import configparser from .remote import cache_if_remote from collections import namedtuple import os import stat from binascii import unhexlify import shutil from .key import PlaintextKey from .logger import create_logger logger = create_logger() from .helpers import Error, get_cache_dir, decode_dict, int_to_bigint, \ bigint_to_int, format_file_size, yes, bin_to_hex, Location from .locking import Lock from .hashindex import ChunkIndex import msgpack class Cache: """Client Side cache """ class RepositoryIDNotUnique(Error): """Cache is newer than repository - do you have multiple, independently updated repos with same ID?""" class RepositoryReplay(Error): """Cache is newer than repository - this is either an attack or unsafe (multiple repos with same ID)""" class CacheInitAbortedError(Error): """Cache initialization aborted""" class RepositoryAccessAborted(Error): """Repository access aborted""" class EncryptionMethodMismatch(Error): """Repository encryption method changed since last access, refusing to continue""" @staticmethod def break_lock(repository, path=None): path = path or os.path.join(get_cache_dir(), bin_to_hex(repository.id)) Lock(os.path.join(path, 'lock'), exclusive=True).break_lock() @staticmethod def destroy(repository, path=None): """destroy the cache for ``repository`` or at ``path``""" path = path or os.path.join(get_cache_dir(), bin_to_hex(repository.id)) config = os.path.join(path, 'config') if os.path.exists(config): os.remove(config) # kill config first shutil.rmtree(path) def __init__(self, repository, key, manifest, path=None, sync=True, do_files=False, warn_if_unencrypted=True, lock_wait=None): self.lock = None self.timestamp = None self.lock = None self.txn_active = False self.repository = repository self.key = key self.manifest = manifest self.path = path or os.path.join(get_cache_dir(), bin_to_hex(repository.id)) self.do_files = do_files # Warn user before sending data to a never seen before unencrypted repository if not os.path.exists(self.path): if warn_if_unencrypted and isinstance(key, PlaintextKey): msg = ("Warning: Attempting to access a previously unknown unencrypted repository!" + "\n" + "Do you want to continue? [yN] ") if not yes(msg, false_msg="Aborting.", invalid_msg="Invalid answer, aborting.", retry=False, env_var_override='BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK'): raise self.CacheInitAbortedError() self.create() self.open(lock_wait=lock_wait) try: # Warn user before sending data to a relocated repository if self.previous_location and self.previous_location != repository._location.canonical_path(): msg = ("Warning: The repository at location {} was previously located at {}".format(repository._location.canonical_path(), self.previous_location) + "\n" + "Do you want to continue? [yN] ") if not yes(msg, false_msg="Aborting.", invalid_msg="Invalid answer, aborting.", retry=False, env_var_override='BORG_RELOCATED_REPO_ACCESS_IS_OK'): raise self.RepositoryAccessAborted() # adapt on-disk config immediately if the new location was accepted self.begin_txn() self.commit() if sync and self.manifest.id != self.manifest_id: # If repository is older than the cache something fishy is going on if self.timestamp and self.timestamp > manifest.timestamp: if isinstance(key, PlaintextKey): raise self.RepositoryIDNotUnique() else: raise self.RepositoryReplay() # Make sure an encrypted repository has not been swapped for an unencrypted repository if self.key_type is not None and self.key_type != str(key.TYPE): raise self.EncryptionMethodMismatch() self.sync() self.commit() except: self.close() raise def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.close() def __str__(self): fmt = """\ All archives: {0.total_size:>20s} {0.total_csize:>20s} {0.unique_csize:>20s} Unique chunks Total chunks Chunk index: {0.total_unique_chunks:20d} {0.total_chunks:20d}""" return fmt.format(self.format_tuple()) def format_tuple(self): # XXX: this should really be moved down to `hashindex.pyx` Summary = namedtuple('Summary', ['total_size', 'total_csize', 'unique_size', 'unique_csize', 'total_unique_chunks', 'total_chunks']) stats = Summary(*self.chunks.summarize())._asdict() for field in ['total_size', 'total_csize', 'unique_csize']: stats[field] = format_file_size(stats[field]) return Summary(**stats) def create(self): """Create a new empty cache at `self.path` """ os.makedirs(self.path) with open(os.path.join(self.path, 'README'), 'w') as fd: fd.write('This is a Borg cache') config = configparser.ConfigParser(interpolation=None) config.add_section('cache') config.set('cache', 'version', '1') config.set('cache', 'repository', bin_to_hex(self.repository.id)) config.set('cache', 'manifest', '') with open(os.path.join(self.path, 'config'), 'w') as fd: config.write(fd) ChunkIndex().write(os.path.join(self.path, 'chunks').encode('utf-8')) os.makedirs(os.path.join(self.path, 'chunks.archive.d')) with open(os.path.join(self.path, 'files'), 'wb') as fd: pass # empty file def _check_upgrade(self, config_path): try: cache_version = self.config.getint('cache', 'version') wanted_version = 1 if cache_version != wanted_version: self.close() raise Exception('%s has unexpected cache version %d (wanted: %d).' % ( config_path, cache_version, wanted_version)) except configparser.NoSectionError: self.close() raise Exception('%s does not look like a Borg cache.' % config_path) from None # borg < 1.0.8rc1 had different canonicalization for the repo location (see #1655 and #1741). cache_loc = self.config.get('cache', 'previous_location', fallback=None) if cache_loc: repo_loc = self.repository._location.canonical_path() rl = Location(repo_loc) cl = Location(cache_loc) if cl.proto == rl.proto and cl.user == rl.user and cl.host == rl.host and cl.port == rl.port \ and \ cl.path and rl.path and \ cl.path.startswith('/~/') and rl.path.startswith('/./') and cl.path[3:] == rl.path[3:]: # everything is same except the expected change in relative path canonicalization, # update previous_location to avoid warning / user query about changed location: self.config.set('cache', 'previous_location', repo_loc) def _do_open(self): self.config = configparser.ConfigParser(interpolation=None) config_path = os.path.join(self.path, 'config') self.config.read(config_path) self._check_upgrade(config_path) self.id = self.config.get('cache', 'repository') self.manifest_id = unhexlify(self.config.get('cache', 'manifest')) self.timestamp = self.config.get('cache', 'timestamp', fallback=None) self.key_type = self.config.get('cache', 'key_type', fallback=None) self.previous_location = self.config.get('cache', 'previous_location', fallback=None) self.chunks = ChunkIndex.read(os.path.join(self.path, 'chunks').encode('utf-8')) self.files = None def open(self, lock_wait=None): if not os.path.isdir(self.path): raise Exception('%s Does not look like a Borg cache' % self.path) self.lock = Lock(os.path.join(self.path, 'lock'), exclusive=True, timeout=lock_wait).acquire() self.rollback() def close(self): if self.lock is not None: self.lock.release() self.lock = None def _read_files(self): self.files = {} self._newest_mtime = None logger.debug('Reading files cache ...') with open(os.path.join(self.path, 'files'), 'rb') as fd: u = msgpack.Unpacker(use_list=True) while True: data = fd.read(64 * 1024) if not data: break u.feed(data) for path_hash, item in u: item[0] += 1 # in the end, this takes about 240 Bytes per file self.files[path_hash] = msgpack.packb(item) def begin_txn(self): # Initialize transaction snapshot txn_dir = os.path.join(self.path, 'txn.tmp') os.mkdir(txn_dir) shutil.copy(os.path.join(self.path, 'config'), txn_dir) shutil.copy(os.path.join(self.path, 'chunks'), txn_dir) shutil.copy(os.path.join(self.path, 'files'), txn_dir) os.rename(os.path.join(self.path, 'txn.tmp'), os.path.join(self.path, 'txn.active')) self.txn_active = True def commit(self): """Commit transaction """ if not self.txn_active: return if self.files is not None: if self._newest_mtime is None: # was never set because no files were modified/added self._newest_mtime = 2 ** 63 - 1 # nanoseconds, good until y2262 ttl = int(os.environ.get('BORG_FILES_CACHE_TTL', 20)) with open(os.path.join(self.path, 'files'), 'wb') as fd: for path_hash, item in self.files.items(): # Only keep files seen in this backup that are older than newest mtime seen in this backup - # this is to avoid issues with filesystem snapshots and mtime granularity. # Also keep files from older backups that have not reached BORG_FILES_CACHE_TTL yet. item = msgpack.unpackb(item) age = item[0] if age == 0 and bigint_to_int(item[3]) < self._newest_mtime or \ age > 0 and age < ttl: msgpack.pack((path_hash, item), fd) self.config.set('cache', 'manifest', bin_to_hex(self.manifest.id)) self.config.set('cache', 'timestamp', self.manifest.timestamp) self.config.set('cache', 'key_type', str(self.key.TYPE)) self.config.set('cache', 'previous_location', self.repository._location.canonical_path()) with open(os.path.join(self.path, 'config'), 'w') as fd: self.config.write(fd) self.chunks.write(os.path.join(self.path, 'chunks').encode('utf-8')) os.rename(os.path.join(self.path, 'txn.active'), os.path.join(self.path, 'txn.tmp')) shutil.rmtree(os.path.join(self.path, 'txn.tmp')) self.txn_active = False def rollback(self): """Roll back partial and aborted transactions """ # Remove partial transaction if os.path.exists(os.path.join(self.path, 'txn.tmp')): shutil.rmtree(os.path.join(self.path, 'txn.tmp')) # Roll back active transaction txn_dir = os.path.join(self.path, 'txn.active') if os.path.exists(txn_dir): shutil.copy(os.path.join(txn_dir, 'config'), self.path) shutil.copy(os.path.join(txn_dir, 'chunks'), self.path) shutil.copy(os.path.join(txn_dir, 'files'), self.path) os.rename(txn_dir, os.path.join(self.path, 'txn.tmp')) if os.path.exists(os.path.join(self.path, 'txn.tmp')): shutil.rmtree(os.path.join(self.path, 'txn.tmp')) self.txn_active = False self._do_open() def sync(self): """Re-synchronize chunks cache with repository. Maintains a directory with known backup archive indexes, so it only needs to fetch infos from repo and build a chunk index once per backup archive. If out of sync, missing archive indexes get added, outdated indexes get removed and a new master chunks index is built by merging all archive indexes. """ archive_path = os.path.join(self.path, 'chunks.archive.d') def mkpath(id, suffix=''): id_hex = bin_to_hex(id) path = os.path.join(archive_path, id_hex + suffix) return path.encode('utf-8') def cached_archives(): if self.do_cache: fns = os.listdir(archive_path) # filenames with 64 hex digits == 256bit return set(unhexlify(fn) for fn in fns if len(fn) == 64) else: return set() def repo_archives(): return set(info[b'id'] for info in self.manifest.archives.values()) def cleanup_outdated(ids): for id in ids: os.unlink(mkpath(id)) def fetch_and_build_idx(archive_id, repository, key): chunk_idx = ChunkIndex() cdata = repository.get(archive_id) data = key.decrypt(archive_id, cdata) chunk_idx.add(archive_id, 1, len(data), len(cdata)) archive = msgpack.unpackb(data) if archive[b'version'] != 1: raise Exception('Unknown archive metadata version') decode_dict(archive, (b'name',)) unpacker = msgpack.Unpacker() for item_id, chunk in zip(archive[b'items'], repository.get_many(archive[b'items'])): data = key.decrypt(item_id, chunk) chunk_idx.add(item_id, 1, len(data), len(chunk)) unpacker.feed(data) for item in unpacker: if not isinstance(item, dict): logger.error('Error: Did not get expected metadata dict - archive corrupted!') continue if b'chunks' in item: for chunk_id, size, csize in item[b'chunks']: chunk_idx.add(chunk_id, 1, size, csize) if self.do_cache: fn = mkpath(archive_id) fn_tmp = mkpath(archive_id, suffix='.tmp') try: chunk_idx.write(fn_tmp) except Exception: os.unlink(fn_tmp) else: os.rename(fn_tmp, fn) return chunk_idx def lookup_name(archive_id): for name, info in self.manifest.archives.items(): if info[b'id'] == archive_id: return name def create_master_idx(chunk_idx): logger.info('Synchronizing chunks cache...') cached_ids = cached_archives() archive_ids = repo_archives() logger.info('Archives: %d, w/ cached Idx: %d, w/ outdated Idx: %d, w/o cached Idx: %d.' % ( len(archive_ids), len(cached_ids), len(cached_ids - archive_ids), len(archive_ids - cached_ids), )) # deallocates old hashindex, creates empty hashindex: chunk_idx.clear() cleanup_outdated(cached_ids - archive_ids) if archive_ids: chunk_idx = None for archive_id in archive_ids: archive_name = lookup_name(archive_id) if archive_id in cached_ids: archive_chunk_idx_path = mkpath(archive_id) logger.info("Reading cached archive chunk index for %s ..." % archive_name) archive_chunk_idx = ChunkIndex.read(archive_chunk_idx_path) else: logger.info('Fetching and building archive index for %s ...' % archive_name) archive_chunk_idx = fetch_and_build_idx(archive_id, repository, self.key) logger.info("Merging into master chunks index ...") if chunk_idx is None: # we just use the first archive's idx as starting point, # to avoid growing the hash table from 0 size and also # to save 1 merge call. chunk_idx = archive_chunk_idx else: chunk_idx.merge(archive_chunk_idx) logger.info('Done.') return chunk_idx def legacy_cleanup(): """bring old cache dirs into the desired state (cleanup and adapt)""" try: os.unlink(os.path.join(self.path, 'chunks.archive')) except: pass try: os.unlink(os.path.join(self.path, 'chunks.archive.tmp')) except: pass try: os.mkdir(archive_path) except: pass self.begin_txn() with cache_if_remote(self.repository) as repository: legacy_cleanup() # TEMPORARY HACK: to avoid archive index caching, create a FILE named ~/.cache/borg/REPOID/chunks.archive.d - # this is only recommended if you have a fast, low latency connection to your repo (e.g. if repo is local disk) self.do_cache = os.path.isdir(archive_path) self.chunks = create_master_idx(self.chunks) def add_chunk(self, id, data, stats): if not self.txn_active: self.begin_txn() size = len(data) if self.seen_chunk(id, size): return self.chunk_incref(id, stats) data = self.key.encrypt(data) csize = len(data) self.repository.put(id, data, wait=False) self.chunks[id] = (1, size, csize) stats.update(size, csize, True) return id, size, csize def seen_chunk(self, id, size=None): refcount, stored_size, _ = self.chunks.get(id, (0, None, None)) if size is not None and stored_size is not None and size != stored_size: # we already have a chunk with that id, but different size. # this is either a hash collision (unlikely) or corruption or a bug. raise Exception("chunk has same id [%r], but different size (stored: %d new: %d)!" % ( id, stored_size, size)) return refcount def chunk_incref(self, id, stats): if not self.txn_active: self.begin_txn() count, size, csize = self.chunks.incref(id) stats.update(size, csize, False) return id, size, csize def chunk_decref(self, id, stats): if not self.txn_active: self.begin_txn() count, size, csize = self.chunks.decref(id) if count == 0: del self.chunks[id] self.repository.delete(id, wait=False) stats.update(-size, -csize, True) else: stats.update(-size, -csize, False) def file_known_and_unchanged(self, path_hash, st, ignore_inode=False): if not (self.do_files and stat.S_ISREG(st.st_mode)): return None if self.files is None: self._read_files() entry = self.files.get(path_hash) if not entry: return None entry = msgpack.unpackb(entry) if (entry[2] == st.st_size and bigint_to_int(entry[3]) == st.st_mtime_ns and (ignore_inode or entry[1] == st.st_ino)): # reset entry age entry[0] = 0 self.files[path_hash] = msgpack.packb(entry) return entry[4] else: return None def memorize_file(self, path_hash, st, ids): if not (self.do_files and stat.S_ISREG(st.st_mode)): return # Entry: Age, inode, size, mtime, chunk ids mtime_ns = st.st_mtime_ns self.files[path_hash] = msgpack.packb((0, st.st_ino, st.st_size, int_to_bigint(mtime_ns), ids)) self._newest_mtime = max(self._newest_mtime or 0, mtime_ns)