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 "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
25int ln_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
26int 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}
107