mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-12-12 14:05:40 +00:00
39acf45335
function old new delta switch_root_main 402 401 -1 rootdev 8 - -8 delete_contents 226 179 -47 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 0/2 up/down: 0/-56) Total: -56 bytes
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/* Copyright 2005 Rob Landley <rob@landley.net>
|
|
*
|
|
* Switch from rootfs to another filesystem as the root of the mount tree.
|
|
*
|
|
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
|
|
*/
|
|
|
|
#include "libbb.h"
|
|
#include <sys/vfs.h>
|
|
|
|
// Make up for header deficiencies.
|
|
#ifndef RAMFS_MAGIC
|
|
#define RAMFS_MAGIC ((unsigned)0x858458f6)
|
|
#endif
|
|
|
|
#ifndef TMPFS_MAGIC
|
|
#define TMPFS_MAGIC ((unsigned)0x01021994)
|
|
#endif
|
|
|
|
#ifndef MS_MOVE
|
|
#define MS_MOVE 8192
|
|
#endif
|
|
|
|
// Recursively delete contents of rootfs.
|
|
static void delete_contents(const char *directory, dev_t rootdev)
|
|
{
|
|
DIR *dir;
|
|
struct dirent *d;
|
|
struct stat st;
|
|
|
|
// Don't descend into other filesystems
|
|
if (lstat(directory, &st) || st.st_dev != rootdev)
|
|
return;
|
|
|
|
// Recursively delete the contents of directories.
|
|
if (S_ISDIR(st.st_mode)) {
|
|
dir = opendir(directory);
|
|
if (dir) {
|
|
while ((d = readdir(dir))) {
|
|
char *newdir = d->d_name;
|
|
|
|
// Skip . and ..
|
|
if (DOT_OR_DOTDOT(newdir))
|
|
continue;
|
|
|
|
// Recurse to delete contents
|
|
newdir = concat_path_file(directory, newdir);
|
|
delete_contents(newdir, rootdev);
|
|
free(newdir);
|
|
}
|
|
closedir(dir);
|
|
|
|
// Directory should now be empty. Zap it.
|
|
rmdir(directory);
|
|
}
|
|
|
|
// It wasn't a directory. Zap it.
|
|
} else unlink(directory);
|
|
}
|
|
|
|
int switch_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
|
int switch_root_main(int argc UNUSED_PARAM, char **argv)
|
|
{
|
|
char *newroot, *console = NULL;
|
|
struct stat st1, st2;
|
|
struct statfs stfs;
|
|
dev_t rootdev;
|
|
|
|
// Parse args (-c console)
|
|
opt_complementary = "-2"; // minimum 2 params
|
|
getopt32(argv, "+c:", &console); // '+': stop parsing at first non-option
|
|
argv += optind;
|
|
|
|
// Change to new root directory and verify it's a different fs.
|
|
newroot = *argv++;
|
|
|
|
xchdir(newroot);
|
|
if (lstat(".", &st1) || lstat("/", &st2) || st1.st_dev == st2.st_dev) {
|
|
bb_error_msg_and_die("bad newroot %s", newroot);
|
|
}
|
|
rootdev = st2.st_dev;
|
|
|
|
// Additional sanity checks: we're about to rm -rf /, so be REALLY SURE
|
|
// we mean it. (I could make this a CONFIG option, but I would get email
|
|
// from all the people who WILL eat their filesystems.)
|
|
if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs)
|
|
|| (((unsigned)stfs.f_type != RAMFS_MAGIC) && ((unsigned)stfs.f_type != TMPFS_MAGIC))
|
|
|| (getpid() != 1)
|
|
) {
|
|
bb_error_msg_and_die("not rootfs");
|
|
}
|
|
|
|
// Zap everything out of rootdev
|
|
delete_contents("/", rootdev);
|
|
|
|
// Overmount / with newdir and chroot into it. The chdir is needed to
|
|
// recalculate "." and ".." links.
|
|
if (mount(".", "/", NULL, MS_MOVE, NULL))
|
|
bb_error_msg_and_die("error moving root");
|
|
xchroot(".");
|
|
xchdir("/");
|
|
|
|
// If a new console specified, redirect stdin/stdout/stderr to that.
|
|
if (console) {
|
|
close(0);
|
|
xopen(console, O_RDWR);
|
|
xdup2(0, 1);
|
|
xdup2(0, 2);
|
|
}
|
|
|
|
// Exec real init. (This is why we must be pid 1.)
|
|
execv(argv[0], argv);
|
|
bb_perror_msg_and_die("bad init %s", argv[0]);
|
|
}
|