add ability for openrc-shutdown to communicate with sysvinit

This fixes #315.

src/rc/Makefile

@@ -14,7 +14,8 @@ SRCS+=		rc-selinux.c
 endif
 
 ifeq (${OS},Linux)
-SRCS+=		kill_all.c openrc-init.c openrc-shutdown.c broadcast.c rc-wtmp.c
+SRCS+=		kill_all.c openrc-init.c openrc-shutdown.c rc-sysvinit.c broadcast.c \
+			rc-wtmp.c
 endif
 
 CLEANFILES=	version.h rc-selinux.o
@@ -134,7 +135,7 @@ mountinfo: mountinfo.o _usage.o rc-misc.o
 openrc rc: rc.o rc-logger.o rc-misc.o rc-plugin.o _usage.o
 	${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
 
-openrc-shutdown: openrc-shutdown.o rc-misc.o _usage.o broadcast.o rc-wtmp.o
+openrc-shutdown: openrc-shutdown.o rc-misc.o _usage.o broadcast.o rc-wtmp.o rc-sysvinit.o
 	${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
 
 openrc-run runscript: openrc-run.o _usage.o rc-misc.o rc-plugin.o

src/rc/openrc-shutdown.c

@@ -35,8 +35,9 @@
 #include "rc.h"
 #include "helpers.h"
 #include "rc-misc.h"
-#include "_usage.h"
+#include "rc-sysvinit.h"
 #include "rc-wtmp.h"
+#include "_usage.h"
 
 const char *applet = NULL;
 const char *extraopts = NULL;
@@ -328,15 +329,17 @@ int main(int argc, char **argv)
 	syslog(LOG_NOTICE, "The system will %s now", state);
 	unlink(nologin_file);
 	unlink(shutdown_pid);
-	if (do_halt)
+	if (do_halt) {
+		sysvinit_runlevel('0');
 		send_cmd("halt");
-	else if (do_kexec)
+	} else if (do_kexec)
 		send_cmd("kexec");
 	else if (do_poweroff)
 		send_cmd("poweroff");
-	else if (do_reboot)
+	else if (do_reboot) {
+		sysvinit_runlevel('6');
 			send_cmd("reboot");
-	else if (do_single)
+	} else if (do_single)
 		send_cmd("single");
 	return 0;
 }

src/rc/rc-sysvinit.c

@@ -0,0 +1,66 @@
+/*
+ * rc-sysvinit.c
+ * Helper to send a runlevel change to sysvinit
+ */
+
+/*
+ * Copyright (c) 2019 The OpenRC Authors.
+ * See the Authors file at the top-level directory of this distribution and
+ * https://github.com/OpenRC/openrc/blob/master/AUTHORS
+ *
+ * This file is part of OpenRC. It is subject to the license terms in
+ * the LICENSE file found in the top-level directory of this
+ * distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
+ * This file may not be copied, modified, propagated, or distributed
+ *    except according to the terms contained in the LICENSE file.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "einfo.h"
+#include "rc-sysvinit.h"
+
+void sysvinit_runlevel(char rl)
+{
+	struct init_request request;
+	int fd;
+	char *p;
+	size_t bytes;
+	ssize_t r;
+
+	if (!rl)
+		return;
+
+	fd = open("/run/initctl", O_WRONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY);
+	if (fd < 0) {
+		if (errno != ENOENT)
+			eerror("Failed to open initctl fifo: %s", strerror(errno));
+		return;
+	}
+	request = (struct init_request) {
+		.magic = INIT_MAGIC,
+		.sleeptime = 0,
+		.cmd = INIT_CMD_RUNLVL,
+		.runlevel = rl,
+	};
+	p = (char *) &request;
+	bytes = sizeof(request);
+	do {
+		r = write(fd, p, bytes);
+		if (r < 0) {
+			if ((errno == EAGAIN) || (errno == EINTR))
+				continue;
+			eerror("Failed to write to /run/initctl: %s", strerror(errno));
+			return;
+		}
+		p += r;
+		bytes -= r;
+	} while (bytes > 0);
+	exit(0);
+}

src/rc/rc-sysvinit.h

@@ -0,0 +1,71 @@
+/*
+ * rc-sysvinit.h	- Interface to communicate with sysvinit via /run/initctl.
+ */
+
+/*
+ * Copyright (c) 2019 The OpenRC Authors.
+ * See the Authors file at the top-level directory of this distribution and
+ * https://github.com/OpenRC/openrc/blob/master/AUTHORS
+ *
+ * This file is part of OpenRC. It is subject to the license terms in
+ * the LICENSE file found in the top-level directory of this
+ * distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
+ * This file may not be copied, modified, propagated, or distributed
+ *    except according to the terms contained in the LICENSE file.
+ */
+
+#ifndef _RC_SYSVINIT_H
+#define _RC_SYSVINIT_H
+
+/*
+ * The #defines and structures below are taken from initreq.h in
+ * sysvinit and must be used by any program wishing to communicate with
+ * it.
+ */
+
+#define INIT_MAGIC 0x03091969
+#define INIT_CMD_START		0
+#define INIT_CMD_RUNLVL		1
+#define INIT_CMD_POWERFAIL	2
+#define INIT_CMD_POWERFAILNOW	3
+#define INIT_CMD_POWEROK	4
+#define INIT_CMD_BSD		5
+#define INIT_CMD_SETENV		6
+#define INIT_CMD_UNSETENV	7
+
+/*
+ *	This is what BSD 4.4 uses when talking to init.
+ *	Linux doesn't use this right now.
+ */
+struct init_request_bsd {
+	char	gen_id[8];		/* Beats me.. telnetd uses "fe" */
+	char	tty_id[16];		/* Tty name minus /dev/tty      */
+	char	host[64];	/* Hostname                     */
+	char	term_type[16];		/* Terminal type                */
+	int	signal;			/* Signal to send               */
+	int	pid;			/* Process to send to           */
+	char	exec_name[128];	        /* Program to execute           */
+	char	reserved[128];		/* For future expansion.        */
+};
+
+/*
+ *	Because of legacy interfaces, "runlevel" and "sleeptime"
+ *	aren't in a seperate struct in the union.
+ *
+ *	The weird sizes are because init expects the whole
+ *	struct to be 384 bytes.
+ */
+struct init_request {
+	int	magic;			/* Magic number                 */
+	int	cmd;			/* What kind of request         */
+	int	runlevel;		/* Runlevel to change to        */
+	int	sleeptime;		/* Time between TERM and KILL   */
+	union {
+		struct init_request_bsd	bsd;
+		char			data[368];
+	} i;
+};
+
+void sysvinit_runlevel(char rl);
+
+#endif