System.Data.SQLite

After switching from 1.0.40 to 1.0.41 following exception starts to occur at line

command.ExecuteNonQuery();

System.AccessViolationException occurred
Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
Source="System.Data.SQLite"
StackTrace:
at System.Data.SQLite.UnsafeNativeMethods.sqlite3_step_interop(IntPtr stmt)
at System.Data.SQLite.SQLite3.Step(SQLiteStatement stmt)
at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()

I need to see your code around that area.  Are you inadvertently disposing of any objects and using them afterwards, or trying to use objects across multiple threads?

Robert

 

for that example the surroundings will be

// somwere here transaction is started
IDbCommand com = connection.CreateCommand();
com.Transaction = trans;

com.CommandText = "Delete from KnownEntityTypes where id=@Id; Delete from KnownPropertyTypes where ENTITY_TYPE_ID=@Id; ";

DBUtils.addCommandParam(com, "@Id", type.Id); // my function to add parameter and set it value to type.Id that is Guid

com.ExecuteNonQuery(); // AccessViolation occurs


Also there is another exception, that occurs during first launch of application when database is just created

com.CommandText = "CREATE TABLE [Entity] (LOCAL_ID bigint NOT NULL , CHANGE_TYPE tinyint NULL , [Id] UNIQUEIDENTIFIER NULL , [Id$C] bit NOT NULL DEFAULT 0 , [LocalId] BIGINT NULL , [LocalId$C] bit NOT NULL DEFAULT 0 , [Version.TransactionId] UNIQUEIDENTIFIER NULL , [Version.TransactionId$C] bit NOT NULL DEFAULT 0 , [Version.Time] BIGINT NULL , [Version.Time$C] bit NOT NULL DEFAULT 0 , [Version.BaseVersionTime] BIGINT NULL , [Version.BaseVersionTime$C] bit NOT NULL DEFAULT 0 , [Version.MergedVersionTime] BIGINT NULL , [Version.MergedVersionTime$C] bit NOT NULL DEFAULT 0 , [Version.ChangedBy.Id] UNIQUEIDENTIFIER NULL , [Version.ChangedBy.Id$C] bit NOT NULL DEFAULT 0 , [Version.ChangedAtHost] UNIQUEIDENTIFIER NULL , [Version.ChangedAtHost$C] bit NOT NULL DEFAULT 0 , [Version.State] INT NULL , [Version.State$C] bit NOT NULL DEFAULT 0 , [Type.Id] UNIQUEIDENTIFIER NULL , [Type.Id$C] bit NOT NULL DEFAULT 0)";

com.ExecuteNonQuery();

System.NullReferenceException occurred
Message="Object reference not set to an instance of an object."
Source="System.Data.SQLite"
StackTrace:
at System.Data.SQLite.SQLiteStatement.Dispose()
at System.Data.SQLite.SQLite3.Reset(SQLiteStatement stmt)
at System.Data.SQLite.SQLite3.Step(SQLiteStatement stmt)
at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()
at

but if I execute command "CREATE TABLE [Entity] (LOCAL_ID bigint NOT NULL )" instead, no exception happens.

Also no exception happens if com.ExecuteNonQuery(); is executed second time

Would it be possible for you to send me your app via e-mail?  Preferably with debug symbols.

robert at blackcastlesoft dot com

 

I haven't yet succeeded in creating a test case application.

But I think there is a bug in SQLiteStatement.Dispose():

instead of

public void Dispose()
{
_sqlite_stmt.Dispose();
...
}

there should be

public void Dispose()
{
if (_sqlite_stmt!=null) _sqlite_stmt.Dispose();
...
}

because in SQLite3.Reset temp._sqlite_stmt is set to null in the using clause. And dispose is called on SQLiteStatement with null _sqlite_stmt


And regarding AccessViolationException: I run my app with debug version of SQLite - Exception occurs here:

internal override bool Step(SQLiteStatement stmt)
{
int n;
long timeout = 0;
Random rnd = null;

while (true)
{
n = UnsafeNativeMethods.sqlite3_step_interop(stmt._sqlite_stmt); // here stmt._sqlite_stmt.handle = 0 and stmt._sqlite_stmt.IsInvalid==true

maybe this can give you some clue

I looked a bit deeper in code

exception is caused by command
"Delete from KnownEntityTypes where id=@Id; Delete from KnownPropertyTypes where ENTITY_TYPE_ID=@Id; "

(note trailing space at end)

ExecuteNonQuery thinks there are 3 statements and GetStatement produces last third statement with invalid data that causes exception.

If in GetStatement() we replace line
if (String.IsNullOrEmpty(_remainingText) == false) return BuildNextCommand();

with

if (_remainingText !=null && _remainingText.Trim().Length != 0) return BuildNextCommand();

And yahoo! It will work fine :)

Ah -- ok, I'll have it fixed for the next release.  Thanks for tracking it down

Robert