Always warn about identical target and source. Nevertheless, don't treat
[dragonfly.git] / bin / ln / ln.c
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1/*
2 * Copyright (c) 1987, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
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32 *
33 * @(#) Copyright (c) 1987, 1993, 1994 The Regents of the University of California. All rights reserved.
34 * @(#)ln.c 8.2 (Berkeley) 3/31/94
35 * $FreeBSD: src/bin/ln/ln.c,v 1.15.2.4 2002/07/12 07:34:38 tjr Exp $
183447a4 36 * $DragonFly: src/bin/ln/ln.c,v 1.11 2006/09/25 09:27:21 corecode Exp $
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37 */
38
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39#include <sys/param.h>
40#include <sys/stat.h>
41
42#include <err.h>
43#include <errno.h>
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44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48
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49static int fflag; /* Unlink existing files. */
50static int hflag; /* Check new name for symlink first. */
51static int iflag; /* Interactive mode. */
52static int sflag; /* Symbolic, not hard, link. */
53static int vflag; /* Verbose output. */
984263bc 54 /* System link call. */
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55static int (*linkf)(const char *, const char *);
56static char linkch;
984263bc 57
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58static int linkit(const char *, const char *, int);
59static void usage(void);
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60
61int
62main(int argc, char *argv[])
63{
64 struct stat sb;
65 char *p, *sourcedir;
66 int ch, exitval;
67
68 /*
69 * Test for the special case where the utility is called as
70 * "link", for which the functionality provided is greatly
71 * simplified.
72 */
17b61719 73 if ((p = strrchr(argv[0], '/')) == NULL)
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74 p = argv[0];
75 else
76 ++p;
77 if (strcmp(p, "link") == 0) {
78 while (getopt(argc, argv, "") != -1)
79 usage();
80 argc -= optind;
81 argv += optind;
82 if (argc != 2)
83 usage();
84 linkf = link;
85 exit(linkit(argv[0], argv[1], 0));
86 }
87
79d50f25 88 while ((ch = getopt(argc, argv, "fhinsv")) != -1) {
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89 switch (ch) {
90 case 'f':
91 fflag = 1;
92 iflag = 0;
93 break;
94 case 'h':
95 case 'n':
96 hflag = 1;
97 break;
98 case 'i':
99 iflag = 1;
100 fflag = 0;
101 break;
102 case 's':
103 sflag = 1;
104 break;
105 case 'v':
106 vflag = 1;
107 break;
108 case '?':
109 default:
110 usage();
111 }
79d50f25 112 }
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113
114 argv += optind;
115 argc -= optind;
116
117 linkf = sflag ? symlink : link;
118 linkch = sflag ? '-' : '=';
119
79d50f25 120 switch (argc) {
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121 case 0:
122 usage();
123 /* NOTREACHED */
124 case 1: /* ln target */
125 exit(linkit(argv[0], ".", 1));
126 case 2: /* ln target source */
127 exit(linkit(argv[0], argv[1], 0));
128 default:
129 ;
130 }
131 /* ln target1 target2 directory */
132 sourcedir = argv[argc - 1];
9814cb62 133 if (hflag && lstat(sourcedir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
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134 /*
135 * We were asked not to follow symlinks, but found one at
136 * the target--simulate "not a directory" error
137 */
1ec7cc4a 138 errc(1, ENOTDIR, "%s", sourcedir);
984263bc 139 }
79d50f25 140 if (stat(sourcedir, &sb) != 0)
9814cb62 141 err(1, "%s", sourcedir);
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142 if (!S_ISDIR(sb.st_mode))
143 usage();
144 for (exitval = 0; *argv != sourcedir; ++argv)
145 exitval |= linkit(*argv, sourcedir, 1);
146 exit(exitval);
147}
148
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149/*
150 * Nomenclature warning!
151 *
152 * In this source "target" and "source" are used the opposite way they
153 * are used in the ln(1) manual. Here "target" is the existing file and
154 * "source" specifies the to-be-created link to "target".
155 */
cdd0b23a 156static int
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157linkit(const char *target, const char *source, int isdir)
158{
159 struct stat sb;
160 const char *p;
161 int ch, exists, first;
162 char path[PATH_MAX];
163
164 if (!sflag) {
165 /* If target doesn't exist, quit now. */
79d50f25 166 if (stat(target, &sb) != 0) {
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167 warn("%s", target);
168 return (1);
169 }
170 /* Only symbolic links to directories. */
171 if (S_ISDIR(sb.st_mode)) {
172 errno = EISDIR;
173 warn("%s", target);
174 return (1);
175 }
176 }
177
178 /*
179 * If the source is a directory (and not a symlink if hflag),
180 * append the target's name.
181 */
182 if (isdir ||
183 (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
184 (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
185 if ((p = strrchr(target, '/')) == NULL)
186 p = target;
187 else
188 ++p;
189 if (snprintf(path, sizeof(path), "%s/%s", source, p) >=
a78cd756 190 (int)sizeof(path)) {
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191 errno = ENAMETOOLONG;
192 warn("%s", target);
193 return (1);
194 }
195 source = path;
196 }
197
79d50f25 198 exists = (lstat(source, &sb) == 0);
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199 /*
200 * If doing hard links and the source (destination) exists and it
201 * actually is the same file like the target (existing file), we
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202 * complain that the files are identical. If -f is specified, we
203 * accept the job as already done and return with success.
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204 */
205 if (exists && !sflag) {
206 struct stat tsb;
207
208 if (stat(target, &tsb) != 0) {
209 warn("%s: disappeared", target);
210 return (1);
211 }
212
213 if (tsb.st_dev == sb.st_dev && tsb.st_ino == sb.st_ino) {
183447a4 214 warnx("%s and %s are identical (not linked).", target, source);
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215 if (fflag)
216 return (0);
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217 else
218 return (1);
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219 }
220 }
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221 /*
222 * If the file exists, then unlink it forcibly if -f was specified
223 * and interactively if -i was specified.
224 */
225 if (fflag && exists) {
79d50f25 226 if (unlink(source) != 0) {
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227 warn("%s", source);
228 return (1);
229 }
230 } else if (iflag && exists) {
231 fflush(stdout);
232 fprintf(stderr, "replace %s? ", source);
233
234 first = ch = getchar();
235 while(ch != '\n' && ch != EOF)
236 ch = getchar();
237 if (first != 'y' && first != 'Y') {
238 fprintf(stderr, "not replaced\n");
239 return (1);
240 }
241
79d50f25 242 if (unlink(source) != 0) {
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243 warn("%s", source);
244 return (1);
245 }
246 }
247
248 /* Attempt the link. */
79d50f25 249 if ((*linkf)(target, source) != 0) {
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250 warn("%s", source);
251 return (1);
252 }
253 if (vflag)
57fed2af 254 printf("%s %c> %s\n", source, linkch, target);
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255 return (0);
256}
257
cdd0b23a 258static void
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259usage(void)
260{
57fed2af 261 fprintf(stderr, "%s\n%s\n%s\n",
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262 "usage: ln [-fhinsv] file1 file2",
263 " ln [-fhinsv] file ... directory",
264 " link file1 file2");
265 exit(1);
266}