mariadb/sql-common/pack.c

/* Copyright (c) 2000-2003, 2007 MySQL AB
   Use is subject to license terms

   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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */

#include <my_global.h>
#include <mysql_com.h>
#include <mysql.h>

/* Get the length of next field. Change parameter to point at fieldstart */
ulong net_field_length(uchar **packet)
{
  reg1 uchar *pos= (uchar *)*packet;
  if (*pos < 251)
  {
    (*packet)++;
    return (ulong) *pos;
  }
  if (*pos == 251)
  {
    (*packet)++;
    return NULL_LENGTH;
  }
  if (*pos == 252)
  {
    (*packet)+=3;
    return (ulong) uint2korr(pos+1);
  }
  if (*pos == 253)
  {
    (*packet)+=4;
    return (ulong) uint3korr(pos+1);
  }
  (*packet)+=9;					/* Must be 254 when here */
  return (ulong) uint4korr(pos+1);
}

/* The same as above but returns longlong */
my_ulonglong net_field_length_ll(uchar **packet)
{
  uchar *pos= *packet;
  if (*pos < 251)
  {
    (*packet)++;
    return (my_ulonglong) *pos;
  }
  if (*pos == 251)
  {
    (*packet)++;
    return (my_ulonglong) NULL_LENGTH;
  }
  if (*pos == 252)
  {
    (*packet)+=3;
    return (my_ulonglong) uint2korr(pos+1);
  }
  if (*pos == 253)
  {
    (*packet)+=4;
    return (my_ulonglong) uint3korr(pos+1);
  }
  DBUG_ASSERT(*pos == 254);
  (*packet)+=9;					/* Must be 254 when here */
  return (my_ulonglong) uint8korr(pos+1);
}

my_ulonglong safe_net_field_length_ll(uchar **packet, size_t packet_len)
{
  uchar *pos= *packet;
  if (packet_len < 1)
    goto err;
  if (*pos < 251)
  {
    (*packet)++;
    return (my_ulonglong) *pos;
  }
  if (*pos == 251)
  {
    (*packet)++;
    return (my_ulonglong) NULL_LENGTH;
  }
  if (*pos == 252)
  {
    if (packet_len < 3)
      goto err;
    (*packet)+=3;
    return (my_ulonglong) uint2korr(pos+1);
  }
  if (*pos == 253)
  {
    if (packet_len < 4)
      goto err;
    (*packet)+=4;
    return (my_ulonglong) uint3korr(pos+1);
  }
  if (packet_len < 9 || *pos != 254)
    goto err;
  (*packet)+=9;
  return (my_ulonglong) uint8korr(pos+1);
err:
  *packet = NULL;
  return 0;
}

/*
  Store an integer with simple packing into a output package

  SYNOPSIS
    net_store_length()
    packet              Store the packed integer here
    length		integers to store

  NOTES
    This is mostly used to store lengths of strings.

  RETURN
   Position in 'packet' after the packed length
*/

uchar *net_store_length(uchar *packet, ulonglong length)
{
  if (length < 251)
  {
    *packet= (uchar) length;
    return packet+1;
  }
  /* 251 is reserved for NULL */
  if (length < 65536)
  {
    *packet++=252;
    int2store(packet, (uint) length);
    return packet+2;
  }
  if (length < 16777216)
  {
    *packet++=253;
    int3store(packet, (ulong) length);
    return packet+3;
  }
  *packet++=254;
  int8store(packet,length);
  return packet+8;
}

uchar *safe_net_store_length(uchar *packet, size_t packet_len, ulonglong length)
{
  if (length < 251)
  {
    if (packet_len < 1)
      return NULL;
    *packet= (uchar) length;
    return packet+1;
  }
  /* 251 is reserved for NULL */
  if (length < 65536)
  {
    if (packet_len < 3)
      return NULL;
    *packet++=252;
    int2store(packet, (uint) length);
    return packet+2;
  }
  if (length < 16777216)
  {
    if (packet_len < 4)
      return NULL;
    *packet++=253;
    int3store(packet, (ulong) length);
    return packet+3;
  }
  if (packet_len < 9)
    return NULL;
  *packet++=254;
  int8store(packet,length);
  return packet+8;
}


/**
  The length of space required to store the resulting length-encoded integer
  for the given number. This function can be used at places where one needs to
  dynamically allocate the buffer for a given number to be stored as length-
  encoded integer.

  @param num [IN]   the input number

  @return length of buffer needed to store this number [1, 3, 4, 9].
*/

uint net_length_size(ulonglong num)
{
  if (num < (ulonglong) 251LL)
    return 1;
  if (num < (ulonglong) 65536LL)
    return 3;
  if (num < (ulonglong) 16777216LL)
    return 4;
  return 9;
}