source file: /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/tempfile.py
file stats: 213 lines, 50 executed: 23.5% covered
   1. """Temporary files.
   2. 
   3. This module provides generic, low- and high-level interfaces for
   4. creating temporary files and directories.  The interfaces listed
   5. as "safe" just below can be used without fear of race conditions.
   6. Those listed as "unsafe" cannot, and are provided for backward
   7. compatibility only.
   8. 
   9. This module also provides some data items to the user:
  10. 
  11.   TMP_MAX  - maximum number of names that will be tried before
  12.              giving up.
  13.   template - the default prefix for all temporary names.
  14.              You may change this to control the default prefix.
  15.   tempdir  - If this is set to a string before the first use of
  16.              any routine from this module, it will be considered as
  17.              another candidate location to store temporary files.
  18. """
  19. 
  20. __all__ = [
  21.     "NamedTemporaryFile", "TemporaryFile", # high level safe interfaces
  22.     "mkstemp", "mkdtemp",                  # low level safe interfaces
  23.     "mktemp",                              # deprecated unsafe interface
  24.     "TMP_MAX", "gettempprefix",            # constants
  25.     "tempdir", "gettempdir"
  26.    ]
  27. 
  28. 
  29. # Imports.
  30. 
  31. import os as _os
  32. import errno as _errno
  33. from random import Random as _Random
  34. 
  35. if _os.name == 'mac':
  36.     import Carbon.Folder as _Folder
  37.     import Carbon.Folders as _Folders
  38. 
  39. try:
  40.     import fcntl as _fcntl
  41.     # If PYTHONCASEOK is set on Windows, stinking FCNTL.py gets
  42.     # imported, and we don't get an ImportError then.  Provoke
  43.     # an AttributeError instead in that case.
  44.     _fcntl.fcntl
  45. except (ImportError, AttributeError):
  46.     def _set_cloexec(fd):
  47.         pass
  48. else:
  49.     def _set_cloexec(fd):
  50.         try: flags = _fcntl.fcntl(fd, _fcntl.F_GETFD, 0)
  51.         except IOError: pass
  52.         else:
  53.             # flags read successfully, modify
  54.             flags |= _fcntl.FD_CLOEXEC
  55.             _fcntl.fcntl(fd, _fcntl.F_SETFD, flags)
  56. 
  57. 
  58. try:
  59.     import thread as _thread
  60. except ImportError:
  61.     import dummy_thread as _thread
  62. _allocate_lock = _thread.allocate_lock
  63. 
  64. _text_openflags = _os.O_RDWR | _os.O_CREAT | _os.O_EXCL
  65. if hasattr(_os, 'O_NOINHERIT'):
  66.     _text_openflags |= _os.O_NOINHERIT
  67. if hasattr(_os, 'O_NOFOLLOW'):
  68.     _text_openflags |= _os.O_NOFOLLOW
  69. 
  70. _bin_openflags = _text_openflags
  71. if hasattr(_os, 'O_BINARY'):
  72.     _bin_openflags |= _os.O_BINARY
  73. 
  74. if hasattr(_os, 'TMP_MAX'):
  75.     TMP_MAX = _os.TMP_MAX
  76. else:
  77.     TMP_MAX = 10000
  78. 
  79. template = "tmp"
  80. 
  81. tempdir = None
  82. 
  83. # Internal routines.
  84. 
  85. _once_lock = _allocate_lock()
  86. 
  87. class _RandomNameSequence:
  88.     """An instance of _RandomNameSequence generates an endless
  89.     sequence of unpredictable strings which can safely be incorporated
  90.     into file names.  Each string is six characters long.  Multiple
  91.     threads can safely use the same instance at the same time.
  92. 
  93.     _RandomNameSequence is an iterator."""
  94. 
  95.     characters = ("abcdefghijklmnopqrstuvwxyz" +
  96.                   "ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
  97.                   "0123456789-_")
  98. 
  99.     def __init__(self):
 100.         self.mutex = _allocate_lock()
 101.         self.rng = _Random()
 102.         self.normcase = _os.path.normcase
 103. 
 104.     def __iter__(self):
 105.         return self
 106. 
 107.     def next(self):
 108.         m = self.mutex
 109.         c = self.characters
 110.         choose = self.rng.choice
 111. 
 112.         m.acquire()
 113.         try:
 114.             letters = [choose(c) for dummy in "123456"]
 115.         finally:
 116.             m.release()
 117. 
 118.         return self.normcase(''.join(letters))
 119. 
 120. def _candidate_tempdir_list():
 121.     """Generate a list of candidate temporary directories which
 122.     _get_default_tempdir will try."""
 123. 
 124.     dirlist = []
 125. 
 126.     # First, try the environment.
 127.     for envname in 'TMPDIR', 'TEMP', 'TMP':
 128.         dirname = _os.getenv(envname)
 129.         if dirname: dirlist.append(dirname)
 130. 
 131.     # Failing that, try OS-specific locations.
 132.     if _os.name == 'mac':
 133.         try:
 134.             fsr = _Folder.FSFindFolder(_Folders.kOnSystemDisk,
 135.                                               _Folders.kTemporaryFolderType, 1)
 136.             dirname = fsr.as_pathname()
 137.             dirlist.append(dirname)
 138.         except _Folder.error:
 139.             pass
 140.     elif _os.name == 'riscos':
 141.         dirname = _os.getenv('Wimp$ScrapDir')
 142.         if dirname: dirlist.append(dirname)
 143.     elif _os.name == 'nt':
 144.         dirlist.extend([ r'c:\temp', r'c:\tmp', r'\temp', r'\tmp' ])
 145.     else:
 146.         dirlist.extend([ '/tmp', '/var/tmp', '/usr/tmp' ])
 147. 
 148.     # As a last resort, the current directory.
 149.     try:
 150.         dirlist.append(_os.getcwd())
 151.     except (AttributeError, _os.error):
 152.         dirlist.append(_os.curdir)
 153. 
 154.     return dirlist
 155. 
 156. def _get_default_tempdir():
 157.     """Calculate the default directory to use for temporary files.
 158.     This routine should be called exactly once.
 159. 
 160.     We determine whether or not a candidate temp dir is usable by
 161.     trying to create and write to a file in that directory.  If this
 162.     is successful, the test file is deleted.  To prevent denial of
 163.     service, the name of the test file must be randomized."""
 164. 
 165.     namer = _RandomNameSequence()
 166.     dirlist = _candidate_tempdir_list()
 167.     flags = _text_openflags
 168. 
 169.     for dir in dirlist:
 170.         if dir != _os.curdir:
 171.             dir = _os.path.normcase(_os.path.abspath(dir))
 172.         # Try only a few names per directory.
 173.         for seq in xrange(100):
 174.             name = namer.next()
 175.             filename = _os.path.join(dir, name)
 176.             try:
 177.                 fd = _os.open(filename, flags, 0600)
 178.                 fp = _os.fdopen(fd, 'w')
 179.                 fp.write('blat')
 180.                 fp.close()
 181.                 _os.unlink(filename)
 182.                 del fp, fd
 183.                 return dir
 184.             except (OSError, IOError), e:
 185.                 if e[0] != _errno.EEXIST:
 186.                     break # no point trying more names in this directory
 187.                 pass
 188.     raise IOError, (_errno.ENOENT,
 189.                     ("No usable temporary directory found in %s" % dirlist))
 190. 
 191. _name_sequence = None
 192. 
 193. def _get_candidate_names():
 194.     """Common setup sequence for all user-callable interfaces."""
 195. 
 196.     global _name_sequence
 197.     if _name_sequence is None:
 198.         _once_lock.acquire()
 199.         try:
 200.             if _name_sequence is None:
 201.                 _name_sequence = _RandomNameSequence()
 202.         finally:
 203.             _once_lock.release()
 204.     return _name_sequence
 205. 
 206. 
 207. def _mkstemp_inner(dir, pre, suf, flags):
 208.     """Code common to mkstemp, TemporaryFile, and NamedTemporaryFile."""
 209. 
 210.     names = _get_candidate_names()
 211. 
 212.     for seq in xrange(TMP_MAX):
 213.         name = names.next()
 214.         file = _os.path.join(dir, pre + name + suf)
 215.         try:
 216.             fd = _os.open(file, flags, 0600)
 217.             _set_cloexec(fd)
 218.             return (fd, file)
 219.         except OSError, e:
 220.             if e.errno == _errno.EEXIST:
 221.                 continue # try again
 222.             raise
 223. 
 224.     raise IOError, (_errno.EEXIST, "No usable temporary file name found")
 225. 
 226. 
 227. # User visible interfaces.
 228. 
 229. def gettempprefix():
 230.     """Accessor for tempdir.template."""
 231.     return template
 232. 
 233. tempdir = None
 234. 
 235. def gettempdir():
 236.     """Accessor for tempdir.tempdir."""
 237.     global tempdir
 238.     if tempdir is None:
 239.         _once_lock.acquire()
 240.         try:
 241.             if tempdir is None:
 242.                 tempdir = _get_default_tempdir()
 243.         finally:
 244.             _once_lock.release()
 245.     return tempdir
 246. 
 247. def mkstemp(suffix="", prefix=template, dir=None, text=False):
 248.     """mkstemp([suffix, [prefix, [dir, [text]]]])
 249.     User-callable function to create and return a unique temporary
 250.     file.  The return value is a pair (fd, name) where fd is the
 251.     file descriptor returned by os.open, and name is the filename.
 252. 
 253.     If 'suffix' is specified, the file name will end with that suffix,
 254.     otherwise there will be no suffix.
 255. 
 256.     If 'prefix' is specified, the file name will begin with that prefix,
 257.     otherwise a default prefix is used.
 258. 
 259.     If 'dir' is specified, the file will be created in that directory,
 260.     otherwise a default directory is used.
 261. 
 262.     If 'text' is specified and true, the file is opened in text
 263.     mode.  Else (the default) the file is opened in binary mode.  On
 264.     some operating systems, this makes no difference.
 265. 
 266.     The file is readable and writable only by the creating user ID.
 267.     If the operating system uses permission bits to indicate whether a
 268.     file is executable, the file is executable by no one. The file
 269.     descriptor is not inherited by children of this process.
 270. 
 271.     Caller is responsible for deleting the file when done with it.
 272.     """
 273. 
 274.     if dir is None:
 275.         dir = gettempdir()
 276. 
 277.     if text:
 278.         flags = _text_openflags
 279.     else:
 280.         flags = _bin_openflags
 281. 
 282.     return _mkstemp_inner(dir, prefix, suffix, flags)
 283. 
 284. 
 285. def mkdtemp(suffix="", prefix=template, dir=None):
 286.     """mkdtemp([suffix, [prefix, [dir]]])
 287.     User-callable function to create and return a unique temporary
 288.     directory.  The return value is the pathname of the directory.
 289. 
 290.     Arguments are as for mkstemp, except that the 'text' argument is
 291.     not accepted.
 292. 
 293.     The directory is readable, writable, and searchable only by the
 294.     creating user.
 295. 
 296.     Caller is responsible for deleting the directory when done with it.
 297.     """
 298. 
 299.     if dir is None:
 300.         dir = gettempdir()
 301. 
 302.     names = _get_candidate_names()
 303. 
 304.     for seq in xrange(TMP_MAX):
 305.         name = names.next()
 306.         file = _os.path.join(dir, prefix + name + suffix)
 307.         try:
 308.             _os.mkdir(file, 0700)
 309.             return file
 310.         except OSError, e:
 311.             if e.errno == _errno.EEXIST:
 312.                 continue # try again
 313.             raise
 314. 
 315.     raise IOError, (_errno.EEXIST, "No usable temporary directory name found")
 316. 
 317. def mktemp(suffix="", prefix=template, dir=None):
 318.     """mktemp([suffix, [prefix, [dir]]])
 319.     User-callable function to return a unique temporary file name.  The
 320.     file is not created.
 321. 
 322.     Arguments are as for mkstemp, except that the 'text' argument is
 323.     not accepted.
 324. 
 325.     This function is unsafe and should not be used.  The file name
 326.     refers to a file that did not exist at some point, but by the time
 327.     you get around to creating it, someone else may have beaten you to
 328.     the punch.
 329.     """
 330. 
 331. ##    from warnings import warn as _warn
 332. ##    _warn("mktemp is a potential security risk to your program",
 333. ##          RuntimeWarning, stacklevel=2)
 334. 
 335.     if dir is None:
 336.         dir = gettempdir()
 337. 
 338.     names = _get_candidate_names()
 339.     for seq in xrange(TMP_MAX):
 340.         name = names.next()
 341.         file = _os.path.join(dir, prefix + name + suffix)
 342.         if not _os.path.exists(file):
 343.             return file
 344. 
 345.     raise IOError, (_errno.EEXIST, "No usable temporary filename found")
 346. 
 347. class _TemporaryFileWrapper:
 348.     """Temporary file wrapper
 349. 
 350.     This class provides a wrapper around files opened for
 351.     temporary use.  In particular, it seeks to automatically
 352.     remove the file when it is no longer needed.
 353.     """
 354. 
 355.     def __init__(self, file, name):
 356.         self.file = file
 357.         self.name = name
 358.         self.close_called = False
 359. 
 360.     def __getattr__(self, name):
 361.         file = self.__dict__['file']
 362.         a = getattr(file, name)
 363.         if type(a) != type(0):
 364.             setattr(self, name, a)
 365.         return a
 366. 
 367.     # NT provides delete-on-close as a primitive, so we don't need
 368.     # the wrapper to do anything special.  We still use it so that
 369.     # file.name is useful (i.e. not "(fdopen)") with NamedTemporaryFile.
 370.     if _os.name != 'nt':
 371. 
 372.         # Cache the unlinker so we don't get spurious errors at
 373.         # shutdown when the module-level "os" is None'd out.  Note
 374.         # that this must be referenced as self.unlink, because the
 375.         # name TemporaryFileWrapper may also get None'd out before
 376.         # __del__ is called.
 377.         unlink = _os.unlink
 378. 
 379.         def close(self):
 380.             if not self.close_called:
 381.                 self.close_called = True
 382.                 self.file.close()
 383.                 self.unlink(self.name)
 384. 
 385.         def __del__(self):
 386.             self.close()
 387. 
 388. def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="",
 389.                        prefix=template, dir=None):
 390.     """Create and return a temporary file.
 391.     Arguments:
 392.     'prefix', 'suffix', 'dir' -- as for mkstemp.
 393.     'mode' -- the mode argument to os.fdopen (default "w+b").
 394.     'bufsize' -- the buffer size argument to os.fdopen (default -1).
 395.     The file is created as mkstemp() would do it.
 396. 
 397.     Returns a file object; the name of the file is accessible as
 398.     file.name.  The file will be automatically deleted when it is
 399.     closed.
 400.     """
 401. 
 402.     if dir is None:
 403.         dir = gettempdir()
 404. 
 405.     if 'b' in mode:
 406.         flags = _bin_openflags
 407.     else:
 408.         flags = _text_openflags
 409. 
 410.     # Setting O_TEMPORARY in the flags causes the OS to delete
 411.     # the file when it is closed.  This is only supported by Windows.
 412.     if _os.name == 'nt':
 413.         flags |= _os.O_TEMPORARY
 414. 
 415.     (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags)
 416.     file = _os.fdopen(fd, mode, bufsize)
 417.     return _TemporaryFileWrapper(file, name)
 418. 
 419. if _os.name != 'posix' or _os.sys.platform == 'cygwin':
 420.     # On non-POSIX and Cygwin systems, assume that we cannot unlink a file
 421.     # while it is open.
 422.     TemporaryFile = NamedTemporaryFile
 423. 
 424. else:
 425.     def TemporaryFile(mode='w+b', bufsize=-1, suffix="",
 426.                       prefix=template, dir=None):
 427.         """Create and return a temporary file.
 428.         Arguments:
 429.         'prefix', 'suffix', 'directory' -- as for mkstemp.
 430.         'mode' -- the mode argument to os.fdopen (default "w+b").
 431.         'bufsize' -- the buffer size argument to os.fdopen (default -1).
 432.         The file is created as mkstemp() would do it.
 433. 
 434.         Returns a file object.  The file has no name, and will cease to
 435.         exist when it is closed.
 436.         """
 437. 
 438.         if dir is None:
 439.             dir = gettempdir()
 440. 
 441.         if 'b' in mode:
 442.             flags = _bin_openflags
 443.         else:
 444.             flags = _text_openflags
 445. 
 446.         (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags)
 447.         try:
 448.             _os.unlink(name)
 449.             return _os.fdopen(fd, mode, bufsize)
 450.         except:
 451.             _os.close(fd)
 452.             raise