Fires after information about a file or directory is retrieved.
type TAfterQueryFileInfoEvent = procedure ( Sender: TObject; const FileName: String; FileInformationClass: Integer; Buffer: Pointer; BufferLength: Integer; var ValidBytes: Integer; var Status: Integer; var FileContext: Pointer; var HandleContext: Pointer; var ResultCode: Integer ) of Object;
property OnAfterQueryFileInfo: TAfterQueryFileInfoEvent read FOnAfterQueryFileInfo write FOnAfterQueryFileInfo;
This event fires after information about the file or directory specified by FileName is retrieved; typically in response to the Windows API's NtQueryInformationFile function.
Applications may use this event to modify the output data before the response is returned to the requestor. Applications that choose to do this must:
- Copy no more than BufferLength bytes into Buffer.
- Update the ValidBytes parameter's value afterwards so that it correctly reflects the amount of data in Buffer.
The FileInformationClass parameter indicates what kind of file information was requested. Please refer to the NtQueryInformationFile function's documentation for more information about possible values.
The Buffer parameter points to a memory buffer that, if the request was successful, contains the requested file information. The BufferLength and ValidBytes parameters reflect the capacity of Buffer and the length of the data it contains (respectively), in bytes; ValidBytes may be less than BufferLength. Please refer to the Buffer Parameters topic for more information on how to work with memory buffer event parameters.
The format of the data itself is determined by the specified FileInformationClass; please refer to the NtQueryInformationFile function's documentation for more information.
The Status parameter contains an NT status code that indicates the outcome of the operation; 0 indicates success. To convert this value to a Win32 error code, call the NtStatusToWin32Error method. Please note that this event won't fire for failed requests unless the ProcessFailedRequests property is enabled. Applications may change this parameter's value if they want a different NT status code to be returned.
The FileContext and HandleContext parameters are placeholders for application-defined data associated with the file and specific handle, respectively. Please refer to the Contexts topic for more information.
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.
This event is fired synchronously; please refer to the Event Types topic for more information.