initd: restructure and merge service supervision code

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

6 files changed, 239 insertions, 215 deletions

diff --git a/initd/Makemodule.am b/initd/Makemodule.am
index f740885..54ae43d 100644
--- a/initd/Makemodule.am
+++ b/initd/Makemodule.am
@@ -1,5 +1,5 @@
 init_SOURCES = initd/main.c initd/init.h initd/signal_linux.c initd/runsvc.c
-init_SOURCES += initd/status.c initd/svclist.c
+init_SOURCES += initd/status.c initd/supervisor.c
 init_CPPFLAGS = $(AM_CPPFLAGS)
 init_CFLAGS = $(AM_CFLAGS)
 init_LDFLAGS = $(AM_LDFLAGS)
diff --git a/initd/init.h b/initd/init.h
index 2c39489..7d525a2 100644
--- a/initd/init.h
+++ b/initd/init.h
@@ -18,6 +18,16 @@
 #ifndef INIT_H
 #define INIT_H
 
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/socket.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <poll.h>
+
 #include <linux/reboot.h>
 #include <sys/signalfd.h>
 #include <sys/reboot.h>
@@ -36,6 +46,10 @@ enum {
 	STATUS_STARTED,
 };
 
+/********** main.c **********/
+
+void target_completed(int target);
+
 /********** runsvc.c **********/
 
 /*
@@ -45,12 +59,6 @@ enum {
 */
 pid_t runsvc(service_t *svc);
 
-/*
-	Start a service using runsvc, but wait until the child process
-	terminats and return its exit status.
-*/
-int runsvc_wait(service_t *svc);
-
 /********** status.c **********/
 
 /*
@@ -64,25 +72,15 @@ int runsvc_wait(service_t *svc);
 */
 void print_status(const char *msg, int type, bool update);
 
-/********** svclist.c **********/
+/********** supervisor.c **********/
 
-/*
-	Returns true if the list of running services contains
-	single shot processes.
-*/
-bool svclist_have_singleshot(void);
+void supervisor_handle_exited(pid_t pid, int status);
 
-/* Add a service to the list of running services */
-void svclist_add(service_t *svc);
+void supervisor_set_target(int next);
 
-/*
-	Remove a service, identifierd by PID, from the list of
-	running services.
+void supervisor_init(void);
 
-	Returns the service identified by the PID or NULL if there
-	is no such service.
-*/
-service_t *svclist_remove(pid_t pid);
+bool supervisor_process_queues(void);
 
 /********** signal_<platform>.c **********/
 
diff --git a/initd/main.c b/initd/main.c
index 2cacf12..78e8635 100644
--- a/initd/main.c
+++ b/initd/main.c
@@ -15,60 +15,14 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <sys/socket.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <errno.h>
-#include <poll.h>
-
 #include "init.h"
 
-static service_list_t cfg;
-
-static int target = TGT_BOOT;		/* runlevel we are targetting */
-static int runlevel = -1;		/* runlevel we are currently on */
+static int ti_sock = -1;
+static int sigfd = -1;
 
-static void handle_exited(service_t *svc)
-{
-	switch (svc->type) {
-	case SVC_RESPAWN:
-		if (target == TGT_REBOOT || target == TGT_SHUTDOWN)
-			break;
-
-		if (svc->rspwn_limit > 0) {
-			svc->rspwn_limit -= 1;
-
-			if (svc->rspwn_limit == 0) {
-				print_status(svc->desc, STATUS_FAIL, false);
-				break;
-			}
-		}
-
-		svc->pid = runsvc(svc);
-		if (svc->pid == -1) {
-			print_status(svc->desc, STATUS_FAIL, false);
-			break;
-		}
-
-		svclist_add(svc);
-		return;
-	case SVC_ONCE:
-		print_status(svc->desc,
-			     svc->status == EXIT_SUCCESS ?
-			     STATUS_OK : STATUS_FAIL, false);
-		break;
-	}
-	delsvc(svc);
-}
-
-static void handle_signal(int sigfd)
+static void handle_signal(void)
 {
 	struct signalfd_siginfo info;
-	service_t *svc;
 	int status;
 	pid_t pid;
 
@@ -83,10 +37,7 @@ static void handle_signal(int sigfd)
 			status = WIFEXITED(status) ? WEXITSTATUS(status) :
 						     EXIT_FAILURE;
 
-			svc = svclist_remove(pid);
-
-			if (svc != NULL)
-				handle_exited(svc);
+			supervisor_handle_exited(pid, status);
 		}
 		break;
 	case SIGINT:
@@ -95,41 +46,6 @@ static void handle_signal(int sigfd)
 	}
 }
 
-static void start_runlevel(int level)
-{
-	service_t *svc;
-	int status;
-
-	while (cfg.targets[level] != NULL) {
-		svc = cfg.targets[level];
-		cfg.targets[level] = svc->next;
-
-		if (svc->type == SVC_WAIT) {
-			print_status(svc->desc, STATUS_WAIT, false);
-
-			status = runsvc_wait(svc);
-
-			print_status(svc->desc,
-				     status == EXIT_SUCCESS ?
-				     STATUS_OK : STATUS_FAIL,
-				     true);
-			delsvc(svc);
-		} else {
-			svc->pid = runsvc(svc);
-			if (svc->pid == -1) {
-				print_status(svc->desc, STATUS_FAIL, false);
-				delsvc(svc);
-				continue;
-			}
-
-			if (svc->type == SVC_RESPAWN)
-				print_status(svc->desc, STATUS_STARTED, false);
-
-			svclist_add(svc);
-		}
-	}
-}
-
 static int read_msg(int fd, ti_msg_t *msg)
 {
 	ssize_t ret;
@@ -151,7 +67,7 @@ retry:
 	return 0;
 }
 
-static void handle_tellinit(int ti_sock)
+static void handle_tellinit(void)
 {
 	ti_msg_t msg;
 	int fd;
@@ -167,19 +83,31 @@ static void handle_tellinit(int ti_sock)
 
 	switch (msg.type) {
 	case TI_SHUTDOWN:
-		target = TGT_SHUTDOWN;
+		supervisor_set_target(TGT_SHUTDOWN);
 		break;
 	case TI_REBOOT:
-		target = TGT_REBOOT;
+		supervisor_set_target(TGT_REBOOT);
 		break;
 	}
 
 	close(fd);
 }
 
+void target_completed(int target)
+{
+	switch (target) {
+	case TGT_BOOT:
+		if (ti_sock == -1)
+			ti_sock = mksock(INITSOCK, SOCK_FLAG_ROOT_ONLY);
+		break;
+	default:
+		break;
+	}
+}
+
 int main(void)
 {
-	int ti_sock = -1, sfd, ret, count;
+	int ret, count;
 	struct pollfd pfd[2];
 
 	if (getpid() != 1) {
@@ -187,44 +115,35 @@ int main(void)
 		return EXIT_FAILURE;
 	}
 
-	if (svcscan(SVCDIR, &cfg, RDSVC_NO_EXEC | RDSVC_NO_CTTY)) {
-		fputs("Error reading service list from " SVCDIR "\n"
-			"Trying to continue anyway\n", stderr);
-	}
+	supervisor_init();
 
-	sfd = sigsetup();
-	if (sfd < 0)
+	sigfd = sigsetup();
+	if (sigfd < 0)
 		return -1;
 
-	memset(pfd, 0, sizeof(pfd));
-	pfd[0].fd = sfd;
-	pfd[0].events = POLLIN;
-	count = 1;
-
 	for (;;) {
-		if (!svclist_have_singleshot() && target != runlevel) {
-			start_runlevel(target);
-			runlevel = target;
-
-			if (target == TGT_BOOT && ti_sock == -1) {
-				ti_sock = mksock(INITSOCK, SOCK_FLAG_ROOT_ONLY);
-				if (ti_sock != -1) {
-					pfd[1].fd = ti_sock;
-					pfd[1].events = POLLIN;
-					count = 2;
-				}
-			}
-			continue;
+		while (supervisor_process_queues())
+			;
+
+		memset(pfd, 0, sizeof(pfd));
+		pfd[0].fd = sigfd;
+		pfd[0].events = POLLIN;
+		count = 1;
+
+		if (ti_sock != -1) {
+			pfd[1].fd = ti_sock;
+			pfd[1].events = POLLIN;
+			count = 2;
 		}
 
 		ret = poll(pfd, count, -1);
 
 		if (ret > 0) {
 			if (pfd[0].revents & POLLIN)
-				handle_signal(sfd);
+				handle_signal();
 
 			if (ti_sock != -1 && pfd[1].revents & POLLIN)
-				handle_tellinit(ti_sock);
+				handle_tellinit();
 		}
 	}
 
diff --git a/initd/runsvc.c b/initd/runsvc.c
index aba83b1..1b23cb6 100644
--- a/initd/runsvc.c
+++ b/initd/runsvc.c
@@ -49,18 +49,3 @@ pid_t runsvc(service_t *svc)
 
 	return pid;
 }
-
-int runsvc_wait(service_t *svc)
-{
-	pid_t ret, pid = runsvc(svc);
-	int status;
-
-	if (pid == -1)
-		return EXIT_FAILURE;
-
-	do {
-		ret = waitpid(pid, &status, 0);
-	} while (ret != pid);
-
-	return WIFEXITED(status) ? WEXITSTATUS(status) : EXIT_FAILURE;
-}
diff --git a/initd/supervisor.c b/initd/supervisor.c
new file mode 100644
index 0000000..f439f6d
--- /dev/null
+++ b/initd/supervisor.c
@@ -0,0 +1,182 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include "init.h"
+
+static service_list_t cfg;
+
+static int target = -1;
+static service_t *running = NULL;
+static service_t *terminated = NULL;
+static service_t *queue = NULL;
+static int singleshot = 0;
+static bool waiting = false;
+
+static int start_service(service_t *svc)
+{
+	svc->pid = runsvc(svc);
+	if (svc->pid == -1) {
+		print_status(svc->desc, STATUS_FAIL, false);
+		delsvc(svc);
+		return -1;
+	}
+
+	svc->next = running;
+	running = svc;
+	return 0;
+}
+
+static void handle_terminated_service(service_t *svc)
+{
+	switch (svc->type) {
+	case SVC_RESPAWN:
+		if (target == TGT_REBOOT || target == TGT_SHUTDOWN)
+			break;
+
+		if (svc->rspwn_limit > 0) {
+			svc->rspwn_limit -= 1;
+
+			if (svc->rspwn_limit == 0) {
+				print_status(svc->desc, STATUS_FAIL, false);
+				break;
+			}
+		}
+
+		start_service(svc);
+		return;
+	case SVC_WAIT:
+		waiting = false;
+		print_status(svc->desc,
+			     svc->status == EXIT_SUCCESS ?
+			     STATUS_OK : STATUS_FAIL, true);
+		if (singleshot == 0 && queue == NULL)
+			target_completed(target);
+		break;
+	case SVC_ONCE:
+		singleshot -= 1;
+		print_status(svc->desc,
+			     svc->status == EXIT_SUCCESS ?
+			     STATUS_OK : STATUS_FAIL, false);
+		if (singleshot == 0 && queue == NULL && !waiting)
+			target_completed(target);
+		break;
+	}
+	delsvc(svc);
+}
+
+void supervisor_handle_exited(pid_t pid, int status)
+{
+	service_t *prev = NULL, *svc = running;
+
+	while (svc != NULL && svc->pid != pid) {
+		prev = svc;
+		svc = svc->next;
+	}
+
+	if (svc == NULL)
+		return;
+
+	if (prev != NULL) {
+		prev->next = svc->next;
+	} else {
+		running = svc->next;
+	}
+
+	svc->status = status;
+	svc->next = terminated;
+	terminated = svc;
+}
+
+void supervisor_set_target(int next)
+{
+	service_t *svc;
+
+	if (target == TGT_REBOOT || target == TGT_SHUTDOWN || next == target)
+		return;
+
+	if (next == TGT_REBOOT || next == TGT_SHUTDOWN) {
+		while (queue != NULL) {
+			svc = queue;
+			queue = queue->next;
+			delsvc(svc);
+		}
+	}
+
+	if (queue != NULL) {
+		for (svc = queue; svc->next != NULL; svc = svc->next)
+			;
+		svc->next = cfg.targets[next];
+	} else {
+		queue = cfg.targets[next];
+	}
+
+	cfg.targets[next] = NULL;
+	target = next;
+}
+
+void supervisor_init(void)
+{
+	int status = STATUS_OK;
+
+	if (svcscan(SVCDIR, &cfg, RDSVC_NO_EXEC | RDSVC_NO_CTTY))
+		status = STATUS_FAIL;
+
+	target = TGT_BOOT;
+	queue = cfg.targets[TGT_BOOT];
+	cfg.targets[TGT_BOOT] = NULL;
+
+	print_status("reading configuration from " SVCDIR, status, false);
+}
+
+bool supervisor_process_queues(void)
+{
+	service_t *svc;
+
+	if (terminated != NULL) {
+		svc = terminated;
+		terminated = terminated->next;
+
+		handle_terminated_service(svc);
+		return true;
+	}
+
+	if (waiting || queue == NULL)
+		return false;
+
+	svc = queue;
+	queue = queue->next;
+
+	if (start_service(svc) != 0)
+		return true;
+
+	switch (svc->type) {
+	case SVC_WAIT:
+		print_status(svc->desc, STATUS_WAIT, false);
+		waiting = true;
+		break;
+	case SVC_RESPAWN:
+		print_status(svc->desc, STATUS_STARTED, false);
+		break;
+	case SVC_ONCE:
+		singleshot += 1;
+		break;
+	}
+
+	if (singleshot == 0 && queue == NULL && !waiting)
+		target_completed(target);
+	return true;
+}
diff --git a/initd/svclist.c b/initd/svclist.c
deleted file mode 100644
index 4ed897f..0000000
--- a/initd/svclist.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * Copyright (C) 2018 - David Oberhollenzer
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-#include "init.h"
-
-static service_t *running = NULL;	/* currently supervised services */
-static int singleshot = 0;		/* active singleshot services */
-
-bool svclist_have_singleshot(void)
-{
-	return singleshot > 0;
-}
-
-void svclist_add(service_t *svc)
-{
-	svc->next = running;
-	running = svc;
-
-	if (svc->type == SVC_ONCE)
-		singleshot += 1;
-}
-
-service_t *svclist_remove(pid_t pid)
-{
-	service_t *prev = NULL, *svc = running;
-
-	while (svc != NULL) {
-		if (svc->pid == pid) {
-			if (prev != NULL) {
-				prev->next = svc->next;
-			} else {
-				running = svc->next;
-			}
-			svc->next = NULL;
-
-			if (svc->type == SVC_ONCE)
-				singleshot -= 1;
-			break;
-		}
-
-		prev = svc;
-		svc = svc->next;
-	}
-
-	return svc;
-}