~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems, Inc.

 *

 *  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 "quote.h"

namespace drizzled

{

inline

static uint32_t get_esc_bit(unsigned char *mask, unsigned char num)

{

  return (1 & (*((mask) + ((num) >> 3))) >> ((num) & 7));

}

/**

 * @brief

 *   Returns the argument string in single quotes suitable for using in a SQL statement.

 * 

 * @detail

 *   Adds a \\ before all characters that needs to be escaped in a SQL string.

 *   We also escape '^Z' (END-OF-FILE in windows) to avoid problems when

 *   running commands from a file in windows.

 * 

 *   This function is very useful when you want to generate SQL statements.

 *

 * @note

 *   val_str(NULL) returns the string 'NULL' (4 letters, without quotes).

 *

 * @retval str Quoted string

 * @retval NULL Out of memory.

 */

String *Item_func_quote::val_str(String *str)

{

  assert(fixed == 1);

  /*

    Bit mask that has 1 for set for the position of the following characters:

    0, \, ' and ^Z

  */

  static unsigned char escmask[32]=

  {

    0x01, 0x00, 0x00, 0x04, 0x80, 0x00, 0x00, 0x00,

    0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00,

    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

  };

  char *from, *to, *end, *start;

  String *arg= args[0]->val_str(str);

  uint32_t arg_length, new_length;

  if (!arg)					// Null argument

  {

    /* Return the string 'NULL' */

    str->copy(STRING_WITH_LEN("NULL"), collation.collation);

    null_value= 0;

    return str;

  }

  arg_length= arg->length();

  new_length= arg_length+2; /* for beginning and ending ' signs */

  for (from= (char*) arg->ptr(), end= from + arg_length; from < end; from++)

    new_length+= get_esc_bit(escmask, (unsigned char) *from);

  if (tmp_value.alloc(new_length))

    goto null;

  /*

    We replace characters from the end to the beginning

  */

  to= (char*) tmp_value.ptr() + new_length - 1;

  *to--= '\'';

  for (start= (char*) arg->ptr(),end= start + arg_length; end-- != start; to--)

  {

    /*

      We can't use the bitmask here as we want to replace \O and ^Z with 0

      and Z

    */

    switch (*end)  {

    case 0:

      *to--= '0';

      *to=   '\\';

      break;

    case '\032':

      *to--= 'Z';

      *to=   '\\';

      break;

    case '\'':

    case '\\':

      *to--= *end;

      *to=   '\\';

      break;

    default:

      *to= *end;

      break;

    }

  }

  *to= '\'';

  tmp_value.length(new_length);

  tmp_value.set_charset(collation.collation);

  null_value= 0;

  return &tmp_value;

null:

  null_value= 1;

  return 0;

}

} /* namespace drizzled */