ln.c revision 91084 
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.
32 */
33
34#ifndef lint
35static char const copyright[] =
36"@(#) Copyright (c) 1987, 1993, 1994\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)ln.c	8.2 (Berkeley) 3/31/94";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/bin/ln/ln.c 91084 2002-02-22 21:11:03Z markm $";
46#endif /* not lint */
47
48#include <sys/param.h>
49#include <sys/stat.h>
50
51#include <err.h>
52#include <errno.h>
53#include <limits.h>
54#include <stdio.h>
55#include <stdlib.h>
56#include <string.h>
57#include <unistd.h>
58
59int	fflag;				/* Unlink existing files. */
60int	hflag;				/* Check new name for symlink first. */
61int	iflag;				/* Interactive mode. */
62int	sflag;				/* Symbolic, not hard, link. */
63int	vflag;				/* Verbose output. */
64					/* System link call. */
65int (*linkf)(const char *, const char *);
66char	linkch;
67
68int	linkit(const char *, const char *, int);
69void	usage(void);
70
71int
72main(int argc, char *argv[])
73{
74	struct stat sb;
75	char *p, *sourcedir;
76	int ch, exitval;
77
78	/*
79	 * Test for the special case where the utility is called as
80	 * "link", for which the functionality provided is greatly
81	 * simplified.
82	 */
83	if ((p = rindex(argv[0], '/')) == NULL)
84		p = argv[0];
85	else
86		++p;
87	if (strcmp(p, "link") == 0) {
88		if (argc == 3) {
89			linkf = link;
90			exit(linkit(argv[1], argv[2], 0));
91		} else
92			usage();
93	}
94
95	while ((ch = getopt(argc, argv, "fhinsv")) != -1)
96		switch (ch) {
97		case 'f':
98			fflag = 1;
99			iflag = 0;
100			break;
101		case 'h':
102		case 'n':
103			hflag = 1;
104			break;
105		case 'i':
106			iflag = 1;
107			fflag = 0;
108			break;
109		case 's':
110			sflag = 1;
111			break;
112		case 'v':
113			vflag = 1;
114			break;
115		case '?':
116		default:
117			usage();
118		}
119
120	argv += optind;
121	argc -= optind;
122
123	linkf = sflag ? symlink : link;
124	linkch = sflag ? '-' : '=';
125
126	switch(argc) {
127	case 0:
128		usage();
129		/* NOTREACHED */
130	case 1:				/* ln target */
131		exit(linkit(argv[0], ".", 1));
132	case 2:				/* ln target source */
133		exit(linkit(argv[0], argv[1], 0));
134	default:
135	}
136					/* ln target1 target2 directory */
137	sourcedir = argv[argc - 1];
138	if (hflag && lstat(sourcedir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
139		/*
140		 * We were asked not to follow symlinks, but found one at
141		 * the target--simulate "not a directory" error
142		 */
143		errno = ENOTDIR;
144		err(1, "%s", sourcedir);
145	}
146	if (stat(sourcedir, &sb))
147		err(1, "%s", sourcedir);
148	if (!S_ISDIR(sb.st_mode))
149		usage();
150	for (exitval = 0; *argv != sourcedir; ++argv)
151		exitval |= linkit(*argv, sourcedir, 1);
152	exit(exitval);
153}
154
155int
156linkit(const char *target, const char *source, int isdir)
157{
158	struct stat sb;
159	const char *p;
160	int ch, exists, first;
161	char path[PATH_MAX];
162
163	if (!sflag) {
164		/* If target doesn't exist, quit now. */
165		if (stat(target, &sb)) {
166			warn("%s", target);
167			return (1);
168		}
169		/* Only symbolic links to directories. */
170		if (S_ISDIR(sb.st_mode)) {
171			errno = EISDIR;
172			warn("%s", target);
173			return (1);
174		}
175	}
176
177	/*
178	 * If the source is a directory (and not a symlink if hflag),
179	 * append the target's name.
180	 */
181	if (isdir ||
182	    (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
183	    (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
184		if ((p = strrchr(target, '/')) == NULL)
185			p = target;
186		else
187			++p;
188		(void)snprintf(path, sizeof(path), "%s/%s", source, p);
189		source = path;
190	}
191
192	exists = !lstat(source, &sb);
193	/*
194	 * If the file exists, then unlink it forcibly if -f was specified
195	 * and interactively if -i was specified.
196	 */
197	if (fflag && exists) {
198		if (unlink(source)) {
199			warn("%s", source);
200			return (1);
201		}
202	} else if (iflag && exists) {
203		fflush(stdout);
204		fprintf(stderr, "replace %s? ", source);
205
206		first = ch = getchar();
207		while(ch != '\n' && ch != EOF)
208			ch = getchar();
209		if (first != 'y' && first != 'Y') {
210			fprintf(stderr, "not replaced\n");
211			return (1);
212		}
213
214		if (unlink(source)) {
215			warn("%s", source);
216			return (1);
217		}
218	}
219
220	/* Attempt the link. */
221	if ((*linkf)(target, source)) {
222		warn("%s", source);
223		return (1);
224	}
225	if (vflag)
226		(void)printf("%s %c> %s\n", source, linkch, target);
227	return (0);
228}
229
230void
231usage(void)
232{
233	(void)fprintf(stderr, "%s\n%s\n%s\n",
234	    "usage: ln [-fhinsv] file1 file2",
235	    "       ln [-fhinsv] file ... directory",
236	    "       link file1 file2");
237	exit(1);
238}
239