reserve: wrap device reservation monitor reference implementation

src/modules/reserve-monitor.c

@@ -0,0 +1,259 @@
+/***
+  Copyright 2009 Lennart Poettering
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+***/
+
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "reserve-monitor.h"
+
+struct rm_monitor {
+	int ref;
+
+	char *device_name;
+	char *service_name;
+
+	DBusConnection *connection;
+
+	unsigned busy:1;
+	unsigned filtering:1;
+	unsigned matching:1;
+
+	rm_change_cb_t change_cb;
+	void *userdata;
+};
+
+#define SERVICE_PREFIX "org.freedesktop.ReserveDevice1."
+
+static DBusHandlerResult filter_handler(
+	DBusConnection *c,
+	DBusMessage *s,
+	void *userdata) {
+
+	DBusMessage *reply;
+	rm_monitor *m;
+	DBusError error;
+
+	dbus_error_init(&error);
+
+	m = userdata;
+	assert(m->ref >= 1);
+
+	if (dbus_message_is_signal(s, "org.freedesktop.DBus", "NameOwnerChanged")) {
+		const char *name, *old, *new;
+
+		if (!dbus_message_get_args(
+			    s,
+			    &error,
+			    DBUS_TYPE_STRING, &name,
+			    DBUS_TYPE_STRING, &old,
+			    DBUS_TYPE_STRING, &new,
+			    DBUS_TYPE_INVALID))
+			goto invalid;
+
+		if (strcmp(name, m->service_name) == 0) {
+
+			m->busy = !!(new && *new);
+
+			if (m->change_cb) {
+				m->ref++;
+				m->change_cb(m);
+				rm_release(m);
+			}
+		}
+	}
+
+	return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+
+invalid:
+	if (!(reply = dbus_message_new_error(
+		      s,
+		      DBUS_ERROR_INVALID_ARGS,
+		      "Invalid arguments")))
+		goto oom;
+
+	if (!dbus_connection_send(c, reply, NULL))
+		goto oom;
+
+	dbus_message_unref(reply);
+
+	dbus_error_free(&error);
+
+	return DBUS_HANDLER_RESULT_HANDLED;
+
+oom:
+	if (reply)
+		dbus_message_unref(reply);
+
+	dbus_error_free(&error);
+
+	return DBUS_HANDLER_RESULT_NEED_MEMORY;
+}
+
+int rm_watch(
+	rm_monitor **_m,
+	DBusConnection *connection,
+	const char*device_name,
+	rm_change_cb_t change_cb,
+	DBusError *error)  {
+
+	rm_monitor *m = NULL;
+	int r;
+	DBusError _error;
+
+	if (!error)
+		error = &_error;
+
+	dbus_error_init(error);
+
+	if (!_m)
+		return -EINVAL;
+
+	if (!connection)
+		return -EINVAL;
+
+	if (!device_name)
+		return -EINVAL;
+
+	if (!(m = calloc(sizeof(rm_monitor), 1)))
+		return -ENOMEM;
+
+	m->ref = 1;
+
+	if (!(m->device_name = strdup(device_name))) {
+		r = -ENOMEM;
+		goto fail;
+	}
+
+	m->connection = dbus_connection_ref(connection);
+	m->change_cb = change_cb;
+
+	if (!(m->service_name = malloc(sizeof(SERVICE_PREFIX) + strlen(device_name)))) {
+		r = -ENOMEM;
+		goto fail;
+	}
+	sprintf(m->service_name, SERVICE_PREFIX "%s", m->device_name);
+
+	if (!(dbus_connection_add_filter(m->connection, filter_handler, m, NULL))) {
+		r = -ENOMEM;
+		goto fail;
+	}
+
+	m->filtering = 1;
+
+	dbus_bus_add_match(m->connection,
+			   "type='signal',"
+			   "sender='" DBUS_SERVICE_DBUS "',"
+			   "interface='" DBUS_INTERFACE_DBUS "',"
+			   "member='NameOwnerChanged'", error);
+
+	if (dbus_error_is_set(error)) {
+		r = -EIO;
+		goto fail;
+	}
+
+	m->matching = 1;
+
+	m->busy = dbus_bus_name_has_owner(m->connection, m->service_name, error);
+
+	if (dbus_error_is_set(error)) {
+		r = -EIO;
+		goto fail;
+	}
+
+	*_m = m;
+	return 0;
+
+fail:
+	if (&_error == error)
+		dbus_error_free(&_error);
+
+	if (m)
+		rm_release(m);
+
+	return r;
+}
+
+void rm_release(rm_monitor *m) {
+	if (!m)
+		return;
+
+	assert(m->ref > 0);
+
+	if (--m->ref > 0)
+		return;
+
+	if (m->matching)
+		dbus_bus_remove_match(
+			m->connection,
+			"type='signal',"
+			"sender='" DBUS_SERVICE_DBUS "',"
+			"interface='" DBUS_INTERFACE_DBUS "',"
+			"member='NameOwnerChanged'", NULL);
+
+	if (m->filtering)
+		dbus_connection_remove_filter(
+			m->connection,
+			filter_handler,
+			m);
+
+	free(m->device_name);
+	free(m->service_name);
+
+	if (m->connection)
+		dbus_connection_unref(m->connection);
+
+	free(m);
+}
+
+int rm_busy(rm_monitor *m) {
+	if (!m)
+		return -EINVAL;
+
+	assert(m->ref > 0);
+
+	return m->busy;
+}
+
+void rm_set_userdata(rm_monitor *m, void *userdata) {
+
+	if (!m)
+		return;
+
+	assert(m->ref > 0);
+	m->userdata = userdata;
+}
+
+void* rm_get_userdata(rm_monitor *m) {
+
+	if (!m)
+		return NULL;
+
+	assert(m->ref > 0);
+
+	return m->userdata;
+}