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 WRITTEN_BY _("Written by 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; \
76 size_t buf_len = strlen (source) + 1; \
78 tmp_source = (char *) alloca (buf_len); \
79 memcpy (tmp_source, (source), buf_len); \
80 strip_trailing_slashes (tmp_source); \
81 source_base = base_name (tmp_source); \
83 (new_dest) = (char *) alloca (strlen ((dest)) + 1 \
84 + strlen (source_base) + 1); \
85 stpcpy (stpcpy (stpcpy ((new_dest), (dest)), "/"), source_base);\
92 /* The name by which the program was run, for error messages. */
96 enum backup_type backup_type;
98 /* A pointer to the function used to make links. This will point to either
99 `link' or `symlink'. */
100 static int (*linkfunc) ();
102 /* If nonzero, make symbolic links; otherwise, make hard links. */
103 static int symbolic_link;
105 /* If nonzero, ask the user before removing existing files. */
106 static int interactive;
108 /* If nonzero, remove existing files unconditionally. */
109 static int remove_existing_files;
111 /* If nonzero, list each file as it is moved. */
114 /* If nonzero, allow the superuser to make hard links to directories. */
115 static int hard_dir_link;
117 /* If nonzero, and the specified destination is a symbolic link to a
118 directory, treat it just as if it were a directory. Otherwise, the
119 command `ln --force --no-dereference file symlink-to-dir' deletes
120 symlink-to-dir before creating the new link. */
121 static int dereference_dest_dir_symlinks = 1;
123 static struct option const long_options[] =
125 {"backup", optional_argument, NULL, 'b'},
126 {"directory", no_argument, NULL, 'F'},
127 {"no-dereference", no_argument, NULL, 'n'},
128 {"force", no_argument, NULL, 'f'},
129 {"interactive", no_argument, NULL, 'i'},
130 {"suffix", required_argument, NULL, 'S'},
131 {"target-directory", required_argument, NULL, TARGET_DIRECTORY_OPTION},
132 {"symbolic", no_argument, NULL, 's'},
133 {"verbose", no_argument, NULL, 'v'},
134 {"version-control", required_argument, NULL, 'V'}, /* Deprecated. FIXME. */
135 {GETOPT_HELP_OPTION_DECL},
136 {GETOPT_VERSION_OPTION_DECL},
140 /* Make a link DEST to the (usually) existing file SOURCE.
141 Symbolic links to nonexistent files are allowed.
142 If DEST is a directory, put the link to SOURCE in that directory.
143 Return 1 if there is an error, otherwise 0. */
146 do_link (const char *source, const char *dest)
148 struct stat source_stats;
149 struct stat dest_stats;
150 char *dest_backup = NULL;
152 int backup_succeeded = 0;
154 /* Use stat here instead of lstat.
155 On SVR4, link does not follow symlinks, so this check disallows
156 making hard links to symlinks that point to directories. Big deal.
157 On other systems, link follows symlinks, so this check is right. */
160 if (STAT_LIKE_LINK (source, &source_stats) != 0)
162 error (0, errno, _("accessing %s"), quote (source));
166 if (ENABLE_HARD_LINK_TO_SYMLINK_WARNING
167 && S_ISLNK (source_stats.st_mode))
169 error (0, 0, _("%s: warning: making a hard link to a symbolic link\
174 if (!hard_dir_link && S_ISDIR (source_stats.st_mode))
176 error (0, 0, _("%s: hard link not allowed for directory"),
182 lstat_status = lstat (dest, &dest_stats);
183 if (lstat_status != 0 && errno != ENOENT)
185 error (0, errno, _("accessing %s"), quote (dest));
189 /* If the destination is a directory or (it is a symlink to a directory
190 and the user has not specified --no-dereference), then form the
191 actual destination name by appending base_name (source) to the
192 specified destination directory. */
193 if ((lstat_status == 0
194 && S_ISDIR (dest_stats.st_mode))
196 || (dereference_dest_dir_symlinks
197 && (lstat_status == 0
198 && S_ISLNK (dest_stats.st_mode)
203 /* Target is a directory; build the full filename. */
205 PATH_BASENAME_CONCAT (new_dest, dest, source);
208 /* Get stats for new DEST. */
209 lstat_status = lstat (dest, &dest_stats);
210 if (lstat_status != 0 && errno != ENOENT)
212 error (0, errno, _("accessing %s"), quote (dest));
217 /* If --force (-f) has been specified without --backup, then before
218 making a link ln must remove the destination file if it exists.
219 (with --backup, it just renames any existing destination file)
220 But if the source and destination are the same, don't remove
221 anything and fail right here. */
222 if (remove_existing_files
224 /* Allow `ln -sf --backup k k' to succeed in creating the
225 self-referential symlink, but don't allow the hard-linking
226 equivalent: `ln -f k k' (with or without --backup) to get
227 beyond this point, because the error message you'd get is
229 && (backup_type == none || !symbolic_link)
230 && (!symbolic_link || stat (source, &source_stats) == 0)
231 && SAME_INODE (source_stats, dest_stats)
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)
265 char *tmp_backup = find_backup_file_name (dest, backup_type);
266 if (tmp_backup == NULL)
268 buf_len = strlen (tmp_backup) + 1;
269 dest_backup = (char *) alloca (buf_len);
270 memcpy (dest_backup, tmp_backup, buf_len);
272 if (rename (dest, dest_backup))
276 error (0, errno, _("cannot backup %s"), quote (dest));
284 backup_succeeded = 1;
288 /* Try to unlink DEST even if we may have renamed it. In some unusual
289 cases (when DEST and DEST_BACKUP are hard-links that refer to the
290 same file), rename succeeds and DEST remains. If we didn't remove
291 DEST in that case, the subsequent LINKFUNC call would fail. */
292 if (unlink (dest) && errno != ENOENT)
294 error (0, errno, _("cannot remove %s"), quote (dest));
298 else if (errno != ENOENT)
300 error (0, errno, _("accessing %s"), quote (dest));
306 printf ((symbolic_link
307 ? _("create symbolic link %s to %s")
308 : _("create hard link %s to %s")),
309 quote_n (0, dest), quote_n (1, source));
310 if (backup_succeeded)
311 printf (_(" (backup: %s)"), quote (dest_backup));
315 if ((*linkfunc) (source, dest) == 0)
322 ? _("creating symbolic link %s to %s")
323 : _("creating hard link %s to %s")),
324 quote_n (0, dest), quote_n (1, source));
328 if (rename (dest_backup, dest))
329 error (0, errno, _("cannot un-backup %s"), quote (dest));
338 fprintf (stderr, _("Try `%s --help' for more information.\n"),
343 Usage: %s [OPTION]... TARGET [LINK_NAME]\n\
344 or: %s [OPTION]... TARGET... DIRECTORY\n\
345 or: %s [OPTION]... --target-directory=DIRECTORY TARGET...\n\
347 program_name, program_name, program_name);
349 Create a link to the specified TARGET with optional LINK_NAME.\n\
350 If LINK_NAME is omitted, a link with the same basename as the TARGET is\n\
351 created in the current directory. When using the second form with more\n\
352 than one TARGET, the last argument must be a directory; create links\n\
353 in DIRECTORY to each TARGET. Create hard links by default, symbolic\n\
354 links with --symbolic. When creating hard links, each TARGET must exist.\n\
358 Mandatory arguments to long options are mandatory for short options too.\n\
361 --backup[=CONTROL] make a backup of each existing destination file\n\
362 -b like --backup but does not accept an argument\n\
363 -d, -F, --directory hard link directories (super-user only)\n\
364 -f, --force remove existing destination files\n\
367 -n, --no-dereference treat destination that is a symlink to a\n\
368 directory as if it were a normal file\n\
369 -i, --interactive prompt whether to remove destinations\n\
370 -s, --symbolic make symbolic links instead of hard links\n\
373 -S, --suffix=SUFFIX override the usual backup suffix\n\
374 --target-directory=DIRECTORY specify the DIRECTORY in which to create\n\
376 -v, --verbose print name of each file before linking\n\
378 fputs (HELP_OPTION_DESCRIPTION, stdout);
379 fputs (VERSION_OPTION_DESCRIPTION, stdout);
382 The backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.\n\
383 The version control method may be selected via the --backup option or through\n\
384 the VERSION_CONTROL environment variable. Here are the values:\n\
388 none, off never make backups (even if --backup is given)\n\
389 numbered, t make numbered backups\n\
390 existing, nil numbered if numbered backups exist, simple otherwise\n\
391 simple, never always make simple backups\n\
393 printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
399 main (int argc, char **argv)
403 int make_backups = 0;
404 char *backup_suffix_string;
405 char *version_control_string = NULL;
406 char *target_directory = NULL;
407 int target_directory_specified;
408 unsigned int n_files;
412 initialize_main (&argc, &argv);
413 program_name = argv[0];
414 setlocale (LC_ALL, "");
415 bindtextdomain (PACKAGE, LOCALEDIR);
416 textdomain (PACKAGE);
418 atexit (close_stdout);
420 /* FIXME: consider not calling getenv for SIMPLE_BACKUP_SUFFIX unless
421 we'll actually use backup_suffix_string. */
422 backup_suffix_string = getenv ("SIMPLE_BACKUP_SUFFIX");
424 symbolic_link = remove_existing_files = interactive = verbose
428 while ((c = getopt_long (argc, argv, "bdfinsvFS:V:", long_options, NULL))
433 case 0: /* Long-named option. */
436 case 'V': /* FIXME: this is deprecated. Remove it in 2001. */
438 _("warning: --version-control (-V) is obsolete; support for\
439 it\nwill be removed in some future release. Use --backup=%s instead."
446 version_control_string = optarg;
453 remove_existing_files = 1;
457 remove_existing_files = 0;
461 dereference_dest_dir_symlinks = 0;
467 error (EXIT_FAILURE, 0,
468 _("symbolic links are not supported on this system"));
471 case TARGET_DIRECTORY_OPTION:
472 target_directory = optarg;
479 backup_suffix_string = optarg;
481 case_GETOPT_HELP_CHAR;
482 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, WRITTEN_BY);
484 usage (EXIT_FAILURE);
491 error (0, 0, _("missing file argument"));
492 usage (EXIT_FAILURE);
495 n_files = argc - optind;
496 file = argv + optind;
498 target_directory_specified = (target_directory != NULL);
499 if (!target_directory)
500 target_directory = file[n_files - 1];
502 /* If target directory is not specified, and there's only one
503 file argument, then pretend `.' was given as the second argument. */
504 if (!target_directory_specified && n_files == 1)
506 static char *dummy[2];
515 dest_is_dir = isdir (target_directory);
523 if (target_directory_specified && !dest_is_dir)
525 error (0, 0, _("%s: specified target directory is not a directory"),
526 quote (target_directory));
527 usage (EXIT_FAILURE);
530 if (backup_suffix_string)
531 simple_backup_suffix = xstrdup (backup_suffix_string);
533 backup_type = (make_backups
534 ? xget_version (_("backup type"), version_control_string)
537 if (target_directory_specified || n_files > 2)
540 unsigned int last_file_idx = (target_directory_specified
544 if (!target_directory_specified && !dest_is_dir)
545 error (EXIT_FAILURE, 0,
546 _("when making multiple links, last argument must be a directory"));
547 for (i = 0; i <= last_file_idx; ++i)
548 errors += do_link (file[i], target_directory);
552 struct stat source_stats;
560 /* When the destination is specified with a trailing slash and the
561 source exists but is not a directory, convert the user's command
562 `ln source dest/' to `ln source dest/basename(source)'. */
564 if (dest[strlen (dest) - 1] == '/'
565 && lstat (source, &source_stats) == 0
566 && !S_ISDIR (source_stats.st_mode))
568 PATH_BASENAME_CONCAT (new_dest, dest, source);
575 errors = do_link (source, new_dest);