coreutils/ln.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini ln implementation for busybox
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  *
  21  */
  22
  23 /* BB_AUDIT SUSv3 compliant */
  24 /* BB_AUDIT GNU options missing: -d, -F, -i, and -v. */
  25 /* http://www.opengroup.org/onlinepubs/007904975/utilities/ln.html */
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <unistd.h>
  30 #include <errno.h>
  31 #include "busybox.h"
  32
  33 #define LN_SYMLINK          1
  34 #define LN_FORCE            2
  35 #define LN_NODEREFERENCE    4
  36 #define LN_BACKUP           8
  37 #define LN_SUFFIX           16
  38
  39 int ln_main(int argc, char **argv)
  40 {
  41         int status = EXIT_SUCCESS;
  42         int flag;
  43         char *last;
  44         char *src_name;
  45         char *src;
  46         char *suffix = "~";
  47         struct stat statbuf;
  48         int (*link_func)(const char *, const char *);
  49
  50         flag = bb_getopt_ulflags(argc, argv, "sfnbS:", &suffix);
  51
  52         if (argc == optind) {
  53                 bb_show_usage();
  54         }
  55
  56         last = argv[argc - 1];
  57         argv += optind;
  58
  59         if (argc == optind + 1) {
  60                 *--argv = last;
  61                 last = bb_get_last_path_component(bb_xstrdup(last));
  62         }
  63
  64         do {
  65                 src_name = NULL;
  66                 src = last;
  67
  68                 if (is_directory(src,
  69                                                  (flag & LN_NODEREFERENCE) ^ LN_NODEREFERENCE,
  70                                                  NULL)) {
  71                         src_name = bb_xstrdup(*argv);
  72                         src = concat_path_file(src, bb_get_last_path_component(src_name));
  73                         free(src_name);
  74                         src_name = src;
  75                 }
  76                 if (!(flag & LN_SYMLINK) && stat(*argv, &statbuf)) {
  77                         bb_perror_msg("%s", *argv);
  78                         status = EXIT_FAILURE;
  79                         free(src_name);
  80                         continue;
  81                 }
  82
  83                 if (flag & LN_BACKUP) {
  84                                 char *backup;
  85                                 backup = bb_xasprintf("%s%s", src, suffix);
  86                                 if (rename(src, backup) < 0 && errno != ENOENT) {
  87                                                 bb_perror_msg("%s", src);
  88                                                 status = EXIT_FAILURE;
  89                                                 free(backup);
  90                                                 continue;
  91                                 }
  92                                 free(backup);
  93                                 /*
  94                                  * When the source and dest are both hard links to the same
  95                                  * inode, a rename may succeed even though nothing happened.
  96                                  * Therefore, always unlink().
  97                                  */
  98                                 unlink(src);
  99                 } else if (flag & LN_FORCE) {
 100                         unlink(src);
 101                 }
 102
 103                 link_func = link;
 104                 if (flag & LN_SYMLINK) {
 105                         link_func = symlink;
 106                 }
 107
 108                 if (link_func(*argv, src) != 0) {
 109                         bb_perror_msg("%s", src);
 110                         status = EXIT_FAILURE;
 111                 }
 112
 113                 free(src_name);
 114
 115         } while ((++argv)[1]);
 116
 117         return status;
 118 }