libcamera: media_device: Open and close media device inside populate()

Remove the need for the caller to open and close the media device when
populating the MediaDevice. This is done as an effort to make the usage
of the MediaDevice less error prone and the interface stricter.

The rework also revealed and fixes a potential memory leak in
MediaDevice::populate() where resources would not be deleted if the
second MEDIA_IOC_G_TOPOLOGY would fail.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/device_enumerator.cpp

@@ -207,11 +207,7 @@ int DeviceEnumerator::addDevice(const std::string &deviceNode)
 {
 	std::shared_ptr<MediaDevice> media = std::make_shared<MediaDevice>(deviceNode);
 
-	int ret = media->open();
-	if (ret < 0)
-		return ret;
-
-	ret = media->populate();
+	int ret = media->populate();
 	if (ret < 0) {
 		LOG(DeviceEnumerator, Info)
 			<< "Unable to populate media device " << deviceNode
@@ -238,8 +234,6 @@ int DeviceEnumerator::addDevice(const std::string &deviceNode)
 			return ret;
 	}
 
-	media->close();
-
 	LOG(DeviceEnumerator, Debug)
 		<< "Added device " << deviceNode << ": " << media->driver();
 

src/libcamera/media_device.cpp

@@ -221,6 +221,10 @@ int MediaDevice::populate()
 
 	clear();
 
+	ret = open();
+	if (ret)
+		return ret;
+
 	/*
 	 * Keep calling G_TOPOLOGY until the version number stays stable.
 	 */
@@ -237,7 +241,7 @@ int MediaDevice::populate()
 			LOG(MediaDevice, Error)
 				<< "Failed to enumerate topology: "
 				<< strerror(-ret);
-			return ret;
+			goto done;
 		}
 
 		if (version == topology.topology_version)
@@ -262,6 +266,10 @@ int MediaDevice::populate()
 	    populateLinks(topology))
 		valid_ = true;
 
+	ret = 0;
+done:
+	close();
+
 	delete[] ents;
 	delete[] interfaces;
 	delete[] pads;
@@ -272,7 +280,7 @@ int MediaDevice::populate()
 		return -EINVAL;
 	}
 
-	return 0;
+	return ret;
 }
 
 /**