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):
227 def open_or_create(fname, binarymode=True):
229 return open(fname, binarymode and "r+b" or "r+")
230 except EnvironmentError:
231 return open(fname, binarymode and "w+b" or "w+")
236 for root, dirs, files in os.walk(basedir):
238 fn = os.path.join(root, f)
239 size += os.path.getsize(fn)
243 def move_into_place(source, dest):
244 """Atomically replace a file, or as near to it as the platform allows.
245 The dest file may or may not exist."""
246 if "win32" in sys.platform.lower():
247 remove_if_possible(dest)
248 os.rename(source, dest)
250 def write_atomically(target, contents, mode="b"):
251 f = open(target+".tmp", "w"+mode)
256 move_into_place(target+".tmp", target)
258 def write(path, data):
259 wf = open(path, "wb")
266 rf = open(path, "rb")
272 def put_file(pathname, inf):
273 # TODO: create temporary file and move into place?
274 outf = open(os.path.expanduser(pathname), "wb")
277 data = inf.read(32768)
285 # Work around <http://bugs.python.org/issue3426>. This code is adapted from
286 # <http://svn.python.org/view/python/trunk/Lib/ntpath.py?revision=78247&view=markup>
287 # with some simplifications.
289 _getfullpathname = None
291 from nt import _getfullpathname
295 def abspath_expanduser_unicode(path):
296 """Return the absolute version of a path."""
297 assert isinstance(path, unicode), path
299 path = os.path.expanduser(path)
302 # On Windows, os.path.isabs will return True for paths without a drive letter,
303 # e.g. "\\". See <http://bugs.python.org/issue1669539>.
305 path = _getfullpathname(path or u".")
309 if not os.path.isabs(path):
310 path = os.path.join(os.getcwdu(), path)
312 # We won't hit <http://bugs.python.org/issue5827> because
313 # there is always at least one Unicode path component.
314 return os.path.normpath(path)
317 have_GetDiskFreeSpaceExW = False
318 if sys.platform == "win32":
320 from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_ulonglong
321 from ctypes.wintypes import BOOL, DWORD, LPCWSTR
323 # <http://msdn.microsoft.com/en-us/library/aa383742%28v=VS.85%29.aspx>
324 PULARGE_INTEGER = POINTER(c_ulonglong)
326 # <http://msdn.microsoft.com/en-us/library/aa364937%28VS.85%29.aspx>
327 GetDiskFreeSpaceExW = WINFUNCTYPE(BOOL, LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER)(
328 ("GetDiskFreeSpaceExW", windll.kernel32))
330 # <http://msdn.microsoft.com/en-us/library/ms679360%28v=VS.85%29.aspx>
331 GetLastError = WINFUNCTYPE(DWORD)(("GetLastError", windll.kernel32))
333 have_GetDiskFreeSpaceExW = True
336 traceback.print_exc()
338 def get_disk_stats(whichdir, reserved_space=0):
339 """Return disk statistics for the storage disk, in the form of a dict
340 with the following fields.
341 total: total bytes on disk
342 free_for_root: bytes actually free on disk
343 free_for_nonroot: bytes free for "a non-privileged user" [Unix] or
344 the current user [Windows]; might take into
345 account quotas depending on platform
346 used: bytes used on disk
347 avail: bytes available excluding reserved space
348 An AttributeError can occur if the OS has no API to get disk information.
349 An EnvironmentError can occur if the OS call fails.
351 whichdir is a directory on the filesystem in question -- the
352 answer is about the filesystem, not about the directory, so the
353 directory is used only to specify which filesystem.
355 reserved_space is how many bytes to subtract from the answer, so
356 you can pass how many bytes you would like to leave unused on this
357 filesystem as reserved_space.
360 if have_GetDiskFreeSpaceExW:
361 # If this is a Windows system and GetDiskFreeSpaceExW is available, use it.
362 # (This might put up an error dialog unless
363 # SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX) has been called,
364 # which we do in allmydata.windows.fixups.initialize().)
366 n_free_for_nonroot = c_ulonglong(0)
367 n_total = c_ulonglong(0)
368 n_free_for_root = c_ulonglong(0)
369 retval = GetDiskFreeSpaceExW(whichdir, byref(n_free_for_nonroot),
371 byref(n_free_for_root))
373 raise OSError("Windows error %d attempting to get disk statistics for %r"
374 % (GetLastError(), whichdir))
375 free_for_nonroot = n_free_for_nonroot.value
376 total = n_total.value
377 free_for_root = n_free_for_root.value
379 # For Unix-like systems.
380 # <http://docs.python.org/library/os.html#os.statvfs>
381 # <http://opengroup.org/onlinepubs/7990989799/xsh/fstatvfs.html>
382 # <http://opengroup.org/onlinepubs/7990989799/xsh/sysstatvfs.h.html>
383 s = os.statvfs(whichdir)
386 # statvfs(2) is a wrapper around statfs(2).
387 # statvfs.f_frsize = statfs.f_bsize :
388 # "minimum unit of allocation" (statvfs)
389 # "fundamental file system block size" (statfs)
390 # statvfs.f_bsize = statfs.f_iosize = stat.st_blocks : preferred IO size
391 # on an encrypted home directory ("FileVault"), it gets f_blocks
392 # wrong, and s.f_blocks*s.f_frsize is twice the size of my disk,
393 # but s.f_bavail*s.f_frsize is correct
395 total = s.f_frsize * s.f_blocks
396 free_for_root = s.f_frsize * s.f_bfree
397 free_for_nonroot = s.f_frsize * s.f_bavail
399 # valid for all platforms:
400 used = total - free_for_root
401 avail = max(free_for_nonroot - reserved_space, 0)
403 return { 'total': total,
404 'free_for_root': free_for_root,
405 'free_for_nonroot': free_for_nonroot,
410 def get_available_space(whichdir, reserved_space):
411 """Returns available space for share storage in bytes, or None if no
412 API to get this information is available.
414 whichdir is a directory on the filesystem in question -- the
415 answer is about the filesystem, not about the directory, so the
416 directory is used only to specify which filesystem.
418 reserved_space is how many bytes to subtract from the answer, so
419 you can pass how many bytes you would like to leave unused on this
420 filesystem as reserved_space.
423 return get_disk_stats(whichdir, reserved_space)['avail']
424 except AttributeError:
426 except EnvironmentError:
427 log.msg("OS call to get disk statistics failed")