1 /* `ln' program to create links between files.
2 Copyright (C) 86, 89, 90, 91, 1995-2003 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
18 /* Written by Mike Parker and David MacKenzie. */
22 #include <sys/types.h>
27 #include "backupfile.h"
32 /* The official name of this program (e.g., no `g' prefix). */
33 #define PROGRAM_NAME "ln"
35 #define AUTHORS N_ ("Mike Parker and David MacKenzie")
37 #ifndef ENABLE_HARD_LINK_TO_SYMLINK_WARNING
38 # define ENABLE_HARD_LINK_TO_SYMLINK_WARNING 0
41 /* For long options that have no equivalent short option, use a
42 non-character as a pseudo short option, starting with CHAR_MAX + 1. */
45 TARGET_DIRECTORY_OPTION = CHAR_MAX + 1
48 int link (); /* Some systems don't declare this anywhere. */
54 /* In being careful not even to try to make hard links to directories,
55 we have to know whether link(2) follows symlinks. If it does, then
56 we have to *stat* the `source' to see if the resulting link would be
57 to a directory. Otherwise, we have to use *lstat* so that we allow
58 users to make hard links to symlinks-that-point-to-directories. */
60 #if LINK_FOLLOWS_SYMLINKS
61 # define STAT_LIKE_LINK(File, Stat_buf) \
64 # define STAT_LIKE_LINK(File, Stat_buf) \
65 lstat (File, Stat_buf)
68 /* Construct a string NEW_DEST by concatenating DEST, a slash, and
69 basename(SOURCE) in alloca'd memory. Don't modify DEST or SOURCE. */
71 #define PATH_BASENAME_CONCAT(new_dest, dest, source) \
74 const char *source_base; \
77 tmp_source = (char *) alloca (strlen ((source)) + 1); \
78 strcpy (tmp_source, (source)); \
79 strip_trailing_slashes (tmp_source); \
80 source_base = base_name (tmp_source); \
82 (new_dest) = (char *) alloca (strlen ((dest)) + 1 \
83 + strlen (source_base) + 1); \
84 stpcpy (stpcpy (stpcpy ((new_dest), (dest)), "/"), source_base);\
91 /* The name by which the program was run, for error messages. */
95 enum backup_type backup_type;
97 /* A pointer to the function used to make links. This will point to either
98 `link' or `symlink'. */
99 static int (*linkfunc) ();
101 /* If nonzero, make symbolic links; otherwise, make hard links. */
102 static int symbolic_link;
104 /* If nonzero, ask the user before removing existing files. */
105 static int interactive;
107 /* If nonzero, remove existing files unconditionally. */
108 static int remove_existing_files;
110 /* If nonzero, list each file as it is moved. */
113 /* If nonzero, allow the superuser to make hard links to directories. */
114 static int hard_dir_link;
116 /* If nonzero, and the specified destination is a symbolic link to a
117 directory, treat it just as if it were a directory. Otherwise, the
118 command `ln --force --no-dereference file symlink-to-dir' deletes
119 symlink-to-dir before creating the new link. */
120 static int dereference_dest_dir_symlinks = 1;
122 static struct option const long_options[] =
124 {"backup", optional_argument, NULL, 'b'},
125 {"directory", no_argument, NULL, 'F'},
126 {"no-dereference", no_argument, NULL, 'n'},
127 {"force", no_argument, NULL, 'f'},
128 {"interactive", no_argument, NULL, 'i'},
129 {"suffix", required_argument, NULL, 'S'},
130 {"target-directory", required_argument, NULL, TARGET_DIRECTORY_OPTION},
131 {"symbolic", no_argument, NULL, 's'},
132 {"verbose", no_argument, NULL, 'v'},
133 {"version-control", required_argument, NULL, 'V'}, /* Deprecated. FIXME. */
134 {GETOPT_HELP_OPTION_DECL},
135 {GETOPT_VERSION_OPTION_DECL},
139 /* Make a link DEST to the (usually) existing file SOURCE.
140 Symbolic links to nonexistent files are allowed.
141 If DEST is a directory, put the link to SOURCE in that directory.
142 Return 1 if there is an error, otherwise 0. */
145 do_link (const char *source, const char *dest)
147 struct stat source_stats;
148 struct stat dest_stats;
149 char *dest_backup = NULL;
151 int backup_succeeded = 0;
153 /* Use stat here instead of lstat.
154 On SVR4, link does not follow symlinks, so this check disallows
155 making hard links to symlinks that point to directories. Big deal.
156 On other systems, link follows symlinks, so this check is right. */
159 if (STAT_LIKE_LINK (source, &source_stats) != 0)
161 error (0, errno, _("accessing %s"), quote (source));
165 if (ENABLE_HARD_LINK_TO_SYMLINK_WARNING
166 && S_ISLNK (source_stats.st_mode))
168 error (0, 0, _("%s: warning: making a hard link to a symbolic link\
173 if (!hard_dir_link && S_ISDIR (source_stats.st_mode))
175 error (0, 0, _("%s: hard link not allowed for directory"),
181 lstat_status = lstat (dest, &dest_stats);
182 if (lstat_status != 0 && errno != ENOENT)
184 error (0, errno, _("accessing %s"), quote (dest));
188 /* If the destination is a directory or (it is a symlink to a directory
189 and the user has not specified --no-dereference), then form the
190 actual destination name by appending base_name (source) to the
191 specified destination directory. */
192 if ((lstat_status == 0
193 && S_ISDIR (dest_stats.st_mode))
195 || (dereference_dest_dir_symlinks
196 && (lstat_status == 0
197 && S_ISLNK (dest_stats.st_mode)
202 /* Target is a directory; build the full filename. */
204 PATH_BASENAME_CONCAT (new_dest, dest, source);
207 /* Get stats for new DEST. */
208 lstat_status = lstat (dest, &dest_stats);
209 if (lstat_status != 0 && errno != ENOENT)
211 error (0, errno, _("accessing %s"), quote (dest));
216 /* If --force (-f) has been specified without --backup, then before
217 making a link ln must remove the destination file if it exists.
218 (with --backup, it just renames any existing destination file)
219 But if the source and destination are the same, don't remove
220 anything and fail right here. */
221 if (remove_existing_files
223 /* Allow `ln -sf --backup k k' to succeed in creating the
224 self-referential symlink, but don't allow the hard-linking
225 equivalent: `ln -f k k' (with or without --backup) to get
226 beyond this point, because the error message you'd get is
228 && (backup_type == none || !symbolic_link)
229 && (!symbolic_link || stat (source, &source_stats) == 0)
230 && source_stats.st_dev == dest_stats.st_dev
231 && source_stats.st_ino == dest_stats.st_ino
232 /* The following detects whether removing DEST will also remove
233 SOURCE. If the file has only one link then both are surely
234 the same link. Otherwise check whether they point to the same
235 name in the same directory. */
236 && (source_stats.st_nlink == 1 || same_name (source, dest)))
238 error (0, 0, _("%s and %s are the same file"),
239 quote_n (0, source), quote_n (1, dest));
243 if (lstat_status == 0 || lstat (dest, &dest_stats) == 0)
245 if (S_ISDIR (dest_stats.st_mode))
247 error (0, 0, _("%s: cannot overwrite directory"), quote (dest));
252 fprintf (stderr, _("%s: replace %s? "), program_name, quote (dest));
256 else if (!remove_existing_files && backup_type == none)
258 error (0, 0, _("%s: File exists"), quote (dest));
262 if (backup_type != none)
264 char *tmp_backup = find_backup_file_name (dest, backup_type);
265 if (tmp_backup == NULL)
267 dest_backup = (char *) alloca (strlen (tmp_backup) + 1);
268 strcpy (dest_backup, tmp_backup);
270 if (rename (dest, dest_backup))
274 error (0, errno, _("cannot backup %s"), quote (dest));
282 backup_succeeded = 1;
286 /* Try to unlink DEST even if we may have renamed it. In some unusual
287 cases (when DEST and DEST_BACKUP are hard-links that refer to the
288 same file), rename succeeds and DEST remains. If we didn't remove
289 DEST in that case, the subsequent LINKFUNC call would fail. */
290 if (unlink (dest) && errno != ENOENT)
292 error (0, errno, _("cannot remove %s"), quote (dest));
296 else if (errno != ENOENT)
298 error (0, errno, _("accessing %s"), quote (dest));
304 printf ((symbolic_link
305 ? _("create symbolic link %s to %s")
306 : _("create hard link %s to %s")),
307 quote_n (0, dest), quote_n (1, source));
308 if (backup_succeeded)
309 printf (_(" (backup: %s)"), quote (dest_backup));
313 if ((*linkfunc) (source, dest) == 0)
320 ? _("creating symbolic link %s to %s")
321 : _("creating hard link %s to %s")),
322 quote_n (0, dest), quote_n (1, source));
326 if (rename (dest_backup, dest))
327 error (0, errno, _("cannot un-backup %s"), quote (dest));
336 fprintf (stderr, _("Try `%s --help' for more information.\n"),
341 Usage: %s [OPTION]... TARGET [LINK_NAME]\n\
342 or: %s [OPTION]... TARGET... DIRECTORY\n\
343 or: %s [OPTION]... --target-directory=DIRECTORY TARGET...\n\
345 program_name, program_name, program_name);
347 Create a link to the specified TARGET with optional LINK_NAME.\n\
348 If LINK_NAME is omitted, a link with the same basename as the TARGET is\n\
349 created in the current directory. When using the second form with more\n\
350 than one TARGET, the last argument must be a directory; create links\n\
351 in DIRECTORY to each TARGET. Create hard links by default, symbolic\n\
352 links with --symbolic. When creating hard links, each TARGET must exist.\n\
356 Mandatory arguments to long options are mandatory for short options too.\n\
359 --backup[=CONTROL] make a backup of each existing destination file\n\
360 -b like --backup but does not accept an argument\n\
361 -d, -F, --directory hard link directories (super-user only)\n\
362 -f, --force remove existing destination files\n\
365 -n, --no-dereference treat destination that is a symlink to a\n\
366 directory as if it were a normal file\n\
367 -i, --interactive prompt whether to remove destinations\n\
368 -s, --symbolic make symbolic links instead of hard links\n\
371 -S, --suffix=SUFFIX override the usual backup suffix\n\
372 --target-directory=DIRECTORY specify the DIRECTORY in which to create\n\
374 -v, --verbose print name of each file before linking\n\
376 fputs (HELP_OPTION_DESCRIPTION, stdout);
377 fputs (VERSION_OPTION_DESCRIPTION, stdout);
380 The backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.\n\
381 The version control method may be selected via the --backup option or through\n\
382 the VERSION_CONTROL environment variable. Here are the values:\n\
386 none, off never make backups (even if --backup is given)\n\
387 numbered, t make numbered backups\n\
388 existing, nil numbered if numbered backups exist, simple otherwise\n\
389 simple, never always make simple backups\n\
391 printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
397 main (int argc, char **argv)
401 int make_backups = 0;
402 char *backup_suffix_string;
403 char *version_control_string = NULL;
404 char *target_directory = NULL;
405 int target_directory_specified;
406 unsigned int n_files;
410 initialize_main (&argc, &argv);
411 program_name = argv[0];
412 setlocale (LC_ALL, "");
413 bindtextdomain (PACKAGE, LOCALEDIR);
414 textdomain (PACKAGE);
416 atexit (close_stdout);
418 /* FIXME: consider not calling getenv for SIMPLE_BACKUP_SUFFIX unless
419 we'll actually use backup_suffix_string. */
420 backup_suffix_string = getenv ("SIMPLE_BACKUP_SUFFIX");
422 symbolic_link = remove_existing_files = interactive = verbose
426 while ((c = getopt_long (argc, argv, "bdfinsvFS:V:", long_options, NULL))
431 case 0: /* Long-named option. */
434 case 'V': /* FIXME: this is deprecated. Remove it in 2001. */
436 _("warning: --version-control (-V) is obsolete; support for\
437 it\nwill be removed in some future release. Use --backup=%s instead."
444 version_control_string = optarg;
451 remove_existing_files = 1;
455 remove_existing_files = 0;
459 dereference_dest_dir_symlinks = 0;
465 error (EXIT_FAILURE, 0,
466 _("symbolic links are not supported on this system"));
469 case TARGET_DIRECTORY_OPTION:
470 target_directory = optarg;
477 backup_suffix_string = optarg;
479 case_GETOPT_HELP_CHAR;
480 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
482 usage (EXIT_FAILURE);
489 error (0, 0, _("missing file argument"));
490 usage (EXIT_FAILURE);
493 n_files = argc - optind;
494 file = argv + optind;
496 target_directory_specified = (target_directory != NULL);
497 if (!target_directory)
498 target_directory = file[n_files - 1];
500 /* If target directory is not specified, and there's only one
501 file argument, then pretend `.' was given as the second argument. */
502 if (!target_directory_specified && n_files == 1)
504 static char *dummy[2];
513 dest_is_dir = isdir (target_directory);
521 if (target_directory_specified && !dest_is_dir)
523 error (0, 0, _("%s: specified target directory is not a directory"),
524 quote (target_directory));
525 usage (EXIT_FAILURE);
528 if (backup_suffix_string)
529 simple_backup_suffix = xstrdup (backup_suffix_string);
531 backup_type = (make_backups
532 ? xget_version (_("backup type"), version_control_string)
535 if (target_directory_specified || n_files > 2)
538 unsigned int last_file_idx = (target_directory_specified
542 if (!target_directory_specified && !dest_is_dir)
543 error (EXIT_FAILURE, 0,
544 _("when making multiple links, last argument must be a directory"));
545 for (i = 0; i <= last_file_idx; ++i)
546 errors += do_link (file[i], target_directory);
550 struct stat source_stats;
558 /* When the destination is specified with a trailing slash and the
559 source exists but is not a directory, convert the user's command
560 `ln source dest/' to `ln source dest/basename(source)'. */
562 if (dest[strlen (dest) - 1] == '/'
563 && lstat (source, &source_stats) == 0
564 && !S_ISDIR (source_stats.st_mode))
566 PATH_BASENAME_CONCAT (new_dest, dest, source);
573 errors = do_link (source, new_dest);