def write_good_share(storage_rref, storage_index, ueb, sharenums):
"""
Write a valid share with the given URI extension block.
"""
write_proxy = make_write_bucket_proxy(
storage_rref,
None,
1024,
ueb["segment_size"],
1,
1,
ueb["size"],
)
# See allmydata/immutable/layout.py
offset = write_proxy._offsets["uri_extension"]
filler = b"\0" * (offset - len(write_proxy._offset_data))
ueb_data = uri.pack_extension(ueb)
data = (write_proxy._offset_data + filler +
pack(write_proxy.fieldstruct, len(ueb_data)) + ueb_data)
return write_share(storage_rref, storage_index, sharenums, data)
def _guess_offsets(self, verifycap, guessed_segment_size):
self.guessed_segment_size = guessed_segment_size
size = verifycap.size
k = verifycap.needed_shares
N = verifycap.total_shares
r = self._node._calculate_sizes(guessed_segment_size)
# num_segments, block_size/tail_block_size
# guessed_segment_size/tail_segment_size/tail_segment_padded
share_size = mathutil.div_ceil(size, k)
# share_size is the amount of block data that will be put into each
# share, summed over all segments. It does not include hashes, the
# UEB, or other overhead.
# use the upload-side code to get this as accurate as possible
ht = IncompleteHashTree(N)
num_share_hashes = len(ht.needed_hashes(0, include_leaf=True))
wbp = make_write_bucket_proxy(None, None, share_size, r["block_size"],
r["num_segments"], num_share_hashes, 0)
self._fieldsize = wbp.fieldsize
self._fieldstruct = wbp.fieldstruct
self.guessed_offsets = wbp._offsets