MORK_USED_1(ioHeap);
morkStream::AcquireBud(morkEnv* ev, nsIMdbHeap* ioHeap)  // AcquireBud() starts a new "branch" version of the file, empty of content,  // so that a new version of the file can be written.  This new file  // can later be told to BecomeTrunk() the original file, so the branch  // created by budding the file will replace the original file.  Some  // file subclasses might initially take the unsafe but expedient  // approach of simply truncating this file down to zero length, and  // then returning the same morkFile pointer as this, with an extra  // reference count increment.  Note that the caller of AcquireBud() is  // expected to eventually call CutStrongRef() on the returned file  // in order to release the strong reference.  High quality versions  // of morkFile subclasses will create entirely new files which later  // are renamed to become the old file, so that better transactional  // behavior is exhibited by the file, so crashes protect old files.  // Note that AcquireBud() is an illegal operation on readonly files.{  MORK_USED_1(ioHeap);  morkFile* outFile = 0;  morkFile* file = mStream_ContentFile;  if ( this->IsOpenAndActiveFile() && file )  {    // figure out how this interacts with buffering and mStream_WriteEnd:    ev->StubMethodOnlyError();  }  else this->NewFileDownError(ev);    return outFile;}