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/* Copyright (C) 2000 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 */
/* Written by Sinisa Milivojevic <sinisa@mysql.com> */
#include "mysys_priv.h"
#include <my_sys.h>
#include <mystrings/m_string.h>
#include <zlib.h>
/*
This replaces the packet with a compressed packet
SYNOPSIS
my_compress()
packet Data to compress. This is is replaced with the compressed data.
len Length of data to compress at 'packet'
complen out: 0 if packet was not compressed
RETURN
1 error. 'len' is not changed'
0 ok. In this case 'len' contains the size of the compressed packet
*/
bool my_compress(uchar *packet, size_t *len, size_t *complen)
{
if (*len < MIN_COMPRESS_LENGTH)
{
*complen=0;
}
else
{
uchar *compbuf=my_compress_alloc(packet,len,complen);
if (!compbuf)
return(*complen ? 0 : 1);
memcpy(packet,compbuf,*len);
my_free(compbuf,MYF(MY_WME));
}
return(0);
}
uchar *my_compress_alloc(const uchar *packet, size_t *len, size_t *complen)
{
uchar *compbuf;
uLongf tmp_complen;
int res;
*complen= *len * 120 / 100 + 12;
if (!(compbuf= (uchar *) my_malloc(*complen, MYF(MY_WME))))
return 0; /* Not enough memory */
tmp_complen= *complen;
res= compress((Bytef*) compbuf, &tmp_complen, (Bytef*) packet, (uLong) *len);
*complen= tmp_complen;
if (res != Z_OK)
{
my_free(compbuf, MYF(MY_WME));
return 0;
}
if (*complen >= *len)
{
*complen= 0;
my_free(compbuf, MYF(MY_WME));
return 0;
}
/* Store length of compressed packet in *len */
swap_variables(size_t, *len, *complen);
return compbuf;
}
/*
Uncompress packet
SYNOPSIS
my_uncompress()
packet Compressed data. This is is replaced with the orignal data.
len Length of compressed data
complen Length of the packet buffer (must be enough for the original
data)
RETURN
1 error
0 ok. In this case 'complen' contains the updated size of the
real data.
*/
bool my_uncompress(uchar *packet, size_t len, size_t *complen)
{
uLongf tmp_complen;
if (*complen) /* If compressed */
{
uchar *compbuf= (uchar *) my_malloc(*complen,MYF(MY_WME));
int error;
if (!compbuf)
return(1); /* Not enough memory */
tmp_complen= *complen;
error= uncompress((Bytef*) compbuf, &tmp_complen, (Bytef*) packet,
(uLong) len);
*complen= tmp_complen;
if (error != Z_OK)
{ /* Probably wrong packet */
my_free(compbuf, MYF(MY_WME));
return(1);
}
memcpy(packet, compbuf, *complen);
my_free(compbuf, MYF(MY_WME));
}
else
*complen= len;
return(0);
}
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