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Sourcecode: alsa-utils version File versions

init_utils_string.c

/*
 * Copyright (C) 2004-2005 Kay Sievers <kay.sievers@vrfy.org>
 *
 *    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  02110-1301, USA.
 *
 */


static int string_is_true(const char *str)
{
      if (strcasecmp(str, "true") == 0)
            return 1;
      if (strcasecmp(str, "yes") == 0)
            return 1;
      if (strcasecmp(str, "1") == 0)
            return 1;
      return 0;
}

static void remove_trailing_chars(char *path, char c)
{
      size_t len;

      len = strlen(path);
      while (len > 0 && path[len-1] == c)
            path[--len] = '\0';
}

/* count of characters used to encode one unicode char */
static int utf8_encoded_expected_len(const char *str)
{
      unsigned char c = (unsigned char)str[0];

      if (c < 0x80)
            return 1;
      if ((c & 0xe0) == 0xc0)
            return 2;
      if ((c & 0xf0) == 0xe0)
            return 3;
      if ((c & 0xf8) == 0xf0)
            return 4;
      if ((c & 0xfc) == 0xf8)
            return 5;
      if ((c & 0xfe) == 0xfc)
            return 6;
      return 0;
}

/* decode one unicode char */
static int utf8_encoded_to_unichar(const char *str)
{
      int unichar;
      int len;
      int i;

      len = utf8_encoded_expected_len(str);
      switch (len) {
      case 1:
            return (int)str[0];
      case 2:
            unichar = str[0] & 0x1f;
            break;
      case 3:
            unichar = (int)str[0] & 0x0f;
            break;
      case 4:
            unichar = (int)str[0] & 0x07;
            break;
      case 5:
            unichar = (int)str[0] & 0x03;
            break;
      case 6:
            unichar = (int)str[0] & 0x01;
            break;
      default:
            return -1;
      }

      for (i = 1; i < len; i++) {
            if (((int)str[i] & 0xc0) != 0x80)
                  return -1;
            unichar <<= 6;
            unichar |= (int)str[i] & 0x3f;
      }

      return unichar;
}

/* expected size used to encode one unicode char */
static int utf8_unichar_to_encoded_len(int unichar)
{
      if (unichar < 0x80)
            return 1;
      if (unichar < 0x800)
            return 2;
      if (unichar < 0x10000)
            return 3;
      if (unichar < 0x200000)
            return 4;
      if (unichar < 0x4000000)
            return 5;
      return 6;
}

/* check if unicode char has a valid numeric range */
static int utf8_unichar_valid_range(int unichar)
{
      if (unichar > 0x10ffff)
            return 0;
      if ((unichar & 0xfffff800) == 0xd800)
            return 0;
      if ((unichar > 0xfdcf) && (unichar < 0xfdf0))
            return 0;
      if ((unichar & 0xffff) == 0xffff)
            return 0;
      return 1;
}

/* validate one encoded unicode char and return its length */
static int utf8_encoded_valid_unichar(const char *str)
{
      int len;
      int unichar;
      int i;

      len = utf8_encoded_expected_len(str);
      if (len == 0)
            return -1;

      /* ascii is valid */
      if (len == 1)
            return 1;

      /* check if expected encoded chars are available */
      for (i = 0; i < len; i++)
            if ((str[i] & 0x80) != 0x80)
                  return -1;

      unichar = utf8_encoded_to_unichar(str);

      /* check if encoded length matches encoded value */
      if (utf8_unichar_to_encoded_len(unichar) != len)
            return -1;

      /* check if value has valid range */
      if (!utf8_unichar_valid_range(unichar))
            return -1;

      return len;
}

/* replace everything but whitelisted plain ascii and valid utf8 */
static int replace_untrusted_chars(char *str)
{
      size_t i = 0;
      int replaced = 0;

      while (str[i] != '\0') {
            int len;

            /* valid printable ascii char */
            if ((str[i] >= '0' && str[i] <= '9') ||
                (str[i] >= 'A' && str[i] <= 'Z') ||
                (str[i] >= 'a' && str[i] <= 'z') ||
                strchr(" #$%+-./:=?@_,", str[i])) {
                  i++;
                  continue;
            }
            /* valid utf8 is accepted */
            len = utf8_encoded_valid_unichar(&str[i]);
            if (len > 1) {
                  i += len;
                  continue;
            }

            /* everything else is garbage */
            str[i] = '_';
            i++;
            replaced++;
      }

      return replaced;
}

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