Implement locking of whole storage
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Unrud
parent
8e09c0b315
commit
2c45b1998c
@ -273,32 +273,45 @@ class Application:
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is_authenticated = self.is_authenticated(user, password)
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is_valid_user = is_authenticated or not user
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if is_valid_user:
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items = self.Collection.discover(
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path, environ.get("HTTP_DEPTH", "0"))
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read_allowed_items, write_allowed_items = (
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self.collect_allowed_items(items, user))
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else:
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read_allowed_items, write_allowed_items = None, None
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lock = None
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try:
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if is_valid_user:
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if function in (self.do_GET, self.do_HEAD,
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self.do_OPTIONS, self.do_PROPFIND,
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self.do_REPORT):
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lock_mode = "r"
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else:
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lock_mode = "w"
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lock = self.Collection.acquire_lock(lock_mode)
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# Get content
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content_length = int(environ.get("CONTENT_LENGTH") or 0)
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if content_length:
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content = self.decode(
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environ["wsgi.input"].read(content_length), environ)
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self.logger.debug("Request content:\n%s" % content)
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else:
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content = None
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items = self.Collection.discover(
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path, environ.get("HTTP_DEPTH", "0"))
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read_allowed_items, write_allowed_items = (
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self.collect_allowed_items(items, user))
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else:
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read_allowed_items, write_allowed_items = None, None
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if is_valid_user and (
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(read_allowed_items or write_allowed_items) or
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(is_authenticated and function == self.do_PROPFIND) or
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function == self.do_OPTIONS):
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status, headers, answer = function(
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environ, read_allowed_items, write_allowed_items, content,
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user)
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else:
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status, headers, answer = NOT_ALLOWED
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# Get content
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content_length = int(environ.get("CONTENT_LENGTH") or 0)
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if content_length:
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content = self.decode(
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environ["wsgi.input"].read(content_length), environ)
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self.logger.debug("Request content:\n%s" % content)
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else:
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content = None
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if is_valid_user and (
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(read_allowed_items or write_allowed_items) or
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(is_authenticated and function == self.do_PROPFIND) or
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function == self.do_OPTIONS):
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status, headers, answer = function(
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environ, read_allowed_items, write_allowed_items, content,
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user)
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else:
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status, headers, answer = NOT_ALLOWED
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finally:
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if lock:
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lock.release()
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if (status, headers, answer) == NOT_ALLOWED and not is_authenticated:
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# Unknown or unauthorized user
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@ -29,6 +29,8 @@ import json
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import os
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import posixpath
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import shutil
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import stat
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import threading
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import time
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from contextlib import contextmanager
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from hashlib import md5
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@ -37,6 +39,35 @@ from uuid import uuid4
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import vobject
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if os.name == "nt":
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import ctypes
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import ctypes.wintypes
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import msvcrt
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LOCKFILE_EXCLUSIVE_LOCK = 2
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if ctypes.sizeof(ctypes.c_void_p) == 4:
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ULONG_PTR = ctypes.c_uint32
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else:
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ULONG_PTR = ctypes.c_uint64
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class Overlapped(ctypes.Structure):
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_fields_ = [("internal", ULONG_PTR),
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("internal_high", ULONG_PTR),
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("offset", ctypes.wintypes.DWORD),
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("offset_high", ctypes.wintypes.DWORD),
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("h_event", ctypes.wintypes.HANDLE)]
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lock_file_ex = ctypes.windll.kernel32.LockFileEx
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lock_file_ex.argtypes = [ctypes.wintypes.HANDLE,
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ctypes.wintypes.DWORD,
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ctypes.wintypes.DWORD,
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ctypes.wintypes.DWORD,
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ctypes.wintypes.DWORD,
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ctypes.POINTER(Overlapped)]
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lock_file_ex.restype = ctypes.wintypes.BOOL
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elif os.name == "posix":
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import fcntl
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def load(configuration, logger):
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"""Load the storage manager chosen in configuration."""
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@ -245,6 +276,18 @@ class BaseCollection:
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"""Get the unicode string representing the whole collection."""
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raise NotImplementedError
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@classmethod
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def acquire_lock(cls, mode):
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"""Lock the whole storage.
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``mode`` must either be "r" for shared access or "w" for exclusive
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access.
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Returns an object which has a method ``release``.
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"""
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raise NotImplementedError
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class Collection(BaseCollection):
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"""Collection stored in several files per calendar."""
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@ -474,3 +517,61 @@ class Collection(BaseCollection):
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elif self.get_meta("tag") == "VADDRESSBOOK":
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return "".join([item.serialize() for item in items])
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return ""
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_lock = threading.Lock()
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@classmethod
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def acquire_lock(cls, mode):
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class Lock:
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def __init__(self, release_method):
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self._release_method = release_method
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def release(self):
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self._release_method()
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if mode not in ("r", "w"):
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raise ValueError("Invalid lock mode: %s" % mode)
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folder = os.path.expanduser(
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cls.configuration.get("storage", "filesystem_folder"))
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if not os.path.exists(folder):
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os.makedirs(folder, exist_ok=True)
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lock_path = os.path.join(folder, "Radicale.lock")
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lock_file = open(lock_path, "w+")
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# set access rights to a necessary minimum to prevent locking by
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# arbitrary users
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try:
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os.chmod(lock_path, stat.S_IWUSR | stat.S_IRUSR)
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except OSError:
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cls.logger.debug("Failed to set permissions on lock file")
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locked = False
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if os.name == "nt":
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handle = msvcrt.get_osfhandle(lock_file.fileno())
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flags = LOCKFILE_EXCLUSIVE_LOCK if mode == "w" else 0
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overlapped = Overlapped()
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if lock_file_ex(handle, flags, 0, 1, 0, overlapped):
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locked = True
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elif os.name == "posix":
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operation = fcntl.LOCK_EX if mode == "w" else fcntl.LOCK_SH
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# According to documentation flock() is emulated with fcntl() on
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# some platforms. fcntl() locks are not associated with an open
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# file descriptor. The same file can be locked multiple times
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# within the same process and if any fd of the file is closed,
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# all locks are released.
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# flock() does not work on NFS shares.
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try:
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fcntl.flock(lock_file.fileno(), operation)
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except OSError:
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pass
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else:
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locked = True
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if locked:
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lock = Lock(lock_file.close)
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else:
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cls.logger.debug("Locking not supported")
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lock_file.close()
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# Fallback to primitive lock which only works within one process
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# and doesn't distinguish between shared and exclusive access.
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# TODO: use readers–writer lock
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cls._lock.acquire()
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lock = Lock(cls._lock.release)
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return lock
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