bin/ln/ln.c

   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  * @(#) Copyright (c) 1987, 1993, 1994 The Regents of the University of California.  All rights reserved.
  34  * @(#)ln.c     8.2 (Berkeley) 3/31/94
  35  * $FreeBSD: src/bin/ln/ln.c,v 1.15.2.4 2002/07/12 07:34:38 tjr Exp $
  36  * $DragonFly: src/bin/ln/ln.c,v 1.11 2006/09/25 09:27:21 corecode Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/stat.h>
  41
  42 #include <err.h>
  43 #include <errno.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47 #include <unistd.h>
  48
  49 static int      fflag;                          /* Unlink existing files. */
  50 static int      hflag;                          /* Check new name for symlink first. */
  51 static int      iflag;                          /* Interactive mode. */
  52 static int      sflag;                          /* Symbolic, not hard, link. */
  53 static int      vflag;                          /* Verbose output. */
  54                                         /* System link call. */
  55 static int      (*linkf)(const char *, const char *);
  56 static char     linkch;
  57
  58 static int      linkit(const char *, const char *, int);
  59 static void     usage(void);
  60
  61 int
  62 main(int argc, char *argv[])
  63 {
  64         struct stat sb;
  65         char *p, *sourcedir;
  66         int ch, exitval;
  67
  68         /*
  69          * Test for the special case where the utility is called as
  70          * "link", for which the functionality provided is greatly
  71          * simplified.
  72          */
  73         if ((p = strrchr(argv[0], '/')) == NULL)
  74                 p = argv[0];
  75         else
  76                 ++p;
  77         if (strcmp(p, "link") == 0) {
  78                 while (getopt(argc, argv, "") != -1)
  79                         usage();
  80                 argc -= optind;
  81                 argv += optind;
  82                 if (argc != 2)
  83                         usage();
  84                 linkf = link;
  85                 exit(linkit(argv[0], argv[1], 0));
  86         }
  87
  88         while ((ch = getopt(argc, argv, "fhinsv")) != -1) {
  89                 switch (ch) {
  90                 case 'f':
  91                         fflag = 1;
  92                         iflag = 0;
  93                         break;
  94                 case 'h':
  95                 case 'n':
  96                         hflag = 1;
  97                         break;
  98                 case 'i':
  99                         iflag = 1;
 100                         fflag = 0;
 101                         break;
 102                 case 's':
 103                         sflag = 1;
 104                         break;
 105                 case 'v':
 106                         vflag = 1;
 107                         break;
 108                 case '?':
 109                 default:
 110                         usage();
 111                 }
 112         }
 113
 114         argv += optind;
 115         argc -= optind;
 116
 117         linkf = sflag ? symlink : link;
 118         linkch = sflag ? '-' : '=';
 119
 120         switch (argc) {
 121         case 0:
 122                 usage();
 123                 /* NOTREACHED */
 124         case 1:                         /* ln target */
 125                 exit(linkit(argv[0], ".", 1));
 126         case 2:                         /* ln target source */
 127                 exit(linkit(argv[0], argv[1], 0));
 128         default:
 129                 ;
 130         }
 131                                         /* ln target1 target2 directory */
 132         sourcedir = argv[argc - 1];
 133         if (hflag && lstat(sourcedir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
 134                 /*
 135                  * We were asked not to follow symlinks, but found one at
 136                  * the target--simulate "not a directory" error
 137                  */
 138                 errc(1, ENOTDIR, "%s", sourcedir);
 139         }
 140         if (stat(sourcedir, &sb) != 0)
 141                 err(1, "%s", sourcedir);
 142         if (!S_ISDIR(sb.st_mode))
 143                 usage();
 144         for (exitval = 0; *argv != sourcedir; ++argv)
 145                 exitval |= linkit(*argv, sourcedir, 1);
 146         exit(exitval);
 147 }
 148
 149 /*
 150  * Nomenclature warning!
 151  *
 152  * In this source "target" and "source" are used the opposite way they
 153  * are used in the ln(1) manual.  Here "target" is the existing file and
 154  * "source" specifies the to-be-created link to "target".
 155  */
 156 static int
 157 linkit(const char *target, const char *source, int isdir)
 158 {
 159         struct stat sb;
 160         const char *p;
 161         int ch, exists, first;
 162         char path[PATH_MAX];
 163
 164         if (!sflag) {
 165                 /* If target doesn't exist, quit now. */
 166                 if (stat(target, &sb) != 0) {
 167                         warn("%s", target);
 168                         return (1);
 169                 }
 170                 /* Only symbolic links to directories. */
 171                 if (S_ISDIR(sb.st_mode)) {
 172                         errno = EISDIR;
 173                         warn("%s", target);
 174                         return (1);
 175                 }
 176         }
 177
 178         /*
 179          * If the source is a directory (and not a symlink if hflag),
 180          * append the target's name.
 181          */
 182         if (isdir ||
 183             (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
 184             (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
 185                 if ((p = strrchr(target, '/')) == NULL)
 186                         p = target;
 187                 else
 188                         ++p;
 189                 if (snprintf(path, sizeof(path), "%s/%s", source, p) >=
 190                     (int)sizeof(path)) {
 191                         errno = ENAMETOOLONG;
 192                         warn("%s", target);
 193                         return (1);
 194                 }
 195                 source = path;
 196         }
 197
 198         exists = (lstat(source, &sb) == 0);
 199         /*
 200          * If doing hard links and the source (destination) exists and it
 201          * actually is the same file like the target (existing file), we
 202          * complain that the files are identical.  If -f is specified, we
 203          * accept the job as already done and return with success.
 204          */
 205         if (exists && !sflag) {
 206                 struct stat tsb;
 207
 208                 if (stat(target, &tsb) != 0) {
 209                         warn("%s: disappeared", target);
 210                         return (1);
 211                 }
 212
 213                 if (tsb.st_dev == sb.st_dev && tsb.st_ino == sb.st_ino) {
 214                         warnx("%s and %s are identical (not linked).", target, source);
 215                         if (fflag)
 216                                 return (0);
 217                         else
 218                                 return (1);
 219                 }
 220         }
 221         /*
 222          * If the file exists, then unlink it forcibly if -f was specified
 223          * and interactively if -i was specified.
 224          */
 225         if (fflag && exists) {
 226                 if (unlink(source) != 0) {
 227                         warn("%s", source);
 228                         return (1);
 229                 }
 230         } else if (iflag && exists) {
 231                 fflush(stdout);
 232                 fprintf(stderr, "replace %s? ", source);
 233
 234                 first = ch = getchar();
 235                 while(ch != '\n' && ch != EOF)
 236                         ch = getchar();
 237                 if (first != 'y' && first != 'Y') {
 238                         fprintf(stderr, "not replaced\n");
 239                         return (1);
 240                 }
 241
 242                 if (unlink(source) != 0) {
 243                         warn("%s", source);
 244                         return (1);
 245                 }
 246         }
 247
 248         /* Attempt the link. */
 249         if ((*linkf)(target, source) != 0) {
 250                 warn("%s", source);
 251                 return (1);
 252         }
 253         if (vflag)
 254                 printf("%s %c> %s\n", source, linkch, target);
 255         return (0);
 256 }
 257
 258 static void
 259 usage(void)
 260 {
 261         fprintf(stderr, "%s\n%s\n%s\n",
 262             "usage: ln [-fhinsv] source_file [target_file]",
 263             "       ln [-fhinsv] source_file ... target_dir",
 264             "       link source_file target_file");
 265         exit(1);
 266 }