System.Data.SqlClient.TdsParser.TryCommonProcessMetaData C# (CSharp) Метод

        private bool TryCommonProcessMetaData(TdsParserStateObject stateObj, _SqlMetaData col)
        {
            byte byteLen;
            UInt32 userType;

            // read user type - 4 bytes Yukon, 2 backwards
            if (!stateObj.TryReadUInt32(out userType))
            {
                return false;
            }

            // read flags and set appropriate flags in structure
            byte flags;
            if (!stateObj.TryReadByte(out flags))
            {
                return false;
            }

            col.updatability = (byte)((flags & TdsEnums.Updatability) >> 2);
            col.isNullable = (TdsEnums.Nullable == (flags & TdsEnums.Nullable));
            col.isIdentity = (TdsEnums.Identity == (flags & TdsEnums.Identity));

            // read second byte of column metadata flags
            if (!stateObj.TryReadByte(out flags))
            {
                return false;
            }


            byte tdsType;
            if (!stateObj.TryReadByte(out tdsType))
            {
                return false;
            }

            if (tdsType == TdsEnums.SQLXMLTYPE)
                col.length = TdsEnums.SQL_USHORTVARMAXLEN;  //Use the same length as other plp datatypes
            else if (IsVarTimeTds(tdsType))
                col.length = 0;  // placeholder until we read the scale, just make sure it's not SQL_USHORTVARMAXLEN
            else if (tdsType == TdsEnums.SQLDATE)
            {
                col.length = 3;
            }
            else
            {
                if (!TryGetTokenLength(tdsType, stateObj, out col.length))
                {
                    return false;
                }
            }

            col.metaType = MetaType.GetSqlDataType(tdsType, userType, col.length);
            col.type = col.metaType.SqlDbType;

            col.tdsType = (col.isNullable ? col.metaType.NullableType : col.metaType.TDSType);

            {
                if (TdsEnums.SQLUDT == tdsType)
                {
                    if (!TryProcessUDTMetaData((SqlMetaDataPriv)col, stateObj))
                    {
                        return false;
                    }
                }

                if (col.length == TdsEnums.SQL_USHORTVARMAXLEN)
                {
                    Debug.Assert(tdsType == TdsEnums.SQLXMLTYPE ||
                                 tdsType == TdsEnums.SQLBIGVARCHAR ||
                                 tdsType == TdsEnums.SQLBIGVARBINARY ||
                                 tdsType == TdsEnums.SQLNVARCHAR ||
                                 tdsType == TdsEnums.SQLUDT,
                                 "Invalid streaming datatype");
                    col.metaType = MetaType.GetMaxMetaTypeFromMetaType(col.metaType);
                    Debug.Assert(col.metaType.IsLong, "Max datatype not IsLong");
                    col.length = Int32.MaxValue;
                    if (tdsType == TdsEnums.SQLXMLTYPE)
                    {
                        byte schemapresent;
                        if (!stateObj.TryReadByte(out schemapresent))
                        {
                            return false;
                        }

                        if ((schemapresent & 1) != 0)
                        {
                            if (!stateObj.TryReadByte(out byteLen))
                            {
                                return false;
                            }
                            if (byteLen != 0)
                            {
                                if (!stateObj.TryReadString(byteLen, out col.xmlSchemaCollectionDatabase))
                                {
                                    return false;
                                }
                            }

                            if (!stateObj.TryReadByte(out byteLen))
                            {
                                return false;
                            }
                            if (byteLen != 0)
                            {
                                if (!stateObj.TryReadString(byteLen, out col.xmlSchemaCollectionOwningSchema))
                                {
                                    return false;
                                }
                            }

                            short shortLen;
                            if (!stateObj.TryReadInt16(out shortLen))
                            {
                                return false;
                            }
                            if (byteLen != 0)
                            {
                                if (!stateObj.TryReadString(shortLen, out col.xmlSchemaCollectionName))
                                {
                                    return false;
                                }
                            }
                        }
                    }
                }
            }

            if (col.type == SqlDbType.Decimal)
            {
                if (!stateObj.TryReadByte(out col.precision))
                {
                    return false;
                }
                if (!stateObj.TryReadByte(out col.scale))
                {
                    return false;
                }
            }

            if (col.metaType.IsVarTime)
            {
                if (!stateObj.TryReadByte(out col.scale))
                {
                    return false;
                }

                Debug.Assert(0 <= col.scale && col.scale <= 7);

                // calculate actual column length here
                switch (col.metaType.SqlDbType)
                {
                    case SqlDbType.Time:
                        col.length = MetaType.GetTimeSizeFromScale(col.scale);
                        break;
                    case SqlDbType.DateTime2:
                        // Date in number of days (3 bytes) + time
                        col.length = 3 + MetaType.GetTimeSizeFromScale(col.scale);
                        break;
                    case SqlDbType.DateTimeOffset:
                        // Date in days (3 bytes) + offset in minutes (2 bytes) + time
                        col.length = 5 + MetaType.GetTimeSizeFromScale(col.scale);
                        break;

                    default:
                        Debug.Assert(false, "Unknown VariableTime type!");
                        break;
                }
            }

            // read the collation for 7.x servers
            if (col.metaType.IsCharType && (tdsType != TdsEnums.SQLXMLTYPE))
            {
                if (!TryProcessCollation(stateObj, out col.collation))
                {
                    return false;
                }

                int codePage = GetCodePage(col.collation, stateObj);

                if (codePage == _defaultCodePage)
                {
                    col.codePage = _defaultCodePage;
                    col.encoding = _defaultEncoding;
                }
                else
                {
                    col.codePage = codePage;
                    col.encoding = System.Text.Encoding.GetEncoding(col.codePage);
                }
            }

            if (col.metaType.IsLong && !col.metaType.IsPlp)
            {
                int unusedLen = 0xFFFF;      //We ignore this value
                if (!TryProcessOneTable(stateObj, ref unusedLen, out col.multiPartTableName))
                {
                    return false;
                }
            }

            if (!stateObj.TryReadByte(out byteLen))
            {
                return false;
            }
            if (!stateObj.TryReadString(byteLen, out col.column))
            {
                return false;
            }

            // We get too many DONE COUNTs from the server, causing too many StatementCompleted event firings.
            // We only need to fire this event when we actually have a meta data stream with 0 or more rows.
            stateObj._receivedColMetaData = true;
            return true;
        }