1
# Copyright (C) 2005, 2006, 2007 Canonical Ltd
3
# This program is free software; you can redistribute it and/or modify
4
# it under the terms of the GNU General Public License as published by
5
# the Free Software Foundation; either version 2 of the License, or
6
# (at your option) any later version.
8
# This program is distributed in the hope that it will be useful,
9
# but WITHOUT ANY WARRANTY; without even the implied warranty of
10
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11
# GNU General Public License for more details.
13
# You should have received a copy of the GNU General Public License
14
# along with this program; if not, write to the Free Software
15
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
"""Locking using OS file locks or file existence.
20
Note: This method of locking is generally deprecated in favour of LockDir, but
21
is used to lock local WorkingTrees, and by some old formats. It's accessed
22
through Transport.lock_read(), etc.
24
This module causes two methods, lock() and unlock() to be defined in
25
any way that works on the current platform.
27
It is not specified whether these locks are reentrant (i.e. can be
28
taken repeatedly by a single process) or whether they exclude
29
different threads in a single process. That reentrancy is provided by
32
This defines two classes: ReadLock and WriteLock, which can be
33
implemented in different ways on different platforms. Both have an
47
class _base_Lock(object):
53
def _open(self, filename, filemode):
54
self.filename = osutils.realpath(filename)
56
self.f = open(self.filename, filemode)
59
if e.errno in (errno.EACCES, errno.EPERM):
60
raise errors.ReadOnlyLockError(self.filename, str(e))
61
if e.errno != errno.ENOENT:
64
# maybe this is an old branch (before may 2005)
65
trace.mutter("trying to create missing lock %r", self.filename)
67
self.f = open(self.filename, 'wb+')
71
"""Clear the self.f attribute cleanly."""
78
from warnings import warn
79
warn("lock on %r not released" % self.f)
83
raise NotImplementedError()
92
import win32con, win32file, pywintypes, winerror, msvcrt
107
LOCK_SH = fcntl.LOCK_SH
108
LOCK_NB = fcntl.LOCK_NB
109
lock_EX = fcntl.LOCK_EX
112
class _fcntl_FileLock(_base_Lock):
115
fcntl.lockf(self.f, fcntl.LOCK_UN)
119
class _fcntl_WriteLock(_fcntl_FileLock):
123
def __init__(self, filename):
124
# standard IO errors get exposed directly.
125
super(_fcntl_WriteLock, self).__init__()
126
self._open(filename, 'rb+')
127
if self.filename in self.open_locks:
129
raise errors.LockContention(self.filename)
130
# reserve a slot for this lock - even if the lockf call fails,
131
# at thisi point unlock() will be called, because self.f is set.
132
# TODO: make this fully threadsafe, if we decide we care.
133
self.open_locks[self.filename] = self.filename
135
# LOCK_NB will cause IOError to be raised if we can't grab a
137
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
139
if e.errno in (errno.EAGAIN, errno.EACCES):
140
# We couldn't grab the lock
142
# we should be more precise about whats a locking
143
# error and whats a random-other error
144
raise errors.LockError(e)
147
del self.open_locks[self.filename]
151
class _fcntl_ReadLock(_fcntl_FileLock):
155
def __init__(self, filename):
156
super(_fcntl_ReadLock, self).__init__()
157
self._open(filename, 'rb')
159
# LOCK_NB will cause IOError to be raised if we can't grab a
161
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
163
# we should be more precise about whats a locking
164
# error and whats a random-other error
165
raise errors.LockError(e)
171
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
174
if have_pywin32 and sys.platform == 'win32':
175
LOCK_SH = 0 # the default
176
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
177
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
180
class _w32c_FileLock(_base_Lock):
182
def _lock(self, filename, openmode, lockmode):
183
self._open(filename, openmode)
185
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
186
overlapped = pywintypes.OVERLAPPED()
188
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
190
except pywintypes.error, e:
192
if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
193
raise errors.LockContention(filename)
194
## import pdb; pdb.set_trace()
198
raise errors.LockError(e)
201
overlapped = pywintypes.OVERLAPPED()
203
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
206
raise errors.LockError(e)
209
class _w32c_ReadLock(_w32c_FileLock):
210
def __init__(self, filename):
211
super(_w32c_ReadLock, self).__init__()
212
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
215
class _w32c_WriteLock(_w32c_FileLock):
216
def __init__(self, filename):
217
super(_w32c_WriteLock, self).__init__()
218
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
221
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
224
if have_ctypes and sys.platform == 'win32':
225
# These constants were copied from the win32con.py module.
226
LOCKFILE_FAIL_IMMEDIATELY = 1
227
LOCKFILE_EXCLUSIVE_LOCK = 2
228
# Constant taken from winerror.py module
229
ERROR_LOCK_VIOLATION = 33
232
LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
233
LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
234
_LockFileEx = ctypes.windll.kernel32.LockFileEx
235
_UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
236
_GetLastError = ctypes.windll.kernel32.GetLastError
238
### Define the OVERLAPPED structure.
239
# http://msdn2.microsoft.com/en-us/library/ms684342.aspx
240
# typedef struct _OVERLAPPED {
241
# ULONG_PTR Internal;
242
# ULONG_PTR InternalHigh;
253
class _inner_struct(ctypes.Structure):
254
_fields_ = [('Offset', ctypes.c_uint), # DWORD
255
('OffsetHigh', ctypes.c_uint), # DWORD
258
class _inner_union(ctypes.Union):
259
_fields_ = [('anon_struct', _inner_struct), # struct
260
('Pointer', ctypes.c_void_p), # PVOID
263
class OVERLAPPED(ctypes.Structure):
264
_fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
265
('InternalHigh', ctypes.c_void_p), # ULONG_PTR
266
('_inner_union', _inner_union),
267
('hEvent', ctypes.c_void_p), # HANDLE
270
class _ctypes_FileLock(_base_Lock):
272
def _lock(self, filename, openmode, lockmode):
273
self._open(filename, openmode)
275
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
276
overlapped = OVERLAPPED()
277
p_overlapped = ctypes.pointer(overlapped)
278
result = _LockFileEx(self.hfile, # HANDLE hFile
279
lockmode, # DWORD dwFlags
280
0, # DWORD dwReserved
281
0x7fffffff, # DWORD nNumberOfBytesToLockLow
282
0x00000000, # DWORD nNumberOfBytesToLockHigh
283
p_overlapped, # lpOverlapped
287
last_err = _GetLastError()
288
if last_err in (ERROR_LOCK_VIOLATION,):
289
raise errors.LockContention(filename)
290
raise errors.LockError('Unknown locking error: %s'
294
overlapped = OVERLAPPED()
295
p_overlapped = ctypes.pointer(overlapped)
296
result = _UnlockFileEx(self.hfile, # HANDLE hFile
297
0, # DWORD dwReserved
298
0x7fffffff, # DWORD nNumberOfBytesToLockLow
299
0x00000000, # DWORD nNumberOfBytesToLockHigh
300
p_overlapped, # lpOverlapped
305
last_err = _GetLastError()
306
raise errors.LockError('Unknown unlocking error: %s'
310
class _ctypes_ReadLock(_ctypes_FileLock):
311
def __init__(self, filename):
312
super(_ctypes_ReadLock, self).__init__()
313
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
316
class _ctypes_WriteLock(_ctypes_FileLock):
317
def __init__(self, filename):
318
super(_ctypes_WriteLock, self).__init__()
319
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
322
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
325
if len(_lock_classes) == 0:
326
raise NotImplementedError(
327
"We must have one of fcntl, pywin32, or ctypes available"
328
" to support OS locking."
332
# We default to using the first available lock class.
333
_lock_type, WriteLock, ReadLock = _lock_classes[0]
added
removed
bzrlib/lock.py
