When open_urlresource() fails, HTTPException is another possible error
[python.git] / Lib / os.py
blobe8a011337c3980b0e8dd7f2ae0fc8436dd6ba595
1 r"""OS routines for Mac, NT, or Posix depending on what system we're on.
3 This exports:
4 - all functions from posix, nt, os2, or ce, e.g. unlink, stat, etc.
5 - os.path is one of the modules posixpath, or ntpath
6 - os.name is 'posix', 'nt', 'os2', 'ce' or 'riscos'
7 - os.curdir is a string representing the current directory ('.' or ':')
8 - os.pardir is a string representing the parent directory ('..' or '::')
9 - os.sep is the (or a most common) pathname separator ('/' or ':' or '\\')
10 - os.extsep is the extension separator ('.' or '/')
11 - os.altsep is the alternate pathname separator (None or '/')
12 - os.pathsep is the component separator used in $PATH etc
13 - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
14 - os.defpath is the default search path for executables
15 - os.devnull is the file path of the null device ('/dev/null', etc.)
17 Programs that import and use 'os' stand a better chance of being
18 portable between different platforms. Of course, they must then
19 only use functions that are defined by all platforms (e.g., unlink
20 and opendir), and leave all pathname manipulation to os.path
21 (e.g., split and join).
22 """
26 import sys, errno
28 _names = sys.builtin_module_names
30 # Note: more names are added to __all__ later.
31 __all__ = ["altsep", "curdir", "pardir", "sep", "extsep", "pathsep", "linesep",
32 "defpath", "name", "path", "devnull",
33 "SEEK_SET", "SEEK_CUR", "SEEK_END"]
35 def _get_exports_list(module):
36 try:
37 return list(module.__all__)
38 except AttributeError:
39 return [n for n in dir(module) if n[0] != '_']
41 if 'posix' in _names:
42 name = 'posix'
43 linesep = '\n'
44 from posix import *
45 try:
46 from posix import _exit
47 except ImportError:
48 pass
49 import posixpath as path
51 import posix
52 __all__.extend(_get_exports_list(posix))
53 del posix
55 elif 'nt' in _names:
56 name = 'nt'
57 linesep = '\r\n'
58 from nt import *
59 try:
60 from nt import _exit
61 except ImportError:
62 pass
63 import ntpath as path
65 import nt
66 __all__.extend(_get_exports_list(nt))
67 del nt
69 elif 'os2' in _names:
70 name = 'os2'
71 linesep = '\r\n'
72 from os2 import *
73 try:
74 from os2 import _exit
75 except ImportError:
76 pass
77 if sys.version.find('EMX GCC') == -1:
78 import ntpath as path
79 else:
80 import os2emxpath as path
81 from _emx_link import link
83 import os2
84 __all__.extend(_get_exports_list(os2))
85 del os2
87 elif 'ce' in _names:
88 name = 'ce'
89 linesep = '\r\n'
90 from ce import *
91 try:
92 from ce import _exit
93 except ImportError:
94 pass
95 # We can use the standard Windows path.
96 import ntpath as path
98 import ce
99 __all__.extend(_get_exports_list(ce))
100 del ce
102 elif 'riscos' in _names:
103 name = 'riscos'
104 linesep = '\n'
105 from riscos import *
106 try:
107 from riscos import _exit
108 except ImportError:
109 pass
110 import riscospath as path
112 import riscos
113 __all__.extend(_get_exports_list(riscos))
114 del riscos
116 else:
117 raise ImportError, 'no os specific module found'
119 sys.modules['os.path'] = path
120 from os.path import (curdir, pardir, sep, pathsep, defpath, extsep, altsep,
121 devnull)
123 del _names
125 # Python uses fixed values for the SEEK_ constants; they are mapped
126 # to native constants if necessary in posixmodule.c
127 SEEK_SET = 0
128 SEEK_CUR = 1
129 SEEK_END = 2
133 # Super directory utilities.
134 # (Inspired by Eric Raymond; the doc strings are mostly his)
136 def makedirs(name, mode=0777):
137 """makedirs(path [, mode=0777])
139 Super-mkdir; create a leaf directory and all intermediate ones.
140 Works like mkdir, except that any intermediate path segment (not
141 just the rightmost) will be created if it does not exist. This is
142 recursive.
145 head, tail = path.split(name)
146 if not tail:
147 head, tail = path.split(head)
148 if head and tail and not path.exists(head):
149 try:
150 makedirs(head, mode)
151 except OSError, e:
152 # be happy if someone already created the path
153 if e.errno != errno.EEXIST:
154 raise
155 if tail == curdir: # xxx/newdir/. exists if xxx/newdir exists
156 return
157 mkdir(name, mode)
159 def removedirs(name):
160 """removedirs(path)
162 Super-rmdir; remove a leaf directory and all empty intermediate
163 ones. Works like rmdir except that, if the leaf directory is
164 successfully removed, directories corresponding to rightmost path
165 segments will be pruned away until either the whole path is
166 consumed or an error occurs. Errors during this latter phase are
167 ignored -- they generally mean that a directory was not empty.
170 rmdir(name)
171 head, tail = path.split(name)
172 if not tail:
173 head, tail = path.split(head)
174 while head and tail:
175 try:
176 rmdir(head)
177 except error:
178 break
179 head, tail = path.split(head)
181 def renames(old, new):
182 """renames(old, new)
184 Super-rename; create directories as necessary and delete any left
185 empty. Works like rename, except creation of any intermediate
186 directories needed to make the new pathname good is attempted
187 first. After the rename, directories corresponding to rightmost
188 path segments of the old name will be pruned way until either the
189 whole path is consumed or a nonempty directory is found.
191 Note: this function can fail with the new directory structure made
192 if you lack permissions needed to unlink the leaf directory or
193 file.
196 head, tail = path.split(new)
197 if head and tail and not path.exists(head):
198 makedirs(head)
199 rename(old, new)
200 head, tail = path.split(old)
201 if head and tail:
202 try:
203 removedirs(head)
204 except error:
205 pass
207 __all__.extend(["makedirs", "removedirs", "renames"])
209 def walk(top, topdown=True, onerror=None, followlinks=False):
210 """Directory tree generator.
212 For each directory in the directory tree rooted at top (including top
213 itself, but excluding '.' and '..'), yields a 3-tuple
215 dirpath, dirnames, filenames
217 dirpath is a string, the path to the directory. dirnames is a list of
218 the names of the subdirectories in dirpath (excluding '.' and '..').
219 filenames is a list of the names of the non-directory files in dirpath.
220 Note that the names in the lists are just names, with no path components.
221 To get a full path (which begins with top) to a file or directory in
222 dirpath, do os.path.join(dirpath, name).
224 If optional arg 'topdown' is true or not specified, the triple for a
225 directory is generated before the triples for any of its subdirectories
226 (directories are generated top down). If topdown is false, the triple
227 for a directory is generated after the triples for all of its
228 subdirectories (directories are generated bottom up).
230 When topdown is true, the caller can modify the dirnames list in-place
231 (e.g., via del or slice assignment), and walk will only recurse into the
232 subdirectories whose names remain in dirnames; this can be used to prune
233 the search, or to impose a specific order of visiting. Modifying
234 dirnames when topdown is false is ineffective, since the directories in
235 dirnames have already been generated by the time dirnames itself is
236 generated.
238 By default errors from the os.listdir() call are ignored. If
239 optional arg 'onerror' is specified, it should be a function; it
240 will be called with one argument, an os.error instance. It can
241 report the error to continue with the walk, or raise the exception
242 to abort the walk. Note that the filename is available as the
243 filename attribute of the exception object.
245 By default, os.walk does not follow symbolic links to subdirectories on
246 systems that support them. In order to get this functionality, set the
247 optional argument 'followlinks' to true.
249 Caution: if you pass a relative pathname for top, don't change the
250 current working directory between resumptions of walk. walk never
251 changes the current directory, and assumes that the client doesn't
252 either.
254 Example:
256 import os
257 from os.path import join, getsize
258 for root, dirs, files in os.walk('python/Lib/email'):
259 print root, "consumes",
260 print sum([getsize(join(root, name)) for name in files]),
261 print "bytes in", len(files), "non-directory files"
262 if 'CVS' in dirs:
263 dirs.remove('CVS') # don't visit CVS directories
266 islink, join, isdir = path.islink, path.join, path.isdir
268 # We may not have read permission for top, in which case we can't
269 # get a list of the files the directory contains. os.path.walk
270 # always suppressed the exception then, rather than blow up for a
271 # minor reason when (say) a thousand readable directories are still
272 # left to visit. That logic is copied here.
273 try:
274 # Note that listdir and error are globals in this module due
275 # to earlier import-*.
276 names = listdir(top)
277 except error, err:
278 if onerror is not None:
279 onerror(err)
280 return
282 dirs, nondirs = [], []
283 for name in names:
284 if isdir(join(top, name)):
285 dirs.append(name)
286 else:
287 nondirs.append(name)
289 if topdown:
290 yield top, dirs, nondirs
291 for name in dirs:
292 new_path = join(top, name)
293 if followlinks or not islink(new_path):
294 for x in walk(new_path, topdown, onerror, followlinks):
295 yield x
296 if not topdown:
297 yield top, dirs, nondirs
299 __all__.append("walk")
301 # Make sure os.environ exists, at least
302 try:
303 environ
304 except NameError:
305 environ = {}
307 def execl(file, *args):
308 """execl(file, *args)
310 Execute the executable file with argument list args, replacing the
311 current process. """
312 execv(file, args)
314 def execle(file, *args):
315 """execle(file, *args, env)
317 Execute the executable file with argument list args and
318 environment env, replacing the current process. """
319 env = args[-1]
320 execve(file, args[:-1], env)
322 def execlp(file, *args):
323 """execlp(file, *args)
325 Execute the executable file (which is searched for along $PATH)
326 with argument list args, replacing the current process. """
327 execvp(file, args)
329 def execlpe(file, *args):
330 """execlpe(file, *args, env)
332 Execute the executable file (which is searched for along $PATH)
333 with argument list args and environment env, replacing the current
334 process. """
335 env = args[-1]
336 execvpe(file, args[:-1], env)
338 def execvp(file, args):
339 """execp(file, args)
341 Execute the executable file (which is searched for along $PATH)
342 with argument list args, replacing the current process.
343 args may be a list or tuple of strings. """
344 _execvpe(file, args)
346 def execvpe(file, args, env):
347 """execvpe(file, args, env)
349 Execute the executable file (which is searched for along $PATH)
350 with argument list args and environment env , replacing the
351 current process.
352 args may be a list or tuple of strings. """
353 _execvpe(file, args, env)
355 __all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"])
357 def _execvpe(file, args, env=None):
358 if env is not None:
359 func = execve
360 argrest = (args, env)
361 else:
362 func = execv
363 argrest = (args,)
364 env = environ
366 head, tail = path.split(file)
367 if head:
368 func(file, *argrest)
369 return
370 if 'PATH' in env:
371 envpath = env['PATH']
372 else:
373 envpath = defpath
374 PATH = envpath.split(pathsep)
375 saved_exc = None
376 saved_tb = None
377 for dir in PATH:
378 fullname = path.join(dir, file)
379 try:
380 func(fullname, *argrest)
381 except error, e:
382 tb = sys.exc_info()[2]
383 if (e.errno != errno.ENOENT and e.errno != errno.ENOTDIR
384 and saved_exc is None):
385 saved_exc = e
386 saved_tb = tb
387 if saved_exc:
388 raise error, saved_exc, saved_tb
389 raise error, e, tb
391 # Change environ to automatically call putenv() if it exists
392 try:
393 # This will fail if there's no putenv
394 putenv
395 except NameError:
396 pass
397 else:
398 import UserDict
400 # Fake unsetenv() for Windows
401 # not sure about os2 here but
402 # I'm guessing they are the same.
404 if name in ('os2', 'nt'):
405 def unsetenv(key):
406 putenv(key, "")
408 if name == "riscos":
409 # On RISC OS, all env access goes through getenv and putenv
410 from riscosenviron import _Environ
411 elif name in ('os2', 'nt'): # Where Env Var Names Must Be UPPERCASE
412 # But we store them as upper case
413 class _Environ(UserDict.IterableUserDict):
414 def __init__(self, environ):
415 UserDict.UserDict.__init__(self)
416 data = self.data
417 for k, v in environ.items():
418 data[k.upper()] = v
419 def __setitem__(self, key, item):
420 putenv(key, item)
421 self.data[key.upper()] = item
422 def __getitem__(self, key):
423 return self.data[key.upper()]
424 try:
425 unsetenv
426 except NameError:
427 def __delitem__(self, key):
428 del self.data[key.upper()]
429 else:
430 def __delitem__(self, key):
431 unsetenv(key)
432 del self.data[key.upper()]
433 def clear(self):
434 for key in self.data.keys():
435 unsetenv(key)
436 del self.data[key]
437 def pop(self, key, *args):
438 unsetenv(key)
439 return self.data.pop(key.upper(), *args)
440 def has_key(self, key):
441 return key.upper() in self.data
442 def __contains__(self, key):
443 return key.upper() in self.data
444 def get(self, key, failobj=None):
445 return self.data.get(key.upper(), failobj)
446 def update(self, dict=None, **kwargs):
447 if dict:
448 try:
449 keys = dict.keys()
450 except AttributeError:
451 # List of (key, value)
452 for k, v in dict:
453 self[k] = v
454 else:
455 # got keys
456 # cannot use items(), since mappings
457 # may not have them.
458 for k in keys:
459 self[k] = dict[k]
460 if kwargs:
461 self.update(kwargs)
462 def copy(self):
463 return dict(self)
465 else: # Where Env Var Names Can Be Mixed Case
466 class _Environ(UserDict.IterableUserDict):
467 def __init__(self, environ):
468 UserDict.UserDict.__init__(self)
469 self.data = environ
470 def __setitem__(self, key, item):
471 putenv(key, item)
472 self.data[key] = item
473 def update(self, dict=None, **kwargs):
474 if dict:
475 try:
476 keys = dict.keys()
477 except AttributeError:
478 # List of (key, value)
479 for k, v in dict:
480 self[k] = v
481 else:
482 # got keys
483 # cannot use items(), since mappings
484 # may not have them.
485 for k in keys:
486 self[k] = dict[k]
487 if kwargs:
488 self.update(kwargs)
489 try:
490 unsetenv
491 except NameError:
492 pass
493 else:
494 def __delitem__(self, key):
495 unsetenv(key)
496 del self.data[key]
497 def clear(self):
498 for key in self.data.keys():
499 unsetenv(key)
500 del self.data[key]
501 def pop(self, key, *args):
502 unsetenv(key)
503 return self.data.pop(key, *args)
504 def copy(self):
505 return dict(self)
508 environ = _Environ(environ)
510 def getenv(key, default=None):
511 """Get an environment variable, return None if it doesn't exist.
512 The optional second argument can specify an alternate default."""
513 return environ.get(key, default)
514 __all__.append("getenv")
516 def _exists(name):
517 return name in globals()
519 # Supply spawn*() (probably only for Unix)
520 if _exists("fork") and not _exists("spawnv") and _exists("execv"):
522 P_WAIT = 0
523 P_NOWAIT = P_NOWAITO = 1
525 # XXX Should we support P_DETACH? I suppose it could fork()**2
526 # and close the std I/O streams. Also, P_OVERLAY is the same
527 # as execv*()?
529 def _spawnvef(mode, file, args, env, func):
530 # Internal helper; func is the exec*() function to use
531 pid = fork()
532 if not pid:
533 # Child
534 try:
535 if env is None:
536 func(file, args)
537 else:
538 func(file, args, env)
539 except:
540 _exit(127)
541 else:
542 # Parent
543 if mode == P_NOWAIT:
544 return pid # Caller is responsible for waiting!
545 while 1:
546 wpid, sts = waitpid(pid, 0)
547 if WIFSTOPPED(sts):
548 continue
549 elif WIFSIGNALED(sts):
550 return -WTERMSIG(sts)
551 elif WIFEXITED(sts):
552 return WEXITSTATUS(sts)
553 else:
554 raise error, "Not stopped, signaled or exited???"
556 def spawnv(mode, file, args):
557 """spawnv(mode, file, args) -> integer
559 Execute file with arguments from args in a subprocess.
560 If mode == P_NOWAIT return the pid of the process.
561 If mode == P_WAIT return the process's exit code if it exits normally;
562 otherwise return -SIG, where SIG is the signal that killed it. """
563 return _spawnvef(mode, file, args, None, execv)
565 def spawnve(mode, file, args, env):
566 """spawnve(mode, file, args, env) -> integer
568 Execute file with arguments from args in a subprocess with the
569 specified environment.
570 If mode == P_NOWAIT return the pid of the process.
571 If mode == P_WAIT return the process's exit code if it exits normally;
572 otherwise return -SIG, where SIG is the signal that killed it. """
573 return _spawnvef(mode, file, args, env, execve)
575 # Note: spawnvp[e] is't currently supported on Windows
577 def spawnvp(mode, file, args):
578 """spawnvp(mode, file, args) -> integer
580 Execute file (which is looked for along $PATH) with arguments from
581 args in a subprocess.
582 If mode == P_NOWAIT return the pid of the process.
583 If mode == P_WAIT return the process's exit code if it exits normally;
584 otherwise return -SIG, where SIG is the signal that killed it. """
585 return _spawnvef(mode, file, args, None, execvp)
587 def spawnvpe(mode, file, args, env):
588 """spawnvpe(mode, file, args, env) -> integer
590 Execute file (which is looked for along $PATH) with arguments from
591 args in a subprocess with the supplied environment.
592 If mode == P_NOWAIT return the pid of the process.
593 If mode == P_WAIT return the process's exit code if it exits normally;
594 otherwise return -SIG, where SIG is the signal that killed it. """
595 return _spawnvef(mode, file, args, env, execvpe)
597 if _exists("spawnv"):
598 # These aren't supplied by the basic Windows code
599 # but can be easily implemented in Python
601 def spawnl(mode, file, *args):
602 """spawnl(mode, file, *args) -> integer
604 Execute file with arguments from args in a subprocess.
605 If mode == P_NOWAIT return the pid of the process.
606 If mode == P_WAIT return the process's exit code if it exits normally;
607 otherwise return -SIG, where SIG is the signal that killed it. """
608 return spawnv(mode, file, args)
610 def spawnle(mode, file, *args):
611 """spawnle(mode, file, *args, env) -> integer
613 Execute file with arguments from args in a subprocess with the
614 supplied environment.
615 If mode == P_NOWAIT return the pid of the process.
616 If mode == P_WAIT return the process's exit code if it exits normally;
617 otherwise return -SIG, where SIG is the signal that killed it. """
618 env = args[-1]
619 return spawnve(mode, file, args[:-1], env)
622 __all__.extend(["spawnv", "spawnve", "spawnl", "spawnle",])
625 if _exists("spawnvp"):
626 # At the moment, Windows doesn't implement spawnvp[e],
627 # so it won't have spawnlp[e] either.
628 def spawnlp(mode, file, *args):
629 """spawnlp(mode, file, *args) -> integer
631 Execute file (which is looked for along $PATH) with arguments from
632 args in a subprocess with the supplied environment.
633 If mode == P_NOWAIT return the pid of the process.
634 If mode == P_WAIT return the process's exit code if it exits normally;
635 otherwise return -SIG, where SIG is the signal that killed it. """
636 return spawnvp(mode, file, args)
638 def spawnlpe(mode, file, *args):
639 """spawnlpe(mode, file, *args, env) -> integer
641 Execute file (which is looked for along $PATH) with arguments from
642 args in a subprocess with the supplied environment.
643 If mode == P_NOWAIT return the pid of the process.
644 If mode == P_WAIT return the process's exit code if it exits normally;
645 otherwise return -SIG, where SIG is the signal that killed it. """
646 env = args[-1]
647 return spawnvpe(mode, file, args[:-1], env)
650 __all__.extend(["spawnvp", "spawnvpe", "spawnlp", "spawnlpe",])
653 # Supply popen2 etc. (for Unix)
654 if _exists("fork"):
655 if not _exists("popen2"):
656 def popen2(cmd, mode="t", bufsize=-1):
657 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd'
658 may be a sequence, in which case arguments will be passed directly to
659 the program without shell intervention (as with os.spawnv()). If 'cmd'
660 is a string it will be passed to the shell (as with os.system()). If
661 'bufsize' is specified, it sets the buffer size for the I/O pipes. The
662 file objects (child_stdin, child_stdout) are returned."""
663 import warnings
664 msg = "os.popen2 is deprecated. Use the subprocess module."
665 warnings.warn(msg, DeprecationWarning, stacklevel=2)
667 import subprocess
668 PIPE = subprocess.PIPE
669 p = subprocess.Popen(cmd, shell=isinstance(cmd, basestring),
670 bufsize=bufsize, stdin=PIPE, stdout=PIPE,
671 close_fds=True)
672 return p.stdin, p.stdout
673 __all__.append("popen2")
675 if not _exists("popen3"):
676 def popen3(cmd, mode="t", bufsize=-1):
677 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd'
678 may be a sequence, in which case arguments will be passed directly to
679 the program without shell intervention (as with os.spawnv()). If 'cmd'
680 is a string it will be passed to the shell (as with os.system()). If
681 'bufsize' is specified, it sets the buffer size for the I/O pipes. The
682 file objects (child_stdin, child_stdout, child_stderr) are returned."""
683 import warnings
684 msg = "os.popen3 is deprecated. Use the subprocess module."
685 warnings.warn(msg, DeprecationWarning, stacklevel=2)
687 import subprocess
688 PIPE = subprocess.PIPE
689 p = subprocess.Popen(cmd, shell=isinstance(cmd, basestring),
690 bufsize=bufsize, stdin=PIPE, stdout=PIPE,
691 stderr=PIPE, close_fds=True)
692 return p.stdin, p.stdout, p.stderr
693 __all__.append("popen3")
695 if not _exists("popen4"):
696 def popen4(cmd, mode="t", bufsize=-1):
697 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd'
698 may be a sequence, in which case arguments will be passed directly to
699 the program without shell intervention (as with os.spawnv()). If 'cmd'
700 is a string it will be passed to the shell (as with os.system()). If
701 'bufsize' is specified, it sets the buffer size for the I/O pipes. The
702 file objects (child_stdin, child_stdout_stderr) are returned."""
703 import warnings
704 msg = "os.popen4 is deprecated. Use the subprocess module."
705 warnings.warn(msg, DeprecationWarning, stacklevel=2)
707 import subprocess
708 PIPE = subprocess.PIPE
709 p = subprocess.Popen(cmd, shell=isinstance(cmd, basestring),
710 bufsize=bufsize, stdin=PIPE, stdout=PIPE,
711 stderr=subprocess.STDOUT, close_fds=True)
712 return p.stdin, p.stdout
713 __all__.append("popen4")
715 import copy_reg as _copy_reg
717 def _make_stat_result(tup, dict):
718 return stat_result(tup, dict)
720 def _pickle_stat_result(sr):
721 (type, args) = sr.__reduce__()
722 return (_make_stat_result, args)
724 try:
725 _copy_reg.pickle(stat_result, _pickle_stat_result, _make_stat_result)
726 except NameError: # stat_result may not exist
727 pass
729 def _make_statvfs_result(tup, dict):
730 return statvfs_result(tup, dict)
732 def _pickle_statvfs_result(sr):
733 (type, args) = sr.__reduce__()
734 return (_make_statvfs_result, args)
736 try:
737 _copy_reg.pickle(statvfs_result, _pickle_statvfs_result,
738 _make_statvfs_result)
739 except NameError: # statvfs_result may not exist
740 pass
742 if not _exists("urandom"):
743 def urandom(n):
744 """urandom(n) -> str
746 Return a string of n random bytes suitable for cryptographic use.
749 try:
750 _urandomfd = open("/dev/urandom", O_RDONLY)
751 except (OSError, IOError):
752 raise NotImplementedError("/dev/urandom (or equivalent) not found")
753 try:
754 bs = b""
755 while n - len(bs) >= 1:
756 bs += read(_urandomfd, n - len(bs))
757 finally:
758 close(_urandomfd)
759 return bs