1 /* vi: set sw=4 ts=4: */
3 * pivot_root.c - Change root file system. Based on util-linux 2.10s
5 * busyboxed by Evin Robertson
6 * pivot_root syscall stubbed by Erik Andersen, so it will compile
7 * regardless of the kernel being used.
9 * Licensed under GPLv2, see file LICENSE in this source tree.
11 //config:config PIVOT_ROOT
12 //config: bool "pivot_root (898 bytes)"
14 //config: select PLATFORM_LINUX
16 //config: The pivot_root utility swaps the mount points for the root filesystem
17 //config: with some other mounted filesystem. This allows you to do all sorts
18 //config: of wild and crazy things with your Linux system and is far more
19 //config: powerful than 'chroot'.
21 //config: Note: This is for initrd in linux 2.4. Under initramfs (introduced
22 //config: in linux 2.6) use switch_root instead.
24 //applet:IF_PIVOT_ROOT(APPLET_NOFORK(pivot_root, pivot_root, BB_DIR_SBIN, BB_SUID_DROP, pivot_root))
26 //kbuild:lib-$(CONFIG_PIVOT_ROOT) += pivot_root.o
28 //usage:#define pivot_root_trivial_usage
29 //usage: "NEW_ROOT PUT_OLD"
30 //usage:#define pivot_root_full_usage "\n\n"
31 //usage: "Move the current root file system to PUT_OLD and make NEW_ROOT\n"
32 //usage: "the new root file system"
36 extern int pivot_root(const char *new_root, const char *put_old);
38 int pivot_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
39 int pivot_root_main(int argc, char **argv)
44 /* NOFORK applet. Hardly matters wrt performance, but code is trivial */
46 if (pivot_root(argv[1], argv[2]) < 0) {
47 /* prints "pivot_root: <strerror text>" */
48 bb_perror_nomsg_and_die();