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 <stdio.h>
  15 #include <stdlib.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include "busybox.h"
  19
  20 #define LN_SYMLINK          1
  21 #define LN_FORCE            2
  22 #define LN_NODEREFERENCE    4
  23 #define LN_BACKUP           8
  24 #define LN_SUFFIX           16
  25
  26 int ln_main(int argc, char **argv)
  27 {
  28         int status = EXIT_SUCCESS;
  29         int flag;
  30         char *last;
  31         char *src_name;
  32         char *src;
  33         char *suffix = "~";
  34         struct stat statbuf;
  35         int (*link_func)(const char *, const char *);
  36
  37         flag = bb_getopt_ulflags(argc, argv, "sfnbS:", &suffix);
  38
  39         if (argc == optind) {
  40                 bb_show_usage();
  41         }
  42
  43         last = argv[argc - 1];
  44         argv += optind;
  45
  46         if (argc == optind + 1) {
  47                 *--argv = last;
  48                 last = bb_get_last_path_component(bb_xstrdup(last));
  49         }
  50
  51         do {
  52                 src_name = NULL;
  53                 src = last;
  54
  55                 if (is_directory(src,
  56                                                  (flag & LN_NODEREFERENCE) ^ LN_NODEREFERENCE,
  57                                                  NULL)) {
  58                         src_name = bb_xstrdup(*argv);
  59                         src = concat_path_file(src, bb_get_last_path_component(src_name));
  60                         free(src_name);
  61                         src_name = src;
  62                 }
  63                 if (!(flag & LN_SYMLINK) && stat(*argv, &statbuf)) {
  64                         bb_perror_msg("%s", *argv);
  65                         status = EXIT_FAILURE;
  66                         free(src_name);
  67                         continue;
  68                 }
  69
  70                 if (flag & LN_BACKUP) {
  71                                 char *backup;
  72                                 backup = bb_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 }