colin/wireplumber
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

transition: ensure single completion and finish

Browse Source 
At the moment, the same transition can be completed multiple times
(assuming sufficiently high reference count):

  return_error()
  finish()
  return_error()

The consequence of that is that the transition closure will be
invoked multiple times. This is unexpected.

Add some guards against completing a transition or calling finish()
multiple times.

Fixes #628
This commit is contained in:
Barnabás Pőcze
2024-05-18 00:53:33 +02:00
parent 1ddfbc532c
commit 89b6766cd6
1 changed files with 28 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
lib/wp/transition.c
View File

@@ -66,6 +66,8 @@ struct _WpTransitionPrivate
/* state machine */
gboolean started;
gboolean completed;
gboolean finished;
guint step;
GError *error;
};
@@ -348,8 +350,7 @@ wp_transition_get_completed (WpTransition * self)
g_return_val_if_fail (WP_IS_TRANSITION (self), FALSE);
WpTransitionPrivate *priv = wp_transition_get_instance_private (self);
return (priv->step == WP_TRANSITION_STEP_NONE && priv->started) ||
priv->step == WP_TRANSITION_STEP_ERROR;
return priv->completed;
}
/*!
@@ -370,6 +371,8 @@ wp_transition_had_error (WpTransition * self)
static void
wp_transition_return (WpTransition * self, WpTransitionPrivate *priv)
{
g_assert (priv->completed);
if (priv->closure) {
GValue values[2] = { G_VALUE_INIT, G_VALUE_INIT };
g_value_init (&values[0], G_TYPE_OBJECT);
@@ -427,6 +430,11 @@ wp_transition_advance (WpTransition * self)
guint next_step;
GError *error = NULL;
if (priv->completed) {
wp_warning_object (priv->source_object, "tried to advance completed transition");
return;
}
priv->started = TRUE;
if (g_cancellable_set_error_if_cancelled (priv->cancellable, &error)) {
@@ -442,17 +450,20 @@ wp_transition_advance (WpTransition * self)
if (next_step == WP_TRANSITION_STEP_ERROR) {
/* return error if the callback didn't do it already */
if (G_UNLIKELY (!priv->error)) {
if (G_UNLIKELY (!priv->completed)) {
wp_transition_return_error (self, g_error_new (WP_DOMAIN_LIBRARY,
WP_LIBRARY_ERROR_INVARIANT, "state machine error"));
}
return;
}
g_assert (!priv->completed);
/* if we reached STEP_NONE again, that means we reached the next state */
if (next_step == WP_TRANSITION_STEP_NONE) {
/* complete the transition */
priv->step = next_step;
priv->completed = TRUE;
wp_transition_return (self, priv);
return;
}
@@ -490,15 +501,16 @@ wp_transition_return_error (WpTransition * self, GError * error)
/* don't allow _return_error() to be called multiple times,
as it is dangerous to recurse in execute_step() */
if (G_UNLIKELY (priv->error)) {
wp_warning_object (self, "transition bailing out multiple times; "
"new error is: %s", error->message);
if (G_UNLIKELY (priv->completed)) {
wp_warning_object (priv->source_object,
"tried to set error on completed transition: %s", error->message);
g_error_free (error);
return;
}
priv->step = WP_TRANSITION_STEP_ERROR;
priv->error = error;
priv->completed = TRUE;
/* allow the implementation to rollback changes */
if (WP_TRANSITION_GET_CLASS (self)->execute_step)
@@ -535,8 +547,18 @@ wp_transition_finish (GAsyncResult * res, GError ** error)
priv->step = WP_TRANSITION_STEP_ERROR;
g_propagate_error (error, g_error_new (WP_DOMAIN_LIBRARY,
WP_LIBRARY_ERROR_INVARIANT, "finished before starting"));
} else if (!priv->completed) {
priv->step = WP_TRANSITION_STEP_ERROR;
g_propagate_error (error, g_error_new (WP_DOMAIN_LIBRARY,
WP_LIBRARY_ERROR_INVARIANT, "finished before completion"));
} else if (priv->finished) {
priv->step = WP_TRANSITION_STEP_ERROR;
g_propagate_error (error, g_error_new (WP_DOMAIN_LIBRARY,
WP_LIBRARY_ERROR_INVARIANT, "finished multiple times"));
}
priv->finished = TRUE;
wp_trace_object (priv->source_object, "transition: finished %s",
(priv->step == WP_TRANSITION_STEP_NONE) ? "ok" : "with error");