From 051ed9a79cbe9af13fc38f361126fa1da9038b13 Mon Sep 17 00:00:00 2001
From: sin <sin@2f30.org>
Date: Fri, 9 Aug 2013 15:04:02 +0100
Subject: [PATCH] Add halt(8)

This is a very barebones halt cmd.  Please make sure that your
system is in a proper state to halt 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 |  1 +
 halt.c   | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 halt.c

diff --git a/Makefile b/Makefile
index 1322fb4..46d28d3 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,7 @@ SRC = \
 
 ifeq ($(OS),linux)
 SRC += \
+	halt.c              \
 	insmod.c            \
 	lsmod.c             \
 	mkswap.c            \
diff --git a/halt.c b/halt.c
new file mode 100644
index 0000000..3408988
--- /dev/null
+++ b/halt.c
@@ -0,0 +1,40 @@
+/* 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 [-p]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int pflag = 0;
+	int cmd = LINUX_REBOOT_CMD_HALT;
+
+	ARGBEGIN {
+	case 'p':
+		pflag = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc > 0)
+		usage();
+
+	sync();
+
+	if (pflag)
+		cmd = LINUX_REBOOT_CMD_POWER_OFF;
+
+	if (syscall(__NR_reboot, 0xfee1dead, 672274793,
+		    cmd, NULL) < 0)
+		eprintf("reboot:");
+	return 0;
+}