/* $NetBSD: ln.c,v 1.40 2018/08/26 23:01:06 sevan Exp $ */
/*-
* 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. 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.
*/
#include <sys/param.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <stdio.h>
#include <bsd/stdlib.h>
#include <string.h>
#include <unistd.h>
static int fflag; /* Unlink existing files. */
static int Fflag; /* Remove empty directories also. */
static int hflag; /* Check new name for symlink first. */
static int iflag; /* Interactive mode. */
static int Pflag; /* Create hard links to symlinks. */
static int sflag; /* Symbolic, not hard, link. */
static int vflag; /* Verbose output. */
static int wflag; /* Warn if symlink target does not
* exist, and -f is not enabled. */
static char linkch;
static int linkit(const char *, const char *, int);
static void usage(void);
int
main(int argc, char *argv[])
{
struct stat sb;
char *p, *targetdir;
int ch, exitval;
/*
* Test for the special case where the utility is called as
* "link", for which the functionality provided is greatly
* simplified.
*/
if ((p = strrchr(argv[0], '/')) == NULL)
p = argv[0];
else
++p;
if (strcmp(p, "link") == 0) {
while (getopt(argc, argv, "") != -1)
usage();
argc -= optind;
argv += optind;
if (argc != 2)
usage();
if (link(argv[0], argv[1]) == -1)
err(EXIT_FAILURE, NULL);
exit(EXIT_SUCCESS);
}
while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1)
switch (ch) {
case 'F':
Fflag = 1;
break;
case 'L':
Pflag = 0;
break;
case 'P':
Pflag = 1;
break;
case 'f':
fflag = 1;
iflag = 0;
wflag = 0;
break;
case 'h':
case 'n':
hflag = 1;
break;
case 'i':
iflag = 1;
fflag = 0;
break;
case 's':
sflag = 1;
break;
case 'v':
vflag = 1;
break;
case 'w':
wflag = 1;
break;
case '?':
default:
usage();
}
argv += optind;
argc -= optind;
linkch = sflag ? '-' : '=';
if (sflag == 0)
Fflag = 0;
if (Fflag == 1 && iflag == 0) {
fflag = 1;
wflag = 0; /* Implied when fflag != 0 */
}
switch(argc) {
case 0:
usage();
/* NOTREACHED */
case 1: /* ln source */
exit(linkit(argv[0], ".", 1));
case 2: /* ln source target */
exit(linkit(argv[0], argv[1], 0));
default:
;
}
/* ln source1 source2 directory */
targetdir = argv[argc - 1];
if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
/*
* We were asked not to follow symlinks, but found one at
* the target--simulate "not a directory" error
*/
errno = ENOTDIR;
err(1, "%s", targetdir);
}
if (stat(targetdir, &sb))
err(1, "%s", targetdir);
if (!S_ISDIR(sb.st_mode))
usage();
for (exitval = 0; *argv != targetdir; ++argv)
exitval |= linkit(*argv, targetdir, 1);
exit(exitval);
}
/*
* Two pathnames refer to the same directory entry if the directories match
* and the final components' names match.
*/
static int
samedirent(const char *path1, const char *path2)
{
const char *file1, *file2;
char pathbuf[PATH_MAX];
struct stat sb1, sb2;
if (strcmp(path1, path2) == 0)
return 1;
file1 = strrchr(path1, '/');
if (file1 != NULL)
file1++;
else
file1 = path1;
file2 = strrchr(path2, '/');
if (file2 != NULL)
file2++;
else
file2 = path2;
if (strcmp(file1, file2) != 0)
return 0;
if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
return 0;
if (file1 == path1)
memcpy(pathbuf, ".", 2);
else {
memcpy(pathbuf, path1, file1 - path1);
pathbuf[file1 - path1] = '\0';
}
if (stat(pathbuf, &sb1) != 0)
return 0;
if (file2 == path2)
memcpy(pathbuf, ".", 2);
else {
memcpy(pathbuf, path2, file2 - path2);
pathbuf[file2 - path2] = '\0';
}
if (stat(pathbuf, &sb2) != 0)
return 0;
return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
}
static int
linkit(const char *source, const char *target, int isdir)
{
struct stat sb;
const char *p;
int ch, exists, first;
char path[PATH_MAX];
char wbuf[PATH_MAX];
char bbuf[PATH_MAX];
if (!sflag) {
/* If source doesn't exist, quit now. */
if ((Pflag ? lstat : stat)(source, &sb)) {
warn("%s", source);
return (1);
}
/* Only symbolic links to directories. */
if (S_ISDIR(sb.st_mode)) {
errno = EISDIR;
warn("%s", source);
return (1);
}
}
/*
* If the target is a directory (and not a symlink if hflag),
* append the source's name.
*/
if (isdir ||
(lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
(!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode))) {
if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) ||
(p = basename(bbuf)) == NULL ||
snprintf(path, sizeof(path), "%s/%s", target, p) >=
(ssize_t)sizeof(path)) {
errno = ENAMETOOLONG;
warn("%s", source);
return (1);
}
target = path;
}
/*
* If the link source doesn't exist, and a symbolic link was
* requested, and -w was specified, give a warning.
*/
if (sflag && wflag) {
if (*source == '/') {
/* Absolute link source. */
if (stat(source, &sb) != 0)
warn("warning: %s inaccessible", source);
} else {
/*
* Relative symlink source. Try to construct the
* absolute path of the source, by appending `source'
* to the parent directory of the target.
*/
strlcpy(bbuf, target, sizeof(bbuf));
p = dirname(bbuf);
if (p != NULL) {
(void)snprintf(wbuf, sizeof(wbuf), "%s/%s",
p, source);
if (stat(wbuf, &sb) != 0)
warn("warning: %s", source);
}
}
}
/*
* If the file exists, first check it is not the same directory entry.
*/
exists = !lstat(target, &sb);
if (exists) {
if (!sflag && samedirent(source, target)) {
warnx("%s and %s are the same directory entry",
source, target);
return (1);
}
}
/*
* Then unlink it forcibly if -f was specified
* and interactively if -i was specified.
*/
if (fflag && exists) {
if (Fflag && S_ISDIR(sb.st_mode)) {
if (rmdir(target)) {
warn("%s", target);
return (1);
}
} else if (unlink(target)) {
warn("%s", target);
return (1);
}
} else if (iflag && exists) {
fflush(stdout);
fprintf(stderr, "replace %s? ", target);
first = ch = getchar();
while(ch != '\n' && ch != EOF)
ch = getchar();
if (first != 'y' && first != 'Y') {
fprintf(stderr, "not replaced\n");
return (1);
}
if (Fflag && S_ISDIR(sb.st_mode)) {
if (rmdir(target)) {
warn("%s", target);
return (1);
}
} else if (unlink(target)) {
warn("%s", target);
return (1);
}
}
/* Attempt the link. */
if (sflag ? symlink(source, target) :
linkat(AT_FDCWD, source, AT_FDCWD, target,
Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
warn("%s", target);
return (1);
}
if (vflag)
(void)printf("%s %c> %s\n", target, linkch, source);
return (0);
}
static void
usage(void)
{
(void)fprintf(stderr,
"usage: %s [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file [target_file]\n"
" %s [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file ... target_dir\n"
" link source_file target_file\n", getprogname(), getprogname());
exit(1);
}
