ln.c revision 173702 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if 0
31#ifndef lint
32static char const copyright[] =
33"@(#) Copyright (c) 1987, 1993, 1994\n\
34	The Regents of the University of California.  All rights reserved.\n";
35#endif /* not lint */
36
37#ifndef lint
38static char sccsid[] = "@(#)ln.c	8.2 (Berkeley) 3/31/94";
39#endif /* not lint */
40#endif
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: head/bin/ln/ln.c 173702 2007-11-17 21:01:22Z ru $");
43
44#include <sys/param.h>
45#include <sys/stat.h>
46
47#include <err.h>
48#include <errno.h>
49#include <limits.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <unistd.h>
54
55int	fflag;				/* Unlink existing files. */
56int	Fflag;				/* Remove empty directories also. */
57int	hflag;				/* Check new name for symlink first. */
58int	iflag;				/* Interactive mode. */
59int	sflag;				/* Symbolic, not hard, link. */
60int	vflag;				/* Verbose output. */
61					/* System link call. */
62int (*linkf)(const char *, const char *);
63char	linkch;
64
65int	linkit(const char *, const char *, int);
66void	usage(void);
67
68int
69main(int argc, char *argv[])
70{
71	struct stat sb;
72	char *p, *targetdir;
73	int ch, exitval;
74
75	/*
76	 * Test for the special case where the utility is called as
77	 * "link", for which the functionality provided is greatly
78	 * simplified.
79	 */
80	if ((p = rindex(argv[0], '/')) == NULL)
81		p = argv[0];
82	else
83		++p;
84	if (strcmp(p, "link") == 0) {
85		while (getopt(argc, argv, "") != -1)
86			usage();
87		argc -= optind;
88		argv += optind;
89		if (argc != 2)
90			usage();
91		linkf = link;
92		exit(linkit(argv[0], argv[1], 0));
93	}
94
95	while ((ch = getopt(argc, argv, "Ffhinsv")) != -1)
96		switch (ch) {
97		case 'F':
98			Fflag = 1;
99			break;
100		case 'f':
101			fflag = 1;
102			iflag = 0;
103			break;
104		case 'h':
105		case 'n':
106			hflag = 1;
107			break;
108		case 'i':
109			iflag = 1;
110			fflag = 0;
111			break;
112		case 's':
113			sflag = 1;
114			break;
115		case 'v':
116			vflag = 1;
117			break;
118		case '?':
119		default:
120			usage();
121		}
122
123	argv += optind;
124	argc -= optind;
125
126	linkf = sflag ? symlink : link;
127	linkch = sflag ? '-' : '=';
128	if (sflag == 0)
129		Fflag = 0;
130	if (Fflag == 1 && iflag == 0)
131		fflag = 1;
132
133	switch(argc) {
134	case 0:
135		usage();
136		/* NOTREACHED */
137	case 1:				/* ln source */
138		exit(linkit(argv[0], ".", 1));
139	case 2:				/* ln source target */
140		exit(linkit(argv[0], argv[1], 0));
141	default:
142		;
143	}
144					/* ln source1 source2 directory */
145	targetdir = argv[argc - 1];
146	if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
147		/*
148		 * We were asked not to follow symlinks, but found one at
149		 * the target--simulate "not a directory" error
150		 */
151		errno = ENOTDIR;
152		err(1, "%s", targetdir);
153	}
154	if (stat(targetdir, &sb))
155		err(1, "%s", targetdir);
156	if (!S_ISDIR(sb.st_mode))
157		usage();
158	for (exitval = 0; *argv != targetdir; ++argv)
159		exitval |= linkit(*argv, targetdir, 1);
160	exit(exitval);
161}
162
163int
164linkit(const char *source, const char *target, int isdir)
165{
166	struct stat sb;
167	const char *p;
168	int ch, exists, first;
169	char path[PATH_MAX];
170
171	if (!sflag) {
172		/* If source doesn't exist, quit now. */
173		if (stat(source, &sb)) {
174			warn("%s", source);
175			return (1);
176		}
177		/* Only symbolic links to directories. */
178		if (S_ISDIR(sb.st_mode)) {
179			errno = EISDIR;
180			warn("%s", source);
181			return (1);
182		}
183	}
184
185	/*
186	 * If the target is a directory (and not a symlink if hflag),
187	 * append the source's name.
188	 */
189	if (isdir ||
190	    (lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
191	    (!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) {
192		if ((p = strrchr(source, '/')) == NULL)
193			p = source;
194		else
195			++p;
196		if (snprintf(path, sizeof(path), "%s/%s", target, p) >=
197		    (ssize_t)sizeof(path)) {
198			errno = ENAMETOOLONG;
199			warn("%s", source);
200			return (1);
201		}
202		target = path;
203	}
204
205	exists = !lstat(target, &sb);
206	/*
207	 * If the file exists, then unlink it forcibly if -f was specified
208	 * and interactively if -i was specified.
209	 */
210	if (fflag && exists) {
211		if (Fflag && S_ISDIR(sb.st_mode)) {
212			if (rmdir(target)) {
213				warn("%s", target);
214				return (1);
215			}
216		} else if (unlink(target)) {
217			warn("%s", target);
218			return (1);
219		}
220	} else if (iflag && exists) {
221		fflush(stdout);
222		fprintf(stderr, "replace %s? ", target);
223
224		first = ch = getchar();
225		while(ch != '\n' && ch != EOF)
226			ch = getchar();
227		if (first != 'y' && first != 'Y') {
228			fprintf(stderr, "not replaced\n");
229			return (1);
230		}
231
232		if (Fflag && S_ISDIR(sb.st_mode)) {
233			if (rmdir(target)) {
234				warn("%s", target);
235				return (1);
236			}
237		} else if (unlink(target)) {
238			warn("%s", target);
239			return (1);
240		}
241	}
242
243	/* Attempt the link. */
244	if ((*linkf)(source, target)) {
245		warn("%s", target);
246		return (1);
247	}
248	if (vflag)
249		(void)printf("%s %c> %s\n", target, linkch, source);
250	return (0);
251}
252
253void
254usage(void)
255{
256	(void)fprintf(stderr, "%s\n%s\n%s\n",
257	    "usage: ln [-s [-F]] [-f | -i] [-hnv] source_file [target_file]",
258	    "       ln [-s [-F]] [-f | -i] [-hnv] source_file ... target_dir",
259	    "       link source_file target_file");
260	exit(1);
261}
262