System.Data.Common.DataRecordInternal.GetBytes C# (CSharp) Method

        public override long GetBytes(int i, long dataIndex, byte[] buffer, int bufferIndex, int length)
        {
            int cbytes = 0;
            int ndataIndex;

            byte[] data = (byte[])_values[i];

            cbytes = data.Length;

            // since arrays can't handle 64 bit values and this interface doesn't
            // allow chunked access to data, a dataIndex outside the rang of Int32
            // is invalid
            if (dataIndex > int.MaxValue)
            {
                throw ADP.InvalidSourceBufferIndex(cbytes, dataIndex, nameof(dataIndex));
            }

            ndataIndex = (int)dataIndex;

            // if no buffer is passed in, return the number of characters we have
            if (null == buffer)
                return cbytes;

            try
            {
                if (ndataIndex < cbytes)
                {
                    // help the user out in the case where there's less data than requested
                    if ((ndataIndex + length) > cbytes)
                        cbytes = cbytes - ndataIndex;
                    else
                        cbytes = length;
                }

                // until arrays are 64 bit, we have to do these casts
                Array.Copy(data, ndataIndex, buffer, bufferIndex, cbytes);
            }
            catch (Exception e) when (ADP.IsCatchableExceptionType(e))
            {
                cbytes = data.Length;

                if (length < 0)
                {
                    throw ADP.InvalidDataLength(length);
                }

                // if bad buffer index, throw
                if (bufferIndex < 0 || bufferIndex >= buffer.Length)
                {
                    throw ADP.InvalidDestinationBufferIndex(length, bufferIndex, nameof(bufferIndex));
                }

                // if bad data index, throw
                if (dataIndex < 0 || dataIndex >= cbytes)
                {
                    throw ADP.InvalidSourceBufferIndex(length, dataIndex, nameof(dataIndex));
                }

                // if there is not enough room in the buffer for data
                if (cbytes + bufferIndex > buffer.Length)
                {
                    throw ADP.InvalidBufferSizeOrIndex(cbytes, bufferIndex);
                }
            }

            return cbytes;
        }