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 if sys.platform == "win32":
10 from ctypes import WINFUNCTYPE, WinError, windll, POINTER, byref, c_ulonglong, \
11 create_unicode_buffer, get_last_error
12 from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPWSTR, LPVOID, HANDLE
14 from twisted.python import log
16 from pycryptopp.cipher.aes import AES
19 def rename(src, dst, tries=4, basedelay=0.1):
20 """ Here is a superkludge to workaround the fact that occasionally on
21 Windows some other process (e.g. an anti-virus scanner, a local search
22 engine, etc.) is looking at your file when you want to delete or move it,
23 and hence you can't. The horrible workaround is to sit and spin, trying
24 to delete it, for a short time and then give up.
26 With the default values of tries and basedelay this can block for less
29 @param tries: number of tries -- each time after the first we wait twice
30 as long as the previous wait
31 @param basedelay: how long to wait before the second try
33 for i in range(tries-1):
35 return os.rename(src, dst)
36 except EnvironmentError, le:
37 # 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.
38 log.msg("XXX KLUDGE Attempting to move file %s => %s; got %s; sleeping %s seconds" % (src, dst, le, basedelay,))
41 return os.rename(src, dst) # The last try.
43 def remove(f, tries=4, basedelay=0.1):
44 """ Here is a superkludge to workaround the fact that occasionally on
45 Windows some other process (e.g. an anti-virus scanner, a local search
46 engine, etc.) is looking at your file when you want to delete or move it,
47 and hence you can't. The horrible workaround is to sit and spin, trying
48 to delete it, for a short time and then give up.
50 With the default values of tries and basedelay this can block for less
53 @param tries: number of tries -- each time after the first we wait twice
54 as long as the previous wait
55 @param basedelay: how long to wait before the second try
58 os.chmod(f, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
61 for i in range(tries-1):
64 except EnvironmentError, le:
65 # 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.
66 if not os.path.exists(f):
68 log.msg("XXX KLUDGE Attempting to remove file %s; got %s; sleeping %s seconds" % (f, le, basedelay,))
71 return os.remove(f) # The last try.
73 class ReopenableNamedTemporaryFile:
75 This uses tempfile.mkstemp() to generate a secure temp file. It then closes
76 the file, leaving a zero-length file as a placeholder. You can get the
77 filename with ReopenableNamedTemporaryFile.name. When the
78 ReopenableNamedTemporaryFile instance is garbage collected or its shutdown()
79 method is called, it deletes the file.
81 def __init__(self, *args, **kwargs):
82 fd, self.name = tempfile.mkstemp(*args, **kwargs)
86 return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
89 return self.__repr__()
97 class EncryptedTemporaryFile:
98 # not implemented: next, readline, readlines, xreadlines, writelines
101 self.file = tempfile.TemporaryFile()
102 self.key = os.urandom(16) # AES-128
104 def _crypt(self, offset, data):
105 offset_big = offset // 16
106 offset_small = offset % 16
107 iv = binascii.unhexlify("%032x" % offset_big)
108 cipher = AES(self.key, iv=iv)
109 cipher.process("\x00"*offset_small)
110 return cipher.process(data)
118 def seek(self, offset, whence=0): # 0 = SEEK_SET
119 self.file.seek(offset, whence)
122 offset = self.file.tell()
125 def read(self, size=-1):
126 """A read must not follow a write, or vice-versa, without an intervening seek."""
127 index = self.file.tell()
128 ciphertext = self.file.read(size)
129 plaintext = self._crypt(index, ciphertext)
132 def write(self, plaintext):
133 """A read must not follow a write, or vice-versa, without an intervening seek.
134 If seeking and then writing causes a 'hole' in the file, the contents of the
135 hole are unspecified."""
136 index = self.file.tell()
137 ciphertext = self._crypt(index, plaintext)
138 self.file.write(ciphertext)
140 def truncate(self, newsize):
141 """Truncate or extend the file to 'newsize'. If it is extended, the contents after the
142 old end-of-file are unspecified. The file position after this operation is unspecified."""
143 self.file.truncate(newsize)
146 def make_dirs(dirname, mode=0777):
148 An idempotent version of os.makedirs(). If the dir already exists, do
149 nothing and return without raising an exception. If this call creates the
150 dir, return without raising an exception. If there is an error that
151 prevents creation or if the directory gets deleted after make_dirs() creates
152 it and before make_dirs() checks that it exists, raise an exception.
156 os.makedirs(dirname, mode)
160 if not os.path.isdir(dirname):
163 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...
167 A threadsafe and idempotent version of shutil.rmtree(). If the dir is
168 already gone, do nothing and return without raising an exception. If this
169 call removes the dir, return without raising an exception. If there is an
170 error that prevents deletion or if the directory gets created again after
171 rm_dir() deletes it and before rm_dir() checks that it is gone, raise an
176 os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
177 for f in os.listdir(dirname):
178 fullname = os.path.join(dirname, f)
179 if os.path.isdir(fullname):
184 except Exception, le:
185 # Ignore "No such file or directory"
186 if (not isinstance(le, OSError)) or le.args[0] != 2:
189 # Okay, now we've recursively removed everything, ignoring any "No
190 # such file or directory" errors, and collecting any other errors.
192 if os.path.exists(dirname):
196 raise OSError, "Failed to remove dir for unknown reason."
200 def remove_if_possible(f):
209 for root, dirs, files in os.walk(basedir):
211 fn = os.path.join(root, f)
212 size += os.path.getsize(fn)
216 def move_into_place(source, dest):
217 """Atomically replace a file, or as near to it as the platform allows.
218 The dest file may or may not exist."""
219 if "win32" in sys.platform.lower():
220 remove_if_possible(dest)
221 os.rename(source, dest)
223 def write_atomically(target, contents, mode="b"):
224 f = open(target+".tmp", "w"+mode)
229 move_into_place(target+".tmp", target)
231 def write(path, data, mode="wb"):
232 wf = open(path, mode)
239 rf = open(path, "rb")
245 def put_file(path, inf):
246 precondition_abspath(path)
248 # TODO: create temporary file and move into place?
249 outf = open(path, "wb")
252 data = inf.read(32768)
260 def precondition_abspath(path):
261 if not isinstance(path, unicode):
262 raise AssertionError("an abspath must be a Unicode string")
264 if sys.platform == "win32":
265 # This intentionally doesn't view absolute paths starting with a drive specification, or
266 # paths relative to the current drive, as acceptable.
267 if not path.startswith("\\\\"):
268 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
270 # This intentionally doesn't view the path '~' or paths starting with '~/' as acceptable.
271 if not os.path.isabs(path):
272 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
274 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
275 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
276 # with some simplifications.
278 _getfullpathname = None
280 from nt import _getfullpathname
284 def abspath_expanduser_unicode(path, base=None, long_path=True):
286 Return the absolute version of a path. If 'base' is given and 'path' is relative,
287 the path will be expanded relative to 'base'.
288 'path' must be a Unicode string. 'base', if given, must be a Unicode string
289 corresponding to an absolute path as returned by a previous call to
290 abspath_expanduser_unicode.
291 On Windows, the result will be a long path unless long_path is given as False.
293 if not isinstance(path, unicode):
294 raise AssertionError("paths must be Unicode strings")
295 if base is not None and long_path:
296 precondition_abspath(base)
298 path = expanduser(path)
301 # On Windows, os.path.isabs will incorrectly return True
302 # for paths without a drive letter (that are not UNC paths),
303 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
306 path = _getfullpathname(path or u".")
308 path = _getfullpathname(os.path.join(base, path))
312 if not os.path.isabs(path):
314 path = os.path.join(os.getcwdu(), path)
316 path = os.path.join(base, path)
318 # We won't hit <http://bugs.python.org/issue5827> because
319 # there is always at least one Unicode path component.
320 path = os.path.normpath(path)
322 if sys.platform == "win32" and long_path:
323 path = to_windows_long_path(path)
327 def to_windows_long_path(path):
328 # '/' is normally a perfectly valid path component separator in Windows.
329 # However, when using the "\\?\" syntax it is not recognized, so we
330 # replace it with '\' here.
331 path = path.replace(u"/", u"\\")
333 # Note that other normalizations such as removing '.' and '..' should
334 # be done outside this function.
336 if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
338 elif path.startswith(u"\\\\"):
339 return u"\\\\?\\UNC\\" + path[2 :]
341 return u"\\\\?\\" + path
344 have_GetDiskFreeSpaceExW = False
345 if sys.platform == "win32":
346 # <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683188%28v=vs.85%29.aspx>
347 GetEnvironmentVariableW = WINFUNCTYPE(
348 DWORD, LPCWSTR, LPWSTR, DWORD,
350 )(("GetEnvironmentVariableW", windll.kernel32))
353 # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
354 PULARGE_INTEGER = POINTER(c_ulonglong)
356 # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
357 GetDiskFreeSpaceExW = WINFUNCTYPE(
358 BOOL, 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("WinError: %s\n attempting to read size of environment variable %r"
409 % (WinError(err), name))
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("WinError: %s\n attempting to read environment variable %r"
422 % (WinError(err), name))
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("WinError: %s\n attempting to get disk statistics for %r"
465 % (WinError(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 # <http://msdn.microsoft.com/en-us/library/aa363858%28v=vs.85%29.aspx>
524 CreateFileW = WINFUNCTYPE(HANDLE, LPCWSTR, DWORD, DWORD, LPVOID, DWORD, DWORD, HANDLE) \
525 (("CreateFileW", windll.kernel32))
527 GENERIC_WRITE = 0x40000000
528 FILE_SHARE_READ = 0x00000001
529 FILE_SHARE_WRITE = 0x00000002
531 INVALID_HANDLE_VALUE = 0xFFFFFFFF
533 # <http://msdn.microsoft.com/en-us/library/aa364439%28v=vs.85%29.aspx>
534 FlushFileBuffers = WINFUNCTYPE(BOOL, HANDLE)(("FlushFileBuffers", windll.kernel32))
536 # <http://msdn.microsoft.com/en-us/library/ms724211%28v=vs.85%29.aspx>
537 CloseHandle = WINFUNCTYPE(BOOL, HANDLE)(("CloseHandle", windll.kernel32))
539 # <http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/4465cafb-f4ed-434f-89d8-c85ced6ffaa8/>
540 def flush_volume(path):
541 drive = os.path.splitdrive(os.path.realpath(path))[0]
543 hVolume = CreateFileW(u"\\\\.\\" + drive,
545 FILE_SHARE_READ | FILE_SHARE_WRITE,
551 if hVolume == INVALID_HANDLE_VALUE:
554 if FlushFileBuffers(hVolume) == 0:
559 def flush_volume(path):
564 class ConflictError(Exception):
567 class UnableToUnlinkReplacementError(Exception):
570 def reraise(wrapper):
571 _, exc, tb = sys.exc_info()
572 wrapper_exc = wrapper("%s: %s" % (exc.__class__.__name__, exc))
573 raise wrapper_exc.__class__, wrapper_exc, tb
575 if sys.platform == "win32":
576 # <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365512%28v=vs.85%29.aspx>
577 ReplaceFileW = WINFUNCTYPE(
579 LPCWSTR, LPCWSTR, LPCWSTR, DWORD, LPVOID, LPVOID,
581 )(("ReplaceFileW", windll.kernel32))
583 REPLACEFILE_IGNORE_MERGE_ERRORS = 0x00000002
585 def rename_no_overwrite(source_path, dest_path):
586 os.rename(source_path, dest_path)
588 def replace_file(replaced_path, replacement_path, backup_path):
589 precondition_abspath(replaced_path)
590 precondition_abspath(replacement_path)
591 precondition_abspath(backup_path)
593 r = ReplaceFileW(replaced_path, replacement_path, backup_path,
594 REPLACEFILE_IGNORE_MERGE_ERRORS, None, None)
596 # The UnableToUnlinkReplacementError case does not happen on Windows;
597 # all errors should be treated as signalling a conflict.
598 err = get_last_error()
599 raise ConflictError("WinError: %s" % (WinError(err)))
601 def rename_no_overwrite(source_path, dest_path):
602 # link will fail with EEXIST if there is already something at dest_path.
603 os.link(source_path, dest_path)
605 os.unlink(source_path)
606 except EnvironmentError:
607 reraise(UnableToUnlinkReplacementError)
609 def replace_file(replaced_path, replacement_path, backup_path):
610 precondition_abspath(replaced_path)
611 precondition_abspath(replacement_path)
612 precondition_abspath(backup_path)
614 if not os.path.exists(replacement_path):
615 raise ConflictError("Replacement file not found: %r" % (replacement_path,))
618 os.rename(replaced_path, backup_path)
620 if e.errno != ENOENT:
623 rename_no_overwrite(replacement_path, replaced_path)
624 except EnvironmentError:
625 reraise(ConflictError)
627 PathInfo = namedtuple('PathInfo', 'isdir isfile islink exists size mtime ctime')
629 def get_pathinfo(path_u, now=None):
631 statinfo = os.lstat(path_u)
632 mode = statinfo.st_mode
633 return PathInfo(isdir =stat.S_ISDIR(mode),
634 isfile=stat.S_ISREG(mode),
635 islink=stat.S_ISLNK(mode),
637 size =statinfo.st_size,
638 mtime =statinfo.st_mtime,
639 ctime =statinfo.st_ctime,
642 if e.errno == ENOENT:
645 return PathInfo(isdir =False,