~drizzle-trunk/drizzle/development

/* 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 <my_global.h>

#include <my_sys.h>

#include <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

*/

my_bool my_compress(uchar *packet, size_t *len, size_t *complen)

{

  DBUG_ENTER("my_compress");

  if (*len < MIN_COMPRESS_LENGTH)

  {

    *complen=0;

    DBUG_PRINT("note",("Packet too short: Not compressed"));

  }

  else

  {

    uchar *compbuf=my_compress_alloc(packet,len,complen);

    if (!compbuf)

      DBUG_RETURN(*complen ? 0 : 1);

    memcpy(packet,compbuf,*len);

    my_free(compbuf,MYF(MY_WME));

  }

  DBUG_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));

    DBUG_PRINT("note",("Packet got longer on compression; Not compressed"));

    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.

*/

my_bool my_uncompress(uchar *packet, size_t len, size_t *complen)

{

  uLongf tmp_complen;

  DBUG_ENTER("my_uncompress");

  if (*complen)					/* If compressed */

  {

    uchar *compbuf= (uchar *) my_malloc(*complen,MYF(MY_WME));

    int error;

    if (!compbuf)

      DBUG_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 */

      DBUG_PRINT("error",("Can't uncompress packet, error: %d",error));

      my_free(compbuf, MYF(MY_WME));

      DBUG_RETURN(1);

    }

    memcpy(packet, compbuf, *complen);

    my_free(compbuf, MYF(MY_WME));

  }

  else

    *complen= len;

  DBUG_RETURN(0);

}