Fires before information about a file or directory is changed.
type TBeforeSetFileInfoEvent = procedure ( Sender: TObject; const FileName: String; FileInformationClass: Integer; Buffer: Pointer; BufferLength: Integer; var ValidBytes: Integer; var FileContext: Pointer; var HandleContext: Pointer; var ProcessRequest: Boolean; var ResultCode: Integer ) of Object;
property OnBeforeSetFileInfo: TBeforeSetFileInfoEvent read FOnBeforeSetFileInfo write FOnBeforeSetFileInfo;
This event fires before information about the file or directory specified by FileName is changed; typically in response to the Windows API's NtSetInformationFile function.
Applications may use this event to modify the request's data before it continues onward, in which case they 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.
Alternatively, applications may use this event to handle the underlying request, preventing it from continuing onwards, by setting ProcessRequest to False.
The FileInformationClass parameter indicates what kind of file information is to be changed. Please refer to the NtSetInformationFile function's documentation for more information about possible values.
The Buffer parameter points to a memory buffer that specifies the new 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 NtSetInformationFile function's documentation for more information.
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 ProcessRequest parameter controls whether the request is sent onwards for further processing by subsequent filter drivers and the filesystem; it is True by default.
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.