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);
26int 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 = (char*)"~";
34	struct stat statbuf;
35	int (*link_func)(const char *, const char *);
36
37	flag = getopt32(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(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		) {
59			src_name = xstrdup(*argv);
60			src = concat_path_file(src, bb_get_last_path_component(src_name));
61			free(src_name);
62			src_name = src;
63		}
64		if (!(flag & LN_SYMLINK) && stat(*argv, &statbuf)) {
65			// coreutils: "ln dangling_symlink new_hardlink" works
66			if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
67				bb_perror_msg("%s", *argv);
68				status = EXIT_FAILURE;
69				free(src_name);
70				continue;
71			}
72		}
73
74		if (flag & LN_BACKUP) {
75			char *backup;
76			backup = xasprintf("%s%s", src, suffix);
77			if (rename(src, backup) < 0 && errno != ENOENT) {
78				bb_perror_msg("%s", src);
79				status = EXIT_FAILURE;
80				free(backup);
81				continue;
82			}
83			free(backup);
84			/*
85			 * When the source and dest are both hard links to the same
86			 * inode, a rename may succeed even though nothing happened.
87			 * Therefore, always unlink().
88			 */
89			unlink(src);
90		} else if (flag & LN_FORCE) {
91			unlink(src);
92		}
93
94		link_func = link;
95		if (flag & LN_SYMLINK) {
96			link_func = symlink;
97		}
98
99		if (link_func(*argv, src) != 0) {
100			bb_perror_msg("%s", src);
101			status = EXIT_FAILURE;
102		}
103
104		free(src_name);
105
106	} while ((++argv)[1]);
107
108	return status;
109}
110