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-rw-r--r--toys/other/pivot_root.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/toys/other/pivot_root.c b/toys/other/pivot_root.c
new file mode 100644
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+++ b/toys/other/pivot_root.c
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+/* pivot_root.c - edit system mount tree
+ *
+ * Copyright 2012 Rob Landley <rob@landley.net>
+
+USE_PIVOT_ROOT(NEWTOY(pivot_root, "<2>2", TOYFLAG_USR|TOYFLAG_BIN))
+
+config PIVOT_ROOT
+ bool "pivot_root"
+ default y
+ help
+ usage: pivot_root OLD NEW
+
+ Swap OLD and NEW filesystems (as if by simultaneous mount --move), and
+ move all processes with chdir or chroot under OLD into NEW (including
+ kernel threads) so OLD may be unmounted.
+
+ The directory NEW must exist under OLD. This doesn't work on initramfs,
+ which can't be moved (about the same way PID 1 can't be killed; see
+ switch_root instead).
+*/
+
+#define FOR_pivot_root
+#include "toys.h"
+
+#include <linux/unistd.h>
+
+void pivot_root_main(void)
+{
+ if (syscall(__NR_pivot_root, toys.optargs[0], toys.optargs[1]))
+ perror_exit("'%s' -> '%s'", toys.optargs[0], toys.optargs[1]);
+}