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Fix rowversion null behaviour #998

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merged 3 commits into from
Apr 14, 2021
Merged

Fix rowversion null behaviour #998

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7d480d9
Change SqlDataReader RowVersion/Timestamp null behaviour to match oth…
Wraith2 Mar 20, 2021
222e821
add test
Wraith2 Mar 28, 2021
fe9fdb7
rework positive test and add negative test
Wraith2 Apr 3, 2021
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26 changes: 18 additions & 8 deletions src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlDataReader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3732,16 +3732,26 @@ private bool TryReadColumnInternal(int i, bool readHeaderOnly = false)
_sharedState._nextColumnDataToRead = _sharedState._nextColumnHeaderToRead;
_sharedState._nextColumnHeaderToRead++; // We read this one

if (isNull && columnMetaData.type != SqlDbType.Timestamp)
if (isNull)
{
TdsParser.GetNullSqlValue(_data[_sharedState._nextColumnDataToRead],
columnMetaData,
_command != null ? _command.ColumnEncryptionSetting : SqlCommandColumnEncryptionSetting.UseConnectionSetting,
_parser.Connection);

if (!readHeaderOnly)
if (columnMetaData.type == SqlDbType.Timestamp)
{
_sharedState._nextColumnDataToRead++;
if (!LocalAppContextSwitches.LegacyRowVersionNullBehaviour)
{
_data[i].SetToNullOfType(SqlBuffer.StorageType.SqlBinary);
}
}
else
{
TdsParser.GetNullSqlValue(_data[_sharedState._nextColumnDataToRead],
columnMetaData,
_command != null ? _command.ColumnEncryptionSetting : SqlCommandColumnEncryptionSetting.UseConnectionSetting,
_parser.Connection);

if (!readHeaderOnly)
{
_sharedState._nextColumnDataToRead++;
}
}
}
else
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26 changes: 18 additions & 8 deletions src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/SqlDataReader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4279,16 +4279,26 @@ private bool TryReadColumnInternal(int i, bool readHeaderOnly = false)
_sharedState._nextColumnDataToRead = _sharedState._nextColumnHeaderToRead;
_sharedState._nextColumnHeaderToRead++; // We read this one

if (isNull && columnMetaData.type != SqlDbType.Timestamp /* Maintain behavior for known bug (Dev10 479607) rejected as breaking change - See comments in GetNullSqlValue for timestamp */)
if (isNull)
{
TdsParser.GetNullSqlValue(_data[_sharedState._nextColumnDataToRead],
columnMetaData,
_command != null ? _command.ColumnEncryptionSetting : SqlCommandColumnEncryptionSetting.UseConnectionSetting,
_parser.Connection);

if (!readHeaderOnly)
if (columnMetaData.type == SqlDbType.Timestamp)
{
_sharedState._nextColumnDataToRead++;
if (!LocalAppContextSwitches.LegacyRowVersionNullBehaviour)
{
_data[i].SetToNullOfType(SqlBuffer.StorageType.SqlBinary);
}
}
else
{
TdsParser.GetNullSqlValue(_data[_sharedState._nextColumnDataToRead],
columnMetaData,
_command != null ? _command.ColumnEncryptionSetting : SqlCommandColumnEncryptionSetting.UseConnectionSetting,
_parser.Connection);

if (!readHeaderOnly)
{
_sharedState._nextColumnDataToRead++;
}
}
}
else
Expand Down
26 changes: 26 additions & 0 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/LocalAppContextSwitches.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,11 @@ namespace Microsoft.Data.SqlClient
internal static partial class LocalAppContextSwitches
{
internal const string MakeReadAsyncBlockingString = @"Switch.Microsoft.Data.SqlClient.MakeReadAsyncBlocking";
internal const string LegacyRowVersionNullString = @"Switch.Microsoft.Data.SqlClient.LegacyRowVersionNullBehaviour";

private static bool _makeReadAsyncBlocking;
private static bool? s_legacyRowVersionNullBehaviour;

public static bool MakeReadAsyncBlocking
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand All @@ -19,5 +23,27 @@ public static bool MakeReadAsyncBlocking
return AppContext.TryGetSwitch(MakeReadAsyncBlockingString, out _makeReadAsyncBlocking) ? _makeReadAsyncBlocking : false;
}
}

/// <summary>
/// In System.Data.SqlClient and Microsoft.Data.SqlClient prior to 3.0.0 a field with type Timestamp/RowVersion
/// would return an empty byte array. This switch contols whether to preserve that behaviour on newer versions
/// of Microsoft.Data.SqlClient, if this switch returns false an appropriate null value will be returned
/// </summary>
public static bool LegacyRowVersionNullBehaviour
{
get
{
if (s_legacyRowVersionNullBehaviour == null)
{
bool value = false;
if (AppContext.TryGetSwitch(LegacyRowVersionNullString, out bool providedValue))
{
value = providedValue;
}
s_legacyRowVersionNullBehaviour = value;
}
return s_legacyRowVersionNullBehaviour.Value;
}
}
}
}