1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2005 Brian Somers <brian@FreeBSD.org>
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 must retain the above copyright
11 *    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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: stable/11/usr.bin/cmp/link.c 330449 2018-03-05 07:26:05Z eadler $");
31
32#include <sys/types.h>
33#include <err.h>
34#include <limits.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <unistd.h>
38
39#include "extern.h"
40
41void
42c_link(const char *file1, off_t skip1, const char *file2, off_t skip2)
43{
44	char buf1[PATH_MAX], *p1;
45	char buf2[PATH_MAX], *p2;
46	int dfound, len1, len2;
47	off_t byte;
48	u_char ch;
49
50	if ((len1 = readlink(file1, buf1, sizeof(buf1) - 1)) < 0) {
51		if (!sflag)
52			err(ERR_EXIT, "%s", file1);
53		else
54			exit(ERR_EXIT);
55	}
56
57	if ((len2 = readlink(file2, buf2, sizeof(buf2) - 1)) < 0) {
58		if (!sflag)
59			err(ERR_EXIT, "%s", file2);
60		else
61			exit(ERR_EXIT);
62	}
63
64	if (skip1 > len1)
65		skip1 = len1;
66	buf1[len1] = '\0';
67
68	if (skip2 > len2)
69		skip2 = len2;
70	buf2[len2] = '\0';
71
72	dfound = 0;
73	byte = 1;
74	for (p1 = buf1 + skip1, p2 = buf2 + skip2; *p1 && *p2; p1++, p2++) {
75		if ((ch = *p1) != *p2) {
76			if (xflag) {
77				dfound = 1;
78				(void)printf("%08llx %02x %02x\n",
79				    (long long)byte - 1, ch, *p2);
80			} else if (lflag) {
81				dfound = 1;
82				(void)printf("%6lld %3o %3o\n",
83				    (long long)byte, ch, *p2);
84			} else
85				diffmsg(file1, file2, byte, 1);
86				/* NOTREACHED */
87		}
88		byte++;
89	}
90
91	if (*p1 || *p2)
92		eofmsg (*p1 ? file2 : file1);
93	if (dfound)
94		exit(DIFF_EXIT);
95}
96