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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if 0
  31 #ifndef lint
  32 static char const copyright[] =
  33 "@(#) Copyright (c) 1987, 1993, 1994\n\
  34         The Regents of the University of California.  All rights reserved.\n";
  35 #endif /* not lint */
  36
  37 #ifndef lint
  38 static char sccsid[] = "@(#)ln.c        8.2 (Berkeley) 3/31/94";
  39 #endif /* not lint */
  40 #endif
  41 #include <sys/cdefs.h>
  42 __FBSDID("$FreeBSD: src/bin/ln/ln.c,v 1.34 2006/02/14 11:08:05 glebius Exp $");
  43
  44 #include <sys/param.h>
  45 #include <sys/stat.h>
  46
  47 #include <err.h>
  48 #include <errno.h>
  49 #include <libgen.h>
  50 #include <limits.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <unistd.h>
  55
  56 int     fflag;                          /* Unlink existing files. */
  57 int     Fflag;                          /* Remove empty directories also. */
  58 int     hflag;                          /* Check new name for symlink first. */
  59 int     iflag;                          /* Interactive mode. */
  60 int     sflag;                          /* Symbolic, not hard, link. */
  61 int     vflag;                          /* Verbose output. */
  62                                         /* System link call. */
  63 int (*linkf)(const char *, const char *);
  64 char    linkch;
  65
  66 int     linkit(const char *, const char *, int);
  67 void    usage(void);
  68
  69 int
  70 main(int argc, char *argv[])
  71 {
  72         struct stat sb;
  73         char *p, *sourcedir;
  74         int ch, exitval;
  75
  76         if (argc < 1)
  77                 usage();
  78         /*
  79          * Test for the special case where the utility is called as
  80          * "link", for which the functionality provided is greatly
  81          * simplified.
  82          */
  83         if ((p = rindex(argv[0], '/')) == NULL)
  84                 p = argv[0];
  85         else
  86                 ++p;
  87         if (strcmp(p, "link") == 0) {
  88                 while (getopt(argc, argv, "") != -1)
  89                         usage();
  90                 argc -= optind;
  91                 argv += optind;
  92                 if (argc != 2)
  93                         usage();
  94                 linkf = link;
  95                 /* UNIX conformance requires that both operands be NOT a dir */
  96                 for (int i = 0; i < 2; i++) {
  97                         if (stat(argv[i], &sb) == 0 && S_ISDIR(sb.st_mode)){
  98                                 errno = EISDIR;
  99                                 warn("%s", argv[0]);
 100                                 return 1;
 101                         }
 102                 }
 103
 104                 exit(linkit(argv[0], argv[1], 0));
 105         }
 106
 107         while ((ch = getopt(argc, argv, "Ffhinsv")) != -1)
 108                 switch (ch) {
 109                 case 'F':
 110                         Fflag = 1;
 111                         break;
 112                 case 'f':
 113                         fflag = 1;
 114                         iflag = 0;
 115                         break;
 116                 case 'h':
 117                 case 'n':
 118                         hflag = 1;
 119                         break;
 120                 case 'i':
 121                         iflag = 1;
 122                         fflag = 0;
 123                         break;
 124                 case 's':
 125                         sflag = 1;
 126                         break;
 127                 case 'v':
 128                         vflag = 1;
 129                         break;
 130                 case '?':
 131                 default:
 132                         usage();
 133                 }
 134
 135         argv += optind;
 136         argc -= optind;
 137
 138         linkf = sflag ? symlink : link;
 139         linkch = sflag ? '-' : '=';
 140         if (sflag == 0)
 141                 Fflag = 0;
 142         if (Fflag == 1 && iflag == 0)
 143                 fflag = 1;
 144
 145         switch(argc) {
 146         case 0:
 147                 usage();
 148                 /* NOTREACHED */
 149         case 1:                         /* ln target */
 150                 exit(linkit(argv[0], ".", 1));
 151         case 2:                         /* ln target source */
 152                 exit(linkit(argv[0], argv[1], 0));
 153         default:
 154                 ;
 155         }
 156                                         /* ln target1 target2 directory */
 157         sourcedir = argv[argc - 1];
 158         if (hflag && lstat(sourcedir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
 159                 /*
 160                  * We were asked not to follow symlinks, but found one at
 161                  * the target--simulate "not a directory" error
 162                  */
 163                 errno = ENOTDIR;
 164                 err(1, "%s", sourcedir);
 165         }
 166         if (stat(sourcedir, &sb))
 167                 err(1, "%s", sourcedir);
 168         if (!S_ISDIR(sb.st_mode))
 169                 usage();
 170         for (exitval = 0; *argv != sourcedir; ++argv)
 171                 exitval |= linkit(*argv, sourcedir, 1);
 172         exit(exitval);
 173 }
 174
 175 int
 176 linkit(const char *target, const char *source, int isdir)
 177 {
 178         struct stat sb;
 179         const char *p;
 180         int ch, exists, first;
 181         char path[PATH_MAX];
 182         char bbuf[PATH_MAX];
 183
 184         if (!sflag) {
 185                 /* If target doesn't exist, quit now. */
 186                 if (stat(target, &sb)) {
 187                         warn("%s", target);
 188                         return (1);
 189                 }
 190                 /* Only symbolic links to directories. */
 191                 if (S_ISDIR(sb.st_mode)) {
 192                         errno = EISDIR;
 193                         warn("%s", target);
 194                         return (1);
 195                 }
 196         }
 197
 198         /*
 199          * If the source is a directory (and not a symlink if hflag),
 200          * append the target's name.
 201          */
 202         if (isdir ||
 203             (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
 204             (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
 205                 if (strlcpy(bbuf, target, sizeof(bbuf)) >= sizeof(bbuf) ||
 206                     (p = basename(bbuf)) == NULL ||
 207                     snprintf(path, sizeof(path), "%s/%s", source, p) >=
 208                     (ssize_t)sizeof(path)) {
 209                         errno = ENAMETOOLONG;
 210                         warn("%s", target);
 211                         return (1);
 212                 }
 213                 source = path;
 214         }
 215
 216         exists = !lstat(source, &sb);
 217         /*
 218          * If the file exists, then unlink it forcibly if -f was specified
 219          * and interactively if -i was specified.
 220          */
 221         if (fflag && exists) {
 222                 if (Fflag && S_ISDIR(sb.st_mode)) {
 223                         if (rmdir(source)) {
 224                                 warn("%s", source);
 225                                 return (1);
 226                         }
 227                 } else if (unlink(source)) {
 228                         warn("%s", source);
 229                         return (1);
 230                 }
 231         } else if (iflag && exists) {
 232                 fflush(stdout);
 233                 fprintf(stderr, "replace %s? ", source);
 234
 235                 first = ch = getchar();
 236                 while(ch != '\n' && ch != EOF)
 237                         ch = getchar();
 238                 if (first != 'y' && first != 'Y') {
 239                         fprintf(stderr, "not replaced\n");
 240                         return (1);
 241                 }
 242
 243                 if (Fflag && S_ISDIR(sb.st_mode)) {
 244                         if (rmdir(source)) {
 245                                 warn("%s", source);
 246                                 return (1);
 247                         }
 248                 } else if (unlink(source)) {
 249                         warn("%s", source);
 250                         return (1);
 251                 }
 252         }
 253
 254         /* Attempt the link. */
 255         if ((*linkf)(target, source)) {
 256                 warn("%s", source);
 257                 return (1);
 258         }
 259         if (vflag)
 260                 (void)printf("%s %c> %s\n", source, linkch, target);
 261         return (0);
 262 }
 263
 264 void
 265 usage(void)
 266 {
 267         (void)fprintf(stderr, "%s\n%s\n%s\n",
 268             "usage: ln [-Ffhinsv] source_file [target_file]",
 269             "       ln [-Ffhinsv] source_file ... target_dir",
 270             "       link source_file target_file");
 271         exit(1);
 272 }