485 lines
12 KiB
C++
485 lines
12 KiB
C++
/*
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* \brief RAM file system
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* \author Norman Feske
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* \date 2012-04-11
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*/
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/*
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* Copyright (C) 2012-2017 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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/* Genode includes */
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#include <base/component.h>
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#include <base/heap.h>
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#include <base/attached_rom_dataspace.h>
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#include <root/component.h>
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#include <file_system_session/rpc_object.h>
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#include <os/session_policy.h>
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#include <util/xml_node.h>
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/* local includes */
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#include <directory.h>
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#include <open_node.h>
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namespace Lx_fs {
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using namespace File_system;
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using File_system::Packet_descriptor;
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using File_system::Path;
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struct Main;
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struct Session_component;
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struct Root;
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}
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class Lx_fs::Session_component : public Session_rpc_object
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{
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private:
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typedef File_system::Open_node<Node> Open_node;
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Genode::Env &_env;
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Allocator &_md_alloc;
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Directory &_root;
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Id_space<File_system::Node> _open_node_registry { };
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bool _writable;
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Signal_handler<Session_component> _process_packet_dispatcher;
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/******************************
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** Packet-stream processing **
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******************************/
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/**
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* Perform packet operation
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*
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* \return true on success, false on failure
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*/
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void _process_packet_op(Packet_descriptor &packet, Open_node &open_node)
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{
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size_t const length = packet.length();
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/* resulting length */
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size_t res_length = 0;
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bool succeeded = false;
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switch (packet.operation()) {
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case Packet_descriptor::READ:
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if (tx_sink()->packet_valid(packet) && (packet.length() <= packet.size())) {
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res_length = open_node.node().read((char *)tx_sink()->packet_content(packet), length,
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packet.position());
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/* read data or EOF is a success */
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succeeded = res_length || (packet.position() >= open_node.node().status().size);
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}
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break;
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case Packet_descriptor::WRITE:
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if (tx_sink()->packet_valid(packet) && (packet.length() <= packet.size())) {
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res_length = open_node.node().write((char const *)tx_sink()->packet_content(packet),
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length,
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packet.position());
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/* File system session can't handle partial writes */
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if (res_length != length) {
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Genode::error("partial write detected ",
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res_length, " vs ", length);
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/* don't acknowledge */
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return;
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}
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succeeded = true;
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}
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break;
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case Packet_descriptor::CONTENT_CHANGED:
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open_node.register_notify(*tx_sink());
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/* notify_listeners may bounce the packet back*/
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open_node.node().notify_listeners();
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/* otherwise defer acknowledgement of this packet */
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return;
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case Packet_descriptor::READ_READY:
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succeeded = true;
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/* not supported */
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break;
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case Packet_descriptor::SYNC:
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/**
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* We could call sync(2) here but for now we forward just the
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* reminder because besides testing, there is currently no
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* use-case.
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*/
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Genode::warning("SYNC not implemented!");
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succeeded = true;
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break;
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}
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packet.length(res_length);
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packet.succeeded(succeeded);
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tx_sink()->acknowledge_packet(packet);
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}
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void _process_packet()
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{
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Packet_descriptor packet = tx_sink()->get_packet();
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/* assume failure by default */
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packet.succeeded(false);
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auto process_packet_fn = [&] (Open_node &open_node) {
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_process_packet_op(packet, open_node);
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};
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try {
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_open_node_registry.apply<Open_node>(packet.handle(), process_packet_fn);
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} catch (Id_space<File_system::Node>::Unknown_id const &) {
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Genode::error("Invalid_handle");
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tx_sink()->acknowledge_packet(packet);
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}
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}
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/**
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* Called by signal dispatcher, executed in the context of the main
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* thread (not serialized with the RPC functions)
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*/
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void _process_packets()
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{
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while (tx_sink()->packet_avail()) {
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/*
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* Make sure that the '_process_packet' function does not
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* block.
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*
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* If the acknowledgement queue is full, we defer packet
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* processing until the client processed pending
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* acknowledgements and thereby emitted a ready-to-ack
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* signal. Otherwise, the call of 'acknowledge_packet()'
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* in '_process_packet' would infinitely block the context
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* of the main thread. The main thread is however needed
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* for receiving any subsequent 'ready-to-ack' signals.
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*/
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if (!tx_sink()->ready_to_ack())
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return;
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_process_packet();
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}
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}
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/**
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* Check if string represents a valid path (must start with '/')
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*/
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static void _assert_valid_path(char const *path)
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{
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if (!path || path[0] != '/') {
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Genode::warning("malformed path '", path, "'");
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throw Lookup_failed();
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}
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}
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public:
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/**
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* Constructor
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*/
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Session_component(size_t tx_buf_size,
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Genode::Env &env,
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char const *root_dir,
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bool writable,
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Allocator &md_alloc)
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:
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Session_rpc_object(env.ram().alloc(tx_buf_size), env.rm(), env.ep().rpc_ep()),
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_env(env),
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_md_alloc(md_alloc),
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_root(*new (&_md_alloc) Directory(_md_alloc, root_dir, false)),
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_writable(writable),
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_process_packet_dispatcher(env.ep(), *this, &Session_component::_process_packets)
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{
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/*
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* Register '_process_packets' dispatch function as signal
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* handler for packet-avail and ready-to-ack signals.
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*/
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_tx.sigh_packet_avail(_process_packet_dispatcher);
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_tx.sigh_ready_to_ack(_process_packet_dispatcher);
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}
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/**
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* Destructor
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*/
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~Session_component()
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{
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Dataspace_capability ds = tx_sink()->dataspace();
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_env.ram().free(static_cap_cast<Ram_dataspace>(ds));
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destroy(&_md_alloc, &_root);
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}
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/***************************
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** File_system interface **
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***************************/
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File_handle file(Dir_handle dir_handle, Name const &name, Mode mode, bool create)
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{
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if (!valid_name(name.string()))
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throw Invalid_name();
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auto file_fn = [&] (Open_node &open_node) {
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Node &dir = open_node.node();
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if (!_writable)
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if (create || (mode != STAT_ONLY && mode != READ_ONLY))
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throw Permission_denied();
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File *file = dir.file(name.string(), mode, create);
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Open_node *open_file =
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new (_md_alloc) Open_node(*file, _open_node_registry);
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return open_file->id();
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};
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try {
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return File_handle {
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_open_node_registry.apply<Open_node>(dir_handle, file_fn).value
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};
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} catch (Id_space<File_system::Node>::Unknown_id const &) {
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throw Invalid_handle();
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}
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}
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Symlink_handle symlink(Dir_handle, Name const &, bool /* create */)
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{
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Genode::error(__func__, " not implemented");
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throw Permission_denied();
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}
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Dir_handle dir(Path const &path, bool create)
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{
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char const *path_str = path.string();
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_assert_valid_path(path_str);
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/* skip leading '/' */
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path_str++;
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if (!_writable && create)
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throw Permission_denied();
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if (!path.valid_string())
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throw Name_too_long();
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Directory *dir = _root.subdir(path_str, create);
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Open_node *open_dir =
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new (_md_alloc) Open_node(*dir, _open_node_registry);
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return Dir_handle { open_dir->id().value };
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}
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Node_handle node(Path const &path)
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{
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char const *path_str = path.string();
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_assert_valid_path(path_str);
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Node *node = _root.node(path_str + 1);
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Open_node *open_node =
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new (_md_alloc) Open_node(*node, _open_node_registry);
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return open_node->id();
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}
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void close(Node_handle handle)
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{
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auto close_fn = [&] (Open_node &open_node) {
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Node &node = open_node.node();
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destroy(_md_alloc, &open_node);
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destroy(_md_alloc, &node);
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};
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try {
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_open_node_registry.apply<Open_node>(handle, close_fn);
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} catch (Id_space<File_system::Node>::Unknown_id const &) {
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throw Invalid_handle();
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}
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}
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Status status(Node_handle node_handle)
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{
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auto status_fn = [&] (Open_node &open_node) {
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return open_node.node().status();
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};
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try {
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return _open_node_registry.apply<Open_node>(node_handle, status_fn);
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} catch (Id_space<File_system::Node>::Unknown_id const &) {
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throw Invalid_handle();
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}
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}
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void control(Node_handle, Control)
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{
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Genode::error(__func__, " not implemented");
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}
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void unlink(Dir_handle, Name const &)
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{
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Genode::error(__func__, " not implemented");
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}
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void truncate(File_handle file_handle, file_size_t size)
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{
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if (!_writable)
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throw Permission_denied();
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auto truncate_fn = [&] (Open_node &open_node) {
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open_node.node().truncate(size);
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};
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try {
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_open_node_registry.apply<Open_node>(file_handle, truncate_fn);
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} catch (Id_space<File_system::Node>::Unknown_id const &) {
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throw Invalid_handle();
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}
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}
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void move(Dir_handle, Name const &, Dir_handle, Name const &)
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{
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Genode::error(__func__, " not implemented");
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}
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};
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class Lx_fs::Root : public Root_component<Session_component>
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{
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private:
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Genode::Env &_env;
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Genode::Attached_rom_dataspace _config { _env, "config" };
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protected:
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Session_component *_create_session(const char *args)
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{
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/*
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* Determine client-specific policy defined implicitly by
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* the client's label.
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*/
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char const *root_dir = ".";
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bool writeable = false;
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enum { ROOT_MAX_LEN = 256 };
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char root[ROOT_MAX_LEN];
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root[0] = 0;
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Session_label const label = label_from_args(args);
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try {
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Session_policy policy(label, _config.xml());
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/*
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* Determine directory that is used as root directory of
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* the session.
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*/
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try {
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policy.attribute("root").value(root, sizeof(root));
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/*
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* Make sure the root path is specified with a
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* leading path delimiter. For performing the
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* lookup, we remove all leading slashes.
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*/
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if (root[0] != '/') {
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Genode::error("Root directory must start with / but is \"",
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Genode::Cstring(root), "\"");
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throw Service_denied();
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}
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for (root_dir = root; *root_dir == '/'; ++root_dir) ;
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/* sanitize possibly empty root_dir to current directory */
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if (*root_dir == 0)
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root_dir = ".";
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} catch (Xml_node::Nonexistent_attribute) {
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Genode::error("missing \"root\" attribute in policy definition");
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throw Service_denied();
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}
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/*
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* Determine if write access is permitted for the session.
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*/
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writeable = policy.attribute_value("writeable", false);
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}
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catch (Session_policy::No_policy_defined) {
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Genode::error("invalid session request, no matching policy");
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throw Genode::Service_denied();
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}
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size_t ram_quota =
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Arg_string::find_arg(args, "ram_quota" ).ulong_value(0);
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size_t tx_buf_size =
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Arg_string::find_arg(args, "tx_buf_size").ulong_value(0);
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if (!tx_buf_size) {
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Genode::error(label, " requested a session with a zero length transmission buffer");
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throw Genode::Service_denied();
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}
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/*
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* Check if donated ram quota suffices for session data,
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* and communication buffer.
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*/
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size_t session_size = sizeof(Session_component) + tx_buf_size;
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if (max((size_t)4096, session_size) > ram_quota) {
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Genode::error("insufficient 'ram_quota', "
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"got ", ram_quota, ", need ", session_size);
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throw Insufficient_ram_quota();
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}
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try {
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return new (md_alloc())
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Session_component(tx_buf_size, _env, root_dir, writeable, *md_alloc());
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}
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catch (Lookup_failed) {
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Genode::error("session root directory \"", Genode::Cstring(root), "\" "
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"does not exist");
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throw Service_denied();
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}
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}
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public:
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Root(Genode::Env &env, Allocator &md_alloc)
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:
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Root_component<Session_component>(&env.ep().rpc_ep(), &md_alloc),
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_env(env)
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{ }
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};
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struct Lx_fs::Main
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{
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Genode::Env &env;
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Genode::Sliced_heap sliced_heap { env.ram(), env.rm() };
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Root fs_root = { env, sliced_heap };
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Main(Genode::Env &env) : env(env)
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{
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env.parent().announce(env.ep().manage(fs_root));
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}
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};
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void Component::construct(Genode::Env &env) { static Lx_fs::Main inst(env); }
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