[Spice-devel] [vdagent-linux v1] systemd-login: check for LockedHint property

[Victor Toso]

Property introduced in v230 of systemd.

Systems that don't have up to date systemd-login will get the
following log message:

"Properties.Get failed: Unknown property or interface."

Resolves: rhbz#1323623
---
 src/systemd-login.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 95 insertions(+), 7 deletions(-)

diff --git a/src/systemd-login.c b/src/systemd-login.c
index 730547a..c56fca4 100644
--- a/src/systemd-login.c
+++ b/src/systemd-login.c
@@ -36,14 +36,21 @@ struct session_info {
         char *match_session_signals;
     } dbus;
     gboolean session_is_locked;
+    gboolean session_locked_hint;
 };
 
+#define LOGIND_INTERFACE            "org.freedesktop.login1"
+
 #define LOGIND_SESSION_INTERFACE    "org.freedesktop.login1.Session"
 #define LOGIND_SESSION_OBJ_TEMPLATE "/org/freedesktop/login1/session/_3%s"
 
+#define DBUS_PROPERTIES_INTERFACE   "org.freedesktop.DBus.Properties"
+
 #define SESSION_SIGNAL_LOCK         "Lock"
 #define SESSION_SIGNAL_UNLOCK       "Unlock"
 
+#define SESSION_PROP_LOCKED_HINT    "LockedHint"
+
 /* dbus related */
 static DBusConnection *si_dbus_get_system_bus(void)
 {
@@ -112,6 +119,84 @@ static void si_dbus_match_rule_update(struct session_info *si)
 }
 
 static void
+si_dbus_read_properties(struct session_info *si)
+{
+    dbus_bool_t locked_hint, ret;
+    DBusMessageIter iter, iter_variant;
+    gint type;
+    DBusError error;
+    DBusMessage *message = NULL;
+    DBusMessage *reply = NULL;
+    gchar *session_object;
+    const gchar *interface, *property;
+
+    if (si->session == NULL)
+        return;
+
+    session_object = g_strdup_printf(LOGIND_SESSION_OBJ_TEMPLATE, si->session);
+    message = dbus_message_new_method_call(LOGIND_INTERFACE,
+                                           session_object,
+                                           DBUS_PROPERTIES_INTERFACE,
+                                           "Get");
+    g_free (session_object);
+    if (message == NULL) {
+        syslog(LOG_ERR, "Unable to create dbus message");
+        goto exit;
+    }
+
+    interface = LOGIND_SESSION_INTERFACE;
+    property = SESSION_PROP_LOCKED_HINT;
+    ret = dbus_message_append_args(message,
+                                   DBUS_TYPE_STRING, &interface,
+                                   DBUS_TYPE_STRING, &property,
+                                   DBUS_TYPE_INVALID);
+    if (!ret) {
+        syslog(LOG_ERR, "Unable to request locked-hint");
+        goto exit;
+    }
+
+    dbus_error_init(&error);
+    reply = dbus_connection_send_with_reply_and_block(si->dbus.system_connection,
+                                                      message,
+                                                      -1,
+                                                      &error);
+    if (reply == NULL || dbus_error_is_set(&error)) {
+        if (dbus_error_is_set(&error)) {
+            syslog(LOG_ERR, "Properties.Get failed: %s", error.message);
+            dbus_error_free(&error);
+        } else {
+            syslog(LOG_ERR, "Properties.Get failed");
+        }
+        goto exit;
+    }
+
+    dbus_message_iter_init(reply, &iter);
+    type = dbus_message_iter_get_arg_type(&iter);
+    if (type != DBUS_TYPE_VARIANT) {
+        syslog(LOG_ERR, "expected a variant, got a '%c' instead", type);
+        goto exit;
+    }
+
+    dbus_message_iter_recurse(&iter, &iter_variant);
+    type = dbus_message_iter_get_arg_type(&iter_variant);
+    if (type != DBUS_TYPE_BOOLEAN) {
+        syslog(LOG_ERR, "expected a boolean, got a '%c' instead", type);
+        goto exit;
+    }
+    dbus_message_iter_get_basic(&iter_variant, &locked_hint);
+
+    si->session_locked_hint = (locked_hint) ? TRUE : FALSE;
+exit:
+    if (reply != NULL) {
+        dbus_message_unref(reply);
+    }
+
+    if (message != NULL) {
+        dbus_message_unref(message);
+    }
+}
+
+static void
 si_dbus_read_signals(struct session_info *si)
 {
     DBusMessage *message = NULL;
@@ -220,16 +305,19 @@ char *session_info_session_for_pid(struct session_info *si, uint32_t pid)
 
 gboolean session_info_session_is_locked(struct session_info *si)
 {
-    g_return_val_if_fail (si != NULL, FALSE);
+    gboolean locked;
 
-    /* We could also rely on IdleHint property from Session which seems to work
-     * well in rhel7 but it wasn't working well in my own system (F23). I'm
-     * convinced for now that Lock/Unlock signals should be enough but that
-     * means Lock/Unlock being done by logind. That might take a while.
-     * Check: https://bugzilla.gnome.org/show_bug.cgi?id=764773 */
+    g_return_val_if_fail (si != NULL, FALSE);
 
     si_dbus_read_signals(si);
-    return si->session_is_locked;
+    si_dbus_read_properties(si);
+
+    locked = (si->session_is_locked || si->session_locked_hint);
+    if (si->verbose) {
+        syslog(LOG_DEBUG, "(systemd-login) session is locked: %s",
+               locked ? "yes" : "no");
+    }
+    return locked;
 }
 
 /* This function should only be called after session_info_get_active_session
-- 
2.5.5