ScpLocalFile.finish

bool finish(ScpMetadataPolicy policy,  uint  mode,  ulong  mtimeSeconds,
          ulong  atimeSeconds,  ref  string errorMessage)

Applies caller-authorized metadata and closes the file.

`policy`	Metadata authorization flags.
`mode`	Permission bits from the header (masked to 07777).
`mtimeSeconds`	Modification time from the timestamp record.
`atimeSeconds`	Access time from the timestamp record.
`errorMessage`	Receives the failure description.

true when metadata application and close succeeded.