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 1.9 2005/03/16 07:08:04 cpressey 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 static int
 150 linkit(const char *target, const char *source, int isdir)
 151 {
 152         struct stat sb;
 153         const char *p;
 154         int ch, exists, first;
 155         char path[PATH_MAX];
 156
 157         if (!sflag) {
 158                 /* If target doesn't exist, quit now. */
 159                 if (stat(target, &sb) != 0) {
 160                         warn("%s", target);
 161                         return (1);
 162                 }
 163                 /* Only symbolic links to directories. */
 164                 if (S_ISDIR(sb.st_mode)) {
 165                         errno = EISDIR;
 166                         warn("%s", target);
 167                         return (1);
 168                 }
 169         }
 170
 171         /*
 172          * If the source is a directory (and not a symlink if hflag),
 173          * append the target's name.
 174          */
 175         if (isdir ||
 176             (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
 177             (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
 178                 if ((p = strrchr(target, '/')) == NULL)
 179                         p = target;
 180                 else
 181                         ++p;
 182                 if (snprintf(path, sizeof(path), "%s/%s", source, p) >=
 183                     (int)sizeof(path)) {
 184                         errno = ENAMETOOLONG;
 185                         warn("%s", target);
 186                         return (1);
 187                 }
 188                 source = path;
 189         }
 190
 191         exists = (lstat(source, &sb) == 0);
 192         /*
 193          * If the file exists, then unlink it forcibly if -f was specified
 194          * and interactively if -i was specified.
 195          */
 196         if (fflag && exists) {
 197                 if (unlink(source) != 0) {
 198                         warn("%s", source);
 199                         return (1);
 200                 }
 201         } else if (iflag && exists) {
 202                 fflush(stdout);
 203                 fprintf(stderr, "replace %s? ", source);
 204
 205                 first = ch = getchar();
 206                 while(ch != '\n' && ch != EOF)
 207                         ch = getchar();
 208                 if (first != 'y' && first != 'Y') {
 209                         fprintf(stderr, "not replaced\n");
 210                         return (1);
 211                 }
 212
 213                 if (unlink(source) != 0) {
 214                         warn("%s", source);
 215                         return (1);
 216                 }
 217         }
 218
 219         /* Attempt the link. */
 220         if ((*linkf)(target, source) != 0) {
 221                 warn("%s", source);
 222                 return (1);
 223         }
 224         if (vflag)
 225                 printf("%s %c> %s\n", source, linkch, target);
 226         return (0);
 227 }
 228
 229 static void
 230 usage(void)
 231 {
 232         fprintf(stderr, "%s\n%s\n%s\n",
 233             "usage: ln [-fhinsv] file1 file2",
 234             "       ln [-fhinsv] file ... directory",
 235             "       link file1 file2");
 236         exit(1);
 237 }