NTSTATUS
RtlAbsoluteToSelfRelativeSD(
  IN  PSECURITY_DESCRIPTOR AbsoluteSecurityDescriptor,
  IN OUT PSECURITY_DESCRIPTOR SelfRelativeSecurityDescriptor,
  IN OUT PULONG BufferLength
  );

Routine Description:

    Converts a security descriptor in absolute form to one in self-relative
    form.

Arguments:

    AbsoluteSecurityDescriptor - Pointer to an absolute format security
        descriptor.  This descriptor will not be modified.

    SelfRelativeSecurityDescriptor - Pointer to a buffer that will contain
        the returned self-relative security descriptor.

    BufferLength - Supplies the length of the buffer.  If the supplied
        buffer is not large enough to hold the self-relative security
        descriptor, an error will be returned, and this field will return
        the minimum size required.


Return Value:

    STATUS_BUFFER_TOO_SMALL - The supplied buffer was too small to contain
        the resultant security descriptor.

    STATUS_BAD_DESCRIPTOR_FORMAT - The supplied security descriptor was not
        in absolute form.