initd: restructure and merge service supervision code

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

1 files changed, 182 insertions, 0 deletions

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;
+}