1 /* $NetBSD: ln.c,v 1.40 2018/08/26 23:01:06 sevan Exp $ */
2
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 #ifdef __FBSDID
45 __FBSDID("$FreeBSD: head/bin/ln/ln.c 251261 2013-06-02 17:55:00Z eadler $");
46 #endif
47 __RCSID("$NetBSD: ln.c,v 1.40 2018/08/26 23:01:06 sevan Exp $");
48
49 #include <sys/param.h>
50 #include <sys/stat.h>
51
52 #include <err.h>
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <libgen.h>
56 #include <limits.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <unistd.h>
61
62 static int fflag; /* Unlink existing files. */
63 static int Fflag; /* Remove empty directories also. */
64 static int hflag; /* Check new name for symlink first. */
65 static int iflag; /* Interactive mode. */
66 static int Pflag; /* Create hard links to symlinks. */
67 static int sflag; /* Symbolic, not hard, link. */
68 static int vflag; /* Verbose output. */
69 static int wflag; /* Warn if symlink target does not
70 * exist, and -f is not enabled. */
71 static char linkch;
72
73 static int linkit(const char *, const char *, int);
74 static __dead void usage(void);
75
76 int
main(int argc,char * argv[])77 main(int argc, char *argv[])
78 {
79 struct stat sb;
80 char *p, *targetdir;
81 int ch, exitval;
82
83 /*
84 * Test for the special case where the utility is called as
85 * "link", for which the functionality provided is greatly
86 * simplified.
87 */
88 if ((p = strrchr(argv[0], '/')) == NULL)
89 p = argv[0];
90 else
91 ++p;
92 if (strcmp(p, "link") == 0) {
93 while (getopt(argc, argv, "") != -1)
94 usage();
95 argc -= optind;
96 argv += optind;
97 if (argc != 2)
98 usage();
99 if (link(argv[0], argv[1]) == -1)
100 err(EXIT_FAILURE, NULL);
101 exit(EXIT_SUCCESS);
102 }
103
104 while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1)
105 switch (ch) {
106 case 'F':
107 Fflag = 1;
108 break;
109 case 'L':
110 Pflag = 0;
111 break;
112 case 'P':
113 Pflag = 1;
114 break;
115 case 'f':
116 fflag = 1;
117 iflag = 0;
118 wflag = 0;
119 break;
120 case 'h':
121 case 'n':
122 hflag = 1;
123 break;
124 case 'i':
125 iflag = 1;
126 fflag = 0;
127 break;
128 case 's':
129 sflag = 1;
130 break;
131 case 'v':
132 vflag = 1;
133 break;
134 case 'w':
135 wflag = 1;
136 break;
137 case '?':
138 default:
139 usage();
140 }
141
142 argv += optind;
143 argc -= optind;
144
145 linkch = sflag ? '-' : '=';
146 if (sflag == 0)
147 Fflag = 0;
148 if (Fflag == 1 && iflag == 0) {
149 fflag = 1;
150 wflag = 0; /* Implied when fflag != 0 */
151 }
152
153 switch(argc) {
154 case 0:
155 usage();
156 /* NOTREACHED */
157 case 1: /* ln source */
158 exit(linkit(argv[0], ".", 1));
159 case 2: /* ln source target */
160 exit(linkit(argv[0], argv[1], 0));
161 default:
162 ;
163 }
164 /* ln source1 source2 directory */
165 targetdir = argv[argc - 1];
166 if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
167 /*
168 * We were asked not to follow symlinks, but found one at
169 * the target--simulate "not a directory" error
170 */
171 errno = ENOTDIR;
172 err(1, "%s", targetdir);
173 }
174 if (stat(targetdir, &sb))
175 err(1, "%s", targetdir);
176 if (!S_ISDIR(sb.st_mode))
177 usage();
178 for (exitval = 0; *argv != targetdir; ++argv)
179 exitval |= linkit(*argv, targetdir, 1);
180 exit(exitval);
181 }
182
183 /*
184 * Two pathnames refer to the same directory entry if the directories match
185 * and the final components' names match.
186 */
187 static int
samedirent(const char * path1,const char * path2)188 samedirent(const char *path1, const char *path2)
189 {
190 const char *file1, *file2;
191 char pathbuf[PATH_MAX];
192 struct stat sb1, sb2;
193
194 if (strcmp(path1, path2) == 0)
195 return 1;
196 file1 = strrchr(path1, '/');
197 if (file1 != NULL)
198 file1++;
199 else
200 file1 = path1;
201 file2 = strrchr(path2, '/');
202 if (file2 != NULL)
203 file2++;
204 else
205 file2 = path2;
206 if (strcmp(file1, file2) != 0)
207 return 0;
208 if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
209 return 0;
210 if (file1 == path1)
211 memcpy(pathbuf, ".", 2);
212 else {
213 memcpy(pathbuf, path1, file1 - path1);
214 pathbuf[file1 - path1] = '\0';
215 }
216 if (stat(pathbuf, &sb1) != 0)
217 return 0;
218 if (file2 == path2)
219 memcpy(pathbuf, ".", 2);
220 else {
221 memcpy(pathbuf, path2, file2 - path2);
222 pathbuf[file2 - path2] = '\0';
223 }
224 if (stat(pathbuf, &sb2) != 0)
225 return 0;
226 return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
227 }
228
229 static int
linkit(const char * source,const char * target,int isdir)230 linkit(const char *source, const char *target, int isdir)
231 {
232 struct stat sb;
233 const char *p;
234 int ch, exists, first;
235 char path[PATH_MAX];
236 char wbuf[PATH_MAX];
237 char bbuf[PATH_MAX];
238
239 if (!sflag) {
240 /* If source doesn't exist, quit now. */
241 if ((Pflag ? lstat : stat)(source, &sb)) {
242 warn("%s", source);
243 return (1);
244 }
245 /* Only symbolic links to directories. */
246 if (S_ISDIR(sb.st_mode)) {
247 errno = EISDIR;
248 warn("%s", source);
249 return (1);
250 }
251 }
252
253 /*
254 * If the target is a directory (and not a symlink if hflag),
255 * append the source's name.
256 */
257 if (isdir ||
258 (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
259 (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) {
260 if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) ||
261 (p = basename(bbuf)) == NULL ||
262 snprintf(path, sizeof(path), "%s/%s", target, p) >=
263 (ssize_t)sizeof(path)) {
264 errno = ENAMETOOLONG;
265 warn("%s", source);
266 return (1);
267 }
268 target = path;
269 }
270
271 /*
272 * If the link source doesn't exist, and a symbolic link was
273 * requested, and -w was specified, give a warning.
274 */
275 if (sflag && wflag) {
276 if (*source == '/') {
277 /* Absolute link source. */
278 if (stat(source, &sb) != 0)
279 warn("warning: %s inaccessible", source);
280 } else {
281 /*
282 * Relative symlink source. Try to construct the
283 * absolute path of the source, by appending `source'
284 * to the parent directory of the target.
285 */
286 strlcpy(bbuf, target, sizeof(bbuf));
287 p = dirname(bbuf);
288 if (p != NULL) {
289 (void)snprintf(wbuf, sizeof(wbuf), "%s/%s",
290 p, source);
291 if (stat(wbuf, &sb) != 0)
292 warn("warning: %s", source);
293 }
294 }
295 }
296
297 /*
298 * If the file exists, first check it is not the same directory entry.
299 */
300 exists = !lstat(target, &sb);
301 if (exists) {
302 if (!sflag && samedirent(source, target)) {
303 warnx("%s and %s are the same directory entry",
304 source, target);
305 return (1);
306 }
307 }
308 /*
309 * Then unlink it forcibly if -f was specified
310 * and interactively if -i was specified.
311 */
312 if (fflag && exists) {
313 if (Fflag && S_ISDIR(sb.st_mode)) {
314 if (rmdir(target)) {
315 warn("%s", target);
316 return (1);
317 }
318 } else if (unlink(target)) {
319 warn("%s", target);
320 return (1);
321 }
322 } else if (iflag && exists) {
323 fflush(stdout);
324 fprintf(stderr, "replace %s? ", target);
325
326 first = ch = getchar();
327 while(ch != '\n' && ch != EOF)
328 ch = getchar();
329 if (first != 'y' && first != 'Y') {
330 fprintf(stderr, "not replaced\n");
331 return (1);
332 }
333
334 if (Fflag && S_ISDIR(sb.st_mode)) {
335 if (rmdir(target)) {
336 warn("%s", target);
337 return (1);
338 }
339 } else if (unlink(target)) {
340 warn("%s", target);
341 return (1);
342 }
343 }
344
345 /* Attempt the link. */
346 if (sflag ? symlink(source, target) :
347 linkat(AT_FDCWD, source, AT_FDCWD, target,
348 Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
349 warn("%s", target);
350 return (1);
351 }
352 if (vflag)
353 (void)printf("%s %c> %s\n", target, linkch, source);
354 return (0);
355 }
356
357 static __dead void
usage(void)358 usage(void)
359 {
360 (void)fprintf(stderr,
361 "usage: %s [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file [target_file]\n"
362 " %s [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file ... target_dir\n"
363 " link source_file target_file\n", getprogname(), getprogname());
364 exit(1);
365 }
366