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bson/bson-utf8.c  view on Meta::CPAN

       */
      if (!seq_length) {
         return false;
      }

      /*
       * Ensure we have enough bytes left.
       */
      if ((utf8_len - i) < seq_length) {
         return false;
      }

      /*
       * Also calculate the next char as a unichar so we can
       * check code ranges for non-shortest form.
       */
      c = utf8 [i] & first_mask;

      /*
       * Check the high-bits for each additional sequence byte.
       */
      for (j = i + 1; j < (i + seq_length); j++) {
         c = (c << 6) | (utf8 [j] & 0x3F);
         if ((utf8[j] & 0xC0) != 0x80) {
            return false;
         }
      }

      /*
       * Check for NULL bytes afterwards.
       *
       * Hint: if you want to optimize this function, starting here to do
       * this in the same pass as the data above would probably be a good
       * idea. You would add a branch into the inner loop, but save possibly
       * on cache-line bouncing on larger strings. Just a thought.
       */
      if (!allow_null) {
         for (j = 0; j < seq_length; j++) {
            if (((i + j) > utf8_len) || !utf8[i + j]) {
               return false;
            }
         }
      }

      /*
       * Code point wont fit in utf-16, not allowed.
       */
      if (c > 0x0010FFFF) {
         return false;
      }

      /*
       * Byte is in reserved range for UTF-16 high-marks
       * for surrogate pairs.
       */
      if ((c & 0xFFFFF800) == 0xD800) {
         return false;
      }

      /*
       * Check non-shortest form unicode.
       */
      switch (seq_length) {
      case 1:
         if (c <= 0x007F) {
            continue;
         }
         return false;

      case 2:
         if ((c >= 0x0080) && (c <= 0x07FF)) {
            continue;
         } else if (c == 0) {
            /* Two-byte representation for NULL. */
            continue;
         }
         return false;

      case 3:
         if (((c >= 0x0800) && (c <= 0x0FFF)) ||
             ((c >= 0x1000) && (c <= 0xFFFF))) {
            continue;
         }
         return false;

      case 4:
         if (((c >= 0x10000) && (c <= 0x3FFFF)) ||
             ((c >= 0x40000) && (c <= 0xFFFFF)) ||
             ((c >= 0x100000) && (c <= 0x10FFFF))) {
            continue;
         }
         return false;

      default:
         return false;
      }
   }

   return true;
}


/*
 *--------------------------------------------------------------------------
 *
 * bson_utf8_escape_for_json --
 *
 *       Allocates a new string matching @utf8 except that special
 *       characters in JSON will be escaped. The resulting string is also
 *       UTF-8 encoded.
 *
 *       Both " and \ characters will be escaped. Additionally, if a NUL
 *       byte is found before @utf8_len bytes, it will be converted to the
 *       two byte UTF-8 sequence.
 *
 * Parameters:
 *       @utf8: A UTF-8 encoded string.
 *       @utf8_len: The length of @utf8 in bytes or -1 if NUL terminated.
 *
 * Returns:
 *       A newly allocated string that should be freed with bson_free().