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 NamedTemporaryDirectory:
92 This calls tempfile.mkdtemp(), stores the name of the dir in
93 self.name, and rmrf's the dir when it gets garbage collected or
96 def __init__(self, cleanup=True, *args, **kwargs):
97 """ If cleanup, then the directory will be rmrf'ed when the object is shutdown. """
98 self.cleanup = cleanup
99 self.name = tempfile.mkdtemp(*args, **kwargs)
102 return "<%s instance at %x %s>" % (self.__class__.__name__, id(self), self.name)
105 return self.__repr__()
112 traceback.print_exc()
115 if self.cleanup and hasattr(self, 'name'):
118 class EncryptedTemporaryFile:
119 # not implemented: next, readline, readlines, xreadlines, writelines
122 self.file = tempfile.TemporaryFile()
123 self.key = os.urandom(16) # AES-128
125 def _crypt(self, offset, data):
126 offset_big = offset // 16
127 offset_small = offset % 16
128 iv = binascii.unhexlify("%032x" % offset_big)
129 cipher = AES(self.key, iv=iv)
130 cipher.process("\x00"*offset_small)
131 return cipher.process(data)
139 def seek(self, offset, whence=0): # 0 = SEEK_SET
140 self.file.seek(offset, whence)
143 offset = self.file.tell()
146 def read(self, size=-1):
147 """A read must not follow a write, or vice-versa, without an intervening seek."""
148 index = self.file.tell()
149 ciphertext = self.file.read(size)
150 plaintext = self._crypt(index, ciphertext)
153 def write(self, plaintext):
154 """A read must not follow a write, or vice-versa, without an intervening seek.
155 If seeking and then writing causes a 'hole' in the file, the contents of the
156 hole are unspecified."""
157 index = self.file.tell()
158 ciphertext = self._crypt(index, plaintext)
159 self.file.write(ciphertext)
161 def truncate(self, newsize):
162 """Truncate or extend the file to 'newsize'. If it is extended, the contents after the
163 old end-of-file are unspecified. The file position after this operation is unspecified."""
164 self.file.truncate(newsize)
167 def make_dirs(dirname, mode=0777):
169 An idempotent version of os.makedirs(). If the dir already exists, do
170 nothing and return without raising an exception. If this call creates the
171 dir, return without raising an exception. If there is an error that
172 prevents creation or if the directory gets deleted after make_dirs() creates
173 it and before make_dirs() checks that it exists, raise an exception.
177 os.makedirs(dirname, mode)
181 if not os.path.isdir(dirname):
184 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...
188 A threadsafe and idempotent version of shutil.rmtree(). If the dir is
189 already gone, do nothing and return without raising an exception. If this
190 call removes the dir, return without raising an exception. If there is an
191 error that prevents deletion or if the directory gets created again after
192 rm_dir() deletes it and before rm_dir() checks that it is gone, raise an
197 os.chmod(dirname, stat.S_IWRITE | stat.S_IEXEC | stat.S_IREAD)
198 for f in os.listdir(dirname):
199 fullname = os.path.join(dirname, f)
200 if os.path.isdir(fullname):
205 except Exception, le:
206 # Ignore "No such file or directory"
207 if (not isinstance(le, OSError)) or le.args[0] != 2:
210 # Okay, now we've recursively removed everything, ignoring any "No
211 # such file or directory" errors, and collecting any other errors.
213 if os.path.exists(dirname):
217 raise OSError, "Failed to remove dir for unknown reason."
221 def remove_if_possible(f):
230 for root, dirs, files in os.walk(basedir):
232 fn = os.path.join(root, f)
233 size += os.path.getsize(fn)
237 def move_into_place(source, dest):
238 """Atomically replace a file, or as near to it as the platform allows.
239 The dest file may or may not exist."""
240 if "win32" in sys.platform.lower():
241 remove_if_possible(dest)
242 os.rename(source, dest)
244 def write_atomically(target, contents, mode="b"):
245 f = open(target+".tmp", "w"+mode)
250 move_into_place(target+".tmp", target)
252 def write(path, data, mode="wb"):
253 wf = open(path, mode)
260 rf = open(path, "rb")
266 def put_file(pathname, inf):
267 # TODO: create temporary file and move into place?
268 outf = open(os.path.expanduser(pathname), "wb")
271 data = inf.read(32768)
279 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
280 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
281 # with some simplifications.
283 _getfullpathname = None
285 from nt import _getfullpathname
289 def abspath_expanduser_unicode(path):
290 """Return the absolute version of a path."""
291 assert isinstance(path, unicode), path
293 path = os.path.expanduser(path)
296 # On Windows, os.path.isabs will return True for paths without a drive letter,
297 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
299 path = _getfullpathname(path or u".")
303 if not os.path.isabs(path):
304 path = os.path.join(os.getcwdu(), path)
306 # We won't hit <http://bugs.python.org/issue5827> because
307 # there is always at least one Unicode path component.
308 path = os.path.normpath(path)
310 if sys.platform == "win32":
311 path = to_windows_long_path(path)
315 def to_windows_long_path(path):
316 # '/' is normally a perfectly valid path component separator in Windows.
317 # However, when using the "\\?\" syntax it is not recognized, so we
318 # replace it with '\' here.
319 path = path.replace(u"/", u"\\")
321 # Note that other normalizations such as removing '.' and '..' should
322 # be done outside this function.
324 if path.startswith(u"\\\\?\\") or path.startswith(u"\\\\.\\"):
326 elif path.startswith(u"\\\\"):
327 return u"\\\\?\\UNC\\" + path[2 :]
329 return u"\\\\?\\" + path
332 have_GetDiskFreeSpaceExW = False
333 if sys.platform == "win32":
335 from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_ulonglong
336 from ctypes.wintypes import BOOL, DWORD, LPCWSTR
338 # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
339 PULARGE_INTEGER = POINTER(c_ulonglong)
341 # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
342 GetDiskFreeSpaceExW = WINFUNCTYPE(BOOL, LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER)(
343 ("GetDiskFreeSpaceExW", windll.kernel32))
345 # <http://msdn.microsoft.com/en-us/library/ms679360%28v=VS.85%29.aspx>
346 GetLastError = WINFUNCTYPE(DWORD)(("GetLastError", windll.kernel32))
348 have_GetDiskFreeSpaceExW = True
351 traceback.print_exc()
353 def get_disk_stats(whichdir, reserved_space=0):
354 """Return disk statistics for the storage disk, in the form of a dict
355 with the following fields.
356 total: total bytes on disk
357 free_for_root: bytes actually free on disk
358 free_for_nonroot: bytes free for "a non-privileged user" [Unix] or
359 the current user [Windows]; might take into
360 account quotas depending on platform
361 used: bytes used on disk
362 avail: bytes available excluding reserved space
363 An AttributeError can occur if the OS has no API to get disk information.
364 An EnvironmentError can occur if the OS call fails.
366 whichdir is a directory on the filesystem in question -- the
367 answer is about the filesystem, not about the directory, so the
368 directory is used only to specify which filesystem.
370 reserved_space is how many bytes to subtract from the answer, so
371 you can pass how many bytes you would like to leave unused on this
372 filesystem as reserved_space.
375 if have_GetDiskFreeSpaceExW:
376 # If this is a Windows system and GetDiskFreeSpaceExW is available, use it.
377 # (This might put up an error dialog unless
378 # SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX) has been called,
379 # which we do in allmydata.windows.fixups.initialize().)
381 n_free_for_nonroot = c_ulonglong(0)
382 n_total = c_ulonglong(0)
383 n_free_for_root = c_ulonglong(0)
384 retval = GetDiskFreeSpaceExW(whichdir, byref(n_free_for_nonroot),
386 byref(n_free_for_root))
388 raise OSError("Windows error %d attempting to get disk statistics for %r"
389 % (GetLastError(), whichdir))
390 free_for_nonroot = n_free_for_nonroot.value
391 total = n_total.value
392 free_for_root = n_free_for_root.value
394 # For Unix-like systems.
395 # <http://docs.python.org/library/os.html#os.statvfs>
396 # <http://opengroup.org/onlinepubs/7990989799/xsh/fstatvfs.html>
397 # <http://opengroup.org/onlinepubs/7990989799/xsh/sysstatvfs.h.html>
398 s = os.statvfs(whichdir)
401 # statvfs(2) is a wrapper around statfs(2).
402 # statvfs.f_frsize = statfs.f_bsize :
403 # "minimum unit of allocation" (statvfs)
404 # "fundamental file system block size" (statfs)
405 # statvfs.f_bsize = statfs.f_iosize = stat.st_blocks : preferred IO size
406 # on an encrypted home directory ("FileVault"), it gets f_blocks
407 # wrong, and s.f_blocks*s.f_frsize is twice the size of my disk,
408 # but s.f_bavail*s.f_frsize is correct
410 total = s.f_frsize * s.f_blocks
411 free_for_root = s.f_frsize * s.f_bfree
412 free_for_nonroot = s.f_frsize * s.f_bavail
414 # valid for all platforms:
415 used = total - free_for_root
416 avail = max(free_for_nonroot - reserved_space, 0)
418 return { 'total': total,
419 'free_for_root': free_for_root,
420 'free_for_nonroot': free_for_nonroot,
425 def get_available_space(whichdir, reserved_space):
426 """Returns available space for share storage in bytes, or None if no
427 API to get this information is available.
429 whichdir is a directory on the filesystem in question -- the
430 answer is about the filesystem, not about the directory, so the
431 directory is used only to specify which filesystem.
433 reserved_space is how many bytes to subtract from the answer, so
434 you can pass how many bytes you would like to leave unused on this
435 filesystem as reserved_space.
438 return get_disk_stats(whichdir, reserved_space)['avail']
439 except AttributeError:
441 except EnvironmentError:
442 log.msg("OS call to get disk statistics failed")