source file: /disk/u/t/dev/python-svn/Lib/tempfile.py
file stats: 319 lines, 241 executed: 75.5% 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. "SpooledTemporaryFile",
23. "mkstemp", "mkdtemp", # low level safe interfaces
24. "mktemp", # deprecated unsafe interface
25. "TMP_MAX", "gettempprefix", # constants
26. "tempdir", "gettempdir"
27. ]
28.
29.
30. # Imports.
31.
32. import os as _os
33. import errno as _errno
34. from random import Random as _Random
35.
36. if _os.name == 'mac':
37. import Carbon.Folder as _Folder
38. import Carbon.Folders as _Folders
39.
40. try:
41. from cStringIO import StringIO as _StringIO
42. except:
43. from StringIO import StringIO as _StringIO
44.
45. try:
46. import fcntl as _fcntl
47. except ImportError:
48. def _set_cloexec(fd):
49. pass
50. else:
51. def _set_cloexec(fd):
52. try:
53. flags = _fcntl.fcntl(fd, _fcntl.F_GETFD, 0)
54. except IOError:
55. pass
56. else:
57. # flags read successfully, modify
58. flags |= _fcntl.FD_CLOEXEC
59. _fcntl.fcntl(fd, _fcntl.F_SETFD, flags)
60.
61.
62. try:
63. import thread as _thread
64. except ImportError:
65. import dummy_thread as _thread
66. _allocate_lock = _thread.allocate_lock
67.
68. _text_openflags = _os.O_RDWR | _os.O_CREAT | _os.O_EXCL
69. if hasattr(_os, 'O_NOINHERIT'):
70. _text_openflags |= _os.O_NOINHERIT
71. if hasattr(_os, 'O_NOFOLLOW'):
72. _text_openflags |= _os.O_NOFOLLOW
73.
74. _bin_openflags = _text_openflags
75. if hasattr(_os, 'O_BINARY'):
76. _bin_openflags |= _os.O_BINARY
77.
78. if hasattr(_os, 'TMP_MAX'):
79. TMP_MAX = _os.TMP_MAX
80. else:
81. TMP_MAX = 10000
82.
83. template = "tmp"
84.
85. tempdir = None
86.
87. # Internal routines.
88.
89. _once_lock = _allocate_lock()
90.
91. if hasattr(_os, "lstat"):
92. _stat = _os.lstat
93. elif hasattr(_os, "stat"):
94. _stat = _os.stat
95. else:
96. # Fallback. All we need is something that raises os.error if the
97. # file doesn't exist.
98. def _stat(fn):
99. try:
100. f = open(fn)
101. except IOError:
102. raise _os.error
103. f.close()
104.
105. def _exists(fn):
106. try:
107. _stat(fn)
108. except _os.error:
109. return False
110. else:
111. return True
112.
113. class _RandomNameSequence:
114. """An instance of _RandomNameSequence generates an endless
115. sequence of unpredictable strings which can safely be incorporated
116. into file names. Each string is six characters long. Multiple
117. threads can safely use the same instance at the same time.
118.
119. _RandomNameSequence is an iterator."""
120.
121. characters = ("abcdefghijklmnopqrstuvwxyz" +
122. "ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
123. "0123456789_")
124.
125. def __init__(self):
126. self.mutex = _allocate_lock()
127. self.rng = _Random()
128. self.normcase = _os.path.normcase
129.
130. def __iter__(self):
131. return self
132.
133. def next(self):
134. m = self.mutex
135. c = self.characters
136. choose = self.rng.choice
137.
138. m.acquire()
139. try:
140. letters = [choose(c) for dummy in "123456"]
141. finally:
142. m.release()
143.
144. return self.normcase(''.join(letters))
145.
146. def _candidate_tempdir_list():
147. """Generate a list of candidate temporary directories which
148. _get_default_tempdir will try."""
149.
150. dirlist = []
151.
152. # First, try the environment.
153. for envname in 'TMPDIR', 'TEMP', 'TMP':
154. dirname = _os.getenv(envname)
155. if dirname: dirlist.append(dirname)
156.
157. # Failing that, try OS-specific locations.
158. if _os.name == 'mac':
159. try:
160. fsr = _Folder.FSFindFolder(_Folders.kOnSystemDisk,
161. _Folders.kTemporaryFolderType, 1)
162. dirname = fsr.as_pathname()
163. dirlist.append(dirname)
164. except _Folder.error:
165. pass
166. elif _os.name == 'riscos':
167. dirname = _os.getenv('Wimp$ScrapDir')
168. if dirname: dirlist.append(dirname)
169. elif _os.name == 'nt':
170. dirlist.extend([ r'c:\temp', r'c:\tmp', r'\temp', r'\tmp' ])
171. else:
172. dirlist.extend([ '/tmp', '/var/tmp', '/usr/tmp' ])
173.
174. # As a last resort, the current directory.
175. try:
176. dirlist.append(_os.getcwd())
177. except (AttributeError, _os.error):
178. dirlist.append(_os.curdir)
179.
180. return dirlist
181.
182. def _get_default_tempdir():
183. """Calculate the default directory to use for temporary files.
184. This routine should be called exactly once.
185.
186. We determine whether or not a candidate temp dir is usable by
187. trying to create and write to a file in that directory. If this
188. is successful, the test file is deleted. To prevent denial of
189. service, the name of the test file must be randomized."""
190.
191. namer = _RandomNameSequence()
192. dirlist = _candidate_tempdir_list()
193. flags = _text_openflags
194.
195. for dir in dirlist:
196. if dir != _os.curdir:
197. dir = _os.path.normcase(_os.path.abspath(dir))
198. # Try only a few names per directory.
199. for seq in xrange(100):
200. name = namer.next()
201. filename = _os.path.join(dir, name)
202. try:
203. fd = _os.open(filename, flags, 0600)
204. fp = _os.fdopen(fd, 'w')
205. fp.write('blat')
206. fp.close()
207. _os.unlink(filename)
208. del fp, fd
209. return dir
210. except (OSError, IOError), e:
211. if e[0] != _errno.EEXIST:
212. break # no point trying more names in this directory
213. pass
214. raise IOError, (_errno.ENOENT,
215. ("No usable temporary directory found in %s" % dirlist))
216.
217. _name_sequence = None
218.
219. def _get_candidate_names():
220. """Common setup sequence for all user-callable interfaces."""
221.
222. global _name_sequence
223. if _name_sequence is None:
224. _once_lock.acquire()
225. try:
226. if _name_sequence is None:
227. _name_sequence = _RandomNameSequence()
228. finally:
229. _once_lock.release()
230. return _name_sequence
231.
232.
233. def _mkstemp_inner(dir, pre, suf, flags):
234. """Code common to mkstemp, TemporaryFile, and NamedTemporaryFile."""
235.
236. names = _get_candidate_names()
237.
238. for seq in xrange(TMP_MAX):
239. name = names.next()
240. file = _os.path.join(dir, pre + name + suf)
241. try:
242. fd = _os.open(file, flags, 0600)
243. _set_cloexec(fd)
244. return (fd, _os.path.abspath(file))
245. except OSError, e:
246. if e.errno == _errno.EEXIST:
247. continue # try again
248. raise
249.
250. raise IOError, (_errno.EEXIST, "No usable temporary file name found")
251.
252.
253. # User visible interfaces.
254.
255. def gettempprefix():
256. """Accessor for tempdir.template."""
257. return template
258.
259. tempdir = None
260.
261. def gettempdir():
262. """Accessor for tempdir.tempdir."""
263. global tempdir
264. if tempdir is None:
265. _once_lock.acquire()
266. try:
267. if tempdir is None:
268. tempdir = _get_default_tempdir()
269. finally:
270. _once_lock.release()
271. return tempdir
272.
273. def mkstemp(suffix="", prefix=template, dir=None, text=False):
274. """mkstemp([suffix, [prefix, [dir, [text]]]])
275. User-callable function to create and return a unique temporary
276. file. The return value is a pair (fd, name) where fd is the
277. file descriptor returned by os.open, and name is the filename.
278.
279. If 'suffix' is specified, the file name will end with that suffix,
280. otherwise there will be no suffix.
281.
282. If 'prefix' is specified, the file name will begin with that prefix,
283. otherwise a default prefix is used.
284.
285. If 'dir' is specified, the file will be created in that directory,
286. otherwise a default directory is used.
287.
288. If 'text' is specified and true, the file is opened in text
289. mode. Else (the default) the file is opened in binary mode. On
290. some operating systems, this makes no difference.
291.
292. The file is readable and writable only by the creating user ID.
293. If the operating system uses permission bits to indicate whether a
294. file is executable, the file is executable by no one. The file
295. descriptor is not inherited by children of this process.
296.
297. Caller is responsible for deleting the file when done with it.
298. """
299.
300. if dir is None:
301. dir = gettempdir()
302.
303. if text:
304. flags = _text_openflags
305. else:
306. flags = _bin_openflags
307.
308. return _mkstemp_inner(dir, prefix, suffix, flags)
309.
310.
311. def mkdtemp(suffix="", prefix=template, dir=None):
312. """mkdtemp([suffix, [prefix, [dir]]])
313. User-callable function to create and return a unique temporary
314. directory. The return value is the pathname of the directory.
315.
316. Arguments are as for mkstemp, except that the 'text' argument is
317. not accepted.
318.
319. The directory is readable, writable, and searchable only by the
320. creating user.
321.
322. Caller is responsible for deleting the directory when done with it.
323. """
324.
325. if dir is None:
326. dir = gettempdir()
327.
328. names = _get_candidate_names()
329.
330. for seq in xrange(TMP_MAX):
331. name = names.next()
332. file = _os.path.join(dir, prefix + name + suffix)
333. try:
334. _os.mkdir(file, 0700)
335. return file
336. except OSError, e:
337. if e.errno == _errno.EEXIST:
338. continue # try again
339. raise
340.
341. raise IOError, (_errno.EEXIST, "No usable temporary directory name found")
342.
343. def mktemp(suffix="", prefix=template, dir=None):
344. """mktemp([suffix, [prefix, [dir]]])
345. User-callable function to return a unique temporary file name. The
346. file is not created.
347.
348. Arguments are as for mkstemp, except that the 'text' argument is
349. not accepted.
350.
351. This function is unsafe and should not be used. The file name
352. refers to a file that did not exist at some point, but by the time
353. you get around to creating it, someone else may have beaten you to
354. the punch.
355. """
356.
357. ## from warnings import warn as _warn
358. ## _warn("mktemp is a potential security risk to your program",
359. ## RuntimeWarning, stacklevel=2)
360.
361. if dir is None:
362. dir = gettempdir()
363.
364. names = _get_candidate_names()
365. for seq in xrange(TMP_MAX):
366. name = names.next()
367. file = _os.path.join(dir, prefix + name + suffix)
368. if not _exists(file):
369. return file
370.
371. raise IOError, (_errno.EEXIST, "No usable temporary filename found")
372.
373. class _TemporaryFileWrapper:
374. """Temporary file wrapper
375.
376. This class provides a wrapper around files opened for
377. temporary use. In particular, it seeks to automatically
378. remove the file when it is no longer needed.
379. """
380.
381. def __init__(self, file, name, delete=True):
382. self.file = file
383. self.name = name
384. self.close_called = False
385. self.delete = delete
386.
387. def __getattr__(self, name):
388. file = self.__dict__['file']
389. a = getattr(file, name)
390. if type(a) != type(0):
391. setattr(self, name, a)
392. return a
393.
394. # NT provides delete-on-close as a primitive, so we don't need
395. # the wrapper to do anything special. We still use it so that
396. # file.name is useful (i.e. not "(fdopen)") with NamedTemporaryFile.
397. if _os.name != 'nt':
398.
399. # Cache the unlinker so we don't get spurious errors at
400. # shutdown when the module-level "os" is None'd out. Note
401. # that this must be referenced as self.unlink, because the
402. # name TemporaryFileWrapper may also get None'd out before
403. # __del__ is called.
404. unlink = _os.unlink
405.
406. def close(self):
407. if not self.close_called:
408. self.close_called = True
409. self.file.close()
410. if self.delete:
411. self.unlink(self.name)
412.
413. def __del__(self):
414. self.close()
415.
416. def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="",
417. prefix=template, dir=None, delete=True):
418. """Create and return a temporary file.
419. Arguments:
420. 'prefix', 'suffix', 'dir' -- as for mkstemp.
421. 'mode' -- the mode argument to os.fdopen (default "w+b").
422. 'bufsize' -- the buffer size argument to os.fdopen (default -1).
423. 'delete' -- whether the file is deleted on close (default True).
424. The file is created as mkstemp() would do it.
425.
426. Returns an object with a file-like interface; the name of the file
427. is accessible as file.name. The file will be automatically deleted
428. when it is closed unless the 'delete' argument is set to False.
429. """
430.
431. if dir is None:
432. dir = gettempdir()
433.
434. if 'b' in mode:
435. flags = _bin_openflags
436. else:
437. flags = _text_openflags
438.
439. # Setting O_TEMPORARY in the flags causes the OS to delete
440. # the file when it is closed. This is only supported by Windows.
441. if _os.name == 'nt' and delete:
442. flags |= _os.O_TEMPORARY
443.
444. (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags)
445. file = _os.fdopen(fd, mode, bufsize)
446. return _TemporaryFileWrapper(file, name, delete)
447.
448. if _os.name != 'posix' or _os.sys.platform == 'cygwin':
449. # On non-POSIX and Cygwin systems, assume that we cannot unlink a file
450. # while it is open.
451. TemporaryFile = NamedTemporaryFile
452.
453. else:
454. def TemporaryFile(mode='w+b', bufsize=-1, suffix="",
455. prefix=template, dir=None):
456. """Create and return a temporary file.
457. Arguments:
458. 'prefix', 'suffix', 'dir' -- as for mkstemp.
459. 'mode' -- the mode argument to os.fdopen (default "w+b").
460. 'bufsize' -- the buffer size argument to os.fdopen (default -1).
461. The file is created as mkstemp() would do it.
462.
463. Returns an object with a file-like interface. The file has no
464. name, and will cease to exist when it is closed.
465. """
466.
467. if dir is None:
468. dir = gettempdir()
469.
470. if 'b' in mode:
471. flags = _bin_openflags
472. else:
473. flags = _text_openflags
474.
475. (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags)
476. try:
477. _os.unlink(name)
478. return _os.fdopen(fd, mode, bufsize)
479. except:
480. _os.close(fd)
481. raise
482.
483. class SpooledTemporaryFile:
484. """Temporary file wrapper, specialized to switch from
485. StringIO to a real file when it exceeds a certain size or
486. when a fileno is needed.
487. """
488. _rolled = False
489.
490. def __init__(self, max_size=0, mode='w+b', bufsize=-1,
491. suffix="", prefix=template, dir=None):
492. self._file = _StringIO()
493. self._max_size = max_size
494. self._rolled = False
495. self._TemporaryFileArgs = (mode, bufsize, suffix, prefix, dir)
496.
497. def _check(self, file):
498. if self._rolled: return
499. max_size = self._max_size
500. if max_size and file.tell() > max_size:
501. self.rollover()
502.
503. def rollover(self):
504. if self._rolled: return
505. file = self._file
506. newfile = self._file = TemporaryFile(*self._TemporaryFileArgs)
507. del self._TemporaryFileArgs
508.
509. newfile.write(file.getvalue())
510. newfile.seek(file.tell(), 0)
511.
512. self._rolled = True
513.
514. # file protocol
515. def __iter__(self):
516. return self._file.__iter__()
517.
518. def close(self):
519. self._file.close()
520.
521. @property
522. def closed(self):
523. return self._file.closed
524.
525. @property
526. def encoding(self):
527. return self._file.encoding
528.
529. def fileno(self):
530. self.rollover()
531. return self._file.fileno()
532.
533. def flush(self):
534. self._file.flush()
535.
536. def isatty(self):
537. return self._file.isatty()
538.
539. @property
540. def mode(self):
541. return self._file.mode
542.
543. @property
544. def name(self):
545. return self._file.name
546.
547. @property
548. def newlines(self):
549. return self._file.newlines
550.
551. def next(self):
552. return self._file.next
553.
554. def read(self, *args):
555. return self._file.read(*args)
556.
557. def readline(self, *args):
558. return self._file.readline(*args)
559.
560. def readlines(self, *args):
561. return self._file.readlines(*args)
562.
563. def seek(self, *args):
564. self._file.seek(*args)
565.
566. @property
567. def softspace(self):
568. return self._file.softspace
569.
570. def tell(self):
571. return self._file.tell()
572.
573. def truncate(self):
574. self._file.truncate()
575.
576. def write(self, s):
577. file = self._file
578. rv = file.write(s)
579. self._check(file)
580. return rv
581.
582. def writelines(self, iterable):
583. file = self._file
584. rv = file.writelines(iterable)
585. self._check(file)
586. return rv
587.
588. def xreadlines(self, *args):
589. return self._file.xreadlines(*args)