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bee7cf9e97
* Give link(1) its own usage message. * Use getprogname(3) instead of rolling our own. * Verify that the target file does not already exist. * Add tests specific to link(1). MFC after: 3 days Sponsored by: Klara, Inc. Reviewed by: allanjude Differential Revision: https://reviews.freebsd.org/D44635
359 lines
8.8 KiB
C
359 lines
8.8 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1987, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <libgen.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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static bool fflag; /* Unlink existing files. */
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static bool Fflag; /* Remove empty directories also. */
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static bool hflag; /* Check new name for symlink first. */
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static bool iflag; /* Interactive mode. */
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static bool Pflag; /* Create hard links to symlinks. */
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static bool sflag; /* Symbolic, not hard, link. */
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static bool vflag; /* Verbose output. */
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static bool wflag; /* Warn if symlink target does not
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* exist, and -f is not enabled. */
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static char linkch;
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static int linkit(const char *, const char *, bool);
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static void link_usage(void) __dead2;
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static void usage(void) __dead2;
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int
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main(int argc, char *argv[])
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{
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struct stat sb;
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char *targetdir;
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int ch, exitval;
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/*
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* Test for the special case where the utility is called as
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* "link", for which the functionality provided is greatly
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* simplified.
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*/
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if (strcmp(getprogname(), "link") == 0) {
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while (getopt(argc, argv, "") != -1)
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link_usage();
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argc -= optind;
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argv += optind;
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if (argc != 2)
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link_usage();
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if (lstat(argv[1], &sb) == 0)
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errc(1, EEXIST, "%s", argv[1]);
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/*
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* We could simply call link(2) here, but linkit()
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* performs additional checks and gives better
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* diagnostics.
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*/
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exit(linkit(argv[0], argv[1], false));
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}
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while ((ch = getopt(argc, argv, "FLPfhinsvw")) != -1)
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switch (ch) {
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case 'F':
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Fflag = true;
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break;
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case 'L':
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Pflag = false;
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break;
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case 'P':
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Pflag = true;
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break;
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case 'f':
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fflag = true;
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iflag = false;
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wflag = false;
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break;
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case 'h':
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case 'n':
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hflag = true;
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break;
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case 'i':
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iflag = true;
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fflag = false;
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break;
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case 's':
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sflag = true;
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break;
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case 'v':
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vflag = true;
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break;
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case 'w':
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wflag = true;
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break;
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case '?':
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default:
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usage();
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}
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argv += optind;
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argc -= optind;
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linkch = sflag ? '-' : '=';
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if (!sflag)
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Fflag = false;
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if (Fflag && !iflag) {
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fflag = true;
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wflag = false; /* Implied when fflag is true */
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}
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switch (argc) {
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case 0:
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usage();
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/* NOTREACHED */
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case 1: /* ln source */
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exit(linkit(argv[0], ".", true));
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case 2: /* ln source target */
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exit(linkit(argv[0], argv[1], false));
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default:
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;
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}
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/* ln source1 source2 directory */
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targetdir = argv[argc - 1];
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if (hflag && lstat(targetdir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
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/*
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* We were asked not to follow symlinks, but found one at
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* the target--simulate "not a directory" error
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*/
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errno = ENOTDIR;
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err(1, "%s", targetdir);
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}
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if (stat(targetdir, &sb))
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err(1, "%s", targetdir);
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if (!S_ISDIR(sb.st_mode))
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usage();
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for (exitval = 0; *argv != targetdir; ++argv)
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exitval |= linkit(*argv, targetdir, true);
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exit(exitval);
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}
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/*
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* Two pathnames refer to the same directory entry if the directories match
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* and the final components' names match.
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*/
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static int
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samedirent(const char *path1, const char *path2)
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{
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const char *file1, *file2;
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char pathbuf[PATH_MAX];
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struct stat sb1, sb2;
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if (strcmp(path1, path2) == 0)
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return 1;
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file1 = strrchr(path1, '/');
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if (file1 != NULL)
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file1++;
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else
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file1 = path1;
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file2 = strrchr(path2, '/');
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if (file2 != NULL)
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file2++;
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else
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file2 = path2;
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if (strcmp(file1, file2) != 0)
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return 0;
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if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
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return 0;
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if (file1 == path1)
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memcpy(pathbuf, ".", 2);
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else {
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memcpy(pathbuf, path1, file1 - path1);
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pathbuf[file1 - path1] = '\0';
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}
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if (stat(pathbuf, &sb1) != 0)
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return 0;
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if (file2 == path2)
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memcpy(pathbuf, ".", 2);
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else {
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memcpy(pathbuf, path2, file2 - path2);
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pathbuf[file2 - path2] = '\0';
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}
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if (stat(pathbuf, &sb2) != 0)
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return 0;
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return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
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}
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static int
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linkit(const char *source, const char *target, bool isdir)
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{
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char path[PATH_MAX];
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char wbuf[PATH_MAX];
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char bbuf[PATH_MAX];
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struct stat sb;
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const char *p;
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int ch, first;
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bool exists;
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if (!sflag) {
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/* If source doesn't exist, quit now. */
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if ((Pflag ? lstat : stat)(source, &sb)) {
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warn("%s", source);
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return (1);
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}
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/* Only symbolic links to directories. */
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if (S_ISDIR(sb.st_mode)) {
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errno = EISDIR;
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warn("%s", source);
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return (1);
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}
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}
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/*
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* If the target is a directory (and not a symlink if hflag),
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* append the source's name, unless Fflag is set.
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*/
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if (!Fflag && (isdir ||
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(lstat(target, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
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(!hflag && stat(target, &sb) == 0 && S_ISDIR(sb.st_mode)))) {
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if (strlcpy(bbuf, source, sizeof(bbuf)) >= sizeof(bbuf) ||
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(p = basename(bbuf)) == NULL ||
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snprintf(path, sizeof(path), "%s/%s", target, p) >=
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(ssize_t)sizeof(path)) {
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errno = ENAMETOOLONG;
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warn("%s", source);
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return (1);
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}
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target = path;
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}
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/*
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* If the link source doesn't exist, and a symbolic link was
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* requested, and -w was specified, give a warning.
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*/
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if (sflag && wflag) {
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if (*source == '/') {
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/* Absolute link source. */
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if (stat(source, &sb) != 0)
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warn("warning: %s inaccessible", source);
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} else {
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/*
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* Relative symlink source. Try to construct the
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* absolute path of the source, by appending `source'
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* to the parent directory of the target.
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*/
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strlcpy(bbuf, target, sizeof(bbuf));
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p = dirname(bbuf);
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if (p != NULL) {
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(void)snprintf(wbuf, sizeof(wbuf), "%s/%s",
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p, source);
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if (stat(wbuf, &sb) != 0)
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warn("warning: %s", source);
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}
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}
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}
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/*
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* If the file exists, first check it is not the same directory entry.
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*/
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exists = lstat(target, &sb) == 0;
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if (exists) {
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if (!sflag && samedirent(source, target)) {
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warnx("%s and %s are the same directory entry",
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source, target);
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return (1);
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}
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}
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/*
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* Then unlink it forcibly if -f was specified
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* and interactively if -i was specified.
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*/
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if (fflag && exists) {
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if (Fflag && S_ISDIR(sb.st_mode)) {
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if (rmdir(target)) {
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warn("%s", target);
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return (1);
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}
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} else if (unlink(target)) {
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warn("%s", target);
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return (1);
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}
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} else if (iflag && exists) {
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fflush(stdout);
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fprintf(stderr, "replace %s? ", target);
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first = ch = getchar();
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while(ch != '\n' && ch != EOF)
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ch = getchar();
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if (first != 'y' && first != 'Y') {
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fprintf(stderr, "not replaced\n");
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return (1);
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}
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if (Fflag && S_ISDIR(sb.st_mode)) {
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if (rmdir(target)) {
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warn("%s", target);
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return (1);
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}
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} else if (unlink(target)) {
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warn("%s", target);
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return (1);
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}
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}
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/* Attempt the link. */
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if (sflag ? symlink(source, target) :
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linkat(AT_FDCWD, source, AT_FDCWD, target,
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Pflag ? 0 : AT_SYMLINK_FOLLOW)) {
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warn("%s", target);
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return (1);
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}
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if (vflag)
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(void)printf("%s %c> %s\n", target, linkch, source);
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return (0);
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}
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static void
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link_usage(void)
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{
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(void)fprintf(stderr, "usage: link source_file target_file\n");
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exit(1);
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}
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static void
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usage(void)
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{
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(void)fprintf(stderr, "%s\n%s\n",
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"usage: ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]",
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" ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir");
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exit(1);
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}
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