field_conv.cc

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/* Copyright (C) 2000-2003 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */


#include <config.h>

#include <drizzled/error.h>
#include <drizzled/table.h>
#include <drizzled/session.h>
#include <drizzled/current_session.h>

#include <drizzled/copy_field.h>
#include <drizzled/field/blob.h>
#include <drizzled/field/date.h>
#include <drizzled/field/datetime.h>
#include <drizzled/field/decimal.h>
#include <drizzled/field/double.h>
#include <drizzled/field/enum.h>
#include <drizzled/field/epoch.h>
#include <drizzled/field/int32.h>
#include <drizzled/field/int64.h>
#include <drizzled/field/null.h>
#include <drizzled/field/num.h>
#include <drizzled/field/num.h>
#include <drizzled/field/real.h>
#include <drizzled/field/str.h>
#include <drizzled/field/varstring.h>
#include <drizzled/util/test.h>
#include <drizzled/system_variables.h>

namespace drizzled {

static void do_field_eq(CopyField *copy)
{
  memcpy(copy->to_ptr, copy->from_ptr, copy->from_length);
}

static void do_field_1(CopyField *copy)
{
  copy->to_ptr[0]= copy->from_ptr[0];
}

static void do_field_2(CopyField *copy)
{
  copy->to_ptr[0]= copy->from_ptr[0];
  copy->to_ptr[1]= copy->from_ptr[1];
}

static void do_field_3(CopyField *copy)
{
  copy->to_ptr[0]= copy->from_ptr[0];
  copy->to_ptr[1]= copy->from_ptr[1];
  copy->to_ptr[2]= copy->from_ptr[2];
}

static void do_field_4(CopyField *copy)
{
  copy->to_ptr[0]= copy->from_ptr[0];
  copy->to_ptr[1]= copy->from_ptr[1];
  copy->to_ptr[2]= copy->from_ptr[2];
  copy->to_ptr[3]= copy->from_ptr[3];
}

static void do_field_6(CopyField *copy)
{                  // For blob field
  copy->to_ptr[0]= copy->from_ptr[0];
  copy->to_ptr[1]= copy->from_ptr[1];
  copy->to_ptr[2]= copy->from_ptr[2];
  copy->to_ptr[3]= copy->from_ptr[3];
  copy->to_ptr[4]= copy->from_ptr[4];
  copy->to_ptr[5]= copy->from_ptr[5];
}

static void do_field_8(CopyField *copy)
{
  copy->to_ptr[0]= copy->from_ptr[0];
  copy->to_ptr[1]= copy->from_ptr[1];
  copy->to_ptr[2]= copy->from_ptr[2];
  copy->to_ptr[3]= copy->from_ptr[3];
  copy->to_ptr[4]= copy->from_ptr[4];
  copy->to_ptr[5]= copy->from_ptr[5];
  copy->to_ptr[6]= copy->from_ptr[6];
  copy->to_ptr[7]= copy->from_ptr[7];
}


static void do_field_to_null_str(CopyField *copy)
{
  if (*copy->from_null_ptr & copy->from_bit)
  {
    memset(copy->to_ptr, 0, copy->from_length);
    copy->to_null_ptr[0]= 1;  // Always bit 1
  }
  else
  {
    copy->to_null_ptr[0]= 0;
    memcpy(copy->to_ptr, copy->from_ptr, copy->from_length);
  }
}


static void do_outer_field_to_null_str(CopyField *copy)
{
  if (*copy->null_row ||
      (copy->from_null_ptr && (*copy->from_null_ptr & copy->from_bit)))
  {
    memset(copy->to_ptr, 0, copy->from_length);
    copy->to_null_ptr[0]= 1;  // Always bit 1
  }
  else
  {
    copy->to_null_ptr[0]= 0;
    memcpy(copy->to_ptr, copy->from_ptr, copy->from_length);
  }
}


int
set_field_to_null(Field *field)
{
  if (field->real_maybe_null())
  {
    field->set_null();
    field->reset();
    return 0;
  }
  field->reset();
  if (field->getTable()->in_use->count_cuted_fields == CHECK_FIELD_WARN)
  {
    field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN, ER_WARN_DATA_TRUNCATED, 1);
    return 0;
  }
  if (!field->getTable()->in_use->no_errors)
    my_error(ER_BAD_NULL_ERROR, MYF(0), field->field_name);
  return -1;
}


int
set_field_to_null_with_conversions(Field *field, bool no_conversions)
{
  if (field->real_maybe_null())
  {
    field->set_null();
    field->reset();
    return 0;
  }

  if (no_conversions)
    return -1;

  /*
    Check if this is a special type, which will get a special walue
    when set to NULL (TIMESTAMP fields which allow setting to NULL
    are handled by first check).
  */
  if (field->is_timestamp())
  {
    ((field::Epoch::pointer) field)->set_time();
    return 0;         // Ok to set time to NULL
  }

  field->reset();
  if (field == field->getTable()->next_number_field)
  {
    field->getTable()->auto_increment_field_not_null= false;
    return 0;         // field is set in fill_record()
  }

  if (field->getTable()->in_use->count_cuted_fields == CHECK_FIELD_WARN)
  {
    field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN, ER_BAD_NULL_ERROR, 1);
    return 0;
  }

  if (!field->getTable()->in_use->no_errors)
    my_error(ER_BAD_NULL_ERROR, MYF(0), field->field_name);

  return -1;
}


static void do_skip(CopyField *)
{
}


static void do_copy_null(CopyField *copy)
{
  if (*copy->from_null_ptr & copy->from_bit)
  {
    *copy->to_null_ptr|= copy->to_bit;
    copy->to_field->reset();
  }
  else
  {
    *copy->to_null_ptr&= ~copy->to_bit;
    (copy->do_copy2)(copy);
  }
}


static void do_outer_field_null(CopyField *copy)
{
  if (*copy->null_row ||
      (copy->from_null_ptr && (*copy->from_null_ptr & copy->from_bit)))
  {
    *copy->to_null_ptr|=copy->to_bit;
    copy->to_field->reset();
  }
  else
  {
    *copy->to_null_ptr&= ~copy->to_bit;
    (copy->do_copy2)(copy);
  }
}


static void do_copy_not_null(CopyField *copy)
{
  if (copy->to_field->hasDefault() and *copy->from_null_ptr & copy->from_bit)
  {
    copy->to_field->set_default();
  }
  else if (*copy->from_null_ptr & copy->from_bit)
  {
    copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                ER_WARN_DATA_TRUNCATED, 1);
    copy->to_field->reset();
  }
  else
  {
    (copy->do_copy2)(copy);
  }
}


static void do_copy_maybe_null(CopyField *copy)
{
  *copy->to_null_ptr&= ~copy->to_bit;
  (copy->do_copy2)(copy);
}

/* timestamp and next_number has special handling in case of NULL values */

static void do_copy_timestamp(CopyField *copy)
{
  if (*copy->from_null_ptr & copy->from_bit)
  {
    /* Same as in set_field_to_null_with_conversions() */
    ((field::Epoch::pointer) copy->to_field)->set_time();
  }
  else
  {
    (copy->do_copy2)(copy);
  }
}


static void do_copy_next_number(CopyField *copy)
{
  if (*copy->from_null_ptr & copy->from_bit)
  {
    /* Same as in set_field_to_null_with_conversions() */
    copy->to_field->getTable()->auto_increment_field_not_null= false;
    copy->to_field->reset();
  }
  else
  {
    (copy->do_copy2)(copy);
  }
}


static void do_copy_blob(CopyField *copy)
{
  ulong length= ((Field_blob*) copy->from_field)->get_length();
  ((Field_blob*) copy->to_field)->store_length(length);
  memcpy(copy->to_ptr, copy->from_ptr, sizeof(char*));
}

static void do_conv_blob(CopyField *copy)
{
  copy->from_field->val_str_internal(&copy->tmp);
  ((Field_blob *) copy->to_field)->store(copy->tmp.ptr(),
                                         copy->tmp.length(),
                                         copy->tmp.charset());
}

static void do_save_blob(CopyField *copy)
{
  char buff[MAX_FIELD_WIDTH];
  String res(buff, sizeof(buff), copy->tmp.charset());
  copy->from_field->val_str_internal(&res);
  copy->tmp.copy(res);
  ((Field_blob *) copy->to_field)->store(copy->tmp.ptr(),
                                         copy->tmp.length(),
                                         copy->tmp.charset());
}


static void do_field_string(CopyField *copy)
{
  char buff[MAX_FIELD_WIDTH];
  copy->tmp.set_quick(buff,sizeof(buff),copy->tmp.charset());
  copy->from_field->val_str_internal(&copy->tmp);
  copy->to_field->store(copy->tmp.data(),copy->tmp.length(), copy->tmp.charset());
}


static void do_field_enum(CopyField *copy)
{
  if (copy->from_field->val_int() == 0)
    ((Field_enum *) copy->to_field)->store_type((uint64_t) 0);
  else
    do_field_string(copy);
}


static void do_field_int(CopyField *copy)
{
  int64_t value= copy->from_field->val_int();
  copy->to_field->store(value,
                        test(copy->from_field->flags & UNSIGNED_FLAG));
}

static void do_field_real(CopyField *copy)
{
  double value=copy->from_field->val_real();
  copy->to_field->store(value);
}


static void do_field_decimal(CopyField *copy)
{
  type::Decimal value;
  copy->to_field->store_decimal(copy->from_field->val_decimal(&value));
}


static void do_cut_string(CopyField *copy)
{
  const charset_info_st * const cs= copy->from_field->charset();
  memcpy(copy->to_ptr, copy->from_ptr, copy->to_length);

  /* Check if we loosed any important characters */
  if (cs->cset->scan(cs,
                     (char*) copy->from_ptr + copy->to_length,
                     (char*) copy->from_ptr + copy->from_length,
                     MY_SEQ_SPACES) < copy->from_length - copy->to_length)
  {
    copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                ER_WARN_DATA_TRUNCATED, 1);
  }
}


static void do_cut_string_complex(CopyField *copy)
{           // Shorter string field
  int well_formed_error;
  const charset_info_st * const cs= copy->from_field->charset();
  const unsigned char *from_end= copy->from_ptr + copy->from_length;
  uint32_t copy_length= cs->cset->well_formed_len(*cs, str_ref(copy->from_ptr, from_end), copy->to_length / cs->mbmaxlen, &well_formed_error);
  if (copy->to_length < copy_length)
    copy_length= copy->to_length;
  memcpy(copy->to_ptr, copy->from_ptr, copy_length);

  /* Check if we lost any important characters */
  if (well_formed_error ||
      cs->cset->scan(cs, (char*) copy->from_ptr + copy_length,
                     (char*) from_end,
                     MY_SEQ_SPACES) < (copy->from_length - copy_length))
  {
    copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                ER_WARN_DATA_TRUNCATED, 1);
  }

  if (copy_length < copy->to_length)
    cs->cset->fill(cs, (char*) copy->to_ptr + copy_length,
                   copy->to_length - copy_length, ' ');
}




static void do_expand_binary(CopyField *copy)
{
  const charset_info_st * const cs= copy->from_field->charset();
  memcpy(copy->to_ptr, copy->from_ptr, copy->from_length);
  cs->cset->fill(cs, (char*) copy->to_ptr+copy->from_length,
                 copy->to_length-copy->from_length, '\0');
}



static void do_expand_string(CopyField *copy)
{
  const charset_info_st * const cs= copy->from_field->charset();
  memcpy(copy->to_ptr,copy->from_ptr,copy->from_length);
  cs->cset->fill(cs, (char*) copy->to_ptr+copy->from_length,
                 copy->to_length-copy->from_length, ' ');
}


static void do_varstring1(CopyField *copy)
{
  uint32_t length= (uint32_t) *(unsigned char*) copy->from_ptr;
  if (length > copy->to_length- 1)
  {
    length= copy->to_length - 1;
    if (copy->from_field->getTable()->in_use->count_cuted_fields)
    {
      copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                  ER_WARN_DATA_TRUNCATED, 1);
    }
  }
  *(unsigned char*) copy->to_ptr= (unsigned char) length;
  memcpy(copy->to_ptr+1, copy->from_ptr + 1, length);
}


static void do_varstring1_mb(CopyField *copy)
{
  int well_formed_error;
  const charset_info_st * const cs= copy->from_field->charset();
  uint32_t from_length= (uint32_t) *(unsigned char*) copy->from_ptr;
  const unsigned char *from_ptr= copy->from_ptr + 1;
  uint32_t to_char_length= (copy->to_length - 1) / cs->mbmaxlen;
  uint32_t length= cs->cset->well_formed_len(*cs, str_ref(from_ptr, from_length), to_char_length, &well_formed_error);
  if (length < from_length)
  {
    if (current_session->count_cuted_fields)
    {
      copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN, ER_WARN_DATA_TRUNCATED, 1);
    }
  }
  *copy->to_ptr= (unsigned char) length;
  memcpy(copy->to_ptr + 1, from_ptr, length);
}


static void do_varstring2(CopyField *copy)
{
  uint32_t length= uint2korr(copy->from_ptr);
  if (length > copy->to_length- HA_KEY_BLOB_LENGTH)
  {
    length=copy->to_length-HA_KEY_BLOB_LENGTH;
    if (copy->from_field->getTable()->in_use->count_cuted_fields)
    {
      copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                  ER_WARN_DATA_TRUNCATED, 1);
    }
  }
  int2store(copy->to_ptr,length);
  memcpy(copy->to_ptr+HA_KEY_BLOB_LENGTH, copy->from_ptr + HA_KEY_BLOB_LENGTH,
         length);
}


static void do_varstring2_mb(CopyField *copy)
{
  int well_formed_error;
  const charset_info_st * const cs= copy->from_field->charset();
  uint32_t char_length= (copy->to_length - HA_KEY_BLOB_LENGTH) / cs->mbmaxlen;
  uint32_t from_length= uint2korr(copy->from_ptr);
  const unsigned char *from_beg= copy->from_ptr + HA_KEY_BLOB_LENGTH;
  uint32_t length= cs->cset->well_formed_len(*cs, str_ref(from_beg, from_length), char_length, &well_formed_error);
  if (length < from_length)
  {
    if (current_session->count_cuted_fields)
    {
      copy->to_field->set_warning(DRIZZLE_ERROR::WARN_LEVEL_WARN,
                                  ER_WARN_DATA_TRUNCATED, 1);
    }
  }
  int2store(copy->to_ptr, length);
  memcpy(copy->to_ptr+HA_KEY_BLOB_LENGTH, from_beg, length);
}


/***************************************************************************
** The different functions that fills in a CopyField class
***************************************************************************/

void CopyField::set(unsigned char *to,Field *from)
{
  from_ptr= from->ptr;
  to_ptr= to;
  from_length= from->pack_length();
  if (from->maybe_null())
  {
    from_null_ptr= from->null_ptr;
    from_bit= from->null_bit;
    to_ptr[0]= 1;                             // Null as default value
    to_null_ptr= (unsigned char*) to_ptr++;
    to_bit= 1;
    if (from->getTable()->maybe_null)
    {
      null_row= &from->getTable()->null_row;
      do_copy= do_outer_field_to_null_str;
    }
    else
      do_copy= do_field_to_null_str;
  }
  else
  {
    to_null_ptr= 0;                           // For easy debugging
    do_copy= do_field_eq;
  }
}


/*
  To do:

  If 'save\ is set to true and the 'from' is a blob field, do_copy is set to
  do_save_blob rather than do_conv_blob.  The only differences between them
  appears to be:

  - do_save_blob allocates and uses an intermediate buffer before calling
    Field_blob::store. Is this in order to trigger the call to
    well_formed_copy_nchars, by changing the pointer copy->tmp.ptr()?
    That call will take place anyway in all known cases.

  - The above causes a truncation to MAX_FIELD_WIDTH. Is this the intended
    effect? Truncation is handled by well_formed_copy_nchars anyway.
 */
void CopyField::set(Field *to,Field *from,bool save)
{
  if (to->type() == DRIZZLE_TYPE_NULL)
  {
    to_null_ptr= 0;           // For easy debugging
    to_ptr= 0;
    do_copy= do_skip;
    return;
  }
  from_field= from;
  to_field= to;
  from_ptr= from->ptr;
  from_length= from->pack_length();
  to_ptr= to->ptr;
  to_length= to_field->pack_length();

  // set up null handling
  from_null_ptr= to_null_ptr= 0;
  if (from->maybe_null())
  {
    from_null_ptr= from->null_ptr;
    from_bit= from->null_bit;
    if (to_field->real_maybe_null())
    {
      to_null_ptr= to->null_ptr;
      to_bit= to->null_bit;
      if (from_null_ptr)
      {
        do_copy= do_copy_null;
      }
      else
      {
        null_row= &from->getTable()->null_row;
        do_copy= do_outer_field_null;
      }
    }
    else
    {
      if (to_field->is_timestamp())
      {
        do_copy= do_copy_timestamp;               // Automatic timestamp
      }
      else if (to_field == to_field->getTable()->next_number_field)
      {
        do_copy= do_copy_next_number;
      }
      else
      {
        do_copy= do_copy_not_null;
      }
    }
  }
  else if (to_field->real_maybe_null())
  {
    to_null_ptr= to->null_ptr;
    to_bit= to->null_bit;
    do_copy= do_copy_maybe_null;
  }
  else
   do_copy= 0;

  if ((to->flags & BLOB_FLAG) && save)
    do_copy2= do_save_blob;
  else
    do_copy2= get_copy_func(to,from);
  if (!do_copy)         // Not null
    do_copy= do_copy2;
}


CopyField::Copy_func *
CopyField::get_copy_func(Field *to,Field *from)
{
  bool compatible_db_low_byte_first= (to->getTable()->getShare()->db_low_byte_first ==
                                     from->getTable()->getShare()->db_low_byte_first);
  if (to->flags & BLOB_FLAG)
  {
    if (!(from->flags & BLOB_FLAG) || from->charset() != to->charset())
      return do_conv_blob;
    if (from_length != to_length || !compatible_db_low_byte_first)
    {
      // Correct pointer to point at char pointer
      to_ptr+= to_length - to->getTable()->getShare()->sizeBlobPtr();
      from_ptr+= from_length- from->getTable()->getShare()->sizeBlobPtr();
      return do_copy_blob;
    }
  }
  else
  {
    if (to->result_type() == DECIMAL_RESULT)
      return do_field_decimal;
      
    // Check if identical fields
    if (from->result_type() == STRING_RESULT)
    {
      /*
        If we are copying date or datetime's we have to check the dates
        if we don't allow 'all' dates.
      */
      if (to->real_type() != from->real_type() ||
          !compatible_db_low_byte_first ||
          (((to->getTable()->in_use->variables.sql_mode & (MODE_NO_ZERO_DATE | MODE_INVALID_DATES)) && to->type() == DRIZZLE_TYPE_DATE) || to->type() == DRIZZLE_TYPE_DATETIME))
      {
        if (from->real_type() == DRIZZLE_TYPE_ENUM)
        {
          if (to->result_type() != STRING_RESULT)
          {
            return do_field_int;  // Convert SET to number
          }

          return do_field_string;
        }
      }

      if (to->real_type() == DRIZZLE_TYPE_ENUM)
      {
        if (!to->eq_def(from))
        {
          if (from->real_type() == DRIZZLE_TYPE_ENUM &&
              to->real_type() == DRIZZLE_TYPE_ENUM)
            return do_field_enum;
          else
            return do_field_string;
        }
      }
      else if (to->charset() != from->charset())
        return do_field_string;
      else if (to->real_type() == DRIZZLE_TYPE_VARCHAR)
      {
        /* Field_blob is not part of the Field_varstring hierarchy,
          and casting to varstring for calling pack_length_no_ptr()
          is always incorrect. Previously the below comparison has
          always evaluated to false as pack_length_no_ptr() for BLOB
          will return 4 and varstring can only be <= 2.
          If your brain slightly bleeds as to why this worked for
          so many years, you are in no way alone.
        */
        if (from->flags & BLOB_FLAG)
          return do_field_string;

        if ((static_cast<Field_varstring*>(to))->pack_length_no_ptr() !=
            (static_cast<Field_varstring*>(from))->pack_length_no_ptr())
        {
          return do_field_string;
        }

        if (to_length != from_length)
        {
          return (((Field_varstring*) to)->pack_length_no_ptr() == 1 ?
                  (from->charset()->mbmaxlen == 1 ? do_varstring1 :
                   do_varstring1_mb) :
                  (from->charset()->mbmaxlen == 1 ? do_varstring2 :
                   do_varstring2_mb));
        }
      }
      else if (to_length < from_length)
      {
        return (from->charset()->mbmaxlen == 1 ?
                do_cut_string : do_cut_string_complex);
      }
      else if (to_length > from_length)
      {
        if (to->charset() == &my_charset_bin)
          return do_expand_binary;
        else
          return do_expand_string;
      }
    }
    else if (to->real_type() != from->real_type() ||
             to_length != from_length ||
             !compatible_db_low_byte_first)
    {
      if (to->result_type() == STRING_RESULT)
        return do_field_string;
      if (to->result_type() == INT_RESULT)
        return do_field_int;

      return do_field_real;
    }
    else
    {
      if (!to->eq_def(from) || !compatible_db_low_byte_first)
      {
        if (to->result_type() == INT_RESULT)
          return do_field_int;
        else
          return do_field_real;
      }
    }
  }
  
    /* Eq fields */
  switch (to_length)
  {
  case 1: return do_field_1;
  case 2: return do_field_2;
  case 3: return do_field_3;
  case 4: return do_field_4;
  case 6: return do_field_6;
  case 8: return do_field_8;
  }
  
  return do_field_eq;
}


int field_conv(Field *to,Field *from)
{
  if (to->real_type() == from->real_type() &&
      !(to->type() == DRIZZLE_TYPE_BLOB && to->getTable()->copy_blobs))
  {
    /* Please god, will someone rewrite this to be readable :( */
    if (to->pack_length() == from->pack_length() &&
        !(to->flags & UNSIGNED_FLAG && !(from->flags & UNSIGNED_FLAG)) &&
        to->real_type() != DRIZZLE_TYPE_ENUM &&
        (to->real_type() != DRIZZLE_TYPE_DECIMAL || (to->field_length == from->field_length && (((Field_num*)to)->dec == ((Field_num*)from)->dec))) &&
        from->charset() == to->charset() &&
  to->getTable()->getShare()->db_low_byte_first == from->getTable()->getShare()->db_low_byte_first &&
        (!(to->getTable()->in_use->variables.sql_mode & (MODE_NO_ZERO_DATE | MODE_INVALID_DATES)) || (to->type() != DRIZZLE_TYPE_DATE && to->type() != DRIZZLE_TYPE_DATETIME)) &&
        (from->real_type() != DRIZZLE_TYPE_VARCHAR || ((Field_varstring*)from)->pack_length_no_ptr() == ((Field_varstring*)to)->pack_length_no_ptr()))
    {           // Identical fields
      /* This may happen if one does 'UPDATE ... SET x=x' */
      if (to->ptr != from->ptr)
        memcpy(to->ptr,from->ptr,to->pack_length());
      return 0;
    }
  }
  if (to->type() == DRIZZLE_TYPE_BLOB)
  {           // Be sure the value is stored
    Field_blob *blob=(Field_blob*) to;
    from->val_str_internal(&blob->value);
    /*
      Copy value if copy_blobs is set, or source is not a string and
      we have a pointer to its internal string conversion buffer.
    */
    if (to->getTable()->copy_blobs ||
        (!blob->value.is_alloced() &&
         from->real_type() != DRIZZLE_TYPE_VARCHAR))
      blob->value.copy();
    return blob->store(blob->value.ptr(),blob->value.length(),from->charset());
  }
  if (from->real_type() == DRIZZLE_TYPE_ENUM &&
      to->real_type() == DRIZZLE_TYPE_ENUM &&
      from->val_int() == 0)
  {
    ((Field_enum *)(to))->store_type(0);
    return 0;
  }
  else if ((from->result_type() == STRING_RESULT &&
            (to->result_type() == STRING_RESULT ||
             (from->real_type() != DRIZZLE_TYPE_ENUM))))
  {
    char buff[MAX_FIELD_WIDTH];
    String result(buff,sizeof(buff),from->charset());
    from->val_str_internal(&result);
    /*
      We use c_ptr_quick() here to make it easier if to is a float/double
      as the conversion routines will do a copy of the result doesn't
      end with \0. Can be replaced with .ptr() when we have our own
      string->double conversion.
    */
    return to->store(result.c_str(),result.length(),from->charset());
  }
  else if (from->result_type() == REAL_RESULT)
  {
    return to->store(from->val_real());
  }
  else if (from->result_type() == DECIMAL_RESULT)
  {
    type::Decimal buff;
    return to->store_decimal(from->val_decimal(&buff));
  }
  else
  {
    return to->store(from->val_int(), test(from->flags & UNSIGNED_FLAG));
  }
}

} /* namespace drizzled */