From: Aleš <ales.mrazek@nic.cz>
Date: Mon, 3 Aug 2020 13:06:59 +0000 (+0200)
Subject: watcher: sdbus module to control  processes
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=706b8a34b506c768b5c764490d55064a15d13a8f;p=thirdparty%2Fknot-resolver.git

watcher: sdbus module to control  processes
---

diff --git a/utils/watcher/dbus_control.c b/utils/watcher/dbus_control.c
new file mode 100644
index 000000000..ccba9074a
--- /dev/null
+++ b/utils/watcher/dbus_control.c
@@ -0,0 +1,166 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <systemd/sd-bus.h>
+
+#include "contrib/ccan/asprintf/asprintf.h"
+#include "dbus_control.h"
+
+#define DBUS_NAME_SYSTEMD   "org.freedesktop.systemd1"
+/* DBus services paths. */
+#define DBUS_PATH_SYSTEMD   "/org/freedesktop/systemd1"
+#define DBUS_PATH_KRESD     DBUS_PATH_SYSTEMD"/unit/kresd_40%s_2eservice"
+#define DBUS_PATH_GC        DBUS_PATH_SYSTEMD"/unit/kres_2dcache_2dgc_2eservice"
+/* DBus interfaces. */
+#define DBUS_INTF_BASE      "org.freedesktop"
+#define DBUS_INTR_MAN       DBUS_INTF_BASE".systemd1.Manager"
+#define DBUS_INTR_PROP      DBUS_INTF_BASE".DBus.Properties"
+#define DBUS_INTR_UNIT      DBUS_INTF_BASE".systemd1.Unit"
+/* Services names. */
+#define SERVICE_KRESD       "kresd@%s.service"
+#define SERVICE_CACHE_GC    "kres-cache-gc.service"
+
+
+/* Convert method_t(enum) to string. */
+static const char *strmethod(method_t method)
+{
+	static const char *method_string[] = {
+		"StartUnit",
+		"StopUnit",
+		"RestartUnit",
+		"ReloadUnit"
+	};
+	return method_string[method];
+}
+
+void dbus_clean(void)
+{
+	sd_bus* bus = NULL;
+	sd_bus_default_system(&bus);
+	sd_bus_flush(bus);
+	sd_bus_close(bus);
+}
+
+int kresd_status(const char *instance, char **status)
+{
+	sd_bus* bus = NULL;
+	void* userdata = NULL;
+	char *instance_service;
+	sd_bus_error err = SD_BUS_ERROR_NULL;
+
+	int ret = sd_bus_default_system(&bus);
+
+	asprintf(&instance_service, DBUS_PATH_KRESD, instance);
+
+	ret = sd_bus_get_property_string(
+		bus,
+		DBUS_NAME_SYSTEMD,
+		instance_service,
+		DBUS_INTR_UNIT,
+		"ActiveState",
+		&err,
+		status
+	);
+	free(instance_service);
+
+	return ret;
+}
+
+int cache_gc_status(char **status)
+{
+	sd_bus* bus = NULL;
+	void* userdata = NULL;
+	sd_bus_error err = SD_BUS_ERROR_NULL;
+
+	int ret = sd_bus_default_system(&bus);
+
+	ret = sd_bus_get_property_string(
+		bus,
+		DBUS_NAME_SYSTEMD,
+		DBUS_PATH_GC,
+		DBUS_INTR_UNIT,
+		"ActiveState",
+		&err,
+		status
+	);
+	return ret;
+}
+
+int kresd_control(method_t method, const char *instance)
+{
+	sd_bus* bus = NULL;
+	sd_bus_message *reply = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	char *instance_service;
+	const char *unit_method = strmethod(method);
+	asprintf(&instance_service, SERVICE_KRESD, instance);
+
+	int ret = sd_bus_default_system(&bus);
+
+	ret = sd_bus_call_method(
+		bus,
+		DBUS_NAME_SYSTEMD,
+		DBUS_PATH_SYSTEMD,
+		DBUS_INTR_MAN,
+		unit_method,
+		&error, &reply,
+		"ss",
+		instance_service,
+		"replace"
+	);
+
+	if (ret < 0) {
+		printf(
+			"[sdbus] failed to issue method call '%s' %s: %s\n",
+			strmethod(method), instance_service, error.message);
+		goto cleanup;
+	}
+
+	printf("[sdbus] %s %s\n", strmethod(method), instance_service);
+
+	cleanup:
+	free(instance_service);
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(reply);
+
+	return ret;
+}
+
+int cache_gc_control(method_t method)
+{
+	sd_bus* bus = NULL;
+	sd_bus_message *reply = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	const char *unit_method = strmethod(method);
+
+	int ret = sd_bus_default_system(&bus);
+
+	ret = sd_bus_call_method(
+		bus,
+		DBUS_NAME_SYSTEMD,
+		DBUS_PATH_SYSTEMD,
+		DBUS_INTR_MAN,
+		unit_method,
+		&error,
+		&reply,
+		"ss",
+		SERVICE_CACHE_GC,
+		"replace"
+	);
+
+	if (ret < 0) {
+		printf(
+			"[sdbus] failed to issue method call '%s' %s: %s\n",
+			unit_method, SERVICE_CACHE_GC, error.message);
+		goto cleanup;
+	}
+
+	printf("[sdbus] %s %s\n", unit_method, SERVICE_CACHE_GC);
+
+	cleanup:
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(reply);
+
+	return ret;
+}
\ No newline at end of file
diff --git a/utils/watcher/dbus_control.h b/utils/watcher/dbus_control.h
new file mode 100644
index 000000000..e3b1136d9
--- /dev/null
+++ b/utils/watcher/dbus_control.h
@@ -0,0 +1,27 @@
+#pragma once
+
+#include <systemd/sd-bus.h>
+
+
+/** Enumeration of operations, that can be used to control units(services). */
+typedef enum method_e {
+	UNIT_START,     /** Start unit(service). */
+	UNIT_STOP,      /** Stop unit(service). */
+	UNIT_RESTART,   /** Restart unit(service). */
+	UNIT_RELOAD     /** Reload unit(service). */
+} method_t;
+
+/** Cleans all unclosed DBus connections. */
+void dbus_clean(void);
+
+/** Get status of specific kresd instance. */
+int kresd_status(const char *instance, char **status);
+
+/** Get status of cache garbage collector. */
+int cache_gc_status(char **status);
+
+/** Control specific kresd instance. */
+int kresd_control(method_t method, const char *instance);
+
+/** Control cache garbage collector. */
+int cache_gc_control(method_t method);