content: /*
   * Copyright (c) 2016, 2021, Oracle and/or its affiliates.
   *
   * This program is free software; you can redistribute it and/or modify it under
   * the terms of the GNU General Public License, version 2.0, as published by the
   * Free Software Foundation.
   *
   * This program is also distributed with certain software (including but not
   * limited to OpenSSL) that is licensed under separate terms, as designated in a
   * particular file or component or in included license documentation. The
   * authors of MySQL hereby grant you an additional permission to link the
   * program and your derivative works with the separately licensed software that
   * they have included with MySQL.
   *
   * Without limiting anything contained in the foregoing, this file, which is
   * part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
   * version 1.0, a copy of which can be found at
   * http://oss.oracle.com/licenses/universal-foss-exception.
   *
   * 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, version 2.0,
   * 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
   */
  
  package com.mysql.cj.protocol.a;
  
  import com.mysql.cj.MysqlType;
  import com.mysql.cj.protocol.ColumnDefinition;
  import com.mysql.cj.protocol.ProtocolEntityFactory;
  import com.mysql.cj.protocol.ProtocolEntityReader;
  import com.mysql.cj.protocol.a.NativeConstants.IntegerDataType;
  import com.mysql.cj.result.Field;
  import com.mysql.cj.util.LazyString;
  
  public class ColumnDefinitionReader implements ProtocolEntityReader<ColumnDefinition, NativePacketPayload> {
  
      private NativeProtocol protocol;
  
      public ColumnDefinitionReader(NativeProtocol prot) {
          this.protocol = prot;
      }
  
      @Override
      public ColumnDefinition read(ProtocolEntityFactory<ColumnDefinition, NativePacketPayload> sf) {
  
          ColumnDefinitionFactory cdf = (ColumnDefinitionFactory) sf;
  
          long columnCount = cdf.getColumnCount();
          ColumnDefinition cdef = cdf.getColumnDefinitionFromCache();
  
          if (cdef != null && !cdf.mergeColumnDefinitions()) {
              for (int i = 0; i < columnCount; i++) {
                  this.protocol.skipPacket();
              }
              return cdef;
          }
  
          /* read the metadata from the server */
          Field[] fields = null;
          boolean checkEOF = !this.protocol.getServerSession().isEOFDeprecated();
  
          // Read in the column information
  
          fields = new Field[(int) columnCount];
  
          for (int i = 0; i < columnCount; i++) {
              NativePacketPayload fieldPacket = this.protocol.readMessage(null);
              // next check is needed for SSPS
              if (checkEOF && fieldPacket.isEOFPacket()) {
                  break;
              }
              fields[i] = unpackField(fieldPacket, this.protocol.getServerSession().getCharsetSettings().getMetadataEncoding());
          }
  
          return cdf.createFromFields(fields);
      }
  
      /**
       * Unpacks the Field information from the given packet.
       * 
       * @param packet
       *            the packet containing the field information
       * @param characterSetMetadata
       *            encoding of the metadata in the packet
       * 
       * @return the unpacked field
       */
      protected Field unpackField(NativePacketPayload packet, String characterSetMetadata) {
          int offset, length;
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          packet.setPosition(packet.getPosition() + length); // skip database name
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          offset = packet.getPosition();
          LazyString databaseName = new LazyString(packet.getByteBuffer(), offset, length, characterSetMetadata);
          packet.setPosition(packet.getPosition() + length);
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          offset = packet.getPosition();
          LazyString tableName = new LazyString(packet.getByteBuffer(), offset, length, characterSetMetadata);
          packet.setPosition(packet.getPosition() + length);
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          offset = packet.getPosition();
          LazyString originalTableName = new LazyString(packet.getByteBuffer(), offset, length, characterSetMetadata);
          packet.setPosition(packet.getPosition() + length);
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          offset = packet.getPosition();
          LazyString columnName = new LazyString(packet.getByteBuffer(), offset, length, characterSetMetadata);
          packet.setPosition(packet.getPosition() + length);
  
          length = (int) packet.readInteger(IntegerDataType.INT_LENENC);
          offset = packet.getPosition();
          LazyString originalColumnName = new LazyString(packet.getByteBuffer(), offset, length, characterSetMetadata);
          packet.setPosition(packet.getPosition() + length);
  
          packet.readInteger(IntegerDataType.INT1);
  
          short collationIndex = (short) packet.readInteger(IntegerDataType.INT2);
          long colLength = packet.readInteger(IntegerDataType.INT4);
          int colType = (int) packet.readInteger(IntegerDataType.INT1);
          short colFlag = (short) packet.readInteger(this.protocol.getServerSession().hasLongColumnInfo() ? IntegerDataType.INT2 : IntegerDataType.INT1);
          int colDecimals = (int) packet.readInteger(IntegerDataType.INT1);
  
          String encoding = this.protocol.getServerSession().getCharsetSettings().getJavaEncodingForCollationIndex(collationIndex);
  
          MysqlType mysqlType = NativeProtocol.findMysqlType(this.protocol.getPropertySet(), colType, colFlag, colLength, tableName, originalTableName,
                  collationIndex, encoding);
  
          // Protocol returns precision and scale differently for some types. We need to align then to I_S.
          switch (mysqlType) {
              case TINYINT:
              case TINYINT_UNSIGNED:
              case SMALLINT:
              case SMALLINT_UNSIGNED:
              case MEDIUMINT:
              case MEDIUMINT_UNSIGNED:
              case INT:
              case INT_UNSIGNED:
              case BIGINT:
              case BIGINT_UNSIGNED:
              case BOOLEAN:
                  colLength = mysqlType.getPrecision().intValue();
                  break;
  
              case DECIMAL:
                  colLength--;
                  if (colDecimals > 0) {
                      colLength--;
                  }
                  break;
              case DECIMAL_UNSIGNED:
                  if (colDecimals > 0) {
                      colLength--;
                  }
                  break;
              case FLOAT:
              case FLOAT_UNSIGNED:
              case DOUBLE:
              case DOUBLE_UNSIGNED:
                  // According to SQL standard, NUMERIC_SCALE should be NULL for approximate numeric data types.
                  // DECIMAL_NOT_SPECIFIED=31 is the MySQL internal constant value used to indicate that NUMERIC_SCALE is not applicable.
                  // It's probably a mistake that it's exposed by protocol as a decimals and it should be replaced with 0. 
                  if (colDecimals == 31) {
                      colDecimals = 0;
                  }
                  break;
  
              default:
                  break;
          }
  
          return new Field(databaseName, tableName, originalTableName, columnName, originalColumnName, colLength, colType, colFlag, colDecimals, collationIndex,
                  encoding, mysqlType);
      }
  
  }
  