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borg/attic/archive.py
2013-08-12 22:47:25 +02:00

409 lines
15 KiB
Python

from datetime import datetime, timedelta
from getpass import getuser
from itertools import zip_longest
import msgpack
import os
import socket
import stat
import sys
import time
from io import BytesIO
from attic import xattr
from attic.chunker import chunkify
from attic.helpers import uid2user, user2uid, gid2group, group2gid, \
Statistics, decode_dict, st_mtime_ns, make_path_safe
ITEMS_BUFFER = 1024 * 1024
CHUNK_MIN = 1024
WINDOW_SIZE = 0xfff
CHUNK_MASK = 0xffff
utime_supports_fd = os.utime in getattr(os, 'supports_fd', {})
has_mtime_ns = sys.version >= '3.3'
has_lchmod = hasattr(os, 'lchmod')
class ItemIter(object):
def __init__(self, unpacker, filter):
self.unpacker = iter(unpacker)
self.filter = filter
self.stack = []
self.peeks = 0
self._peek_iter = None
def __iter__(self):
return self
def __next__(self):
if self.stack:
item = self.stack.pop(0)
else:
self._peek_iter = None
item = self.get_next()
self.peeks = max(0, self.peeks - len(item.get(b'chunks', [])))
return item
def get_next(self):
while True:
n = next(self.unpacker)
decode_dict(n, (b'path', b'source', b'user', b'group'))
if not self.filter or self.filter(n):
return n
def peek(self):
while True:
while not self._peek_iter:
if self.peeks > 100:
raise StopIteration
_peek = self.get_next()
self.stack.append(_peek)
if b'chunks' in _peek:
self._peek_iter = iter(_peek[b'chunks'])
else:
self._peek_iter = None
try:
item = next(self._peek_iter)
self.peeks += 1
return item
except StopIteration:
self._peek_iter = None
class Archive(object):
class DoesNotExist(Exception):
pass
class AlreadyExists(Exception):
pass
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.items = BytesIO()
self.items_ids = []
self.hard_links = {}
self.stats = Statistics()
self.name = name
self.checkpoint_interval = checkpoint_interval
self.numeric_owner = numeric_owner
if create:
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"""
t, f = self.metadata[b'time'].split('.', 1)
return datetime.strptime(t, '%Y-%m-%dT%H:%M:%S') + timedelta(seconds=float('.' + f))
def __repr__(self):
return 'Archive(%r)' % self.name
def iter_items(self, filter=None):
unpacker = msgpack.Unpacker(use_list=False)
i = 0
n = 20
while True:
items = self.metadata[b'items'][i:i + n]
i += n
if not items:
break
for id, chunk in [(id, chunk) for id, chunk in zip_longest(items, self.repository.get_many(items))]:
unpacker.feed(self.key.decrypt(id, chunk))
iter = ItemIter(unpacker, filter)
for item in iter:
yield item, iter.peek
def add_item(self, item):
self.items.write(msgpack.packb(item, unicode_errors='surrogateescape'))
now = time.time()
if now - self.last_checkpoint > self.checkpoint_interval:
self.last_checkpoint = now
self.write_checkpoint()
if self.items.tell() > ITEMS_BUFFER:
self.flush_items()
def flush_items(self, flush=False):
if self.items.tell() == 0:
return
self.items.seek(0)
chunks = list(bytes(s) for s in chunkify(self.items, WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, self.key.chunk_seed))
self.items.seek(0)
self.items.truncate()
for chunk in chunks[:-1]:
id, _, _ = self.cache.add_chunk(self.key.id_hash(chunk), chunk, self.stats)
self.items_ids.append(id)
if flush or len(chunks) == 1:
id, _, _ = self.cache.add_chunk(self.key.id_hash(chunks[-1]), chunks[-1], self.stats)
self.items_ids.append(id)
else:
self.items.write(chunks[-1])
def write_checkpoint(self):
self.save(self.checkpoint_name)
del self.manifest.archives[self.checkpoint_name]
self.cache.chunk_decref(self.id)
def save(self, name=None):
name = name or self.name
if name in self.manifest.archives:
raise self.AlreadyExists(name)
self.flush_items(flush=True)
metadata = {
'version': 1,
'name': name,
'items': self.items_ids,
'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 = self.cache.chunks[id]
stats.update(size, csize, count == 1)
self.cache.chunks[id] = count - 1, size, csize
# 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_longest(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:
try:
for id, size, csize in item[b'chunks']:
add(id)
stats.nfiles += 1
except KeyError:
pass
cache.rollback()
return stats
def extract_item(self, item, restore_attrs=True, peek=None):
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 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 = [id for id, size, csize in item[b'chunks']]
for id, chunk in zip_longest(ids, self.repository.get_many(ids, peek)):
data = self.key.decrypt(id, chunk)
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():
xattr.setxattr(fd or path, k, v)
uid = gid = None
if not self.numeric_owner:
uid = user2uid(item[b'user'])
gid = group2gid(item[b'group'])
uid = uid or item[b'uid']
gid = gid or item[b'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'])
if fd and utime_supports_fd: # Python >= 3.3
os.utime(fd, None, ns=(item[b'mtime'], item[b'mtime']))
elif utime_supports_fd: # Python >= 3.3
os.utime(path, None, ns=(item[b'mtime'], item[b'mtime']), follow_symlinks=False)
elif not symlink:
os.utime(path, (item[b'mtime'] / 10**9, item[b'mtime'] / 10**9))
def verify_file(self, item, start, result, peek=None):
if not item[b'chunks']:
start(item)
result(item, True)
else:
start(item)
ids = [id for id, size, csize in item[b'chunks']]
try:
for id, chunk in zip_longest(ids, self.repository.get_many(ids, peek)):
self.key.decrypt(id, chunk)
except Exception:
result(item, False)
return
result(item, True)
def delete(self, cache):
unpacker = msgpack.Unpacker(use_list=False)
for id in self.metadata[b'items']:
unpacker.feed(self.key.decrypt(id, self.repository.get(id)))
for item in unpacker:
try:
for chunk_id, size, csize in item[b'chunks']:
self.cache.chunk_decref(chunk_id)
except KeyError:
pass
self.cache.chunk_decref(id)
self.cache.chunk_decref(self.id)
del self.manifest.archives[self.name]
self.manifest.write()
self.repository.commit()
cache.commit()
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': 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'] = xattrs
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 open(path, 'rb') as fd:
chunks = []
for chunk in chunkify(fd, WINDOW_SIZE, CHUNK_MASK, CHUNK_MIN, self.key.chunk_seed):
chunks.append(cache.add_chunk(self.key.id_hash(chunk), chunk, self.stats))
ids = [id for id, _, _ in chunks]
cache.memorize_file(path_hash, st, ids)
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)