mirror of
https://github.com/janeczku/calibre-web
synced 2024-11-16 06:44:54 +00:00
106 lines
3.5 KiB
Python
106 lines
3.5 KiB
Python
# -*- coding: utf-8 -*-
|
|
r"""
|
|
werkzeug.posixemulation
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Provides a POSIX emulation for some features that are relevant to
|
|
web applications. The main purpose is to simplify support for
|
|
systems such as Windows NT that are not 100% POSIX compatible.
|
|
|
|
Currently this only implements a :func:`rename` function that
|
|
follows POSIX semantics. Eg: if the target file already exists it
|
|
will be replaced without asking.
|
|
|
|
This module was introduced in 0.6.1 and is not a public interface.
|
|
It might become one in later versions of Werkzeug.
|
|
|
|
:copyright: (c) 2013 by the Werkzeug Team, see AUTHORS for more details.
|
|
:license: BSD, see LICENSE for more details.
|
|
"""
|
|
import sys
|
|
import os
|
|
import errno
|
|
import time
|
|
import random
|
|
|
|
|
|
can_rename_open_file = False
|
|
if os.name == 'nt': # pragma: no cover
|
|
_rename = lambda src, dst: False
|
|
_rename_atomic = lambda src, dst: False
|
|
|
|
try:
|
|
import ctypes
|
|
|
|
_MOVEFILE_REPLACE_EXISTING = 0x1
|
|
_MOVEFILE_WRITE_THROUGH = 0x8
|
|
_MoveFileEx = ctypes.windll.kernel32.MoveFileExW
|
|
|
|
def _rename(src, dst):
|
|
if not isinstance(src, unicode):
|
|
src = unicode(src, sys.getfilesystemencoding())
|
|
if not isinstance(dst, unicode):
|
|
dst = unicode(dst, sys.getfilesystemencoding())
|
|
if _rename_atomic(src, dst):
|
|
return True
|
|
retry = 0
|
|
rv = False
|
|
while not rv and retry < 100:
|
|
rv = _MoveFileEx(src, dst, _MOVEFILE_REPLACE_EXISTING |
|
|
_MOVEFILE_WRITE_THROUGH)
|
|
if not rv:
|
|
time.sleep(0.001)
|
|
retry += 1
|
|
return rv
|
|
|
|
# new in Vista and Windows Server 2008
|
|
_CreateTransaction = ctypes.windll.ktmw32.CreateTransaction
|
|
_CommitTransaction = ctypes.windll.ktmw32.CommitTransaction
|
|
_MoveFileTransacted = ctypes.windll.kernel32.MoveFileTransactedW
|
|
_CloseHandle = ctypes.windll.kernel32.CloseHandle
|
|
can_rename_open_file = True
|
|
|
|
def _rename_atomic(src, dst):
|
|
ta = _CreateTransaction(None, 0, 0, 0, 0, 1000, 'Werkzeug rename')
|
|
if ta == -1:
|
|
return False
|
|
try:
|
|
retry = 0
|
|
rv = False
|
|
while not rv and retry < 100:
|
|
rv = _MoveFileTransacted(src, dst, None, None,
|
|
_MOVEFILE_REPLACE_EXISTING |
|
|
_MOVEFILE_WRITE_THROUGH, ta)
|
|
if rv:
|
|
rv = _CommitTransaction(ta)
|
|
break
|
|
else:
|
|
time.sleep(0.001)
|
|
retry += 1
|
|
return rv
|
|
finally:
|
|
_CloseHandle(ta)
|
|
except Exception:
|
|
pass
|
|
|
|
def rename(src, dst):
|
|
# Try atomic or pseudo-atomic rename
|
|
if _rename(src, dst):
|
|
return
|
|
# Fall back to "move away and replace"
|
|
try:
|
|
os.rename(src, dst)
|
|
except OSError as e:
|
|
if e.errno != errno.EEXIST:
|
|
raise
|
|
old = "%s-%08x" % (dst, random.randint(0, sys.maxint))
|
|
os.rename(dst, old)
|
|
os.rename(src, dst)
|
|
try:
|
|
os.unlink(old)
|
|
except Exception:
|
|
pass
|
|
else:
|
|
rename = os.rename
|
|
can_rename_open_file = True
|