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Date:: Mon Oct 7 10:26:33 2019 UTC
Message:: more mechanical conversions to struct got_error: buf_load() and buf_alloc()
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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 #include <sys/queue.h>
69 
70 #include <ctype.h>
71 #include <limits.h>
72 #include <stdio.h>
73 #include <stdarg.h>
74 #include <stdlib.h>
75 #include <string.h>
76 #include <time.h>
77 #include <unistd.h>
78 
79 #include "got_error.h"
80 #include "got_opentemp.h"
81 #include "got_object.h"
82 
83 #include "buf.h"
84 #include "rcsutil.h"
85 #include "got_lib_diff.h"
86 #include "worklist.h"
87 
88 #ifndef nitems
89 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
90 #endif
91 
92 /* diff3 - 3-way differential file comparison */
93 
94 /* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
95  *
96  * d13 = diff report on f1 vs f3
97  * d23 = diff report on f2 vs f3
98  * f1, f2, f3 the 3 files
99  * if changes in f1 overlap with changes in f3, m1 and m3 are used
100  * to mark the overlaps; otherwise, the file names f1 and f3 are used
101  * (only for options E and X).
102  */
103 
104 /*
105  * "from" is first in range of changed lines; "to" is last+1
106  * from=to=line after point of insertion for added lines.
107  */
108 struct range {
109 	int from;
110 	int to;
111 };
112 
113 struct diff {
114 	struct range old;
115 	struct range new;
116 };
117 
118 struct diff3_state {
119 	size_t szchanges;
120 
121 	struct diff *d13;
122 	struct diff *d23;
123 
124 	/*
125 	 * "de" is used to gather editing scripts.  These are later spewed out
126 	 * in reverse order.  Its first element must be all zero, the "new"
127 	 * component of "de" contains line positions or byte positions
128 	 * depending on when you look (!?).  Array overlap indicates which
129 	 * sections in "de" correspond to lines that are different in all
130 	 * three files.
131 	 */
132 	struct diff *de;
133 	char *overlap;
134 	int overlapcnt;
135 	FILE *fp[3];
136 	int cline[3];		/* # of the last-read line in each file (0-2) */
137 
138 	/*
139 	 * the latest known correspondence between line numbers of the 3 files
140 	 * is stored in last[1-3];
141 	 */
142 	int last[4];
143 	char f1mark[PATH_MAX], f3mark[PATH_MAX]; /* markers for -E and -X */
144 
145 	char *buf;
146 
147 	BUF *diffbuf;
148 };
149 
150 
151 static const struct got_error *duplicate(int *, struct range *, struct range *,
152     struct diff3_state *);
153 static const struct got_error *edit(struct diff *, int, int *,
154     struct diff3_state *);
155 static const struct got_error *getchange(char **, FILE *, struct diff3_state *);
156 static const struct got_error *get_line(char **, FILE *, size_t *,
157     struct diff3_state *);
158 static int number(char **);
159 static const struct got_error *readin(size_t *, char *, struct diff **,
160     struct diff3_state *);
161 static int ed_patch_lines(struct rcs_lines *, struct rcs_lines *);
162 static const struct got_error *skip(int *, int, int, char *,
163     struct diff3_state *);
164 static const struct got_error *edscript(int, struct diff3_state *);
165 static const struct got_error *merge(size_t, size_t, struct diff3_state *);
166 static const struct got_error *prange(struct range *, struct diff3_state *);
167 static const struct got_error *repos(int, struct diff3_state *);
168 static const struct got_error *increase(struct diff3_state *);
169 static const struct got_error *diff3_internal(char *, char *, char *,
170     char *, char *, const char *, const char *, struct diff3_state *,
171     const char *, const char *);
172 
173 static const struct got_error *
174 diff_output(BUF *diffbuf, const char *fmt, ...)
175 {
176 	const struct got_error *err = NULL;
177 	va_list vap;
178 	int i;
179 	char *str;
180 	size_t newsize;
181 
182 	va_start(vap, fmt);
183 	i = vasprintf(&str, fmt, vap);
184 	va_end(vap);
185 	if (i == -1)
186 		return got_error_from_errno("vasprintf");
187 	err = buf_append(&newsize, diffbuf, str, strlen(str));
188 	free(str);
189 	return err;
190 }
191 
192 static const struct got_error*
193 diffreg(BUF **d, const char *path1, const char *path2)
194 {
195 	const struct got_error *err = NULL;
196 	FILE *f1 = NULL, *f2 = NULL, *outfile = NULL;
197 	char *outpath = NULL;
198 	struct got_diff_state ds;
199 	struct got_diff_args args;
200 	int res;
201 
202 	*d = NULL;
203 
204 	f1 = fopen(path1, "r");
205 	if (f1 == NULL) {
206 		err = got_error_from_errno2("fopen", path1);
207 		goto done;
208 	}
209 	f2 = fopen(path2, "r");
210 	if (f1 == NULL) {
211 		err = got_error_from_errno2("fopen", path2);
212 		goto done;
213 	}
214 
215 	err = got_opentemp_named(&outpath, &outfile, "/tmp/got-diffreg");
216 	if (err)
217 		goto done;
218 
219 	memset(&ds, 0, sizeof(ds));
220 	/* XXX should stat buffers be passed in args instead of ds? */
221 	if (stat(path1, &ds.stb1) == -1) {
222 		err = got_error_from_errno2("stat", path1);
223 		goto done;
224 	}
225 	if (stat(path2, &ds.stb2) == -1) {
226 		err = got_error_from_errno2("stat", path2);
227 		goto done;
228 	}
229 
230 	memset(&args, 0, sizeof(args));
231 	args.diff_format = D_NORMAL;
232 	args.label[0] = "";
233 	args.label[1] = "";
234 	args.diff_context = 0;
235 
236 	err = got_diffreg(&res, f1, f2, D_FORCEASCII, &args, &ds,
237 	    outfile, NULL);
238 	if (err)
239 		goto done;
240 
241 	if (fflush(outfile) != 0) {
242 		err = got_error_from_errno2("fflush", outpath);
243 		goto done;
244 	}
245 
246 	err = buf_load(d, outpath);
247 done:
248 	if (outpath) {
249 		unlink(outpath);
250 		free(outpath);
251 	}
252 	if (outfile && fclose(outfile) != 0 && err == NULL)
253 		err = got_error_from_errno("fclose");
254 	if (f1 && fclose(f1) != 0 && err == NULL)
255 		err = got_error_from_errno("fclose");
256 	if (f2 && fclose(f2) != 0 && err == NULL)
257 		err = got_error_from_errno("fclose");
258 	return err;
259 }
260 
261 /*
262  * For merge(1).
263  */
264 const struct got_error *
265 got_merge_diff3(int *overlapcnt, int outfd, const char *p1, const char *p2,
266     const char *p3, const char *label1, const char *label3)
267 {
268 	const struct got_error *err = NULL;
269 	char *dp13, *dp23, *path1, *path2, *path3;
270 	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
271 	u_char *data, *patch;
272 	size_t dlen, plen;
273 	struct wklhead temp_files;
274 	struct diff3_state *d3s;
275 	int i;
276 
277 	*overlapcnt = 0;
278 
279 	SLIST_INIT(&temp_files);
280 
281 	d3s = calloc(1, sizeof(*d3s));
282 	if (d3s == NULL)
283 		return got_error_from_errno("calloc");
284 
285 	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
286 	dp13 = dp23 = path1 = path2 = path3 = NULL;
287 	data = patch = NULL;
288 
289 	err = buf_load(&b1, p1);
290 	if (err)
291 		goto out;
292 	err = buf_load(&b2, p2);
293 	if (err)
294 		goto out;
295 	err = buf_load(&b3, p3);
296 	if (err)
297 		goto out;
298 
299 	err = buf_alloc(&diffb, 128);
300 	if (err)
301 		goto out;
302 
303 	if (asprintf(&path1, "/tmp/got-diff1.XXXXXXXX") == -1) {
304 		err = got_error_from_errno("asprintf");
305 		goto out;
306 	}
307 	if (asprintf(&path2, "/tmp/got-diff2.XXXXXXXX") == -1) {
308 		err = got_error_from_errno("asprintf");
309 		goto out;
310 	}
311 	if (asprintf(&path3, "/tmp/got-diff3.XXXXXXXX") == -1) {
312 		err = got_error_from_errno("asprintf");
313 		goto out;
314 	}
315 
316 	err = buf_write_stmp(b1, path1, &temp_files);
317 	if (err)
318 		goto out;
319 	err = buf_write_stmp(b2, path2, &temp_files);
320 	if (err)
321 		goto out;
322 	err = buf_write_stmp(b3, path3, &temp_files);
323 	if (err)
324 		goto out;
325 
326 	buf_free(b2);
327 	b2 = NULL;
328 
329 	err = diffreg(&d1, path1, path3);
330 	if (err) {
331 		buf_free(diffb);
332 		diffb = NULL;
333 		goto out;
334 
335 	}
336 	err = diffreg(&d2, path2, path3);
337 	if (err) {
338 		buf_free(diffb);
339 		diffb = NULL;
340 		goto out;
341 	}
342 
343 	if (asprintf(&dp13, "/tmp/got-d13.XXXXXXXXXX") == -1) {
344 		err = got_error_from_errno("asprintf");
345 		goto out;
346 	}
347 	err = buf_write_stmp(d1, dp13, &temp_files);
348 	if (err)
349 		goto out;
350 
351 	buf_free(d1);
352 	d1 = NULL;
353 
354 	if (asprintf(&dp23, "/tmp/got-d23.XXXXXXXXXX") == -1) {
355 		err = got_error_from_errno("asprintf");
356 		goto out;
357 	}
358 	err = buf_write_stmp(d2, dp23, &temp_files);
359 	if (err)
360 		goto out;
361 
362 	buf_free(d2);
363 	d2 = NULL;
364 
365 	d3s->diffbuf = diffb;
366 	err = diff3_internal(dp13, dp23, path1, path2, path3,
367 	    label1, label3, d3s, label1, label3);
368 	if (err) {
369 		buf_free(diffb);
370 		diffb = NULL;
371 		goto out;
372 	}
373 
374 	plen = buf_len(diffb);
375 	patch = buf_release(diffb);
376 	dlen = buf_len(b1);
377 	data = buf_release(b1);
378 
379 	diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines);
380 out:
381 	buf_free(b2);
382 	buf_free(b3);
383 	buf_free(d1);
384 	buf_free(d2);
385 
386 	(void)unlink(path1);
387 	(void)unlink(path2);
388 	(void)unlink(path3);
389 	(void)unlink(dp13);
390 	(void)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 	worklist_clean(&temp_files, worklist_unlink);
401 
402 	for (i = 0; i < nitems(d3s->fp); i++) {
403 		if (d3s->fp[i] && fclose(d3s->fp[i]) != 0 && err == NULL)
404 			err = got_error_from_errno("fclose");
405 	}
406 	if (err == NULL && diffb) {
407 		if (buf_write_fd(diffb, outfd) < 0)
408 			err = got_error_from_errno("buf_write_fd");
409 		*overlapcnt = d3s->overlapcnt;
410 	}
411 	free(d3s);
412 	buf_free(diffb);
413 	return err;
414 }
415 
416 static const struct got_error *
417 diff3_internal(char *dp13, char *dp23, char *path1, char *path2, char *path3,
418     const char *fmark, const char *rmark, struct diff3_state *d3s,
419     const char *label1, const char *label3)
420 {
421 	const struct got_error *err = NULL;
422 	ssize_t m, n;
423 	int i;
424 
425 	i = snprintf(d3s->f1mark, sizeof(d3s->f1mark),
426 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_BEGIN, label1);
427 	if (i < 0 || i >= (int)sizeof(d3s->f1mark))
428 		return got_error(GOT_ERR_NO_SPACE);
429 
430 	i = snprintf(d3s->f3mark, sizeof(d3s->f3mark),
431 	    "%s %s", GOT_DIFF_CONFLICT_MARKER_END, label3);
432 	if (i < 0 || i >= (int)sizeof(d3s->f3mark))
433 		return got_error(GOT_ERR_NO_SPACE);
434 
435 	err = increase(d3s);
436 	if (err)
437 		return err;
438 
439 	err = readin(&m, dp13, &d3s->d13, d3s);
440 	if (err)
441 		return err;
442 	err = readin(&n, dp23, &d3s->d23, d3s);
443 	if (err)
444 		return err;
445 
446 	if ((d3s->fp[0] = fopen(path1, "r")) == NULL)
447 		return got_error_from_errno2("fopen", path1);
448 	if ((d3s->fp[1] = fopen(path2, "r")) == NULL)
449 		return got_error_from_errno2("fopen", path2);
450 	if ((d3s->fp[2] = fopen(path3, "r")) == NULL)
451 		return got_error_from_errno2("fopen", path3);
452 
453 	return merge(m, n, d3s);
454 }
455 
456 static int
457 ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
458 {
459 	char op, *ep;
460 	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
461 	int start, end, i, lineno;
462 	u_char tmp;
463 
464 	dlp = TAILQ_FIRST(&(dlines->l_lines));
465 	lp = TAILQ_FIRST(&(plines->l_lines));
466 
467 	end = 0;
468 	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
469 	    lp = TAILQ_NEXT(lp, l_list)) {
470 		/* Skip blank lines */
471 		if (lp->l_len < 2)
472 			continue;
473 
474 		/* NUL-terminate line buffer for strtol() safety. */
475 		tmp = lp->l_line[lp->l_len - 1];
476 		lp->l_line[lp->l_len - 1] = '\0';
477 
478 		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
479 		op = lp->l_line[lp->l_len - 2];
480 		start = (int)strtol(lp->l_line, &ep, 10);
481 
482 		/* Restore the last byte of the buffer */
483 		lp->l_line[lp->l_len - 1] = tmp;
484 
485 		if (op == 'a') {
486 			if (start > dlines->l_nblines ||
487 			    start < 0 || *ep != 'a')
488 				return -1;
489 		} else if (op == 'c') {
490 			if (start > dlines->l_nblines ||
491 			    start < 0 || (*ep != ',' && *ep != 'c'))
492 				return -1;
493 
494 			if (*ep == ',') {
495 				ep++;
496 				end = (int)strtol(ep, &ep, 10);
497 				if (end < 0 || *ep != 'c')
498 					return -1;
499 			} else {
500 				end = start;
501 			}
502 		}
503 
504 
505 		for (;;) {
506 			if (dlp == NULL)
507 				break;
508 			if (dlp->l_lineno == start)
509 				break;
510 			if (dlp->l_lineno > start) {
511 				dlp = TAILQ_PREV(dlp, tqh, l_list);
512 			} else if (dlp->l_lineno < start) {
513 				ndlp = TAILQ_NEXT(dlp, l_list);
514 				if (ndlp->l_lineno > start)
515 					break;
516 				dlp = ndlp;
517 			}
518 		}
519 
520 		if (dlp == NULL)
521 			return -1;
522 
523 
524 		if (op == 'c') {
525 			insert_after = TAILQ_PREV(dlp, tqh, l_list);
526 			for (i = 0; i <= (end - start); i++) {
527 				ndlp = TAILQ_NEXT(dlp, l_list);
528 				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
529 				dlp = ndlp;
530 			}
531 			dlp = insert_after;
532 		}
533 
534 		if (op == 'a' || op == 'c') {
535 			for (;;) {
536 				ndlp = lp;
537 				lp = TAILQ_NEXT(lp, l_list);
538 				if (lp == NULL)
539 					return -1;
540 
541 				if (lp->l_len == 2 &&
542 				    lp->l_line[0] == '.' &&
543 				    lp->l_line[1] == '\n')
544 					break;
545 
546 				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
547 				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
548 				    lp, l_list);
549 				dlp = lp;
550 
551 				lp->l_lineno = start;
552 				lp = ndlp;
553 			}
554 		}
555 
556 		/*
557 		 * always resort lines as the markers might be put at the
558 		 * same line as we first started editing.
559 		 */
560 		lineno = 0;
561 		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
562 			sort->l_lineno = lineno++;
563 		dlines->l_nblines = lineno - 1;
564 	}
565 
566 	return (0);
567 }
568 
569 /*
570  * Pick up the line numbers of all changes from one change file.
571  * (This puts the numbers in a vector, which is not strictly necessary,
572  * since the vector is processed in one sequential pass.
573  * The vector could be optimized out of existence)
574  */
575 static const struct got_error *
576 readin(size_t *n, char *name, struct diff **dd, struct diff3_state *d3s)
577 {
578 	const struct got_error *err = NULL;
579 	int a, b, c, d;
580 	char kind, *p;
581 	size_t i;
582 
583 	*n = 0;
584 
585 	d3s->fp[0] = fopen(name, "r");
586 	if (d3s->fp[0] == NULL)
587 		return got_error_from_errno2("fopen", name);
588 	err = getchange(&p, d3s->fp[0], d3s);
589 	if (err)
590 		return err;
591 	for (i = 0; p; i++) {
592 		if (i >= d3s->szchanges - 1) {
593 			err = increase(d3s);
594 			if (err)
595 				return err;
596 		}
597 		a = b = number(&p);
598 		if (*p == ',') {
599 			p++;
600 			b = number(&p);
601 		}
602 		kind = *p++;
603 		c = d = number(&p);
604 		if (*p == ',') {
605 			p++;
606 			d = number(&p);
607 		}
608 		if (kind == 'a')
609 			a++;
610 		if (kind == 'd')
611 			c++;
612 		b++;
613 		d++;
614 		(*dd)[i].old.from = a;
615 		(*dd)[i].old.to = b;
616 		(*dd)[i].new.from = c;
617 		(*dd)[i].new.to = d;
618 
619 		err = getchange(&p, d3s->fp[0], d3s);
620 		if (err)
621 			return err;
622 	}
623 
624 	if (i) {
625 		(*dd)[i].old.from = (*dd)[i - 1].old.to;
626 		(*dd)[i].new.from = (*dd)[i - 1].new.to;
627 	}
628 
629 	if (fclose(d3s->fp[0]) != 0)
630 		err = got_error_from_errno("fclose");
631 
632 	*n = i;
633 	return err;
634 }
635 
636 static int
637 number(char **lc)
638 {
639 	int nn;
640 
641 	nn = 0;
642 	while (isdigit((unsigned char)(**lc)))
643 		nn = nn*10 + *(*lc)++ - '0';
644 
645 	return (nn);
646 }
647 
648 static const struct got_error *
649 getchange(char **line, FILE *b, struct diff3_state *d3s)
650 {
651 	const struct got_error *err = NULL;
652 
653 	*line = NULL;
654 	do {
655 		if (*line && isdigit((unsigned char)(*line)[0]))
656 			return NULL;
657 		err = get_line(line, b, NULL, d3s);
658 		if (err)
659 			return err;
660 	} while (*line);
661 
662 	return NULL;
663 }
664 
665 static const struct got_error *
666 get_line(char **ret, FILE *b, size_t *n, struct diff3_state *d3s)
667 {
668 	const struct got_error *err = NULL;
669 	char *cp = NULL;
670 	size_t size;
671 	ssize_t len;
672 	char *new;
673 
674 	*ret = NULL;
675 
676 	len = getline(&cp, &size, b);
677 	if (len == -1) {
678 		if (ferror(b))
679 			err = got_error_from_errno("getline");
680 		goto done;
681 	}
682 
683 	if (cp[len - 1] != '\n') {
684 		len++;
685 		if (len + 1 > size) {
686 			new = realloc(cp, len + 1);
687 			if (new == NULL) {
688 				err = got_error_from_errno("realloc");
689 				goto done;
690 			}
691 			cp = new;
692 		}
693 		cp[len - 1] = '\n';
694 		cp[len] = '\0';
695 	}
696 
697 	free(d3s->buf);
698 	*ret = d3s->buf = cp;
699 	cp = NULL;
700 	if (n != NULL)
701 		*n = len;
702 done:
703 	free(cp);
704 	return err;
705 }
706 
707 static const struct got_error *
708 merge(size_t m1, size_t m2, struct diff3_state *d3s)
709 {
710 	const struct got_error *err = NULL;
711 	struct diff *d1, *d2;
712 	int dpl, j, t1, t2;
713 
714 	d1 = d3s->d13;
715 	d2 = d3s->d23;
716 	j = 0;
717 	for (;;) {
718 		t1 = (d1 < d3s->d13 + m1);
719 		t2 = (d2 < d3s->d23 + m2);
720 		if (!t1 && !t2)
721 			break;
722 
723 		/* first file is different from others */
724 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
725 			/* stuff peculiar to 1st file */
726 			d1++;
727 			continue;
728 		}
729 
730 		/* second file is different from others */
731 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
732 			d2++;
733 			continue;
734 		}
735 
736 		/*
737 		 * Merge overlapping changes in first file
738 		 * this happens after extension (see below).
739 		 */
740 		if (d1 + 1 < d3s->d13 + m1 && d1->new.to >= d1[1].new.from) {
741 			d1[1].old.from = d1->old.from;
742 			d1[1].new.from = d1->new.from;
743 			d1++;
744 			continue;
745 		}
746 
747 		/* merge overlapping changes in second */
748 		if (d2 + 1 < d3s->d23 + m2 && d2->new.to >= d2[1].new.from) {
749 			d2[1].old.from = d2->old.from;
750 			d2[1].new.from = d2->new.from;
751 			d2++;
752 			continue;
753 		}
754 		/* stuff peculiar to third file or different in all */
755 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
756 			err = duplicate(&dpl, &d1->old, &d2->old, d3s);
757 			if (err)
758 				return err;
759 
760 			/*
761 			 * dpl = 0 means all files differ
762 			 * dpl = 1 means files 1 and 2 identical
763 			 */
764 			err = edit(d1, dpl, &j, d3s);
765 			if (err)
766 				return err;
767 			d1++;
768 			d2++;
769 			continue;
770 		}
771 
772 		/*
773 		 * Overlapping changes from file 1 and 2; extend changes
774 		 * appropriately to make them coincide.
775 		 */
776 		if (d1->new.from < d2->new.from) {
777 			d2->old.from -= d2->new.from - d1->new.from;
778 			d2->new.from = d1->new.from;
779 		} else if (d2->new.from < d1->new.from) {
780 			d1->old.from -= d1->new.from - d2->new.from;
781 			d1->new.from = d2->new.from;
782 		}
783 		if (d1->new.to > d2->new.to) {
784 			d2->old.to += d1->new.to - d2->new.to;
785 			d2->new.to = d1->new.to;
786 		} else if (d2->new.to > d1->new.to) {
787 			d1->old.to += d2->new.to - d1->new.to;
788 			d1->new.to = d2->new.to;
789 		}
790 	}
791 
792 	return (edscript(j, d3s));
793 }
794 
795 /*
796  * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
797  */
798 static const struct got_error *
799 prange(struct range *rold, struct diff3_state *d3s)
800 {
801 	const struct got_error *err = NULL;
802 
803 	if (rold->to <= rold->from) {
804 		err = diff_output(d3s->diffbuf, "%da\n", rold->from - 1);
805 		if (err)
806 			return err;
807 	} else {
808 		err = diff_output(d3s->diffbuf, "%d", rold->from);
809 		if (err)
810 			return err;
811 		if (rold->to > rold->from + 1) {
812 			err = diff_output(d3s->diffbuf, ",%d", rold->to - 1);
813 			if (err)
814 				return err;
815 		}
816 		err = diff_output(d3s->diffbuf, "c\n");
817 		if (err)
818 			return err;
819 	}
820 
821 	return NULL;
822 }
823 
824 /*
825  * skip to just before line number from in file "i".  If "pr" is non-NULL,
826  * print all skipped stuff with string pr as a prefix.
827  */
828 static const struct got_error *
829 skip(int *nskipped, int i, int from, char *pr, struct diff3_state *d3s)
830 {
831 	const struct got_error *err = NULL;
832 	size_t j, n;
833 	char *line;
834 
835 	*nskipped = 0;
836 	for (n = 0; d3s->cline[i] < from - 1; n += j) {
837 		err = get_line(&line, d3s->fp[i], &j, d3s);
838 		if (err)
839 			return err;
840 		if (pr != NULL) {
841 			err = diff_output(d3s->diffbuf, "%s%s", pr, line);
842 			if (err)
843 				return err;
844 		}
845 		d3s->cline[i]++;
846 	}
847 	*nskipped = n;
848 	return NULL;
849 }
850 
851 /*
852  * Set *dpl to 1 or 0 according as the old range (in file 1) contains exactly
853  * the same data as the new range (in file 2).
854  */
855 static const struct got_error *
856 duplicate(int *dpl, struct range *r1, struct range *r2, struct diff3_state *d3s)
857 {
858 	const struct got_error *err = NULL;
859 	int c,d;
860 	int nchar;
861 	int nline, nskipped;
862 
863 	*dpl = 0;
864 
865 	if (r1->to - r1->from != r2->to - r2->from)
866 		return NULL;
867 
868 	err = skip(&nskipped, 0, r1->from, NULL, d3s);
869 	if (err)
870 		return err;
871 	err = skip(&nskipped, 1, r2->from, NULL, d3s);
872 	if (err)
873 		return err;
874 	nchar = 0;
875 	for (nline = 0; nline < r1->to - r1->from; nline++) {
876 		do {
877 			c = getc(d3s->fp[0]);
878 			if (c == EOF)
879 				return got_ferror(d3s->fp[0], GOT_ERR_EOF);
880 			d = getc(d3s->fp[1]);
881 			if (d == EOF)
882 				return got_ferror(d3s->fp[1], GOT_ERR_EOF);
883 			nchar++;
884 			if (c != d)
885 				return repos(nchar, d3s);
886 		} while (c != '\n');
887 	}
888 	err = repos(nchar, d3s);
889 	if (err)
890 		return err;
891 	*dpl = 1;
892 	return NULL;
893 }
894 
895 static const struct got_error *
896 repos(int nchar, struct diff3_state *d3s)
897 {
898 	int i;
899 
900 	for (i = 0; i < 2; i++) {
901 		if (fseek(d3s->fp[i], (long)-nchar, SEEK_CUR) == -1)
902 			return got_ferror(d3s->fp[i], GOT_ERR_IO);
903 	}
904 
905 	return NULL;
906 }
907 
908 /*
909  * collect an editing script for later regurgitation
910  */
911 static const struct got_error *
912 edit(struct diff *diff, int fdup, int *j, struct diff3_state *d3s)
913 {
914 	const struct got_error *err = NULL;
915 	int nskipped;
916 
917 	if (((fdup + 1) & 3) == 0)
918 		return NULL;
919 	(*j)++;
920 	d3s->overlap[*j] = !fdup;
921 	if (!fdup)
922 		d3s->overlapcnt++;
923 	d3s->de[*j].old.from = diff->old.from;
924 	d3s->de[*j].old.to = diff->old.to;
925 	err = skip(&nskipped, 2, diff->new.from, NULL, d3s);
926 	if (err)
927 		return err;
928 	d3s->de[*j].new.from = d3s->de[*j - 1].new.to + nskipped;
929 	err = skip(&nskipped, 2, diff->new.to, NULL, d3s);
930 	d3s->de[*j].new.to = d3s->de[*j].new.from + nskipped;
931 	return NULL;
932 }
933 
934 /* regurgitate */
935 static const struct got_error *
936 edscript(int n, struct diff3_state *d3s)
937 {
938 	const struct got_error *err = NULL;
939 	int j, k;
940 	char block[BUFSIZ+1];
941 
942 	for (; n > 0; n--) {
943 		if (!d3s->overlap[n]) {
944 			err = prange(&d3s->de[n].old, d3s);
945 			if (err)
946 				return err;
947 		} else {
948 			err = diff_output(d3s->diffbuf, "%da\n%s\n",
949 			    d3s->de[n].old.to -1, GOT_DIFF_CONFLICT_MARKER_SEP);
950 			if (err)
951 				return err;
952 		}
953 		if (fseek(d3s->fp[2], (long)d3s->de[n].new.from, SEEK_SET)
954 		    == -1)
955 			return got_error_from_errno("fseek");
956 		k = d3s->de[n].new.to - d3s->de[n].new.from;
957 		for (; k > 0; k -= j) {
958 			j = k > BUFSIZ ? BUFSIZ : k;
959 			if (fread(block, 1, j, d3s->fp[2]) != (size_t)j)
960 				return got_ferror(d3s->fp[2], GOT_ERR_IO);
961 			block[j] = '\0';
962 			err = diff_output(d3s->diffbuf, "%s", block);
963 			if (err)
964 				return err;
965 		}
966 
967 		if (!d3s->overlap[n]) {
968 			err = diff_output(d3s->diffbuf, ".\n");
969 			if (err)
970 				return err;
971 		} else {
972 			err = diff_output(d3s->diffbuf, "%s\n.\n", d3s->f3mark);
973 			if (err)
974 				return err;
975 			err = diff_output(d3s->diffbuf, "%da\n%s\n.\n",
976 			    d3s->de[n].old.from - 1, d3s->f1mark);
977 			if (err)
978 				return err;
979 		}
980 	}
981 
982 	return NULL;
983 }
984 
985 static const struct got_error *
986 increase(struct diff3_state *d3s)
987 {
988 	size_t newsz, incr;
989 	struct diff *d;
990 	char *s;
991 
992 	/* are the memset(3) calls needed? */
993 	newsz = d3s->szchanges == 0 ? 64 : 2 * d3s->szchanges;
994 	incr = newsz - d3s->szchanges;
995 
996 	d = reallocarray(d3s->d13, newsz, sizeof(*d3s->d13));
997 	if (d == NULL)
998 		return got_error_from_errno("reallocarray");
999 	d3s->d13 = d;
1000 	memset(d3s->d13 + d3s->szchanges, 0, incr * sizeof(*d3s->d13));
1001 
1002 	d = reallocarray(d3s->d23, newsz, sizeof(*d3s->d23));
1003 	if (d == NULL)
1004 		return got_error_from_errno("reallocarray");
1005 	d3s->d23 = d;
1006 	memset(d3s->d23 + d3s->szchanges, 0, incr * sizeof(*d3s->d23));
1007 
1008 	d = reallocarray(d3s->de, newsz, sizeof(*d3s->de));
1009 	if (d == NULL)
1010 		return got_error_from_errno("reallocarray");
1011 	d3s->de = d;
1012 	memset(d3s->de + d3s->szchanges, 0, incr * sizeof(*d3s->de));
1013 
1014 	s = reallocarray(d3s->overlap, newsz, sizeof(*d3s->overlap));
1015 	if (s == NULL)
1016 		return got_error_from_errno("reallocarray");
1017 	d3s->overlap = s;
1018 	memset(d3s->overlap + d3s->szchanges, 0, incr * sizeof(*d3s->overlap));
1019 	d3s->szchanges = newsz;
1020 
1021 	return NULL;
1022 }