| """Temporary files. |
| |
| This module provides generic, low- and high-level interfaces for |
| creating temporary files and directories. The interfaces listed |
| as "safe" just below can be used without fear of race conditions. |
| Those listed as "unsafe" cannot, and are provided for backward |
| compatibility only. |
| |
| This module also provides some data items to the user: |
| |
| TMP_MAX - maximum number of names that will be tried before |
| giving up. |
| template - the default prefix for all temporary names. |
| You may change this to control the default prefix. |
| tempdir - If this is set to a string before the first use of |
| any routine from this module, it will be considered as |
| another candidate location to store temporary files. |
| """ |
| |
| __all__ = [ |
| "NamedTemporaryFile", "TemporaryFile", # high level safe interfaces |
| "mkstemp", "mkdtemp", # low level safe interfaces |
| "mktemp", # deprecated unsafe interface |
| "TMP_MAX", "gettempprefix", # constants |
| "tempdir", "gettempdir" |
| ] |
| |
| |
| # Imports. |
| |
| import os as _os |
| import errno as _errno |
| from random import Random as _Random |
| |
| if _os.name == 'mac': |
| import Carbon.Folder as _Folder |
| import Carbon.Folders as _Folders |
| |
| try: |
| import fcntl as _fcntl |
| except ImportError: |
| def _set_cloexec(fd): |
| pass |
| else: |
| def _set_cloexec(fd): |
| try: |
| flags = _fcntl.fcntl(fd, _fcntl.F_GETFD, 0) |
| except IOError: |
| pass |
| else: |
| # flags read successfully, modify |
| flags |= _fcntl.FD_CLOEXEC |
| _fcntl.fcntl(fd, _fcntl.F_SETFD, flags) |
| |
| |
| try: |
| import thread as _thread |
| except ImportError: |
| import dummy_thread as _thread |
| _allocate_lock = _thread.allocate_lock |
| |
| _text_openflags = _os.O_RDWR | _os.O_CREAT | _os.O_EXCL |
| if hasattr(_os, 'O_NOINHERIT'): |
| _text_openflags |= _os.O_NOINHERIT |
| if hasattr(_os, 'O_NOFOLLOW'): |
| _text_openflags |= _os.O_NOFOLLOW |
| |
| _bin_openflags = _text_openflags |
| if hasattr(_os, 'O_BINARY'): |
| _bin_openflags |= _os.O_BINARY |
| |
| if hasattr(_os, 'TMP_MAX'): |
| TMP_MAX = _os.TMP_MAX |
| else: |
| TMP_MAX = 10000 |
| |
| template = "tmp" |
| |
| tempdir = None |
| |
| # Internal routines. |
| |
| _once_lock = _allocate_lock() |
| |
| if hasattr(_os, "lstat"): |
| _stat = _os.lstat |
| elif hasattr(_os, "stat"): |
| _stat = _os.stat |
| else: |
| # Fallback. All we need is something that raises os.error if the |
| # file doesn't exist. |
| def _stat(fn): |
| try: |
| f = open(fn) |
| except IOError: |
| raise _os.error |
| f.close() |
| |
| def _exists(fn): |
| try: |
| _stat(fn) |
| except _os.error: |
| return False |
| else: |
| return True |
| |
| class _RandomNameSequence: |
| """An instance of _RandomNameSequence generates an endless |
| sequence of unpredictable strings which can safely be incorporated |
| into file names. Each string is six characters long. Multiple |
| threads can safely use the same instance at the same time. |
| |
| _RandomNameSequence is an iterator.""" |
| |
| characters = ("abcdefghijklmnopqrstuvwxyz" + |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + |
| "0123456789-_") |
| |
| def __init__(self): |
| self.mutex = _allocate_lock() |
| self.rng = _Random() |
| self.normcase = _os.path.normcase |
| |
| def __iter__(self): |
| return self |
| |
| def next(self): |
| m = self.mutex |
| c = self.characters |
| choose = self.rng.choice |
| |
| m.acquire() |
| try: |
| letters = [choose(c) for dummy in "123456"] |
| finally: |
| m.release() |
| |
| return self.normcase(''.join(letters)) |
| |
| def _candidate_tempdir_list(): |
| """Generate a list of candidate temporary directories which |
| _get_default_tempdir will try.""" |
| |
| dirlist = [] |
| |
| # First, try the environment. |
| for envname in 'TMPDIR', 'TEMP', 'TMP': |
| dirname = _os.getenv(envname) |
| if dirname: dirlist.append(dirname) |
| |
| # Failing that, try OS-specific locations. |
| if _os.name == 'mac': |
| try: |
| fsr = _Folder.FSFindFolder(_Folders.kOnSystemDisk, |
| _Folders.kTemporaryFolderType, 1) |
| dirname = fsr.as_pathname() |
| dirlist.append(dirname) |
| except _Folder.error: |
| pass |
| elif _os.name == 'riscos': |
| dirname = _os.getenv('Wimp$ScrapDir') |
| if dirname: dirlist.append(dirname) |
| elif _os.name == 'nt': |
| dirlist.extend([ r'c:\temp', r'c:\tmp', r'\temp', r'\tmp' ]) |
| else: |
| dirlist.extend([ '/tmp', '/var/tmp', '/usr/tmp' ]) |
| |
| # As a last resort, the current directory. |
| try: |
| dirlist.append(_os.getcwd()) |
| except (AttributeError, _os.error): |
| dirlist.append(_os.curdir) |
| |
| return dirlist |
| |
| def _get_default_tempdir(): |
| """Calculate the default directory to use for temporary files. |
| This routine should be called exactly once. |
| |
| We determine whether or not a candidate temp dir is usable by |
| trying to create and write to a file in that directory. If this |
| is successful, the test file is deleted. To prevent denial of |
| service, the name of the test file must be randomized.""" |
| |
| namer = _RandomNameSequence() |
| dirlist = _candidate_tempdir_list() |
| flags = _text_openflags |
| |
| for dir in dirlist: |
| if dir != _os.curdir: |
| dir = _os.path.normcase(_os.path.abspath(dir)) |
| # Try only a few names per directory. |
| for seq in xrange(100): |
| name = namer.next() |
| filename = _os.path.join(dir, name) |
| try: |
| fd = _os.open(filename, flags, 0600) |
| fp = _os.fdopen(fd, 'w') |
| fp.write('blat') |
| fp.close() |
| _os.unlink(filename) |
| del fp, fd |
| return dir |
| except (OSError, IOError), e: |
| if e[0] != _errno.EEXIST: |
| break # no point trying more names in this directory |
| pass |
| raise IOError, (_errno.ENOENT, |
| ("No usable temporary directory found in %s" % dirlist)) |
| |
| _name_sequence = None |
| |
| def _get_candidate_names(): |
| """Common setup sequence for all user-callable interfaces.""" |
| |
| global _name_sequence |
| if _name_sequence is None: |
| _once_lock.acquire() |
| try: |
| if _name_sequence is None: |
| _name_sequence = _RandomNameSequence() |
| finally: |
| _once_lock.release() |
| return _name_sequence |
| |
| |
| def _mkstemp_inner(dir, pre, suf, flags): |
| """Code common to mkstemp, TemporaryFile, and NamedTemporaryFile.""" |
| |
| names = _get_candidate_names() |
| |
| for seq in xrange(TMP_MAX): |
| name = names.next() |
| file = _os.path.join(dir, pre + name + suf) |
| try: |
| fd = _os.open(file, flags, 0600) |
| _set_cloexec(fd) |
| return (fd, _os.path.abspath(file)) |
| except OSError, e: |
| if e.errno == _errno.EEXIST: |
| continue # try again |
| raise |
| |
| raise IOError, (_errno.EEXIST, "No usable temporary file name found") |
| |
| |
| # User visible interfaces. |
| |
| def gettempprefix(): |
| """Accessor for tempdir.template.""" |
| return template |
| |
| tempdir = None |
| |
| def gettempdir(): |
| """Accessor for tempdir.tempdir.""" |
| global tempdir |
| if tempdir is None: |
| _once_lock.acquire() |
| try: |
| if tempdir is None: |
| tempdir = _get_default_tempdir() |
| finally: |
| _once_lock.release() |
| return tempdir |
| |
| def mkstemp(suffix="", prefix=template, dir=None, text=False): |
| """mkstemp([suffix, [prefix, [dir, [text]]]]) |
| User-callable function to create and return a unique temporary |
| file. The return value is a pair (fd, name) where fd is the |
| file descriptor returned by os.open, and name is the filename. |
| |
| If 'suffix' is specified, the file name will end with that suffix, |
| otherwise there will be no suffix. |
| |
| If 'prefix' is specified, the file name will begin with that prefix, |
| otherwise a default prefix is used. |
| |
| If 'dir' is specified, the file will be created in that directory, |
| otherwise a default directory is used. |
| |
| If 'text' is specified and true, the file is opened in text |
| mode. Else (the default) the file is opened in binary mode. On |
| some operating systems, this makes no difference. |
| |
| The file is readable and writable only by the creating user ID. |
| If the operating system uses permission bits to indicate whether a |
| file is executable, the file is executable by no one. The file |
| descriptor is not inherited by children of this process. |
| |
| Caller is responsible for deleting the file when done with it. |
| """ |
| |
| if dir is None: |
| dir = gettempdir() |
| |
| if text: |
| flags = _text_openflags |
| else: |
| flags = _bin_openflags |
| |
| return _mkstemp_inner(dir, prefix, suffix, flags) |
| |
| |
| def mkdtemp(suffix="", prefix=template, dir=None): |
| """mkdtemp([suffix, [prefix, [dir]]]) |
| User-callable function to create and return a unique temporary |
| directory. The return value is the pathname of the directory. |
| |
| Arguments are as for mkstemp, except that the 'text' argument is |
| not accepted. |
| |
| The directory is readable, writable, and searchable only by the |
| creating user. |
| |
| Caller is responsible for deleting the directory when done with it. |
| """ |
| |
| if dir is None: |
| dir = gettempdir() |
| |
| names = _get_candidate_names() |
| |
| for seq in xrange(TMP_MAX): |
| name = names.next() |
| file = _os.path.join(dir, prefix + name + suffix) |
| try: |
| _os.mkdir(file, 0700) |
| return file |
| except OSError, e: |
| if e.errno == _errno.EEXIST: |
| continue # try again |
| raise |
| |
| raise IOError, (_errno.EEXIST, "No usable temporary directory name found") |
| |
| def mktemp(suffix="", prefix=template, dir=None): |
| """mktemp([suffix, [prefix, [dir]]]) |
| User-callable function to return a unique temporary file name. The |
| file is not created. |
| |
| Arguments are as for mkstemp, except that the 'text' argument is |
| not accepted. |
| |
| This function is unsafe and should not be used. The file name |
| refers to a file that did not exist at some point, but by the time |
| you get around to creating it, someone else may have beaten you to |
| the punch. |
| """ |
| |
| ## from warnings import warn as _warn |
| ## _warn("mktemp is a potential security risk to your program", |
| ## RuntimeWarning, stacklevel=2) |
| |
| if dir is None: |
| dir = gettempdir() |
| |
| names = _get_candidate_names() |
| for seq in xrange(TMP_MAX): |
| name = names.next() |
| file = _os.path.join(dir, prefix + name + suffix) |
| if not _exists(file): |
| return file |
| |
| raise IOError, (_errno.EEXIST, "No usable temporary filename found") |
| |
| class _TemporaryFileWrapper: |
| """Temporary file wrapper |
| |
| This class provides a wrapper around files opened for |
| temporary use. In particular, it seeks to automatically |
| remove the file when it is no longer needed. |
| """ |
| |
| def __init__(self, file, name): |
| self.file = file |
| self.name = name |
| self.close_called = False |
| |
| def __getattr__(self, name): |
| file = self.__dict__['file'] |
| a = getattr(file, name) |
| if type(a) != type(0): |
| setattr(self, name, a) |
| return a |
| |
| # NT provides delete-on-close as a primitive, so we don't need |
| # the wrapper to do anything special. We still use it so that |
| # file.name is useful (i.e. not "(fdopen)") with NamedTemporaryFile. |
| if _os.name != 'nt': |
| |
| # Cache the unlinker so we don't get spurious errors at |
| # shutdown when the module-level "os" is None'd out. Note |
| # that this must be referenced as self.unlink, because the |
| # name TemporaryFileWrapper may also get None'd out before |
| # __del__ is called. |
| unlink = _os.unlink |
| |
| def close(self): |
| if not self.close_called: |
| self.close_called = True |
| self.file.close() |
| self.unlink(self.name) |
| |
| def __del__(self): |
| self.close() |
| |
| def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="", |
| prefix=template, dir=None): |
| """Create and return a temporary file. |
| Arguments: |
| 'prefix', 'suffix', 'dir' -- as for mkstemp. |
| 'mode' -- the mode argument to os.fdopen (default "w+b"). |
| 'bufsize' -- the buffer size argument to os.fdopen (default -1). |
| The file is created as mkstemp() would do it. |
| |
| Returns a file object; the name of the file is accessible as |
| file.name. The file will be automatically deleted when it is |
| closed. |
| """ |
| |
| if dir is None: |
| dir = gettempdir() |
| |
| if 'b' in mode: |
| flags = _bin_openflags |
| else: |
| flags = _text_openflags |
| |
| # Setting O_TEMPORARY in the flags causes the OS to delete |
| # the file when it is closed. This is only supported by Windows. |
| if _os.name == 'nt': |
| flags |= _os.O_TEMPORARY |
| |
| (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags) |
| file = _os.fdopen(fd, mode, bufsize) |
| return _TemporaryFileWrapper(file, name) |
| |
| if _os.name != 'posix' or _os.sys.platform == 'cygwin': |
| # On non-POSIX and Cygwin systems, assume that we cannot unlink a file |
| # while it is open. |
| TemporaryFile = NamedTemporaryFile |
| |
| else: |
| def TemporaryFile(mode='w+b', bufsize=-1, suffix="", |
| prefix=template, dir=None): |
| """Create and return a temporary file. |
| Arguments: |
| 'prefix', 'suffix', 'directory' -- as for mkstemp. |
| 'mode' -- the mode argument to os.fdopen (default "w+b"). |
| 'bufsize' -- the buffer size argument to os.fdopen (default -1). |
| The file is created as mkstemp() would do it. |
| |
| Returns a file object. The file has no name, and will cease to |
| exist when it is closed. |
| """ |
| |
| if dir is None: |
| dir = gettempdir() |
| |
| if 'b' in mode: |
| flags = _bin_openflags |
| else: |
| flags = _text_openflags |
| |
| (fd, name) = _mkstemp_inner(dir, prefix, suffix, flags) |
| try: |
| _os.unlink(name) |
| return _os.fdopen(fd, mode, bufsize) |
| except: |
| _os.close(fd) |
| raise |