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/* Copyright (C) 2003 MySQL AB
This program 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; version 2 of the License.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation // gcc: Class implementation
#endif
#include "mysql_priv.h"
#include "transparent_file.h"
Transparent_file::Transparent_file() : lower_bound(0), buff_size(IO_SIZE)
{
buff= (uchar *) my_malloc(buff_size*sizeof(uchar), MYF(MY_WME));
}
Transparent_file::~Transparent_file()
{
my_free((uchar*)buff, MYF(MY_ALLOW_ZERO_PTR));
}
void Transparent_file::init_buff(File filedes_arg)
{
filedes= filedes_arg;
/* read the beginning of the file */
lower_bound= 0;
VOID(my_seek(filedes, 0, MY_SEEK_SET, MYF(0)));
if (filedes && buff)
upper_bound= my_read(filedes, buff, buff_size, MYF(0));
}
uchar *Transparent_file::ptr()
{
return buff;
}
off_t Transparent_file::start()
{
return lower_bound;
}
off_t Transparent_file::end()
{
return upper_bound;
}
off_t Transparent_file::read_next()
{
size_t bytes_read;
/*
No need to seek here, as the file managed by Transparent_file class
always points to upper_bound byte
*/
if ((bytes_read= my_read(filedes, buff, buff_size, MYF(0))) == MY_FILE_ERROR)
return (off_t) -1;
/* end of file */
if (!bytes_read)
return (off_t) -1;
lower_bound= upper_bound;
upper_bound+= bytes_read;
return lower_bound;
}
char Transparent_file::get_value(off_t offset)
{
size_t bytes_read;
/* check boundaries */
if ((lower_bound <= offset) && (offset < upper_bound))
return buff[offset - lower_bound];
VOID(my_seek(filedes, offset, MY_SEEK_SET, MYF(0)));
/* read appropriate portion of the file */
if ((bytes_read= my_read(filedes, buff, buff_size,
MYF(0))) == MY_FILE_ERROR)
return 0;
lower_bound= offset;
upper_bound= lower_bound + bytes_read;
/* end of file */
if (upper_bound == offset)
return 0;
return buff[0];
}
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