--- a/mercurial/revlogutils/censor.py Thu Jun 17 19:48:25 2021 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,359 +0,0 @@
-# censor code related to censoring revision
-# coding: utf8
-#
-# Copyright 2021 Pierre-Yves David <pierre-yves.david@octobus.net>
-# Copyright 2015 Google, Inc <martinvonz@google.com>
-#
-# This software may be used and distributed according to the terms of the
-# GNU General Public License version 2 or any later version.
-
-import contextlib
-import os
-
-from ..node import (
- nullrev,
-)
-from .constants import (
- COMP_MODE_PLAIN,
- ENTRY_DATA_COMPRESSED_LENGTH,
- ENTRY_DATA_COMPRESSION_MODE,
- ENTRY_DATA_OFFSET,
- ENTRY_DATA_UNCOMPRESSED_LENGTH,
- ENTRY_DELTA_BASE,
- ENTRY_LINK_REV,
- ENTRY_NODE_ID,
- ENTRY_PARENT_1,
- ENTRY_PARENT_2,
- ENTRY_SIDEDATA_COMPRESSED_LENGTH,
- ENTRY_SIDEDATA_COMPRESSION_MODE,
- ENTRY_SIDEDATA_OFFSET,
- REVLOGV0,
- REVLOGV1,
-)
-from ..i18n import _
-
-from .. import (
- error,
- pycompat,
- revlogutils,
- util,
-)
-from ..utils import (
- storageutil,
-)
-from . import (
- constants,
- deltas,
-)
-
-
-def v1_censor(rl, tr, censornode, tombstone=b''):
- """censors a revision in a "version 1" revlog"""
- assert rl._format_version == constants.REVLOGV1, rl._format_version
-
- # avoid cycle
- from .. import revlog
-
- censorrev = rl.rev(censornode)
- tombstone = storageutil.packmeta({b'censored': tombstone}, b'')
-
- # Rewriting the revlog in place is hard. Our strategy for censoring is
- # to create a new revlog, copy all revisions to it, then replace the
- # revlogs on transaction close.
- #
- # This is a bit dangerous. We could easily have a mismatch of state.
- newrl = revlog.revlog(
- rl.opener,
- target=rl.target,
- radix=rl.radix,
- postfix=b'tmpcensored',
- censorable=True,
- )
- newrl._format_version = rl._format_version
- newrl._format_flags = rl._format_flags
- newrl._generaldelta = rl._generaldelta
- newrl._parse_index = rl._parse_index
-
- for rev in rl.revs():
- node = rl.node(rev)
- p1, p2 = rl.parents(node)
-
- if rev == censorrev:
- newrl.addrawrevision(
- tombstone,
- tr,
- rl.linkrev(censorrev),
- p1,
- p2,
- censornode,
- constants.REVIDX_ISCENSORED,
- )
-
- if newrl.deltaparent(rev) != nullrev:
- m = _(b'censored revision stored as delta; cannot censor')
- h = _(
- b'censoring of revlogs is not fully implemented;'
- b' please report this bug'
- )
- raise error.Abort(m, hint=h)
- continue
-
- if rl.iscensored(rev):
- if rl.deltaparent(rev) != nullrev:
- m = _(
- b'cannot censor due to censored '
- b'revision having delta stored'
- )
- raise error.Abort(m)
- rawtext = rl._chunk(rev)
- else:
- rawtext = rl.rawdata(rev)
-
- newrl.addrawrevision(
- rawtext, tr, rl.linkrev(rev), p1, p2, node, rl.flags(rev)
- )
-
- tr.addbackup(rl._indexfile, location=b'store')
- if not rl._inline:
- tr.addbackup(rl._datafile, location=b'store')
-
- rl.opener.rename(newrl._indexfile, rl._indexfile)
- if not rl._inline:
- rl.opener.rename(newrl._datafile, rl._datafile)
-
- rl.clearcaches()
- rl._loadindex()
-
-
-def v2_censor(rl, tr, censornode, tombstone=b''):
- """censors a revision in a "version 2" revlog"""
- # General principle
- #
- # We create new revlog files (index/data/sidedata) to copy the content of
- # the existing data without the censored data.
- #
- # We need to recompute new delta for any revision that used the censored
- # revision as delta base. As the cumulative size of the new delta may be
- # large, we store them in a temporary file until they are stored in their
- # final destination.
- #
- # All data before the censored data can be blindly copied. The rest needs
- # to be copied as we go and the associated index entry needs adjustement.
-
- assert rl._format_version != REVLOGV0, rl._format_version
- assert rl._format_version != REVLOGV1, rl._format_version
-
- old_index = rl.index
- docket = rl._docket
-
- censor_rev = rl.rev(censornode)
- tombstone = storageutil.packmeta({b'censored': tombstone}, b'')
-
- censored_entry = rl.index[censor_rev]
- index_cutoff = rl.index.entry_size * censor_rev
- data_cutoff = censored_entry[ENTRY_DATA_OFFSET] >> 16
- sidedata_cutoff = rl.sidedata_cut_off(censor_rev)
-
- # rev → (new_base, data_start, data_end)
- rewritten_entries = {}
-
- dc = deltas.deltacomputer(rl)
- excl = [censor_rev]
-
- with pycompat.unnamedtempfile(mode=b"w+b") as tmp_storage:
- with rl._segmentfile._open_read() as dfh:
- for rev in range(censor_rev + 1, len(old_index)):
- entry = old_index[rev]
- if censor_rev != entry[ENTRY_DELTA_BASE]:
- continue
- # This is a revision that use the censored revision as the base
- # for its delta. We need a need new deltas
- if entry[ENTRY_DATA_UNCOMPRESSED_LENGTH] == 0:
- # this revision is empty, we can delta against nullrev
- rewritten_entries[rev] = (nullrev, 0, 0)
- else:
-
- text = rl.rawdata(rev, _df=dfh)
- info = revlogutils.revisioninfo(
- node=entry[ENTRY_NODE_ID],
- p1=rl.node(entry[ENTRY_PARENT_1]),
- p2=rl.node(entry[ENTRY_PARENT_2]),
- btext=[text],
- textlen=len(text),
- cachedelta=None,
- flags=entry[ENTRY_DATA_OFFSET] & 0xFFFF,
- )
- d = dc.finddeltainfo(
- info, dfh, excluded_bases=excl, target_rev=rev
- )
- default_comp = rl._docket.default_compression_header
- comp_mode, d = deltas.delta_compression(default_comp, d)
- # using `tell` is a bit lazy, but we are not here for speed
- start = tmp_storage.tell()
- tmp_storage.write(d.data[1])
- end = tmp_storage.tell()
- rewritten_entries[rev] = (d.base, start, end, comp_mode)
-
- old_index_filepath = rl.opener.join(docket.index_filepath())
- old_data_filepath = rl.opener.join(docket.data_filepath())
- old_sidedata_filepath = rl.opener.join(docket.sidedata_filepath())
-
- new_index_filepath = rl.opener.join(docket.new_index_file())
- new_data_filepath = rl.opener.join(docket.new_data_file())
- new_sidedata_filepath = rl.opener.join(docket.new_sidedata_file())
-
- util.copyfile(
- old_index_filepath, new_index_filepath, nb_bytes=index_cutoff
- )
- util.copyfile(
- old_data_filepath, new_data_filepath, nb_bytes=data_cutoff
- )
- util.copyfile(
- old_sidedata_filepath,
- new_sidedata_filepath,
- nb_bytes=sidedata_cutoff,
- )
- rl.opener.register_file(docket.index_filepath())
- rl.opener.register_file(docket.data_filepath())
- rl.opener.register_file(docket.sidedata_filepath())
-
- docket.index_end = index_cutoff
- docket.data_end = data_cutoff
- docket.sidedata_end = sidedata_cutoff
-
- # reload the revlog internal information
- rl.clearcaches()
- rl._loadindex(docket=docket)
-
- @contextlib.contextmanager
- def all_files():
- # hide opening in an helper function to please check-code, black
- # and various python ersion at the same time
- with open(old_data_filepath, 'rb') as old_data_file:
- with open(old_sidedata_filepath, 'rb') as old_sidedata_file:
- with open(new_index_filepath, 'r+b') as new_index_file:
- with open(new_data_filepath, 'r+b') as new_data_file:
- with open(
- new_sidedata_filepath, 'r+b'
- ) as new_sidedata_file:
- yield (
- old_data_file,
- old_sidedata_file,
- new_index_file,
- new_data_file,
- new_sidedata_file,
- )
-
- # we dont need to open the old index file since its content already
- # exist in a usable form in `old_index`.
- with all_files() as (
- old_data_file,
- old_sidedata_file,
- new_index_file,
- new_data_file,
- new_sidedata_file,
- ):
- new_index_file.seek(0, os.SEEK_END)
- assert new_index_file.tell() == index_cutoff
- new_data_file.seek(0, os.SEEK_END)
- assert new_data_file.tell() == data_cutoff
- new_sidedata_file.seek(0, os.SEEK_END)
- assert new_sidedata_file.tell() == sidedata_cutoff
-
- ### writing the censored revision
- entry = old_index[censor_rev]
-
- # XXX consider trying the default compression too
- new_data_size = len(tombstone)
- new_data_offset = new_data_file.tell()
- new_data_file.write(tombstone)
-
- # we are not adding any sidedata as they might leak info about the censored version
-
- new_entry = revlogutils.entry(
- flags=constants.REVIDX_ISCENSORED,
- data_offset=new_data_offset,
- data_compressed_length=new_data_size,
- data_uncompressed_length=new_data_size,
- data_delta_base=censor_rev,
- link_rev=entry[ENTRY_LINK_REV],
- parent_rev_1=entry[ENTRY_PARENT_1],
- parent_rev_2=entry[ENTRY_PARENT_2],
- node_id=entry[ENTRY_NODE_ID],
- sidedata_offset=0,
- sidedata_compressed_length=0,
- data_compression_mode=COMP_MODE_PLAIN,
- sidedata_compression_mode=COMP_MODE_PLAIN,
- )
- rl.index.append(new_entry)
- entry_bin = rl.index.entry_binary(censor_rev)
- new_index_file.write(entry_bin)
- docket.index_end = new_index_file.tell()
- docket.data_end = new_data_file.tell()
-
- #### Writing all subsequent revisions
- for rev in range(censor_rev + 1, len(old_index)):
- entry = old_index[rev]
- flags = entry[ENTRY_DATA_OFFSET] & 0xFFFF
- old_data_offset = entry[ENTRY_DATA_OFFSET] >> 16
-
- if rev not in rewritten_entries:
- old_data_file.seek(old_data_offset)
- new_data_size = entry[ENTRY_DATA_COMPRESSED_LENGTH]
- new_data = old_data_file.read(new_data_size)
- data_delta_base = entry[ENTRY_DELTA_BASE]
- d_comp_mode = entry[ENTRY_DATA_COMPRESSION_MODE]
- else:
- (
- data_delta_base,
- start,
- end,
- d_comp_mode,
- ) = rewritten_entries[rev]
- new_data_size = end - start
- tmp_storage.seek(start)
- new_data = tmp_storage.read(new_data_size)
-
- # It might be faster to group continuous read/write operation,
- # however, this is censor, an operation that is not focussed
- # around stellar performance. So I have not written this
- # optimisation yet.
- new_data_offset = new_data_file.tell()
- new_data_file.write(new_data)
-
- sidedata_size = entry[ENTRY_SIDEDATA_COMPRESSED_LENGTH]
- new_sidedata_offset = new_sidedata_file.tell()
- if 0 < sidedata_size:
- old_sidedata_offset = entry[ENTRY_SIDEDATA_OFFSET]
- old_sidedata_file.seek(old_sidedata_offset)
- new_sidedata = old_sidedata_file.read(sidedata_size)
- new_sidedata_file.write(new_sidedata)
-
- data_uncompressed_length = entry[ENTRY_DATA_UNCOMPRESSED_LENGTH]
- sd_com_mode = entry[ENTRY_SIDEDATA_COMPRESSION_MODE]
- assert data_delta_base <= rev, (data_delta_base, rev)
-
- new_entry = revlogutils.entry(
- flags=flags,
- data_offset=new_data_offset,
- data_compressed_length=new_data_size,
- data_uncompressed_length=data_uncompressed_length,
- data_delta_base=data_delta_base,
- link_rev=entry[ENTRY_LINK_REV],
- parent_rev_1=entry[ENTRY_PARENT_1],
- parent_rev_2=entry[ENTRY_PARENT_2],
- node_id=entry[ENTRY_NODE_ID],
- sidedata_offset=new_sidedata_offset,
- sidedata_compressed_length=sidedata_size,
- data_compression_mode=d_comp_mode,
- sidedata_compression_mode=sd_com_mode,
- )
- rl.index.append(new_entry)
- entry_bin = rl.index.entry_binary(rev)
- new_index_file.write(entry_bin)
-
- docket.index_end = new_index_file.tell()
- docket.data_end = new_data_file.tell()
- docket.sidedata_end = new_sidedata_file.tell()
-
- docket.write(transaction=None, stripping=True)