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  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8  */
   9
  10 /* BB_AUDIT SUSv3 compliant */
  11 /* BB_AUDIT GNU options missing: -d, -F, -i, and -v. */
  12 /* http://www.opengroup.org/onlinepubs/007904975/utilities/ln.html */
  13
  14 #include "busybox.h"
  15
  16 #define LN_SYMLINK          1
  17 #define LN_FORCE            2
  18 #define LN_NODEREFERENCE    4
  19 #define LN_BACKUP           8
  20 #define LN_SUFFIX           16
  21
  22 int ln_main(int argc, char **argv);
  23 int ln_main(int argc, char **argv)
  24 {
  25         int status = EXIT_SUCCESS;
  26         int flag;
  27         char *last;
  28         char *src_name;
  29         char *src;
  30         char *suffix = (char*)"~";
  31         struct stat statbuf;
  32         int (*link_func)(const char *, const char *);
  33
  34         flag = getopt32(argc, argv, "sfnbS:", &suffix);
  35
  36         if (argc == optind) {
  37                 bb_show_usage();
  38         }
  39
  40         last = argv[argc - 1];
  41         argv += optind;
  42
  43         if (argc == optind + 1) {
  44                 *--argv = last;
  45                 last = bb_get_last_path_component(xstrdup(last));
  46         }
  47
  48         do {
  49                 src_name = NULL;
  50                 src = last;
  51
  52                 if (is_directory(src,
  53                                 (flag & LN_NODEREFERENCE) ^ LN_NODEREFERENCE,
  54                                 NULL)) {
  55                         src_name = xstrdup(*argv);
  56                         src = concat_path_file(src, bb_get_last_path_component(src_name));
  57                         free(src_name);
  58                         src_name = src;
  59                 }
  60                 if (!(flag & LN_SYMLINK) && stat(*argv, &statbuf)) {
  61                         // coreutils: "ln dangling_symlink new_hardlink" works
  62                         if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
  63                                 bb_perror_msg("%s", *argv);
  64                                 status = EXIT_FAILURE;
  65                                 free(src_name);
  66                                 continue;
  67                         }
  68                 }
  69
  70                 if (flag & LN_BACKUP) {
  71                         char *backup;
  72                         backup = xasprintf("%s%s", src, suffix);
  73                         if (rename(src, backup) < 0 && errno != ENOENT) {
  74                                 bb_perror_msg("%s", src);
  75                                 status = EXIT_FAILURE;
  76                                 free(backup);
  77                                 continue;
  78                         }
  79                         free(backup);
  80                         /*
  81                          * When the source and dest are both hard links to the same
  82                          * inode, a rename may succeed even though nothing happened.
  83                          * Therefore, always unlink().
  84                          */
  85                         unlink(src);
  86                 } else if (flag & LN_FORCE) {
  87                         unlink(src);
  88                 }
  89
  90                 link_func = link;
  91                 if (flag & LN_SYMLINK) {
  92                         link_func = symlink;
  93                 }
  94
  95                 if (link_func(*argv, src) != 0) {
  96                         bb_perror_msg("%s", src);
  97                         status = EXIT_FAILURE;
  98                 }
  99
 100                 free(src_name);
 101
 102         } while ((++argv)[1]);
 103
 104         return status;
 105 }