freebsd-dev/bin/ln/ln.c
Bruce Evans 9195f40982 Use lstat() instead of stat() for checking if the final source file exists,
so that `ln -fs' works when the source is a symlink pointing to a non-
existent file.
1994-12-06 18:50:44 +00:00

167 lines
4.5 KiB
C

/*
* Copyright (c) 1987, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: ln.c,v 1.4 1994/09/24 02:55:48 davidg Exp $
*/
#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1987, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)ln.c 8.2 (Berkeley) 3/31/94";
#endif /* not lint */
#include <sys/param.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int dirflag; /* Undocumented directory flag. */
int fflag; /* Unlink existing files. */
int sflag; /* Symbolic, not hard, link. */
/* System link call. */
int (*linkf) __P((const char *, const char *));
int linkit __P((char *, char *, int));
void usage __P((void));
int
main(argc, argv)
int argc;
char *argv[];
{
extern int optind;
struct stat sb;
int ch, exitval;
char *sourcedir;
while ((ch = getopt(argc, argv, "Ffs")) != EOF)
switch (ch) {
case 'F':
dirflag = 1; /* XXX: deliberately undocumented. */
break;
case 'f':
fflag = 1;
break;
case 's':
sflag = 1;
break;
case '?':
default:
usage();
}
argv += optind;
argc -= optind;
linkf = sflag ? symlink : link;
switch(argc) {
case 0:
usage();
case 1: /* ln target */
exit(linkit(argv[0], ".", 1));
case 2: /* ln target source */
exit(linkit(argv[0], argv[1], 0));
}
/* ln target1 target2 directory */
sourcedir = argv[argc - 1];
if (stat(sourcedir, &sb))
err(1, "%s", sourcedir);
if (!S_ISDIR(sb.st_mode))
usage();
for (exitval = 0; *argv != sourcedir; ++argv)
exitval |= linkit(*argv, sourcedir, 1);
exit(exitval);
}
int
linkit(target, source, isdir)
char *target, *source;
int isdir;
{
struct stat sb;
int exists;
char *p, path[MAXPATHLEN];
if (!sflag) {
/* If target doesn't exist, quit now. */
if (stat(target, &sb)) {
warn("%s", target);
return (1);
}
/* Only symbolic links to directories, unless -F option used. */
if (!dirflag && (sb.st_mode & S_IFMT) == S_IFDIR) {
warnx("%s: is a directory", target);
return (1);
}
}
/* If the source is a directory, append the target's name. */
if (isdir || ((exists = !stat(source, &sb)) && S_ISDIR(sb.st_mode))) {
if ((p = strrchr(target, '/')) == NULL)
p = target;
else
++p;
(void)snprintf(path, sizeof(path), "%s/%s", source, p);
source = path;
exists = !lstat(source, &sb);
} else
exists = !lstat(source, &sb);
/*
* If the file exists, and -f was specified, unlink it.
* Attempt the link.
*/
if ((fflag && exists && unlink(source)) || (*linkf)(target, source)) {
warn("%s", source);
return (1);
}
return (0);
}
void
usage()
{
(void)fprintf(stderr,
"usage:\tln [-fs] file1 file2\n\tln [-fs] file ... directory\n");
exit(1);
}