1 /* $OpenBSD: ln.c,v 1.25 2019/06/28 13:34:59 deraadt Exp $ */
2 /* $NetBSD: ln.c,v 1.10 1995/03/21 09:06:10 cgd Exp $ */
3
4 /*
5 * Copyright (c) 1987, 1993, 1994
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <sys/types.h>
34 #include <sys/stat.h>
35
36 #include <err.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <libgen.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44 #include <limits.h>
45
46 int fflag; /* Unlink existing files. */
47 int hflag; /* Check new name for symlink first. */
48 int Pflag; /* Hard link to symlink. */
49 int sflag; /* Symbolic, not hard, link. */
50
51 int linkit(char *, char *, int);
52 void usage(void) __dead;
53
54 int
main(int argc,char * argv[])55 main(int argc, char *argv[])
56 {
57 struct stat sb;
58 int ch, exitval;
59 char *sourcedir;
60
61 if (pledge("stdio rpath cpath", NULL) == -1)
62 err(1, "pledge");
63
64 while ((ch = getopt(argc, argv, "fhLnPs")) != -1)
65 switch (ch) {
66 case 'f':
67 fflag = 1;
68 break;
69 case 'h':
70 case 'n':
71 hflag = 1;
72 break;
73 case 'L':
74 Pflag = 0;
75 break;
76 case 'P':
77 Pflag = 1;
78 break;
79 case 's':
80 sflag = 1;
81 break;
82 default:
83 usage();
84 }
85
86 argv += optind;
87 argc -= optind;
88
89 switch(argc) {
90 case 0:
91 usage();
92 case 1: /* ln target */
93 exit(linkit(argv[0], ".", 1));
94 case 2: /* ln target source */
95 exit(linkit(argv[0], argv[1], 0));
96 }
97 /* ln target1 target2 directory */
98 sourcedir = argv[argc - 1];
99 if (stat(sourcedir, &sb))
100 err(1, "%s", sourcedir);
101 if (!S_ISDIR(sb.st_mode))
102 usage();
103 for (exitval = 0; *argv != sourcedir; ++argv)
104 exitval |= linkit(*argv, sourcedir, 1);
105 exit(exitval);
106 }
107
108 /*
109 * Nomenclature warning!
110 *
111 * In this source "target" and "source" are used the opposite way they
112 * are used in the ln(1) manual. Here "target" is the existing file and
113 * "source" specifies the to-be-created link to "target".
114 */
115 int
linkit(char * target,char * source,int isdir)116 linkit(char *target, char *source, int isdir)
117 {
118 struct stat sb;
119 char *p, path[PATH_MAX];
120 int (*statf)(const char *, struct stat *);
121 int exists, n;
122
123 if (!sflag) {
124 /* If target doesn't exist, quit now. */
125 if ((Pflag ? lstat : stat)(target, &sb)) {
126 warn("%s", target);
127 return (1);
128 }
129 /* Only symbolic links to directories. */
130 if (S_ISDIR(sb.st_mode)) {
131 warnc(EISDIR, "%s", target);
132 return (1);
133 }
134 }
135
136 statf = hflag ? lstat : stat;
137
138 /* If the source is a directory, append the target's name. */
139 if (isdir || (!statf(source, &sb) && S_ISDIR(sb.st_mode))) {
140 if ((p = basename(target)) == NULL) {
141 warn("%s", target);
142 return (1);
143 }
144 n = snprintf(path, sizeof(path), "%s/%s", source, p);
145 if (n < 0 || n >= sizeof(path)) {
146 warnc(ENAMETOOLONG, "%s/%s", source, p);
147 return (1);
148 }
149 source = path;
150 }
151
152 exists = (lstat(source, &sb) == 0);
153 /*
154 * If doing hard links and the source (destination) exists and it
155 * actually is the same file like the target (existing file), we
156 * complain that the files are identical. If -f is specified, we
157 * accept the job as already done and return with success.
158 */
159 if (exists && !sflag) {
160 struct stat tsb;
161
162 if ((Pflag ? lstat : stat)(target, &tsb)) {
163 warn("%s: disappeared", target);
164 return (1);
165 }
166
167 if (tsb.st_dev == sb.st_dev && tsb.st_ino == sb.st_ino) {
168 if (fflag)
169 return (0);
170 else {
171 warnx("%s and %s are identical (nothing done).",
172 target, source);
173 return (1);
174 }
175 }
176 }
177 /*
178 * If the file exists, and -f was specified, unlink it.
179 * Attempt the link.
180 */
181 if ((fflag && unlink(source) == -1 && errno != ENOENT) ||
182 (sflag ? symlink(target, source) :
183 linkat(AT_FDCWD, target, AT_FDCWD, source,
184 Pflag ? 0 : AT_SYMLINK_FOLLOW))) {
185 warn("%s", source);
186 return (1);
187 }
188
189 return (0);
190 }
191
192 void
usage(void)193 usage(void)
194 {
195 extern char *__progname;
196
197 (void)fprintf(stderr,
198 "usage: %s [-fhLnPs] source [target]\n"
199 " %s [-fLPs] source ... [directory]\n",
200 __progname, __progname);
201 exit(1);
202 }
203