1 /* `ln' program to create links between files.
2 Copyright (C) 86, 89, 90, 91, 1995-2000 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. */
26 #include <sys/types.h>
31 #include "backupfile.h"
34 /* The official name of this program (e.g., no `g' prefix). */
35 #define PROGRAM_NAME "ln"
37 #define AUTHORS "Mike Parker and David MacKenzie"
39 /* For long options that have no equivalent short option, use a
40 non-character as a pseudo short option, starting with CHAR_MAX + 1. */
43 TARGET_DIRECTORY_OPTION = CHAR_MAX + 1
46 int link (); /* Some systems don't declare this anywhere. */
52 /* In being careful not even to try to make hard links to directories,
53 we have to know whether link(2) follows symlinks. If it does, then
54 we have to *stat* the `source' to see if the resulting link would be
55 to a directory. Otherwise, we have to use *lstat* so that we allow
56 users to make hard links to symlinks-that-point-to-directories. */
58 #if LINK_FOLLOWS_SYMLINKS
59 # define STAT_LIKE_LINK(File, Stat_buf) \
62 # define STAT_LIKE_LINK(File, Stat_buf) \
63 lstat (File, Stat_buf)
66 /* Construct a string NEW_DEST by concatenating DEST, a slash, and
67 basename(SOURCE) in alloca'd memory. Don't modify DEST or SOURCE. */
69 #define PATH_BASENAME_CONCAT(new_dest, dest, source) \
72 const char *source_base; \
75 tmp_source = (char *) alloca (strlen ((source)) + 1); \
76 strcpy (tmp_source, (source)); \
77 strip_trailing_slashes (tmp_source); \
78 source_base = base_name (tmp_source); \
80 (new_dest) = (char *) alloca (strlen ((dest)) + 1 \
81 + strlen (source_base) + 1); \
82 stpcpy (stpcpy (stpcpy ((new_dest), (dest)), "/"), source_base);\
88 void strip_trailing_slashes ();
90 /* The name by which the program was run, for error messages. */
94 enum backup_type backup_type;
96 /* A pointer to the function used to make links. This will point to either
97 `link' or `symlink'. */
98 static int (*linkfunc) ();
100 /* If nonzero, make symbolic links; otherwise, make hard links. */
101 static int symbolic_link;
103 /* If nonzero, ask the user before removing existing files. */
104 static int interactive;
106 /* If nonzero, remove existing files unconditionally. */
107 static int remove_existing_files;
109 /* If nonzero, list each file as it is moved. */
112 /* If nonzero, allow the superuser to make hard links to directories. */
113 static int hard_dir_link;
115 /* If nonzero, and the specified destination is a symbolic link to a
116 directory, treat it just as if it were a directory. Otherwise, the
117 command `ln --force --no-dereference file symlink-to-dir' deletes
118 symlink-to-dir before creating the new link. */
119 static int dereference_dest_dir_symlinks = 1;
121 static struct option const long_options[] =
123 {"backup", optional_argument, NULL, 'b'},
124 {"directory", no_argument, NULL, 'F'},
125 {"no-dereference", no_argument, NULL, 'n'},
126 {"force", no_argument, NULL, 'f'},
127 {"interactive", no_argument, NULL, 'i'},
128 {"suffix", required_argument, NULL, 'S'},
129 {"target-directory", required_argument, NULL, TARGET_DIRECTORY_OPTION},
130 {"symbolic", no_argument, NULL, 's'},
131 {"verbose", no_argument, NULL, 'v'},
132 {"version-control", required_argument, NULL, 'V'}, /* Deprecated. FIXME. */
133 {GETOPT_HELP_OPTION_DECL},
134 {GETOPT_VERSION_OPTION_DECL},
138 /* Make a link DEST to the (usually) existing file SOURCE.
139 Symbolic links to nonexistent files are allowed.
140 If DEST is a directory, put the link to SOURCE in that directory.
141 Return 1 if there is an error, otherwise 0. */
144 do_link (const char *source, const char *dest)
146 struct stat source_stats;
147 struct stat dest_stats;
148 char *dest_backup = NULL;
150 int backup_succeeded = 0;
152 /* Use stat here instead of lstat.
153 On SVR4, link does not follow symlinks, so this check disallows
154 making hard links to symlinks that point to directories. Big deal.
155 On other systems, link follows symlinks, so this check is right. */
158 if (STAT_LIKE_LINK (source, &source_stats) != 0)
160 error (0, errno, "%s", source);
164 if (S_ISLNK (source_stats.st_mode))
166 error (0, 0, _("%s: warning: making a hard link to a symbolic link\
171 if (!hard_dir_link && S_ISDIR (source_stats.st_mode))
173 error (0, 0, _("%s: hard link not allowed for directory"), source);
178 lstat_status = lstat (dest, &dest_stats);
179 if (lstat_status != 0 && errno != ENOENT)
181 error (0, errno, "%s", dest);
185 /* If the destination is a directory or (it is a symlink to a directory
186 and the user has not specified --no-dereference), then form the
187 actual destination name by appending base_name (source) to the
188 specified destination directory. */
189 if ((lstat_status == 0
190 && S_ISDIR (dest_stats.st_mode))
192 || (dereference_dest_dir_symlinks
193 && (lstat_status == 0
194 && S_ISLNK (dest_stats.st_mode)
199 /* Target is a directory; build the full filename. */
201 PATH_BASENAME_CONCAT (new_dest, dest, source);
204 /* Get stats for new DEST. */
205 lstat_status = lstat (dest, &dest_stats);
206 if (lstat_status != 0 && errno != ENOENT)
208 error (0, errno, "%s", dest);
213 /* If --force (-f) has been specified without --backup, then before
214 making a link ln must remove the destination file if it exists.
215 (with --backup, it just renames any existing destination file)
216 But if the source and destination are the same, don't remove
217 anything and fail right here. */
218 if (remove_existing_files
220 /* Allow `ln -sf --backup k k' to succeed in creating the
221 self-referential symlink, but don't allow the hard-linking
222 equivalent: `ln -f k k' (with or without --backup) to get
223 beyond this point, because the error message you'd get is
225 && (backup_type == none || !symlink)
226 && (!symbolic_link || stat (source, &source_stats) == 0)
227 && source_stats.st_dev == dest_stats.st_dev
228 && source_stats.st_ino == dest_stats.st_ino
229 /* The following detects whether removing DEST will also remove
230 SOURCE. If the file has only one link then both are surely
231 the same link. Otherwise check whether they point to the same
232 name in the same directory. */
233 && (source_stats.st_nlink == 1 || same_name (source, dest)))
235 error (0, 0, _("`%s' and `%s' are the same file"), source, dest);
239 if (lstat_status == 0 || lstat (dest, &dest_stats) == 0)
241 if (S_ISDIR (dest_stats.st_mode))
243 error (0, 0, _("%s: cannot overwrite directory"), dest);
248 fprintf (stderr, _("%s: replace `%s'? "), program_name, dest);
252 else if (!remove_existing_files && backup_type == none)
254 error (0, 0, _("%s: File exists"), dest);
258 if (backup_type != none)
260 char *tmp_backup = find_backup_file_name (dest, backup_type);
261 if (tmp_backup == NULL)
262 error (1, 0, _("virtual memory exhausted"));
263 dest_backup = (char *) alloca (strlen (tmp_backup) + 1);
264 strcpy (dest_backup, tmp_backup);
266 if (rename (dest, dest_backup))
270 error (0, errno, _("cannot backup `%s'"), dest);
278 backup_succeeded = 1;
282 /* Try to unlink DEST even if we may have renamed it. In some unusual
283 cases (when DEST and DEST_BACKUP are hard-links that refer to the
284 same file), rename succeeds and DEST remains. If we didn't remove
285 DEST in that case, the subsequent LINKFUNC call would fail. */
286 if (unlink (dest) && errno != ENOENT)
288 error (0, errno, _("cannot remove `%s'"), dest);
292 else if (errno != ENOENT)
294 error (0, errno, "%s", dest);
300 printf ((symbolic_link
301 ? _("create symbolic link `%s' to `%s'")
302 : _("create hard link `%s' to `%s'")),
304 if (backup_succeeded)
305 printf (_(" (backup: %s)"), dest_backup);
309 if ((*linkfunc) (source, dest) == 0)
316 ? _("create symbolic link `%s' to `%s'")
317 : _("create hard link `%s' to `%s'")),
322 if (rename (dest_backup, dest))
323 error (0, errno, _("cannot un-backup `%s'"), dest);
332 fprintf (stderr, _("Try `%s --help' for more information.\n"),
337 Usage: %s [OPTION]... TARGET [LINK_NAME]\n\
338 or: %s [OPTION]... TARGET... DIRECTORY\n\
339 or: %s [OPTION]... --target-directory=DIRECTORY TARGET...\n\
341 program_name, program_name, program_name);
343 Create a link to the specified TARGET with optional LINK_NAME.\n\
344 If LINK_NAME is omitted, a link with the same basename as the TARGET is\n\
345 created in the current directory. When using the second form with more\n\
346 than one TARGET, the last argument must be a directory; create links\n\
347 in DIRECTORY to each TARGET. Create hard links by default, symbolic\n\
348 links with --symbolic. When creating hard links, each TARGET must exist.\n\
350 --backup[=CONTROL] make a backup of each existing destination file\n\
351 -b like --backup but does not accept an argument\n\
352 -d, -F, --directory hard link directories (super-user only)\n\
353 -f, --force remove existing destination files\n\
354 -n, --no-dereference treat destination that is a symlink to a\n\
355 directory as if it were a normal file\n\
356 -i, --interactive prompt whether to remove destinations\n\
357 -s, --symbolic make symbolic links instead of hard links\n\
358 -S, --suffix=SUFFIX override the usual backup suffix\n\
359 --target-directory=DIRECTORY specify the DIRECTORY in which to create\n\
361 -v, --verbose print name of each file before linking\n\
362 --help display this help and exit\n\
363 --version output version information and exit\n\
367 The backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.\n\
368 The version control method may be selected via the --backup option or through\n\
369 the VERSION_CONTROL environment variable. Here are the values:\n\
371 none, off never make backups (even if --backup is given)\n\
372 numbered, t make numbered backups\n\
373 existing, nil numbered if numbered backups exist, simple otherwise\n\
374 simple, never always make simple backups\n\
376 puts (_("\nReport bugs to <bug-fileutils@gnu.org>."));
382 main (int argc, char **argv)
386 int make_backups = 0;
387 char *backup_suffix_string;
388 char *version_control_string = NULL;
389 char *target_directory = NULL;
390 int target_directory_specified;
391 unsigned int n_files;
395 program_name = argv[0];
396 setlocale (LC_ALL, "");
397 bindtextdomain (PACKAGE, LOCALEDIR);
398 textdomain (PACKAGE);
400 atexit (close_stdout);
402 /* FIXME: consider not calling getenv for SIMPLE_BACKUP_SUFFIX unless
403 we'll actually use backup_suffix_string. */
404 backup_suffix_string = getenv ("SIMPLE_BACKUP_SUFFIX");
406 symbolic_link = remove_existing_files = interactive = verbose
410 while ((c = getopt_long (argc, argv, "bdfinsvFS:V:", long_options, NULL))
415 case 0: /* Long-named option. */
418 case 'V': /* FIXME: this is deprecated. Remove it in 2001. */
420 _("warning: --version-control (-V) is obsolete; support for\
421 it\nwill be removed in some future release. Use --backup=%s instead."
428 version_control_string = optarg;
435 remove_existing_files = 1;
439 remove_existing_files = 0;
443 dereference_dest_dir_symlinks = 0;
449 error (1, 0, _("symbolic links are not supported on this system"));
452 case TARGET_DIRECTORY_OPTION:
453 target_directory = optarg;
460 backup_suffix_string = optarg;
462 case_GETOPT_HELP_CHAR;
463 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
470 n_files = argc - optind;
471 file = argv + optind;
475 error (0, 0, _("missing file argument"));
479 target_directory_specified = (target_directory != NULL);
480 if (!target_directory)
481 target_directory = file[n_files - 1];
483 /* If there's only one file argument, then pretend `.' was given
484 as the second argument. */
487 static char *dummy[2];
496 dest_is_dir = isdir (target_directory);
504 if (target_directory_specified && !dest_is_dir)
506 error (0, 0, _("specified target directory, `%s' is not a directory"),
511 backup_type = (make_backups
512 ? xget_version (_("backup type"), version_control_string)
515 if (target_directory_specified || n_files > 2)
518 unsigned int last_file_idx = (target_directory_specified
522 if (!target_directory_specified && !dest_is_dir)
524 _("when making multiple links, last argument must be a directory"));
525 for (i = 0; i <= last_file_idx; ++i)
526 errors += do_link (file[i], target_directory);
530 struct stat source_stats;
538 /* When the destination is specified with a trailing slash and the
539 source exists but is not a directory, convert the user's command
540 `ln source dest/' to `ln source dest/basename(source)'. */
542 if (dest[strlen (dest) - 1] == '/'
543 && lstat (source, &source_stats) == 0
544 && !S_ISDIR (source_stats.st_mode))
546 PATH_BASENAME_CONCAT (new_dest, dest, source);
553 errors = do_link (source, new_dest);