xref: /freebsd/usr.bin/cmp/link.c (revision 5bf5ca772c6de2d53344a78cf461447cc322ccea)
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 <stdio.h>
36 #include <stdlib.h>
37 #include <unistd.h>
38 
39 #include "extern.h"
40 
41 void
42 c_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