241 lines
8.6 KiB
Python
241 lines
8.6 KiB
Python
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"""
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fuse.py — FUSE filesystem layer for Trove, backed by pyfuse3 + trio.
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Blob objects are exposed as regular files.
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Tree objects are exposed as directories.
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Inode numbers map 1:1 to Trove object IDs (NODE_ROOT_ID == pyfuse3 root inode == 1).
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Entry point: serve(trove, mountpoint)
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"""
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import errno
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import os
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import stat
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import time
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import pyfuse3
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import trio
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from trovedb.trove import Trove, Note, Tree as TroveTree, TreeNote, Blob as TroveBlob
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class TroveFuseOps(pyfuse3.Operations):
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enable_writeback_cache = False
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def __init__(self, trove: Trove):
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super().__init__()
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self._trove = trove
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# ------------------------------------------------------------------
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# Helpers
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# ------------------------------------------------------------------
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def _note_or_error(self, inode: int):
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note = self._trove.get_raw_note(inode)
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if note is None:
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raise pyfuse3.FUSEError(errno.ENOENT)
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return note
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def _make_attr(self, inode: int, is_tree: bool, size: int = 0) -> pyfuse3.EntryAttributes:
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attr = pyfuse3.EntryAttributes()
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attr.st_ino = pyfuse3.InodeT(inode)
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attr.st_nlink = 1
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attr.st_uid = os.getuid()
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attr.st_gid = os.getgid()
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now_ns = int(time.time() * 1e9)
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attr.st_atime_ns = now_ns
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attr.st_mtime_ns = now_ns
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attr.st_ctime_ns = now_ns
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attr.generation = 0
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attr.entry_timeout = 5.0
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attr.attr_timeout = 5.0
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if is_tree:
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attr.st_mode = stat.S_IFDIR | 0o755
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attr.st_size = 0
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attr.st_blksize = 512
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attr.st_blocks = 0
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else:
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attr.st_mode = stat.S_IFREG | 0o644
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attr.st_size = size
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attr.st_blksize = 512
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attr.st_blocks = (size + 511) // 512
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return attr
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def _attr_for_note(self, note: Note) -> pyfuse3.EntryAttributes:
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size = 0
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is_tree = True
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if isinstance(note, TroveBlob):
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size = len(note.read())
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is_tree = False
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return self._make_attr(note.object_id, is_tree, size)
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# ------------------------------------------------------------------
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# Stat / lookup
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# ------------------------------------------------------------------
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async def getattr(self, inode: int, ctx=None) -> pyfuse3.EntryAttributes:
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note = self._note_or_error(inode)
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return self._attr_for_note(note)
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async def lookup(self, parent_inode: int, name: bytes, ctx=None) -> pyfuse3.EntryAttributes:
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parent = self._note_or_error(parent_inode)
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if not isinstance(parent, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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entries = parent.list()
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name_str = name.decode()
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if name_str not in entries:
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raise pyfuse3.FUSEError(errno.ENOENT)
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child = self._trove.get_raw_note(entries[name_str])
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if child is None:
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raise pyfuse3.FUSEError(errno.ENOENT)
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return self._attr_for_note(child)
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async def setattr(self, inode: int, attr, fields, fh, ctx) -> pyfuse3.EntryAttributes:
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note = self._note_or_error(inode)
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if fields.update_size and not isinstance(note, TroveTree):
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current = note.read()
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new_size = attr.st_size
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if new_size < len(current):
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note.write(current[:new_size])
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elif new_size > len(current):
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note.write(current + b"\x00" * (new_size - len(current)))
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return self._attr_for_note(note)
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async def forget(self, inode_list) -> None:
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pass
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# ------------------------------------------------------------------
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# Directory ops
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# ------------------------------------------------------------------
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async def opendir(self, inode: int, ctx) -> pyfuse3.FileHandleT:
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note = self._note_or_error(inode)
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if not isinstance(note, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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return pyfuse3.FileHandleT(inode)
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async def readdir(self, fh: int, start_id: int, token) -> None:
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note = self._note_or_error(fh)
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if not isinstance(note, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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entries = list(note.list().items()) # [(name, object_id), ...]
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for idx, (name, child_id) in enumerate(entries):
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if idx < start_id:
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continue
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child = self._trove.get_raw_note(child_id)
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if child is None:
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continue
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attr = self._attr_for_note(child)
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if not pyfuse3.readdir_reply(token, name.encode(), attr, idx + 1):
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break
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async def releasedir(self, fh: int) -> None:
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pass
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async def mkdir(self, parent_inode: int, name: bytes, mode: int, ctx) -> pyfuse3.EntryAttributes:
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parent = self._note_or_error(parent_inode)
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if not isinstance(parent, TreeNote):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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name_str = name.decode()
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if name_str in parent.list():
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raise pyfuse3.FUSEError(errno.EEXIST)
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new_tree: TreeNote = parent.mkdir(name_str)
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return self._make_attr(new_tree.object_id, True, 0)
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async def rmdir(self, parent_inode: int, name: bytes, ctx) -> None:
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parent = self._note_or_error(parent_inode)
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if not isinstance(parent, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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name_str = name.decode()
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entries = parent.list()
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if name_str not in entries:
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raise pyfuse3.FUSEError(errno.ENOENT)
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child = self._trove.get_raw_note(entries[name_str])
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if child is None:
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raise pyfuse3.FUSEError(errno.ENOENT)
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if not isinstance(child, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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if child.list():
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raise pyfuse3.FUSEError(errno.ENOTEMPTY)
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parent.unlink(name_str)
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# ------------------------------------------------------------------
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# File ops
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# ------------------------------------------------------------------
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async def open(self, inode: int, flags, ctx) -> pyfuse3.FileInfo:
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note = self._note_or_error(inode)
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if isinstance(note, TroveTree):
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raise pyfuse3.FUSEError(errno.EISDIR)
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return pyfuse3.FileInfo(fh=pyfuse3.FileHandleT(inode))
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async def create(self, parent_inode: int, name: bytes, mode: int, flags, ctx) -> tuple:
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parent = self._note_or_error(parent_inode)
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if not isinstance(parent, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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name_str = name.decode()
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if name_str in parent.list():
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raise pyfuse3.FUSEError(errno.EEXIST)
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blob = self._trove.create_blob(b"")
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parent.link(name_str, blob)
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attr = self._make_attr(blob.object_id, False, 0)
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return pyfuse3.FileInfo(fh=pyfuse3.FileHandleT(blob.object_id)), attr
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async def read(self, fh: int, offset: int, length: int) -> bytes:
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note = self._note_or_error(fh)
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return note.read()[offset:offset + length]
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async def write(self, fh: int, offset: int, data: bytes) -> int:
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note = self._note_or_error(fh)
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existing = note.read()
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if offset > len(existing):
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existing = existing + b"\x00" * (offset - len(existing))
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note.write(existing[:offset] + data + existing[offset + len(data):])
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return len(data)
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async def release(self, fh: int) -> None:
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pass
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async def unlink(self, parent_inode: int, name: bytes, ctx) -> None:
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parent = self._note_or_error(parent_inode)
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if not isinstance(parent, TroveTree):
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raise pyfuse3.FUSEError(errno.ENOTDIR)
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name_str = name.decode()
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entries = parent.list()
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if name_str not in entries:
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raise pyfuse3.FUSEError(errno.ENOENT)
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child = self._trove.get_raw_note(entries[name_str])
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if child is None:
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raise pyfuse3.FUSEError(errno.ENOENT)
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if isinstance(child, TroveTree):
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raise pyfuse3.FUSEError(errno.EISDIR)
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parent.unlink(name_str)
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# ------------------------------------------------------------------
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# Serve
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# ------------------------------------------------------------------
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async def _run(ops: TroveFuseOps, mountpoint: str) -> None:
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options = set(pyfuse3.default_options)
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options.add("fsname=trove")
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pyfuse3.init(ops, mountpoint, options)
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try:
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await pyfuse3.main()
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finally:
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pyfuse3.close()
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def serve(trove: Trove, mountpoint: str) -> None:
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"""
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Mount a Trove store at mountpoint and serve until KeyboardInterrupt.
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Runs a trio event loop internally.
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"""
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ops = TroveFuseOps(trove)
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try:
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trio.run(_run, ops, mountpoint)
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except KeyboardInterrupt:
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pass
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