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Date:: Tue Oct 12 20:02:46 2021 UTC
Message:: fix a segfault in edscript() introduced by my previous commit Found by our cherrypick regression tests.
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1 /*	$OpenBSD: diff3.c,v 1.41 2016/10/18 21:06:52 millert Exp $	*/
2 
3 /*
4  * Copyright (C) Caldera International Inc.  2001-2002.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code and documentation must retain the above
11  *    copyright notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed or owned by Caldera
18  *	International, Inc.
19  * 4. Neither the name of Caldera International, Inc. nor the names of other
20  *    contributors may be used to endorse or promote products derived from
21  *    this software without specific prior written permission.
22  *
23  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
24  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
28  * INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
30  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
32  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
33  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34  * POSSIBILITY OF SUCH DAMAGE.
35  */
36 /*-
37  * Copyright (c) 1991, 1993
38  *	The Regents of the University of California.  All rights reserved.
39  *
40  * Redistribution and use in source and binary forms, with or without
41  * modification, are permitted provided that the following conditions
42  * are met:
43  * 1. Redistributions of source code must retain the above copyright
44  *    notice, this list of conditions and the following disclaimer.
45  * 2. Redistributions in binary form must reproduce the above copyright
46  *    notice, this list of conditions and the following disclaimer in the
47  *    documentation and/or other materials provided with the distribution.
48  * 3. Neither the name of the University nor the names of its contributors
49  *    may be used to endorse or promote products derived from this software
50  *    without specific prior written permission.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62  * SUCH DAMAGE.
63  *
64  *	@(#)diff3.c	8.1 (Berkeley) 6/6/93
65  */
66 
67 #include <sys/stat.h>
68 
69 #include <ctype.h>
70 #include <limits.h>
71 #include <stdio.h>
72 #include <stdarg.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <time.h>
76 #include <unistd.h>
77 
78 #include "got_error.h"
79 #include "got_opentemp.h"
80 #include "got_object.h"
81 
82 #include "buf.h"
83 #include "rcsutil.h"
84 #include "got_lib_diff.h"
85 
86 #ifndef nitems
87 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
88 #endif
89 
90 /* diff3 - 3-way differential file comparison */
91 
92 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
93  *
94  * d13 = diff report on f1 vs f3
95  * d23 = diff report on f2 vs f3
96  * f1, f2, f3 the 3 files
97  * if changes in f1 overlap with changes in f3, m1 and m3 are used
98  * to mark the overlaps; otherwise, the file names f1 and f3 are used
99  * (only for options E and X).
100  */
101 
102 /*
103  * "from" is first in range of changed lines; "to" is last+1
104  * from=to=line after point of insertion for added lines.
105  */
106 struct line_range {
107 	int from;
108 	int to;
109 };
110 
111 struct off_range {
112 	off_t from;
113 	off_t to;
114 };
115 
116 struct diff {
117 	struct line_range old;
118 	struct line_range new;
119 	struct off_range oldo;
120 	struct off_range newo;
121 };
122 
123 struct diff3_state {
124 	size_t szchanges;
125 
126 	struct diff *d13;
127 	struct diff *d23;
128 
129 	/*
130 	 * "de" is used to gather editing scripts.  These are later spewed out
131 	 * in reverse order.  Its first element must be all zero, the "new"
132 	 * component of "de" contains line positions, and "oldo" and "newo"
133 	 * components contain byte positions.
134 	 * Array overlap indicates which sections in "de" correspond to lines
135 	 * that are different in all three files.
136 	 */
137 	struct diff *de;
138 	char *overlap;
139 	int overlapcnt;
140 	FILE *fp[3];
141 	int cline[3];		/* # of the last-read line in each file (0-2) */
142 
143 	/*
144 	 * the latest known correspondence between line numbers of the 3 files
145 	 * is stored in last[1-3];
146 	 */
147 	int last[4];
148 	char f1mark[PATH_MAX];
149 	char f2mark[PATH_MAX];
150 	char f3mark[PATH_MAX];
151 
152 	char *buf;
153 
154 	BUF *diffbuf;
155 };
156 
157 
158 static const struct got_error *duplicate(int *, int, struct line_range *,
159     struct line_range *, struct diff3_state *);
160 static const struct got_error *edit(struct diff *, int, int *,
161     struct diff3_state *);
162 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
163 static const struct got_error *get_line(char **, FILE *, size_t *,
164     struct diff3_state *);
165 static int number(char **);
166 static const struct got_error *readin(size_t *, char *, struct diff **,
167     struct diff3_state *);
168 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
169 static const struct got_error *skip(size_t *, int, int, struct diff3_state *);
170 static const struct got_error *edscript(int, struct diff3_state *);
171 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
172 static const struct got_error *prange(struct line_range *, 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, 1);
226 	if (err)
227 		goto done;
228 
229 	err = got_diffreg_output(NULL, NULL, diffreg_result, 1, 1, "", "",
230 	    GOT_DIFF_OUTPUT_EDSCRIPT, 0, outfile);
231 	if (err)
232 		goto done;
233 
234 	if (fflush(outfile) != 0) {
235 		err = got_error_from_errno2("fflush", outpath);
236 		goto done;
237 	}
238 	if (fseek(outfile, 0L, SEEK_SET) == -1) {
239 		err = got_ferror(outfile, GOT_ERR_IO);
240 		goto done;
241 	}
242 
243 	err = buf_load(d, outfile);
244 done:
245 	if (outpath) {
246 		if (unlink(outpath) == -1 && err == NULL)
247 			err = got_error_from_errno2("unlink", outpath);
248 		free(outpath);
249 	}
250 	if (outfile && fclose(outfile) == EOF && err == NULL)
251 		err = got_error_from_errno("fclose");
252 	if (f1 && fclose(f1) == EOF && err == NULL)
253 		err = got_error_from_errno("fclose");
254 	if (f2 && fclose(f2) == EOF && err == NULL)
255 		err = got_error_from_errno("fclose");
256 	return err;
257 }
258 
259 /*
260  * For merge(1).
261  */
262 const struct got_error *
263 got_merge_diff3(int *overlapcnt, int outfd, FILE *f1, FILE *f2,
264     FILE *f3, const char *label1, const char *label2, const char *label3,
265     enum got_diff_algorithm diff_algo)
266 {
267 	const struct got_error *err = NULL;
268 	char *dp13, *dp23, *path1, *path2, *path3;
269 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
270 	u_char *data, *patch;
271 	size_t dlen, plen, i;
272 	struct diff3_state *d3s;
273 
274 	*overlapcnt = 0;
275 
276 	d3s = calloc(1, sizeof(*d3s));
277 	if (d3s == NULL)
278 		return got_error_from_errno("calloc");
279 
280 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
281 	dp13 = dp23 = path1 = path2 = path3 = NULL;
282 	data = patch = NULL;
283 
284 	err = buf_load(&b1, f1);
285 	if (err)
286 		goto out;
287 	err = buf_load(&b2, f2);
288 	if (err)
289 		goto out;
290 	err = buf_load(&b3, f3);
291 	if (err)
292 		goto out;
293 
294 	err = buf_alloc(&diffb, 128);
295 	if (err)
296 		goto out;
297 
298 	if (asprintf(&path1, GOT_TMPDIR_STR "/got-diff1.XXXXXXXX") == -1) {
299 		err = got_error_from_errno("asprintf");
300 		goto out;
301 	}
302 	if (asprintf(&path2, GOT_TMPDIR_STR "/got-diff2.XXXXXXXX") == -1) {
303 		err = got_error_from_errno("asprintf");
304 		goto out;
305 	}
306 	if (asprintf(&path3, GOT_TMPDIR_STR "/got-diff3.XXXXXXXX") == -1) {
307 		err = got_error_from_errno("asprintf");
308 		goto out;
309 	}
310 
311 	err = buf_write_stmp(b1, path1);
312 	if (err)
313 		goto out;
314 	err = buf_write_stmp(b2, path2);
315 	if (err)
316 		goto out;
317 	err = buf_write_stmp(b3, path3);
318 	if (err)
319 		goto out;
320 
321 	buf_free(b2);
322 	b2 = NULL;
323 
324 	err = diffreg(&d1, path1, path3, diff_algo);
325 	if (err) {
326 		buf_free(diffb);
327 		diffb = NULL;
328 		goto out;
329 
330 	}
331 	err = diffreg(&d2, path2, path3, diff_algo);
332 	if (err) {
333 		buf_free(diffb);
334 		diffb = NULL;
335 		goto out;
336 	}
337 
338 	if (asprintf(&dp13, GOT_TMPDIR_STR "/got-d13.XXXXXXXXXX") == -1) {
339 		err = got_error_from_errno("asprintf");
340 		goto out;
341 	}
342 	err = buf_write_stmp(d1, dp13);
343 	if (err)
344 		goto out;
345 
346 	buf_free(d1);
347 	d1 = NULL;
348 
349 	if (asprintf(&dp23, GOT_TMPDIR_STR "/got-d23.XXXXXXXXXX") == -1) {
350 		err = got_error_from_errno("asprintf");
351 		goto out;
352 	}
353 	err = buf_write_stmp(d2, dp23);
354 	if (err)
355 		goto out;
356 
357 	buf_free(d2);
358 	d2 = NULL;
359 
360 	d3s->diffbuf = diffb;
361 	err = diff3_internal(dp13, dp23, path1, path2, path3,
362 	    label1, label3, d3s, label1, label2, label3);
363 	if (err) {
364 		buf_free(diffb);
365 		diffb = NULL;
366 		goto out;
367 	}
368 
369 	plen = buf_len(diffb);
370 	patch = buf_release(diffb);
371 	dlen = buf_len(b1);
372 	data = buf_release(b1);
373 
374 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
375 out:
376 	buf_free(b2);
377 	buf_free(b3);
378 	buf_free(d1);
379 	buf_free(d2);
380 
381 	if (unlink(path1) == -1 && err == NULL)
382 		err = got_error_from_errno2("unlink", path1);
383 	if (unlink(path2) == -1 && err == NULL)
384 		err = got_error_from_errno2("unlink", path2);
385 	if (unlink(path3) == -1 && err == NULL)
386 		err = got_error_from_errno2("unlink", path3);
387 	if (unlink(dp13) == -1 && err == NULL)
388 		err = got_error_from_errno2("unlink", dp13);
389 	if (unlink(dp23) == -1 && err == NULL)
390 		err = got_error_from_errno2("unlink", dp23);
391 
392 	free(path1);
393 	free(path2);
394 	free(path3);
395 	free(dp13);
396 	free(dp23);
397 	free(data);
398 	free(patch);
399 
400 	for (i = 0; i < nitems(d3s->fp); i++) {
401 		if (d3s->fp[i] && fclose(d3s->fp[i]) == EOF && err == NULL)
402 			err = got_error_from_errno("fclose");
403 	}
404 	if (err == NULL && diffb) {
405 		if (buf_write_fd(diffb, outfd) < 0)
406 			err = got_error_from_errno("buf_write_fd");
407 		*overlapcnt = d3s->overlapcnt;
408 	}
409 	free(d3s);
410 	buf_free(diffb);
411 	return err;
412 }
413 
414 static const struct got_error *
415 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
416     const char *fmark, const char *rmark, struct diff3_state *d3s,
417     const char *label1, const char *label2, const char *label3)
418 {
419 	const struct got_error *err = NULL;
420 	ssize_t m, n;
421 	int i;
422 
423 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
424 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_BEGIN,
425 	    label1 ? " " : "", label1 ? label1 : "");
426 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
427 		return got_error(GOT_ERR_NO_SPACE);
428 
429 	i = snprintf(d3s->f2mark, sizeof(d3s->f2mark),
430 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_ORIG,
431 	    label2 ? " " : "", label2 ? label2 : "");
432 	if (i < 0 || i >= (int)sizeof(d3s->f2mark))
433 		return got_error(GOT_ERR_NO_SPACE);
434 
435 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
436 	    "%s%s%s", GOT_DIFF_CONFLICT_MARKER_END,
437 	    label3 ? " " : "", label3 ? label3 : "");
438 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
439 		return got_error(GOT_ERR_NO_SPACE);
440 
441 	err = increase(d3s);
442 	if (err)
443 		return err;
444 
445 	err = readin(&m, dp13, &d3s->d13, d3s);
446 	if (err)
447 		return err;
448 	err = readin(&n, dp23, &d3s->d23, d3s);
449 	if (err)
450 		return err;
451 
452 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
453 		return got_error_from_errno2("fopen", path1);
454 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
455 		return got_error_from_errno2("fopen", path2);
456 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
457 		return got_error_from_errno2("fopen", path3);
458 
459 	return merge(m, n, d3s);
460 }
461 
462 static int
463 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
464 {
465 	char op, *ep;
466 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
467 	int start, end, i, lineno;
468 	u_char tmp;
469 
470 	dlp = TAILQ_FIRST(&(dlines->l_lines));
471 	lp = TAILQ_FIRST(&(plines->l_lines));
472 
473 	end = 0;
474 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
475 	    lp = TAILQ_NEXT(lp, l_list)) {
476 		/* Skip blank lines */
477 		if (lp->l_len < 2)
478 			continue;
479 
480 		/* NUL-terminate line buffer for strtol() safety. */
481 		tmp = lp->l_line[lp->l_len - 1];
482 		lp->l_line[lp->l_len - 1] = '\0';
483 
484 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
485 		op = lp->l_line[lp->l_len - 2];
486 		start = (int)strtol(lp->l_line, &ep, 10);
487 
488 		/* Restore the last byte of the buffer */
489 		lp->l_line[lp->l_len - 1] = tmp;
490 
491 		if (op == 'a') {
492 			if (start > dlines->l_nblines ||
493 			    start < 0 || *ep != 'a')
494 				return -1;
495 		} else if (op == 'c') {
496 			if (start > dlines->l_nblines ||
497 			    start < 0 || (*ep != ',' && *ep != 'c'))
498 				return -1;
499 
500 			if (*ep == ',') {
501 				ep++;
502 				end = (int)strtol(ep, &ep, 10);
503 				if (end < 0 || *ep != 'c')
504 					return -1;
505 			} else {
506 				end = start;
507 			}
508 		}
509 
510 
511 		for (;;) {
512 			if (dlp == NULL)
513 				break;
514 			if (dlp->l_lineno == start)
515 				break;
516 			if (dlp->l_lineno > start) {
517 				dlp = TAILQ_PREV(dlp, tqh, l_list);
518 			} else if (dlp->l_lineno < start) {
519 				ndlp = TAILQ_NEXT(dlp, l_list);
520 				if (ndlp->l_lineno > start)
521 					break;
522 				dlp = ndlp;
523 			}
524 		}
525 
526 		if (dlp == NULL)
527 			return -1;
528 
529 
530 		if (op == 'c') {
531 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
532 			for (i = 0; i <= (end - start); i++) {
533 				ndlp = TAILQ_NEXT(dlp, l_list);
534 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
535 				dlp = ndlp;
536 			}
537 			dlp = insert_after;
538 		}
539 
540 		if (op == 'a' || op == 'c') {
541 			for (;;) {
542 				ndlp = lp;
543 				lp = TAILQ_NEXT(lp, l_list);
544 				if (lp == NULL)
545 					return -1;
546 
547 				if (lp->l_len == 2 &&
548 				    lp->l_line[0] == '.' &&
549 				    lp->l_line[1] == '\n')
550 					break;
551 
552 				if (lp->l_line[0] == ':') {
553 					lp->l_line++;
554 					lp->l_len--;
555 				}
556 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
557 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
558 				    lp, l_list);
559 				dlp = lp;
560 
561 				lp->l_lineno = start;
562 				lp = ndlp;
563 			}
564 		}
565 
566 		/*
567 		 * always resort lines as the markers might be put at the
568 		 * same line as we first started editing.
569 		 */
570 		lineno = 0;
571 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
572 			sort->l_lineno = lineno++;
573 		dlines->l_nblines = lineno - 1;
574 	}
575 
576 	return (0);
577 }
578 
579 /*
580  * Pick up the line numbers of all changes from one change file.
581  * (This puts the numbers in a vector, which is not strictly necessary,
582  * since the vector is processed in one sequential pass.
583  * The vector could be optimized out of existence)
584  */
585 static const struct got_error *
586 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
587 {
588 	const struct got_error *err = NULL;
589 	FILE *f;
590 	int a, b, c, d;
591 	char kind, *p;
592 	size_t i = 0;
593 
594 	*n = 0;
595 
596 	f = fopen(name, "r");
597 	if (f == NULL)
598 		return got_error_from_errno2("fopen", name);
599 	err = getchange(&p, f, d3s);
600 	if (err)
601 		goto done;
602 	for (i = 0; p; i++) {
603 		if (i >= d3s->szchanges - 1) {
604 			err = increase(d3s);
605 			if (err)
606 				goto done;
607 		}
608 		a = b = number(&p);
609 		if (*p == ',') {
610 			p++;
611 			b = number(&p);
612 		}
613 		kind = *p++;
614 		c = d = number(&p);
615 		if (*p == ',') {
616 			p++;
617 			d = number(&p);
618 		}
619 		if (kind == 'a')
620 			a++;
621 		if (kind == 'd')
622 			c++;
623 		b++;
624 		d++;
625 		(*dd)[i].old.from = a;
626 		(*dd)[i].old.to = b;
627 		(*dd)[i].new.from = c;
628 		(*dd)[i].new.to = d;
629 
630 		err = getchange(&p, f, d3s);
631 		if (err)
632 			goto done;
633 	}
634 
635 	if (i) {
636 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
637 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
638 	}
639 done:
640 	if (fclose(f) == EOF && err == NULL)
641 		err = got_error_from_errno("fclose");
642 	if (err == NULL)
643 		*n = i;
644 	return err;
645 }
646 
647 static int
648 number(char **lc)
649 {
650 	int nn;
651 
652 	nn = 0;
653 	while (isdigit((unsigned char)(**lc)))
654 		nn = nn*10 + *(*lc)++ - '0';
655 
656 	return (nn);
657 }
658 
659 static const struct got_error *
660 getchange(char **line, FILE *b, struct diff3_state *d3s)
661 {
662 	const struct got_error *err = NULL;
663 
664 	*line = NULL;
665 	do {
666 		if (*line && isdigit((unsigned char)(*line)[0]))
667 			return NULL;
668 		err = get_line(line, b, NULL, d3s);
669 		if (err)
670 			return err;
671 	} while (*line);
672 
673 	return NULL;
674 }
675 
676 static const struct got_error *
677 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
678 {
679 	const struct got_error *err = NULL;
680 	char *cp = NULL;
681 	size_t size;
682 	ssize_t len;
683 	char *new;
684 
685 	*ret = NULL;
686 
687 	len = getline(&cp, &size, b);
688 	if (len == -1) {
689 		if (ferror(b))
690 			err = got_error_from_errno("getline");
691 		goto done;
692 	}
693 
694 	if (cp[len - 1] != '\n') {
695 		len++;
696 		if (len + 1 > size) {
697 			new = realloc(cp, len + 1);
698 			if (new == NULL) {
699 				err = got_error_from_errno("realloc");
700 				goto done;
701 			}
702 			cp = new;
703 		}
704 		cp[len - 1] = '\n';
705 		cp[len] = '\0';
706 	}
707 
708 	free(d3s->buf);
709 	*ret = d3s->buf = cp;
710 	cp = NULL;
711 	if (n != NULL)
712 		*n = len;
713 done:
714 	free(cp);
715 	return err;
716 }
717 
718 static const struct got_error *
719 merge(size_t m1, size_t m2, struct diff3_state *d3s)
720 {
721 	const struct got_error *err = NULL;
722 	struct diff *d1, *d2;
723 	int dpl, j, t1, t2;
724 
725 	d1 = d3s->d13;
726 	d2 = d3s->d23;
727 	j = 0;
728 	for (;;) {
729 		t1 = (d1 < d3s->d13 + m1);
730 		t2 = (d2 < d3s->d23 + m2);
731 		if (!t1 && !t2)
732 			break;
733 
734 		/* first file is different from others */
735 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
736 			/* stuff peculiar to 1st file */
737 			d1++;
738 			continue;
739 		}
740 
741 		/* second file is different from others */
742 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
743 			d2++;
744 			continue;
745 		}
746 
747 		/*
748 		 * Merge overlapping changes in first file
749 		 * this happens after extension (see below).
750 		 */
751 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
752 			d1[1].old.from = d1->old.from;
753 			d1[1].new.from = d1->new.from;
754 			d1++;
755 			continue;
756 		}
757 
758 		/* merge overlapping changes in second */
759 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
760 			d2[1].old.from = d2->old.from;
761 			d2[1].new.from = d2->new.from;
762 			d2++;
763 			continue;
764 		}
765 		/* stuff peculiar to third file or different in all */
766 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
767 			err = duplicate(&dpl, j, &d1->old, &d2->old, d3s);
768 			if (err)
769 				return err;
770 
771 			/*
772 			 * dpl = 0 means all files differ
773 			 * dpl = 1 means files 1 and 2 identical
774 			 */
775 			err = edit(d1, dpl, &j, d3s);
776 			if (err)
777 				return err;
778 			d1++;
779 			d2++;
780 			continue;
781 		}
782 
783 		/*
784 		 * Overlapping changes from file 1 and 2; extend changes
785 		 * appropriately to make them coincide.
786 		 */
787 		if (d1->new.from < d2->new.from) {
788 			d2->old.from -= d2->new.from - d1->new.from;
789 			d2->new.from = d1->new.from;
790 		} else if (d2->new.from < d1->new.from) {
791 			d1->old.from -= d1->new.from - d2->new.from;
792 			d1->new.from = d2->new.from;
793 		}
794 		if (d1->new.to > d2->new.to) {
795 			d2->old.to += d1->new.to - d2->new.to;
796 			d2->new.to = d1->new.to;
797 		} else if (d2->new.to > d1->new.to) {
798 			d1->old.to += d2->new.to - d1->new.to;
799 			d1->new.to = d2->new.to;
800 		}
801 	}
802 
803 	return (edscript(j, d3s));
804 }
805 
806 /*
807  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
808  */
809 static const struct got_error *
810 prange(struct line_range *rold, struct diff3_state *d3s)
811 {
812 	const struct got_error *err = NULL;
813 
814 	if (rold->to <= rold->from) {
815 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
816 		if (err)
817 			return err;
818 	} else {
819 		err = diff_output(d3s->diffbuf, "%d", rold->from);
820 		if (err)
821 			return err;
822 		if (rold->to > rold->from + 1) {
823 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
824 			if (err)
825 				return err;
826 		}
827 		err = diff_output(d3s->diffbuf, "c\n");
828 		if (err)
829 			return err;
830 	}
831 
832 	return NULL;
833 }
834 
835 /*
836  * Skip to just before line number from in file "i".
837  * Return the number of bytes skipped in *nskipped.
838  */
839 static const struct got_error *
840 skip(size_t *nskipped, int i, int from, struct diff3_state *d3s)
841 {
842 	const struct got_error *err = NULL;
843 	size_t len, n;
844 	char *line;
845 
846 	*nskipped = 0;
847 	for (n = 0; d3s->cline[i] < from - 1; n += len) {
848 		err = get_line(&line, d3s->fp[i], &len, d3s);
849 		if (err)
850 			return err;
851 		d3s->cline[i]++;
852 	}
853 	*nskipped = n;
854 	return NULL;
855 }
856 
857 /*
858  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
859  * the same data as the new range (in file 2).
860  *
861  * If this change could overlap, remember start/end offsets in file 2 so we
862  * can write out the original lines of text if a merge conflict occurs.
863  */
864 static const struct got_error *
865 duplicate(int *dpl, int j, struct line_range *r1, struct line_range *r2,
866     struct diff3_state *d3s)
867 {
868 	const struct got_error *err = NULL;
869 	int c,d;
870 	int nchar;
871 	int nline;
872 	size_t nskipped;
873 	off_t off;
874 
875 	*dpl = 0;
876 
877 	if (r1->to - r1->from != r2->to - r2->from)
878 		return NULL;
879 
880 	err = skip(&nskipped, 0, r1->from, d3s);
881 	if (err)
882 		return err;
883 	err = skip(&nskipped, 1, r2->from, d3s);
884 	if (err)
885 		return err;
886 
887 	off = ftello(d3s->fp[1]);
888 	if (off == -1)
889 		return got_error_from_errno("ftello");
890 	d3s->de[j + 1].oldo.from = off; /* original lines start here */
891 
892 	nchar = 0;
893 	for (nline = 0; nline < r1->to - r1->from; nline++) {
894 		do {
895 			c = getc(d3s->fp[0]);
896 			d = getc(d3s->fp[1]);
897 			if (c == EOF && d == EOF)
898 				break;
899 			else if (c == EOF)
900 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
901 			else if (d == EOF)
902 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
903 			nchar++;
904 			if (c != d) {
905 				long orig_line_len = nchar;
906 				while (d != '\n') {
907 					d = getc(d3s->fp[1]);
908 					if (d == EOF)
909 						break;
910 					orig_line_len++;
911 				}
912 				if (orig_line_len > nchar &&
913 				    fseek(d3s->fp[1], -(orig_line_len - nchar),
914 				    SEEK_CUR) == -1)
915 					return got_ferror(d3s->fp[1],
916 						GOT_ERR_IO);
917 				/* original lines end here */
918 				d3s->de[j + 1].oldo.to = off + orig_line_len;
919 				err = repos(nchar, d3s);
920 				if (err)
921 					return err;
922 				return NULL;
923 			}
924 		} while (c != '\n');
925 	}
926 	err = repos(nchar, d3s);
927 	if (err)
928 		return err;
929 	*dpl = 1;
930 	return NULL;
931 }
932 
933 static const struct got_error *
934 repos(int nchar, struct diff3_state *d3s)
935 {
936 	int i;
937 
938 	for (i = 0; i < 2; i++) {
939 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
940 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
941 	}
942 
943 	return NULL;
944 }
945 
946 /*
947  * collect an editing script for later regurgitation
948  */
949 static const struct got_error *
950 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
951 {
952 	const struct got_error *err = NULL;
953 	size_t nskipped;
954 
955 	if (((fdup + 1) & 3) == 0)
956 		return NULL;
957 	(*j)++;
958 	d3s->overlap[*j] = !fdup;
959 	if (!fdup)
960 		d3s->overlapcnt++;
961 	d3s->de[*j].old.from = diff->old.from;
962 	d3s->de[*j].old.to = diff->old.to;
963 
964 	err = skip(&nskipped, 2, diff->new.from, d3s);
965 	if (err)
966 		return err;
967 	d3s->de[*j].newo.from = d3s->de[*j - 1].newo.to + nskipped;
968 
969 	err = skip(&nskipped, 2, diff->new.to, d3s);
970 	if (err)
971 		return err;
972 	d3s->de[*j].newo.to = d3s->de[*j].newo.from + nskipped;
973 	return NULL;
974 }
975 
976 /* regurgitate */
977 static const struct got_error *
978 edscript(int n, struct diff3_state *d3s)
979 {
980 	const struct got_error *err = NULL;
981 	off_t len;
982 	char *line = NULL;
983 	size_t linesize = 0;
984 	ssize_t linelen = 0, k;
985 
986 	for (; n > 0; n--) {
987 		if (!d3s->overlap[n]) {
988 			err = prange(&d3s->de[n].old, d3s);
989 			if (err)
990 				return err;
991 		} else if (d3s->de[n].oldo.from < d3s->de[n].oldo.to) {
992 			/* Output a block of 3-way diff base file content. */
993 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
994 			    d3s->de[n].old.to - 1, d3s->f2mark);
995 			if (err)
996 				return err;
997 			if (fseeko(d3s->fp[1], d3s->de[n].oldo.from, SEEK_SET)
998 			    == -1)
999 				return got_error_from_errno("fseeko");
1000 			len = (d3s->de[n].oldo.to - d3s->de[n].oldo.from);
1001 			for (k = 0; k < (ssize_t)len; k += linelen) {
1002 				linelen = getline(&line, &linesize, d3s->fp[1]);
1003 				if (linelen == -1) {
1004 					if (feof(d3s->fp[1]))
1005 						break;
1006 					err = got_ferror(d3s->fp[1],
1007 					    GOT_ERR_IO);
1008 					goto done;
1009 				}
1010 				err = diff_output(d3s->diffbuf, ":%s", line);
1011 				if (err)
1012 					goto done;
1013 			}
1014 			err = diff_output(d3s->diffbuf, "%s%s\n",
1015 			    linelen > 0 && line[linelen] == '\n' ? ":" : "",
1016 			    GOT_DIFF_CONFLICT_MARKER_SEP);
1017 			if (err)
1018 				goto done;
1019 		} else {
1020 			err = diff_output(d3s->diffbuf, "%da\n:%s\n",
1021 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
1022 			if (err)
1023 				goto done;
1024 		}
1025 		if (fseeko(d3s->fp[2], d3s->de[n].newo.from, SEEK_SET)
1026 		    == -1) {
1027 			err = got_error_from_errno("fseek");
1028 			goto done;
1029 		}
1030 		len = (d3s->de[n].newo.to - d3s->de[n].newo.from);
1031 		for (k = 0; k < (ssize_t)len; k += linelen) {
1032 			linelen = getline(&line, &linesize, d3s->fp[2]);
1033 			if (linelen == -1) {
1034 				if (feof(d3s->fp[2]))
1035 					break;
1036 				err = got_ferror(d3s->fp[2], GOT_ERR_IO);
1037 				goto done;
1038 			}
1039 			err = diff_output(d3s->diffbuf, ":%s", line);
1040 			if (err)
1041 				goto done;
1042 		}
1043 
1044 		if (!d3s->overlap[n]) {
1045 			err = diff_output(d3s->diffbuf, ".\n");
1046 			if (err)
1047 				goto done;
1048 		} else {
1049 			err = diff_output(d3s->diffbuf, "%s%s\n.\n",
1050 			    line[linelen] == '\n' ? ":" : "",
1051 			    d3s->f3mark);
1052 			if (err)
1053 				goto done;
1054 			err = diff_output(d3s->diffbuf, "%da\n:%s\n.\n",
1055 			    d3s->de[n].old.from - 1, d3s->f1mark);
1056 			if (err)
1057 				goto done;
1058 		}
1059 	}
1060 done:
1061 	free(line);
1062 	return err;
1063 }
1064 
1065 static const struct got_error *
1066 increase(struct diff3_state *d3s)
1067 {
1068 	size_t newsz, incr;
1069 	struct diff *d;
1070 	char *s;
1071 
1072 	/* are the memset(3) calls needed? */
1073 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
1074 	incr = newsz - d3s->szchanges;
1075 
1076 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
1077 	if (d == NULL)
1078 		return got_error_from_errno("reallocarray");
1079 	d3s->d13 = d;
1080 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1081 
1082 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1083 	if (d == NULL)
1084 		return got_error_from_errno("reallocarray");
1085 	d3s->d23 = d;
1086 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1087 
1088 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1089 	if (d == NULL)
1090 		return got_error_from_errno("reallocarray");
1091 	d3s->de = d;
1092 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1093 
1094 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1095 	if (s == NULL)
1096 		return got_error_from_errno("reallocarray");
1097 	d3s->overlap = s;
1098 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1099 	d3s->szchanges = newsz;
1100 
1101 	return NULL;
1102 }