mcs/class/Npgsql/Npgsql/NpgsqlAsciiRow.cs

   1 // created on 13/6/2002 at 21:06
   2
   3 // Npgsql.NpgsqlAsciiRow.cs
   4 //
   5 // Author:
   6 //      Francisco Jr. (fxjrlists@yahoo.com.br)
   7 //
   8 //      Copyright (C) 2002 The Npgsql Development Team
   9 //      npgsql-general@gborg.postgresql.org
  10 //      http://gborg.postgresql.org/project/npgsql/projdisplay.php
  11 //
  12 // This library is free software; you can redistribute it and/or
  13 // modify it under the terms of the GNU Lesser General Public
  14 // License as published by the Free Software Foundation; either
  15 // version 2.1 of the License, or (at your option) any later version.
  16 //
  17 // This library is distributed in the hope that it will be useful,
  18 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 // Lesser General Public License for more details.
  21 //
  22 // You should have received a copy of the GNU Lesser General Public
  23 // License along with this library; if not, write to the Free Software
  24 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  25
  26 using System;
  27 using System.Collections;
  28 using System.IO;
  29 using System.Text;
  30 using System.Net;
  31 using NpgsqlTypes;
  32
  33
  34 namespace Npgsql
  35 {
  36
  37     /// <summary>
  38     /// This class represents the AsciiRow (version 2) and DataRow (version 3+)
  39     /// message sent from the PostgreSQL server.
  40     /// </summary>
  41     internal sealed class NpgsqlAsciiRow : NpgsqlRow
  42     {
  43         // Logging related values
  44         private static readonly String CLASSNAME = "NpgsqlAsciiRow";
  45
  46         private readonly Int16        READ_BUFFER_SIZE = 300; //[FIXME] Is this enough??
  47         private Hashtable             oid_to_name_mapping;
  48
  49         public NpgsqlAsciiRow(NpgsqlRowDescription rowDesc, Hashtable oidToNameMapping, ProtocolVersion protocolVersion)
  50         : base(rowDesc, protocolVersion)
  51         {
  52             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, CLASSNAME);
  53
  54             oid_to_name_mapping = oidToNameMapping;
  55         }
  56
  57         public override void ReadFromStream(Stream inputStream, Encoding encoding)
  58         {
  59             switch (protocol_version) {
  60             case ProtocolVersion.Version2 :
  61                 ReadFromStream_Ver_2(inputStream, encoding);
  62                 break;
  63
  64             case ProtocolVersion.Version3 :
  65                 ReadFromStream_Ver_3(inputStream, encoding);
  66                 break;
  67
  68             }
  69         }
  70
  71         private void ReadFromStream_Ver_2(Stream inputStream, Encoding encoding)
  72         {
  73             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "ReadFromStream_Ver_2");
  74
  75             Byte[]       input_buffer = new Byte[READ_BUFFER_SIZE];
  76             Byte[]       null_map_array = new Byte[(row_desc.NumFields + 7)/8];
  77
  78             Array.Clear(null_map_array, 0, null_map_array.Length);
  79
  80             // Read the null fields bitmap.
  81             PGUtil.CheckedStreamRead(inputStream, null_map_array, 0, null_map_array.Length );
  82
  83             // Get the data.
  84             for (Int16 field_count = 0; field_count < row_desc.NumFields; field_count++)
  85             {
  86                 // Check if this field is null
  87                 if (IsBackendNull(null_map_array, field_count))
  88                 {
  89                     data.Add(DBNull.Value);
  90                     continue;
  91                 }
  92
  93                 // Read the first data of the first row.
  94
  95                 PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, 4);
  96
  97                 Int32 field_value_size = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(input_buffer, 0));
  98                 field_value_size -= 4;
  99                 Int32 bytes_left = field_value_size;
 100
 101                 StringBuilder result = new StringBuilder();
 102
 103                 while (bytes_left > READ_BUFFER_SIZE)
 104                 {
 105                     // Now, read just the field value.
 106                     PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, READ_BUFFER_SIZE);
 107
 108                     // Read the bytes as string.
 109                     result.Append(new String(encoding.GetChars(input_buffer, 0, READ_BUFFER_SIZE)));
 110
 111                     bytes_left -= READ_BUFFER_SIZE;
 112                 }
 113
 114                 // Now, read just the field value.
 115                 PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, bytes_left);
 116
 117                 // Read the bytes as string.
 118                 result.Append(new String(encoding.GetChars(input_buffer, 0, bytes_left)));
 119
 120
 121                 // Add them to the AsciiRow data.
 122                 data.Add(NpgsqlTypesHelper.ConvertBackendStringToSystemType(oid_to_name_mapping, result.ToString(), row_desc[field_count].type_oid, row_desc[field_count].type_modifier));
 123
 124             }
 125         }
 126
 127         private void ReadFromStream_Ver_3(Stream inputStream, Encoding encoding)
 128         {
 129             NpgsqlEventLog.LogMethodEnter(LogLevel.Debug, CLASSNAME, "ReadFromStream_Ver_3");
 130
 131             Byte[] input_buffer = new Byte[READ_BUFFER_SIZE];
 132
 133             PGUtil.ReadInt32(inputStream, input_buffer);
 134             Int16 numCols = PGUtil.ReadInt16(inputStream, input_buffer);
 135
 136             for (Int16 field_count = 0; field_count < numCols; field_count++)
 137             {
 138                 Int32 field_value_size = PGUtil.ReadInt32(inputStream, input_buffer);
 139
 140                 // Check if this field is null
 141                 if (field_value_size == -1) // Null value
 142                 {
 143                     data.Add(DBNull.Value);
 144                     continue;
 145                 }
 146
 147                 Int32           bytes_left = field_value_size;
 148                 StringBuilder   result = new StringBuilder();
 149
 150                 while (bytes_left > READ_BUFFER_SIZE)
 151                 {
 152                     // Now, read just the field value.
 153                     PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, READ_BUFFER_SIZE);
 154
 155                     // Read the bytes as string.
 156                     result.Append(new String(encoding.GetChars(input_buffer, 0, READ_BUFFER_SIZE)));
 157
 158                     bytes_left -= READ_BUFFER_SIZE;
 159                 }
 160
 161                 // Now, read just the field value.
 162                 PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, bytes_left);
 163
 164                 if (row_desc[field_count].format_code == FormatCode.Text)
 165                 {
 166                     // Read the bytes as string.
 167                     result.Append(new String(encoding.GetChars(input_buffer, 0, bytes_left)));
 168                     // Add them to the AsciiRow data.
 169                     data.Add(NpgsqlTypesHelper.ConvertBackendStringToSystemType(oid_to_name_mapping, result.ToString(), row_desc[field_count].type_oid, row_desc[field_count].type_modifier));
 170                 }
 171                 else
 172                     data.Add(NpgsqlTypesHelper.ConvertBackendBytesToStytemType(oid_to_name_mapping, input_buffer, encoding, field_value_size, row_desc[field_count].type_oid, row_desc[field_count].type_modifier));
 173             }
 174         }
 175
 176         // Using the given null field map (provided by the backend),
 177         // determine if the given field index is mapped null by the backend.
 178         // We only need to do this for version 2 protocol.
 179         private static Boolean IsBackendNull(Byte[] null_map_array, Int32 index)
 180         {
 181             // Get the byte that holds the bit index position.
 182             Byte test_byte = null_map_array[index/8];
 183
 184             // Now, check if index bit is set.
 185             // To do this, get its position in the byte, shift to
 186             // MSB and test it with the byte 10000000.
 187             return (((test_byte << (index%8)) & 0x80) == 0);
 188         }
 189     }
 190 }