libcamera: mediadevice: Fix graph parsing error handling

Most errors recorded during graph parsing are logged but not propagated
to the caller. Fix this and delete objects that are created but not
successfully added to the graph to avoid memory leaks. As the error code
returned from the addObject() and populate*() functions doesn't matter
much, turn them into bool functions.

Additionally, add a way to query whether the media graph was valid, and
clear objects before populating the graph to avoid leaking them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

2 files changed, 53 insertions, 32 deletions

diff --git a/src/libcamera/include/media_device.h b/src/libcamera/include/media_device.h
index bca7c9a1..74a67c81 100644
--- a/src/libcamera/include/media_device.h
+++ b/src/libcamera/include/media_device.h
@@ -28,6 +28,7 @@ public:
 	void close();
 
 	int populate();
+	bool valid() const { return valid_; }
 
 	const std::string driver() const { return driver_; }
 	const std::string devnode() const { return devnode_; }
@@ -37,18 +38,19 @@ private:
 	std::string driver_;
 	std::string devnode_;
 	int fd_;
+	bool valid_;
 
 	std::map<unsigned int, MediaObject *> objects_;
 	MediaObject *object(unsigned int id);
-	int addObject(MediaObject *obj);
+	bool addObject(MediaObject *obj);
 	void clear();
 
 	std::vector<MediaEntity *> entities_;
 	MediaEntity *getEntityByName(const std::string &name);
 
-	void populateEntities(const struct media_v2_topology &topology);
-	int populatePads(const struct media_v2_topology &topology);
-	int populateLinks(const struct media_v2_topology &topology);
+	bool populateEntities(const struct media_v2_topology &topology);
+	bool populatePads(const struct media_v2_topology &topology);
+	bool populateLinks(const struct media_v2_topology &topology);
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
index d9a5196a..fd5a3174 100644
--- a/src/libcamera/media_device.cpp
+++ b/src/libcamera/media_device.cpp
@@ -56,7 +56,7 @@ namespace libcamera {
  * \param devnode The media device node path
  */
 MediaDevice::MediaDevice(const std::string &devnode)
-	: devnode_(devnode), fd_(-1)
+	: devnode_(devnode), fd_(-1), valid_(false)
 {
 }
 
@@ -99,6 +99,7 @@ void MediaDevice::clear()
 
 	objects_.clear();
 	entities_.clear();
+	valid_ = false;
 }
 
 /**
@@ -163,18 +164,18 @@ void MediaDevice::close()
  * Add a new object to the global objects pool and fail if the object
  * has already been registered.
  */
-int MediaDevice::addObject(MediaObject *obj)
+bool MediaDevice::addObject(MediaObject *obj)
 {
 
 	if (objects_.find(obj->id()) != objects_.end()) {
 		LOG(Error) << "Element with id " << obj->id()
 			   << " already enumerated.";
-		return -EEXIST;
+		return false;
 	}
 
 	objects_[obj->id()] = obj;
 
-	return 0;
+	return true;
 }
 
 /*
@@ -201,7 +202,7 @@ MediaEntity *MediaDevice::getEntityByName(const std::string &name)
 	return nullptr;
 }
 
-int MediaDevice::populateLinks(const struct media_v2_topology &topology)
+bool MediaDevice::populateLinks(const struct media_v2_topology &topology)
 {
 	media_v2_link *mediaLinks = reinterpret_cast<media_v2_link *>
 				    (topology.ptr_links);
@@ -222,7 +223,7 @@ int MediaDevice::populateLinks(const struct media_v2_topology &topology)
 		if (!source) {
 			LOG(Error) << "Failed to find pad with id: "
 				   << source_id;
-			return -ENODEV;
+			return false;
 		}
 
 		unsigned int sink_id = mediaLinks[i].sink_id;
@@ -231,20 +232,23 @@ int MediaDevice::populateLinks(const struct media_v2_topology &topology)
 		if (!sink) {
 			LOG(Error) << "Failed to find pad with id: "
 				   << sink_id;
-			return -ENODEV;
+			return false;
 		}
 
 		MediaLink *link = new MediaLink(&mediaLinks[i], source, sink);
+		if (!addObject(link)) {
+			delete link;
+			return false;
+		}
+
 		source->addLink(link);
 		sink->addLink(link);
-
-		addObject(link);
 	}
 
-	return 0;
+	return true;
 }
 
-int MediaDevice::populatePads(const struct media_v2_topology &topology)
+bool MediaDevice::populatePads(const struct media_v2_topology &topology)
 {
 	media_v2_pad *mediaPads = reinterpret_cast<media_v2_pad *>
 				  (topology.ptr_pads);
@@ -258,16 +262,19 @@ int MediaDevice::populatePads(const struct media_v2_topology &topology)
 		if (!mediaEntity) {
 			LOG(Error) << "Failed to find entity with id: "
 				   << entity_id;
-			return -ENODEV;
+			return false;
 		}
 
 		MediaPad *pad = new MediaPad(&mediaPads[i], mediaEntity);
-		mediaEntity->addPad(pad);
+		if (!addObject(pad)) {
+			delete pad;
+			return false;
+		}
 
-		addObject(pad);
+		mediaEntity->addPad(pad);
 	}
 
-	return 0;
+	return true;
 }
 
 /*
@@ -275,17 +282,22 @@ int MediaDevice::populatePads(const struct media_v2_topology &topology)
  * reference in the MediaObject global pool and in the global vector of
  * entities.
  */
-void MediaDevice::populateEntities(const struct media_v2_topology &topology)
+bool MediaDevice::populateEntities(const struct media_v2_topology &topology)
 {
 	media_v2_entity *mediaEntities = reinterpret_cast<media_v2_entity *>
 					 (topology.ptr_entities);
 
 	for (unsigned int i = 0; i < topology.num_entities; ++i) {
 		MediaEntity *entity = new MediaEntity(&mediaEntities[i]);
+		if (!addObject(entity)) {
+			delete entity;
+			return false;
+		}
 
-		addObject(entity);
 		entities_.push_back(entity);
 	}
+
+	return true;
 }
 
 /**
@@ -311,6 +323,8 @@ int MediaDevice::populate()
 	__u64 version = -1;
 	int ret;
 
+	clear();
+
 	/*
 	 * Keep calling G_TOPOLOGY until the version number stays stable.
 	 */
@@ -343,25 +357,30 @@ int MediaDevice::populate()
 	}
 
 	/* Populate entities, pads and links. */
-	populateEntities(topology);
-
-	ret = populatePads(topology);
-	if (ret)
-		goto error_free_objs;
-
-	ret = populateLinks(topology);
-error_free_objs:
-	if (ret)
-		clear();
+	if (populateEntities(topology) &&
+	    populatePads(topology) &&
+	    populateLinks(topology))
+		valid_ = true;
 
 	delete[] links;
 	delete[] ents;
 	delete[] pads;
 
-	return ret;
+	if (!valid_) {
+		clear();
+		return -EINVAL;
+	}
+
+	return 0;
 }
 
 /**
+ * \fn MediaDevice::valid()
+ * \brief Query whether the media graph is valid
+ * \return true if the media graph is valid, false otherwise
+ */
+
+/**
  * \var MediaDevice::objects_
  * \brief Global map of media objects (entities, pads, links) keyed by their
  * object id.