1 /* `ln' program to create links between files.
2 Copyright (C) 86, 89, 90, 91, 1995-1999 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 /* A string describing type of link to make. For use in verbose
104 diagnostics and in error messages. */
105 static const char *link_type_string;
107 /* If nonzero, ask the user before removing existing files. */
108 static int interactive;
110 /* If nonzero, remove existing files unconditionally. */
111 static int remove_existing_files;
113 /* If nonzero, list each file as it is moved. */
116 /* If nonzero, allow the superuser to make hard links to directories. */
117 static int hard_dir_link;
119 /* If nonzero, and the specified destination is a symbolic link to a
120 directory, treat it just as if it were a directory. Otherwise, the
121 command `ln --force --no-dereference file symlink-to-dir' deletes
122 symlink-to-dir before creating the new link. */
123 static int dereference_dest_dir_symlinks = 1;
125 static struct option const long_options[] =
127 {"backup", optional_argument, NULL, 'b'},
128 {"directory", no_argument, NULL, 'F'},
129 {"no-dereference", no_argument, NULL, 'n'},
130 {"force", no_argument, NULL, 'f'},
131 {"interactive", no_argument, NULL, 'i'},
132 {"suffix", required_argument, NULL, 'S'},
133 {"target-directory", required_argument, NULL, TARGET_DIRECTORY_OPTION},
134 {"symbolic", no_argument, NULL, 's'},
135 {"verbose", no_argument, NULL, 'v'},
136 {"version-control", required_argument, NULL, 'V'}, /* Deprecated. FIXME. */
137 {GETOPT_HELP_OPTION_DECL},
138 {GETOPT_VERSION_OPTION_DECL},
142 /* Make a link DEST to the (usually) existing file SOURCE.
143 Symbolic links to nonexistent files are allowed.
144 If DEST is a directory, put the link to SOURCE in that directory.
145 Return 1 if there is an error, otherwise 0. */
148 do_link (const char *source, const char *dest)
150 struct stat source_stats;
151 struct stat dest_stats;
152 char *dest_backup = NULL;
155 /* Use stat here instead of lstat.
156 On SVR4, link does not follow symlinks, so this check disallows
157 making hard links to symlinks that point to directories. Big deal.
158 On other systems, link follows symlinks, so this check is right. */
161 if (STAT_LIKE_LINK (source, &source_stats) != 0)
163 error (0, errno, "%s", source);
167 if (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"), source);
181 lstat_status = lstat (dest, &dest_stats);
182 if (lstat_status != 0 && errno != ENOENT)
184 error (0, errno, "%s", 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, "%s", 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 || !symlink)
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"), source, dest);
242 if (lstat_status == 0 || lstat (dest, &dest_stats) == 0)
244 if (S_ISDIR (dest_stats.st_mode))
246 error (0, 0, _("%s: cannot overwrite directory"), dest);
251 fprintf (stderr, _("%s: replace `%s'? "), program_name, dest);
255 else if (!remove_existing_files && backup_type == none)
257 error (0, 0, _("%s: File exists"), dest);
261 if (backup_type != none)
263 char *tmp_backup = find_backup_file_name (dest, backup_type);
264 if (tmp_backup == NULL)
265 error (1, 0, _("virtual memory exhausted"));
266 dest_backup = (char *) alloca (strlen (tmp_backup) + 1);
267 strcpy (dest_backup, tmp_backup);
269 if (rename (dest, dest_backup))
273 error (0, errno, _("cannot backup `%s'"), dest);
281 /* Try to unlink DEST even if we may have renamed it. In some unusual
282 cases (when DEST and DEST_BACKUP are hard-links that refer to the
283 same file), rename succeeds and DEST remains. If we didn't remove
284 DEST in that case, the subsequent LINKFUNC call would fail. */
285 if (unlink (dest) && errno != ENOENT)
287 error (0, errno, _("cannot remove `%s'"), dest);
291 else if (errno != ENOENT)
293 error (0, errno, "%s", dest);
298 printf (_("create %s %s to %s\n"), link_type_string, dest, source);
300 if ((*linkfunc) (source, dest) == 0)
305 error (0, errno, _("cannot create %s `%s' to `%s'"), link_type_string,
310 if (rename (dest_backup, dest))
311 error (0, errno, _("cannot un-backup `%s'"), dest);
320 fprintf (stderr, _("Try `%s --help' for more information.\n"),
325 Usage: %s [OPTION]... TARGET [LINK_NAME]\n\
326 or: %s [OPTION]... TARGET... DIRECTORY\n\
327 or: %s [OPTION]... --target-directory=DIRECTORY TARGET...\n\
329 program_name, program_name, program_name);
331 Create a link to the specified TARGET with optional LINK_NAME. If there is\n\
332 more than one TARGET, the last argument must be a directory; create links\n\
333 in DIRECTORY to each TARGET. Create hard links by default, symbolic links\n\
334 with --symbolic. When creating hard links, each TARGET must exist.\n\
336 -b, --backup[=CONTROL] make a backup of each existing destination file\n\
337 -d, -F, --directory hard link directories (super-user only)\n\
338 -f, --force remove existing destination files\n\
339 -n, --no-dereference treat destination that is a symlink to a\n\
340 directory as if it were a normal file\n\
341 -i, --interactive prompt whether to remove destinations\n\
342 -s, --symbolic make symbolic links instead of hard links\n\
343 -S, --suffix=SUFFIX override the usual backup suffix\n\
344 --target-directory=DIRECTORY specify the DIRECTORY in which to create\n\
346 -v, --verbose print name of each file before linking\n\
347 --help display this help and exit\n\
348 --version output version information and exit\n\
352 The backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.\n\
353 The version control method may be selected via the --backup option or through\n\
354 the VERSION_CONTROL environment variable. Here are the values:\n\
356 none, off never make backups (even if --backup is given)\n\
357 numbered, t make numbered backups\n\
358 existing, nil numbered if numbered backups exist, simple otherwise\n\
359 simple, never always make simple backups\n\
361 puts (_("\nReport bugs to <bug-fileutils@gnu.org>."));
368 main (int argc, char **argv)
372 int make_backups = 0;
373 char *backup_suffix_string;
374 char *version_control_string = NULL;
375 char *target_directory = NULL;
376 int target_directory_specified;
377 unsigned int n_files;
381 program_name = argv[0];
382 setlocale (LC_ALL, "");
383 bindtextdomain (PACKAGE, LOCALEDIR);
384 textdomain (PACKAGE);
386 /* FIXME: consider not calling getenv for SIMPLE_BACKUP_SUFFIX unless
387 we'll actually use backup_suffix_string. */
388 backup_suffix_string = getenv ("SIMPLE_BACKUP_SUFFIX");
390 symbolic_link = remove_existing_files = interactive = verbose
394 while ((c = getopt_long (argc, argv, "bdfinsvFS:V:", long_options, NULL))
399 case 0: /* Long-named option. */
402 case 'V': /* FIXME: this is deprecated. Remove it in 2001. */
404 _("warning: --version-control (-V) is obsolete; support for\
405 it\nwill be removed in some future release. Use --backup=%s instead."
412 version_control_string = optarg;
419 remove_existing_files = 1;
423 remove_existing_files = 0;
427 dereference_dest_dir_symlinks = 0;
433 error (1, 0, _("symbolic links are not supported on this system"));
436 case TARGET_DIRECTORY_OPTION:
437 target_directory = optarg;
444 backup_suffix_string = optarg;
446 case_GETOPT_HELP_CHAR;
447 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
454 n_files = argc - optind;
455 file = argv + optind;
459 error (0, 0, _("missing file argument"));
463 target_directory_specified = (target_directory != NULL);
464 if (!target_directory)
465 target_directory = file[n_files - 1];
467 /* If there's only one file argument, then pretend `.' was given
468 as the second argument. */
471 static char *dummy[2];
480 dest_is_dir = isdir (target_directory);
487 link_type_string = _("symbolic link");
492 link_type_string = _("hard link");
495 link_type_string = _("link");
498 if (target_directory_specified && !dest_is_dir)
500 error (0, 0, _("specified target directory, `%s' is not a directory"),
505 backup_type = (make_backups
506 ? xget_version (_("--version-control"), version_control_string)
509 if (target_directory_specified || n_files > 2)
512 unsigned int last_file_idx = (target_directory_specified
516 if (!target_directory_specified && !dest_is_dir)
518 _("when making multiple links, last argument must be a directory"));
519 for (i = 0; i <= last_file_idx; ++i)
520 errors += do_link (file[i], target_directory);
524 struct stat source_stats;
532 /* When the destination is specified with a trailing slash and the
533 source exists but is not a directory, convert the user's command
534 `ln source dest/' to `ln source dest/basename(source)'. */
536 if (dest[strlen (dest) - 1] == '/'
537 && lstat (source, &source_stats) == 0
538 && !S_ISDIR (source_stats.st_mode))
540 PATH_BASENAME_CONCAT (new_dest, dest, source);
547 errors = do_link (source, new_dest);