python-2.5.2/win32/Lib/tempfile.py
changeset 0 ae805ac0140d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python-2.5.2/win32/Lib/tempfile.py	Fri Apr 03 17:19:34 2009 +0100
@@ -0,0 +1,488 @@
+"""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):
+        # Attribute lookups are delegated to the underlying file
+        # and cached for non-numeric results
+        # (i.e. methods are cached, closed and friends are not)
+        file = self.__dict__['file']
+        a = getattr(file, name)
+        if type(a) != type(0):
+            setattr(self, name, a)
+        return a
+
+    # The underlying __enter__ method returns the wrong object
+    # (self.file) so override it to return the wrapper
+    def __enter__(self):
+        self.file.__enter__()
+        return self
+
+    # 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()
+
+        # Need to trap __exit__ as well to ensure the file gets
+        # deleted when used in a with statement
+        def __exit__(self, exc, value, tb):
+            result = self.file.__exit__(exc, value, tb)
+            self.close()
+            return result
+
+
+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 an object with a file-like interface; 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', '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 an object with a file-like interface.  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