def Read(self, path, length=None, offset=0, fh=None):
fd = aff4.FACTORY.Open(self.root.Add(path), token=self.token)
last = fd.Get(fd.Schema.CONTENT_LAST)
client_id = rdf_client.GetClientURNFromPath(path)
if not self.DataRefreshRequired(last=last, path=path):
return super(GRRFuse, self).Read(path, length, offset, fh)
if isinstance(fd, standard.AFF4SparseImage):
# If we have a sparse image, update just a part of it.
self.UpdateSparseImageIfNeeded(fd, length, offset)
# Read the file from the datastore as usual.
return super(GRRFuse, self).Read(path, length, offset, fh)
# If it's the first time we've seen this path (or we're asking
# explicitly), try and make it an AFF4SparseImage.
if last is None or self.force_sparse_image:
pathspec = fd.Get(fd.Schema.PATHSPEC)
# Either makes a new AFF4SparseImage or gets the file fully,
# depending on size.
flow_utils.StartFlowAndWait(
client_id,
token=self.token,
flow_name=filesystem.MakeNewAFF4SparseImage.__name__,
pathspec=pathspec,
size_threshold=self.size_threshold)
# Reopen the fd in case it's changed to be an AFF4SparseImage
fd = aff4.FACTORY.Open(self.root.Add(path), token=self.token)
# If we are now a sparse image, just download the part we requested
# from the client.
if isinstance(fd, standard.AFF4SparseImage):
flow_utils.StartFlowAndWait(
client_id,
token=self.token,
flow_name=filesystem.FetchBufferForSparseImage.__name__,
file_urn=self.root.Add(path),
length=length,
offset=offset)
else:
# This was a file we'd seen before that wasn't a sparse image, so update
# it the usual way.
self._RunAndWaitForVFSFileUpdate(path)
# Read the file from the datastore as usual.
return super(GRRFuse, self).Read(path, length, offset, fh)
def UpdateSparseImageIfNeeded(self, fd, length, offset):
missing_chunks = self.GetMissingChunks(fd, length, offset)
if not missing_chunks:
return
client_id = rdf_client.GetClientURNFromPath(fd.urn.Path())
flow_utils.StartFlowAndWait(
client_id,
token=self.token,
flow_name=filesystem.UpdateSparseImageChunks.__name__,
file_urn=fd.urn,
chunks_to_fetch=missing_chunks)