90 lines
2.1 KiB
C++
90 lines
2.1 KiB
C++
/*
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* \brief null filesystem
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* \author Josef Soentgen
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* \author Norman Feske
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* \date 2012-07-31
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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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#ifndef _INCLUDE__VFS__NULL_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__NULL_FILE_SYSTEM_H_
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#include <vfs/single_file_system.h>
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namespace Vfs { class Null_file_system; }
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struct Vfs::Null_file_system : Single_file_system
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{
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Null_file_system(Vfs::Env&, Genode::Xml_node config)
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:
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Single_file_system(Node_type::CONTINUOUS_FILE, name(),
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Node_rwx::rw(), config)
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{ }
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static char const *name() { return "null"; }
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char const *type() override { return "null"; }
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struct Null_vfs_handle : Single_vfs_handle
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{
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Null_vfs_handle(Directory_service &ds,
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File_io_service &fs,
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Genode::Allocator &alloc)
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: Single_vfs_handle(ds, fs, alloc, 0) { }
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Read_result read(char *, file_size, file_size &out_count) override
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{
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out_count = 0;
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return READ_OK;
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}
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Write_result write(char const *, file_size count,
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file_size &out_count) override
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{
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out_count = count;
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return WRITE_OK;
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}
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bool read_ready() override { return false; }
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};
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/*********************************
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** Directory service interface **
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*********************************/
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Open_result open(char const *path, unsigned,
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Vfs_handle **out_handle,
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Allocator &alloc) override
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{
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if (!_single_file(path))
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return OPEN_ERR_UNACCESSIBLE;
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try {
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*out_handle = new (alloc)
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Null_vfs_handle(*this, *this, alloc);
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return OPEN_OK;
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}
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catch (Genode::Out_of_ram) { return OPEN_ERR_OUT_OF_RAM; }
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catch (Genode::Out_of_caps) { return OPEN_ERR_OUT_OF_CAPS; }
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}
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/********************************
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** File I/O service interface **
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********************************/
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Ftruncate_result ftruncate(Vfs_handle *, file_size) override
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{
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return FTRUNCATE_OK;
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}
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};
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#endif /* _INCLUDE__VFS__NULL_FILE_SYSTEM_H_ */
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