Add reboot(8)

This is a very barebones reboot cmd.  Please make sure that your
system is in a proper state to reboot before using this.  This is
likely only useful for very barebones systems like an emergency
shell or similar.

Normally this command would be part of an actual init system.

Makefile

@@ -21,6 +21,7 @@ SRC += \
 	insmod.c            \
 	lsmod.c             \
 	mkswap.c            \
+	reboot.c            \
 	rmmod.c
 endif
 

reboot.c

@@ -0,0 +1,31 @@
+/* See LICENSE file for copyright and license details. */
+#include <linux/reboot.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc > 0)
+		usage();
+
+	sync();
+
+	if (syscall(__NR_reboot, 0xfee1dead, 672274793,
+		    LINUX_REBOOT_CMD_RESTART, NULL) < 0)
+		eprintf("reboot:");
+	return 0;
+}