session-helper: Improve HostCommand life-cycle handling

Add flag that instructs the session-helper to kill
the spawned command when the caller drops off the bus.

Closes: #2326

Closes: #2365
Approved by: alexlarsson

common/flatpak-utils-private.h

@@ -39,6 +39,7 @@
 
 typedef enum {
  FLATPAK_HOST_COMMAND_FLAGS_CLEAR_ENV = 1 << 0,
+ FLATPAK_HOST_COMMAND_FLAGS_WATCH_BUS = 1 << 1,
 } FlatpakHostCommandFlags;
 
 

session-helper/flatpak-session-helper.c

@@ -56,6 +56,7 @@ typedef struct
  GPid pid;
  char *client;
  guint child_watch;
+ gboolean watch_bus;
 } PidData;
 
 static void
@@ -237,7 +238,8 @@ handle_host_command (FlatpakDevelopment *object,
 
  if (!g_variant_is_of_type (arg_fds, G_VARIANT_TYPE ("a{uh}")) ||
  !g_variant_is_of_type (arg_envs, G_VARIANT_TYPE ("a{ss}")) ||
- (flags & ~FLATPAK_HOST_COMMAND_FLAGS_CLEAR_ENV) != 0)
+ (flags & ~(FLATPAK_HOST_COMMAND_FLAGS_CLEAR_ENV|
+ FLATPAK_HOST_COMMAND_FLAGS_WATCH_BUS)) != 0)
  {
  g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
  G_DBUS_ERROR_INVALID_ARGS,
@@ -353,6 +355,7 @@ handle_host_command (FlatpakDevelopment *object,
  pid_data = g_new0 (PidData, 1);
  pid_data->pid = pid;
  pid_data->client = g_strdup (g_dbus_method_invocation_get_sender (invocation));
+ pid_data->watch_bus = (flags & FLATPAK_HOST_COMMAND_FLAGS_WATCH_BUS) != 0;
  pid_data->child_watch = g_child_watch_add_full (G_PRIORITY_DEFAULT,
  pid,
  child_watch_died,
@@ -401,6 +404,48 @@ handle_host_command_signal (FlatpakDevelopment *object,
  return TRUE;
 }
 
+static void
+name_owner_changed (GDBusConnection *connection,
+ const gchar *sender_name,
+ const gchar *object_path,
+ const gchar *interface_name,
+ const gchar *signal_name,
+ GVariant *parameters,
+ gpointer user_data)
+{
+ const char *name, *from, *to;
+
+ g_variant_get (parameters, "(&s&s&s)", &name, &from, &to);
+
+ if (name[0] == ':' &&
+ strcmp (name, from) == 0 &&
+ strcmp (to, "") == 0)
+ {
+ GHashTableIter iter;
+ PidData *pid_data = NULL;
+ GList *list = NULL, *l;
+
+ g_hash_table_iter_init (&iter, client_pid_data_hash);
+ while (g_hash_table_iter_next (&iter, NULL, (gpointer *)pid_data))
+ {
+ if (pid_data->watch_bus && g_str_equal (pid_data->client, name))
+ list = g_list_prepend (list, pid_data);
+ }
+
+ for (l = list; l; l = l->next)
+ {
+ pid_data = l->data;
+ killpg (pid_data->pid, SIGINT);
+ }
+
+ g_list_free (list);
+ }
+}
+
+#define DBUS_NAME_DBUS "org.freedesktop.DBus"
+#define DBUS_INTERFACE_DBUS DBUS_NAME_DBUS
+#define DBUS_PATH_DBUS "/org/freedesktop/DBus"
+
 static void
 on_bus_acquired (GDBusConnection *connection,
  const gchar *name,
@@ -410,6 +455,16 @@ on_bus_acquired (GDBusConnection *connection,
  FlatpakDevelopment *devel;
  GError *error = NULL;
 
+ g_dbus_connection_signal_subscribe (connection,
+ DBUS_NAME_DBUS,
+ DBUS_INTERFACE_DBUS,
+ "NameOwnerChanged",
+ DBUS_PATH_DBUS,
+ NULL,
+ G_DBUS_SIGNAL_FLAGS_NONE,
+ name_owner_changed,
+ NULL, NULL);
+
  helper = flatpak_session_helper_skeleton_new ();
 
  flatpak_session_helper_set_version (FLATPAK_SESSION_HELPER (helper), 1);