Protect virtual dataset filename translation better

h5py/_hl/vds.py

@@ -169,19 +169,19 @@ def __init__(self, shape, dtype, maxshape=None, filename=None):
  self.shape = (shape,) if isinstance(shape, int) else shape
  self.dtype = dtype
  self.maxshape = (maxshape,) if isinstance(maxshape, int) else maxshape
- self.filename = filename
+ self._filename = filename
  self._src_filenames = set()
  self.dcpl = h5p.create(h5p.DATASET_CREATE)
 
  def __setitem__(self, key, source):
  sel = select(self.shape, key, dataset=None)
  _convert_space_for_key(sel.id, key)
- src_filename = self._source_file_name(source.path, self.filename)
+ src_filename = self._source_file_name(source.path, self._filename)
 
  self.dcpl.set_virtual(
  sel.id, src_filename, source.name.encode('utf-8'), source.sel.id
  )
- if self.filename is None:
+ if self._filename is None:
  self._src_filenames.add(src_filename)
 
  @staticmethod
@@ -194,14 +194,21 @@ def _source_file_name(src_filename, dst_filename) -> bytes:
  return b'.'
  return filename_encode(src_filename)
 
- def get_dcpl(self, dst_filename):
+ def _get_dcpl(self, dst_filename):
  """Get the property list containing virtual dataset mappings
 
  If the destination filename wasn't known when the VirtualLayout was
  created, it is handled here.
  """
  dst_filename = filename_encode(dst_filename)
- if (self.filename is None) and (dst_filename in self._src_filenames):
+ if self._filename is not None:
+ # filename was known in advance; check dst_filename matches
+ if dst_filename != filename_encode(self._filename):
+ raise Exception(f"{dst_filename!r} != {self._filename!r}")
+ return self.dcpl
+
+ # destination file not known in advance
+ if dst_filename in self._src_filenames:
  # At least 1 source file is the same as the destination file,
  # but we didn't know this when making the mapping. Copy the mappings
  # to a new property list, replacing the dest filename with '.'
@@ -216,11 +223,11 @@ def get_dcpl(self, dst_filename):
  )
  return new_dcpl
  else:
- return self.dcpl
+ return self.dcpl # Mappings are all from other files
 
  def make_dataset(self, parent, name, fillvalue=None):
  """ Return a new low-level dataset identifier for a virtual dataset """
- dcpl = self.get_dcpl(parent.file.filename)
+ dcpl = self._get_dcpl(parent.file.filename)
 
  if fillvalue is not None:
  dcpl.set_fill_value(np.array([fillvalue]))