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144 lines
3.2 KiB
C++
144 lines
3.2 KiB
C++
/*
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* \brief ROM filesystem
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* \author Norman Feske
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* \date 2014-04-14
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*/
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/*
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* Copyright (C) 2014 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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#ifndef _INCLUDE__VFS__ROM_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__ROM_FILE_SYSTEM_H_
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#include <os/attached_rom_dataspace.h>
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#include <vfs/file_system.h>
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namespace Vfs { class Rom_file_system; }
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class Vfs::Rom_file_system : public Single_file_system
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{
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private:
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struct Label
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{
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enum { LABEL_MAX_LEN = 64 };
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char string[LABEL_MAX_LEN];
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Label(Xml_node config)
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{
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/* obtain label from config */
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string[0] = 0;
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try { config.attribute("label").value(string, sizeof(string)); }
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catch (...)
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{
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/* use VFS node name if label was not provided */
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string[0] = 0;
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try { config.attribute("name").value(string, sizeof(string)); }
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catch (...) { }
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}
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}
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} _label;
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Genode::Attached_rom_dataspace _rom;
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public:
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Rom_file_system(Xml_node config)
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:
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Single_file_system(NODE_TYPE_FILE, name(), config),
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_label(config),
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_rom(_label.string)
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{ }
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static char const *name() { return "rom"; }
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/*********************************
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** Directory-service interface **
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********************************/
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Dataspace_capability dataspace(char const *path) override
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{
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return _rom.cap();
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}
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/*
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* Overwrite the default open function to update the ROM dataspace
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* each time when opening the corresponding file.
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*/
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Open_result open(char const *path, unsigned,
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Vfs_handle **out_handle) override
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{
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Open_result const result =
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Single_file_system::open(path, 0, out_handle);
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_rom.update();
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return result;
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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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Stat_result stat(char const *path, Stat &out) override
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{
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Stat_result result = Single_file_system::stat(path, out);
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_rom.update();
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out.size = _rom.is_valid() ? _rom.size() : 0;
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return result;
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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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Write_result write(Vfs_handle *, char const *, file_size,
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file_size &count_out) override
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{
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count_out = 0;
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return WRITE_ERR_INVALID;
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}
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Read_result read(Vfs_handle *vfs_handle, 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 = _rom.size();
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/* current read offset */
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file_size const read_offset = vfs_handle->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 = _rom.local_addr<char>() + 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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};
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#endif /* _INCLUDE__VFS__ROM_FILE_SYSTEM_H_ */
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