path: root/libidn/stringprep.c

/* stringprep.c --- Core stringprep implementation.
 * Copyright (C) 2002, 2003, 2004  Simon Josefsson
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * GNU Libidn 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GNU Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>
#include <string.h>

#include "stringprep.h"

static ssize_t
stringprep_find_character_in_table (uint32_t ucs4,
				    const Stringprep_table_element * table)
{
  ssize_t i;

  /* This is where typical uses of Libidn spends very close to all CPU
     time and causes most cache misses.  One could easily do a binary
     search instead.  Before rewriting this, I want hard evidence this
     slowness is at all relevant in typical applications.  (I don't
     dispute optimization may improve matters significantly, I'm
     mostly interested in having someone give real-world benchmark on
     the impact of libidn.) */

  for (i = 0; table[i].start || table[i].end; i++)
    if (ucs4 >= table[i].start &&
	ucs4 <= (table[i].end ? table[i].end : table[i].start))
      return i;

  return -1;
}

static ssize_t
stringprep_find_string_in_table (uint32_t * ucs4,
				 size_t ucs4len,
				 size_t * tablepos,
				 const Stringprep_table_element * table)
{
  size_t j;
  ssize_t pos;

  for (j = 0; j < ucs4len; j++)
    if ((pos = stringprep_find_character_in_table (ucs4[j], table)) != -1)
      {
	if (tablepos)
	  *tablepos = pos;
	return j;
      }

  return -1;
}

static int
stringprep_apply_table_to_string (uint32_t * ucs4,
				  size_t * ucs4len,
				  size_t maxucs4len,
				  const Stringprep_table_element * table)
{
  ssize_t pos;
  size_t i, maplen;

  while ((pos = stringprep_find_string_in_table (ucs4, *ucs4len,
						 &i, table)) != -1)
    {
      for (maplen = STRINGPREP_MAX_MAP_CHARS;
	   maplen > 0 && table[i].map[maplen - 1] == 0; maplen--)
	;

      if (*ucs4len - 1 + maplen >= maxucs4len)
	return STRINGPREP_TOO_SMALL_BUFFER;

      memmove (&ucs4[pos + maplen], &ucs4[pos + 1],
	       sizeof (uint32_t) * (*ucs4len - pos - 1));
      memcpy (&ucs4[pos], table[i].map, sizeof (uint32_t) * maplen);
      *ucs4len = *ucs4len - 1 + maplen;
    }