570 lines
14 KiB
C++
570 lines
14 KiB
C++
/*
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* \brief FUSE file system
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* \author Josef Soentgen
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* \date 2013-11-27
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*/
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/*
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* Copyright (C) 2013 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 General Public License version 2.
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*/
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/* Genode includes */
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#include <file_system/node_handle_registry.h>
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#include <file_system_session/rpc_object.h>
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#include <os/attached_rom_dataspace.h>
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#include <os/config.h>
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#include <os/server.h>
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#include <os/session_policy.h>
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#include <root/component.h>
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#include <util/xml_node.h>
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/* libc includes */
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#include <errno.h>
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/* local includes */
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#include <directory.h>
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#include <util.h>
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static bool const verbose = false;
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#define PDBGV(...) if (verbose) PDBG(__VA_ARGS__)
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namespace File_system {
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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 File_system::Session_component : public Session_rpc_object
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{
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private:
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Server::Entrypoint &_ep;
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Allocator &_md_alloc;
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Directory &_root;
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Node_handle_registry _handle_registry;
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bool _writeable;
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Signal_rpc_member<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, Node &node)
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{
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void * const content = tx_sink()->packet_content(packet);
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size_t const length = packet.length();
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seek_off_t const offset = packet.position();
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if (!content || (packet.length() > packet.size())) {
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packet.succeeded(false);
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return;
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}
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/* resulting length */
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size_t res_length = 0;
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switch (packet.operation()) {
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case Packet_descriptor::READ:
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res_length = node.read((char *)content, length, offset);
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break;
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case Packet_descriptor::WRITE:
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/* session is read-only */
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if (!_writeable)
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break;
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res_length = node.write((char const *)content, length, offset);
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break;
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}
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packet.length(res_length);
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packet.succeeded(res_length > 0);
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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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try {
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Node *node = _handle_registry.lookup_and_lock(packet.handle());
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Node_lock_guard guard(node);
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_process_packet_op(packet, *node);
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}
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catch (Invalid_handle) { PERR("Invalid_handle"); }
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catch (Size_limit_reached) { PERR("Size_limit_reached"); }
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/*
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* The 'acknowledge_packet' function cannot block because we
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* checked for 'ready_to_ack' in '_process_packets'.
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*/
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tx_sink()->acknowledge_packet(packet);
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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(unsigned)
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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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PWRN("malformed path '%s'", 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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Server::Entrypoint &ep,
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char const *root_dir,
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bool writeable,
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Allocator &md_alloc)
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:
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Session_rpc_object(env()->ram_session()->alloc(tx_buf_size), ep.rpc_ep()),
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_ep(ep),
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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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_writeable(writeable),
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_process_packet_dispatcher(_ep, *this, &Session_component::_process_packets)
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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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Fuse::sync_fs();
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Dataspace_capability ds = tx_sink()->dataspace();
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env()->ram_session()->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_filename(name.string()))
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throw Invalid_name();
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Directory *dir = _handle_registry.lookup_and_lock(dir_handle);
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Node_lock_guard dir_guard(dir);
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PDBGV("dir: '%s' name: '%s' %s", dir->name(), name.string(),
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create ? "create" : "");
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if (create && !_writeable)
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throw Permission_denied();
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File *file = new (&_md_alloc) File(dir, name.string(), mode, create);
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Node_lock_guard file_guard(file);
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return _handle_registry.alloc(file);
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}
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Symlink_handle symlink(Dir_handle dir_handle, Name const &name, bool create)
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{
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if (! Fuse::support_symlinks()) {
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PERR("FUSE file system does not support symlinks");
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return Symlink_handle();
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}
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if (!valid_filename(name.string()))
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throw Invalid_name();
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Directory *dir = _handle_registry.lookup_and_lock(dir_handle);
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Node_lock_guard dir_guard(dir);
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PDBGV("dir: '%s' name: '%s'", dir->name(), name.string());
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if (create && !_writeable)
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throw Permission_denied();
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Symlink *symlink = new (&_md_alloc) Symlink(dir, name.string(), create);
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Node_lock_guard symlink_guard(symlink);
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return _handle_registry.alloc(symlink);
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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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PDBGV("path: '%s'", path_str);
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if (create && !_writeable)
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throw Permission_denied();
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if (!path.is_valid_string())
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throw Name_too_long();
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Directory *dir_node = new (&_md_alloc) Directory(_md_alloc, path_str, create);
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Node_lock_guard guard(dir_node);
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return _handle_registry.alloc(dir_node);
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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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/**
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* FIXME this leads to '/' as parent and 'the rest' as name,
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* which fortunatly is in this case not a problem.
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*/
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PDBGV("path_str: '%s'", path_str);
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Node *node = _root.node(path_str + 1);
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Node_lock_guard guard(node);
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return _handle_registry.alloc(node);
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}
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void close(Node_handle handle)
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{
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Node *node;
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try {
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node = _handle_registry.lookup_and_lock(handle);
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/**
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* We need to call unlock() here because the handle registry
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* calls lock() itself on the node.
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*/
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node->unlock();
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} catch (Invalid_handle) {
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PERR("close() called with invalid handle");
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return;
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}
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PDBGV("node: %p name: '%s'", node, node->name());
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_handle_registry.free(handle);
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destroy(&_md_alloc, node);
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}
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Status status(Node_handle node_handle)
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{
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Node *node = _handle_registry.lookup_and_lock(node_handle);
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Node_lock_guard guard(node);
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File *file = dynamic_cast<File *>(node);
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if (file)
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return file->status();
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Directory *dir = dynamic_cast<Directory *>(node);
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if (dir)
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return dir->status();
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Symlink *symlink = dynamic_cast<Symlink *>(node);
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if (symlink)
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return symlink->status();
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return Status();
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}
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void control(Node_handle, Control)
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{
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PERR("%s not implemented", __func__);
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}
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void unlink(Dir_handle dir_handle, Name const &name)
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{
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if (!_writeable)
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throw Permission_denied();
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Directory *dir = _handle_registry.lookup_and_lock(dir_handle);
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Node_lock_guard dir_guard(dir);
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PDBGV("dir: '%s' name: '%s'", dir->name(), name.string());
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Absolute_path absolute_path(_root.name());
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try {
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absolute_path.append(dir->name());
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absolute_path.append("/");
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absolute_path.append(name.string());
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} catch (Path_base::Path_too_long) {
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throw Invalid_name();
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}
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/* XXX remove direct use of FUSE operations */
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int res = Fuse::fuse()->op.unlink(absolute_path.base());
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if (res != 0) {
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PERR("fuse()->op.unlink() returned unexpected error code: %d", res);
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return;
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}
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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 (!_writeable)
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throw Permission_denied();
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File *file;
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try { file = _handle_registry.lookup_and_lock(file_handle); }
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catch (Invalid_handle) { throw Lookup_failed(); }
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Node_lock_guard file_guard(file);
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file->truncate(size);
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}
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void move(Dir_handle from_dir_handle, Name const &from_name,
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Dir_handle to_dir_handle, Name const &to_name)
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{
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if (!_writeable)
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throw Permission_denied();
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Directory *from_dir, *to_dir;
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try { from_dir = _handle_registry.lookup_and_lock(from_dir_handle); }
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catch (Invalid_handle) { throw Lookup_failed(); }
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try { to_dir = _handle_registry.lookup_and_lock(to_dir_handle); }
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catch (Invalid_handle) {
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from_dir->unlock();
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throw Lookup_failed();
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}
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Node_lock_guard from_dir_guard(from_dir);
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Node_lock_guard to_dir_guard(to_dir);
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PDBGV("from_dir: '%s' from_name: '%s', to_dir: '%s' to_name: '%s'",
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from_dir->name(), from_name.string(), to_dir->name(), to_name.string());
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Absolute_path absolute_from_path(_root.name());
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Absolute_path absolute_to_path(_root.name());
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try {
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absolute_from_path.append(from_dir->name());
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absolute_from_path.append("/");
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absolute_from_path.append(from_name.string());
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absolute_to_path.append(to_dir->name());
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absolute_to_path.append("/");
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absolute_to_path.append(to_name.string());
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} catch (Path_base::Path_too_long) {
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throw Invalid_name();
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}
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PDBGV("from_path = %s", absolute_from_path.base());
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PDBGV("to_path = %s", absolute_to_path.base());
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/* XXX remove direct use of FUSE operations */
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int res = Fuse::fuse()->op.rename(absolute_to_path.base(),
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absolute_from_path.base());
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if (res != 0) {
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PERR("fuse()->op.rename() returned unexpected error code: %d", res);
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return;
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}
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}
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void sigh(Node_handle node_handle, Signal_context_capability sigh)
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{
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_handle_registry.sigh(node_handle, sigh);
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}
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void sync()
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{
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Fuse::sync_fs();
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}
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};
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class File_system::Root : public Root_component<Session_component>
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{
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private:
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Server::Entrypoint &_ep;
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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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try {
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Session_label label(args);
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Session_policy policy(label);
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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 skip the first character.
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*/
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if (root[0] != '/')
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throw Lookup_failed();
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root_dir = root;
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} catch (Xml_node::Nonexistent_attribute) {
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PERR("Missing \"root\" attribute in policy definition");
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throw Root::Unavailable();
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} catch (Lookup_failed) {
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PERR("Session root directory \"%s\" does not exist", root);
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throw Root::Unavailable();
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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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try {
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writeable = policy.attribute("writeable").has_value("yes");
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PWRN("WARNING: write support in fuse_fs is considered experimental, data-loss may occur.");
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} catch (Xml_node::Nonexistent_attribute) { }
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} catch (Session_policy::No_policy_defined) {
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PERR("Invalid session request, no matching policy");
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throw Root::Unavailable();
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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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/*
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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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PERR("insufficient 'ram_quota', got %zd, need %zd",
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ram_quota, session_size);
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throw Root::Quota_exceeded();
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}
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return new (md_alloc())
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Session_component(tx_buf_size, _ep, root_dir, writeable, *md_alloc());
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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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* \param ep entrypoint
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* \param sig_rec signal receiver used for handling the
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* data-flow signals of packet streams
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* \param md_alloc meta-data allocator
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*/
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Root(Server::Entrypoint &ep, Allocator &md_alloc)
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:
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Root_component<Session_component>(&ep.rpc_ep(), &md_alloc),
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_ep(ep)
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{ }
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};
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struct File_system::Main
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{
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Server::Entrypoint &ep;
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/*
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* Initialize root interface
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*/
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Sliced_heap sliced_heap = { env()->ram_session(), env()->rm_session() };
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Root fs_root = { ep, sliced_heap };
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Main(Server::Entrypoint &ep) : ep(ep)
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{
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if (!Fuse::init_fs()) {
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PERR("FUSE fs initialization failed");
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return;
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}
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env()->parent()->announce(ep.manage(fs_root));
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}
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~Main()
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{
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if (Fuse::initialized()) {
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Fuse::deinit_fs();
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}
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}
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};
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/**********************
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** Server framework **
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**********************/
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char const * Server::name() { return "fuse_fs_ep"; }
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/**
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* The large stack is needed because FUSE file system may call
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* libc functions that require a large stack, e.g. timezone
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* related functions.
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*/
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Genode::size_t Server::stack_size() { return 8192 * sizeof(long); }
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void Server::construct(Server::Entrypoint &ep) { static File_system::Main inst(ep); }
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