save project

func.py

-
+import tabnanny
 
 
 
 
 
 

x2.py

+r"""OS routines for NT or Posix depending on what system we're on.
+
+This exports:
+  - all functions from posix or nt, e.g. unlink, stat, etc.
+  - os.path is either posixpath or ntpath
+  - os.name is either 'posix' or 'nt'
+  - os.curdir is a string representing the current directory (always '.')
+  - os.pardir is a string representing the parent directory (always '..')
+  - os.sep is the (or a most common) pathname separator ('/' or '\\')
+  - os.extsep is the extension separator (always '.')
+  - os.altsep is the alternate pathname separator (None or '/')
+  - os.pathsep is the component separator used in $PATH etc
+  - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
+  - os.defpath is the default search path for executables
+  - os.devnull is the file path of the null device ('/dev/null', etc.)
+
+Programs that import and use 'os' stand a better chance of being
+portable between different platforms.  Of course, they must then
+only use functions that are defined by all platforms (e.g., unlink
+and opendir), and leave all pathname manipulation to os.path
+(e.g., split and join).
+"""
+
+#'
+import abc
+import sys
+import stat as st
+
+_names = sys.builtin_module_names
+
+# Note:  more names are added to __all__ later.
+__all__ = ["altsep", "curdir", "pardir", "sep", "pathsep", "linesep",
+           "defpath", "name", "path", "devnull", "SEEK_SET", "SEEK_CUR",
+           "SEEK_END", "fsencode", "fsdecode", "get_exec_path", "fdopen",
+           "popen", "extsep"]
+
+def _exists(name):
+    return name in globals()
+
+def _get_exports_list(module):
+    try:
+        return list(module.__all__)
+    except AttributeError:
+        return [n for n in dir(module) if n[0] != '_']
+
+# Any new dependencies of the os module and/or changes in path separator
+# requires updating importlib as well.
+if 'posix' in _names:
+    name = 'posix'
+    linesep = '\n'
+    from posix import *
+    try:
+        from posix import _exit
+        __all__.append('_exit')
+    except ImportError:
+        pass
+    import posixpath as path
+
+    try:
+        from posix import _have_functions
+    except ImportError:
+        pass
+
+    import posix
+    __all__.extend(_get_exports_list(posix))
+    del posix
+
+elif 'nt' in _names:
+    name = 'nt'
+    linesep = '\r\n'
+    from nt import *
+    try:
+        from nt import _exit
+        __all__.append('_exit')
+    except ImportError:
+        pass
+    import ntpath as path
+
+    import nt
+    __all__.extend(_get_exports_list(nt))
+    del nt
+
+    try:
+        from nt import _have_functions
+    except ImportError:
+        pass
+
+else:
+    raise ImportError('no os specific module found')
+
+sys.modules['os.path'] = path
+from os.path import (curdir, pardir, sep, pathsep, defpath, extsep, altsep,
+    devnull)
+
+del _names
+
+
+if _exists("_have_functions"):
+    _globals = globals()
+    def _add(str, fn):
+        if (fn in _globals) and (str in _have_functions):
+            _set.add(_globals[fn])
+
+    _set = set()
+    _add("HAVE_FACCESSAT",  "access")
+    _add("HAVE_FCHMODAT",   "chmod")
+    _add("HAVE_FCHOWNAT",   "chown")
+    _add("HAVE_FSTATAT",    "stat")
+    _add("HAVE_FUTIMESAT",  "utime")
+    _add("HAVE_LINKAT",     "link")
+    _add("HAVE_MKDIRAT",    "mkdir")
+    _add("HAVE_MKFIFOAT",   "mkfifo")
+    _add("HAVE_MKNODAT",    "mknod")
+    _add("HAVE_OPENAT",     "open")
+    _add("HAVE_READLINKAT", "readlink")
+    _add("HAVE_RENAMEAT",   "rename")
+    _add("HAVE_SYMLINKAT",  "symlink")
+    _add("HAVE_UNLINKAT",   "unlink")
+    _add("HAVE_UNLINKAT",   "rmdir")
+    _add("HAVE_UTIMENSAT",  "utime")
+    supports_dir_fd = _set
+
+    _set = set()
+    _add("HAVE_FACCESSAT",  "access")
+    supports_effective_ids = _set
+
+    _set = set()
+    _add("HAVE_FCHDIR",     "chdir")
+    _add("HAVE_FCHMOD",     "chmod")
+    _add("HAVE_FCHOWN",     "chown")
+    _add("HAVE_FDOPENDIR",  "listdir")
+    _add("HAVE_FDOPENDIR",  "scandir")
+    _add("HAVE_FEXECVE",    "execve")
+    _set.add(stat) # fstat always works
+    _add("HAVE_FTRUNCATE",  "truncate")
+    _add("HAVE_FUTIMENS",   "utime")
+    _add("HAVE_FUTIMES",    "utime")
+    _add("HAVE_FPATHCONF",  "pathconf")
+    if _exists("statvfs") and _exists("fstatvfs"): # mac os x10.3
+        _add("HAVE_FSTATVFS", "statvfs")
+    supports_fd = _set
+
+    _set = set()
+    _add("HAVE_FACCESSAT",  "access")
+    # Some platforms don't support lchmod().  Often the function exists
+    # anyway, as a stub that always returns ENOSUP or perhaps EOPNOTSUPP.
+    # (No, I don't know why that's a good design.)  ./configure will detect
+    # this and reject it--so HAVE_LCHMOD still won't be defined on such
+    # platforms.  This is Very Helpful.
+    #
+    # However, sometimes platforms without a working lchmod() *do* have
+    # fchmodat().  (Examples: Linux kernel 3.2 with glibc 2.15,
+    # OpenIndiana 3.x.)  And fchmodat() has a flag that theoretically makes
+    # it behave like lchmod().  So in theory it would be a suitable
+    # replacement for lchmod().  But when lchmod() doesn't work, fchmodat()'s
+    # flag doesn't work *either*.  Sadly ./configure isn't sophisticated
+    # enough to detect this condition--it only determines whether or not
+    # fchmodat() minimally works.
+    #
+    # Therefore we simply ignore fchmodat() when deciding whether or not
+    # os.chmod supports follow_symlinks.  Just checking lchmod() is
+    # sufficient.  After all--if you have a working fchmodat(), your
+    # lchmod() almost certainly works too.
+    #
+    # _add("HAVE_FCHMODAT",   "chmod")
+    _add("HAVE_FCHOWNAT",   "chown")
+    _add("HAVE_FSTATAT",    "stat")
+    _add("HAVE_LCHFLAGS",   "chflags")
+    _add("HAVE_LCHMOD",     "chmod")
+    if _exists("lchown"): # mac os x10.3
+        _add("HAVE_LCHOWN", "chown")
+    _add("HAVE_LINKAT",     "link")
+    _add("HAVE_LUTIMES",    "utime")
+    _add("HAVE_LSTAT",      "stat")
+    _add("HAVE_FSTATAT",    "stat")
+    _add("HAVE_UTIMENSAT",  "utime")
+    _add("MS_WINDOWS",      "stat")
+    supports_follow_symlinks = _set
+
+    del _set
+    del _have_functions
+    del _globals
+    del _add
+
+
+# Python uses fixed values for the SEEK_ constants; they are mapped
+# to native constants if necessary in posixmodule.c
+# Other possible SEEK values are directly imported from posixmodule.c
+SEEK_SET = 0
+SEEK_CUR = 1
+SEEK_END = 2
+
+# Super directory utilities.
+# (Inspired by Eric Raymond; the doc strings are mostly his)
+
+def makedirs(name, mode=0o777, exist_ok=False):
+    """makedirs(name [, mode=0o777][, exist_ok=False])
+
+    Super-mkdir; create a leaf directory and all intermediate ones.  Works like
+    mkdir, except that any intermediate path segment (not just the rightmost)
+    will be created if it does not exist. If the target directory already
+    exists, raise an OSError if exist_ok is False. Otherwise no exception is
+    raised.  This is recursive.
+
+    """
+    head, tail = path.split(name)
+    if not tail:
+        head, tail = path.split(head)
+    if head and tail and not path.exists(head):
+        try:
+            makedirs(head, exist_ok=exist_ok)
+        except FileExistsError:
+            # Defeats race condition when another thread created the path
+            pass
+        cdir = curdir
+        if isinstance(tail, bytes):
+            cdir = bytes(curdir, 'ASCII')
+        if tail == cdir:           # xxx/newdir/. exists if xxx/newdir exists
+            return
+    try:
+        mkdir(name, mode)
+    except OSError:
+        # Cannot rely on checking for EEXIST, since the operating system
+        # could give priority to other errors like EACCES or EROFS
+        if not exist_ok or not path.isdir(name):
+            raise
+
+def removedirs(name):
+    """removedirs(name)
+
+    Super-rmdir; remove a leaf directory and all empty intermediate
+    ones.  Works like rmdir except that, if the leaf directory is
+    successfully removed, directories corresponding to rightmost path
+    segments will be pruned away until either the whole path is
+    consumed or an error occurs.  Errors during this latter phase are
+    ignored -- they generally mean that a directory was not empty.
+
+    """
+    rmdir(name)
+    head, tail = path.split(name)
+    if not tail:
+        head, tail = path.split(head)
+    while head and tail:
+        try:
+            rmdir(head)
+        except OSError:
+            break
+        head, tail = path.split(head)
+
+def renames(old, new):
+    """renames(old, new)
+
+    Super-rename; create directories as necessary and delete any left
+    empty.  Works like rename, except creation of any intermediate
+    directories needed to make the new pathname good is attempted
+    first.  After the rename, directories corresponding to rightmost
+    path segments of the old name will be pruned until either the
+    whole path is consumed or a nonempty directory is found.
+
+    Note: this function can fail with the new directory structure made
+    if you lack permissions needed to unlink the leaf directory or
+    file.
+
+    """
+    head, tail = path.split(new)
+    if head and tail and not path.exists(head):
+        makedirs(head)
+    rename(old, new)
+    head, tail = path.split(old)
+    if head and tail:
+        try:
+            removedirs(head)
+        except OSError:
+            pass
+
+__all__.extend(["makedirs", "removedirs", "renames"])
+
+def walk(top, topdown=True, onerror=None, followlinks=False):
+    """Directory tree generator.
+
+    For each directory in the directory tree rooted at top (including top
+    itself, but excluding '.' and '..'), yields a 3-tuple
+
+        dirpath, dirnames, filenames
+
+    dirpath is a string, the path to the directory.  dirnames is a list of
+    the names of the subdirectories in dirpath (excluding '.' and '..').
+    filenames is a list of the names of the non-directory files in dirpath.
+    Note that the names in the lists are just names, with no path components.
+    To get a full path (which begins with top) to a file or directory in
+    dirpath, do os.path.join(dirpath, name).
+
+    If optional arg 'topdown' is true or not specified, the triple for a
+    directory is generated before the triples for any of its subdirectories
+    (directories are generated top down).  If topdown is false, the triple
+    for a directory is generated after the triples for all of its
+    subdirectories (directories are generated bottom up).
+
+    When topdown is true, the caller can modify the dirnames list in-place
+    (e.g., via del or slice assignment), and walk will only recurse into the
+    subdirectories whose names remain in dirnames; this can be used to prune the
+    search, or to impose a specific order of visiting.  Modifying dirnames when
+    topdown is false is ineffective, since the directories in dirnames have
+    already been generated by the time dirnames itself is generated. No matter
+    the value of topdown, the list of subdirectories is retrieved before the
+    tuples for the directory and its subdirectories are generated.
+
+    By default errors from the os.scandir() call are ignored.  If
+    optional arg 'onerror' is specified, it should be a function; it
+    will be called with one argument, an OSError instance.  It can
+    report the error to continue with the walk, or raise the exception
+    to abort the walk.  Note that the filename is available as the
+    filename attribute of the exception object.
+
+    By default, os.walk does not follow symbolic links to subdirectories on
+    systems that support them.  In order to get this functionality, set the
+    optional argument 'followlinks' to true.
+
+    Caution:  if you pass a relative pathname for top, don't change the
+    current working directory between resumptions of walk.  walk never
+    changes the current directory, and assumes that the client doesn't
+    either.
+
+    Example:
+
+    import os
+    from os.path import join, getsize
+    for root, dirs, files in os.walk('python/Lib/email'):
+        print(root, "consumes", end="")
+        print(sum([getsize(join(root, name)) for name in files]), end="")
+        print("bytes in", len(files), "non-directory files")
+        if 'CVS' in dirs:
+            dirs.remove('CVS')  # don't visit CVS directories
+
+    """
+    top = fspath(top)
+    dirs = []
+    nondirs = []
+    walk_dirs = []
+
+    # We may not have read permission for top, in which case we can't
+    # get a list of the files the directory contains.  os.walk
+    # always suppressed the exception then, rather than blow up for a
+    # minor reason when (say) a thousand readable directories are still
+    # left to visit.  That logic is copied here.
+    try:
+        # Note that scandir is global in this module due
+        # to earlier import-*.
+        scandir_it = scandir(top)
+    except OSError as error:
+        if onerror is not None:
+            onerror(error)
+        return
+
+    with scandir_it:
+        while True:
+            try:
+                try:
+                    entry = next(scandir_it)
+                except StopIteration:
+                    break
+            except OSError as error:
+                if onerror is not None:
+                    onerror(error)
+                return
+
+            try:
+                is_dir = entry.is_dir()
+            except OSError:
+                # If is_dir() raises an OSError, consider that the entry is not
+                # a directory, same behaviour than os.path.isdir().
+                is_dir = False
+
+            if is_dir:
+                dirs.append(entry.name)
+            else:
+                nondirs.append(entry.name)
+
+            if not topdown and is_dir:
+                # Bottom-up: recurse into sub-directory, but exclude symlinks to
+                # directories if followlinks is False
+                if followlinks:
+                    walk_into = True
+                else:
+                    try:
+                        is_symlink = entry.is_symlink()
+                    except OSError:
+                        # If is_symlink() raises an OSError, consider that the
+                        # entry is not a symbolic link, same behaviour than
+                        # os.path.islink().
+                        is_symlink = False
+                    walk_into = not is_symlink
+
+                if walk_into:
+                    walk_dirs.append(entry.path)
+
+    # Yield before recursion if going top down
+    if topdown:
+        yield top, dirs, nondirs
+
+        # Recurse into sub-directories
+        islink, join = path.islink, path.join
+        for dirname in dirs:
+            new_path = join(top, dirname)
+            # Issue #23605: os.path.islink() is used instead of caching
+            # entry.is_symlink() result during the loop on os.scandir() because
+            # the caller can replace the directory entry during the "yield"
+            # above.
+            if followlinks or not islink(new_path):
+                yield from walk(new_path, topdown, onerror, followlinks)
+    else:
+        # Recurse into sub-directories
+        for new_path in walk_dirs:
+            yield from walk(new_path, topdown, onerror, followlinks)
+        # Yield after recursion if going bottom up
+        yield top, dirs, nondirs
+
+__all__.append("walk")
+
+if {open, stat} <= supports_dir_fd and {scandir, stat} <= supports_fd:
+
+    def fwalk(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=None):
+        """Directory tree generator.
+
+        This behaves exactly like walk(), except that it yields a 4-tuple
+
+            dirpath, dirnames, filenames, dirfd
+
+        `dirpath`, `dirnames` and `filenames` are identical to walk() output,
+        and `dirfd` is a file descriptor referring to the directory `dirpath`.
+
+        The advantage of fwalk() over walk() is that it's safe against symlink
+        races (when follow_symlinks is False).
+
+        If dir_fd is not None, it should be a file descriptor open to a directory,
+          and top should be relative; top will then be relative to that directory.
+          (dir_fd is always supported for fwalk.)
+
+        Caution:
+        Since fwalk() yields file descriptors, those are only valid until the
+        next iteration step, so you should dup() them if you want to keep them
+        for a longer period.
+
+        Example:
+
+        import os
+        for root, dirs, files, rootfd in os.fwalk('python/Lib/email'):
+            print(root, "consumes", end="")
+            print(sum([os.stat(name, dir_fd=rootfd).st_size for name in files]),
+                  end="")
+            print("bytes in", len(files), "non-directory files")
+            if 'CVS' in dirs:
+                dirs.remove('CVS')  # don't visit CVS directories
+        """
+        if not isinstance(top, int) or not hasattr(top, '__index__'):
+            top = fspath(top)
+        # Note: To guard against symlink races, we use the standard
+        # lstat()/open()/fstat() trick.
+        if not follow_symlinks:
+            orig_st = stat(top, follow_symlinks=False, dir_fd=dir_fd)
+        topfd = open(top, O_RDONLY, dir_fd=dir_fd)
+        try:
+            if (follow_symlinks or (st.S_ISDIR(orig_st.st_mode) and
+                                    path.samestat(orig_st, stat(topfd)))):
+                yield from _fwalk(topfd, top, isinstance(top, bytes),
+                                  topdown, onerror, follow_symlinks)
+        finally:
+            close(topfd)
+
+    def _fwalk(topfd, toppath, isbytes, topdown, onerror, follow_symlinks):
+        # Note: This uses O(depth of the directory tree) file descriptors: if
+        # necessary, it can be adapted to only require O(1) FDs, see issue
+        # #13734.
+
+        scandir_it = scandir(topfd)
+        dirs = []
+        nondirs = []
+        entries = None if topdown or follow_symlinks else []
+        for entry in scandir_it:
+            name = entry.name
+            if isbytes:
+                name = fsencode(name)
+            try:
+                if entry.is_dir():
+                    dirs.append(name)
+                    if entries is not None:
+                        entries.append(entry)
+                else:
+                    nondirs.append(name)
+            except OSError:
+                try:
+                    # Add dangling symlinks, ignore disappeared files
+                    if entry.is_symlink():
+                        nondirs.append(name)
+                except OSError:
+                    pass
+
+        if topdown:
+            yield toppath, dirs, nondirs, topfd
+
+        for name in dirs if entries is None else zip(dirs, entries):
+            try:
+                if not follow_symlinks:
+                    if topdown:
+                        orig_st = stat(name, dir_fd=topfd, follow_symlinks=False)
+                    else:
+                        assert entries is not None
+                        name, entry = name
+                        orig_st = entry.stat(follow_symlinks=False)
+                dirfd = open(name, O_RDONLY, dir_fd=topfd)
+            except OSError as err:
+                if onerror is not None:
+                    onerror(err)
+                continue
+            try:
+                if follow_symlinks or path.samestat(orig_st, stat(dirfd)):
+                    dirpath = path.join(toppath, name)
+                    yield from _fwalk(dirfd, dirpath, isbytes,
+                                      topdown, onerror, follow_symlinks)
+            finally:
+                close(dirfd)
+
+        if not topdown:
+            yield toppath, dirs, nondirs, topfd
+
+    __all__.append("fwalk")
+
+# Make sure os.environ exists, at least
+try:
+    environ
+except NameError:
+    environ = {}
+
+def execl(file, *args):
+    """execl(file, *args)
+
+    Execute the executable file with argument list args, replacing the
+    current process. """
+    execv(file, args)
+
+def execle(file, *args):
+    """execle(file, *args, env)
+
+    Execute the executable file with argument list args and
+    environment env, replacing the current process. """
+    env = args[-1]
+    execve(file, args[:-1], env)
+
+def execlp(file, *args):
+    """execlp(file, *args)
+
+    Execute the executable file (which is searched for along $PATH)
+    with argument list args, replacing the current process. """
+    execvp(file, args)
+
+def execlpe(file, *args):
+    """execlpe(file, *args, env)
+
+    Execute the executable file (which is searched for along $PATH)
+    with argument list args and environment env, replacing the current
+    process. """
+    env = args[-1]
+    execvpe(file, args[:-1], env)
+
+def execvp(file, args):
+    """execvp(file, args)
+
+    Execute the executable file (which is searched for along $PATH)
+    with argument list args, replacing the current process.
+    args may be a list or tuple of strings. """
+    _execvpe(file, args)
+
+def execvpe(file, args, env):
+    """execvpe(file, args, env)
+
+    Execute the executable file (which is searched for along $PATH)
+    with argument list args and environment env , replacing the
+    current process.
+    args may be a list or tuple of strings. """
+    _execvpe(file, args, env)
+
+__all__.extend(["execl","execle","execlp","execlpe","execvp","execvpe"])
+
+def _execvpe(file, args, env=None):
+    if env is not None:
+        exec_func = execve
+        argrest = (args, env)
+    else:
+        exec_func = execv
+        argrest = (args,)
+        env = environ
+
+    if path.dirname(file):
+        exec_func(file, *argrest)
+        return
+    saved_exc = None
+    path_list = get_exec_path(env)
+    if name != 'nt':
+        file = fsencode(file)
+        path_list = map(fsencode, path_list)
+    for dir in path_list:
+        fullname = path.join(dir, file)
+        try:
+            exec_func(fullname, *argrest)
+        except (FileNotFoundError, NotADirectoryError) as e:
+            last_exc = e
+        except OSError as e:
+            last_exc = e
+            if saved_exc is None:
+                saved_exc = e
+    if saved_exc is not None:
+        raise saved_exc
+    raise last_exc
+
+
+def get_exec_path(env=None):
+    """Returns the sequence of directories that will be searched for the
+    named executable (similar to a shell) when launching a process.
+
+    *env* must be an environment variable dict or None.  If *env* is None,
+    os.environ will be used.
+    """
+    # Use a local import instead of a global import to limit the number of
+    # modules loaded at startup: the os module is always loaded at startup by
+    # Python. It may also avoid a bootstrap issue.
+    import warnings
+
+    if env is None:
+        env = environ
+
+    # {b'PATH': ...}.get('PATH') and {'PATH': ...}.get(b'PATH') emit a
+    # BytesWarning when using python -b or python -bb: ignore the warning
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", BytesWarning)
+
+        try:
+            path_list = env.get('PATH')
+        except TypeError:
+            path_list = None
+
+        if supports_bytes_environ:
+            try:
+                path_listb = env[b'PATH']
+            except (KeyError, TypeError):
+                pass
+            else:
+                if path_list is not None:
+                    raise ValueError(
+                        "env cannot contain 'PATH' and b'PATH' keys")
+                path_list = path_listb
+
+            if path_list is not None and isinstance(path_list, bytes):
+                path_list = fsdecode(path_list)
+
+    if path_list is None:
+        path_list = defpath
+    return path_list.split(pathsep)
+
+
+# Change environ to automatically call putenv(), unsetenv if they exist.
+from _collections_abc import MutableMapping
+
+class _Environ(MutableMapping):
+    def __init__(self, data, encodekey, decodekey, encodevalue, decodevalue, putenv, unsetenv):
+        self.encodekey = encodekey
+        self.decodekey = decodekey
+        self.encodevalue = encodevalue
+        self.decodevalue = decodevalue
+        self.putenv = putenv
+        self.unsetenv = unsetenv
+        self._data = data
+
+    def __getitem__(self, key):
+        try:
+            value = self._data[self.encodekey(key)]
+        except KeyError:
+            # raise KeyError with the original key value
+            raise KeyError(key) from None
+        return self.decodevalue(value)
+
+    def __setitem__(self, key, value):
+        key = self.encodekey(key)
+        value = self.encodevalue(value)
+        self.putenv(key, value)
+        self._data[key] = value
+
+    def __delitem__(self, key):
+        encodedkey = self.encodekey(key)
+        self.unsetenv(encodedkey)
+        try:
+            del self._data[encodedkey]
+        except KeyError:
+            # raise KeyError with the original key value
+            raise KeyError(key) from None
+
+    def __iter__(self):
+        # list() from dict object is an atomic operation
+        keys = list(self._data)
+        for key in keys:
+            yield self.decodekey(key)
+
+    def __len__(self):
+        return len(self._data)
+
+    def __repr__(self):
+        return 'environ({{{}}})'.format(', '.join(
+            ('{!r}: {!r}'.format(self.decodekey(key), self.decodevalue(value))
+            for key, value in self._data.items())))
+
+    def copy(self):
+        return dict(self)
+
+    def setdefault(self, key, value):
+        if key not in self:
+            self[key] = value
+        return self[key]
+
+try:
+    _putenv = putenv
+except NameError:
+    _putenv = lambda key, value: None
+else:
+    if "putenv" not in __all__:
+        __all__.append("putenv")
+
+try:
+    _unsetenv = unsetenv
+except NameError:
+    _unsetenv = lambda key: _putenv(key, "")
+else:
+    if "unsetenv" not in __all__:
+        __all__.append("unsetenv")
+
+def _createenviron():
+    if name == 'nt':
+        # Where Env Var Names Must Be UPPERCASE
+        def check_str(value):
+            if not isinstance(value, str):
+                raise TypeError("str expected, not %s" % type(value).__name__)
+            return value
+        encode = check_str
+        decode = str
+        def encodekey(key):
+            return encode(key).upper()
+        data = {}
+        for key, value in environ.items():
+            data[encodekey(key)] = value
+    else:
+        # Where Env Var Names Can Be Mixed Case
+        encoding = sys.getfilesystemencoding()
+        def encode(value):
+            if not isinstance(value, str):
+                raise TypeError("str expected, not %s" % type(value).__name__)
+            return value.encode(encoding, 'surrogateescape')
+        def decode(value):
+            return value.decode(encoding, 'surrogateescape')
+        encodekey = encode
+        data = environ
+    return _Environ(data,
+        encodekey, decode,
+        encode, decode,
+        _putenv, _unsetenv)
+
+# unicode environ
+environ = _createenviron()
+del _createenviron
+
+
+def getenv(key, default=None):
+    """Get an environment variable, return None if it doesn't exist.
+    The optional second argument can specify an alternate default.
+    key, default and the result are str."""
+    return environ.get(key, default)
+
+supports_bytes_environ = (name != 'nt')
+__all__.extend(("getenv", "supports_bytes_environ"))
+
+if supports_bytes_environ:
+    def _check_bytes(value):
+        if not isinstance(value, bytes):
+            raise TypeError("bytes expected, not %s" % type(value).__name__)
+        return value
+
+    # bytes environ
+    environb = _Environ(environ._data,
+        _check_bytes, bytes,
+        _check_bytes, bytes,
+        _putenv, _unsetenv)
+    del _check_bytes
+
+    def getenvb(key, default=None):
+        """Get an environment variable, return None if it doesn't exist.
+        The optional second argument can specify an alternate default.
+        key, default and the result are bytes."""
+        return environb.get(key, default)
+
+    __all__.extend(("environb", "getenvb"))
+
+def _fscodec():
+    encoding = sys.getfilesystemencoding()
+    errors = sys.getfilesystemencodeerrors()
+
+    def fsencode(filename):
+        """Encode filename (an os.PathLike, bytes, or str) to the filesystem
+        encoding with 'surrogateescape' error handler, return bytes unchanged.
+        On Windows, use 'strict' error handler if the file system encoding is
+        'mbcs' (which is the default encoding).
+        """
+        filename = fspath(filename)  # Does type-checking of `filename`.
+        if isinstance(filename, str):
+            return filename.encode(encoding, errors)
+        else:
+            return filename
+
+    def fsdecode(filename):
+        """Decode filename (an os.PathLike, bytes, or str) from the filesystem
+        encoding with 'surrogateescape' error handler, return str unchanged. On
+        Windows, use 'strict' error handler if the file system encoding is
+        'mbcs' (which is the default encoding).
+        """
+        filename = fspath(filename)  # Does type-checking of `filename`.
+        if isinstance(filename, bytes):
+            return filename.decode(encoding, errors)
+        else:
+            return filename
+
+    return fsencode, fsdecode
+
+fsencode, fsdecode = _fscodec()
+del _fscodec
+
+# Supply spawn*() (probably only for Unix)
+if _exists("fork") and not _exists("spawnv") and _exists("execv"):
+
+    P_WAIT = 0
+    P_NOWAIT = P_NOWAITO = 1
+
+    __all__.extend(["P_WAIT", "P_NOWAIT", "P_NOWAITO"])
+
+    # XXX Should we support P_DETACH?  I suppose it could fork()**2
+    # and close the std I/O streams.  Also, P_OVERLAY is the same
+    # as execv*()?
+
+    def _spawnvef(mode, file, args, env, func):
+        # Internal helper; func is the exec*() function to use
+        if not isinstance(args, (tuple, list)):
+            raise TypeError('argv must be a tuple or a list')
+        if not args or not args[0]:
+            raise ValueError('argv first element cannot be empty')
+        pid = fork()
+        if not pid:
+            # Child
+            try:
+                if env is None:
+                    func(file, args)
+                else:
+                    func(file, args, env)
+            except:
+                _exit(127)
+        else:
+            # Parent
+            if mode == P_NOWAIT:
+                return pid # Caller is responsible for waiting!
+            while 1:
+                wpid, sts = waitpid(pid, 0)
+                if WIFSTOPPED(sts):
+                    continue
+                elif WIFSIGNALED(sts):
+                    return -WTERMSIG(sts)
+                elif WIFEXITED(sts):
+                    return WEXITSTATUS(sts)
+                else:
+                    raise OSError("Not stopped, signaled or exited???")
+
+    def spawnv(mode, file, args):
+        """spawnv(mode, file, args) -> integer
+
+Execute file with arguments from args in a subprocess.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return _spawnvef(mode, file, args, None, execv)
+
+    def spawnve(mode, file, args, env):
+        """spawnve(mode, file, args, env) -> integer
+
+Execute file with arguments from args in a subprocess with the
+specified environment.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return _spawnvef(mode, file, args, env, execve)
+
+    # Note: spawnvp[e] isn't currently supported on Windows
+
+    def spawnvp(mode, file, args):
+        """spawnvp(mode, file, args) -> integer
+
+Execute file (which is looked for along $PATH) with arguments from
+args in a subprocess.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return _spawnvef(mode, file, args, None, execvp)
+
+    def spawnvpe(mode, file, args, env):
+        """spawnvpe(mode, file, args, env) -> integer
+
+Execute file (which is looked for along $PATH) with arguments from
+args in a subprocess with the supplied environment.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return _spawnvef(mode, file, args, env, execvpe)
+
+
+    __all__.extend(["spawnv", "spawnve", "spawnvp", "spawnvpe"])
+
+
+if _exists("spawnv"):
+    # These aren't supplied by the basic Windows code
+    # but can be easily implemented in Python
+
+    def spawnl(mode, file, *args):
+        """spawnl(mode, file, *args) -> integer
+
+Execute file with arguments from args in a subprocess.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return spawnv(mode, file, args)
+
+    def spawnle(mode, file, *args):
+        """spawnle(mode, file, *args, env) -> integer
+
+Execute file with arguments from args in a subprocess with the
+supplied environment.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        env = args[-1]
+        return spawnve(mode, file, args[:-1], env)
+
+
+    __all__.extend(["spawnl", "spawnle"])
+
+
+if _exists("spawnvp"):
+    # At the moment, Windows doesn't implement spawnvp[e],
+    # so it won't have spawnlp[e] either.
+    def spawnlp(mode, file, *args):
+        """spawnlp(mode, file, *args) -> integer
+
+Execute file (which is looked for along $PATH) with arguments from
+args in a subprocess with the supplied environment.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        return spawnvp(mode, file, args)
+
+    def spawnlpe(mode, file, *args):
+        """spawnlpe(mode, file, *args, env) -> integer
+
+Execute file (which is looked for along $PATH) with arguments from
+args in a subprocess with the supplied environment.
+If mode == P_NOWAIT return the pid of the process.
+If mode == P_WAIT return the process's exit code if it exits normally;
+otherwise return -SIG, where SIG is the signal that killed it. """
+        env = args[-1]
+        return spawnvpe(mode, file, args[:-1], env)
+
+
+    __all__.extend(["spawnlp", "spawnlpe"])
+
+
+# Supply os.popen()
+def popen(cmd, mode="r", buffering=-1):
+    if not isinstance(cmd, str):
+        raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))
+    if mode not in ("r", "w"):
+        raise ValueError("invalid mode %r" % mode)
+    if buffering == 0 or buffering is None:
+        raise ValueError("popen() does not support unbuffered streams")
+    import subprocess, io
+    if mode == "r":
+        proc = subprocess.Popen(cmd,
+                                shell=True,
+                                stdout=subprocess.PIPE,
+                                bufsize=buffering)
+        return _wrap_close(io.TextIOWrapper(proc.stdout), proc)
+    else:
+        proc = subprocess.Popen(cmd,
+                                shell=True,
+                                stdin=subprocess.PIPE,
+                                bufsize=buffering)
+        return _wrap_close(io.TextIOWrapper(proc.stdin), proc)
+
+# Helper for popen() -- a proxy for a file whose close waits for the process
+class _wrap_close:
+    def __init__(self, stream, proc):
+        self._stream = stream
+        self._proc = proc
+    def close(self):
+        self._stream.close()
+        returncode = self._proc.wait()
+        if returncode == 0:
+            return None
+        if name == 'nt':
+            return returncode
+        else:
+            return returncode << 8  # Shift left to match old behavior
+    def __enter__(self):
+        return self
+    def __exit__(self, *args):
+        self.close()
+    def __getattr__(self, name):
+        return getattr(self._stream, name)
+    def __iter__(self):
+        return iter(self._stream)
+
+# Supply os.fdopen()
+def fdopen(fd, *args, **kwargs):
+    if not isinstance(fd, int):
+        raise TypeError("invalid fd type (%s, expected integer)" % type(fd))
+    import io
+    return io.open(fd, *args, **kwargs)
+
+
+# For testing purposes, make sure the function is available when the C
+# implementation exists.
+def _fspath(path):
+    """Return the path representation of a path-like object.
+
+    If str or bytes is passed in, it is returned unchanged. Otherwise the
+    os.PathLike interface is used to get the path representation. If the
+    path representation is not str or bytes, TypeError is raised. If the
+    provided path is not str, bytes, or os.PathLike, TypeError is raised.
+    """
+    if isinstance(path, (str, bytes)):
+        return path
+
+    # Work from the object's type to match method resolution of other magic
+    # methods.
+    path_type = type(path)
+    try:
+        path_repr = path_type.__fspath__(path)
+    except AttributeError:
+        if hasattr(path_type, '__fspath__'):
+            raise
+        else:
+            raise TypeError("expected str, bytes or os.PathLike object, "
+                            "not " + path_type.__name__)
+    if isinstance(path_repr, (str, bytes)):
+        return path_repr
+    else:
+        raise TypeError("expected {}.__fspath__() to return str or bytes, "
+                        "not {}".format(path_type.__name__,
+                                        type(path_repr).__name__))
+
+# If there is no C implementation, make the pure Python version the
+# implementation as transparently as possible.
+if not _exists('fspath'):
+    fspath = _fspath
+    fspath.__name__ = "fspath"
+
+
+class PathLike(abc.ABC):
+
+    """Abstract base class for implementing the file system path protocol."""
+
+    @abc.abstractmethod
+    def __fspath__(self):
+        """Return the file system path representation of the object."""
+        raise NotImplementedError
+
+    @classmethod
+    def __subclasshook__(cls, subclass):
+        return hasattr(subclass, '__fspath__')