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/* btree_util.h: common macros/functions in the Btree implementation.
*
* ----START-LICENCE----
* Copyright 1999,2000,2001 BrightStation PLC
* Copyright 2002,2004 Olly Betts
*
* 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; either version 2 of the
* License, or (at your option) any later version.
*
* 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
* -----END-LICENCE-----
*/
#ifndef OM_HGUARD_BTREE_UTIL_H
#define OM_HGUARD_BTREE_UTIL_H
#include "quartz_types.h"
#include "omassert.h"
#include <string.h> /* memset */
/* The unit of access into the DB files is an unsigned char, which is defined
as 'byte' with a typedef.
Other integer values are built up from these bytes, either in pairs or fours.
'int2' and 'int4' are signed types which will comfortably accommodate
all 2 byte and 4 byte ranges:
*/
/*
If a signed int cannot hold the full range of two bytes replace 'int' by
'long' throughout the code.
FIXME: surely if a signed int cannot hold the full range of two bytes,
then the compiler violates ANSI? Or am I misunderstanding...
*/
// FIXME: 65536 in Asserts below should really be block_size
inline int
GETINT1(const byte *p, int c)
{
Assert(c >= 0);
Assert(c < 65536);
return p[c];
}
inline void
SETINT1(byte *p, int c, int x)
{
Assert(c >= 0);
Assert(c < 65536);
p[c] = x;
}
inline int
GETINT2(const byte *p, int c)
{
Assert(c >= 0);
Assert(c + 1 < 65536);
return p[c] << 8 | p[c + 1];
}
inline void
SETINT2(byte *p, int c, int x)
{
Assert(c >= 0);
Assert(c + 1 < 65536);
p[c] = x >> 8;
p[c + 1] = x;
}
inline int
get_int4(const byte *p, int c)
{
Assert(c >= 0);
Assert(c + 3 < 65536);
return p[c] << 24 | p[c + 1] << 16 | p[c + 2] << 8 | p[c + 3];
}
inline void
set_int4(byte *p, int c, int x)
{
Assert(c >= 0);
Assert(c + 3 < 65536);
p[c] = x >> 24;
p[c + 1] = x >> 16;
p[c + 2] = x >> 8;
p[c + 3] = x;
}
int sys_open_to_read(const string & name);
int sys_open_to_read_no_except(const string & name);
int sys_open_to_write(const string & name);
void sys_unlink_if_exists(const string &filename);
// Return true on success
inline bool sys_close(int h) {
return close(h) == 0;
}
string sys_read_all_bytes(int h, size_t max);
void sys_write_string(int h, const string &s);
int sys_flush(int h);
inline byte *zeroed_new(size_t size)
{
byte *temp = new byte[size];
if (temp) memset(temp, 0, size);
return temp;
}
/** A tiny class used to close a filehandle safely in the presence
* of exceptions.
*/
class fdcloser {
public:
fdcloser(int fd_) : fd(fd_) {}
~fdcloser() {
if (fd >= 0) {
sys_close(fd);
}
}
private:
int fd;
};
#endif /* OM_HGUARD_BTREE_UTIL_H */
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