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("$FreeBSD$");
31
32#include <sys/types.h>
33#include <err.h>
34#include <limits.h>
35#include <stdbool.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <unistd.h>
39
40#include "extern.h"
41
42void
43c_link(const char *file1, off_t skip1, const char *file2, off_t skip2)
44{
45	char buf1[PATH_MAX], *p1;
46	char buf2[PATH_MAX], *p2;
47	int dfound, len1, len2;
48	off_t byte;
49	u_char ch;
50
51	if ((len1 = readlink(file1, buf1, sizeof(buf1) - 1)) < 0) {
52		if (!sflag)
53			err(ERR_EXIT, "%s", file1);
54		else
55			exit(ERR_EXIT);
56	}
57
58	if ((len2 = readlink(file2, buf2, sizeof(buf2) - 1)) < 0) {
59		if (!sflag)
60			err(ERR_EXIT, "%s", file2);
61		else
62			exit(ERR_EXIT);
63	}
64
65	if (skip1 > len1)
66		skip1 = len1;
67	buf1[len1] = '\0';
68
69	if (skip2 > len2)
70		skip2 = len2;
71	buf2[len2] = '\0';
72
73	dfound = 0;
74	byte = 1;
75	for (p1 = buf1 + skip1, p2 = buf2 + skip2; *p1 && *p2; p1++, p2++) {
76		if ((ch = *p1) != *p2) {
77			if (xflag) {
78				dfound = 1;
79				(void)printf("%08llx %02x %02x\n",
80				    (long long)byte - 1, ch, *p2);
81			} else if (lflag) {
82				dfound = 1;
83				(void)printf("%6lld %3o %3o\n",
84				    (long long)byte, ch, *p2);
85			} else
86				diffmsg(file1, file2, byte, 1);
87				/* NOTREACHED */
88		}
89		byte++;
90	}
91
92	if (*p1 || *p2)
93		eofmsg (*p1 ? file2 : file1);
94	if (dfound)
95		exit(DIFF_EXIT);
96}
97