2 Futz with files like a pro.
5 import sys, exceptions, os, stat, tempfile, time, binascii
6 from collections import namedtuple
7 from errno import ENOENT
9 from twisted.python import log
11 from pycryptopp.cipher.aes import AES
14 def rename(src, dst, tries=4, basedelay=0.1):
15 """ Here is a superkludge to workaround the fact that occasionally on
16 Windows some other process (e.g. an anti-virus scanner, a local search
17 engine, etc.) is looking at your file when you want to delete or move it,
18 and hence you can't. The horrible workaround is to sit and spin, trying
19 to delete it, for a short time and then give up.
21 With the default values of tries and basedelay this can block for less
24 @param tries: number of tries -- each time after the first we wait twice
25 as long as the previous wait
26 @param basedelay: how long to wait before the second try
28 for i in range(tries-1):
30 return os.rename(src, dst)
31 except EnvironmentError, le:
32 # XXX Tighten this to check if this is a permission denied error (possibly due to another Windows process having the file open and execute the superkludge only in this case.
33 log.msg("XXX KLUDGE Attempting to move file %s => %s; got %s; sleeping %s seconds" % (src, dst, le, basedelay,))
36 return os.rename(src, dst) # The last try.
38 def remove(f, tries=4, basedelay=0.1):
39 """ Here is a superkludge to workaround the fact that occasionally on
40 Windows some other process (e.g. an anti-virus scanner, a local search
41 engine, etc.) is looking at your file when you want to delete or move it,
42 and hence you can't. The horrible workaround is to sit and spin, trying
43 to delete it, for a short time and then give up.
45 With the default values of tries and basedelay this can block for less
48 @param tries: number of tries -- each time after the first we wait twice
49 as long as the previous wait
50 @param basedelay: how long to wait before the second try
53 os.chmod(f, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
56 for i in range(tries-1):
59 except EnvironmentError, le:
60 # XXX Tighten this to check if this is a permission denied error (possibly due to another Windows process having the file open and execute the superkludge only in this case.
61 if not os.path.exists(f):
63 log.msg("XXX KLUDGE Attempting to remove file %s; got %s; sleeping %s seconds" % (f, le, basedelay,))
66 return os.remove(f) # The last try.
68 class ReopenableNamedTemporaryFile:
70 This uses tempfile.mkstemp() to generate a secure temp file. It then closes
71 the file, leaving a zero-length file as a placeholder. You can get the
72 filename with ReopenableNamedTemporaryFile.name. When the
73 ReopenableNamedTemporaryFile instance is garbage collected or its shutdown()
74 method is called, it deletes the file.
76 def __init__(self, *args, **kwargs):
77 fd, self.name = tempfile.mkstemp(*args, **kwargs)
81 return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
84 return self.__repr__()
92 class EncryptedTemporaryFile:
93 # not implemented: next, readline, readlines, xreadlines, writelines
96 self.file = tempfile.TemporaryFile()
97 self.key = os.urandom(16) # AES-128
99 def _crypt(self, offset, data):
100 offset_big = offset // 16
101 offset_small = offset % 16
102 iv = binascii.unhexlify("%032x" % offset_big)
103 cipher = AES(self.key, iv=iv)
104 cipher.process("\x00"*offset_small)
105 return cipher.process(data)
113 def seek(self, offset, whence=0): # 0 = SEEK_SET
114 self.file.seek(offset, whence)
117 offset = self.file.tell()
120 def read(self, size=-1):
121 """A read must not follow a write, or vice-versa, without an intervening seek."""
122 index = self.file.tell()
123 ciphertext = self.file.read(size)
124 plaintext = self._crypt(index, ciphertext)
127 def write(self, plaintext):
128 """A read must not follow a write, or vice-versa, without an intervening seek.
129 If seeking and then writing causes a 'hole' in the file, the contents of the
130 hole are unspecified."""
131 index = self.file.tell()
132 ciphertext = self._crypt(index, plaintext)
133 self.file.write(ciphertext)
135 def truncate(self, newsize):
136 """Truncate or extend the file to 'newsize'. If it is extended, the contents after the
137 old end-of-file are unspecified. The file position after this operation is unspecified."""
138 self.file.truncate(newsize)
141 def make_dirs(dirname, mode=0777):
143 An idempotent version of os.makedirs(). If the dir already exists, do
144 nothing and return without raising an exception. If this call creates the
145 dir, return without raising an exception. If there is an error that
146 prevents creation or if the directory gets deleted after make_dirs() creates
147 it and before make_dirs() checks that it exists, raise an exception.
151 os.makedirs(dirname, mode)
155 if not os.path.isdir(dirname):
158 raise exceptions.IOError, "unknown error prevented creation of directory, or deleted the directory immediately after creation: %s" % dirname # careful not to construct an IOError with a 2-tuple, as that has a special meaning...
162 A threadsafe and idempotent version of shutil.rmtree(). If the dir is
163 already gone, do nothing and return without raising an exception. If this
164 call removes the dir, return without raising an exception. If there is an
165 error that prevents deletion or if the directory gets created again after
166 rm_dir() deletes it and before rm_dir() checks that it is gone, raise an
171 os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
172 for f in os.listdir(dirname):
173 fullname = os.path.join(dirname, f)
174 if os.path.isdir(fullname):
179 except Exception, le:
180 # Ignore "No such file or directory"
181 if (not isinstance(le, OSError)) or le.args[0] != 2:
184 # Okay, now we've recursively removed everything, ignoring any "No
185 # such file or directory" errors, and collecting any other errors.
187 if os.path.exists(dirname):
191 raise OSError, "Failed to remove dir for unknown reason."
195 def remove_if_possible(f):
204 for root, dirs, files in os.walk(basedir):
206 fn = os.path.join(root, f)
207 size += os.path.getsize(fn)
211 def move_into_place(source, dest):
212 """Atomically replace a file, or as near to it as the platform allows.
213 The dest file may or may not exist."""
214 if "win32" in sys.platform.lower():
215 remove_if_possible(dest)
216 os.rename(source, dest)
218 def write_atomically(target, contents, mode="b"):
219 f = open(target+".tmp", "w"+mode)
224 move_into_place(target+".tmp", target)
226 def write(path, data, mode="wb"):
227 wf = open(path, mode)
234 rf = open(path, "rb")
240 def put_file(path, inf):
241 precondition_abspath(path)
243 # TODO: create temporary file and move into place?
244 outf = open(path, "wb")
247 data = inf.read(32768)
255 def precondition_abspath(path):
256 if not isinstance(path, unicode):
257 raise AssertionError("an abspath must be a Unicode string")
259 if sys.platform == "win32":
260 # This intentionally doesn't view absolute paths starting with a drive specification, or
261 # paths relative to the current drive, as acceptable.
262 if not path.startswith("\\\\"):
263 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
265 # This intentionally doesn't view the path '~' or paths starting with '~/' as acceptable.
266 if not os.path.isabs(path):
267 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
269 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
270 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
271 # with some simplifications.
273 _getfullpathname = None
275 from nt import _getfullpathname
279 def abspath_expanduser_unicode(path, base=None):
281 Return the absolute version of a path. If 'base' is given and 'path' is relative,
282 the path will be expanded relative to 'base'.
283 'path' must be a Unicode string. 'base', if given, must be a Unicode string
284 corresponding to an absolute path as returned by a previous call to
285 abspath_expanduser_unicode.
287 if not isinstance(path, unicode):
288 raise AssertionError("paths must be Unicode strings")
290 precondition_abspath(base)
292 path = expanduser(path)
295 # On Windows, os.path.isabs will incorrectly return True
296 # for paths without a drive letter (that are not UNC paths),
297 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
300 path = _getfullpathname(path or u".")
302 path = _getfullpathname(os.path.join(base, path))
306 if not os.path.isabs(path):
308 path = os.path.join(os.getcwdu(), path)
310 path = os.path.join(base, path)
312 # We won't hit <http://bugs.python.org/issue5827> because
313 # there is always at least one Unicode path component.
314 path = os.path.normpath(path)
316 if sys.platform == "win32":
317 path = to_windows_long_path(path)
321 def to_windows_long_path(path):
322 # '/' is normally a perfectly valid path component separator in Windows.
323 # However, when using the "\\?\" syntax it is not recognized, so we
324 # replace it with '\' here.
325 path = path.replace(u"/", u"\\")
327 # Note that other normalizations such as removing '.' and '..' should
328 # be done outside this function.
330 if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
332 elif path.startswith(u"\\\\"):
333 return u"\\\\?\\UNC\\" + path[2 :]
335 return u"\\\\?\\" + path
338 have_GetDiskFreeSpaceExW = False
339 if sys.platform == "win32":
340 from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_ulonglong, create_unicode_buffer, \
342 from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPWSTR
344 # <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683188%28v=vs.85%29.aspx>
345 GetEnvironmentVariableW = WINFUNCTYPE(
347 LPCWSTR, LPWSTR, DWORD,
349 )(("GetEnvironmentVariableW", windll.kernel32))
352 # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
353 PULARGE_INTEGER = POINTER(c_ulonglong)
355 # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
356 GetDiskFreeSpaceExW = WINFUNCTYPE(
358 LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER,
360 )(("GetDiskFreeSpaceExW", windll.kernel32))
362 have_GetDiskFreeSpaceExW = True
365 traceback.print_exc()
367 def expanduser(path):
368 # os.path.expanduser is hopelessly broken for Unicode paths on Windows (ticket #1674).
369 if sys.platform == "win32":
370 return windows_expanduser(path)
372 return os.path.expanduser(path)
374 def windows_expanduser(path):
375 if not path.startswith('~'):
378 home_dir = windows_getenv(u'USERPROFILE')
380 home_drive = windows_getenv(u'HOMEDRIVE')
381 home_path = windows_getenv(u'HOMEPATH')
382 if home_drive is None or home_path is None:
383 raise OSError("Could not find home directory: neither %USERPROFILE% nor (%HOMEDRIVE% and %HOMEPATH%) are set.")
384 home_dir = os.path.join(home_drive, home_path)
388 elif path.startswith('~/') or path.startswith('~\\'):
389 return os.path.join(home_dir, path[2 :])
393 # <https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382%28v=vs.85%29.aspx>
394 ERROR_ENVVAR_NOT_FOUND = 203
396 def windows_getenv(name):
397 # Based on <http://stackoverflow.com/questions/2608200/problems-with-umlauts-in-python-appdata-environvent-variable/2608368#2608368>,
398 # with improved error handling. Returns None if there is no enivronment variable of the given name.
399 if not isinstance(name, unicode):
400 raise AssertionError("name must be Unicode")
402 n = GetEnvironmentVariableW(name, None, 0)
403 # GetEnvironmentVariableW returns DWORD, so n cannot be negative.
405 err = get_last_error()
406 if err == ERROR_ENVVAR_NOT_FOUND:
408 raise OSError("Windows error %d attempting to read size of environment variable %r"
411 # Avoid an ambiguity between a zero-length string and an error in the return value of the
412 # call to GetEnvironmentVariableW below.
415 buf = create_unicode_buffer(u'\0'*n)
416 retval = GetEnvironmentVariableW(name, buf, n)
418 err = get_last_error()
419 if err == ERROR_ENVVAR_NOT_FOUND:
421 raise OSError("Windows error %d attempting to read environment variable %r"
424 raise OSError("Unexpected result %d (expected less than %d) from GetEnvironmentVariableW attempting to read environment variable %r"
429 def get_disk_stats(whichdir, reserved_space=0):
430 """Return disk statistics for the storage disk, in the form of a dict
431 with the following fields.
432 total: total bytes on disk
433 free_for_root: bytes actually free on disk
434 free_for_nonroot: bytes free for "a non-privileged user" [Unix] or
435 the current user [Windows]; might take into
436 account quotas depending on platform
437 used: bytes used on disk
438 avail: bytes available excluding reserved space
439 An AttributeError can occur if the OS has no API to get disk information.
440 An EnvironmentError can occur if the OS call fails.
442 whichdir is a directory on the filesystem in question -- the
443 answer is about the filesystem, not about the directory, so the
444 directory is used only to specify which filesystem.
446 reserved_space is how many bytes to subtract from the answer, so
447 you can pass how many bytes you would like to leave unused on this
448 filesystem as reserved_space.
451 if have_GetDiskFreeSpaceExW:
452 # If this is a Windows system and GetDiskFreeSpaceExW is available, use it.
453 # (This might put up an error dialog unless
454 # SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX) has been called,
455 # which we do in allmydata.windows.fixups.initialize().)
457 n_free_for_nonroot = c_ulonglong(0)
458 n_total = c_ulonglong(0)
459 n_free_for_root = c_ulonglong(0)
460 retval = GetDiskFreeSpaceExW(whichdir, byref(n_free_for_nonroot),
462 byref(n_free_for_root))
464 raise OSError("Windows error %d attempting to get disk statistics for %r"
465 % (get_last_error(), whichdir))
466 free_for_nonroot = n_free_for_nonroot.value
467 total = n_total.value
468 free_for_root = n_free_for_root.value
470 # For Unix-like systems.
471 # <http://docs.python.org/library/os.html#os.statvfs>
472 # <http://opengroup.org/onlinepubs/7990989799/xsh/fstatvfs.html>
473 # <http://opengroup.org/onlinepubs/7990989799/xsh/sysstatvfs.h.html>
474 s = os.statvfs(whichdir)
477 # statvfs(2) is a wrapper around statfs(2).
478 # statvfs.f_frsize = statfs.f_bsize :
479 # "minimum unit of allocation" (statvfs)
480 # "fundamental file system block size" (statfs)
481 # statvfs.f_bsize = statfs.f_iosize = stat.st_blocks : preferred IO size
482 # on an encrypted home directory ("FileVault"), it gets f_blocks
483 # wrong, and s.f_blocks*s.f_frsize is twice the size of my disk,
484 # but s.f_bavail*s.f_frsize is correct
486 total = s.f_frsize * s.f_blocks
487 free_for_root = s.f_frsize * s.f_bfree
488 free_for_nonroot = s.f_frsize * s.f_bavail
490 # valid for all platforms:
491 used = total - free_for_root
492 avail = max(free_for_nonroot - reserved_space, 0)
494 return { 'total': total,
495 'free_for_root': free_for_root,
496 'free_for_nonroot': free_for_nonroot,
501 def get_available_space(whichdir, reserved_space):
502 """Returns available space for share storage in bytes, or None if no
503 API to get this information is available.
505 whichdir is a directory on the filesystem in question -- the
506 answer is about the filesystem, not about the directory, so the
507 directory is used only to specify which filesystem.
509 reserved_space is how many bytes to subtract from the answer, so
510 you can pass how many bytes you would like to leave unused on this
511 filesystem as reserved_space.
514 return get_disk_stats(whichdir, reserved_space)['avail']
515 except AttributeError:
517 except EnvironmentError:
518 log.msg("OS call to get disk statistics failed")
522 if sys.platform == "win32":
523 from ctypes.wintypes import BOOL, HANDLE, DWORD, LPCWSTR, LPVOID, WinError, get_last_error
525 # <http://msdn.microsoft.com/en-us/library/aa363858%28v=vs.85%29.aspx>
526 CreateFileW = WINFUNCTYPE(HANDLE, LPCWSTR, DWORD, DWORD, LPVOID, DWORD, DWORD, HANDLE) \
527 (("CreateFileW", windll.kernel32))
529 GENERIC_WRITE = 0x40000000
530 FILE_SHARE_READ = 0x00000001
531 FILE_SHARE_WRITE = 0x00000002
533 INVALID_HANDLE_VALUE = 0xFFFFFFFF
535 # <http://msdn.microsoft.com/en-us/library/aa364439%28v=vs.85%29.aspx>
536 FlushFileBuffers = WINFUNCTYPE(BOOL, HANDLE)(("FlushFileBuffers", windll.kernel32))
538 # <http://msdn.microsoft.com/en-us/library/ms724211%28v=vs.85%29.aspx>
539 CloseHandle = WINFUNCTYPE(BOOL, HANDLE)(("CloseHandle", windll.kernel32))
541 # <http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/4465cafb-f4ed-434f-89d8-c85ced6ffaa8/>
542 def flush_volume(path):
543 drive = os.path.splitdrive(os.path.realpath(path))[0]
545 hVolume = CreateFileW(u"\\\\.\\" + drive,
547 FILE_SHARE_READ | FILE_SHARE_WRITE,
553 if hVolume == INVALID_HANDLE_VALUE:
556 if FlushFileBuffers(hVolume) == 0:
561 def flush_volume(path):
566 class ConflictError(Exception):
569 class UnableToUnlinkReplacementError(Exception):
572 def reraise(wrapper):
573 _, exc, tb = sys.exc_info()
574 wrapper_exc = wrapper("%s: %s" % (exc.__class__.__name__, exc))
575 raise wrapper_exc.__class__, wrapper_exc, tb
577 if sys.platform == "win32":
578 from ctypes import WINFUNCTYPE, windll, WinError, get_last_error
579 from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPVOID
581 # <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365512%28v=vs.85%29.aspx>
582 ReplaceFileW = WINFUNCTYPE(
584 LPCWSTR, LPCWSTR, LPCWSTR, DWORD, LPVOID, LPVOID,
586 )(("ReplaceFileW", windll.kernel32))
588 REPLACEFILE_IGNORE_MERGE_ERRORS = 0x00000002
590 def rename_no_overwrite(source_path, dest_path):
591 os.rename(source_path, dest_path)
593 def replace_file(replaced_path, replacement_path, backup_path):
594 precondition_abspath(replaced_path)
595 precondition_abspath(replacement_path)
596 precondition_abspath(backup_path)
598 r = ReplaceFileW(replaced_path, replacement_path, backup_path,
599 REPLACEFILE_IGNORE_MERGE_ERRORS, None, None)
601 # The UnableToUnlinkReplacementError case does not happen on Windows;
602 # all errors should be treated as signalling a conflict.
603 err = get_last_error()
604 raise ConflictError("WinError: %s" % (WinError(err)))
606 def rename_no_overwrite(source_path, dest_path):
607 # link will fail with EEXIST if there is already something at dest_path.
608 os.link(source_path, dest_path)
610 os.unlink(source_path)
611 except EnvironmentError:
612 reraise(UnableToUnlinkReplacementError)
614 def replace_file(replaced_path, replacement_path, backup_path):
615 precondition_abspath(replaced_path)
616 precondition_abspath(replacement_path)
617 precondition_abspath(backup_path)
619 if not os.path.exists(replacement_path):
620 raise ConflictError("Replacement file not found: %r" % (replacement_path,))
623 os.rename(replaced_path, backup_path)
625 if e.errno != ENOENT:
628 rename_no_overwrite(replacement_path, replaced_path)
629 except EnvironmentError:
630 reraise(ConflictError)
632 PathInfo = namedtuple('PathInfo', 'isdir isfile islink exists size mtime ctime')
634 def get_pathinfo(path_u, now=None):
636 statinfo = os.lstat(path_u)
637 mode = statinfo.st_mode
638 return PathInfo(isdir =stat.S_ISDIR(mode),
639 isfile=stat.S_ISREG(mode),
640 islink=stat.S_ISLNK(mode),
642 size =statinfo.st_size,
643 mtime =statinfo.st_mtime,
644 ctime =statinfo.st_ctime,
647 if e.errno == ENOENT:
650 return PathInfo(isdir =False,