1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1987, 1993, 1994
5 * The Regents of the University of California. 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 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #if 0
33 #ifndef lint
34 static char const copyright[] =
35 "@(#) Copyright (c) 1987, 1993, 1994\n\
36 The Regents of the University of California. All rights reserved.\n";
37 #endif /* not lint */
38
39 #ifndef lint
40 static char sccsid[] = "@(#)ln.c 8.2 (Berkeley) 3/31/94";
41 #endif /* not lint */
42 #endif
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
45
46 #include <sys/param.h>
47 #include <sys/stat.h>
48
49 #include <err.h>
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <libgen.h>
53 #include <limits.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <unistd.h>
58
59 static int fflag; /* Unlink existing files. */
60 static int Fflag; /* Remove empty directories also. */
61 static int hflag; /* Check new name for symlink first. */
62 static int iflag; /* Interactive mode. */
63 static int Pflag; /* Create hard links to symlinks. */
64 static int sflag; /* Symbolic, not hard, link. */
65 static int vflag; /* Verbose output. */
66 static int wflag; /* Warn if symlink target does not
67 * exist, and -f is not enabled. */
68 static char linkch;
69
70 static int linkit(const char *, const char *, int);
71 static void usage(void);
72
73 int
main(int argc,char * argv[])74 main(int argc, char *argv[])
75 {
76 struct stat sb;
77 char *p, *targetdir;
78 int ch, exitval;
79
80 /*
81 * Test for the special case where the utility is called as
82 * "link", for which the functionality provided is greatly
83 * simplified.
84 */
85 if ((p = strrchr(argv[0], '/')) == NULL)
86 p = argv[0];
87 else
88 ++p;
89 if (strcmp(p, "link") == 0) {
90 while (getopt(argc, argv, "") != -1)
91 usage();
92 argc -= optind;
93 argv += optind;
94 if (argc != 2)
95 usage();
96 exit(linkit(argv[0], argv[1], 0));
97 }
98
99 while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1)
100 switch (ch) {
101 case 'F':
102 Fflag = 1;
103 break;
104 case 'L':
105 Pflag = 0;
106 break;
107 case 'P':
108 Pflag = 1;
109 break;
110 case 'f':
111 fflag = 1;
112 iflag = 0;
113 wflag = 0;
114 break;
115 case 'h':
116 case 'n':
117 hflag = 1;
118 break;
119 case 'i':
120 iflag = 1;
121 fflag = 0;
122 break;
123 case 's':
124 sflag = 1;
125 break;
126 case 'v':
127 vflag = 1;
128 break;
129 case 'w':
130 wflag = 1;
131 break;
132 case '?':
133 default:
134 usage();
135 }
136
137 argv += optind;
138 argc -= optind;
139
140 linkch = sflag ? '-' : '=';
141 if (sflag == 0)
142 Fflag = 0;
143 if (Fflag == 1 && iflag == 0) {
144 fflag = 1;
145 wflag = 0; /* Implied when fflag != 0 */
146 }
147
148 switch(argc) {
149 case 0:
150 usage();
151 /* NOTREACHED */
152 case 1: /* ln source */
153 exit(linkit(argv[0], ".", 1));
154 case 2: /* ln source target */
155 exit(linkit(argv[0], argv[1], 0));
156 default:
157 ;
158 }
159 /* ln source1 source2 directory */
160 targetdir = argv[argc - 1];
161 if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
162 /*
163 * We were asked not to follow symlinks, but found one at
164 * the target--simulate "not a directory" error
165 */
166 errno = ENOTDIR;
167 err(1, "%s", targetdir);
168 }
169 if (stat(targetdir, &sb))
170 err(1, "%s", targetdir);
171 if (!S_ISDIR(sb.st_mode))
172 usage();
173 for (exitval = 0; *argv != targetdir; ++argv)
174 exitval |= linkit(*argv, targetdir, 1);
175 exit(exitval);
176 }
177
178 /*
179 * Two pathnames refer to the same directory entry if the directories match
180 * and the final components' names match.
181 */
182 static int
samedirent(const char * path1,const char * path2)183 samedirent(const char *path1, const char *path2)
184 {
185 const char *file1, *file2;
186 char pathbuf[PATH_MAX];
187 struct stat sb1, sb2;
188
189 if (strcmp(path1, path2) == 0)
190 return 1;
191 file1 = strrchr(path1, '/');
192 if (file1 != NULL)
193 file1++;
194 else
195 file1 = path1;
196 file2 = strrchr(path2, '/');
197 if (file2 != NULL)
198 file2++;
199 else
200 file2 = path2;
201 if (strcmp(file1, file2) != 0)
202 return 0;
203 if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
204 return 0;
205 if (file1 == path1)
206 memcpy(pathbuf, ".", 2);
207 else {
208 memcpy(pathbuf, path1, file1 - path1);
209 pathbuf[file1 - path1] = '\0';
210 }
211 if (stat(pathbuf, &sb1) != 0)
212 return 0;
213 if (file2 == path2)
214 memcpy(pathbuf, ".", 2);
215 else {
216 memcpy(pathbuf, path2, file2 - path2);
217 pathbuf[file2 - path2] = '\0';
218 }
219 if (stat(pathbuf, &sb2) != 0)
220 return 0;
221 return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
222 }
223
224 static int
linkit(const char * source,const char * target,int isdir)225 linkit(const char *source, const char *target, int isdir)
226 {
227 struct stat sb;
228 const char *p;
229 int ch, exists, first;
230 char path[PATH_MAX];
231 char wbuf[PATH_MAX];
232 char bbuf[PATH_MAX];
233
234 if (!sflag) {
235 /* If source doesn't exist, quit now. */
236 if ((Pflag ? lstat : stat)(source, &sb)) {
237 warn("%s", source);
238 return (1);
239 }
240 /* Only symbolic links to directories. */
241 if (S_ISDIR(sb.st_mode)) {
242 errno = EISDIR;
243 warn("%s", source);
244 return (1);
245 }
246 }
247
248 /*
249 * If the target is a directory (and not a symlink if hflag),
250 * append the source's name, unless Fflag is set.
251 */
252 if (!Fflag && (isdir ||
253 (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
254 (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode)))) {
255 if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) ||
256 (p = basename(bbuf)) == NULL ||
257 snprintf(path, sizeof(path), "%s/%s", target, p) >=
258 (ssize_t)sizeof(path)) {
259 errno = ENAMETOOLONG;
260 warn("%s", source);
261 return (1);
262 }
263 target = path;
264 }
265
266 /*
267 * If the link source doesn't exist, and a symbolic link was
268 * requested, and -w was specified, give a warning.
269 */
270 if (sflag && wflag) {
271 if (*source == '/') {
272 /* Absolute link source. */
273 if (stat(source, &sb) != 0)
274 warn("warning: %s inaccessible", source);
275 } else {
276 /*
277 * Relative symlink source. Try to construct the
278 * absolute path of the source, by appending `source'
279 * to the parent directory of the target.
280 */
281 strlcpy(bbuf, target, sizeof(bbuf));
282 p = dirname(bbuf);
283 if (p != NULL) {
284 (void)snprintf(wbuf, sizeof(wbuf), "%s/%s",
285 p, source);
286 if (stat(wbuf, &sb) != 0)
287 warn("warning: %s", source);
288 }
289 }
290 }
291
292 /*
293 * If the file exists, first check it is not the same directory entry.
294 */
295 exists = !lstat(target, &sb);
296 if (exists) {
297 if (!sflag && samedirent(source, target)) {
298 warnx("%s and %s are the same directory entry",
299 source, target);
300 return (1);
301 }
302 }
303 /*
304 * Then unlink it forcibly if -f was specified
305 * and interactively if -i was specified.
306 */
307 if (fflag && exists) {
308 if (Fflag && S_ISDIR(sb.st_mode)) {
309 if (rmdir(target)) {
310 warn("%s", target);
311 return (1);
312 }
313 } else if (unlink(target)) {
314 warn("%s", target);
315 return (1);
316 }
317 } else if (iflag && exists) {
318 fflush(stdout);
319 fprintf(stderr, "replace %s? ", target);
320
321 first = ch = getchar();
322 while(ch != '\n' && ch != EOF)
323 ch = getchar();
324 if (first != 'y' && first != 'Y') {
325 fprintf(stderr, "not replaced\n");
326 return (1);
327 }
328
329 if (Fflag && S_ISDIR(sb.st_mode)) {
330 if (rmdir(target)) {
331 warn("%s", target);
332 return (1);
333 }
334 } else if (unlink(target)) {
335 warn("%s", target);
336 return (1);
337 }
338 }
339
340 /* Attempt the link. */
341 if (sflag ? symlink(source, target) :
342 linkat(AT_FDCWD, source, AT_FDCWD, target,
343 Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
344 warn("%s", target);
345 return (1);
346 }
347 if (vflag)
348 (void)printf("%s %c> %s\n", target, linkch, source);
349 return (0);
350 }
351
352 static void
usage(void)353 usage(void)
354 {
355 (void)fprintf(stderr, "%s\n%s\n%s\n",
356 "usage: ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]",
357 " ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir",
358 " link source_file target_file");
359 exit(1);
360 }
361