Application Exception happens instead of FbException when Firebird service is stopped. [DNET324] #335
Comments
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Commented by: A. Murat Ozdemiray (ozdemiray) I analyzed the problem by debugging from 2.7.0 source code. GdsTransaction.BeginTransaction method calls GdsDatabase.ReadGenericResponse method (line 152) which returns null to "response" variable. Then BeginTransaction method tries to use this "response" variable which causes a NullReferenceException. To go deeper in the call stack, ReadGenericResponse method reads an unexpected operation code from XdrStream.ReadOperation method, which eventually calls XdrStream.ReadBytes method returns which could read nothing from the underlying stream but returns successfully as if it read something, because first call to Read method returns 0 and loop do not continue to run, since currentlyRead = 0. So although nothing is read from the stream, the method returns the empty buffer (which is full of 0s). public byte[] ReadBytes(int count) In order to fix the problem in my case, I added following lines to before the return statement; if(toRead > 0 && toRead == count) and InvalidOperationException is catched in GdsTransaction.BeginTransaction method |
Modified by: @cincuranetstatus: Open [ 1 ] => In Progress [ 3 ] |
Modified by: @cincuranetstatus: In Progress [ 3 ] => Resolved [ 5 ] resolution: Fixed [ 1 ] Fix Version: 2.7-next [ 10462 ] |
Submitted by: @luronumen
Votes: 1
ACTUAL RESULT: Application Exception happens instead of FbException when Firebird service is stopped.
EXPECTED RESULT: An FbException should happen instead of Application Exception.
STEPS TO REPRODUCE THIS ISSUE:
1- Start Firebird service and connect with a database [fbConnection].
2- Execute a valid data reader [fbCommand.ExecuteReader()] or Non Query [fbCommand.ExecuteNonQuery()]:
Verify that no error happens;
3- Stop Firebird Service and repeat the same procedure from step 2
ISSUE: An application exception happens instead of an FbException:
***************************************************************************************************************
System.NullReferenceException: Object reference not set to an instance of an object.
at FirebirdSql.Data.Client.Managed.Version10.GdsTransaction.BeginTransaction(TransactionParameterBuffer tpb)
at FirebirdSql.Data.Client.Managed.Version10.GdsDatabase.BeginTransaction(TransactionParameterBuffer tpb)
at FirebirdSql.Data.FirebirdClient.FbTransaction.BeginTransaction()
at FirebirdSql.Data.FirebirdClient.FbCommand.Prepare(Boolean returnsSet)
at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteCommand(CommandBehavior behavior, Boolean returnsSet)
at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteCommand(CommandBehavior behavior)
at FirebirdSql.Data.FirebirdClient.FbCommand.ExecuteNonQuery()
***************************************************************************************************************
Example:
try
{
FbCommand fbCommand = new FbCommand(cmdText, fbConnection);
fbCommand.CommandType = CommandType.Text;
FbDataReader fbDataReader = fbCommand.ExecuteReader();
return fbDataReader;
}
catch (FbException ex)
{
/*THIS EXCEPTION SHOULD GET HERE*/
if (ex.Errors[ex.Errors.Count - 1].Number == 335544726)
MessageBox.Show("Connection to Server Lost.", "ERROR");
}
ENVIRONMENT
- http://ADO.NET Data Provider Version: 05-Jun-2010 19:07 - http://netprovider.cincura.net/FirebirdSql.Data.FirebirdClient.dll;
- Windows 7 Ultimate;
- Microsoft Visual C# 2010 Express;
- Firebird 2.5.0.25920 Release candidate 2;
Commits: f3c3e35
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