/*******************************************************************************

    Copyright(C) Jonas 'Sortie' Termansen 2013.

    This file is part of Sortix.

    Sortix is free software: you can redistribute it and/or modify it under the
    terms of the GNU General Public License as published by the Free Software
    Foundation, either version 3 of the License, or (at your option) any later
    version.

    Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
    details.

    You should have received a copy of the GNU General Public License along with
    Sortix. If not, see <http://www.gnu.org/licenses/>.

    fs/zero.cpp
    Bit bucket special device.

*******************************************************************************/

#include <sys/types.h>

#include <stdint.h>
#include <string.h>

#include <sortix/stat.h>

#include <sortix/kernel/inode.h>
#include <sortix/kernel/ioctx.h>

#include "zero.h"

namespace Sortix {

Zero::Zero(dev_t dev, ino_t ino, uid_t owner, gid_t group, mode_t mode)
{
	inode_type = INODE_TYPE_STREAM;
	if ( !dev )
		dev = (dev_t) this;
	if ( !ino )
		ino = (ino_t) this;
	this->type = S_IFCHR;
	this->stat_uid = owner;
	this->stat_gid = group;
	this->stat_mode = (mode & S_SETABLE) | this->type;
	this->stat_size = 0;
	this->stat_blksize = 1;
	this->dev = dev;
	this->ino = ino;
}

Zero::~Zero()
{
}

int Zero::truncate(ioctx_t* /*ctx*/, off_t /*length*/)
{
	return 0;
}

off_t Zero::lseek(ioctx_t* /*ctx*/, off_t offset, int /*whence*/)
{
	return offset;
}

ssize_t Zero::read(ioctx_t* ctx, uint8_t* buf, size_t count)
{
	const size_t ZERO_MEM_SIZE = 128;
	uint8_t zero_mem[ZERO_MEM_SIZE];
	memset(zero_mem, 0, ZERO_MEM_SIZE);
	size_t sofar = 0;
	while ( sofar < count )
	{
		size_t left = count - sofar;
		size_t amount = left < ZERO_MEM_SIZE ? left : ZERO_MEM_SIZE;
		ctx->copy_to_dest(buf + sofar, zero_mem, amount);
		sofar += amount;
	}
	return (ssize_t) sofar;
}

ssize_t Zero::pread(ioctx_t* ctx, uint8_t* buf, size_t count, off_t /*off*/)
{
	return read(ctx, buf, count);
}

ssize_t Zero::write(ioctx_t* /*ctx*/, const uint8_t* /*buf*/, size_t count)
{
	return count;
}

ssize_t Zero::pwrite(ioctx_t* /*ctx*/, const uint8_t* /*buf*/, size_t count,
                    off_t /*off*/)
{
	return count;
}

} // namespace Sortix