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429 lines
11 KiB
C
429 lines
11 KiB
C
/* `ln' program to create links between files.
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Copyright (C) 1986, 1989, 1990, 1991, 1995 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* Written by Mike Parker and David MacKenzie. */
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#ifdef _AIX
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#pragma alloca
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#endif
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#include <config.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <getopt.h>
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#include "system.h"
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#include "backupfile.h"
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#include "version.h"
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#include "error.h"
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int link (); /* Some systems don't declare this anywhere. */
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#ifdef S_ISLNK
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int symlink ();
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#endif
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/* Construct a string NEW_DEST by concatenating DEST, a slash, and
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basename(SOURCE) in alloca'd memory. Don't modify DEST or SOURCE. */
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#define PATH_BASENAME_CONCAT(new_dest, dest, source) \
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do \
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{ \
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char *source_base; \
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char *tmp_source; \
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\
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tmp_source = (char *) alloca (strlen ((source)) + 1); \
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strcpy (tmp_source, (source)); \
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strip_trailing_slashes (tmp_source); \
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source_base = basename (tmp_source); \
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\
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(new_dest) = (char *) alloca (strlen ((dest)) + 1 \
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+ strlen (source_base) + 1); \
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stpcpy (stpcpy (stpcpy ((new_dest), (dest)), "/"), source_base);\
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} \
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while (0)
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char *basename ();
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enum backup_type get_version ();
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int isdir ();
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int yesno ();
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void strip_trailing_slashes ();
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char *stpcpy ();
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/* The name by which the program was run, for error messages. */
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char *program_name;
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/* A pointer to the function used to make links. This will point to either
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`link' or `symlink'. */
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static int (*linkfunc) ();
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/* If nonzero, make symbolic links; otherwise, make hard links. */
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static int symbolic_link;
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/* If nonzero, ask the user before removing existing files. */
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static int interactive;
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/* If nonzero, remove existing files unconditionally. */
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static int remove_existing_files;
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/* If nonzero, list each file as it is moved. */
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static int verbose;
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/* If nonzero, allow the superuser to make hard links to directories. */
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static int hard_dir_link;
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/* If nonzero, and the specified destination is a symbolic link to a
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directory, treat it just as if it were a directory. Otherwise, the
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command `ln --force --no-dereference file symlink-to-dir' deletes
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symlink-to-dir before creating the new link. */
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static int dereference_dest_dir_symlinks = 1;
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/* If non-zero, display usage information and exit. */
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static int show_help;
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/* If non-zero, print the version on standard output and exit. */
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static int show_version;
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static struct option const long_options[] =
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{
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{"backup", no_argument, NULL, 'b'},
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{"directory", no_argument, &hard_dir_link, 1},
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{"no-dereference", no_argument, NULL, 'n'},
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{"force", no_argument, NULL, 'f'},
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{"interactive", no_argument, NULL, 'i'},
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{"suffix", required_argument, NULL, 'S'},
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{"symbolic", no_argument, &symbolic_link, 1},
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{"verbose", no_argument, &verbose, 1},
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{"version-control", required_argument, NULL, 'V'},
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{"help", no_argument, &show_help, 1},
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{"version", no_argument, &show_version, 1},
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{NULL, 0, NULL, 0}
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};
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/* Make a link DEST to the (usually) existing file SOURCE.
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Symbolic links to nonexistent files are allowed.
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If DEST is a directory, put the link to SOURCE in that directory.
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Return 1 if there is an error, otherwise 0. */
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static int
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do_link (char *source, char *dest)
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{
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struct stat dest_stats;
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char *dest_backup = NULL;
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int lstat_status;
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/* Use stat here instead of lstat.
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On SVR4, link does not follow symlinks, so this check disallows
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making hard links to symlinks that point to directories. Big deal.
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On other systems, link follows symlinks, so this check is right. */
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if (!symbolic_link)
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{
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struct stat source_stats;
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if (stat (source, &source_stats) != 0)
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{
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error (0, errno, "%s", source);
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return 1;
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}
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if (!hard_dir_link && S_ISDIR (source_stats.st_mode))
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{
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error (0, 0, "%s: hard link not allowed for directory", source);
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return 1;
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}
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}
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if (lstat (dest, &dest_stats) != 0 && errno != ENOENT)
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{
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error (0, errno, "%s", dest);
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return 1;
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}
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/* If the destination is a directory or (it is a symlink to a directory
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and the user has not specified --no-dereference), then form the
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actual destination name by appending basename (source) to the
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specified destination directory. */
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lstat_status = lstat (dest, &dest_stats);
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if (lstat_status != 0 && errno != ENOENT)
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{
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error (0, errno, "%s", dest);
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return 1;
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}
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if ((lstat_status == 0
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&& S_ISDIR (dest_stats.st_mode))
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#ifdef S_ISLNK
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|| (dereference_dest_dir_symlinks
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&& (S_ISLNK (dest_stats.st_mode)
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&& isdir (dest)))
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#endif
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)
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{
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/* Target is a directory; build the full filename. */
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char *new_dest;
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PATH_BASENAME_CONCAT (new_dest, dest, source);
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dest = new_dest;
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/* Set this to non-zero to force another call to lstat
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with the new destination. */
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lstat_status = 1;
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}
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if (lstat_status == 0 || lstat (dest, &dest_stats) == 0)
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{
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if (S_ISDIR (dest_stats.st_mode))
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{
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error (0, 0, "%s: cannot overwrite directory", dest);
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return 1;
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}
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if (interactive)
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{
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fprintf (stderr, "%s: replace `%s'? ", program_name, dest);
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if (!yesno ())
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return 0;
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}
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else if (!remove_existing_files)
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{
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error (0, 0, "%s: File exists", dest);
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return 1;
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}
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if (backup_type != none)
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{
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char *tmp_backup = find_backup_file_name (dest);
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if (tmp_backup == NULL)
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error (1, 0, "virtual memory exhausted");
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dest_backup = (char *) alloca (strlen (tmp_backup) + 1);
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strcpy (dest_backup, tmp_backup);
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free (tmp_backup);
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if (rename (dest, dest_backup))
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{
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if (errno != ENOENT)
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{
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error (0, errno, "cannot backup `%s'", dest);
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return 1;
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}
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else
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dest_backup = NULL;
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}
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}
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else if (unlink (dest) && errno != ENOENT)
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{
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error (0, errno, "cannot remove `%s'", dest);
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return 1;
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}
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}
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else if (errno != ENOENT)
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{
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error (0, errno, "%s", dest);
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return 1;
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}
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if (verbose)
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printf ("%s -> %s\n", source, dest);
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if ((*linkfunc) (source, dest) == 0)
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{
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return 0;
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}
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error (0, errno, "cannot %slink `%s' to `%s'",
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#ifdef S_ISLNK
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symbolic_link ? "symbolic " : "",
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#else
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"",
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#endif
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source, dest);
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if (dest_backup)
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{
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if (rename (dest_backup, dest))
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error (0, errno, "cannot un-backup `%s'", dest);
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}
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return 1;
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}
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static void
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usage (int status)
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{
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if (status != 0)
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fprintf (stderr, "Try `%s --help' for more information.\n",
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program_name);
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else
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{
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printf ("\
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Usage: %s [OPTION]... SOURCE [DEST]\n\
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or: %s [OPTION]... SOURCE... DIRECTORY\n\
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",
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program_name, program_name);
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printf ("\
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Link SOURCE to DEST (. by default), or multiple SOURCE(s) to DIRECTORY.\n\
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Makes hard links by default, symbolic links with -s.\n\
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\n\
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-b, --backup make backups for removed files\n\
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-d, -F, --directory hard link directories (super-user only)\n\
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-f, --force remove existing destinations\n\
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-n, --no-dereference with --force, remove destination that is a\n\
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symlink to a directory\n\
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-i, --interactive prompt whether to remove destinations\n\
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-s, --symbolic make symbolic links instead of hard links\n\
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-v, --verbose print name of each file before linking\n\
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-S, --suffix=SUFFIX override the usual backup suffix\n\
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-V, --version-control=WORD override the usual version control\n\
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--help display this help and exit\n\
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--version output version information and exit\n\
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\n\
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The backup suffix is ~, unless set with SIMPLE_BACKUP_SUFFIX. The\n\
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version control may be set with VERSION_CONTROL, values are:\n\
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\n\
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t, numbered make numbered backups\n\
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nil, existing numbered if numbered backups exist, simple otherwise\n\
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never, simple always make simple backups\n");
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}
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exit (status);
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}
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void
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main (int argc, char **argv)
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{
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int c;
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int errors;
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int make_backups = 0;
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char *version;
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version = getenv ("SIMPLE_BACKUP_SUFFIX");
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if (version)
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simple_backup_suffix = version;
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version = getenv ("VERSION_CONTROL");
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program_name = argv[0];
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linkfunc = link;
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symbolic_link = remove_existing_files = interactive = verbose
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= hard_dir_link = 0;
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errors = 0;
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while ((c = getopt_long (argc, argv, "bdfinsvFS:V:", long_options, (int *) 0))
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!= EOF)
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{
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switch (c)
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{
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case 0: /* Long-named option. */
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break;
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case 'b':
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make_backups = 1;
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break;
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case 'd':
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case 'F':
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hard_dir_link = 1;
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break;
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case 'f':
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remove_existing_files = 1;
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interactive = 0;
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break;
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case 'i':
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remove_existing_files = 0;
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interactive = 1;
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break;
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case 'n':
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dereference_dest_dir_symlinks = 0;
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break;
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case 's':
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#ifdef S_ISLNK
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symbolic_link = 1;
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#else
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error (1, 0, "symbolic links are not supported on this system");
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#endif
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break;
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case 'v':
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verbose = 1;
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break;
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case 'S':
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simple_backup_suffix = optarg;
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break;
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case 'V':
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version = optarg;
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break;
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default:
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usage (1);
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break;
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}
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}
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if (show_version)
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{
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printf ("ln - %s\n", version_string);
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exit (0);
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}
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if (show_help)
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usage (0);
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if (optind == argc)
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{
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error (0, 0, "missing file argument");
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usage (1);
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}
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if (make_backups)
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backup_type = get_version (version);
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#ifdef S_ISLNK
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if (symbolic_link)
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linkfunc = symlink;
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#endif
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if (optind == argc - 1)
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errors = do_link (argv[optind], ".");
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else if (optind == argc - 2)
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{
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struct stat source_stats;
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char *source;
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char *dest;
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char *new_dest;
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source = argv[optind];
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dest = argv[optind + 1];
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/* When the destination is specified with a trailing slash and the
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source exists but is not a directory, convert the user's command
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`ln source dest/' to `ln source dest/basename(source)'. */
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if (dest[strlen (dest) - 1] == '/'
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&& lstat (source, &source_stats) == 0
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&& !S_ISDIR (source_stats.st_mode))
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{
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PATH_BASENAME_CONCAT (new_dest, dest, source);
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}
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else
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{
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new_dest = dest;
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}
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errors = do_link (source, new_dest);
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}
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else
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{
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char *to;
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to = argv[argc - 1];
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if (!isdir (to))
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error (1, 0, "when making multiple links, last argument must be a directory");
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for (; optind < argc - 1; ++optind)
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errors += do_link (argv[optind], to);
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}
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exit (errors != 0);
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}
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