Diff of /trunk/mkinitrd-magellan/busybox/util-linux/switch_root.c

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	revision 532 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 816 by niro, Fri Apr 24 18:33:46 2009 UTC
#	Line 6	Line 6
6	* Licensed under GPL version 2, see file LICENSE in this tarball for details.	* Licensed under GPL version 2, see file LICENSE in this tarball for details.
7	*/	*/
8
9	#include "busybox.h"	#include "libbb.h"
10	#include <sys/vfs.h>	#include <sys/vfs.h>
11
12	// Make up for header deficiencies.	// Make up for header deficiencies.
13	#ifndef RAMFS_MAGIC	#ifndef RAMFS_MAGIC
14	#define RAMFS_MAGIC 0x858458f6	#define RAMFS_MAGIC ((unsigned)0x858458f6)
15	#endif	#endif
16
17	#ifndef TMPFS_MAGIC	#ifndef TMPFS_MAGIC
18	#define TMPFS_MAGIC 0x01021994	#define TMPFS_MAGIC ((unsigned)0x01021994)
19	#endif	#endif
20
21	#ifndef MS_MOVE	#ifndef MS_MOVE
22	#define MS_MOVE 8192	#define MS_MOVE     8192
23	#endif	#endif
24
	dev_t rootdev;
25	// Recursively delete contents of rootfs.	// Recursively delete contents of rootfs.
26		static void delete_contents(const char *directory, dev_t rootdev)
	static void delete_contents(char *directory)
27	{	{
28	DIR *dir;	DIR *dir;
29	struct dirent *d;	struct dirent *d;
30	struct stat st;	struct stat st;
31
32	// Don't descend into other filesystems	// Don't descend into other filesystems
33	if (lstat(directory, &st) || st.st_dev != rootdev) return;	if (lstat(directory, &st) || st.st_dev != rootdev)
34		return;
35
36	// Recursively delete the contents of directories.	// Recursively delete the contents of directories.
37	if (S_ISDIR(st.st_mode)) {	if (S_ISDIR(st.st_mode)) {
38	if((dir = opendir(directory))) {	dir = opendir(directory);
39		if (dir) {
40	while ((d = readdir(dir))) {	while ((d = readdir(dir))) {
41	char *newdir=d->d_name;	char *newdir = d->d_name;
42
43	// Skip . and ..	// Skip . and ..
44	if(*newdir=='.' && (!newdir[1] || (newdir[1]=='.' && !newdir[2])))	if (DOT_OR_DOTDOT(newdir))
45	continue;	continue;
46
47	// Recurse to delete contents	// Recurse to delete contents
48	newdir = alloca(strlen(directory) + strlen(d->d_name) + 2);	newdir = concat_path_file(directory, newdir);
49	sprintf(newdir, "%s/%s", directory, d->d_name);	delete_contents(newdir, rootdev);
50	delete_contents(newdir);	free(newdir);
51	}	}
52	closedir(dir);	closedir(dir);
53
#	Line 59  static void delete_contents(char *direct	Line 56  static void delete_contents(char *direct
56	}	}
57
58	// It wasn't a directory.  Zap it.	// It wasn't a directory.  Zap it.
59	} else unlink(directory);	} else unlink(directory);
60	}	}
61
62	int switch_root_main(int argc, char *argv[])	int switch_root_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
63		int switch_root_main(int argc UNUSED_PARAM, char **argv)
64	{	{
65	char *newroot, *console=NULL;	char *newroot, *console = NULL;
66	struct stat st1, st2;	struct stat st1, st2;
67	struct statfs stfs;	struct statfs stfs;
68		dev_t rootdev;
69
70	// Parse args (-c console)	// Parse args (-c console)
71		opt_complementary = "-2"; // minimum 2 params
72	opt_complementary = "-2";	getopt32(argv, "+c:", &console); // '+': stop parsing at first non-option
73	getopt32(argc, argv, "c:", &console);	argv += optind;
74
75	// Change to new root directory and verify it's a different fs.	// Change to new root directory and verify it's a different fs.
76		newroot = *argv++;
77
78	newroot=argv[optind++];	xchdir(newroot);
79		if (lstat(".", &st1) || lstat("/", &st2) || st1.st_dev == st2.st_dev) {
	if (chdir(newroot) || lstat(".", &st1) || lstat("/", &st2) ||
	st1.st_dev == st2.st_dev)
	{
80	bb_error_msg_and_die("bad newroot %s", newroot);	bb_error_msg_and_die("bad newroot %s", newroot);
81	}	}
82	rootdev=st2.st_dev;	rootdev = st2.st_dev;
83
84	// Additional sanity checks: we're about to rm -rf /,  so be REALLY SURE	// Additional sanity checks: we're about to rm -rf /,  so be REALLY SURE
85	// we mean it.  (I could make this a CONFIG option, but I would get email	// we mean it.  (I could make this a CONFIG option, but I would get email
86	// from all the people who WILL eat their filesystemss.)	// from all the people who WILL eat their filesystems.)
87		if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs)
88	if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs) ||	|| (((unsigned)stfs.f_type != RAMFS_MAGIC) && ((unsigned)stfs.f_type != TMPFS_MAGIC))
89	(stfs.f_type != RAMFS_MAGIC && stfs.f_type != TMPFS_MAGIC) ||	|| (getpid() != 1)
90	getpid() != 1)	) {
	{
91	bb_error_msg_and_die("not rootfs");	bb_error_msg_and_die("not rootfs");
92	}	}
93
94	// Zap everything out of rootdev	// Zap everything out of rootdev
95		delete_contents("/", rootdev);
	delete_contents("/");
96
97	// Overmount / with newdir and chroot into it.  The chdir is needed to	// Overmount / with newdir and chroot into it.  The chdir is needed to
98	// recalculate "." and ".." links.	// recalculate "." and ".." links.
99		if (mount(".", "/", NULL, MS_MOVE, NULL))
100	if (mount(".", "/", NULL, MS_MOVE, NULL) || chroot(".") || chdir("/"))	bb_error_msg_and_die("error moving root");
101	bb_error_msg_and_die("moving root");	xchroot(".");
102		xchdir("/");
103
104	// If a new console specified, redirect stdin/stdout/stderr to that.	// If a new console specified, redirect stdin/stdout/stderr to that.
105	if (console) {	if (console) {
106	close(0);	close(0);
107	if(open(console, O_RDWR) < 0)	xopen(console, O_RDWR);
108	bb_error_msg_and_die("bad console '%s'", console);	xdup2(0, 1);
109	dup2(0, 1);	xdup2(0, 2);
	dup2(0, 2);
110	}	}
111
112	// Exec real init.  (This is why we must be pid 1.)	// Exec real init.  (This is why we must be pid 1.)
113	execv(argv[optind], argv+optind);	execv(argv[0], argv);
114	bb_error_msg_and_die("bad init '%s'", argv[optind]);	bb_perror_msg_and_die("bad init %s", argv[0]);
115	}	}

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