content: /*
   * Copyright (c) 2016, 2020, 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.result;
  
  import com.mysql.cj.Messages;
  import com.mysql.cj.MysqlType;
  import com.mysql.cj.exceptions.ExceptionFactory;
  import com.mysql.cj.exceptions.ExceptionInterceptor;
  import com.mysql.cj.exceptions.WrongArgumentException;
  import com.mysql.cj.protocol.ColumnDefinition;
  import com.mysql.cj.protocol.ValueDecoder;
  import com.mysql.cj.protocol.a.NativeConstants.IntegerDataType;
  import com.mysql.cj.protocol.a.NativeConstants.StringLengthDataType;
  import com.mysql.cj.protocol.a.NativeConstants.StringSelfDataType;
  import com.mysql.cj.protocol.a.NativePacketPayload;
  import com.mysql.cj.protocol.a.NativeUtils;
  import com.mysql.cj.result.Row;
  import com.mysql.cj.result.ValueFactory;
  
  /**
   * A BufferRow implementation that holds one row packet from a server-side prepared statement (which is re-used by the driver,
   * and thus saves memory allocations), and tries when possible to avoid allocations to break out the results as individual byte[]s.
   * Rows from a server-side prepared statement are encoded differently, so we have different ways of finding where each column is, and
   * unpacking them.
   * 
   * (this isn't possible when doing things like reading floating point values).
   */
  public class BinaryBufferRow extends AbstractBufferRow {
  
      /**
       * The home position before the is-null bitmask for server-side prepared statement result sets
       */
      private int preNullBitmaskHomePosition = 0;
  
      /**
       * If binary-encoded, the NULL status of each column is at the beginning of the row, so we
       */
      private boolean[] isNull;
  
      public BinaryBufferRow(NativePacketPayload buf, ColumnDefinition cd, ExceptionInterceptor exceptionInterceptor, ValueDecoder valueDecoder) {
          super(exceptionInterceptor);
  
          this.rowFromServer = buf;
          this.homePosition = this.rowFromServer.getPosition();
          this.preNullBitmaskHomePosition = this.homePosition;
          this.valueDecoder = valueDecoder;
  
          if (cd.getFields() != null) {
              setMetadata(cd);
          }
      }
  
      @Override
      public boolean isBinaryEncoded() {
          return true;
      }
  
      @Override
      protected int findAndSeekToOffset(int index) {
          if (index == 0) {
              this.lastRequestedIndex = 0;
              this.lastRequestedPos = this.homePosition;
              this.rowFromServer.setPosition(this.homePosition);
  
              return 0;
          }
  
          if (index == this.lastRequestedIndex) {
              this.rowFromServer.setPosition(this.lastRequestedPos);
  
              return this.lastRequestedPos;
          }
  
          int startingIndex = 0;
  
          if (index > this.lastRequestedIndex) {
              if (this.lastRequestedIndex >= 0) {
                  startingIndex = this.lastRequestedIndex;
              } else {
                  // First-time "scan"
                  startingIndex = 0;
                  this.lastRequestedPos = this.homePosition;
              }
  
              this.rowFromServer.setPosition(this.lastRequestedPos);
          } else {
              this.rowFromServer.setPosition(this.homePosition);
          }
  
          for (int i = startingIndex; i < index; i++) {
              if (this.isNull[i]) {
                  continue;
              }
  
              int type = this.metadata.getFields()[i].getMysqlTypeId();
  
              if (type != MysqlType.FIELD_TYPE_NULL) {
                  int length = NativeUtils.getBinaryEncodedLength(this.metadata.getFields()[i].getMysqlTypeId());
                  if (length == 0) {
                      this.rowFromServer.skipBytes(StringSelfDataType.STRING_LENENC);
                  } else if (length == -1) {
                      throw ExceptionFactory.createException(Messages.getString("MysqlIO.97", new Object[] { type, i + 1, this.metadata.getFields().length }),
                              this.exceptionInterceptor);
                  } else {
                      int curPosition = this.rowFromServer.getPosition();
                      this.rowFromServer.setPosition(curPosition + length);
                  }
              }
          }
  
          this.lastRequestedIndex = index;
          this.lastRequestedPos = this.rowFromServer.getPosition();
  
          return this.lastRequestedPos;
      }
  
      @Override
      public byte[] getBytes(int index) {
          findAndSeekToOffset(index);
  
          if (this.getNull(index)) {
              return null;
          }
  
          int type = this.metadata.getFields()[index].getMysqlTypeId();
  
          switch (type) {
              case MysqlType.FIELD_TYPE_NULL:
                  return null;
  
              case MysqlType.FIELD_TYPE_TINY:
                  return this.rowFromServer.readBytes(StringLengthDataType.STRING_FIXED, 1);
  
              default:
                  int length = NativeUtils.getBinaryEncodedLength(type);
                  if (length == 0) {
                      return this.rowFromServer.readBytes(StringSelfDataType.STRING_LENENC);
                  } else if (length == -1) {
                      throw ExceptionFactory.createException(Messages.getString("MysqlIO.97", new Object[] { type, index + 1, this.metadata.getFields().length }),
                              this.exceptionInterceptor);
                  } else {
                      return this.rowFromServer.readBytes(StringLengthDataType.STRING_FIXED, length);
                  }
          }
      }
  
      /**
       * Check whether a column is NULL and update the 'wasNull' status.
       */
      @Override
      public boolean getNull(int columnIndex) {
          this.wasNull = this.isNull[columnIndex];
          return this.wasNull;
      }
  
      @Override
      public Row setMetadata(ColumnDefinition f) {
          super.setMetadata(f);
          setupIsNullBitmask();
          return this;
      }
  
      /**
       * Unpacks the bitmask at the head of the row packet that tells us what
       * columns hold null values, and sets the "home" position directly after the
       * bitmask.
       */
      private void setupIsNullBitmask() {
          if (this.isNull != null) {
              return; // we've already done this
          }
  
          this.rowFromServer.setPosition(this.preNullBitmaskHomePosition);
  
          int len = this.metadata.getFields().length;
          int nullCount = (len + 9) / 8;
  
          byte[] nullBitMask = this.rowFromServer.readBytes(StringLengthDataType.STRING_FIXED, nullCount);
  
          this.homePosition = this.rowFromServer.getPosition();
  
          this.isNull = new boolean[len];
  
          int nullMaskPos = 0;
          int bit = 4; // first two bits are reserved for future use
  
          for (int i = 0; i < len; i++) {
  
              this.isNull[i] = ((nullBitMask[nullMaskPos] & bit) != 0);
  
              if (((bit <<= 1) & 255) == 0) {
                  bit = 1; /* To next byte */
  
                  nullMaskPos++;
              }
          }
      }
  
      /**
       * Implementation of getValue() based on the underlying Buffer object. Delegate to superclass for decoding.
       */
      @Override
      public <T> T getValue(int columnIndex, ValueFactory<T> vf) {
          findAndSeekToOffset(columnIndex);
  
          // field length is type-specific in binary-encoded results
          int type = this.metadata.getFields()[columnIndex].getMysqlTypeId();
          int length = NativeUtils.getBinaryEncodedLength(type);
          if (!getNull(columnIndex)) {
              if (length == 0) {
                  length = (int) this.rowFromServer.readInteger(IntegerDataType.INT_LENENC);
              } else if (length == -1) {
                  throw ExceptionFactory.createException(
                          Messages.getString("MysqlIO.97", new Object[] { type, columnIndex + 1, this.metadata.getFields().length }), this.exceptionInterceptor);
              }
          }
          return getValueFromBytes(columnIndex, this.rowFromServer.getByteBuffer(), this.rowFromServer.getPosition(), length, vf);
      }
  
      @Override
      public void setBytes(int columnIndex, byte[] value) {
  
          byte[] backup = null;
          int backupLength = 0;
  
          // backup the rest of bytes
          if (columnIndex + 1 < this.metadata.getFields().length) {
              findAndSeekToOffset(columnIndex + 1);
              backupLength = this.rowFromServer.getPayloadLength() - this.rowFromServer.getPosition();
              backup = new byte[backupLength];
              System.arraycopy(this.rowFromServer.getByteBuffer(), this.rowFromServer.getPosition(), backup, 0, backupLength);
          }
  
          // write the replacement value
          findAndSeekToOffset(columnIndex);
          this.rowFromServer.setPayloadLength(this.rowFromServer.getPosition());
  
          if (value == null) {
              this.metadata.getFields()[columnIndex].setMysqlTypeId(MysqlType.FIELD_TYPE_NULL);
          } else {
              int type = this.metadata.getFields()[columnIndex].getMysqlTypeId();
  
              int length = NativeUtils.getBinaryEncodedLength(type);
              if (length == 0) {
                  this.rowFromServer.writeBytes(StringSelfDataType.STRING_LENENC, value);
              } else if (length == -1) {
                  throw ExceptionFactory.createException(
                          Messages.getString("MysqlIO.97", new Object[] { type, columnIndex + 1, this.metadata.getFields().length }), this.exceptionInterceptor);
              } else {
                  // write leading zeroes if value length < required length
                  if (length != value.length) {
                      throw ExceptionFactory.createException(WrongArgumentException.class, "Value length doesn't match the expected one for type " + type,
                              this.exceptionInterceptor);
                  }
                  // write value
                  this.rowFromServer.writeBytes(StringLengthDataType.STRING_FIXED, value);
              }
          }
  
          if (backup != null) {
              this.rowFromServer.writeBytes(StringLengthDataType.STRING_FIXED, backup);
          }
      }
  }
  