475 lines
12 KiB
C++
475 lines
12 KiB
C++
/*
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* \brief Internal nodes of VFS server
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* \author Emery Hemingway
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* \author Christian Helmuth
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* \date 2016-03-29
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*/
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/*
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* Copyright (C) 2016-2017 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 _VFS__NODE_H_
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#define _VFS__NODE_H_
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/* Genode includes */
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#include <file_system/node.h>
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#include <vfs/file_system.h>
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#include <os/path.h>
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#include <base/id_space.h>
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/* Local includes */
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#include "assert.h"
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namespace Vfs_server {
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using namespace File_system;
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using namespace Vfs;
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struct Node;
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struct Directory;
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struct File;
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struct Symlink;
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typedef Genode::Id_space<Node> Node_space;
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struct Node_io_handler
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{
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virtual void handle_node_io(Node &node) = 0;
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};
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/**
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* Read/write operation incomplete exception
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*
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* The operation can be retried later.
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*/
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struct Operation_incomplete { };
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/* Vfs::MAX_PATH is shorter than File_system::MAX_PATH */
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enum { MAX_PATH_LEN = Vfs::MAX_PATH_LEN };
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typedef Genode::Path<MAX_PATH_LEN> Path;
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typedef Genode::Allocator::Out_of_memory Out_of_memory;
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/**
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* Type trait for determining the node type for a given handle type
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*/
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template<typename T> struct Node_type;
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template<> struct Node_type<Node_handle> { typedef Node Type; };
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template<> struct Node_type<Dir_handle> { typedef Directory Type; };
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template<> struct Node_type<File_handle> { typedef File Type; };
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template<> struct Node_type<Symlink_handle> { typedef Symlink Type; };
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/**
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* Type trait for determining the handle type for a given node type
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*/
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template<typename T> struct Handle_type;
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template<> struct Handle_type<Node> { typedef Node_handle Type; };
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template<> struct Handle_type<Directory> { typedef Dir_handle Type; };
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template<> struct Handle_type<File> { typedef File_handle Type; };
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template<> struct Handle_type<Symlink> { typedef Symlink_handle Type; };
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/*
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* Note that the file objects are created at the
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* VFS in the local node constructors, this is to
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* ensure that Out_of_ram is thrown before
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* the VFS is modified.
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*/
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}
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class Vfs_server::Node : public File_system::Node_base, public Node_space::Element,
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public Vfs::Vfs_handle::Context
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{
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public:
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enum Op_state { IDLE, READ_QUEUED, SYNC_QUEUED };
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private:
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Path const _path;
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Mode const _mode;
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bool _notify_read_ready = false;
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protected:
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Node_io_handler &_node_io_handler;
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Vfs::Vfs_handle *_handle { nullptr };
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Op_state op_state { Op_state::IDLE };
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size_t _read(char *dst, size_t len, seek_off_t seek_offset)
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{
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_handle->seek(seek_offset);
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typedef Vfs::File_io_service::Read_result Result;
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Vfs::file_size out_count = 0;
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Result out_result = Result::READ_OK;
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switch (op_state) {
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case Op_state::IDLE:
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if (!_handle->fs().queue_read(_handle, len))
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throw Operation_incomplete();
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/* fall through */
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case Op_state::READ_QUEUED:
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out_result = _handle->fs().complete_read(_handle, dst, len,
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out_count);
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switch (out_result) {
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case Result::READ_OK:
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op_state = Op_state::IDLE;
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return out_count;
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case Result::READ_ERR_WOULD_BLOCK:
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case Result::READ_ERR_AGAIN:
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case Result::READ_ERR_INTERRUPT:
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op_state = Op_state::IDLE;
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throw Operation_incomplete();
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case Result::READ_ERR_IO:
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case Result::READ_ERR_INVALID:
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op_state = Op_state::IDLE;
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/* FIXME revise error handling */
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return 0;
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case Result::READ_QUEUED:
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op_state = Op_state::READ_QUEUED;
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throw Operation_incomplete();
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}
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break;
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case Op_state::SYNC_QUEUED:
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throw Operation_incomplete();
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}
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return 0;
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}
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size_t _write(char const *src, size_t len,
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seek_off_t seek_offset)
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{
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Vfs::file_size res = 0;
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_handle->seek(seek_offset);
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try {
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_handle->fs().write(_handle, src, len, res);
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} catch (Vfs::File_io_service::Insufficient_buffer) {
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throw Operation_incomplete();
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}
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if (res)
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mark_as_updated();
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return res;
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}
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public:
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Node(Node_space &space, char const *node_path, Mode node_mode,
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Node_io_handler &node_io_handler)
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:
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Node_space::Element(*this, space),
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_path(node_path), _mode(node_mode),
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_node_io_handler(node_io_handler)
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{ }
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virtual ~Node() { }
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char const *path() { return _path.base(); }
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Mode mode() const { return _mode; }
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virtual size_t read(char *dst, size_t len, seek_off_t seek_offset)
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{ return 0; }
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virtual size_t write(char const *src, size_t len,
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seek_off_t seek_offset) { return 0; }
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bool read_ready() { return _handle->fs().read_ready(_handle); }
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void handle_io_response()
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{
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_node_io_handler.handle_node_io(*this);
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}
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void notify_read_ready(bool requested)
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{
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if (requested)
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_handle->fs().notify_read_ready(_handle);
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_notify_read_ready = requested;
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}
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bool notify_read_ready() const { return _notify_read_ready; }
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void sync()
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{
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typedef Vfs::File_io_service::Sync_result Result;
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Result out_result = Result::SYNC_OK;
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switch (op_state) {
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case Op_state::IDLE:
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if (!_handle->fs().queue_sync(_handle))
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throw Operation_incomplete();
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/* fall through */
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case Op_state::SYNC_QUEUED:
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out_result = _handle->fs().complete_sync(_handle);
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switch (out_result) {
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case Result::SYNC_OK:
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op_state = Op_state::IDLE;
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return;
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case Result::SYNC_QUEUED:
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op_state = Op_state::SYNC_QUEUED;
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throw Operation_incomplete();
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}
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break;
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case Op_state::READ_QUEUED:
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throw Operation_incomplete();
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}
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}
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};
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struct Vfs_server::Symlink : Node
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{
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Symlink(Node_space &space,
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Vfs::File_system &vfs,
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Genode::Allocator &alloc,
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Node_io_handler &node_io_handler,
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char const *link_path,
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Mode mode,
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bool create)
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: Node(space, link_path, mode, node_io_handler)
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{
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assert_openlink(vfs.openlink(link_path, create, &_handle, alloc));
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_handle->context = this;
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}
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/********************
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** Node interface **
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********************/
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size_t read(char *dst, size_t len, seek_off_t seek_offset)
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{
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if (seek_offset != 0) {
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/* partial read is not supported */
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return 0;
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}
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return _read(dst, len, 0);
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}
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size_t write(char const *src, size_t len, seek_off_t seek_offset)
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{
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/*
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* if the symlink target is too long return a short result
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* because a competent File_system client will error on a
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* length mismatch
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*/
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if (len > MAX_PATH_LEN) {
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return len >> 1;
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}
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/* ensure symlink gets something null-terminated */
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Genode::String<MAX_PATH_LEN+1> target(Genode::Cstring(src, len));
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size_t const target_len = target.length()-1;
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file_size out_count;
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if (_handle->fs().write(_handle, target.string(), target_len, out_count) !=
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File_io_service::WRITE_OK)
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return 0;
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mark_as_updated();
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notify_listeners();
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return out_count;
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}
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};
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class Vfs_server::File : public Node
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{
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private:
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char const *_leaf_path; /* offset pointer to Node::_path */
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public:
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File(Node_space &space,
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Vfs::File_system &vfs,
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Genode::Allocator &alloc,
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Node_io_handler &node_io_handler,
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char const *file_path,
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Mode fs_mode,
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bool create)
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:
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Node(space, file_path, fs_mode, node_io_handler)
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{
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unsigned vfs_mode =
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(fs_mode-1) | (create ? Vfs::Directory_service::OPEN_MODE_CREATE : 0);
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assert_open(vfs.open(file_path, vfs_mode, &_handle, alloc));
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_leaf_path = vfs.leaf_path(path());
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_handle->context = this;
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}
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~File() { _handle->ds().close(_handle); }
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size_t read(char *dst, size_t len, seek_off_t seek_offset) override
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{
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if (seek_offset == SEEK_TAIL) {
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typedef Directory_service::Stat_result Result;
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Vfs::Directory_service::Stat st;
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/* if stat fails, try and see if the VFS will seek to the end */
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seek_offset = (_handle->ds().stat(_leaf_path, st) == Result::STAT_OK) ?
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((len < st.size) ? (st.size - len) : 0) : SEEK_TAIL;
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}
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return _read(dst, len, seek_offset);
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}
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size_t write(char const *src, size_t len,
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seek_off_t seek_offset) override
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{
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if (seek_offset == SEEK_TAIL) {
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typedef Directory_service::Stat_result Result;
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Vfs::Directory_service::Stat st;
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/* if stat fails, try and see if the VFS will seek to the end */
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seek_offset = (_handle->ds().stat(_leaf_path, st) == Result::STAT_OK) ?
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st.size : SEEK_TAIL;
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}
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return _write(src, len, seek_offset);
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}
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void truncate(file_size_t size)
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{
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assert_truncate(_handle->fs().ftruncate(_handle, size));
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mark_as_updated();
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}
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};
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struct Vfs_server::Directory : Node
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{
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Directory(Node_space &space,
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Vfs::File_system &vfs,
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Genode::Allocator &alloc,
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Node_io_handler &node_io_handler,
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char const *dir_path,
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bool create)
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: Node(space, dir_path, READ_ONLY, node_io_handler)
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{
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assert_opendir(vfs.opendir(dir_path, create, &_handle, alloc));
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_handle->context = this;
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}
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~Directory() { _handle->ds().close(_handle); }
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Node_space::Id file(Node_space &space,
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Vfs::File_system &vfs,
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Genode::Allocator &alloc,
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Node_io_handler &node_io_handler,
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char const *file_path,
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Mode mode,
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bool create)
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{
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Path subpath(file_path, path());
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char const *path_str = subpath.base();
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File *file;
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try {
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file = new (alloc)
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File(space, vfs, alloc, node_io_handler, path_str, mode, create);
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} catch (Out_of_memory) { throw Out_of_ram(); }
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if (create)
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mark_as_updated();
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return file->id();
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}
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Node_space::Id symlink(Node_space &space,
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Vfs::File_system &vfs,
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Genode::Allocator &alloc,
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char const *link_path,
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Mode mode,
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bool create)
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{
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Path subpath(link_path, path());
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char const *path_str = subpath.base();
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Symlink *link;
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try { link = new (alloc) Symlink(space, vfs, alloc, _node_io_handler,
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path_str, mode, create); }
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catch (Out_of_memory) { throw Out_of_ram(); }
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if (create)
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mark_as_updated();
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return link->id();
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}
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/********************
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** Node interface **
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********************/
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size_t read(char *dst, size_t len, seek_off_t seek_offset) override
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{
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Directory_service::Dirent vfs_dirent;
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size_t blocksize = sizeof(File_system::Directory_entry);
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unsigned index = (seek_offset / blocksize);
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size_t remains = len;
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while (remains >= blocksize) {
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if ((_read((char*)&vfs_dirent, sizeof(vfs_dirent),
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index * sizeof(vfs_dirent)) < sizeof(vfs_dirent)) ||
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(vfs_dirent.type == Vfs::Directory_service::DIRENT_TYPE_END))
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return len - remains;
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File_system::Directory_entry *fs_dirent = (Directory_entry *)dst;
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fs_dirent->inode = vfs_dirent.fileno;
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switch (vfs_dirent.type) {
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case Vfs::Directory_service::DIRENT_TYPE_DIRECTORY:
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fs_dirent->type = File_system::Directory_entry::TYPE_DIRECTORY;
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break;
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case Vfs::Directory_service::DIRENT_TYPE_SYMLINK:
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fs_dirent->type = File_system::Directory_entry::TYPE_SYMLINK;
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break;
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case Vfs::Directory_service::DIRENT_TYPE_FILE:
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default:
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fs_dirent->type = File_system::Directory_entry::TYPE_FILE;
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break;
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}
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strncpy(fs_dirent->name, vfs_dirent.name, MAX_NAME_LEN);
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remains -= blocksize;
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dst += blocksize;
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}
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return len - remains;
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}
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size_t write(char const *src, size_t len,
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seek_off_t seek_offset) override
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{
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return 0;
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}
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};
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#endif /* _VFS__NODE_H_ */
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