1/* vi: set sw=4 ts=4: */ 2/* 3 * pivot_root.c - Change root file system. Based on util-linux 2.10s 4 * 5 * busyboxed by Evin Robertson 6 * pivot_root syscall stubbed by Erik Andersen, so it will compile 7 * regardless of the kernel being used. 8 * 9 * Licensed under GPLv2, see file LICENSE in this source tree. 10 */ 11//config:config PIVOT_ROOT 12//config: bool "pivot_root (1.1 kb)" 13//config: default y 14//config: select PLATFORM_LINUX 15//config: help 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'. 20//config: 21//config: Note: This is for initrd in linux 2.4. Under initramfs (introduced 22//config: in linux 2.6) use switch_root instead. 23 24//applet:IF_PIVOT_ROOT(APPLET_NOFORK(pivot_root, pivot_root, BB_DIR_SBIN, BB_SUID_DROP, pivot_root)) 25 26//kbuild:lib-$(CONFIG_PIVOT_ROOT) += pivot_root.o 27 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" 33 34#include "libbb.h" 35 36extern int pivot_root(const char *new_root, const char *put_old); 37 38int pivot_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 39int pivot_root_main(int argc, char **argv) 40{ 41 if (argc != 3) 42 bb_show_usage(); 43 44 /* NOFORK applet. Hardly matters wrt performance, but code is trivial */ 45 46 if (pivot_root(argv[1], argv[2]) < 0) { 47 /* prints "pivot_root: <strerror text>" */ 48 bb_perror_nomsg_and_die(); 49 } 50 51 return EXIT_SUCCESS; 52} 53