VaultRead Event

Fires to read data from a callback mode vault.

Syntax

• C#
• VB.NET

public event OnVaultReadHandler OnVaultRead;

public delegate void OnVaultReadHandler(object sender, CbdriveVaultReadEventArgs e);

public class CbdriveVaultReadEventArgs : EventArgs {
  public long VaultHandle { get; }
  public long Offset { get; }
  public IntPtr Buffer { get; }
  public int Count { get; }
  public int ResultCode { get; set; }
}

Public Event OnVaultRead As OnVaultReadHandler

Public Delegate Sub OnVaultReadHandler(sender As Object, e As CbdriveVaultReadEventArgs)

Public Class CbdriveVaultReadEventArgs Inherits EventArgs
  Public ReadOnly Property VaultHandle As Long
  Public ReadOnly Property Offset As Long
  Public ReadOnly Property Buffer As IntPtr
  Public ReadOnly Property Count As Integer
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the component needs to read data from the callback mode vault specified by VaultHandle.

This event only needs to be handled if the CallbackMode property is enabled; please refer to the Callback Mode topic for more information. To handle this event properly, applications must read Count bytes of data from the vault specified by VaultHandle into Buffer, starting at the specified Offset in the vault.

Count is always a multiple of the vault's PageSize. If, for any reason, an application cannot read exactly Count bytes of data from the vault, it must return an appropriate error code via ResultCode.

Please refer to the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The VaultHandle parameter contains an application-defined handle to an open callback mode vault, as returned by the application in an earlier VaultOpen event.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.

Note: An application should not attempt to call component's methods from handlers of this event. Doing this is guaranteed to cause a deadlock.

Note: when a storage is opened concurrently in read-only mode by several applications using CBDrive or CBMemDrive component, the event will fire only in the first application. To prevent such a situation, always open a vault in read-write mode.