mirror of
git://projects.qi-hardware.com/openwrt-packages.git
synced 2024-11-18 20:30:17 +02:00
604 lines
17 KiB
Python
604 lines
17 KiB
Python
"""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
|
|
"SpooledTemporaryFile",
|
|
"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
|
|
|
|
try:
|
|
from cStringIO import StringIO as _StringIO
|
|
except ImportError:
|
|
from StringIO import StringIO as _StringIO
|
|
|
|
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"
|
|
|
|
# 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 == '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 tempfile.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):
|
|
"""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):
|
|
"""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):
|
|
"""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, delete=True):
|
|
self.file = file
|
|
self.name = name
|
|
self.close_called = False
|
|
self.delete = delete
|
|
|
|
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 not issubclass(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()
|
|
if self.delete:
|
|
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, delete=True):
|
|
"""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).
|
|
'delete' -- whether the file is deleted on close (default True).
|
|
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 unless the 'delete' argument is set to False.
|
|
"""
|
|
|
|
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' and delete:
|
|
flags |= _os.O_TEMPORARY
|
|
|
|
(fd, name) = _mkstemp_inner(dir, prefix, suffix, flags)
|
|
file = _os.fdopen(fd, mode, bufsize)
|
|
return _TemporaryFileWrapper(file, name, delete)
|
|
|
|
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
|
|
|
|
class SpooledTemporaryFile:
|
|
"""Temporary file wrapper, specialized to switch from
|
|
StringIO to a real file when it exceeds a certain size or
|
|
when a fileno is needed.
|
|
"""
|
|
_rolled = False
|
|
|
|
def __init__(self, max_size=0, mode='w+b', bufsize=-1,
|
|
suffix="", prefix=template, dir=None):
|
|
self._file = _StringIO()
|
|
self._max_size = max_size
|
|
self._rolled = False
|
|
self._TemporaryFileArgs = (mode, bufsize, suffix, prefix, dir)
|
|
|
|
def _check(self, file):
|
|
if self._rolled: return
|
|
max_size = self._max_size
|
|
if max_size and file.tell() > max_size:
|
|
self.rollover()
|
|
|
|
def rollover(self):
|
|
if self._rolled: return
|
|
file = self._file
|
|
newfile = self._file = TemporaryFile(*self._TemporaryFileArgs)
|
|
del self._TemporaryFileArgs
|
|
|
|
newfile.write(file.getvalue())
|
|
newfile.seek(file.tell(), 0)
|
|
|
|
self._rolled = True
|
|
|
|
# The method caching trick from NamedTemporaryFile
|
|
# won't work here, because _file may change from a
|
|
# _StringIO instance to a real file. So we list
|
|
# all the methods directly.
|
|
|
|
# Context management protocol
|
|
def __enter__(self):
|
|
if self._file.closed:
|
|
raise ValueError("Cannot enter context with closed file")
|
|
return self
|
|
|
|
def __exit__(self, exc, value, tb):
|
|
self._file.close()
|
|
|
|
# file protocol
|
|
def __iter__(self):
|
|
return self._file.__iter__()
|
|
|
|
def close(self):
|
|
self._file.close()
|
|
|
|
@property
|
|
def closed(self):
|
|
return self._file.closed
|
|
|
|
@property
|
|
def encoding(self):
|
|
return self._file.encoding
|
|
|
|
def fileno(self):
|
|
self.rollover()
|
|
return self._file.fileno()
|
|
|
|
def flush(self):
|
|
self._file.flush()
|
|
|
|
def isatty(self):
|
|
return self._file.isatty()
|
|
|
|
@property
|
|
def mode(self):
|
|
return self._file.mode
|
|
|
|
@property
|
|
def name(self):
|
|
return self._file.name
|
|
|
|
@property
|
|
def newlines(self):
|
|
return self._file.newlines
|
|
|
|
def next(self):
|
|
return self._file.next
|
|
|
|
def read(self, *args):
|
|
return self._file.read(*args)
|
|
|
|
def readline(self, *args):
|
|
return self._file.readline(*args)
|
|
|
|
def readlines(self, *args):
|
|
return self._file.readlines(*args)
|
|
|
|
def seek(self, *args):
|
|
self._file.seek(*args)
|
|
|
|
@property
|
|
def softspace(self):
|
|
return self._file.softspace
|
|
|
|
def tell(self):
|
|
return self._file.tell()
|
|
|
|
def truncate(self):
|
|
self._file.truncate()
|
|
|
|
def write(self, s):
|
|
file = self._file
|
|
rv = file.write(s)
|
|
self._check(file)
|
|
return rv
|
|
|
|
def writelines(self, iterable):
|
|
file = self._file
|
|
rv = file.writelines(iterable)
|
|
self._check(file)
|
|
return rv
|
|
|
|
def xreadlines(self, *args):
|
|
return self._file.xreadlines(*args)
|