155 lines
3.9 KiB
C++
155 lines
3.9 KiB
C++
/*
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* \brief Inline filesystem
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* \author Norman Feske
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* \date 2014-04-14
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*
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* This file system allows the content of a file being specified as the content
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* of its config node.
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*/
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/*
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* Copyright (C) 2014-2017 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__INLINE_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__INLINE_FILE_SYSTEM_H_
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#include <vfs/file_system.h>
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namespace Vfs { class Inline_file_system; }
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class Vfs::Inline_file_system : public Single_file_system
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{
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private:
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Xml_node _node;
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class Inline_vfs_handle : public Single_vfs_handle
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{
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private:
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char const * const _base;
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file_size const _size;
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/*
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* Noncopyable
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*/
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Inline_vfs_handle(Inline_vfs_handle const &);
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Inline_vfs_handle &operator = (Inline_vfs_handle const &);
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public:
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Inline_vfs_handle(Directory_service &ds,
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File_io_service &fs,
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Genode::Allocator &alloc,
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char const * const base,
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file_size const size)
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: Single_vfs_handle(ds, fs, alloc, 0),
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_base(base), _size(size)
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{ }
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Read_result read(char *dst, file_size count,
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file_size &out_count) override
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{
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/* file read limit is the size of the dataspace */
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file_size const max_size = _size;
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/* current read offset */
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file_size const read_offset = seek();
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/* maximum read offset, clamped to dataspace size */
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file_size const end_offset = min(count + read_offset, max_size);
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/* source address within the dataspace */
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char const *src = _base + read_offset;
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/* check if end of file is reached */
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if (read_offset >= end_offset) {
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out_count = 0;
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return READ_OK;
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}
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/* copy-out bytes from ROM dataspace */
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file_size const num_bytes = end_offset - read_offset;
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memcpy(dst, src, num_bytes);
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out_count = num_bytes;
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return READ_OK;
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}
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Write_result write(char const *, file_size,
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file_size &out_count) override
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{
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out_count = 0;
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return WRITE_ERR_INVALID;
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}
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bool read_ready() override { return true; }
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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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* The 'config' XML node (that points to its content) is stored within
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* the object after construction time. The underlying backing store
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* must be kept in tact during the lifefile of the object.
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*/
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Inline_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::rx(), config),
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_node(config)
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{ }
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static char const *name() { return "inline"; }
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char const *type() override { return "inline"; }
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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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/* empty node */
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if (_node.content_size() == 0) {
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*out_handle = new (alloc)
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Inline_vfs_handle(*this, *this, alloc, nullptr, 0);
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return OPEN_OK;
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}
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try {
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_node.with_raw_content([&] (char const *base, Genode::size_t size) {
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*out_handle = new (alloc)
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Inline_vfs_handle(*this, *this, alloc, base, size);
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});
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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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Stat_result stat(char const *path, Stat &out) override
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{
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Stat_result const result = Single_file_system::stat(path, out);
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_node.with_raw_content([&] (char const *, Genode::size_t size) {
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out.size = size; });
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return result;
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}
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};
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#endif /* _INCLUDE__VFS__INLINE_FILE_SYSTEM_H_ */
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