2 Futz with files like a pro.
5 import sys, exceptions, os, stat, tempfile, time, binascii
7 from twisted.python import log
9 from pycryptopp.cipher.aes import AES
12 def rename(src, dst, tries=4, basedelay=0.1):
13 """ Here is a superkludge to workaround the fact that occasionally on
14 Windows some other process (e.g. an anti-virus scanner, a local search
15 engine, etc.) is looking at your file when you want to delete or move it,
16 and hence you can't. The horrible workaround is to sit and spin, trying
17 to delete it, for a short time and then give up.
19 With the default values of tries and basedelay this can block for less
22 @param tries: number of tries -- each time after the first we wait twice
23 as long as the previous wait
24 @param basedelay: how long to wait before the second try
26 for i in range(tries-1):
28 return os.rename(src, dst)
29 except EnvironmentError, le:
30 # 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.
31 log.msg("XXX KLUDGE Attempting to move file %s => %s; got %s; sleeping %s seconds" % (src, dst, le, basedelay,))
34 return os.rename(src, dst) # The last try.
36 def remove(f, tries=4, basedelay=0.1):
37 """ Here is a superkludge to workaround the fact that occasionally on
38 Windows some other process (e.g. an anti-virus scanner, a local search
39 engine, etc.) is looking at your file when you want to delete or move it,
40 and hence you can't. The horrible workaround is to sit and spin, trying
41 to delete it, for a short time and then give up.
43 With the default values of tries and basedelay this can block for less
46 @param tries: number of tries -- each time after the first we wait twice
47 as long as the previous wait
48 @param basedelay: how long to wait before the second try
51 os.chmod(f, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
54 for i in range(tries-1):
57 except EnvironmentError, le:
58 # 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.
59 if not os.path.exists(f):
61 log.msg("XXX KLUDGE Attempting to remove file %s; got %s; sleeping %s seconds" % (f, le, basedelay,))
64 return os.remove(f) # The last try.
66 class ReopenableNamedTemporaryFile:
68 This uses tempfile.mkstemp() to generate a secure temp file. It then closes
69 the file, leaving a zero-length file as a placeholder. You can get the
70 filename with ReopenableNamedTemporaryFile.name. When the
71 ReopenableNamedTemporaryFile instance is garbage collected or its shutdown()
72 method is called, it deletes the file.
74 def __init__(self, *args, **kwargs):
75 fd, self.name = tempfile.mkstemp(*args, **kwargs)
79 return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
82 return self.__repr__()
90 class EncryptedTemporaryFile:
91 # not implemented: next, readline, readlines, xreadlines, writelines
94 self.file = tempfile.TemporaryFile()
95 self.key = os.urandom(16) # AES-128
97 def _crypt(self, offset, data):
98 offset_big = offset // 16
99 offset_small = offset % 16
100 iv = binascii.unhexlify("%032x" % offset_big)
101 cipher = AES(self.key, iv=iv)
102 cipher.process("\x00"*offset_small)
103 return cipher.process(data)
111 def seek(self, offset, whence=0): # 0 = SEEK_SET
112 self.file.seek(offset, whence)
115 offset = self.file.tell()
118 def read(self, size=-1):
119 """A read must not follow a write, or vice-versa, without an intervening seek."""
120 index = self.file.tell()
121 ciphertext = self.file.read(size)
122 plaintext = self._crypt(index, ciphertext)
125 def write(self, plaintext):
126 """A read must not follow a write, or vice-versa, without an intervening seek.
127 If seeking and then writing causes a 'hole' in the file, the contents of the
128 hole are unspecified."""
129 index = self.file.tell()
130 ciphertext = self._crypt(index, plaintext)
131 self.file.write(ciphertext)
133 def truncate(self, newsize):
134 """Truncate or extend the file to 'newsize'. If it is extended, the contents after the
135 old end-of-file are unspecified. The file position after this operation is unspecified."""
136 self.file.truncate(newsize)
139 def make_dirs(dirname, mode=0777):
141 An idempotent version of os.makedirs(). If the dir already exists, do
142 nothing and return without raising an exception. If this call creates the
143 dir, return without raising an exception. If there is an error that
144 prevents creation or if the directory gets deleted after make_dirs() creates
145 it and before make_dirs() checks that it exists, raise an exception.
149 os.makedirs(dirname, mode)
153 if not os.path.isdir(dirname):
156 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...
160 A threadsafe and idempotent version of shutil.rmtree(). If the dir is
161 already gone, do nothing and return without raising an exception. If this
162 call removes the dir, return without raising an exception. If there is an
163 error that prevents deletion or if the directory gets created again after
164 rm_dir() deletes it and before rm_dir() checks that it is gone, raise an
169 os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
170 for f in os.listdir(dirname):
171 fullname = os.path.join(dirname, f)
172 if os.path.isdir(fullname):
177 except Exception, le:
178 # Ignore "No such file or directory"
179 if (not isinstance(le, OSError)) or le.args[0] != 2:
182 # Okay, now we've recursively removed everything, ignoring any "No
183 # such file or directory" errors, and collecting any other errors.
185 if os.path.exists(dirname):
189 raise OSError, "Failed to remove dir for unknown reason."
193 def remove_if_possible(f):
202 for root, dirs, files in os.walk(basedir):
204 fn = os.path.join(root, f)
205 size += os.path.getsize(fn)
209 def move_into_place(source, dest):
210 """Atomically replace a file, or as near to it as the platform allows.
211 The dest file may or may not exist."""
212 if "win32" in sys.platform.lower():
213 remove_if_possible(dest)
214 os.rename(source, dest)
216 def write_atomically(target, contents, mode="b"):
217 f = open(target+".tmp", "w"+mode)
222 move_into_place(target+".tmp", target)
224 def write(path, data, mode="wb"):
225 wf = open(path, mode)
232 rf = open(path, "rb")
238 def put_file(path, inf):
239 precondition_abspath(path)
241 # TODO: create temporary file and move into place?
242 outf = open(path, "wb")
245 data = inf.read(32768)
253 def precondition_abspath(path):
254 if not isinstance(path, unicode):
255 raise AssertionError("an abspath must be a Unicode string")
257 if sys.platform == "win32":
258 # This intentionally doesn't view absolute paths starting with a drive specification, or
259 # paths relative to the current drive, as acceptable.
260 if not path.startswith("\\\\"):
261 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
263 # This intentionally doesn't view the path '~' or paths starting with '~/' as acceptable.
264 if not os.path.isabs(path):
265 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
267 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
268 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
269 # with some simplifications.
271 _getfullpathname = None
273 from nt import _getfullpathname
277 def abspath_expanduser_unicode(path, base=None):
279 Return the absolute version of a path. If 'base' is given and 'path' is relative,
280 the path will be expanded relative to 'base'.
281 'path' must be a Unicode string. 'base', if given, must be a Unicode string
282 corresponding to an absolute path as returned by a previous call to
283 abspath_expanduser_unicode.
285 if not isinstance(path, unicode):
286 raise AssertionError("paths must be Unicode strings")
288 precondition_abspath(base)
290 path = expanduser(path)
293 # On Windows, os.path.isabs will incorrectly return True
294 # for paths without a drive letter (that are not UNC paths),
295 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
298 path = _getfullpathname(path or u".")
300 path = _getfullpathname(os.path.join(base, path))
304 if not os.path.isabs(path):
306 path = os.path.join(os.getcwdu(), path)
308 path = os.path.join(base, path)
310 # We won't hit <http://bugs.python.org/issue5827> because
311 # there is always at least one Unicode path component.
312 path = os.path.normpath(path)
314 if sys.platform == "win32":
315 path = to_windows_long_path(path)
319 def to_windows_long_path(path):
320 # '/' is normally a perfectly valid path component separator in Windows.
321 # However, when using the "\\?\" syntax it is not recognized, so we
322 # replace it with '\' here.
323 path = path.replace(u"/", u"\\")
325 # Note that other normalizations such as removing '.' and '..' should
326 # be done outside this function.
328 if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
330 elif path.startswith(u"\\\\"):
331 return u"\\\\?\\UNC\\" + path[2 :]
333 return u"\\\\?\\" + path
336 have_GetDiskFreeSpaceExW = False
337 if sys.platform == "win32":
338 from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_ulonglong, create_unicode_buffer, \
340 from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPWSTR
342 # <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683188%28v=vs.85%29.aspx>
343 GetEnvironmentVariableW = WINFUNCTYPE(
345 LPCWSTR, LPWSTR, DWORD,
347 )(("GetEnvironmentVariableW", windll.kernel32))
350 # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
351 PULARGE_INTEGER = POINTER(c_ulonglong)
353 # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
354 GetDiskFreeSpaceExW = WINFUNCTYPE(
356 LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER,
358 )(("GetDiskFreeSpaceExW", windll.kernel32))
360 have_GetDiskFreeSpaceExW = True
363 traceback.print_exc()
365 def expanduser(path):
366 # os.path.expanduser is hopelessly broken for Unicode paths on Windows (ticket #1674).
367 if sys.platform == "win32":
368 return windows_expanduser(path)
370 return os.path.expanduser(path)
372 def windows_expanduser(path):
373 if not path.startswith('~'):
376 home_dir = windows_getenv(u'USERPROFILE')
378 home_drive = windows_getenv(u'HOMEDRIVE')
379 home_path = windows_getenv(u'HOMEPATH')
380 if home_drive is None or home_path is None:
381 raise OSError("Could not find home directory: neither %USERPROFILE% nor (%HOMEDRIVE% and %HOMEPATH%) are set.")
382 home_dir = os.path.join(home_drive, home_path)
386 elif path.startswith('~/') or path.startswith('~\\'):
387 return os.path.join(home_dir, path[2 :])
391 # <https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382%28v=vs.85%29.aspx>
392 ERROR_ENVVAR_NOT_FOUND = 203
394 def windows_getenv(name):
395 # Based on <http://stackoverflow.com/questions/2608200/problems-with-umlauts-in-python-appdata-environvent-variable/2608368#2608368>,
396 # with improved error handling. Returns None if there is no enivronment variable of the given name.
397 if not isinstance(name, unicode):
398 raise AssertionError("name must be Unicode")
400 n = GetEnvironmentVariableW(name, None, 0)
401 # GetEnvironmentVariableW returns DWORD, so n cannot be negative.
403 err = get_last_error()
404 if err == ERROR_ENVVAR_NOT_FOUND:
406 raise OSError("Windows error %d attempting to read size of environment variable %r"
409 # Avoid an ambiguity between a zero-length string and an error in the return value of the
410 # call to GetEnvironmentVariableW below.
413 buf = create_unicode_buffer(u'\0'*n)
414 retval = GetEnvironmentVariableW(name, buf, n)
416 err = get_last_error()
417 if err == ERROR_ENVVAR_NOT_FOUND:
419 raise OSError("Windows error %d attempting to read environment variable %r"
422 raise OSError("Unexpected result %d (expected less than %d) from GetEnvironmentVariableW attempting to read environment variable %r"
427 def get_disk_stats(whichdir, reserved_space=0):
428 """Return disk statistics for the storage disk, in the form of a dict
429 with the following fields.
430 total: total bytes on disk
431 free_for_root: bytes actually free on disk
432 free_for_nonroot: bytes free for "a non-privileged user" [Unix] or
433 the current user [Windows]; might take into
434 account quotas depending on platform
435 used: bytes used on disk
436 avail: bytes available excluding reserved space
437 An AttributeError can occur if the OS has no API to get disk information.
438 An EnvironmentError can occur if the OS call fails.
440 whichdir is a directory on the filesystem in question -- the
441 answer is about the filesystem, not about the directory, so the
442 directory is used only to specify which filesystem.
444 reserved_space is how many bytes to subtract from the answer, so
445 you can pass how many bytes you would like to leave unused on this
446 filesystem as reserved_space.
449 if have_GetDiskFreeSpaceExW:
450 # If this is a Windows system and GetDiskFreeSpaceExW is available, use it.
451 # (This might put up an error dialog unless
452 # SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX) has been called,
453 # which we do in allmydata.windows.fixups.initialize().)
455 n_free_for_nonroot = c_ulonglong(0)
456 n_total = c_ulonglong(0)
457 n_free_for_root = c_ulonglong(0)
458 retval = GetDiskFreeSpaceExW(whichdir, byref(n_free_for_nonroot),
460 byref(n_free_for_root))
462 raise OSError("Windows error %d attempting to get disk statistics for %r"
463 % (get_last_error(), whichdir))
464 free_for_nonroot = n_free_for_nonroot.value
465 total = n_total.value
466 free_for_root = n_free_for_root.value
468 # For Unix-like systems.
469 # <http://docs.python.org/library/os.html#os.statvfs>
470 # <http://opengroup.org/onlinepubs/7990989799/xsh/fstatvfs.html>
471 # <http://opengroup.org/onlinepubs/7990989799/xsh/sysstatvfs.h.html>
472 s = os.statvfs(whichdir)
475 # statvfs(2) is a wrapper around statfs(2).
476 # statvfs.f_frsize = statfs.f_bsize :
477 # "minimum unit of allocation" (statvfs)
478 # "fundamental file system block size" (statfs)
479 # statvfs.f_bsize = statfs.f_iosize = stat.st_blocks : preferred IO size
480 # on an encrypted home directory ("FileVault"), it gets f_blocks
481 # wrong, and s.f_blocks*s.f_frsize is twice the size of my disk,
482 # but s.f_bavail*s.f_frsize is correct
484 total = s.f_frsize * s.f_blocks
485 free_for_root = s.f_frsize * s.f_bfree
486 free_for_nonroot = s.f_frsize * s.f_bavail
488 # valid for all platforms:
489 used = total - free_for_root
490 avail = max(free_for_nonroot - reserved_space, 0)
492 return { 'total': total,
493 'free_for_root': free_for_root,
494 'free_for_nonroot': free_for_nonroot,
499 def get_available_space(whichdir, reserved_space):
500 """Returns available space for share storage in bytes, or None if no
501 API to get this information is available.
503 whichdir is a directory on the filesystem in question -- the
504 answer is about the filesystem, not about the directory, so the
505 directory is used only to specify which filesystem.
507 reserved_space is how many bytes to subtract from the answer, so
508 you can pass how many bytes you would like to leave unused on this
509 filesystem as reserved_space.
512 return get_disk_stats(whichdir, reserved_space)['avail']
513 except AttributeError:
515 except EnvironmentError:
516 log.msg("OS call to get disk statistics failed")