1 /* vi: set sw=4 ts=4: */
3 * Mini ln implementation for busybox
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 //config: bool "ln (4.5 kb)"
13 //config: ln is used to create hard or soft links between files.
15 //applet:IF_LN(APPLET_NOEXEC(ln, ln, BB_DIR_BIN, BB_SUID_DROP, ln))
17 //kbuild:lib-$(CONFIG_LN) += ln.o
19 /* BB_AUDIT SUSv3 compliant */
20 /* BB_AUDIT GNU options missing: -d, -F, -i, and -v. */
21 /* http://www.opengroup.org/onlinepubs/007904975/utilities/ln.html */
23 //usage:#define ln_trivial_usage
24 //usage: "[OPTIONS] TARGET... LINK|DIR"
25 //usage:#define ln_full_usage "\n\n"
26 //usage: "Create a link LINK or DIR/TARGET to the specified TARGET(s)\n"
27 //usage: "\n -s Make symlinks instead of hardlinks"
28 //usage: "\n -f Remove existing destinations"
29 //usage: "\n -n Don't dereference symlinks - treat like normal file"
30 //usage: "\n -b Make a backup of the target (if exists) before link operation"
31 //usage: "\n -S suf Use suffix instead of ~ when making backup files"
32 //usage: "\n -T 2nd arg must be a DIR"
33 //usage: "\n -v Verbose"
35 //usage:#define ln_example_usage
36 //usage: "$ ln -s BusyBox /tmp/ls\n"
37 //usage: "$ ls -l /tmp/ls\n"
38 //usage: "lrwxrwxrwx 1 root root 7 Apr 12 18:39 ls -> BusyBox*\n"
42 /* This is a NOEXEC applet. Be very careful! */
45 #define LN_SYMLINK (1 << 0)
46 #define LN_FORCE (1 << 1)
47 #define LN_NODEREFERENCE (1 << 2)
48 #define LN_BACKUP (1 << 3)
49 #define LN_SUFFIX (1 << 4)
50 #define LN_VERBOSE (1 << 5)
51 #define LN_LINKFILE (1 << 6)
53 int ln_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
54 int ln_main(int argc, char **argv)
56 int status = EXIT_SUCCESS;
61 char *suffix = (char*)"~";
63 int (*link_func)(const char *, const char *);
65 opts = getopt32(argv, "^" "sfnbS:vT" "\0" "-1", &suffix);
67 last = argv[argc - 1];
71 if ((opts & LN_LINKFILE) && argc > 2) {
72 bb_error_msg_and_die("-T accepts 2 args max");
76 /* "ln PATH/TO/FILE" -> "ln PATH/TO/FILE FILE" */
78 /* xstrdup is needed: "ln -s PATH/TO/FILE/" is equivalent to
79 * "ln -s PATH/TO/FILE/ FILE", not "ln -s PATH/TO/FILE FILE"
81 last = bb_get_last_path_component_strip(xstrdup(last));
89 (opts & LN_NODEREFERENCE) ^ LN_NODEREFERENCE
92 if (opts & LN_LINKFILE) {
93 bb_error_msg_and_die("'%s' is a directory", src);
95 src_name = xstrdup(*argv);
96 src = concat_path_file(src, bb_get_last_path_component_strip(src_name));
100 if (!(opts & LN_SYMLINK) && stat(*argv, &statbuf)) {
101 // coreutils: "ln dangling_symlink new_hardlink" works
102 if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
103 bb_simple_perror_msg(*argv);
104 status = EXIT_FAILURE;
110 if (opts & LN_BACKUP) {
112 backup = xasprintf("%s%s", src, suffix);
113 if (rename(src, backup) < 0 && errno != ENOENT) {
114 bb_simple_perror_msg(src);
115 status = EXIT_FAILURE;
121 * When the source and dest are both hard links to the same
122 * inode, a rename may succeed even though nothing happened.
123 * Therefore, always unlink().
126 } else if (opts & LN_FORCE) {
131 if (opts & LN_SYMLINK) {
135 if (opts & LN_VERBOSE) {
136 printf("'%s' -> '%s'\n", src, *argv);
139 if (link_func(*argv, src) != 0) {
140 bb_simple_perror_msg(src);
141 status = EXIT_FAILURE;
145 } while ((++argv)[1]);