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/* vi: set sw=4 ts=4: */
/*
* Mini ln implementation for busybox
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config LN
//config: bool "ln (4.9 kb)"
//config: default y
//config: help
//config: ln is used to create hard or soft links between files.
//applet:IF_LN(APPLET_NOEXEC(ln, ln, BB_DIR_BIN, BB_SUID_DROP, ln))
//kbuild:lib-$(CONFIG_LN) += ln.o
/* BB_AUDIT SUSv3 compliant */
/* BB_AUDIT GNU options missing: -d, -F, -i, and -v. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/ln.html */
//usage:#define ln_trivial_usage
//usage: "[-sfnbtv] [-S SUF] TARGET... LINK|DIR"
//usage:#define ln_full_usage "\n\n"
//usage: "Create a link LINK or DIR/TARGET to the specified TARGET(s)\n"
//usage: "\n -s Make symlinks instead of hardlinks"
//usage: "\n -f Remove existing destinations"
//usage: "\n -n Don't dereference symlinks - treat like normal file"
//usage: "\n -b Make a backup of the target (if exists) before link operation"
//usage: "\n -S SUF Use suffix instead of ~ when making backup files"
//usage: "\n -T Treat LINK as a file, not DIR"
//usage: "\n -v Verbose"
//usage:
//usage:#define ln_example_usage
//usage: "$ ln -s BusyBox /tmp/ls\n"
//usage: "$ ls -l /tmp/ls\n"
//usage: "lrwxrwxrwx 1 root root 7 Apr 12 18:39 ls -> BusyBox*\n"
#include "libbb.h"
/* This is a NOEXEC applet. Be very careful! */
#define LN_SYMLINK (1 << 0)
#define LN_FORCE (1 << 1)
#define LN_NODEREFERENCE (1 << 2)
#define LN_BACKUP (1 << 3)
#define LN_SUFFIX (1 << 4)
#define LN_VERBOSE (1 << 5)
#define LN_LINKFILE (1 << 6)
int ln_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ln_main(int argc, char **argv)
{
int status = EXIT_SUCCESS;
int opts;
char *last;
char *src_name;
char *src;
char *suffix = (char*)"~";
struct stat statbuf;
int (*link_func)(const char *, const char *);
opts = getopt32(argv, "^" "sfnbS:vT" "\0" "-1", &suffix);
/*
-s, --symbolic make symbolic links instead of hard links
-f, --force remove existing destination files
-n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory
-b like --backup but does not accept an argument
--backup[=CONTROL] make a backup of each existing destination file
-S, --suffix=SUFFIX override the usual backup suffix
-v, --verbose
-T, --no-target-directory
-d, -F, --directory allow the superuser to attempt to hard link directories
-i, --interactive prompt whether to remove destinations
-L, --logical dereference TARGETs that are symbolic links
-P, --physical make hard links directly to symbolic links
-r, --relative create symbolic links relative to link location
-t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links
*/
last = argv[argc - 1];
argv += optind;
argc -= optind;
if ((opts & LN_LINKFILE) && argc > 2) {
bb_simple_error_msg_and_die("-T accepts 2 args max");
}
if (!argv[1]) {
/* "ln PATH/TO/FILE" -> "ln PATH/TO/FILE FILE" */
*--argv = last;
/* xstrdup is needed: "ln -s PATH/TO/FILE/" is equivalent to
* "ln -s PATH/TO/FILE/ FILE", not "ln -s PATH/TO/FILE FILE"
*/
last = bb_get_last_path_component_strip(xstrdup(last));
}
do {
src_name = NULL;
src = last;
if (is_directory(src,
/*followlinks:*/ !(opts & (LN_NODEREFERENCE|LN_LINKFILE))
/* Why LN_LINKFILE does not follow links:
* -T/--no-target-directory implies -n/--no-dereference
*/
)
) {
if (opts & LN_LINKFILE) {
bb_error_msg_and_die("'%s' is a directory", src);
}
src_name = xstrdup(*argv);
src = concat_path_file(src, bb_get_last_path_component_strip(src_name));
free(src_name);
src_name = src;
}
if (!(opts & LN_SYMLINK) && stat(*argv, &statbuf)) {
// coreutils: "ln dangling_symlink new_hardlink" works
if (lstat(*argv, &statbuf) || !S_ISLNK(statbuf.st_mode)) {
bb_simple_perror_msg(*argv);
status = EXIT_FAILURE;
free(src_name);
continue;
}
}
if (opts & LN_BACKUP) {
char *backup;
backup = xasprintf("%s%s", src, suffix);
if (rename(src, backup) < 0 && errno != ENOENT) {
bb_simple_perror_msg(src);
status = EXIT_FAILURE;
free(backup);
continue;
}
free(backup);
/*
* When the source and dest are both hard links to the same
* inode, a rename may succeed even though nothing happened.
* Therefore, always unlink().
*/
unlink(src);
} else if (opts & LN_FORCE) {
unlink(src);
}
link_func = link;
if (opts & LN_SYMLINK) {
link_func = symlink;
}
if (opts & LN_VERBOSE) {
printf("'%s' -> '%s'\n", src, *argv);
}
if (link_func(*argv, src) != 0) {
bb_simple_perror_msg(src);
status = EXIT_FAILURE;
}
free(src_name);
} while ((++argv)[1]);
return status;
}
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