xref: /freebsd/usr.bin/cmp/link.c (revision 87b759f0fa1f7554d50ce640c40138512bbded44)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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/types.h>
30 
31 #include <err.h>
32 #include <limits.h>
33 #include <stdbool.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <unistd.h>
37 
38 #include "extern.h"
39 
40 int
41 c_link(const char *file1, off_t skip1, const char *file2, off_t skip2,
42     off_t limit)
43 {
44 	char buf1[PATH_MAX], *p1;
45 	char buf2[PATH_MAX], *p2;
46 	ssize_t len1, len2;
47 	int dfound;
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;
76 	    *p1 && *p2 && (limit == 0 || byte <= limit); p1++, p2++) {
77 		if ((ch = *p1) != *p2) {
78 			if (xflag) {
79 				dfound = 1;
80 				(void)printf("%08llx %02x %02x\n",
81 				    (long long)byte - 1, ch, *p2);
82 			} else if (lflag) {
83 				dfound = 1;
84 				if (bflag)
85 					(void)printf("%6lld %3o %c %3o %c\n",
86 					    (long long)byte, ch, ch, *p2, *p2);
87 				else
88 					(void)printf("%6lld %3o %3o\n",
89 					    (long long)byte, ch, *p2);
90 			} else {
91 				diffmsg(file1, file2, byte, 1, ch, *p2);
92 				return (DIFF_EXIT);
93 			}
94 		}
95 		byte++;
96 	}
97 
98 	if (*p1 || *p2) {
99 		eofmsg (*p1 ? file2 : file1);
100 		return (DIFF_EXIT);
101 	}
102 	return (dfound ? DIFF_EXIT : 0);
103 }
104