &d3s->d23, d3s);
459 	if (err)
460 		return err;
461 
462 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
463 		return got_error_from_errno2("fopen", path1);
464 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
465 		return got_error_from_errno2("fopen", path2);
466 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
467 		return got_error_from_errno2("fopen", path3);
468 
469 	return merge(m, n, d3s);
470 }
471 
472 static int
473 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
474 {
475 	char op, *ep;
476 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
477 	int start, end, i, lineno;
478 	u_char tmp;
479 
480 	dlp = TAILQ_FIRST(&(dlines->l_lines));
481 	lp = TAILQ_FIRST(&(plines->l_lines));
482 
483 	end = 0;
484 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
485 	    lp = TAILQ_NEXT(lp, l_list)) {
486 		/* Skip blank lines */
487 		if (lp->l_len < 2)
488 			continue;
489 
490 		/* NUL-terminate line buffer for strtol() safety. */
491 		tmp = lp->l_line[lp->l_len - 1];
492 		lp->l_line[lp->l_len - 1] = '\0';
493 
494 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
495 		op = lp->l_line[lp->l_len - 2];
496 		start = (int)strtol(lp->l_line, &ep, 10);
497 
498 		/* Restore the last byte of the buffer */
499 		lp->l_line[lp->l_len - 1] = tmp;
500 
501 		if (op == 'a') {
502 			if (start > dlines->l_nblines ||
503 			    start < 0 || *ep != 'a')
504 				return -1;
505 		} else if (op == 'c') {
506 			if (start > dlines->l_nblines ||
507 			    start < 0 || (*ep != ',' && *ep != 'c'))
508 				return -1;
509 
510 			if (*ep == ',') {
511 				ep++;
512 				end = (int)strtol(ep, &ep, 10);
513 				if (end < 0 || *ep != 'c')
514 					return -1;
515 			} else {
516 				end = start;
517 			}
518 		}
519 
520 
521 		for (;;) {
522 			if (dlp == NULL)
523 				break;
524 			if (dlp->l_lineno == start)
525 				break;
526 			if (dlp->l_lineno > start) {
527 				dlp = TAILQ_PREV(dlp, tqh, l_list);
528 			} else if (dlp->l_lineno < start) {
529 				ndlp = TAILQ_NEXT(dlp, l_list);
530 				if (ndlp->l_lineno > start)
531 					break;
532 				dlp = ndlp;
533 			}
534 		}
535 
536 		if (dlp == NULL)
537 			return -1;
538 
539 
540 		if (op == 'c') {
541 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
542 			for (i = 0; i <= (end - start); i++) {
543 				ndlp = TAILQ_NEXT(dlp, l_list);
544 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
545 				dlp = ndlp;
546 			}
547 			dlp = insert_after;
548 		}
549 
550 		if (op == 'a' || op == 'c') {
551 			for (;;) {
552 				ndlp = lp;
553 				lp = TAILQ_NEXT(lp, l_list);
554 				if (lp == NULL)
555 					return -1;
556 
557 				if (lp->l_len == 2 &&
558 				    lp->l_line[0] == '.' &&
559 				    lp->l_line[1] == '\n')
560 					break;
561 
562 				if (lp->l_line[0] == ':') {
563 					lp->l_line++;
564 					lp->l_len--;
565 				}
566 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
567 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
568 				    lp, l_list);
569 				dlp = lp;
570 
571 				lp->l_lineno = start;
572 				lp = ndlp;
573 			}
574 		}
575 
576 		/*
577 		 * always resort lines as the markers might be put at the
578 		 * same line as we first started editing.
579 		 */
580 		lineno = 0;
581 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
582 			sort->l_lineno = lineno++;
583 		dlines->l_nblines = lineno - 1;
584 	}
585 
586 	return (0);
587 }
588 
589 /*
590  * Pick up the line numbers of all changes from one change file.
591  * (This puts the numbers in a vector, which is not strictly necessary,
592  * since the vector is processed in one sequential pass.
593  * The vector could be optimized out of existence)
594  */
595 static const struct got_error *
596 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
597 {
598 	const struct got_error *err = NULL;
599 	FILE *f;
600 	int a, b, c, d;
601 	char kind, *p;
602 	size_t i = 0;
603 
604 	*n = 0;
605 
606 	f = fopen(name, "r");
607 	if (f == NULL)
608 		return got_error_from_errno2("fopen", name);
609 	err = getchange(&p, f, d3s);
610 	if (err)
611 		goto done;
612 	for (i = 0; p; i++) {
613 		if (i >= d3s->szchanges - 1) {
614 			err = increase(d3s);
615 			if (err)
616 				goto done;
617 		}
618 		a = b = number(&p);
619 		if (*p == ',') {
620 			p++;
621 			b = number(&p);
622 		}
623 		kind = *p++;
624 		c = d = number(&p);
625 		if (*p == ',') {
626 			p++;
627 			d = number(&p);
628 		}
629 		if (kind == 'a')
630 			a++;
631 		if (kind == 'd')
632 			c++;
633 		b++;
634 		d++;
635 		(*dd)[i].old.from = a;
636 		(*dd)[i].old.to = b;
637 		(*dd)[i].new.from = c;
638 		(*dd)[i].new.to = d;
639 
640 		err = getchange(&p, f, d3s);
641 		if (err)
642 			goto done;
643 	}
644 
645 	if (i) {
646 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
647 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
648 	}
649 done:
650 	if (fclose(f) == EOF && err == NULL)
651 		err = got_error_from_errno("fclose");
652 	if (err == NULL)
653 		*n = i;
654 	return err;
655 }
656 
657 static int
658 number(char **lc)
659 {
660 	int nn;
661 
662 	nn = 0;
663 	while (isdigit((unsigned char)(**lc)))
664 		nn = nn*10 + *(*lc)++ - '0';
665 
666 	return (nn);
667 }
668 
669 static const struct got_error *
670 getchange(char **line, FILE *b, struct diff3_state *d3s)
671 {
672 	const struct got_error *err = NULL;
673 
674 	*line = NULL;
675 	do {
676 		if (*line && isdigit((unsigned char)(*line)[0]))
677 			return NULL;
678 		err = get_line(line, b, NULL, d3s);
679 		if (err)
680 			return err;
681 	} while (*line);
682 
683 	return NULL;
684 }
685 
686 static const struct got_error *
687 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
688 {
689 	const struct got_error *err = NULL;
690 	char *cp = NULL;
691 	size_t size;
692 	ssize_t len;
693 	char *new;
694 
695 	*ret = NULL;
696 	if (n != NULL)
697 		*n = 0;
698 
699 	len = getline(&cp, &size, b);
700 	if (len == -1) {
701 		if (ferror(b))
702 			err = got_error_from_errno("getline");
703 		goto done;
704 	}
705 
706 	if (cp[len - 1] != '\n') {
707 		len++;
708 		if (len + 1 > size) {
709 			new = realloc(cp, len + 1);
710 			if (new == NULL) {
711 				err = got_error_from_errno("realloc");
712 				goto done;
713 			}
714 			cp = new;
715 		}
716 		cp[len - 1] = '\n';
717 		cp[len] = '\0';
718 	}
719 
720 	free(d3s->buf);
721 	*ret = d3s->buf = cp;
722 	cp = NULL;
723 	if (n != NULL)
724 		*n = len;
725 done:
726 	free(cp);
727 	return err;
728 }
729 
730 static const struct got_error *
731 merge(size_t m1, size_t m2, struct diff3_state *d3s)
732 {
733 	const struct got_error *err = NULL;
734 	struct diff *d1, *d2;
735 	int dpl, j, t1, t2;
736 
737 	d1 = d3s->d13;
738 	d2 = d3s->d23;
739 	j = 0;
740 	for (;;) {
741 		t1 = (d1 < d3s->d13 + m1);
742 		t2 = (d2 < d3s->d23 + m2);
743 		if (!t1 && !t2)
744 			break;
745 
746 		/* first file is different from others */
747 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
748 			/* stuff peculiar to 1st file */
749 			d1++;
750 			continue;
751 		}
752 
753 		/* second file is different from others */
754 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
755 			d2++;
756 			continue;
757 		}
758 
759 		/*
760 		 * Merge overlapping changes in first file
761 		 * this happens after extension (see below).
762 		 */
763 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
764 			d1[1].old.from = d1->old.from;
765 			d1[1].new.from = d1->new.from;
766 			d1++;
767 			continue;
768 		}
769 
770 		/* merge overlapping changes in second */
771 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
772 			d2[1].old.from = d2->old.from;
773 			d2[1].new.from = d2->new.from;
774 			d2++;
775 			continue;
776 		}
777 		/* stuff peculiar to third file or different in all */
778 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
779 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
780 			if (err)
781 				return err;
782 
783 			/*
784 			 * dpl = 0 means all files differ
785 			 * dpl = 1 means files 1 and 2 identical
786 			 */
787 			err = edit(d1, dpl, &j, d3s);
788 			if (err)
789 				return err;
790 			d1++;
791 			d2++;
792 			continue;
793 		}
794 
795 		/*
796 		 * Overlapping changes from file 1 and 2; extend changes
797 		 * appropriately to make them coincide.
798 		 */
799 		if (d1->new.from < d2->new.from) {
800 			d2->old.from -= d2->new.from - d1->new.from;
801 			d2->new.from = d1->new.from;
802 		} else if (d2->new.from < d1->new.from) {
803 			d1->old.from -= d1->new.from - d2->new.from;
804 			d1->new.from = d2->new.from;
805 		}
806 		if (d1->new.to > d2->new.to) {
807 			d2->old.to += d1->new.to - d2->new.to;
808 			d2->new.to = d1->new.to;
809 		} else if (d2->new.to > d1->new.to) {
810 			d1->old.to += d2->new.to - d1->new.to;
811 			d1->new.to = d2->new.to;
812 		}
813 	}
814 
815 	return (edscript(j, d3s));
816 }
817 
818 /*
819  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
820  */
821 static const struct got_error *
822 prange(struct line_range *rold, struct diff3_state *d3s)
823 {
824 	const struct got_error *err = NULL;
825 
826 	if (rold->to <= rold->from) {
827 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
828 		if (err)
829 			return err;
830 	} else {
831 		err = diff_output(d3s->diffbuf, "%d", rold->from);
832 		if (err)
833 			return err;
834 		if (rold->to > rold->from + 1) {
835 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
836 			if (err)
837 				return err;
838 		}
839 		err = diff_output(d3s->diffbuf, "c\n");
840 		if (err)
841 			return err;
842 	}
843 
844 	return NULL;
845 }
846 
847 /*
848  * Skip to just before line number from in file "i".
849  * Return the number of bytes skipped in *nskipped.
850  */
851 static const struct got_error *
852 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
853 {
854 	const struct got_error *err = NULL;
855 	size_t len, n;
856 	char *line;
857 
858 	*nskipped = 0;
859 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
860 		err = get_line(&line, d3s->fp[i], &len, d3s);
861 		if (err)
862 			return err;
863 		d3s->cline[i]++;
864 	}
865 	*nskipped = n;
866 	return NULL;
867 }
868 
869 /*
870  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
871  * the same data as the new range (in file 2).
872  *
873  * If this change could overlap, remember start/end offsets in file 2 so we
874  * can write out the original lines of text if a merge conflict occurs.
875  */
876 static const struct got_error *
877 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
878     struct diff3_state *d3s)
879 {
880 	const struct got_error *err = NULL;
881 	int c,d;
882 	int nchar;
883 	int nline;
884 	size_t nskipped;
885 	off_t off;
886 
887 	*dpl = 0;
888 
889 	if (r1->to - r1->from != r2->to - r2->from)
890 		return NULL;
891 
892 	err = skip(&nskipped, 0, r1->from, d3s);
893 	if (err)
894 		return err;
895 	err = skip(&nskipped, 1, r2->from, d3s);
896 	if (err)
897 		return err;
898 
899 	off = ftello(d3s->fp[1]);
900 	if (off == -1)
901 		return got_error_from_errno("ftello");
902 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
903 
904 	nchar = 0;
905 	for (nline = 0; nline < r1->to - r1->from; nline++) {
906 		do {
907 			c = getc(d3s->fp[0]);
908 			d = getc(d3s->fp[1]);
909 			if (c == EOF && d == EOF)
910 				break;
911 			else if (c == EOF)
912 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
913 			else if (d == EOF)
914 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
915 			nchar++;
916 			if (c != d) {
917 				long orig_line_len = nchar;
918 				while (d != '\n') {
919 					d = getc(d3s->fp[1]);
920 					if (d == EOF)
921 						break;
922 					orig_line_len++;
923 				}
924 				if (orig_line_len > nchar &&
925 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
926 				    SEEK_CUR) == -1)
927 					return got_ferror(d3s->fp[1],
928 						GOT_ERR_IO);
929 				/* original lines end here */
930 				d3s->de[j + 1].oldo.to = off + orig_line_len;
931 				err = repos(nchar, d3s);
932 				if (err)
933 					return err;
934 				return NULL;
935 			}
936 		} while (c != '\n');
937 	}
938 
939 	/* original lines end here */
940 	d3s->de[j + 1].oldo.to = off + nchar;
941 
942 	err = repos(nchar, d3s);
943 	if (err)
944 		return err;
945 	*dpl = 1;
946 	return NULL;
947 }
948 
949 static const struct got_error *
950 repos(int nchar, struct diff3_state *d3s)
951 {
952 	int i;
953 
954 	for (i = 0; i < 2; i++) {
955 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
956 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
957 	}
958 
959 	return NULL;
960 }
961 
962 /*
963  * collect an editing script for later regurgitation
964  */
965 static const struct got_error *
966 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
967 {
968 	const struct got_error *err = NULL;
969 	size_t nskipped;
970 
971 	if (((fdup + 1) & 3) == 0)
972 		return NULL;
973 	(*j)++;
974 	d3s->overlap[*j] = !fdup;
975 	if (!fdup)
976 		d3s->overlapcnt++;
977 	d3s->de[*j].old.from = diff->old.from;
978 	d3s->de[*j].old.to = diff->old.to;
979 
980 	err = skip(&nskipped, 2, diff->new.from, d3s);
981 	if (err)
982 		return err;
983 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
984 
985 	err = skip(&nskipped, 2, diff->new.to, d3s);
986 	if (err)
987 		return err;
988 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
989 	return NULL;
990 }
991 
992 /* regurgitate */
993 static const struct got_error *
994 edscript(int n, struct diff3_state *d3s)
995 {
996 	const struct got_error *err = NULL;
997 	off_t len;
998 	char *line = NULL;
999 	size_t linesize = 0;
1000 	ssize_t linelen = 0, k;
1001 
1002 	for (; n > 0; n--) {
1003 		if (!d3s->overlap[n]) {
1004 			err = prange(&d3s->de[n].old, d3s);
1005 			if (err)
1006 				return err;
1007 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
1008 			/* Output a block of 3-way diff base file content. */
1009 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1010 			    d3s->de[n].old.to - 1, d3s->f2mark);
1011 			if (err)
1012 				return err;
1013 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
1014 			    == -1)
1015 				return got_error_from_errno("fseeko");
1016 			len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1017 			for (k = 0; k < (ssize_t)len; k += linelen) {
1018 				linelen = getline(&line, &linesize, d3s->fp[1]);
1019 				if (linelen == -1) {
1020 					if (feof(d3s->fp[1]))
1021 						break;
1022 					err = got_ferror(d3s->fp[1],
1023 					    GOT_ERR_IO);
1024 					goto done;
1025 				}
1026 				err = diff_output(d3s->diffbuf, ":%s", line);
1027 				if (err)
1028 					goto done;
1029 			}
1030 			err = diff_output(d3s->diffbuf, "%s%s\n",
1031 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1032 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1033 			if (err)
1034 				goto done;
1035 		} else {
1036 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1037 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1038 			if (err)
1039 				goto done;
1040 		}
1041 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1042 		    == -1) {
1043 			err = got_error_from_errno("fseek");
1044 			goto done;
1045 		}
1046 		len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1047 		for (k = 0; k < (ssize_t)len; k += linelen) {
1048 			linelen = getline(&line, &linesize, d3s->fp[2]);
1049 			if (linelen == -1) {
1050 				if (feof(d3s->fp[2]))
1051 					break;
1052 				err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1053 				goto done;
1054 			}
1055 			err = diff_output(d3s->diffbuf, ":%s", line);
1056 			if (err)
1057 				goto done;
1058 		}
1059 
1060 		if (!d3s->overlap[n]) {
1061 			err = diff_output(d3s->diffbuf, ".\n");
1062 			if (err)
1063 				goto done;
1064 		} else {
1065 			err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1066 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1067 			    d3s->f3mark);
1068 			if (err)
1069 				goto done;
1070 			err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1071 			    d3s->de[n].old.from - 1, d3s->f1mark);
1072 			if (err)
1073 				goto done;
1074 		}
1075 	}
1076 done:
1077 	free(line);
1078 	return err;
1079 }
1080 
1081 static const struct got_error *
1082 increase(struct diff3_state *d3s)
1083 {
1084 	size_t newsz, incr;
1085 	struct diff *d;
1086 	char *s;
1087 
1088 	/* are the memset(3) calls needed? */
1089 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1090 	incr = newsz - d3s->szchanges;
1091 
1092 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1093 	if (d == NULL)
1094 		return got_error_from_errno("reallocarray");
1095 	d3s->d13 = d;
1096 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1097 
1098 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1099 	if (d == NULL)
1100 		return got_error_from_errno("reallocarray");
1101 	d3s->d23 = d;
1102 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1103 
1104 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1105 	if (d == NULL)
1106 		return got_error_from_errno("reallocarray");
1107 	d3s->de = d;
1108 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1109 
1110 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1111 	if (s == NULL)
1112 		return got_error_from_errno("reallocarray");
1113 	d3s->overlap = s;
1114 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1115 	d3s->szchanges = newsz;
1116 
1117 	return NULL;
1118 }