mirror of
https://github.com/genodelabs/genode.git
synced 2024-12-27 01:11:06 +00:00
114 lines
2.5 KiB
C++
114 lines
2.5 KiB
C++
/*
|
|
* \brief File node
|
|
* \author Norman Feske
|
|
* \date 2012-04-11
|
|
*/
|
|
|
|
/*
|
|
* Copyright (C) 2012-2015 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__RAM_FS__FILE_H_
|
|
#define _INCLUDE__RAM_FS__FILE_H_
|
|
|
|
/* Genode includes */
|
|
#include <base/allocator.h>
|
|
|
|
/* local includes */
|
|
#include <ram_fs/node.h>
|
|
#include <ram_fs/chunk.h>
|
|
|
|
namespace File_system { class File; }
|
|
|
|
|
|
class File_system::File : public Node
|
|
{
|
|
private:
|
|
|
|
typedef Chunk<4096> Chunk_level_3;
|
|
typedef Chunk_index<128, Chunk_level_3> Chunk_level_2;
|
|
typedef Chunk_index<64, Chunk_level_2> Chunk_level_1;
|
|
typedef Chunk_index<64, Chunk_level_1> Chunk_level_0;
|
|
|
|
Chunk_level_0 _chunk;
|
|
|
|
file_size_t _length;
|
|
|
|
public:
|
|
|
|
File(Allocator &alloc, char const *name)
|
|
: _chunk(alloc, 0), _length(0) { Node::name(name); }
|
|
|
|
size_t read(char *dst, size_t len, seek_off_t seek_offset)
|
|
{
|
|
file_size_t const chunk_used_size = _chunk.used_size();
|
|
|
|
if (seek_offset >= _length)
|
|
return 0;
|
|
|
|
/*
|
|
* Constrain read transaction to available chunk data
|
|
*
|
|
* Note that 'chunk_used_size' may be lower than '_length'
|
|
* because 'Chunk' may have truncated tailing zeros.
|
|
*/
|
|
if (seek_offset + len >= _length)
|
|
len = _length - seek_offset;
|
|
|
|
file_size_t read_len = len;
|
|
|
|
if (seek_offset + read_len > chunk_used_size) {
|
|
if (chunk_used_size >= seek_offset)
|
|
read_len = chunk_used_size - seek_offset;
|
|
else
|
|
read_len = 0;
|
|
}
|
|
|
|
_chunk.read(dst, read_len, seek_offset);
|
|
|
|
/* add zero padding if needed */
|
|
if (read_len < len)
|
|
memset(dst + read_len, 0, len - read_len);
|
|
|
|
return len;
|
|
}
|
|
|
|
size_t write(char const *src, size_t len, seek_off_t seek_offset)
|
|
{
|
|
if (seek_offset == (seek_off_t)(~0))
|
|
seek_offset = _chunk.used_size();
|
|
|
|
if (seek_offset + len >= Chunk_level_0::SIZE)
|
|
throw Size_limit_reached();
|
|
|
|
_chunk.write(src, len, (size_t)seek_offset);
|
|
|
|
/*
|
|
* Keep track of file length. We cannot use 'chunk.used_size()'
|
|
* as file length because trailing zeros may by represented
|
|
* by zero chunks, which do not contribute to 'used_size()'.
|
|
*/
|
|
_length = max(_length, seek_offset + len);
|
|
|
|
mark_as_updated();
|
|
return len;
|
|
}
|
|
|
|
file_size_t length() const { return _length; }
|
|
|
|
void truncate(file_size_t size)
|
|
{
|
|
if (size < _chunk.used_size())
|
|
_chunk.truncate(size);
|
|
|
|
_length = size;
|
|
|
|
mark_as_updated();
|
|
}
|
|
};
|
|
|
|
#endif /* _INCLUDE__RAM_FS__FILE_H_ */
|