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Diffstat (limited to 'i/pc104/initrd/conf/busybox/util-linux/switch_root.c')
-rw-r--r--i/pc104/initrd/conf/busybox/util-linux/switch_root.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/i/pc104/initrd/conf/busybox/util-linux/switch_root.c b/i/pc104/initrd/conf/busybox/util-linux/switch_root.c
new file mode 100644
index 0000000..5a01fd6
--- /dev/null
+++ b/i/pc104/initrd/conf/busybox/util-linux/switch_root.c
@@ -0,0 +1,123 @@
+/* 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 "busybox.h"
+#include <sys/vfs.h>
+
+
+// Make up for header deficiencies.
+
+#ifndef RAMFS_MAGIC
+#define RAMFS_MAGIC 0x858458f6
+#endif
+
+#ifndef TMPFS_MAGIC
+#define TMPFS_MAGIC 0x01021994
+#endif
+
+#ifndef MS_MOVE
+#define MS_MOVE 8192
+#endif
+
+dev_t rootdev;
+
+// Recursively delete contents of rootfs.
+
+static void delete_contents(const char *directory)
+{
+ 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)) {
+ if((dir = opendir(directory))) {
+ while ((d = readdir(dir))) {
+ char *newdir=d->d_name;
+
+ // Skip . and ..
+ if(*newdir=='.' && (!newdir[1] || (newdir[1]=='.' && !newdir[2])))
+ continue;
+
+ // Recurse to delete contents
+ newdir = alloca(strlen(directory) + strlen(d->d_name) + 2);
+ sprintf(newdir, "%s/%s", directory, d->d_name);
+ delete_contents(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[]);
+int switch_root_main(int argc, char *argv[])
+{
+ char *newroot, *console=NULL;
+ struct stat st1, st2;
+ struct statfs stfs;
+
+ // Parse args (-c console)
+
+ opt_complementary = "-2";
+ getopt32(argc, argv, "c:", &console);
+
+ // Change to new root directory and verify it's a different fs.
+
+ newroot=argv[optind++];
+
+ if (chdir(newroot) || 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 filesystemss.)
+
+ if (lstat("/init", &st1) || !S_ISREG(st1.st_mode) || statfs("/", &stfs) ||
+ (stfs.f_type != RAMFS_MAGIC && stfs.f_type != TMPFS_MAGIC) ||
+ getpid() != 1)
+ {
+ bb_error_msg_and_die("not rootfs");
+ }
+
+ // Zap everything out of rootdev
+
+ delete_contents("/");
+
+ // Overmount / with newdir and chroot into it. The chdir is needed to
+ // recalculate "." and ".." links.
+
+ if (mount(".", "/", NULL, MS_MOVE, NULL) || chroot(".") || chdir("/"))
+ bb_error_msg_and_die("moving root");
+
+ // If a new console specified, redirect stdin/stdout/stderr to that.
+
+ if (console) {
+ close(0);
+ if(open(console, O_RDWR) < 0)
+ bb_error_msg_and_die("bad console '%s'", console);
+ dup2(0, 1);
+ dup2(0, 2);
+ }
+
+ // Exec real init. (This is why we must be pid 1.)
+ execv(argv[optind], argv+optind);
+ bb_error_msg_and_die("bad init '%s'", argv[optind]);
+}