Change to runlevel 0/6 on reboot/halt/poweroff

This patch fixes a long-standing issue with how Finit handles shutdown,
reboot and poweroff -- and even runlevel changes to runlevel 0 and 6.

Prior to this patch sig.c:do_shutdown() was called immediately on any
of the above events, disregarding any services that a user might have
wanted to run as part of the shutdown/reboot.

With this change the handling is unified in all frontends to instead
do a runlevel change followed by the do_shutdown() action.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

TODO.md

@@ -20,8 +20,6 @@ General
 
 * Add halt/poweroff/shutdown symlinks to finit and convert reboot, but
   only install symlinks if these tools don't already exist.
-* Step state machine at shutdown instead of killing, same as shifting to
-  runlevel 0 or 6, then call external (newly installed?) tool to reboot.
 * Add support for timed shutdown in Finit, including cancelled shutdown.
 * SysV init and systemd use SIGUSR1 to restart their FIFO/D-Bus.  Add
   API restart to SIGHUP callback for the same functionality in Finit.

api.c

@@ -217,9 +217,14 @@ static int do_handle_emit(char *buf, size_t len)
 	return result;
 }
 
+/*
+ * In contrast to the SysV compat handling in plugins/initctl.c, when
+ * `initctl runlevel 0` is issued we default to POWERDOWN the system
+ * instead of just halting.
+ */
 static void cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 {
-	int sd;
+	int sd, lvl;
 	struct init_request rq;
 
 	sd = accept(w->fd, NULL, NULL);
@@ -255,26 +260,19 @@ static void cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 		switch (rq.cmd) {
 		case INIT_CMD_RUNLVL:
 			switch (rq.runlevel) {
-			case '0':
-				_d("Halting system (SIGUSR2)");
-				do_shutdown(SHUT_OFF);
-				break;
-
 			case 's':
 			case 'S':
-				_d("Cannot enter bootstrap after boot ...");
+				rq.runlevel = '1'; /* Single user mode */
-				rq.runlevel = '1';
 				/* Fall through to regular processing */
 
-			case '1'...'5':
+			case '0'...'9':
-			case '7'...'9':
 				_d("Setting new runlevel %c", rq.runlevel);
-				service_runlevel(rq.runlevel - '0');
+				lvl = rq.runlevel - '0';
-				break;
+				if (lvl == 0)
-
+					halt = SHUT_OFF;
-			case '6':
+				if (lvl == 6)
-				_d("Rebooting system (SIGUSR1)");
+					halt = SHUT_REBOOT;
-				do_shutdown(SHUT_REBOOT);
+				service_runlevel(lvl);
 				break;
 
 			default:

plugins/initctl.c

@@ -39,13 +39,6 @@
 #include "../sig.h"
 #include "../service.h"
 
-/*
- * Old-style SysV shutdown sends a setenv cmd INIT_HALT with "=HALT",
- * "=POWERDOWN", or "" to cancel shutdown, before requesting change to
- * runlevel 6 over the /dev/initctl FIFO.
- */
-shutop_t halt = SHUT_DEFAULT;
-
 static void parse(void *arg, int fd, int events);
 static void setup(void *arg);
 
@@ -99,11 +92,15 @@ static void set_env(char *data)
 }
 
 /*
- * Standard reboot/shutdown utilities talk to init using /dev/initctl.
+ * Standard reboot/shutdown utilities talk to init using /run/initctl.
  * We should check if the fifo was recreated and reopen it.
+ *
+ * For SysV compatibility the default is to halt the system when issuing
+ * `init 0`, unless INIT_HALT=POWERDOWN, as performed by the SysV utils.
  */
 static void parse(void *UNUSED(arg), int fd, int UNUSED(events))
 {
+	int lvl;
 	struct init_request rq;
 
 	while (1) {
@@ -132,25 +129,17 @@ static void parse(void *UNUSED(arg), int fd, int UNUSED(events))
 		switch (rq.cmd) {
 		case INIT_CMD_RUNLVL:
 			switch (rq.runlevel) {
-			case '0':
-				_d("Halting system (SIGUSR1 or SIGUSR2)");
-				do_shutdown(halt);
-				break;
-
 			case 's':
 			case 'S':
 				rq.runlevel = '1';
 				/* Fall through to regular processing */
 
-			case '1'...'5':
+			case '0'...'9':
-			case '7'...'9':
 				_d("Setting new runlevel %c", rq.runlevel);
-				service_runlevel(rq.runlevel - '0');
+				lvl = rq.runlevel - '0';
-				break;
+				if (lvl == 6)
-
+					halt = SHUT_REBOOT;
-			case '6':
+				service_runlevel(lvl);
-				_d("Rebooting system (SIGTERM)");
-				do_shutdown(SHUT_REBOOT);
 				break;
 
 			default:

sig.c

@@ -80,6 +80,13 @@
 #include "service.h"
 #include "utmp-api.h"
 
+/*
+ * Old-style SysV shutdown sends a setenv cmd INIT_HALT with "=HALT",
+ * "=POWERDOWN", or "" to cancel shutdown, before requesting change to
+ * runlevel 6 over the /dev/initctl FIFO.  See plugins/initctl.c
+ */
+shutop_t halt = SHUT_DEFAULT;
+
 static int   stopped = 0;
 static uev_t sigterm_watcher, sigusr1_watcher, sigusr2_watcher;
 static uev_t sighup_watcher,  sigint_watcher,  sigpwr_watcher;
@@ -184,7 +191,8 @@ static void sighup_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
  */
 static void sigint_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
-	do_shutdown(SHUT_REBOOT);
+	halt = SHUT_REBOOT;
+	service_runlevel(6);
 }
 
 /*
@@ -192,7 +200,8 @@ static void sigint_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
  */
 static void sigusr1_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
-	do_shutdown(SHUT_HALT);
+	halt = SHUT_HALT;
+	service_runlevel(0);
 }
 
 /*
@@ -200,7 +209,8 @@ static void sigusr1_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
  */
 static void sigusr2_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
-	do_shutdown(SHUT_OFF);
+	halt = SHUT_OFF;
+	service_runlevel(0);
 }
 
 /*
@@ -208,7 +218,8 @@ static void sigusr2_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
  */
 static void sigterm_cb(uev_t *UNUSED(w), void *UNUSED(arg), int UNUSED(events))
 {
-	do_shutdown(SHUT_REBOOT);
+	halt = SHUT_REBOOT;
+	service_runlevel(6);
 }
 
 /*

sig.h

@@ -66,6 +66,8 @@ typedef enum {
 	SHUT_REBOOT
 } shutop_t;
 
+extern shutop_t halt;
+
 void do_shutdown    (shutop_t op);
 int  sig_stopped    (void);
 void sig_init       (void);

sm.c

@@ -160,13 +160,14 @@ restart:
 		/* Cleanup stale services */
 		svc_clean_dynamic(service_unregister);
 
-		if (0 == runlevel) {
+		/*
-			do_shutdown(SHUT_OFF);
+		 * "I've seen things you people wouldn't believe.  Attack ships on fire off
-			sm->state = SM_RUNNING_STATE;
+		 *  the shoulder of Orion.  I watched C-beams glitter in the dark near the
-			break;
+		 *  Tannhäuser Gate.  All those .. moments .. will be lost in time, like
-		}
+		 *  tears ... in ... rain."
-		if (6 == runlevel) {
+		 */
-			do_shutdown(SHUT_REBOOT);
+		if (runlevel == 0 || runlevel == 6) {
+			do_shutdown(halt);
 			sm->state = SM_RUNNING_STATE;
 			break;
 		}