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  • Committer: Andrew Bennetts
  • Date: 2008-10-30 01:05:59 UTC
  • mto: This revision was merged to the branch mainline in revision 3813.
  • Revision ID: andrew.bennetts@canonical.com-20081030010559-tumoefnsmhg4snxo
Add contrib/bzr_ssh_path_limiter.

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1
 
# Copyright (C) 2005-2010 Canonical Ltd
 
1
# Copyright (C) 2005, 2006, 2007, 2008 Canonical Ltd
2
2
#
3
3
# This program is free software; you can redistribute it and/or modify
4
4
# it under the terms of the GNU General Public License as published by
12
12
#
13
13
# You should have received a copy of the GNU General Public License
14
14
# along with this program; if not, write to the Free Software
15
 
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
15
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
16
16
 
17
17
 
18
18
"""Locking using OS file locks or file existence.
35
35
"""
36
36
 
37
37
import errno
38
 
import os
39
38
import sys
40
 
import warnings
41
39
 
42
40
from bzrlib import (
43
 
    debug,
44
41
    errors,
45
42
    osutils,
46
43
    trace,
47
44
    )
48
 
from bzrlib.hooks import HookPoint, Hooks
 
45
from bzrlib.hooks import Hooks
49
46
 
50
47
 
51
48
class LockHooks(Hooks):
52
49
 
53
50
    def __init__(self):
54
51
        Hooks.__init__(self)
55
 
        self.create_hook(HookPoint('lock_acquired',
56
 
            "Called with a bzrlib.lock.LockResult when a physical lock is "
57
 
            "acquired.", (1, 8), None))
58
 
        self.create_hook(HookPoint('lock_released',
59
 
            "Called with a bzrlib.lock.LockResult when a physical lock is "
60
 
            "released.", (1, 8), None))
61
 
        self.create_hook(HookPoint('lock_broken',
62
 
            "Called with a bzrlib.lock.LockResult when a physical lock is "
63
 
            "broken.", (1, 15), None))
 
52
 
 
53
        # added in 1.8; called with a LockResult when a physical lock is
 
54
        # acquired
 
55
        self['lock_acquired'] = []
 
56
 
 
57
        # added in 1.8; called with a LockResult when a physical lock is
 
58
        # acquired
 
59
        self['lock_released'] = []
64
60
 
65
61
 
66
62
class Lock(object):
83
79
    def __eq__(self, other):
84
80
        return self.lock_url == other.lock_url and self.details == other.details
85
81
 
86
 
    def __repr__(self):
87
 
        return '%s(%s, %s)' % (self.__class__.__name__,
88
 
                             self.lock_url, self.details)
89
 
 
90
 
 
91
 
class LogicalLockResult(object):
92
 
    """The result of a lock_read/lock_write/lock_tree_write call on lockables.
93
 
 
94
 
    :ivar unlock: A callable which will unlock the lock.
95
 
    """
96
 
 
97
 
    def __init__(self, unlock):
98
 
        self.unlock = unlock
99
 
 
100
 
    def __repr__(self):
101
 
        return "LogicalLockResult(%s)" % (self.unlock)
102
 
 
103
 
 
104
 
 
105
 
def cant_unlock_not_held(locked_object):
106
 
    """An attempt to unlock failed because the object was not locked.
107
 
 
108
 
    This provides a policy point from which we can generate either a warning 
109
 
    or an exception.
110
 
    """
111
 
    # This is typically masking some other error and called from a finally
112
 
    # block, so it's useful to have the option not to generate a new error
113
 
    # here.  You can use -Werror to make it fatal.  It should possibly also
114
 
    # raise LockNotHeld.
115
 
    if 'unlock' in debug.debug_flags:
116
 
        warnings.warn("%r is already unlocked" % (locked_object,),
117
 
            stacklevel=3)
118
 
    else:
119
 
        raise errors.LockNotHeld(locked_object)
120
 
 
121
82
 
122
83
try:
123
84
    import fcntl
130
91
if sys.platform == 'win32':
131
92
    import msvcrt
132
93
    try:
133
 
        import win32file, pywintypes, winerror
 
94
        import win32con, win32file, pywintypes, winerror
134
95
        have_pywin32 = True
135
96
    except ImportError:
136
97
        pass
185
146
 
186
147
 
187
148
if have_fcntl:
 
149
    LOCK_SH = fcntl.LOCK_SH
 
150
    LOCK_NB = fcntl.LOCK_NB
 
151
    lock_EX = fcntl.LOCK_EX
 
152
 
188
153
 
189
154
    class _fcntl_FileLock(_OSLock):
190
155
 
204
169
            if self.filename in _fcntl_WriteLock._open_locks:
205
170
                self._clear_f()
206
171
                raise errors.LockContention(self.filename)
207
 
            if self.filename in _fcntl_ReadLock._open_locks:
208
 
                if 'strict_locks' in debug.debug_flags:
209
 
                    self._clear_f()
210
 
                    raise errors.LockContention(self.filename)
211
 
                else:
212
 
                    trace.mutter('Write lock taken w/ an open read lock on: %s'
213
 
                                 % (self.filename,))
214
172
 
215
173
            self._open(self.filename, 'rb+')
216
174
            # reserve a slot for this lock - even if the lockf call fails,
217
 
            # at this point unlock() will be called, because self.f is set.
 
175
            # at thisi point unlock() will be called, because self.f is set.
218
176
            # TODO: make this fully threadsafe, if we decide we care.
219
177
            _fcntl_WriteLock._open_locks.add(self.filename)
220
178
            try:
227
185
                    self.unlock()
228
186
                # we should be more precise about whats a locking
229
187
                # error and whats a random-other error
230
 
                raise errors.LockContention(self.filename, e)
 
188
                raise errors.LockContention(e)
231
189
 
232
190
        def unlock(self):
233
191
            _fcntl_WriteLock._open_locks.remove(self.filename)
241
199
        def __init__(self, filename):
242
200
            super(_fcntl_ReadLock, self).__init__()
243
201
            self.filename = osutils.realpath(filename)
244
 
            if self.filename in _fcntl_WriteLock._open_locks:
245
 
                if 'strict_locks' in debug.debug_flags:
246
 
                    # We raise before calling _open so we don't need to
247
 
                    # _clear_f
248
 
                    raise errors.LockContention(self.filename)
249
 
                else:
250
 
                    trace.mutter('Read lock taken w/ an open write lock on: %s'
251
 
                                 % (self.filename,))
252
202
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
253
203
            _fcntl_ReadLock._open_locks[self.filename] += 1
254
204
            self._open(filename, 'rb')
259
209
            except IOError, e:
260
210
                # we should be more precise about whats a locking
261
211
                # error and whats a random-other error
262
 
                raise errors.LockContention(self.filename, e)
 
212
                raise errors.LockContention(e)
263
213
 
264
214
        def unlock(self):
265
215
            count = _fcntl_ReadLock._open_locks[self.filename]
327
277
                fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
328
278
            except IOError, e:
329
279
                # TODO: Raise a more specific error based on the type of error
330
 
                raise errors.LockContention(self.filename, e)
 
280
                raise errors.LockContention(e)
331
281
            _fcntl_WriteLock._open_locks.add(self.filename)
332
282
 
333
283
            self.f = new_f
349
299
 
350
300
 
351
301
if have_pywin32 and sys.platform == 'win32':
352
 
    if os.path.supports_unicode_filenames:
353
 
        # for Windows NT/2K/XP/etc
354
 
        win32file_CreateFile = win32file.CreateFileW
355
 
    else:
356
 
        # for Windows 98
357
 
        win32file_CreateFile = win32file.CreateFile
 
302
    LOCK_SH = 0 # the default
 
303
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
 
304
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
 
305
 
358
306
 
359
307
    class _w32c_FileLock(_OSLock):
360
308
 
361
 
        def _open(self, filename, access, share, cflags, pymode):
362
 
            self.filename = osutils.realpath(filename)
 
309
        def _lock(self, filename, openmode, lockmode):
 
310
            self._open(filename, openmode)
 
311
 
 
312
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
313
            overlapped = pywintypes.OVERLAPPED()
363
314
            try:
364
 
                self._handle = win32file_CreateFile(filename, access, share,
365
 
                    None, win32file.OPEN_ALWAYS,
366
 
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
 
315
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
 
316
                                     overlapped)
367
317
            except pywintypes.error, e:
368
 
                if e.args[0] == winerror.ERROR_ACCESS_DENIED:
369
 
                    raise errors.LockFailed(filename, e)
370
 
                if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
371
 
                    raise errors.LockContention(filename, e)
 
318
                self._clear_f()
 
319
                if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
 
320
                    raise errors.LockContention(filename)
 
321
                ## import pdb; pdb.set_trace()
372
322
                raise
373
 
            fd = win32file._open_osfhandle(self._handle, cflags)
374
 
            self.f = os.fdopen(fd, pymode)
375
 
            return self.f
 
323
            except Exception, e:
 
324
                self._clear_f()
 
325
                raise errors.LockContention(e)
376
326
 
377
327
        def unlock(self):
378
 
            self._clear_f()
379
 
            self._handle = None
 
328
            overlapped = pywintypes.OVERLAPPED()
 
329
            try:
 
330
                win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
 
331
                self._clear_f()
 
332
            except Exception, e:
 
333
                raise errors.LockContention(e)
380
334
 
381
335
 
382
336
    class _w32c_ReadLock(_w32c_FileLock):
383
337
        def __init__(self, filename):
384
338
            super(_w32c_ReadLock, self).__init__()
385
 
            self._open(filename, win32file.GENERIC_READ,
386
 
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
 
339
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
387
340
 
388
341
        def temporary_write_lock(self):
389
342
            """Try to grab a write lock on the file.
408
361
    class _w32c_WriteLock(_w32c_FileLock):
409
362
        def __init__(self, filename):
410
363
            super(_w32c_WriteLock, self).__init__()
411
 
            self._open(filename,
412
 
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
413
 
                os.O_RDWR, "rb+")
 
364
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
414
365
 
415
366
        def restore_read_lock(self):
416
367
            """Restore the original ReadLock."""
424
375
 
425
376
 
426
377
if have_ctypes_win32:
427
 
    from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
428
 
    LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
429
 
    HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
430
 
    if os.path.supports_unicode_filenames:
431
 
        _function_name = "CreateFileW"
432
 
        LPTSTR = LPCWSTR
433
 
    else:
434
 
        _function_name = "CreateFileA"
435
 
        class LPTSTR(LPCSTR):
436
 
            def __new__(cls, obj):
437
 
                return LPCSTR.__new__(cls, obj.encode("mbcs"))
438
 
 
439
 
    # CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
440
 
    _CreateFile = ctypes.WINFUNCTYPE(
441
 
            HANDLE,                # return value
442
 
            LPTSTR,                # lpFileName
443
 
            DWORD,                 # dwDesiredAccess
444
 
            DWORD,                 # dwShareMode
445
 
            LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
446
 
            DWORD,                 # dwCreationDisposition
447
 
            DWORD,                 # dwFlagsAndAttributes
448
 
            HANDLE                 # hTemplateFile
449
 
        )((_function_name, ctypes.windll.kernel32))
450
 
 
451
 
    INVALID_HANDLE_VALUE = -1
452
 
 
453
 
    GENERIC_READ = 0x80000000
454
 
    GENERIC_WRITE = 0x40000000
455
 
    FILE_SHARE_READ = 1
456
 
    OPEN_ALWAYS = 4
457
 
    FILE_ATTRIBUTE_NORMAL = 128
458
 
 
459
 
    ERROR_ACCESS_DENIED = 5
460
 
    ERROR_SHARING_VIOLATION = 32
 
378
    # These constants were copied from the win32con.py module.
 
379
    LOCKFILE_FAIL_IMMEDIATELY = 1
 
380
    LOCKFILE_EXCLUSIVE_LOCK = 2
 
381
    # Constant taken from winerror.py module
 
382
    ERROR_LOCK_VIOLATION = 33
 
383
 
 
384
    LOCK_SH = 0
 
385
    LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
 
386
    LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
 
387
    _LockFileEx = ctypes.windll.kernel32.LockFileEx
 
388
    _UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
 
389
    _GetLastError = ctypes.windll.kernel32.GetLastError
 
390
 
 
391
    ### Define the OVERLAPPED structure.
 
392
    #   http://msdn2.microsoft.com/en-us/library/ms684342.aspx
 
393
    # typedef struct _OVERLAPPED {
 
394
    #   ULONG_PTR Internal;
 
395
    #   ULONG_PTR InternalHigh;
 
396
    #   union {
 
397
    #     struct {
 
398
    #       DWORD Offset;
 
399
    #       DWORD OffsetHigh;
 
400
    #     };
 
401
    #     PVOID Pointer;
 
402
    #   };
 
403
    #   HANDLE hEvent;
 
404
    # } OVERLAPPED,
 
405
 
 
406
    class _inner_struct(ctypes.Structure):
 
407
        _fields_ = [('Offset', ctypes.c_uint), # DWORD
 
408
                    ('OffsetHigh', ctypes.c_uint), # DWORD
 
409
                   ]
 
410
 
 
411
    class _inner_union(ctypes.Union):
 
412
        _fields_  = [('anon_struct', _inner_struct), # struct
 
413
                     ('Pointer', ctypes.c_void_p), # PVOID
 
414
                    ]
 
415
 
 
416
    class OVERLAPPED(ctypes.Structure):
 
417
        _fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
 
418
                    ('InternalHigh', ctypes.c_void_p), # ULONG_PTR
 
419
                    ('_inner_union', _inner_union),
 
420
                    ('hEvent', ctypes.c_void_p), # HANDLE
 
421
                   ]
461
422
 
462
423
    class _ctypes_FileLock(_OSLock):
463
424
 
464
 
        def _open(self, filename, access, share, cflags, pymode):
465
 
            self.filename = osutils.realpath(filename)
466
 
            handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
467
 
                FILE_ATTRIBUTE_NORMAL, 0)
468
 
            if handle in (INVALID_HANDLE_VALUE, 0):
469
 
                e = ctypes.WinError()
470
 
                if e.args[0] == ERROR_ACCESS_DENIED:
471
 
                    raise errors.LockFailed(filename, e)
472
 
                if e.args[0] == ERROR_SHARING_VIOLATION:
473
 
                    raise errors.LockContention(filename, e)
474
 
                raise e
475
 
            fd = msvcrt.open_osfhandle(handle, cflags)
476
 
            self.f = os.fdopen(fd, pymode)
477
 
            return self.f
 
425
        def _lock(self, filename, openmode, lockmode):
 
426
            self._open(filename, openmode)
 
427
 
 
428
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
429
            overlapped = OVERLAPPED()
 
430
            result = _LockFileEx(self.hfile, # HANDLE hFile
 
431
                                 lockmode,   # DWORD dwFlags
 
432
                                 0,          # DWORD dwReserved
 
433
                                 0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
434
                                 0x00000000, # DWORD nNumberOfBytesToLockHigh
 
435
                                 ctypes.byref(overlapped), # lpOverlapped
 
436
                                )
 
437
            if result == 0:
 
438
                self._clear_f()
 
439
                last_err = _GetLastError()
 
440
                if last_err in (ERROR_LOCK_VIOLATION,):
 
441
                    raise errors.LockContention(filename)
 
442
                raise errors.LockContention('Unknown locking error: %s'
 
443
                                            % (last_err,))
478
444
 
479
445
        def unlock(self):
 
446
            overlapped = OVERLAPPED()
 
447
            result = _UnlockFileEx(self.hfile, # HANDLE hFile
 
448
                                   0,          # DWORD dwReserved
 
449
                                   0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
450
                                   0x00000000, # DWORD nNumberOfBytesToLockHigh
 
451
                                   ctypes.byref(overlapped), # lpOverlapped
 
452
                                  )
480
453
            self._clear_f()
 
454
            if result == 0:
 
455
                self._clear_f()
 
456
                last_err = _GetLastError()
 
457
                raise errors.LockContention('Unknown unlocking error: %s'
 
458
                                            % (last_err,))
481
459
 
482
460
 
483
461
    class _ctypes_ReadLock(_ctypes_FileLock):
484
462
        def __init__(self, filename):
485
463
            super(_ctypes_ReadLock, self).__init__()
486
 
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
487
 
                "rb")
 
464
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
488
465
 
489
466
        def temporary_write_lock(self):
490
467
            """Try to grab a write lock on the file.
508
485
    class _ctypes_WriteLock(_ctypes_FileLock):
509
486
        def __init__(self, filename):
510
487
            super(_ctypes_WriteLock, self).__init__()
511
 
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
512
 
                "rb+")
 
488
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
513
489
 
514
490
        def restore_read_lock(self):
515
491
            """Restore the original ReadLock."""
532
508
# We default to using the first available lock class.
533
509
_lock_type, WriteLock, ReadLock = _lock_classes[0]
534
510
 
535
 
 
536
 
class _RelockDebugMixin(object):
537
 
    """Mixin support for -Drelock flag.
538
 
 
539
 
    Add this as a base class then call self._note_lock with 'r' or 'w' when
540
 
    acquiring a read- or write-lock.  If this object was previously locked (and
541
 
    locked the same way), and -Drelock is set, then this will trace.note a
542
 
    message about it.
543
 
    """
544
 
    
545
 
    _prev_lock = None
546
 
 
547
 
    def _note_lock(self, lock_type):
548
 
        if 'relock' in debug.debug_flags and self._prev_lock == lock_type:
549
 
            if lock_type == 'r':
550
 
                type_name = 'read'
551
 
            else:
552
 
                type_name = 'write'
553
 
            trace.note('%r was %s locked again', self, type_name)
554
 
        self._prev_lock = lock_type
555