Source code for borg.fuse

from collections import defaultdict
import errno
import io
import llfuse
import os
import stat
import tempfile
import time
from signal import SIGINT
from distutils.version import LooseVersion

import msgpack

from .archive import Archive
from .helpers import daemonize, bigint_to_int
from .logger import create_logger
from .lrucache import LRUCache
logger = create_logger()


# Does this version of llfuse support ns precision?
have_fuse_xtime_ns = hasattr(llfuse.EntryAttributes, 'st_mtime_ns')

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