attic/archive.py
from datetime import datetime
from getpass import getuser
from itertools import groupby
import errno
import shutil
import tempfile
from attic.key import key_factory
from attic.remote import cache_if_remote
import msgpack
import os
import socket
import stat
import sys
import time
from io import BytesIO
from attic import xattr
from attic.platform import acl_get, acl_set
from attic.chunker import Chunker
from attic.hashindex import ChunkIndex
from attic.helpers import parse_timestamp, Error, uid2user, user2uid, gid2group, group2gid, \
Manifest, Statistics, decode_dict, st_mtime_ns, make_path_safe, StableDict, int_to_bigint, bigint_to_int
ITEMS_BUFFER = 1024 * 1024
CHUNK_MIN = 1024
WINDOW_SIZE = 0xfff
CHUNK_MASK = 0xffff
utime_supports_fd = os.utime in getattr(os, 'supports_fd', {})
utime_supports_follow_symlinks = os.utime in getattr(os, 'supports_follow_symlinks', {})
has_mtime_ns = sys.version >= '3.3'
has_lchmod = hasattr(os, 'lchmod')
has_lchflags = hasattr(os, 'lchflags')
# Python <= 3.2 raises OSError instead of PermissionError (See #164)
try:
PermissionError = PermissionError
except NameError:
PermissionError = OSError
class DownloadPipeline:
def __init__(self, repository, key):
self.repository = repository
self.key = key
def unpack_many(self, ids, filter=None, preload=False):
unpacker = msgpack.Unpacker(use_list=False)
for data in self.fetch_many(ids):
unpacker.feed(data)
items = [decode_dict(item, (b'path', b'source', b'user', b'group')) for item in unpacker]
if filter:
items = [item for item in items if filter(item)]
if preload:
for item in items:
if b'chunks' in item:
self.repository.preload([c[0] for c in item[b'chunks']])
for item in items:
yield item
def fetch_many(self, ids, is_preloaded=False):
for id_, data in zip(ids, self.repository.get_many(ids, is_preloaded=is_preloaded)):
yield self.key.decrypt(id_, data)
class ChunkBuffer:
BUFFER_SIZE = 1 * 1024 * 1024
def __init__(self, key):
self.buffer = BytesIO()
self.packer = msgpack.Packer(unicode_errors='surrogateescape')
self.chunks = []
self.key = key
self.chunker = Chunker(WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, self.key.chunk_seed)
def add(self, item):
self.buffer.write(self.packer.pack(StableDict(item)))
if self.is_full():
self.flush()
def write_chunk(self, chunk):
raise NotImplementedError
def flush(self, flush=False):
if self.buffer.tell() == 0:
return
self.buffer.seek(0)
chunks = list(bytes(s) for s in self.chunker.chunkify(self.buffer))
self.buffer.seek(0)
self.buffer.truncate(0)
# Leave the last partial chunk in the buffer unless flush is True
end = None if flush or len(chunks) == 1 else -1
for chunk in chunks[:end]:
self.chunks.append(self.write_chunk(chunk))
if end == -1:
self.buffer.write(chunks[-1])
def is_full(self):
return self.buffer.tell() > self.BUFFER_SIZE
class CacheChunkBuffer(ChunkBuffer):
def __init__(self, cache, key, stats):
super(CacheChunkBuffer, self).__init__(key)
self.cache = cache
self.stats = stats
def write_chunk(self, chunk):
id_, _, _ = self.cache.add_chunk(self.key.id_hash(chunk), chunk, self.stats)
return id_
class Archive:
class DoesNotExist(Error):
"""Archive {} does not exist"""
class AlreadyExists(Error):
"""Archive {} already exists"""
class IncompatibleFilesystemEncodingError(Error):
"""Failed to encode filename "{}" into file system encoding "{}". Consider configuring the LANG environment variable."""
def __init__(self, repository, key, manifest, name, cache=None, create=False,
checkpoint_interval=300, numeric_owner=False):
self.cwd = os.getcwd()
self.key = key
self.repository = repository
self.cache = cache
self.manifest = manifest
self.hard_links = {}
self.stats = Statistics()
self.name = name
self.checkpoint_interval = checkpoint_interval
self.numeric_owner = numeric_owner
self.pipeline = DownloadPipeline(self.repository, self.key)
if create:
self.items_buffer = CacheChunkBuffer(self.cache, self.key, self.stats)
self.chunker = Chunker(WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, self.key.chunk_seed)
if name in manifest.archives:
raise self.AlreadyExists(name)
self.last_checkpoint = time.time()
i = 0
while True:
self.checkpoint_name = '%s.checkpoint%s' % (name, i and ('.%d' % i) or '')
if not self.checkpoint_name in manifest.archives:
break
i += 1
else:
if name not in self.manifest.archives:
raise self.DoesNotExist(name)
info = self.manifest.archives[name]
self.load(info[b'id'])
def load(self, id):
self.id = id
data = self.key.decrypt(self.id, self.repository.get(self.id))
self.metadata = msgpack.unpackb(data)
if self.metadata[b'version'] != 1:
raise Exception('Unknown archive metadata version')
decode_dict(self.metadata, (b'name', b'hostname', b'username', b'time'))
self.metadata[b'cmdline'] = [arg.decode('utf-8', 'surrogateescape') for arg in self.metadata[b'cmdline']]
self.name = self.metadata[b'name']
@property
def ts(self):
"""Timestamp of archive creation in UTC"""
return parse_timestamp(self.metadata[b'time'])
def __repr__(self):
return 'Archive(%r)' % self.name
def iter_items(self, filter=None, preload=False):
for item in self.pipeline.unpack_many(self.metadata[b'items'], filter=filter, preload=preload):
yield item
def add_item(self, item):
self.items_buffer.add(item)
if time.time() - self.last_checkpoint > self.checkpoint_interval:
self.write_checkpoint()
self.last_checkpoint = time.time()
def write_checkpoint(self):
self.save(self.checkpoint_name)
del self.manifest.archives[self.checkpoint_name]
self.cache.chunk_decref(self.id, self.stats)
def save(self, name=None):
name = name or self.name
if name in self.manifest.archives:
raise self.AlreadyExists(name)
self.items_buffer.flush(flush=True)
metadata = StableDict({
'version': 1,
'name': name,
'items': self.items_buffer.chunks,
'cmdline': sys.argv,
'hostname': socket.gethostname(),
'username': getuser(),
'time': datetime.utcnow().isoformat(),
})
data = msgpack.packb(metadata, unicode_errors='surrogateescape')
self.id = self.key.id_hash(data)
self.cache.add_chunk(self.id, data, self.stats)
self.manifest.archives[name] = {'id': self.id, 'time': metadata['time']}
self.manifest.write()
self.repository.commit()
self.cache.commit()
def calc_stats(self, cache):
def add(id):
count, size, csize = cache.chunks[id]
stats.update(size, csize, count == 1)
cache.chunks[id] = count - 1, size, csize
def add_file_chunks(chunks):
for id, _, _ in chunks:
add(id)
# This function is a bit evil since it abuses the cache to calculate
# the stats. The cache transaction must be rolled back afterwards
unpacker = msgpack.Unpacker(use_list=False)
cache.begin_txn()
stats = Statistics()
add(self.id)
for id, chunk in zip(self.metadata[b'items'], self.repository.get_many(self.metadata[b'items'])):
add(id)
unpacker.feed(self.key.decrypt(id, chunk))
for item in unpacker:
if b'chunks' in item:
stats.nfiles += 1
add_file_chunks(item[b'chunks'])
cache.rollback()
return stats
def extract_item(self, item, restore_attrs=True, dry_run=False):
if dry_run:
if b'chunks' in item:
for _ in self.pipeline.fetch_many([c[0] for c in item[b'chunks']], is_preloaded=True):
pass
return
dest = self.cwd
if item[b'path'].startswith('/') or item[b'path'].startswith('..'):
raise Exception('Path should be relative and local')
path = os.path.join(dest, item[b'path'])
# Attempt to remove existing files, ignore errors on failure
try:
st = os.lstat(path)
if stat.S_ISDIR(st.st_mode):
os.rmdir(path)
else:
os.unlink(path)
except UnicodeEncodeError:
raise self.IncompatibleFilesystemEncodingError(path, sys.getfilesystemencoding())
except OSError:
pass
mode = item[b'mode']
if stat.S_ISDIR(mode):
if not os.path.exists(path):
os.makedirs(path)
if restore_attrs:
self.restore_attrs(path, item)
elif stat.S_ISREG(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
# Hard link?
if b'source' in item:
source = os.path.join(dest, item[b'source'])
if os.path.exists(path):
os.unlink(path)
os.link(source, path)
else:
with open(path, 'wb') as fd:
ids = [c[0] for c in item[b'chunks']]
for data in self.pipeline.fetch_many(ids, is_preloaded=True):
fd.write(data)
fd.flush()
self.restore_attrs(path, item, fd=fd.fileno())
elif stat.S_ISFIFO(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
os.mkfifo(path)
self.restore_attrs(path, item)
elif stat.S_ISLNK(mode):
if not os.path.exists(os.path.dirname(path)):
os.makedirs(os.path.dirname(path))
source = item[b'source']
if os.path.exists(path):
os.unlink(path)
os.symlink(source, path)
self.restore_attrs(path, item, symlink=True)
elif stat.S_ISCHR(mode) or stat.S_ISBLK(mode):
os.mknod(path, item[b'mode'], item[b'rdev'])
self.restore_attrs(path, item)
else:
raise Exception('Unknown archive item type %r' % item[b'mode'])
def restore_attrs(self, path, item, symlink=False, fd=None):
xattrs = item.get(b'xattrs')
if xattrs:
for k, v in xattrs.items():
try:
xattr.setxattr(fd or path, k, v, follow_symlinks=False)
except OSError as e:
if e.errno != errno.ENOTSUP:
raise
uid = gid = None
if not self.numeric_owner:
uid = user2uid(item[b'user'])
gid = group2gid(item[b'group'])
uid = item[b'uid'] if uid is None else uid
gid = item[b'gid'] if gid is None else gid
# This code is a bit of a mess due to os specific differences
try:
if fd:
os.fchown(fd, uid, gid)
else:
os.lchown(path, uid, gid)
except OSError:
pass
if fd:
os.fchmod(fd, item[b'mode'])
elif not symlink:
os.chmod(path, item[b'mode'])
elif has_lchmod: # Not available on Linux
os.lchmod(path, item[b'mode'])
mtime = bigint_to_int(item[b'mtime'])
if fd and utime_supports_fd: # Python >= 3.3
os.utime(fd, None, ns=(mtime, mtime))
elif utime_supports_follow_symlinks: # Python >= 3.3
os.utime(path, None, ns=(mtime, mtime), follow_symlinks=False)
elif not symlink:
os.utime(path, (mtime / 1e9, mtime / 1e9))
acl_set(path, item, self.numeric_owner)
# Only available on OS X and FreeBSD
if has_lchflags and b'bsdflags' in item:
try:
os.lchflags(path, item[b'bsdflags'])
except OSError:
pass
def delete(self, stats):
unpacker = msgpack.Unpacker(use_list=False)
for items_id, data in zip(self.metadata[b'items'], self.repository.get_many(self.metadata[b'items'])):
unpacker.feed(self.key.decrypt(items_id, data))
self.cache.chunk_decref(items_id, stats)
for item in unpacker:
if b'chunks' in item:
for chunk_id, size, csize in item[b'chunks']:
self.cache.chunk_decref(chunk_id, stats)
self.cache.chunk_decref(self.id, stats)
del self.manifest.archives[self.name]
def stat_attrs(self, st, path):
item = {
b'mode': st.st_mode,
b'uid': st.st_uid, b'user': uid2user(st.st_uid),
b'gid': st.st_gid, b'group': gid2group(st.st_gid),
b'mtime': int_to_bigint(st_mtime_ns(st))
}
if self.numeric_owner:
item[b'user'] = item[b'group'] = None
xattrs = xattr.get_all(path, follow_symlinks=False)
if xattrs:
item[b'xattrs'] = StableDict(xattrs)
if has_lchflags and st.st_flags:
item[b'bsdflags'] = st.st_flags
acl_get(path, item, st, self.numeric_owner)
return item
def process_item(self, path, st):
item = {b'path': make_path_safe(path)}
item.update(self.stat_attrs(st, path))
self.add_item(item)
def process_dev(self, path, st):
item = {b'path': make_path_safe(path), b'rdev': st.st_rdev}
item.update(self.stat_attrs(st, path))
self.add_item(item)
def process_symlink(self, path, st):
source = os.readlink(path)
item = {b'path': make_path_safe(path), b'source': source}
item.update(self.stat_attrs(st, path))
self.add_item(item)
def process_file(self, path, st, cache):
safe_path = make_path_safe(path)
# Is it a hard link?
if st.st_nlink > 1:
source = self.hard_links.get((st.st_ino, st.st_dev))
if (st.st_ino, st.st_dev) in self.hard_links:
item = self.stat_attrs(st, path)
item.update({b'path': safe_path, b'source': source})
self.add_item(item)
return
else:
self.hard_links[st.st_ino, st.st_dev] = safe_path
path_hash = self.key.id_hash(os.path.join(self.cwd, path).encode('utf-8', 'surrogateescape'))
ids = cache.file_known_and_unchanged(path_hash, st)
chunks = None
if ids is not None:
# Make sure all ids are available
for id_ in ids:
if not cache.seen_chunk(id_):
break
else:
chunks = [cache.chunk_incref(id_, self.stats) for id_ in ids]
# Only chunkify the file if needed
if chunks is None:
with Archive._open_rb(path, st) as fd:
chunks = []
for chunk in self.chunker.chunkify(fd):
chunks.append(cache.add_chunk(self.key.id_hash(chunk), chunk, self.stats))
cache.memorize_file(path_hash, st, [c[0] for c in chunks])
item = {b'path': safe_path, b'chunks': chunks}
item.update(self.stat_attrs(st, path))
self.stats.nfiles += 1
self.add_item(item)
@staticmethod
def list_archives(repository, key, manifest, cache=None):
for name, info in manifest.archives.items():
yield Archive(repository, key, manifest, name, cache=cache)
@staticmethod
def _open_rb(path, st):
flags_noatime = None
euid = None
def open_simple(p, s):
return open(p, 'rb')
def open_noatime_if_owner(p, s):
if s.st_uid == euid:
return os.fdopen(os.open(p, flags_noatime), 'rb')
else:
return open(p, 'rb')
def open_noatime(p, s):
try:
fd = os.open(p, flags_noatime)
except PermissionError:
# Was this EPERM due to the O_NOATIME flag?
fo = open(p, 'rb')
# Yes, it was -- otherwise the above line would have thrown
# another exception.
euid = os.geteuid()
# So in future, let's check whether the file is owned by us
# before attempting to use O_NOATIME.
Archive._open_rb = open_noatime_if_owner
return fo
return os.fdopen(fd, 'rb')
o_noatime = getattr(os, 'O_NOATIME', None)
if o_noatime is not None:
flags_noatime = os.O_RDONLY | getattr(os, 'O_BINARY', 0) | o_noatime
# Always use O_NOATIME version.
Archive._open_rb = open_noatime
else:
# Always use non-O_NOATIME version.
Archive._open_rb = open_simple
return Archive._open_rb(path, st)
class RobustUnpacker():
"""A restartable/robust version of the streaming msgpack unpacker
"""
item_keys = [msgpack.packb(name) for name in ('path', 'mode', 'source', 'chunks', 'rdev', 'xattrs', 'user', 'group', 'uid', 'gid', 'mtime')]
def __init__(self, validator):
super(RobustUnpacker, self).__init__()
self.validator = validator
self._buffered_data = []
self._resync = False
self._unpacker = msgpack.Unpacker(object_hook=StableDict)
def resync(self):
self._buffered_data = []
self._resync = True
def feed(self, data):
if self._resync:
self._buffered_data.append(data)
else:
self._unpacker.feed(data)
def __iter__(self):
return self
def __next__(self):
if self._resync:
data = b''.join(self._buffered_data)
while self._resync:
if not data:
raise StopIteration
# Abort early if the data does not look like a serialized dict
if len(data) < 2 or ((data[0] & 0xf0) != 0x80) or ((data[1] & 0xe0) != 0xa0):
data = data[1:]
continue
# Make sure it looks like an item dict
for pattern in self.item_keys:
if data[1:].startswith(pattern):
break
else:
data = data[1:]
continue
self._unpacker = msgpack.Unpacker(object_hook=StableDict)
self._unpacker.feed(data)
try:
item = next(self._unpacker)
if self.validator(item):
self._resync = False
return item
# Ignore exceptions that might be raised when feeding
# msgpack with invalid data
except (TypeError, ValueError, StopIteration):
pass
data = data[1:]
else:
return next(self._unpacker)
class ArchiveChecker:
def __init__(self):
self.error_found = False
self.possibly_superseded = set()
self.tmpdir = tempfile.mkdtemp()
def __del__(self):
shutil.rmtree(self.tmpdir)
def check(self, repository, repair=False):
self.report_progress('Starting archive consistency check...')
self.repair = repair
self.repository = repository
self.init_chunks()
self.key = self.identify_key(repository)
if not Manifest.MANIFEST_ID in self.chunks:
self.manifest = self.rebuild_manifest()
else:
self.manifest, _ = Manifest.load(repository, key=self.key)
self.rebuild_refcounts()
self.verify_chunks()
if not self.error_found:
self.report_progress('Archive consistency check complete, no problems found.')
return self.repair or not self.error_found
def init_chunks(self):
"""Fetch a list of all object keys from repository
"""
# Explicity set the initial hash table capacity to avoid performance issues
# due to hash table "resonance"
capacity = int(len(self.repository) * 1.2)
self.chunks = ChunkIndex(capacity)
marker = None
while True:
result = self.repository.list(limit=10000, marker=marker)
if not result:
break
marker = result[-1]
for id_ in result:
self.chunks[id_] = (0, 0, 0)
def report_progress(self, msg, error=False):
if error:
self.error_found = True
print(msg, file=sys.stderr if error else sys.stdout)
def identify_key(self, repository):
cdata = repository.get(next(self.chunks.iteritems())[0])
return key_factory(repository, cdata)
def rebuild_manifest(self):
"""Rebuild the manifest object if it is missing
Iterates through all objects in the repository looking for archive metadata blocks.
"""
self.report_progress('Rebuilding missing manifest, this might take some time...', error=True)
manifest = Manifest(self.key, self.repository)
for chunk_id, _ in self.chunks.iteritems():
cdata = self.repository.get(chunk_id)
data = self.key.decrypt(chunk_id, cdata)
# Some basic sanity checks of the payload before feeding it into msgpack
if len(data) < 2 or ((data[0] & 0xf0) != 0x80) or ((data[1] & 0xe0) != 0xa0):
continue
if not b'cmdline' in data or not b'\xa7version\x01' in data:
continue
try:
archive = msgpack.unpackb(data)
except:
continue
if isinstance(archive, dict) and b'items' in archive and b'cmdline' in archive:
self.report_progress('Found archive ' + archive[b'name'].decode('utf-8'), error=True)
manifest.archives[archive[b'name'].decode('utf-8')] = {b'id': chunk_id, b'time': archive[b'time']}
self.report_progress('Manifest rebuild complete', error=True)
return manifest
def rebuild_refcounts(self):
"""Rebuild object reference counts by walking the metadata
Missing and/or incorrect data is repaired when detected
"""
# Exclude the manifest from chunks
del self.chunks[Manifest.MANIFEST_ID]
def mark_as_possibly_superseded(id_):
if self.chunks.get(id_, (0,))[0] == 0:
self.possibly_superseded.add(id_)
def add_callback(chunk):
id_ = self.key.id_hash(chunk)
cdata = self.key.encrypt(chunk)
add_reference(id_, len(chunk), len(cdata), cdata)
return id_
def add_reference(id_, size, csize, cdata=None):
try:
count, _, _ = self.chunks[id_]
self.chunks[id_] = count + 1, size, csize
except KeyError:
assert cdata is not None
self.chunks[id_] = 1, size, csize
if self.repair:
self.repository.put(id_, cdata)
def verify_file_chunks(item):
"""Verifies that all file chunks are present
Missing file chunks will be replaced with new chunks of the same
length containing all zeros.
"""
offset = 0
chunk_list = []
for chunk_id, size, csize in item[b'chunks']:
if not chunk_id in self.chunks:
# If a file chunk is missing, create an all empty replacement chunk
self.report_progress('{}: Missing file chunk detected (Byte {}-{})'.format(item[b'path'].decode('utf-8', 'surrogateescape'), offset, offset + size), error=True)
data = bytes(size)
chunk_id = self.key.id_hash(data)
cdata = self.key.encrypt(data)
csize = len(cdata)
add_reference(chunk_id, size, csize, cdata)
else:
add_reference(chunk_id, size, csize)
chunk_list.append((chunk_id, size, csize))
offset += size
item[b'chunks'] = chunk_list
def robust_iterator(archive):
"""Iterates through all archive items
Missing item chunks will be skipped and the msgpack stream will be restarted
"""
unpacker = RobustUnpacker(lambda item: isinstance(item, dict) and b'path' in item)
_state = 0
def missing_chunk_detector(chunk_id):
nonlocal _state
if _state % 2 != int(not chunk_id in self.chunks):
_state += 1
return _state
for state, items in groupby(archive[b'items'], missing_chunk_detector):
items = list(items)
if state % 2:
self.report_progress('Archive metadata damage detected', error=True)
continue
if state > 0:
unpacker.resync()
for chunk_id, cdata in zip(items, repository.get_many(items)):
unpacker.feed(self.key.decrypt(chunk_id, cdata))
for item in unpacker:
yield item
repository = cache_if_remote(self.repository)
num_archives = len(self.manifest.archives)
for i, (name, info) in enumerate(list(self.manifest.archives.items()), 1):
self.report_progress('Analyzing archive {} ({}/{})'.format(name, i, num_archives))
archive_id = info[b'id']
if not archive_id in self.chunks:
self.report_progress('Archive metadata block is missing', error=True)
del self.manifest.archives[name]
continue
mark_as_possibly_superseded(archive_id)
cdata = self.repository.get(archive_id)
data = self.key.decrypt(archive_id, cdata)
archive = StableDict(msgpack.unpackb(data))
if archive[b'version'] != 1:
raise Exception('Unknown archive metadata version')
decode_dict(archive, (b'name', b'hostname', b'username', b'time')) # fixme: argv
items_buffer = ChunkBuffer(self.key)
items_buffer.write_chunk = add_callback
for item in robust_iterator(archive):
if b'chunks' in item:
verify_file_chunks(item)
items_buffer.add(item)
items_buffer.flush(flush=True)
for previous_item_id in archive[b'items']:
mark_as_possibly_superseded(previous_item_id)
archive[b'items'] = items_buffer.chunks
data = msgpack.packb(archive, unicode_errors='surrogateescape')
new_archive_id = self.key.id_hash(data)
cdata = self.key.encrypt(data)
add_reference(new_archive_id, len(data), len(cdata), cdata)
info[b'id'] = new_archive_id
def verify_chunks(self):
unused = set()
for id_, (count, size, csize) in self.chunks.iteritems():
if count == 0:
unused.add(id_)
orphaned = unused - self.possibly_superseded
if orphaned:
self.report_progress('{} orphaned objects found'.format(len(orphaned)), error=True)
if self.repair:
for id_ in unused:
self.repository.delete(id_)
self.manifest.write()
self.repository.commit()