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vfs: inline file system

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Norman Feske 2014-04-14 16:30:09 +02:00 committed by Christian Helmuth
parent 959b26fee0
commit 8e74fdc585
1 changed files with 97 additions and 0 deletions
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os/include/vfs/inline_file_system.h Normal file
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/*
* \brief Inline filesystem
* \author Norman Feske
* \date 2014-04-14
*
* This file system allows the content of a file being specified as the content
* of its config node.
*/
/*
* Copyright (C) 2014 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__VFS__INLINE_FILE_SYSTEM_H_
#define _INCLUDE__VFS__INLINE_FILE_SYSTEM_H_
#include <vfs/file_system.h>
namespace Vfs { class Inline_file_system; }
class Vfs::Inline_file_system : public Single_file_system
{
private:
char const * const _base;
size_t const _size;
public:
Inline_file_system(Xml_node config)
:
Single_file_system(NODE_TYPE_FILE, name(), config),
_base(config.content_base()),
_size(config.content_size())
{ }
static char const *name() { return "inline"; }
/********************************
** File I/O service interface **
********************************/
Stat_result stat(char const *path, Stat &out) override
{
Stat_result result = Single_file_system::stat(path, out);
out.size = _size;
return result;
}
/********************************
** File I/O service interface **
********************************/
Write_result write(Vfs_handle *, char const *, size_t, size_t &count_out) override
{
count_out = 0;
return WRITE_ERR_INVALID;
}
Read_result read(Vfs_handle *vfs_handle, char *dst, size_t count,
size_t &out_count) override
{
/* file read limit is the size of the dataspace */
size_t const max_size = _size;
/* current read offset */
size_t const read_offset = vfs_handle->seek();
/* maximum read offset, clamped to dataspace size */
size_t const end_offset = min(count + read_offset, max_size);
/* source address within the dataspace */
char const *src = _base + read_offset;
/* check if end of file is reached */
if (read_offset >= end_offset) {
out_count = 0;
return READ_OK;
}
/* copy-out bytes from ROM dataspace */
size_t const num_bytes = end_offset - read_offset;
memcpy(dst, src, num_bytes);
out_count = num_bytes;
return READ_OK;
}
};
#endif /* _INCLUDE__VFS__INLINE_FILE_SYSTEM_H_ */