"""Object-oriented filesystem paths.

This module provides classes to represent abstract paths and concrete
paths with operations that have semantics appropriate for different
operating systems.
"""

import io
import ntpath
import operator
import os
import posixpath
import sys
from errno import *
from itertools import chain
from stat import (
    S_IMODE, S_ISDIR, S_ISREG, S_ISLNK, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO,
)
from _collections_abc import Sequence
lazy import shutil
lazy from glob import _StringGlobber, _no_recurse_symlinks

try:
    import pwd
except ImportError:
    pwd = None
try:
    import grp
except ImportError:
    grp = None

from pathlib._os import (
    vfsopen, vfspath,
    ensure_different_files, ensure_distinct_paths,
    copyfile2, copyfileobj,
)


__all__ = [
    "UnsupportedOperation",
    "PurePath", "PurePosixPath", "PureWindowsPath",
    "Path", "PosixPath", "WindowsPath",
    ]


class UnsupportedOperation(NotImplementedError):
    """An exception that is raised when an unsupported operation is attempted.
    """
    pass


class _PathParents(Sequence):
    """This object provides sequence-like access to the logical ancestors
    of a path.  Don't try to construct it yourself."""
    __slots__ = ('_path', '_drv', '_root', '_tail')

    def __init__(self, path):
        self._path = path
        self._drv = path.drive
        self._root = path.root
        self._tail = path._tail

    def __len__(self):
        return len(self._tail)

    def __getitem__(self, idx):
        if isinstance(idx, slice):
            return tuple(self[i] for i in range(*idx.indices(len(self))))

        if idx >= len(self) or idx < -len(self):
            raise IndexError(idx)
        if idx < 0:
            idx += len(self)
        return self._path._from_parsed_parts(self._drv, self._root,
                                             self._tail[:-idx - 1])

    def __repr__(self):
        return "<{}.parents>".format(type(self._path).__name__)


class PurePath:
    """Base class for manipulating paths without I/O.

    PurePath represents a filesystem path and offers operations which
    don't imply any actual filesystem I/O.  Depending on your system,
    instantiating a PurePath will return either a PurePosixPath or a
    PureWindowsPath object.  You can also instantiate either of these classes
    directly, regardless of your system.
    """

    __slots__ = (
        # The `_raw_paths` slot stores unjoined string paths. This is set in
        # the `__init__()` method.
        '_raw_paths',

        # The `_drv`, `_root` and `_tail_cached` slots store parsed and
        # normalized parts of the path. They are set when any of the `drive`,
        # `root` or `_tail` properties are accessed for the first time. The
        # three-part division corresponds to the result of
        # `os.path.splitroot()`, except that the tail is further split on path
        # separators (i.e. it is a list of strings), and that the root and
        # tail are normalized.
        '_drv', '_root', '_tail_cached',

        # The `_str` slot stores the string representation of the path,
        # computed from the drive, root and tail when `__str__()` is called
        # for the first time. It's used to implement `_str_normcase`
        '_str',

        # The `_str_normcase_cached` slot stores the string path with
        # normalized case. It is set when the `_str_normcase` property is
        # accessed for the first time. It's used to implement `__eq__()`
        # `__hash__()`, and `_parts_normcase`
        '_str_normcase_cached',

        # The `_parts_normcase_cached` slot stores the case-normalized
        # string path after splitting on path separators. It's set when the
        # `_parts_normcase` property is accessed for the first time. It's used
        # to implement comparison methods like `__lt__()`.
        '_parts_normcase_cached',

        # The `_hash` slot stores the hash of the case-normalized string
        # path. It's set when `__hash__()` is called for the first time.
        '_hash',
    )
    parser = os.path

    def __new__(cls, *args, **kwargs):
        """Construct a PurePath from one or several strings and or existing
        PurePath objects.  The strings and path objects are combined so as
        to yield a canonicalized path, which is incorporated into the
        new PurePath object.
        """
        if cls is PurePath:
            cls = PureWindowsPath if os.name == 'nt' else PurePosixPath
        return object.__new__(cls)

    def __init__(self, *args):
        paths = []
        for arg in args:
            if isinstance(arg, PurePath):
                if arg.parser is not self.parser:
                    # GH-103631: Convert separators for backwards compatibility.
                    paths.append(arg.as_posix())
                else:
                    paths.extend(arg._raw_paths)
            else:
                try:
                    path = os.fspath(arg)
                except TypeError:
                    path = arg
                if not isinstance(path, str):
                    raise TypeError(
                        "argument should be a str or an os.PathLike "
                        "object where __fspath__ returns a str, "
                        f"not {type(path).__name__!r}")
                paths.append(path)
        self._raw_paths = paths

    def with_segments(self, *pathsegments):
        """Construct a new path object from any number of path-like objects.
        Subclasses may override this method to customize how new path objects
        are created from methods like `iterdir()`.
        """
        return type(self)(*pathsegments)

    def joinpath(self, *pathsegments):
        """Combine this path with one or several arguments, and return a
        new path representing either a subpath (if all arguments are relative
        paths) or a totally different path (if one of the arguments is
        anchored).
        """
        return self.with_segments(self, *pathsegments)

    def __truediv__(self, key):
        try:
            return self.with_segments(self, key)
        except TypeError:
            return NotImplemented

    def __rtruediv__(self, key):
        try:
            return self.with_segments(key, self)
        except TypeError:
            return NotImplemented

    def __reduce__(self):
        return self.__class__, tuple(self._raw_paths)

    def __repr__(self):
        return "{}({!r})".format(self.__class__.__name__, self.as_posix())

    def __bytes__(self):
        """Return the bytes representation of the path.  This is only
        recommended to use under Unix."""
        return os.fsencode(self)

    @property
    def _str_normcase(self):
        # String with normalized case, for hashing and equality checks
        try:
            return self._str_normcase_cached
        except AttributeError:
            if self.parser is posixpath:
                self._str_normcase_cached = str(self)
            else:
                self._str_normcase_cached = str(self).lower()
            return self._str_normcase_cached

    def __hash__(self):
        try:
            return self._hash
        except AttributeError:
            self._hash = hash(self._str_normcase)
            return self._hash

    def __eq__(self, other):
        if not isinstance(other, PurePath):
            return NotImplemented
        return self._str_normcase == other._str_normcase and self.parser is other.parser

    @property
    def _parts_normcase(self):
        # Cached parts with normalized case, for comparisons.
        try:
            return self._parts_normcase_cached
        except AttributeError:
            self._parts_normcase_cached = self._str_normcase.split(self.parser.sep)
            return self._parts_normcase_cached

    def __lt__(self, other):
        if not isinstance(other, PurePath) or self.parser is not other.parser:
            return NotImplemented
        return self._parts_normcase < other._parts_normcase

    def __le__(self, other):
        if not isinstance(other, PurePath) or self.parser is not other.parser:
            return NotImplemented
        return self._parts_normcase <= other._parts_normcase

    def __gt__(self, other):
        if not isinstance(other, PurePath) or self.parser is not other.parser:
            return NotImplemented
        return self._parts_normcase > other._parts_normcase

    def __ge__(self, other):
        if not isinstance(other, PurePath) or self.parser is not other.parser:
            return NotImplemented
        return self._parts_normcase >= other._parts_normcase

    def __str__(self):
        """Return the string representation of the path, suitable for
        passing to system calls."""
        try:
            return self._str
        except AttributeError:
            self._str = self._format_parsed_parts(self.drive, self.root,
                                                  self._tail) or '.'
            return self._str

    __fspath__ = __str__
    __vfspath__ = __str__

    @classmethod
    def _format_parsed_parts(cls, drv, root, tail):
        if drv or root:
            return drv + root + cls.parser.sep.join(tail)
        elif tail and cls.parser.splitdrive(tail[0])[0]:
            tail = ['.'] + tail
        return cls.parser.sep.join(tail)

    def _from_parsed_parts(self, drv, root, tail):
        path = self._from_parsed_string(self._format_parsed_parts(drv, root, tail))
        path._drv = drv
        path._root = root
        path._tail_cached = tail
        return path

    def _from_parsed_string(self, path_str):
        path = self.with_segments(path_str)
        path._str = path_str or '.'
        return path

    @classmethod
    def _parse_path(cls, path):
        if not path:
            return '', '', []
        sep = cls.parser.sep
        altsep = cls.parser.altsep
        if altsep:
            path = path.replace(altsep, sep)
        drv, root, rel = cls.parser.splitroot(path)
        if not root and drv.startswith(sep) and not drv.endswith(sep):
            drv_parts = drv.split(sep)
            if len(drv_parts) == 4 and drv_parts[2] not in '?.':
                # e.g. //server/share
                root = sep
            elif len(drv_parts) == 6:
                # e.g. //?/unc/server/share
                root = sep
        return drv, root, [x for x in rel.split(sep) if x and x != '.']

    @classmethod
    def _parse_pattern(cls, pattern):
        """Parse a glob pattern to a list of parts. This is much like
        _parse_path, except:

        - Rather than normalizing and returning the drive and root, we raise
          NotImplementedError if either are present.
        - If the path has no real parts, we raise ValueError.
        - If the path ends in a slash, then a final empty part is added.
        """
        drv, root, rel = cls.parser.splitroot(pattern)
        if root or drv:
            raise NotImplementedError("Non-relative patterns are unsupported")
        sep = cls.parser.sep
        altsep = cls.parser.altsep
        if altsep:
            rel = rel.replace(altsep, sep)
        parts = [x for x in rel.split(sep) if x and x != '.']
        if not parts:
            raise ValueError(f"Unacceptable pattern: {str(pattern)!r}")
        elif rel.endswith(sep):
            # GH-65238: preserve trailing slash in glob patterns.
            parts.append('')
        return parts

    def as_posix(self):
        """Return the string representation of the path with forward (/)
        slashes."""
        return str(self).replace(self.parser.sep, '/')

    @property
    def _raw_path(self):
        paths = self._raw_paths
        if len(paths) == 1:
            return paths[0]
        elif paths:
            # Join path segments from the initializer.
            return self.parser.join(*paths)
        else:
            return ''

    @property
    def drive(self):
        """The drive prefix (letter or UNC path), if any."""
        try:
            return self._drv
        except AttributeError:
            self._drv, self._root, self._tail_cached = self._parse_path(self._raw_path)
            return self._drv

    @property
    def root(self):
        """The root of the path, if any."""
        try:
            return self._root
        except AttributeError:
            self._drv, self._root, self._tail_cached = self._parse_path(self._raw_path)
            return self._root

    @property
    def _tail(self):
        try:
            return self._tail_cached
        except AttributeError:
            self._drv, self._root, self._tail_cached = self._parse_path(self._raw_path)
            return self._tail_cached

    @property
    def anchor(self):
        """The concatenation of the drive and root, or ''."""
        return self.drive + self.root

    @property
    def parts(self):
        """An object providing sequence-like access to the
        components in the filesystem path."""
        if self.drive or self.root:
            return (self.drive + self.root,) + tuple(self._tail)
        else:
            return tuple(self._tail)

    @property
    def parent(self):
        """The logical parent of the path."""
        drv = self.drive
        root = self.root
        tail = self._tail
        if not tail:
            return self
        return self._from_parsed_parts(drv, root, tail[:-1])

    @property
    def parents(self):
        """A sequence of this path's logical parents."""
        # The value of this property should not be cached on the path object,
        # as doing so would introduce a reference cycle.
        return _PathParents(self)

    @property
    def name(self):
        """The final path component, if any."""
        tail = self._tail
        if not tail:
            return ''
        return tail[-1]

    def with_name(self, name):
        """Return a new path with the file name changed."""
        p = self.parser
        if not name or p.sep in name or (p.altsep and p.altsep in name) or name == '.':
            raise ValueError(f"Invalid name {name!r}")
        tail = self._tail.copy()
        if not tail:
            raise ValueError(f"{self!r} has an empty name")
        tail[-1] = name
        return self._from_parsed_parts(self.drive, self.root, tail)

    def with_stem(self, stem):
        """Return a new path with the stem changed."""
        suffix = self.suffix
        if not suffix:
            return self.with_name(stem)
        elif not stem:
            # If the suffix is non-empty, we can't make the stem empty.
            raise ValueError(f"{self!r} has a non-empty suffix")
        else:
            return self.with_name(stem + suffix)

    def with_suffix(self, suffix):
        """Return a new path with the file suffix changed.  If the path
        has no suffix, add given suffix.  If the given suffix is an empty
        string, remove the suffix from the path.
        """
        stem = self.stem
        if not stem:
            # If the stem is empty, we can't make the suffix non-empty.
            raise ValueError(f"{self!r} has an empty name")
        elif suffix and not suffix.startswith('.'):
            raise ValueError(f"Invalid suffix {suffix!r}")
        else:
            return self.with_name(stem + suffix)

    @property
    def stem(self):
        """The final path component, minus its last suffix."""
        name = self.name
        i = name.rfind('.')
        if i != -1:
            stem = name[:i]
            # Stem must contain at least one non-dot character.
            if stem.lstrip('.'):
                return stem
        return name

    @property
    def suffix(self):
        """
        The final component's last suffix, if any.

        This includes the leading period. For example: '.txt'
        """
        name = self.name.lstrip('.')
        i = name.rfind('.')
        if i != -1:
            return name[i:]
        return ''

    @property
    def suffixes(self):
        """
        A list of the final component's suffixes, if any.

        These include the leading periods. For example: ['.tar', '.gz']
        """
        return ['.' + ext for ext in self.name.lstrip('.').split('.')[1:]]

    def relative_to(self, other, *, walk_up=False):
        """Return the relative path to another path identified by the passed
        arguments.  If the operation is not possible (because this is not
        related to the other path), raise ValueError.

        The *walk_up* parameter controls whether `..` may be used to resolve
        the path.
        """
        if not hasattr(other, 'with_segments'):
            other = self.with_segments(other)
        parts = []
        for path in chain([other], other.parents):
            if path == self or path in self.parents:
                break
            elif not walk_up:
                raise ValueError(f"{str(self)!r} is not in the subpath of {str(other)!r}")
            elif path.name == '..':
                raise ValueError(f"'..' segment in {str(other)!r} cannot be walked")
            else:
                parts.append('..')
        else:
            raise ValueError(f"{str(self)!r} and {str(other)!r} have different anchors")
        parts.extend(self._tail[len(path._tail):])
        return self._from_parsed_parts('', '', parts)

    def is_relative_to(self, other):
        """Return True if the path is relative to another path or False.
        """
        if not hasattr(other, 'with_segments'):
            other = self.with_segments(other)
        return other == self or other in self.parents

    def is_absolute(self):
        """True if the path is absolute (has both a root and, if applicable,
        a drive)."""
        if self.parser is posixpath:
            # Optimization: work with raw paths on POSIX.
            for path in self._raw_paths:
                if path.startswith('/'):
                    return True
            return False
        return self.parser.isabs(self)

    def as_uri(self):
        """Return the path as a URI."""
        import warnings
        msg = ("pathlib.PurePath.as_uri() is deprecated and scheduled "
               "for removal in Python 3.19. Use pathlib.Path.as_uri().")
        warnings._deprecated("pathlib.PurePath.as_uri", msg, remove=(3, 19))
        if not self.is_absolute():
            raise ValueError("relative path can't be expressed as a file URI")

        drive = self.drive
        if len(drive) == 2 and drive[1] == ':':
            # It's a path on a local drive => 'file:///c:/a/b'
            prefix = 'file:///' + drive
            path = self.as_posix()[2:]
        elif drive:
            # It's a path on a network drive => 'file://host/share/a/b'
            prefix = 'file:'
            path = self.as_posix()
        else:
            # It's a posix path => 'file:///etc/hosts'
            prefix = 'file://'
            path = str(self)
        from urllib.parse import quote_from_bytes
        return prefix + quote_from_bytes(os.fsencode(path))

    def full_match(self, pattern, *, case_sensitive=None):
        """
        Return True if this path matches the given glob-style pattern. The
        pattern is matched against the entire path.
        """
        if not hasattr(pattern, 'with_segments'):
            pattern = self.with_segments(pattern)
        if case_sensitive is None:
            case_sensitive = self.parser is posixpath

        # The string representation of an empty path is a single dot ('.'). Empty
        # paths shouldn't match wildcards, so we change it to the empty string.
        path = str(self) if self.parts else ''
        pattern = str(pattern) if pattern.parts else ''
        globber = _StringGlobber(self.parser.sep, case_sensitive, recursive=True)
        return globber.compile(pattern)(path) is not None

    def match(self, path_pattern, *, case_sensitive=None):
        """
        Return True if this path matches the given pattern. If the pattern is
        relative, matching is done from the right; otherwise, the entire path
        is matched. The recursive wildcard '**' is *not* supported by this
        method.
        """
        if not hasattr(path_pattern, 'with_segments'):
            path_pattern = self.with_segments(path_pattern)
        if case_sensitive is None:
            case_sensitive = self.parser is posixpath
        path_parts = self.parts[::-1]
        pattern_parts = path_pattern.parts[::-1]
        if not pattern_parts:
            raise ValueError("empty pattern")
        if len(path_parts) < len(pattern_parts):
            return False
        if len(path_parts) > len(pattern_parts) and path_pattern.anchor:
            return False
        globber = _StringGlobber(self.parser.sep, case_sensitive)
        for path_part, pattern_part in zip(path_parts, pattern_parts):
            match = globber.compile(pattern_part)
            if match(path_part) is None:
                return False
        return True

# Subclassing os.PathLike makes isinstance() checks slower,
# which in turn makes Path construction slower. Register instead!
os.PathLike.register(PurePath)


class PurePosixPath(PurePath):
    """PurePath subclass for non-Windows systems.

    On a POSIX system, instantiating a PurePath should return this object.
    However, you can also instantiate it directly on any system.
    """
    parser = posixpath
    __slots__ = ()


class PureWindowsPath(PurePath):
    """PurePath subclass for Windows systems.

    On a Windows system, instantiating a PurePath should return this object.
    However, you can also instantiate it directly on any system.
    """
    parser = ntpath
    __slots__ = ()


_STAT_RESULT_ERROR = []  # falsy sentinel indicating stat() failed.


class _Info:
    """Implementation of pathlib.types.PathInfo that provides status
    information by querying a wrapped os.stat_result object. Don't try to
    construct it yourself."""
    __slots__ = ('_path', '_entry', '_stat_result', '_lstat_result')

    def __init__(self, path, entry=None):
        self._path = path
        self._entry = entry
        self._stat_result = None
        self._lstat_result = None

    def __repr__(self):
        path_type = "WindowsPath" if os.name == "nt" else "PosixPath"
        return f"<{path_type}.info>"

    def _stat(self, *, follow_symlinks=True):
        """Return the status as an os.stat_result."""
        if self._entry:
            return self._entry.stat(follow_symlinks=follow_symlinks)
        if follow_symlinks:
            if not self._stat_result:
                try:
                    self._stat_result = os.stat(self._path)
                except (OSError, ValueError):
                    self._stat_result = _STAT_RESULT_ERROR
                    raise
            return self._stat_result
        else:
            if not self._lstat_result:
                try:
                    self._lstat_result = os.lstat(self._path)
                except (OSError, ValueError):
                    self._lstat_result = _STAT_RESULT_ERROR
                    raise
            return self._lstat_result

    def exists(self, *, follow_symlinks=True):
        """Whether this path exists."""
        if self._entry:
            if not follow_symlinks:
                return True
        if follow_symlinks:
            if self._stat_result is _STAT_RESULT_ERROR:
                return False
        else:
            if self._lstat_result is _STAT_RESULT_ERROR:
                return False
        try:
            self._stat(follow_symlinks=follow_symlinks)
        except (OSError, ValueError):
            return False
        return True

    def is_dir(self, *, follow_symlinks=True):
        """Whether this path is a directory."""
        if self._entry:
            try:
                return self._entry.is_dir(follow_symlinks=follow_symlinks)
            except OSError:
                return False
        if follow_symlinks:
            if self._stat_result is _STAT_RESULT_ERROR:
                return False
        else:
            if self._lstat_result is _STAT_RESULT_ERROR:
                return False
        try:
            st = self._stat(follow_symlinks=follow_symlinks)
        except (OSError, ValueError):
            return False
        return S_ISDIR(st.st_mode)

    def is_file(self, *, follow_symlinks=True):
        """Whether this path is a regular file."""
        if self._entry:
            try:
                return self._entry.is_file(follow_symlinks=follow_symlinks)
            except OSError:
                return False
        if follow_symlinks:
            if self._stat_result is _STAT_RESULT_ERROR:
                return False
        else:
            if self._lstat_result is _STAT_RESULT_ERROR:
                return False
        try:
            st = self._stat(follow_symlinks=follow_symlinks)
        except (OSError, ValueError):
            return False
        return S_ISREG(st.st_mode)

    def is_symlink(self):
        """Whether this path is a symbolic link."""
        if self._entry:
            try:
                return self._entry.is_symlink()
            except OSError:
                return False
        if self._lstat_result is _STAT_RESULT_ERROR:
            return False
        try:
            st = self._stat(follow_symlinks=False)
        except (OSError, ValueError):
            return False
        return S_ISLNK(st.st_mode)

    def _posix_permissions(self, *, follow_symlinks=True):
        """Return the POSIX file permissions."""
        return S_IMODE(self._stat(follow_symlinks=follow_symlinks).st_mode)

    def _file_id(self, *, follow_symlinks=True):
        """Returns the identifier of the file."""
        st = self._stat(follow_symlinks=follow_symlinks)
        return st.st_dev, st.st_ino

    def _access_time_ns(self, *, follow_symlinks=True):
        """Return the access time in nanoseconds."""
        return self._stat(follow_symlinks=follow_symlinks).st_atime_ns

    def _mod_time_ns(self, *, follow_symlinks=True):
        """Return the modify time in nanoseconds."""
        return self._stat(follow_symlinks=follow_symlinks).st_mtime_ns

    if hasattr(os.stat_result, 'st_flags'):
        def _bsd_flags(self, *, follow_symlinks=True):
            """Return the flags."""
            return self._stat(follow_symlinks=follow_symlinks).st_flags

    if hasattr(os, 'listxattr'):
        def _xattrs(self, *, follow_symlinks=True):
            """Return the xattrs as a list of (attr, value) pairs, or an empty
            list if extended attributes aren't supported."""
            try:
                return [
                    (attr, os.getxattr(self._path, attr, follow_symlinks=follow_symlinks))
                    for attr in os.listxattr(self._path, follow_symlinks=follow_symlinks)]
            except OSError as err:
                if err.errno not in (EPERM, ENOTSUP, ENODATA, EINVAL, EACCES):
                    raise
                return []


def _copy_info(info, target, follow_symlinks=True):
    """Copy metadata from the given PathInfo to the given local path."""
    copy_times_ns = (
        hasattr(info, '_access_time_ns') and
        hasattr(info, '_mod_time_ns') and
        (follow_symlinks or os.utime in os.supports_follow_symlinks))
    if copy_times_ns:
        t0 = info._access_time_ns(follow_symlinks=follow_symlinks)
        t1 = info._mod_time_ns(follow_symlinks=follow_symlinks)
        os.utime(target, ns=(t0, t1), follow_symlinks=follow_symlinks)

    # We must copy extended attributes before the file is (potentially)
    # chmod()'ed read-only, otherwise setxattr() will error with -EACCES.
    copy_xattrs = (
        hasattr(info, '_xattrs') and
        hasattr(os, 'setxattr') and
        (follow_symlinks or os.setxattr in os.supports_follow_symlinks))
    if copy_xattrs:
        xattrs = info._xattrs(follow_symlinks=follow_symlinks)
        for attr, value in xattrs:
            try:
                os.setxattr(target, attr, value, follow_symlinks=follow_symlinks)
            except OSError as e:
                if e.errno not in (EPERM, ENOTSUP, ENODATA, EINVAL, EACCES):
                    raise

    copy_posix_permissions = (
        hasattr(info, '_posix_permissions') and
        (follow_symlinks or os.chmod in os.supports_follow_symlinks))
    if copy_posix_permissions:
        posix_permissions = info._posix_permissions(follow_symlinks=follow_symlinks)
        try:
            os.chmod(target, posix_permissions, follow_symlinks=follow_symlinks)
        except NotImplementedError:
            # if we got a NotImplementedError, it's because
            #   * follow_symlinks=False,
            #   * lchown() is unavailable, and
            #   * either
            #       * fchownat() is unavailable or
            #       * fchownat() doesn't implement AT_SYMLINK_NOFOLLOW.
            #         (it returned ENOSUP.)
            # therefore we're out of options--we simply cannot chown the
            # symlink.  give up, suppress the error.
            # (which is what shutil always did in this circumstance.)
            pass

    copy_bsd_flags = (
        hasattr(info, '_bsd_flags') and
        hasattr(os, 'chflags') and
        (follow_symlinks or os.chflags in os.supports_follow_symlinks))
    if copy_bsd_flags:
        bsd_flags = info._bsd_flags(follow_symlinks=follow_symlinks)
        try:
            os.chflags(target, bsd_flags, follow_symlinks=follow_symlinks)
        except OSError as why:
            if why.errno not in (EOPNOTSUPP, ENOTSUP):
                raise


class Path(PurePath):
    """PurePath subclass that can make system calls.

    Path represents a filesystem path but unlike PurePath, also offers
    methods to do system calls on path objects. Depending on your system,
    instantiating a Path will return either a PosixPath or a WindowsPath
    object. You can also instantiate a PosixPath or WindowsPath directly,
    but cannot instantiate a WindowsPath on a POSIX system or vice versa.
    """
    __slots__ = ('_info',)

    def __new__(cls, *args, **kwargs):
        if cls is Path:
            cls = WindowsPath if os.name == 'nt' else PosixPath
        return object.__new__(cls)

    @property
    def info(self):
        """
        A PathInfo object that exposes the file type and other file attributes
        of this path.
        """
        try:
            return self._info
        except AttributeError:
            self._info = _Info(str(self))
            return self._info

    def stat(self, *, follow_symlinks=True):
        """
        Return the result of the stat() system call on this path, like
        os.stat() does.
        """
        return os.stat(self, follow_symlinks=follow_symlinks)

    def lstat(self):
        """
        Like stat(), except if the path points to a symlink, the symlink's
        status information is returned, rather than its target's.
        """
        return os.lstat(self)

    def exists(self, *, follow_symlinks=True):
        """
        Whether this path exists.

        This method normally follows symlinks; to check whether a symlink exists,
        add the argument follow_symlinks=False.
        """
        if follow_symlinks:
            return os.path.exists(self)
        return os.path.lexists(self)

    def is_dir(self, *, follow_symlinks=True):
        """
        Whether this path is a directory.
        """
        if follow_symlinks:
            return os.path.isdir(self)
        try:
            return S_ISDIR(self.stat(follow_symlinks=follow_symlinks).st_mode)
        except (OSError, ValueError):
            return False

    def is_file(self, *, follow_symlinks=True):
        """
        Whether this path is a regular file (also True for symlinks pointing
        to regular files).
        """
        if follow_symlinks:
            return os.path.isfile(self)
        try:
            return S_ISREG(self.stat(follow_symlinks=follow_symlinks).st_mode)
        except (OSError, ValueError):
            return False

    def is_mount(self):
        """
        Check if this path is a mount point
        """
        return os.path.ismount(self)

    def is_symlink(self):
        """
        Whether this path is a symbolic link.
        """
        return os.path.islink(self)

    def is_junction(self):
        """
        Whether this path is a junction.
        """
        return os.path.isjunction(self)

    def is_block_device(self):
        """
        Whether this path is a block device.
        """
        try:
            return S_ISBLK(self.stat().st_mode)
        except (OSError, ValueError):
            return False

    def is_char_device(self):
        """
        Whether this path is a character device.
        """
        try:
            return S_ISCHR(self.stat().st_mode)
        except (OSError, ValueError):
            return False

    def is_fifo(self):
        """
        Whether this path is a FIFO.
        """
        try:
            return S_ISFIFO(self.stat().st_mode)
        except (OSError, ValueError):
            return False

    def is_socket(self):
        """
        Whether this path is a socket.
        """
        try:
            return S_ISSOCK(self.stat().st_mode)
        except (OSError, ValueError):
            return False

    def samefile(self, other_path):
        """Return whether other_path is the same or not as this file
        (as returned by os.path.samefile()).
        """
        st = self.stat()
        try:
            other_st = other_path.stat()
        except AttributeError:
            other_st = self.with_segments(other_path).stat()
        return (st.st_ino == other_st.st_ino and
                st.st_dev == other_st.st_dev)

    def open(self, mode='r', buffering=-1, encoding=None,
             errors=None, newline=None):
        """
        Open the file pointed to by this path and return a file object, as
        the built-in open() function does.
        """
        if "b" not in mode:
            encoding = io.text_encoding(encoding)
        return io.open(self, mode, buffering, encoding, errors, newline)

    def read_bytes(self):
        """
        Open the file in bytes mode, read it, and close the file.
        """
        with self.open(mode='rb', buffering=0) as f:
            return f.read()

    def read_text(self, encoding=None, errors=None, newline=None):
        """
        Open the file in text mode, read it, and close the file.
        """
        # Call io.text_encoding() here to ensure any warning is raised at an
        # appropriate stack level.
        encoding = io.text_encoding(encoding)
        with self.open(mode='r', encoding=encoding, errors=errors, newline=newline) as f:
            return f.read()

    def write_bytes(self, data):
        """
        Open the file in bytes mode, write to it, and close the file.
        """
        # type-check for the buffer interface before truncating the file
        view = memoryview(data)
        with self.open(mode='wb') as f:
            return f.write(view)

    def write_text(self, data, encoding=None, errors=None, newline=None):
        """
        Open the file in text mode, write to it, and close the file.
        """
        # Call io.text_encoding() here to ensure any warning is raised at an
        # appropriate stack level.
        encoding = io.text_encoding(encoding)
        if not isinstance(data, str):
            raise TypeError('data must be str, not %s' %
                            data.__class__.__name__)
        with self.open(mode='w', encoding=encoding, errors=errors, newline=newline) as f:
            return f.write(data)

    _remove_leading_dot = operator.itemgetter(slice(2, None))
    _remove_trailing_slash = operator.itemgetter(slice(-1))

    def _filter_trailing_slash(self, paths):
        sep = self.parser.sep
        anchor_len = len(self.anchor)
        for path_str in paths:
            if len(path_str) > anchor_len and path_str[-1] == sep:
                path_str = path_str[:-1]
            yield path_str

    def _from_dir_entry(self, dir_entry, path_str):
        path = self.with_segments(path_str)
        path._str = path_str
        path._info = _Info(dir_entry.path, dir_entry)
        return path

    def iterdir(self):
        """Yield path objects of the directory contents.

        The children are yielded in arbitrary order, and the
        special entries '.' and '..' are not included.
        """
        root_dir = str(self)
        with os.scandir(root_dir) as scandir_it:
            entries = list(scandir_it)
        if root_dir == '.':
            return (self._from_dir_entry(e, e.name) for e in entries)
        else:
            return (self._from_dir_entry(e, e.path) for e in entries)

    def glob(self, pattern, *, case_sensitive=None, recurse_symlinks=False):
        """Iterate over this subtree and yield all existing files (of any
        kind, including directories) matching the given relative pattern.
        """
        sys.audit("pathlib.Path.glob", self, pattern)
        if case_sensitive is None:
            case_sensitive = self.parser is posixpath
            case_pedantic = False
        else:
            # The user has expressed a case sensitivity choice, but we don't
            # know the case sensitivity of the underlying filesystem, so we
            # must use scandir() for everything, including non-wildcard parts.
            case_pedantic = True
        parts = self._parse_pattern(pattern)
        recursive = True if recurse_symlinks else _no_recurse_symlinks
        globber = _StringGlobber(self.parser.sep, case_sensitive, case_pedantic, recursive)
        select = globber.selector(parts[::-1])
        root = str(self)
        paths = select(self.parser.join(root, ''))

        # Normalize results
        if root == '.':
            paths = map(self._remove_leading_dot, paths)
        if parts[-1] == '':
            paths = map(self._remove_trailing_slash, paths)
        elif parts[-1] == '**':
            paths = self._filter_trailing_slash(paths)
        paths = map(self._from_parsed_string, paths)
        return paths

    def rglob(self, pattern, *, case_sensitive=None, recurse_symlinks=False):
        """Recursively yield all existing files (of any kind, including
        directories) matching the given relative pattern, anywhere in
        this subtree.
        """
        sys.audit("pathlib.Path.rglob", self, pattern)
        pattern = self.parser.join('**', pattern)
        return self.glob(pattern, case_sensitive=case_sensitive, recurse_symlinks=recurse_symlinks)

    def walk(self, top_down=True, on_error=None, follow_symlinks=False):
        """Walk the directory tree from this directory, similar to os.walk()."""
        sys.audit("pathlib.Path.walk", self, on_error, follow_symlinks)
        root_dir = str(self)
        if not follow_symlinks:
            follow_symlinks = os._walk_symlinks_as_files
        results = os.walk(root_dir, top_down, on_error, follow_symlinks)
        for path_str, dirnames, filenames in results:
            if root_dir == '.':
                path_str = path_str[2:]
            yield self._from_parsed_string(path_str), dirnames, filenames

    def absolute(self):
        """Return an absolute version of this path
        No normalization or symlink resolution is performed.

        Use resolve() to resolve symlinks and remove '..' segments.
        """
        if self.is_absolute():
            return self
        if self.root:
            drive = os.path.splitroot(os.getcwd())[0]
            return self._from_parsed_parts(drive, self.root, self._tail)
        if self.drive:
            # There is a CWD on each drive-letter drive.
            cwd = os.path.abspath(self.drive)
        else:
            cwd = os.getcwd()
        if not self._tail:
            # Fast path for "empty" paths, e.g. Path("."), Path("") or Path().
            # We pass only one argument to with_segments() to avoid the cost
            # of joining, and we exploit the fact that getcwd() returns a
            # fully-normalized string by storing it in _str. This is used to
            # implement Path.cwd().
            return self._from_parsed_string(cwd)
        drive, root, rel = os.path.splitroot(cwd)
        if not rel:
            return self._from_parsed_parts(drive, root, self._tail)
        tail = rel.split(self.parser.sep)
        tail.extend(self._tail)
        return self._from_parsed_parts(drive, root, tail)

    @classmethod
    def cwd(cls):
        """Return a new path pointing to the current working directory."""
        cwd = os.getcwd()
        path = cls(cwd)
        path._str = cwd  # getcwd() returns a normalized path
        return path

    def resolve(self, strict=False):
        """
        Make the path absolute, resolving all symlinks on the way and also
        normalizing it.
        """

        return self.with_segments(os.path.realpath(self, strict=strict))

    if pwd:
        def owner(self, *, follow_symlinks=True):
            """
            Return the login name of the file owner.
            """
            uid = self.stat(follow_symlinks=follow_symlinks).st_uid
            return pwd.getpwuid(uid).pw_name
    else:
        def owner(self, *, follow_symlinks=True):
            """
            Return the login name of the file owner.
            """
            f = f"{type(self).__name__}.owner()"
            raise UnsupportedOperation(f"{f} is unsupported on this system")

    if grp:
        def group(self, *, follow_symlinks=True):
            """
            Return the group name of the file gid.
            """
            gid = self.stat(follow_symlinks=follow_symlinks).st_gid
            return grp.getgrgid(gid).gr_name
    else:
        def group(self, *, follow_symlinks=True):
            """
            Return the group name of the file gid.
            """
            f = f"{type(self).__name__}.group()"
            raise UnsupportedOperation(f"{f} is unsupported on this system")

    if hasattr(os, "readlink"):
        def readlink(self):
            """
            Return the path to which the symbolic link points.
            """
            return self.with_segments(os.readlink(self))
    else:
        def readlink(self):
            """
            Return the path to which the symbolic link points.
            """
            f = f"{type(self).__name__}.readlink()"
            raise UnsupportedOperation(f"{f} is unsupported on this system")

    def touch(self, mode=0o666, exist_ok=True):
        """
        Create this file with the given access mode, if it doesn't exist.
        """

        if exist_ok:
            # First try to bump modification time
            # Implementation note: GNU touch uses the UTIME_NOW option of
            # the utimensat() / futimens() functions.
            try:
                os.utime(self, None)
            except OSError:
                # Avoid exception chaining
                pass
            else:
                return
        flags = os.O_CREAT | os.O_WRONLY
        if not exist_ok:
            flags |= os.O_EXCL
        fd = os.open(self, flags, mode)
        os.close(fd)

    def mkdir(self, mode=0o777, parents=False, exist_ok=False, *, parent_mode=None):
        """
        Create a new directory at this given path.
        """
        try:
            os.mkdir(self, mode)
        except FileNotFoundError:
            if not parents or self.parent == self:
                raise
            if parent_mode is not None:
                self.parent.mkdir(mode=parent_mode, parents=True, exist_ok=True,
                                  parent_mode=parent_mode)
            else:
                self.parent.mkdir(parents=True, exist_ok=True)
            self.mkdir(mode, parents=False, exist_ok=exist_ok)
        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 self.is_dir():
                raise

    def chmod(self, mode, *, follow_symlinks=True):
        """
        Change the permissions of the path, like os.chmod().
        """
        os.chmod(self, mode, follow_symlinks=follow_symlinks)

    def lchmod(self, mode):
        """
        Like chmod(), except if the path points to a symlink, the symlink's
        permissions are changed, rather than its target's.
        """
        self.chmod(mode, follow_symlinks=False)

    def unlink(self, missing_ok=False):
        """
        Remove this file or link.
        If the path is a directory, use rmdir() instead.
        """
        try:
            os.unlink(self)
        except FileNotFoundError:
            if not missing_ok:
                raise

    def rmdir(self):
        """
        Remove this directory.  The directory must be empty.
        """
        os.rmdir(self)

    def _delete(self):
        """
        Delete this file or directory (including all sub-directories).
        """
        if self.is_symlink() or self.is_junction():
            self.unlink()
        elif self.is_dir():
            shutil.rmtree(self)
        else:
            self.unlink()

    def rename(self, target):
        """
        Rename this path to the target path.

        The target path may be absolute or relative. Relative paths are
        interpreted relative to the current working directory, *not* the
        directory of the Path object.

        Returns the new Path instance pointing to the target path.
        """
        os.rename(self, target)
        if not hasattr(target, 'with_segments'):
            target = self.with_segments(target)
        return target

    def replace(self, target):
        """
        Rename this path to the target path, overwriting if that path exists.

        The target path may be absolute or relative. Relative paths are
        interpreted relative to the current working directory, *not* the
        directory of the Path object.

        Returns the new Path instance pointing to the target path.
        """
        os.replace(self, target)
        if not hasattr(target, 'with_segments'):
            target = self.with_segments(target)
        return target

    def copy(self, target, **kwargs):
        """
        Recursively copy this file or directory tree to the given destination.
        """
        if not hasattr(target, 'with_segments'):
            target = self.with_segments(target)
        ensure_distinct_paths(self, target)
        target._copy_from(self, **kwargs)
        return target.joinpath()  # Empty join to ensure fresh metadata.

    def copy_into(self, target_dir, **kwargs):
        """
        Copy this file or directory tree into the given existing directory.
        """
        name = self.name
        if not name:
            raise ValueError(f"{self!r} has an empty name")
        elif hasattr(target_dir, 'with_segments'):
            target = target_dir / name
        else:
            target = self.with_segments(target_dir, name)
        return self.copy(target, **kwargs)

    def _copy_from(self, source, follow_symlinks=True, preserve_metadata=False):
        """
        Recursively copy the given path to this path.
        """
        if not follow_symlinks and source.info.is_symlink():
            self._copy_from_symlink(source, preserve_metadata)
        elif source.info.is_dir():
            children = source.iterdir()
            os.mkdir(self)
            for child in children:
                self.joinpath(child.name)._copy_from(
                    child, follow_symlinks, preserve_metadata)
            if preserve_metadata:
                _copy_info(source.info, self)
        else:
            self._copy_from_file(source, preserve_metadata)

    def _copy_from_file(self, source, preserve_metadata=False):
        ensure_different_files(source, self)
        with vfsopen(source, 'rb') as source_f:
            with open(self, 'wb') as target_f:
                copyfileobj(source_f, target_f)
        if preserve_metadata:
            _copy_info(source.info, self)

    if copyfile2:
        # Use fast OS routine for local file copying where available.
        _copy_from_file_fallback = _copy_from_file
        def _copy_from_file(self, source, preserve_metadata=False):
            try:
                source = os.fspath(source)
            except TypeError:
                pass
            else:
                copyfile2(source, str(self))
                return
            self._copy_from_file_fallback(source, preserve_metadata)

    if os.name == 'nt':
        # If a directory-symlink is copied *before* its target, then
        # os.symlink() incorrectly creates a file-symlink on Windows. Avoid
        # this by passing *target_is_dir* to os.symlink() on Windows.
        def _copy_from_symlink(self, source, preserve_metadata=False):
            os.symlink(vfspath(source.readlink()), self, source.info.is_dir())
            if preserve_metadata:
                _copy_info(source.info, self, follow_symlinks=False)
    else:
        def _copy_from_symlink(self, source, preserve_metadata=False):
            os.symlink(vfspath(source.readlink()), self)
            if preserve_metadata:
                _copy_info(source.info, self, follow_symlinks=False)

    def move(self, target):
        """
        Recursively move this file or directory tree to the given destination.
        """
        # Use os.replace() if the target is os.PathLike and on the same FS.
        try:
            target = self.with_segments(target)
        except TypeError:
            pass
        else:
            ensure_different_files(self, target)
            try:
                os.replace(self, target)
            except OSError as err:
                if err.errno != EXDEV:
                    raise
            else:
                return target.joinpath()  # Empty join to ensure fresh metadata.
        # Fall back to copy+delete.
        target = self.copy(target, follow_symlinks=False, preserve_metadata=True)
        self._delete()
        return target

    def move_into(self, target_dir):
        """
        Move this file or directory tree into the given existing directory.
        """
        name = self.name
        if not name:
            raise ValueError(f"{self!r} has an empty name")
        elif hasattr(target_dir, 'with_segments'):
            target = target_dir / name
        else:
            target = self.with_segments(target_dir, name)
        return self.move(target)

    if hasattr(os, "symlink"):
        def symlink_to(self, target, target_is_directory=False):
            """
            Make this path a symlink pointing to the target path.
            Note the order of arguments (link, target) is the reverse of os.symlink.
            """
            os.symlink(target, self, target_is_directory)
    else:
        def symlink_to(self, target, target_is_directory=False):
            """
            Make this path a symlink pointing to the target path.
            Note the order of arguments (link, target) is the reverse of os.symlink.
            """
            f = f"{type(self).__name__}.symlink_to()"
            raise UnsupportedOperation(f"{f} is unsupported on this system")

    if hasattr(os, "link"):
        def hardlink_to(self, target):
            """
            Make this path a hard link pointing to the same file as *target*.

            Note the order of arguments (self, target) is the reverse of os.link's.
            """
            os.link(target, self)
    else:
        def hardlink_to(self, target):
            """
            Make this path a hard link pointing to the same file as *target*.

            Note the order of arguments (self, target) is the reverse of os.link's.
            """
            f = f"{type(self).__name__}.hardlink_to()"
            raise UnsupportedOperation(f"{f} is unsupported on this system")

    def expanduser(self):
        """ Return a new path with expanded ~ and ~user constructs
        (as returned by os.path.expanduser)
        """
        if (not (self.drive or self.root) and
            self._tail and self._tail[0][:1] == '~'):
            homedir = os.path.expanduser(self._tail[0])
            if homedir[:1] == "~":
                raise RuntimeError("Could not determine home directory.")
            drv, root, tail = self._parse_path(homedir)
            return self._from_parsed_parts(drv, root, tail + self._tail[1:])

        return self

    @classmethod
    def home(cls):
        """Return a new path pointing to expanduser('~').
        """
        homedir = os.path.expanduser("~")
        if homedir == "~":
            raise RuntimeError("Could not determine home directory.")
        return cls(homedir)

    def as_uri(self):
        """Return the path as a URI."""
        if not self.is_absolute():
            raise ValueError("relative paths can't be expressed as file URIs")
        from urllib.request import pathname2url
        return pathname2url(str(self), add_scheme=True)

    @classmethod
    def from_uri(cls, uri):
        """Return a new path from the given 'file' URI."""
        from urllib.error import URLError
        from urllib.request import url2pathname
        try:
            path = cls(url2pathname(uri, require_scheme=True))
        except URLError as exc:
            raise ValueError(exc.reason) from None
        if not path.is_absolute():
            raise ValueError(f"URI is not absolute: {uri!r}")
        return path


class PosixPath(Path, PurePosixPath):
    """Path subclass for non-Windows systems.

    On a POSIX system, instantiating a Path should return this object.
    """
    __slots__ = ()

    if os.name == 'nt':
        def __new__(cls, *args, **kwargs):
            raise UnsupportedOperation(
                f"cannot instantiate {cls.__name__!r} on your system")

class WindowsPath(Path, PureWindowsPath):
    """Path subclass for Windows systems.

    On a Windows system, instantiating a Path should return this object.
    """
    __slots__ = ()

    if os.name != 'nt':
        def __new__(cls, *args, **kwargs):
            raise UnsupportedOperation(
                f"cannot instantiate {cls.__name__!r} on your system")
