mirror of
https://github.com/borgbackup/borg.git
synced 2026-03-02 05:20:30 -05:00
337 lines
12 KiB
Python
337 lines
12 KiB
Python
import errno
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import io
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import os
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import stat
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import tempfile
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import time
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from collections import defaultdict
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from distutils.version import LooseVersion
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from zlib import adler32
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import llfuse
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import msgpack
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from .logger import create_logger
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logger = create_logger()
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from .archive import Archive
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from .helpers import daemonize, safe_encode
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from .item import Item
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from .lrucache import LRUCache
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# Does this version of llfuse support ns precision?
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have_fuse_xtime_ns = hasattr(llfuse.EntryAttributes, 'st_mtime_ns')
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fuse_version = LooseVersion(getattr(llfuse, '__version__', '0.1'))
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if fuse_version >= '0.42':
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def fuse_main():
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return llfuse.main(workers=1)
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else:
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def fuse_main():
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llfuse.main(single=True)
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return None
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class ItemCache:
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def __init__(self):
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self.fd = tempfile.TemporaryFile(prefix='borg-tmp')
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self.offset = 1000000
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def add(self, item):
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pos = self.fd.seek(0, io.SEEK_END)
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self.fd.write(msgpack.packb(item.as_dict()))
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return pos + self.offset
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def get(self, inode):
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self.fd.seek(inode - self.offset, io.SEEK_SET)
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item = next(msgpack.Unpacker(self.fd, read_size=1024))
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return Item(internal_dict=item)
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class FuseOperations(llfuse.Operations):
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"""Export archive as a fuse filesystem
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"""
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# mount options
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allow_damaged_files = False
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versions = False
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def __init__(self, key, repository, manifest, archive, cached_repo):
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super().__init__()
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self.repository_uncached = repository
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self.repository = cached_repo
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self.archive = archive
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self.manifest = manifest
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self.key = key
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self._inode_count = 0
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self.items = {}
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self.parent = {}
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self.contents = defaultdict(dict)
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self.default_dir = Item(mode=0o40755, mtime=int(time.time() * 1e9), uid=os.getuid(), gid=os.getgid())
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self.pending_archives = {}
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self.accounted_chunks = {}
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self.cache = ItemCache()
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data_cache_capacity = int(os.environ.get('BORG_MOUNT_DATA_CACHE_ENTRIES', os.cpu_count() or 1))
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logger.debug('mount data cache capacity: %d chunks', data_cache_capacity)
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self.data_cache = LRUCache(capacity=data_cache_capacity, dispose=lambda _: None)
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def _create_filesystem(self):
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self._create_dir(parent=1) # first call, create root dir (inode == 1)
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if self.archive:
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self.process_archive(self.archive)
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else:
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for name in self.manifest.archives:
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archive = Archive(self.repository_uncached, self.key, self.manifest, name)
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if self.versions:
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# process archives immediately
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self.process_archive(archive)
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else:
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# lazy load archives, create archive placeholder inode
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archive_inode = self._create_dir(parent=1)
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self.contents[1][os.fsencode(name)] = archive_inode
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self.pending_archives[archive_inode] = archive
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def mount(self, mountpoint, mount_options, foreground=False):
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"""Mount filesystem on *mountpoint* with *mount_options*."""
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options = ['fsname=borgfs', 'ro']
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if mount_options:
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options.extend(mount_options.split(','))
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try:
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options.remove('allow_damaged_files')
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self.allow_damaged_files = True
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except ValueError:
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pass
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try:
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options.remove('versions')
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self.versions = True
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except ValueError:
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pass
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self._create_filesystem()
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llfuse.init(self, mountpoint, options)
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if not foreground:
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daemonize()
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# If the file system crashes, we do not want to umount because in that
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# case the mountpoint suddenly appears to become empty. This can have
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# nasty consequences, imagine the user has e.g. an active rsync mirror
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# job - seeing the mountpoint empty, rsync would delete everything in the
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# mirror.
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umount = False
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try:
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signal = fuse_main()
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umount = (signal is None) # no crash and no signal -> umount request
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finally:
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llfuse.close(umount)
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def _create_dir(self, parent):
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"""Create directory
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"""
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ino = self.allocate_inode()
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self.items[ino] = self.default_dir
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self.parent[ino] = parent
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return ino
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def process_archive(self, archive, prefix=[]):
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"""Build fuse inode hierarchy from archive metadata
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"""
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unpacker = msgpack.Unpacker()
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for key, chunk in zip(archive.metadata.items, self.repository.get_many(archive.metadata.items)):
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_, data = self.key.decrypt(key, chunk)
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unpacker.feed(data)
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for item in unpacker:
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item = Item(internal_dict=item)
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is_dir = stat.S_ISDIR(item.mode)
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if is_dir:
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try:
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# This can happen if an archive was created with a command line like
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# $ borg create ... dir1/file dir1
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# In this case the code below will have created a default_dir inode for dir1 already.
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inode = self._find_inode(item.path, prefix)
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except KeyError:
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pass
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else:
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self.items[inode] = item
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continue
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segments = prefix + os.fsencode(os.path.normpath(item.path)).split(b'/')
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del item.path
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parent = 1
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for segment in segments[:-1]:
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parent = self.process_inner(segment, parent)
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self.process_leaf(segments[-1], item, parent, prefix, is_dir)
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def process_leaf(self, name, item, parent, prefix, is_dir):
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def version_name(name, item):
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if 'chunks' in item:
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ident = 0
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for chunkid, _, _ in item.chunks:
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ident = adler32(chunkid, ident)
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name = name + safe_encode('.%08x' % ident)
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return name
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if self.versions and not is_dir:
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parent = self.process_inner(name, parent)
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name = version_name(name, item)
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if 'source' in item and stat.S_ISREG(item.mode):
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inode = self._find_inode(item.source, prefix)
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item = self.cache.get(inode)
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item.nlink = item.get('nlink', 1) + 1
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self.items[inode] = item
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else:
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inode = self.cache.add(item)
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self.parent[inode] = parent
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if name:
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self.contents[parent][name] = inode
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def process_inner(self, name, parent_inode):
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dir = self.contents[parent_inode]
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if name in dir:
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inode = dir[name]
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else:
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inode = self._create_dir(parent_inode)
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if name:
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dir[name] = inode
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return inode
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def allocate_inode(self):
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self._inode_count += 1
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return self._inode_count
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def statfs(self, ctx=None):
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stat_ = llfuse.StatvfsData()
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stat_.f_bsize = 512
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stat_.f_frsize = 512
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stat_.f_blocks = 0
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stat_.f_bfree = 0
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stat_.f_bavail = 0
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stat_.f_files = 0
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stat_.f_ffree = 0
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stat_.f_favail = 0
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return stat_
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def get_item(self, inode):
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try:
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return self.items[inode]
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except KeyError:
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return self.cache.get(inode)
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def _find_inode(self, path, prefix=[]):
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segments = prefix + os.fsencode(os.path.normpath(path)).split(b'/')
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inode = 1
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for segment in segments:
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inode = self.contents[inode][segment]
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return inode
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def getattr(self, inode, ctx=None):
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item = self.get_item(inode)
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size = 0
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dsize = 0
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if 'chunks' in item:
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for key, chunksize, _ in item.chunks:
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size += chunksize
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if self.accounted_chunks.get(key, inode) == inode:
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self.accounted_chunks[key] = inode
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dsize += chunksize
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entry = llfuse.EntryAttributes()
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entry.st_ino = inode
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entry.generation = 0
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entry.entry_timeout = 300
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entry.attr_timeout = 300
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entry.st_mode = item.mode
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entry.st_nlink = item.get('nlink', 1)
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entry.st_uid = item.uid
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entry.st_gid = item.gid
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entry.st_rdev = item.get('rdev', 0)
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entry.st_size = size
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entry.st_blksize = 512
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entry.st_blocks = dsize / 512
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# note: older archives only have mtime (not atime nor ctime)
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mtime_ns = item.mtime
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if have_fuse_xtime_ns:
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entry.st_mtime_ns = mtime_ns
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entry.st_atime_ns = item.get('atime', mtime_ns)
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entry.st_ctime_ns = item.get('ctime', mtime_ns)
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else:
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entry.st_mtime = mtime_ns / 1e9
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entry.st_atime = item.get('atime', mtime_ns) / 1e9
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entry.st_ctime = item.get('ctime', mtime_ns) / 1e9
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return entry
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def listxattr(self, inode, ctx=None):
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item = self.get_item(inode)
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return item.get('xattrs', {}).keys()
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def getxattr(self, inode, name, ctx=None):
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item = self.get_item(inode)
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try:
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return item.get('xattrs', {})[name]
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except KeyError:
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raise llfuse.FUSEError(llfuse.ENOATTR) from None
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def _load_pending_archive(self, inode):
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# Check if this is an archive we need to load
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archive = self.pending_archives.pop(inode, None)
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if archive:
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self.process_archive(archive, [os.fsencode(archive.name)])
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def lookup(self, parent_inode, name, ctx=None):
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self._load_pending_archive(parent_inode)
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if name == b'.':
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inode = parent_inode
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elif name == b'..':
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inode = self.parent[parent_inode]
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else:
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inode = self.contents[parent_inode].get(name)
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if not inode:
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raise llfuse.FUSEError(errno.ENOENT)
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return self.getattr(inode)
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def open(self, inode, flags, ctx=None):
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if not self.allow_damaged_files:
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item = self.get_item(inode)
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if 'chunks_healthy' in item:
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# Processed archive items don't carry the path anymore; for converting the inode
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# to the path we'd either have to store the inverse of the current structure,
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# or search the entire archive. So we just don't print it. It's easy to correlate anyway.
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logger.warning('File has damaged (all-zero) chunks. Try running borg check --repair. '
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'Mount with allow_damaged_files to read damaged files.')
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raise llfuse.FUSEError(errno.EIO)
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return inode
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def opendir(self, inode, ctx=None):
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self._load_pending_archive(inode)
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return inode
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def read(self, fh, offset, size):
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parts = []
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item = self.get_item(fh)
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for id, s, csize in item.chunks:
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if s < offset:
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offset -= s
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continue
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n = min(size, s - offset)
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if id in self.data_cache:
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data = self.data_cache[id]
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if offset + n == len(data):
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# evict fully read chunk from cache
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del self.data_cache[id]
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else:
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_, data = self.key.decrypt(id, self.repository.get(id))
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if offset + n < len(data):
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# chunk was only partially read, cache it
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self.data_cache[id] = data
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parts.append(data[offset:offset + n])
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offset = 0
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size -= n
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if not size:
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break
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return b''.join(parts)
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def readdir(self, fh, off):
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entries = [(b'.', fh), (b'..', self.parent[fh])]
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entries.extend(self.contents[fh].items())
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for i, (name, inode) in enumerate(entries[off:], off):
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yield name, self.getattr(inode), i + 1
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def readlink(self, inode, ctx=None):
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item = self.get_item(inode)
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return os.fsencode(item.source)
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