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 source tree.
   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 "libbb.h"
  15
  16 /* This is a NOEXEC applet. Be very careful! */
  17
  18
  19 #define LN_SYMLINK          1
  20 #define LN_FORCE            2
  21 #define LN_NODEREFERENCE    4
  22 #define LN_BACKUP           8
  23 #define LN_SUFFIX           16
  24
  25 int ln_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  26 int ln_main(int argc, char **argv)
  27 {
  28         int status = EXIT_SUCCESS;
  29         int opts;
  30         char *last;
  31         char *src_name;
  32         char *src;
  33         char *suffix = (char*)"~";
  34         struct stat statbuf;
  35         int (*link_func)(const char *, const char *);
  36
  37         opt_complementary = "-1"; /* min one arg */
  38         opts = getopt32(argv, "sfnbS:", &suffix);
  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_strip(xstrdup(last));
  46         }
  47
  48         do {
  49                 src_name = NULL;
  50                 src = last;
  51
  52                 if (is_directory(src,
  53                                 (opts & LN_NODEREFERENCE) ^ LN_NODEREFERENCE,
  54                                 NULL)
  55                 ) {
  56                         src_name = xstrdup(*argv);
  57                         src = concat_path_file(src, bb_get_last_path_component_strip(src_name));
  58                         free(src_name);
  59                         src_name = src;
  60                 }
  61                 if (!(opts & LN_SYMLINK) && stat(*argv, &statbuf)) {
  62                         // coreutils: "ln dangling_symlink new_hardlink" works
  63                         if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
  64                                 bb_simple_perror_msg(*argv);
  65                                 status = EXIT_FAILURE;
  66                                 free(src_name);
  67                                 continue;
  68                         }
  69                 }
  70
  71                 if (opts & LN_BACKUP) {
  72                         char *backup;
  73                         backup = xasprintf("%s%s", src, suffix);
  74                         if (rename(src, backup) < 0 && errno != ENOENT) {
  75                                 bb_simple_perror_msg(src);
  76                                 status = EXIT_FAILURE;
  77                                 free(backup);
  78                                 continue;
  79                         }
  80                         free(backup);
  81                         /*
  82                          * When the source and dest are both hard links to the same
  83                          * inode, a rename may succeed even though nothing happened.
  84                          * Therefore, always unlink().
  85                          */
  86                         unlink(src);
  87                 } else if (opts & LN_FORCE) {
  88                         unlink(src);
  89                 }
  90
  91                 link_func = link;
  92                 if (opts & LN_SYMLINK) {
  93                         link_func = symlink;
  94                 }
  95
  96                 if (link_func(*argv, src) != 0) {
  97                         bb_simple_perror_msg(src);
  98                         status = EXIT_FAILURE;
  99                 }
 100
 101                 free(src_name);
 102
 103         } while ((++argv)[1]);
 104
 105         return status;
 106 }