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105 lines
2.6 KiB
C++
105 lines
2.6 KiB
C++
/*
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Copyright (c) 2007 MySQL AB, 2009 Sun Microsystems, Inc.
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Use is subject to license terms.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifdef USE_PRAGMA_IMPLEMENTATION
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#pragma implementation // gcc: Class implementation
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#endif
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#include "mysql_priv.h"
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#include "transparent_file.h"
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Transparent_file::Transparent_file() : lower_bound(0), buff_size(IO_SIZE)
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{
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buff= (uchar *) my_malloc(buff_size*sizeof(uchar), MYF(MY_WME));
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}
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Transparent_file::~Transparent_file()
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{
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my_free((uchar*)buff, MYF(MY_ALLOW_ZERO_PTR));
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}
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void Transparent_file::init_buff(File filedes_arg)
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{
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filedes= filedes_arg;
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/* read the beginning of the file */
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lower_bound= 0;
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VOID(my_seek(filedes, 0, MY_SEEK_SET, MYF(0)));
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if (filedes && buff)
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upper_bound= my_read(filedes, buff, buff_size, MYF(0));
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}
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uchar *Transparent_file::ptr()
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{
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return buff;
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}
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my_off_t Transparent_file::start()
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{
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return lower_bound;
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}
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my_off_t Transparent_file::end()
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{
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return upper_bound;
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}
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my_off_t Transparent_file::read_next()
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{
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size_t bytes_read;
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/*
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No need to seek here, as the file managed by Transparent_file class
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always points to upper_bound byte
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*/
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if ((bytes_read= my_read(filedes, buff, buff_size, MYF(0))) == MY_FILE_ERROR)
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return (my_off_t) -1;
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/* end of file */
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if (!bytes_read)
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return (my_off_t) -1;
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lower_bound= upper_bound;
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upper_bound+= bytes_read;
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return lower_bound;
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}
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char Transparent_file::get_value(my_off_t offset)
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{
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size_t bytes_read;
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/* check boundaries */
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if ((lower_bound <= offset) && (((my_off_t) offset) < upper_bound))
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return buff[offset - lower_bound];
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VOID(my_seek(filedes, offset, MY_SEEK_SET, MYF(0)));
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/* read appropriate portion of the file */
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if ((bytes_read= my_read(filedes, buff, buff_size,
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MYF(0))) == MY_FILE_ERROR)
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return 0;
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lower_bound= offset;
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upper_bound= lower_bound + bytes_read;
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/* end of file */
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if (upper_bound == (my_off_t) offset)
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return 0;
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return buff[0];
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}
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