xref: /freebsd/usr.bin/diff3/diff3.c (revision 389e4940069316fe667ffa263fa7d6390d0a960f)
1 /*	$OpenBSD: diff3prog.c,v 1.11 2009/10/27 23:59:37 deraadt 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 #if 0
68 #ifndef lint
69 static char sccsid[] = "@(#)diff3.c	8.1 (Berkeley) 6/6/93";
70 #endif
71 #endif /* not lint */
72 #include <sys/cdefs.h>
73 __FBSDID("$FreeBSD$");
74 
75 #include <sys/capsicum.h>
76 #include <sys/procdesc.h>
77 #include <sys/types.h>
78 #include <sys/event.h>
79 #include <sys/wait.h>
80 
81 #include <capsicum_helpers.h>
82 #include <ctype.h>
83 #include <err.h>
84 #include <getopt.h>
85 #include <stdio.h>
86 #include <stdlib.h>
87 #include <string.h>
88 #include <unistd.h>
89 
90 
91 /*
92  * "from" is first in range of changed lines; "to" is last+1
93  * from=to=line after point of insertion for added lines.
94  */
95 struct range {
96 	int from;
97 	int to;
98 };
99 
100 struct diff {
101 	struct range old;
102 	struct range new;
103 };
104 
105 static size_t szchanges;
106 
107 static struct diff *d13;
108 static struct diff *d23;
109 /*
110  * "de" is used to gather editing scripts.  These are later spewed out in
111  * reverse order.  Its first element must be all zero, the "new" component
112  * of "de" contains line positions or byte positions depending on when you
113  * look (!?).  Array overlap indicates which sections in "de" correspond to
114  * lines that are different in all three files.
115  */
116 static struct diff *de;
117 static char *overlap;
118 static int  overlapcnt;
119 static FILE *fp[3];
120 static int cline[3];		/* # of the last-read line in each file (0-2) */
121 /*
122  * The latest known correspondence between line numbers of the 3 files
123  * is stored in last[1-3];
124  */
125 static int last[4];
126 static int Aflag, eflag, iflag, mflag, Tflag;
127 static int oflag;		/* indicates whether to mark overlaps (-E or -X)*/
128 static int strip_cr;
129 static char *f1mark, *f2mark, *f3mark;
130 
131 static bool duplicate(struct range *, struct range *);
132 static int edit(struct diff *, bool, int);
133 static char *getchange(FILE *);
134 static char *get_line(FILE *, size_t *);
135 static int number(char **);
136 static int readin(int fd, struct diff **);
137 static int skip(int, int, const char *);
138 static void change(int, struct range *, bool);
139 static void keep(int, struct range *);
140 static void merge(int, int);
141 static void prange(struct range *);
142 static void repos(int);
143 static void edscript(int) __dead2;
144 static void increase(void);
145 static void usage(void) __dead2;
146 
147 enum {
148 	DIFFPROG_OPT,
149 	STRIPCR_OPT,
150 };
151 
152 #define DIFF_PATH "/usr/bin/diff"
153 
154 #define OPTIONS "3aAeEiL:mTxX"
155 static struct option longopts[] = {
156 	{ "ed",			no_argument,		NULL,	'e' },
157 	{ "show-overlap",	no_argument,		NULL,	'E' },
158 	{ "overlap-only",	no_argument,		NULL,	'x' },
159 	{ "initial-tab",	no_argument,		NULL,	'T' },
160 	{ "text",		no_argument,		NULL,	'a' },
161 	{ "strip-trailing-cr",	no_argument,		NULL,	STRIPCR_OPT },
162 	{ "show-all",		no_argument,		NULL,	'A' },
163 	{ "easy-only",		no_argument,		NULL,	'3' },
164 	{ "merge",		no_argument,		NULL,	'm' },
165 	{ "label",		required_argument,	NULL,	'L' },
166 	{ "diff-program",	required_argument,	NULL,	DIFFPROG_OPT },
167 };
168 
169 static void
170 usage(void)
171 {
172 	fprintf(stderr, "usage: diff3 [-3aAeEimTxX] [-L lable1] [-L label2] "
173 	    "[ -L label3] file1 file2 file3\n");
174 	exit (2);
175 }
176 
177 static int
178 readin(int fd, struct diff **dd)
179 {
180 	int a, b, c, d;
181 	size_t i;
182 	char kind, *p;
183 	FILE *f;
184 
185 	f = fdopen(fd, "r");
186 	if (f == NULL)
187 		err(2, "fdopen");
188 	for (i=0; (p = getchange(f)); i++) {
189 		if (i >= szchanges - 1)
190 			increase();
191 		a = b = number(&p);
192 		if (*p == ',') {
193 			p++;
194 			b = number(&p);
195 		}
196 		kind = *p++;
197 		c = d = number(&p);
198 		if (*p==',') {
199 			p++;
200 			d = number(&p);
201 		}
202 		if (kind == 'a')
203 			a++;
204 		if (kind == 'd')
205 			c++;
206 		b++;
207 		d++;
208 		(*dd)[i].old.from = a;
209 		(*dd)[i].old.to = b;
210 		(*dd)[i].new.from = c;
211 		(*dd)[i].new.to = d;
212 	}
213 	if (i) {
214 		(*dd)[i].old.from = (*dd)[i-1].old.to;
215 		(*dd)[i].new.from = (*dd)[i-1].new.to;
216 	}
217 	fclose(f);
218 	return (i);
219 }
220 
221 static int
222 diffexec(const char *diffprog, char **diffargv, int fd[])
223 {
224 	int pid, pd;
225 
226 	switch (pid = pdfork(&pd, PD_CLOEXEC)) {
227 	case 0:
228 		close(fd[0]);
229 		if (dup2(fd[1], STDOUT_FILENO) == -1)
230 			err(2, "child could not duplicate descriptor");
231 		close(fd[1]);
232 		execvp(diffprog, diffargv);
233 		err(2, "could not execute diff: %s", diffprog);
234 		break;
235 	case -1:
236 		err(2, "could not fork");
237 		break;
238 	}
239 	close(fd[1]);
240 	return (pd);
241 }
242 
243 static int
244 number(char **lc)
245 {
246 	int nn;
247 
248 	nn = 0;
249 	while (isdigit((unsigned char)(**lc)))
250 		nn = nn*10 + *(*lc)++ - '0';
251 	return (nn);
252 }
253 
254 static char *
255 getchange(FILE *b)
256 {
257 	char *line;
258 
259 	while ((line = get_line(b, NULL))) {
260 		if (isdigit((unsigned char)line[0]))
261 			return (line);
262 	}
263 	return (NULL);
264 }
265 
266 
267 static char *
268 get_line(FILE *b, size_t *n)
269 {
270 	char *cp;
271 	size_t len;
272 	static char *buf;
273 	static size_t bufsize;
274 
275 	if ((cp = fgetln(b, &len)) == NULL)
276 		return (NULL);
277 
278 	if (cp[len - 1] != '\n')
279 		len++;
280 	if (len + 1 > bufsize) {
281 		do {
282 			bufsize += 1024;
283 		} while (len + 1 > bufsize);
284 		if ((buf = realloc(buf, bufsize)) == NULL)
285 			err(EXIT_FAILURE, NULL);
286 	}
287 	memcpy(buf, cp, len - 1);
288 	buf[len - 1] = '\n';
289 	buf[len] = '\0';
290 	if (n != NULL)
291 		*n = len;
292 	return (buf);
293 }
294 
295 static void
296 merge(int m1, int m2)
297 {
298 	struct diff *d1, *d2, *d3;
299 	int j, t1, t2;
300 	bool dup = false;
301 
302 	d1 = d13;
303 	d2 = d23;
304 	j = 0;
305 
306 	while ((t1 = d1 < d13 + m1) | (t2 = d2 < d23 + m2)) {
307 		/* first file is different from the others */
308 		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
309 			/* stuff peculiar to 1st file */
310 			if (eflag == 0) {
311 				printf("====1\n");
312 				change(1, &d1->old, false);
313 				keep(2, &d1->new);
314 				change(3, &d1->new, false);
315 			}
316 			d1++;
317 			continue;
318 		}
319 		/* second file is different from others */
320 		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
321 			if (eflag == 0) {
322 				printf("====2\n");
323 				keep(1, &d2->new);
324 				change(3, &d2->new, false);
325 				change(2, &d2->old, false);
326 			}
327 			d2++;
328 			continue;
329 		}
330 		/*
331 		 * Merge overlapping changes in first file
332 		 * this happens after extension (see below).
333 		 */
334 		if (d1 + 1 < d13 + m1 && d1->new.to >= d1[1].new.from) {
335 			d1[1].old.from = d1->old.from;
336 			d1[1].new.from = d1->new.from;
337 			d1++;
338 			continue;
339 		}
340 
341 		/* merge overlapping changes in second */
342 		if (d2 + 1 < d23 + m2 && d2->new.to >= d2[1].new.from) {
343 			d2[1].old.from = d2->old.from;
344 			d2[1].new.from = d2->new.from;
345 			d2++;
346 			continue;
347 		}
348 		/* stuff peculiar to third file or different in all */
349 		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
350 			dup = duplicate(&d1->old, &d2->old);
351 			/*
352 			 * dup = 0 means all files differ
353 			 * dup = 1 means files 1 and 2 identical
354 			 */
355 			if (eflag == 0) {
356 				printf("====%s\n", dup ? "3" : "");
357 				change(1, &d1->old, dup);
358 				change(2, &d2->old, false);
359 				d3 = d1->old.to > d1->old.from ? d1 : d2;
360 				change(3, &d3->new, false);
361 			} else
362 				j = edit(d1, dup, j);
363 			d1++;
364 			d2++;
365 			continue;
366 		}
367 		/*
368 		 * Overlapping changes from file 1 and 2; extend changes
369 		 * appropriately to make them coincide.
370 		 */
371 		if (d1->new.from < d2->new.from) {
372 			d2->old.from -= d2->new.from - d1->new.from;
373 			d2->new.from = d1->new.from;
374 		} else if (d2->new.from < d1->new.from) {
375 			d1->old.from -= d1->new.from - d2->new.from;
376 			d1->new.from = d2->new.from;
377 		}
378 		if (d1->new.to > d2->new.to) {
379 			d2->old.to += d1->new.to - d2->new.to;
380 			d2->new.to = d1->new.to;
381 		} else if (d2->new.to > d1->new.to) {
382 			d1->old.to += d2->new.to - d1->new.to;
383 			d1->new.to = d2->new.to;
384 		}
385 	}
386 	if (eflag)
387 		edscript(j);
388 }
389 
390 /*
391  * The range of lines rold.from thru rold.to in file i is to be changed.
392  * It is to be printed only if it does not duplicate something to be
393  * printed later.
394  */
395 static void
396 change(int i, struct range *rold, bool dup)
397 {
398 
399 	printf("%d:", i);
400 	last[i] = rold->to;
401 	prange(rold);
402 	if (dup)
403 		return;
404 	i--;
405 	skip(i, rold->from, NULL);
406 	skip(i, rold->to, "  ");
407 }
408 
409 /*
410  * Print the range of line numbers, rold.from thru rold.to, as n1,n2 or
411  * n1.
412  */
413 static void
414 prange(struct range *rold)
415 {
416 
417 	if (rold->to <= rold->from)
418 		printf("%da\n", rold->from - 1);
419 	else {
420 		printf("%d", rold->from);
421 		if (rold->to > rold->from+1)
422 			printf(",%d", rold->to - 1);
423 		printf("c\n");
424 	}
425 }
426 
427 /*
428  * No difference was reported by diff between file 1 (or 2) and file 3,
429  * and an artificial dummy difference (trange) must be ginned up to
430  * correspond to the change reported in the other file.
431  */
432 static void
433 keep(int i, struct range *rnew)
434 {
435 	int delta;
436 	struct range trange;
437 
438 	delta = last[3] - last[i];
439 	trange.from = rnew->from - delta;
440 	trange.to = rnew->to - delta;
441 	change(i, &trange, true);
442 }
443 
444 /*
445  * skip to just before line number from in file "i".  If "pr" is non-NULL,
446  * print all skipped stuff with string pr as a prefix.
447  */
448 static int
449 skip(int i, int from, const char *pr)
450 {
451 	size_t j, n;
452 	char *line;
453 
454 	for (n = 0; cline[i] < from - 1; n += j) {
455 		if ((line = get_line(fp[i], &j)) == NULL)
456 			errx(EXIT_FAILURE, "logic error");
457 		if (pr != NULL)
458 			printf("%s%s", Tflag == 1? "\t" : pr, line);
459 		cline[i]++;
460 	}
461 	return ((int) n);
462 }
463 
464 /*
465  * Return 1 or 0 according as the old range (in file 1) contains exactly
466  * the same data as the new range (in file 2).
467  */
468 static bool
469 duplicate(struct range *r1, struct range *r2)
470 {
471 	int c, d;
472 	int nchar;
473 	int nline;
474 
475 	if (r1->to-r1->from != r2->to-r2->from)
476 		return (0);
477 	skip(0, r1->from, NULL);
478 	skip(1, r2->from, NULL);
479 	nchar = 0;
480 	for (nline=0; nline < r1->to - r1->from; nline++) {
481 		do {
482 			c = getc(fp[0]);
483 			d = getc(fp[1]);
484 			if (c == -1 || d== -1)
485 				errx(EXIT_FAILURE, "logic error");
486 			nchar++;
487 			if (c != d) {
488 				repos(nchar);
489 				return (0);
490 			}
491 		} while (c != '\n');
492 	}
493 	repos(nchar);
494 	return (1);
495 }
496 
497 static void
498 repos(int nchar)
499 {
500 	int i;
501 
502 	for (i = 0; i < 2; i++)
503 		(void)fseek(fp[i], (long)-nchar, SEEK_CUR);
504 }
505 /*
506  * collect an editing script for later regurgitation
507  */
508 static int
509 edit(struct diff *diff, bool dup, int j)
510 {
511 
512 	if (((dup + 1) & eflag) == 0)
513 		return (j);
514 	j++;
515 	overlap[j] = !dup;
516 	if (!dup)
517 		overlapcnt++;
518 	de[j].old.from = diff->old.from;
519 	de[j].old.to = diff->old.to;
520 	de[j].new.from = de[j-1].new.to + skip(2, diff->new.from, NULL);
521 	de[j].new.to = de[j].new.from + skip(2, diff->new.to, NULL);
522 	return (j);
523 }
524 
525 /* regurgitate */
526 static void
527 edscript(int n)
528 {
529 	int k;
530 	size_t j;
531 	char block[BUFSIZ];
532 
533 	for (; n > 0; n--) {
534 		if (!oflag || !overlap[n]) {
535 			prange(&de[n].old);
536 		} else {
537 			printf("%da\n", de[n].old.to -1);
538 			if (Aflag) {
539 				printf("%s\n", f2mark);
540 				fseek(fp[1], de[n].old.from, SEEK_SET);
541 				for (k = de[n].old.to - de[n].old.from; k > 0; k -= j) {
542 					j = k > BUFSIZ ? BUFSIZ : k;
543 					if (fread(block, 1, j, fp[1]) != j)
544 						errx(2, "logic error");
545 					fwrite(block, 1, j, stdout);
546 				}
547 				printf("\n");
548 			}
549 			printf("=======\n");
550 		}
551 		fseek(fp[2], (long)de[n].new.from, SEEK_SET);
552 		for (k = de[n].new.to - de[n].new.from; k > 0; k-= j) {
553 			j = k > BUFSIZ ? BUFSIZ : k;
554 			if (fread(block, 1, j, fp[2]) != j)
555 				errx(2, "logic error");
556 			fwrite(block, 1, j, stdout);
557 		}
558 		if (!oflag || !overlap[n])
559 			printf(".\n");
560 		else {
561 			printf("%s\n.\n", f3mark);
562 			printf("%da\n%s\n.\n", de[n].old.from - 1, f1mark);
563 		}
564 	}
565 	if (iflag)
566 		printf("w\nq\n");
567 
568 	exit(eflag == 0 ? overlapcnt : 0);
569 }
570 
571 static void
572 increase(void)
573 {
574 	struct diff *p;
575 	char *q;
576 	size_t newsz, incr;
577 
578 	/* are the memset(3) calls needed? */
579 	newsz = szchanges == 0 ? 64 : 2 * szchanges;
580 	incr = newsz - szchanges;
581 
582 	p = realloc(d13, newsz * sizeof(struct diff));
583 	if (p == NULL)
584 		err(1, NULL);
585 	memset(p + szchanges, 0, incr * sizeof(struct diff));
586 	d13 = p;
587 	p = realloc(d23, newsz * sizeof(struct diff));
588 	if (p == NULL)
589 		err(1, NULL);
590 	memset(p + szchanges, 0, incr * sizeof(struct diff));
591 	d23 = p;
592 	p = realloc(de, newsz * sizeof(struct diff));
593 	if (p == NULL)
594 		err(1, NULL);
595 	memset(p + szchanges, 0, incr * sizeof(struct diff));
596 	de = p;
597 	q = realloc(overlap, newsz * sizeof(char));
598 	if (q == NULL)
599 		err(1, NULL);
600 	memset(q + szchanges, 0, incr * sizeof(char));
601 	overlap = q;
602 	szchanges = newsz;
603 }
604 
605 
606 int
607 main(int argc, char **argv)
608 {
609 	int ch, nblabels, status, m, n, kq, nke, nleft, i;
610 	char *labels[] = { NULL, NULL, NULL };
611 	const char *diffprog = DIFF_PATH;
612 	char *file1, *file2, *file3;
613 	char *diffargv[6];
614 	int diffargc = 0;
615 	int fd13[2], fd23[2];
616 	int pd13, pd23;
617 	cap_rights_t rights_ro;
618 	struct kevent *e;
619 
620 	nblabels = 0;
621 	eflag = 0;
622 	oflag = 0;
623 	diffargv[diffargc++] = __DECONST(char *, diffprog);
624 	while ((ch = getopt_long(argc, argv, OPTIONS, longopts, NULL)) != -1) {
625 		switch (ch) {
626 		case '3':
627 			eflag = 2;
628 			break;
629 		case 'a':
630 			diffargv[diffargc++] = __DECONST(char *, "-a");
631 			break;
632 		case 'A':
633 			Aflag = 1;
634 			break;
635 		case 'e':
636 			eflag = 3;
637 			break;
638 		case 'E':
639 			eflag = 3;
640 			oflag = 1;
641 			break;
642 		case 'i':
643 			iflag = 1;
644 			break;
645 		case 'L':
646 			oflag = 1;
647 			if (nblabels >= 3)
648 				errx(2, "too many file label options");
649 			labels[nblabels++] = optarg;
650 			break;
651 		case 'm':
652 			Aflag = 1;
653 			oflag = 1;
654 			mflag = 1;
655 			break;
656 		case 'T':
657 			Tflag = 1;
658 			break;
659 		case 'x':
660 			eflag = 1;
661 			break;
662 		case 'X':
663 			oflag = 1;
664 			eflag = 1;
665 			break;
666 		case DIFFPROG_OPT:
667 			diffprog = optarg;
668 			break;
669 		case STRIPCR_OPT:
670 			strip_cr = 1;
671 			break;
672 		}
673 	}
674 	argc -= optind;
675 	argv += optind;
676 
677 	if (Aflag) {
678 		eflag = 3;
679 		oflag = 1;
680 	}
681 
682 	if (argc != 3)
683 		usage();
684 
685 	if (caph_limit_stdio() == -1)
686 		err(2, "unable to limit stdio");
687 
688 	cap_rights_init(&rights_ro, CAP_READ, CAP_FSTAT, CAP_SEEK);
689 
690 	kq = kqueue();
691 	if (kq == -1)
692 		err(2, "kqueue");
693 
694 	e = malloc(2 * sizeof(struct kevent));
695 	if (e == NULL)
696 		err(2, "malloc");
697 
698 	/* TODO stdio */
699 	file1 = argv[0];
700 	file2 = argv[1];
701 	file3 = argv[2];
702 
703 	if (oflag) {
704 		asprintf(&f1mark, "<<<<<<< %s",
705 		    labels[0] != NULL ? labels[0] : file1);
706 		if (f1mark == NULL)
707 			err(2, "asprintf");
708 		asprintf(&f2mark, "||||||| %s",
709 		    labels[1] != NULL ? labels[1] : file2);
710 		if (f2mark == NULL)
711 			err(2, "asprintf");
712 		asprintf(&f3mark, ">>>>>>> %s",
713 		    labels[2] != NULL ? labels[2] : file3);
714 		if (f3mark == NULL)
715 			err(2, "asprintf");
716 	}
717 	fp[0] = fopen(file1, "r");
718 	if (fp[0] == NULL)
719 		err(2, "Can't open %s", file1);
720 	if (cap_rights_limit(fileno(fp[0]), &rights_ro) < 0)
721 		err(2, "unable to limit rights on: %s", file1);
722 
723 	fp[1] = fopen(file2, "r");
724 	if (fp[1] == NULL)
725 		err(2, "Can't open %s", file2);
726 	if (cap_rights_limit(fileno(fp[1]), &rights_ro) < 0)
727 		err(2, "unable to limit rights on: %s", file2);
728 
729 	fp[2] = fopen(file3, "r");
730 	if (fp[2] == NULL)
731 		err(2, "Can't open %s", file3);
732 	if (cap_rights_limit(fileno(fp[2]), &rights_ro) < 0)
733 		err(2, "unable to limit rights on: %s", file3);
734 
735 	if (pipe(fd13))
736 		err(2, "pipe");
737 	if (pipe(fd23))
738 		err(2, "pipe");
739 
740 	diffargv[diffargc] = file1;
741 	diffargv[diffargc + 1] = file3;
742 	diffargv[diffargc + 2] = NULL;
743 
744 	nleft = 0;
745 	pd13 = diffexec(diffprog, diffargv, fd13);
746 	EV_SET(e + nleft , pd13, EVFILT_PROCDESC, EV_ADD, NOTE_EXIT, 0, NULL);
747 	if (kevent(kq, e + nleft, 1, NULL, 0, NULL) == -1)
748 		err(2, "kevent1");
749 	nleft++;
750 
751 	diffargv[diffargc] = file2;
752 	pd23 = diffexec(diffprog, diffargv, fd23);
753 	EV_SET(e + nleft , pd23, EVFILT_PROCDESC, EV_ADD, NOTE_EXIT, 0, NULL);
754 	if (kevent(kq, e + nleft, 1, NULL, 0, NULL) == -1)
755 		err(2, "kevent2");
756 	nleft++;
757 
758 	caph_cache_catpages();
759 	if (cap_enter() < 0 && errno != ENOSYS)
760 		err(2, "unable to enter capability mode");
761 
762 	/* parse diffs */
763 	increase();
764 	m = readin(fd13[0], &d13);
765 	n = readin(fd23[0], &d23);
766 
767 	/* waitpid cooked over pdforks */
768 	while (nleft > 0) {
769 		nke = kevent(kq, NULL, 0, e, nleft, NULL);
770 		if (nke == -1)
771 			err(2, "kevent");
772 		for (i = 0; i < nke; i++) {
773 			status = e[i].data;
774 			if (WIFEXITED(status) && WEXITSTATUS(status) >= 2)
775 				errx(2, "diff exited abormally");
776 			else if (WIFSIGNALED(status))
777 				errx(2, "diff killed by signal %d",
778 				    WTERMSIG(status));
779 		}
780 		nleft -= nke;
781 	}
782 	merge(m, n);
783 
784 	return (EXIT_SUCCESS);
785 }
786