2 Futz with files like a pro.
5 import sys, exceptions, os, stat, tempfile, time, binascii
7 if sys.platform == "win32":
8 from ctypes import WINFUNCTYPE, WinError, windll, POINTER, byref, c_ulonglong, \
9 create_unicode_buffer, get_last_error
10 from ctypes.wintypes import BOOL, DWORD, LPCWSTR, LPWSTR
12 from twisted.python import log
14 from pycryptopp.cipher.aes import AES
17 def rename(src, dst, tries=4, basedelay=0.1):
18 """ Here is a superkludge to workaround the fact that occasionally on
19 Windows some other process (e.g. an anti-virus scanner, a local search
20 engine, etc.) is looking at your file when you want to delete or move it,
21 and hence you can't. The horrible workaround is to sit and spin, trying
22 to delete it, for a short time and then give up.
24 With the default values of tries and basedelay this can block for less
27 @param tries: number of tries -- each time after the first we wait twice
28 as long as the previous wait
29 @param basedelay: how long to wait before the second try
31 for i in range(tries-1):
33 return os.rename(src, dst)
34 except EnvironmentError, le:
35 # 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.
36 log.msg("XXX KLUDGE Attempting to move file %s => %s; got %s; sleeping %s seconds" % (src, dst, le, basedelay,))
39 return os.rename(src, dst) # The last try.
41 def remove(f, tries=4, basedelay=0.1):
42 """ Here is a superkludge to workaround the fact that occasionally on
43 Windows some other process (e.g. an anti-virus scanner, a local search
44 engine, etc.) is looking at your file when you want to delete or move it,
45 and hence you can't. The horrible workaround is to sit and spin, trying
46 to delete it, for a short time and then give up.
48 With the default values of tries and basedelay this can block for less
51 @param tries: number of tries -- each time after the first we wait twice
52 as long as the previous wait
53 @param basedelay: how long to wait before the second try
56 os.chmod(f, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
59 for i in range(tries-1):
62 except EnvironmentError, le:
63 # 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.
64 if not os.path.exists(f):
66 log.msg("XXX KLUDGE Attempting to remove file %s; got %s; sleeping %s seconds" % (f, le, basedelay,))
69 return os.remove(f) # The last try.
71 class ReopenableNamedTemporaryFile:
73 This uses tempfile.mkstemp() to generate a secure temp file. It then closes
74 the file, leaving a zero-length file as a placeholder. You can get the
75 filename with ReopenableNamedTemporaryFile.name. When the
76 ReopenableNamedTemporaryFile instance is garbage collected or its shutdown()
77 method is called, it deletes the file.
79 def __init__(self, *args, **kwargs):
80 fd, self.name = tempfile.mkstemp(*args, **kwargs)
84 return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
87 return self.__repr__()
95 class EncryptedTemporaryFile:
96 # not implemented: next, readline, readlines, xreadlines, writelines
99 self.file = tempfile.TemporaryFile()
100 self.key = os.urandom(16) # AES-128
102 def _crypt(self, offset, data):
103 offset_big = offset // 16
104 offset_small = offset % 16
105 iv = binascii.unhexlify("%032x" % offset_big)
106 cipher = AES(self.key, iv=iv)
107 cipher.process("\x00"*offset_small)
108 return cipher.process(data)
116 def seek(self, offset, whence=0): # 0 = SEEK_SET
117 self.file.seek(offset, whence)
120 offset = self.file.tell()
123 def read(self, size=-1):
124 """A read must not follow a write, or vice-versa, without an intervening seek."""
125 index = self.file.tell()
126 ciphertext = self.file.read(size)
127 plaintext = self._crypt(index, ciphertext)
130 def write(self, plaintext):
131 """A read must not follow a write, or vice-versa, without an intervening seek.
132 If seeking and then writing causes a 'hole' in the file, the contents of the
133 hole are unspecified."""
134 index = self.file.tell()
135 ciphertext = self._crypt(index, plaintext)
136 self.file.write(ciphertext)
138 def truncate(self, newsize):
139 """Truncate or extend the file to 'newsize'. If it is extended, the contents after the
140 old end-of-file are unspecified. The file position after this operation is unspecified."""
141 self.file.truncate(newsize)
144 def make_dirs(dirname, mode=0777):
146 An idempotent version of os.makedirs(). If the dir already exists, do
147 nothing and return without raising an exception. If this call creates the
148 dir, return without raising an exception. If there is an error that
149 prevents creation or if the directory gets deleted after make_dirs() creates
150 it and before make_dirs() checks that it exists, raise an exception.
154 os.makedirs(dirname, mode)
158 if not os.path.isdir(dirname):
161 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...
165 A threadsafe and idempotent version of shutil.rmtree(). If the dir is
166 already gone, do nothing and return without raising an exception. If this
167 call removes the dir, return without raising an exception. If there is an
168 error that prevents deletion or if the directory gets created again after
169 rm_dir() deletes it and before rm_dir() checks that it is gone, raise an
174 os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
175 for f in os.listdir(dirname):
176 fullname = os.path.join(dirname, f)
177 if os.path.isdir(fullname):
182 except Exception, le:
183 # Ignore "No such file or directory"
184 if (not isinstance(le, OSError)) or le.args[0] != 2:
187 # Okay, now we've recursively removed everything, ignoring any "No
188 # such file or directory" errors, and collecting any other errors.
190 if os.path.exists(dirname):
194 raise OSError, "Failed to remove dir for unknown reason."
198 def remove_if_possible(f):
207 for root, dirs, files in os.walk(basedir):
209 fn = os.path.join(root, f)
210 size += os.path.getsize(fn)
214 def move_into_place(source, dest):
215 """Atomically replace a file, or as near to it as the platform allows.
216 The dest file may or may not exist."""
217 if "win32" in sys.platform.lower():
218 remove_if_possible(dest)
219 os.rename(source, dest)
221 def write_atomically(target, contents, mode="b"):
222 f = open(target+".tmp", "w"+mode)
227 move_into_place(target+".tmp", target)
229 def write(path, data, mode="wb"):
230 wf = open(path, mode)
237 rf = open(path, "rb")
243 def put_file(path, inf):
244 precondition_abspath(path)
246 # TODO: create temporary file and move into place?
247 outf = open(path, "wb")
250 data = inf.read(32768)
258 def precondition_abspath(path):
259 if not isinstance(path, unicode):
260 raise AssertionError("an abspath must be a Unicode string")
262 if sys.platform == "win32":
263 # This intentionally doesn't view absolute paths starting with a drive specification, or
264 # paths relative to the current drive, as acceptable.
265 if not path.startswith("\\\\"):
266 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
268 # This intentionally doesn't view the path '~' or paths starting with '~/' as acceptable.
269 if not os.path.isabs(path):
270 raise AssertionError("an abspath should be normalized using abspath_expanduser_unicode")
272 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
273 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
274 # with some simplifications.
276 _getfullpathname = None
278 from nt import _getfullpathname
282 def abspath_expanduser_unicode(path, base=None):
284 Return the absolute version of a path. If 'base' is given and 'path' is relative,
285 the path will be expanded relative to 'base'.
286 'path' must be a Unicode string. 'base', if given, must be a Unicode string
287 corresponding to an absolute path as returned by a previous call to
288 abspath_expanduser_unicode.
290 if not isinstance(path, unicode):
291 raise AssertionError("paths must be Unicode strings")
293 precondition_abspath(base)
295 path = expanduser(path)
298 # On Windows, os.path.isabs will incorrectly return True
299 # for paths without a drive letter (that are not UNC paths),
300 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
303 path = _getfullpathname(path or u".")
305 path = _getfullpathname(os.path.join(base, path))
309 if not os.path.isabs(path):
311 path = os.path.join(os.getcwdu(), path)
313 path = os.path.join(base, path)
315 # We won't hit <http://bugs.python.org/issue5827> because
316 # there is always at least one Unicode path component.
317 path = os.path.normpath(path)
319 if sys.platform == "win32":
320 path = to_windows_long_path(path)
324 def to_windows_long_path(path):
325 # '/' is normally a perfectly valid path component separator in Windows.
326 # However, when using the "\\?\" syntax it is not recognized, so we
327 # replace it with '\' here.
328 path = path.replace(u"/", u"\\")
330 # Note that other normalizations such as removing '.' and '..' should
331 # be done outside this function.
333 if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
335 elif path.startswith(u"\\\\"):
336 return u"\\\\?\\UNC\\" + path[2 :]
338 return u"\\\\?\\" + path
341 have_GetDiskFreeSpaceExW = False
342 if sys.platform == "win32":
343 # <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683188%28v=vs.85%29.aspx>
344 GetEnvironmentVariableW = WINFUNCTYPE(
345 DWORD, 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(
355 BOOL, LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER,
357 )(("GetDiskFreeSpaceExW", windll.kernel32))
359 have_GetDiskFreeSpaceExW = True
362 traceback.print_exc()
364 def expanduser(path):
365 # os.path.expanduser is hopelessly broken for Unicode paths on Windows (ticket #1674).
366 if sys.platform == "win32":
367 return windows_expanduser(path)
369 return os.path.expanduser(path)
371 def windows_expanduser(path):
372 if not path.startswith('~'):
375 home_dir = windows_getenv(u'USERPROFILE')
377 home_drive = windows_getenv(u'HOMEDRIVE')
378 home_path = windows_getenv(u'HOMEPATH')
379 if home_drive is None or home_path is None:
380 raise OSError("Could not find home directory: neither %USERPROFILE% nor (%HOMEDRIVE% and %HOMEPATH%) are set.")
381 home_dir = os.path.join(home_drive, home_path)
385 elif path.startswith('~/') or path.startswith('~\\'):
386 return os.path.join(home_dir, path[2 :])
390 # <https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382%28v=vs.85%29.aspx>
391 ERROR_ENVVAR_NOT_FOUND = 203
393 def windows_getenv(name):
394 # Based on <http://stackoverflow.com/questions/2608200/problems-with-umlauts-in-python-appdata-environvent-variable/2608368#2608368>,
395 # with improved error handling. Returns None if there is no enivronment variable of the given name.
396 if not isinstance(name, unicode):
397 raise AssertionError("name must be Unicode")
399 n = GetEnvironmentVariableW(name, None, 0)
400 # GetEnvironmentVariableW returns DWORD, so n cannot be negative.
402 err = get_last_error()
403 if err == ERROR_ENVVAR_NOT_FOUND:
405 raise OSError("WinError: %s\n attempting to read size of environment variable %r"
406 % (WinError(err), name))
408 # Avoid an ambiguity between a zero-length string and an error in the return value of the
409 # call to GetEnvironmentVariableW below.
412 buf = create_unicode_buffer(u'\0'*n)
413 retval = GetEnvironmentVariableW(name, buf, n)
415 err = get_last_error()
416 if err == ERROR_ENVVAR_NOT_FOUND:
418 raise OSError("WinError: %s\n attempting to read environment variable %r"
419 % (WinError(err), name))
421 raise OSError("Unexpected result %d (expected less than %d) from GetEnvironmentVariableW attempting to read environment variable %r"
426 def get_disk_stats(whichdir, reserved_space=0):
427 """Return disk statistics for the storage disk, in the form of a dict
428 with the following fields.
429 total: total bytes on disk
430 free_for_root: bytes actually free on disk
431 free_for_nonroot: bytes free for "a non-privileged user" [Unix] or
432 the current user [Windows]; might take into
433 account quotas depending on platform
434 used: bytes used on disk
435 avail: bytes available excluding reserved space
436 An AttributeError can occur if the OS has no API to get disk information.
437 An EnvironmentError can occur if the OS call fails.
439 whichdir is a directory on the filesystem in question -- the
440 answer is about the filesystem, not about the directory, so the
441 directory is used only to specify which filesystem.
443 reserved_space is how many bytes to subtract from the answer, so
444 you can pass how many bytes you would like to leave unused on this
445 filesystem as reserved_space.
448 if have_GetDiskFreeSpaceExW:
449 # If this is a Windows system and GetDiskFreeSpaceExW is available, use it.
450 # (This might put up an error dialog unless
451 # SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX) has been called,
452 # which we do in allmydata.windows.fixups.initialize().)
454 n_free_for_nonroot = c_ulonglong(0)
455 n_total = c_ulonglong(0)
456 n_free_for_root = c_ulonglong(0)
457 retval = GetDiskFreeSpaceExW(whichdir, byref(n_free_for_nonroot),
459 byref(n_free_for_root))
461 raise OSError("WinError: %s\n attempting to get disk statistics for %r"
462 % (WinError(get_last_error()), whichdir))
463 free_for_nonroot = n_free_for_nonroot.value
464 total = n_total.value
465 free_for_root = n_free_for_root.value
467 # For Unix-like systems.
468 # <http://docs.python.org/library/os.html#os.statvfs>
469 # <http://opengroup.org/onlinepubs/7990989799/xsh/fstatvfs.html>
470 # <http://opengroup.org/onlinepubs/7990989799/xsh/sysstatvfs.h.html>
471 s = os.statvfs(whichdir)
474 # statvfs(2) is a wrapper around statfs(2).
475 # statvfs.f_frsize = statfs.f_bsize :
476 # "minimum unit of allocation" (statvfs)
477 # "fundamental file system block size" (statfs)
478 # statvfs.f_bsize = statfs.f_iosize = stat.st_blocks : preferred IO size
479 # on an encrypted home directory ("FileVault"), it gets f_blocks
480 # wrong, and s.f_blocks*s.f_frsize is twice the size of my disk,
481 # but s.f_bavail*s.f_frsize is correct
483 total = s.f_frsize * s.f_blocks
484 free_for_root = s.f_frsize * s.f_bfree
485 free_for_nonroot = s.f_frsize * s.f_bavail
487 # valid for all platforms:
488 used = total - free_for_root
489 avail = max(free_for_nonroot - reserved_space, 0)
491 return { 'total': total,
492 'free_for_root': free_for_root,
493 'free_for_nonroot': free_for_nonroot,
498 def get_available_space(whichdir, reserved_space):
499 """Returns available space for share storage in bytes, or None if no
500 API to get this information is available.
502 whichdir is a directory on the filesystem in question -- the
503 answer is about the filesystem, not about the directory, so the
504 directory is used only to specify which filesystem.
506 reserved_space is how many bytes to subtract from the answer, so
507 you can pass how many bytes you would like to leave unused on this
508 filesystem as reserved_space.
511 return get_disk_stats(whichdir, reserved_space)['avail']
512 except AttributeError:
514 except EnvironmentError:
515 log.msg("OS call to get disk statistics failed")