117 lines
2.8 KiB
C++
117 lines
2.8 KiB
C++
/*
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* \brief Representation of an open file system node within the component
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* \author Christian Prochaska
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* \date 2017-06-09
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*/
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/*
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* Copyright (C) 2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _OPEN_NODE_H_
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#define _OPEN_NODE_H_
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/* Genode includes */
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#include <file_system/listener.h>
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#include <file_system_session/file_system_session.h>
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namespace File_system {
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/*
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* \param NODE component-specific node type
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*/
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template <typename NODE> class Open_node;
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}
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template <typename NODE>
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class File_system::Open_node : public File_system::Node
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{
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private:
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Genode::Id_space<File_system::Node>::Element _element;
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Genode::Weak_ptr<NODE> _node;
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Genode::Constructible<File_system::Listener> _listener { };
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Listener::Version const _version_when_opened { _node_version(_node) };
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/*
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* Flag to track whether the underlying file-system node was
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* modified via this 'Open_node'. That is, if closing the 'Open_node'
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* should notify listeners of the file.
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*/
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bool _was_written = false;
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static Listener::Version const _node_version(Genode::Weak_ptr<NODE> node)
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{
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Genode::Locked_ptr<NODE> locked_node { node };
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if (locked_node.valid())
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return locked_node->curr_version();
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else
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return Listener::Version { 0 };
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}
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public:
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Open_node(Genode::Weak_ptr<NODE> node,
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Genode::Id_space<File_system::Node> &id_space)
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: _element(*this, id_space), _node(node) { }
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~Open_node()
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{
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Genode::Locked_ptr<NODE> node { _node };
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if (_listener.constructed()) {
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if (node.valid())
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node->remove_listener(&*_listener);
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_listener.destruct();
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}
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/*
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* Notify remaining listeners about the changed file
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*/
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if (_was_written && node.valid()) {
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node->notify_listeners();
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}
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}
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Genode::Weak_ptr<NODE>&node() { return _node; }
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File_system::Listener &listener() { return *_listener; }
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Genode::Id_space<File_system::Node>::Id id() { return _element.id(); }
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/**
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* Register packet stream sink to be notified of node changes
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*/
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void register_notify(File_system::Sink &sink)
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{
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Genode::Locked_ptr<NODE> node { _node };
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/*
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* If there was already a handler registered for the node,
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* remove the old handler.
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*/
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if (_listener.constructed()) {
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if (node.valid())
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node->remove_listener(&*_listener);
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_listener.destruct();
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}
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/*
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* Register new handler
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*/
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if (node.valid()) {
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_listener.construct(sink, id(), _version_when_opened);
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node->add_listener(&*_listener);
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}
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}
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void mark_as_written() { _was_written = true; }
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void unmark_as_written() { _was_written = false; }
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};
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#endif /* _OPEN_NODE_H_ */
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