"""Utility functions for copying and archiving files and directory trees.

XXX The functions here don't copy the resource fork or other metadata on Mac.

"""

import os
import sys
import stat
import fnmatch
import collections
import errno

try:
 import zlib
 del zlib
 _ZLIB_SUPPORTED = True
except ImportError:
 _ZLIB_SUPPORTED = False

try:
 import bz2
 del bz2
 _BZ2_SUPPORTED = True
except ImportError:
 _BZ2_SUPPORTED = False

try:
 import lzma
 del lzma
 _LZMA_SUPPORTED = True
except ImportError:
 _LZMA_SUPPORTED = False

try:
 from pwd import getpwnam
except ImportError:
 getpwnam = None

try:
 from grp import getgrnam
except ImportError:
 getgrnam = None

_WINDOWS = os.name == 'nt'
posix = nt = None
if os.name == 'posix':
 import posix
elif _WINDOWS:
 import nt

COPY_BUFSIZE = 1024 * 1024 if _WINDOWS else 64 * 1024
_USE_CP_SENDFILE = hasattr(os, "sendfile") and sys.platform.startswith("linux")
_HAS_FCOPYFILE = posix and hasattr(posix, "_fcopyfile") # macOS

# CMD defaults in Windows 10
_WIN_DEFAULT_PATHEXT = ".COM;.EXE;.BAT;.CMD;.VBS;.JS;.WS;.MSC"

__all__ = ["copyfileobj", "copyfile", "copymode", "copystat", "copy", "copy2",
 "copytree", "move", "rmtree", "Error", "SpecialFileError",
 "ExecError", "make_archive", "get_archive_formats",
 "register_archive_format", "unregister_archive_format",
 "get_unpack_formats", "register_unpack_format",
 "unregister_unpack_format", "unpack_archive",
 "ignore_patterns", "chown", "which", "get_terminal_size",
 "SameFileError"]
 # disk_usage is added later, if available on the platform

class Error(OSError):
 pass

class SameFileError(Error):
 """Raised when source and destination are the same file."""

class SpecialFileError(OSError):
 """Raised when trying to do a kind of operation (e.g. copying) which is
 not supported on a special file (e.g. a named pipe)"""

class ExecError(OSError):
 """Raised when a command could not be executed"""

class ReadError(OSError):
 """Raised when an archive cannot be read"""

class RegistryError(Exception):
 """Raised when a registry operation with the archiving
 and unpacking registries fails"""

class _GiveupOnFastCopy(Exception):
 """Raised as a signal to fallback on using raw read()/write()
 file copy when fast-copy functions fail to do so.
 """

def _fastcopy_fcopyfile(fsrc, fdst, flags):
 """Copy a regular file content or metadata by using high-performance
 fcopyfile(3) syscall (macOS).
 """
 try:
 infd = fsrc.fileno()
 outfd = fdst.fileno()
 except Exception as err:
 raise _GiveupOnFastCopy(err) # not a regular file

 try:
 posix._fcopyfile(infd, outfd, flags)
 except OSError as err:
 err.filename = fsrc.name
 err.filename2 = fdst.name
 if err.errno in {errno.EINVAL, errno.ENOTSUP}:
 raise _GiveupOnFastCopy(err)
 else:
 raise err from None

def _fastcopy_sendfile(fsrc, fdst):
 """Copy data from one regular mmap-like fd to another by using
 high-performance sendfile(2) syscall.
 This should work on Linux >= 2.6.33 only.
 """
 # Note: copyfileobj() is left alone in order to not introduce any
 # unexpected breakage. Possible risks by using zero-copy calls
 # in copyfileobj() are:
 # - fdst cannot be open in "a"(ppend) mode
 # - fsrc and fdst may be open in "t"(ext) mode
 # - fsrc may be a BufferedReader (which hides unread data in a buffer),
 # GzipFile (which decompresses data), HTTPResponse (which decodes
 # chunks).
 # - possibly others (e.g. encrypted fs/partition?)
 global _USE_CP_SENDFILE
 try:
 infd = fsrc.fileno()
 outfd = fdst.fileno()
 except Exception as err:
 raise _GiveupOnFastCopy(err) # not a regular file

 # Hopefully the whole file will be copied in a single call.
 # sendfile() is called in a loop 'till EOF is reached (0 return)
 # so a bufsize smaller or bigger than the actual file size
 # should not make any difference, also in case the file content
 # changes while being copied.
 try:
 blocksize = max(os.fstat(infd).st_size, 2 ** 23) # min 8MiB
 except OSError:
 blocksize = 2 ** 27 # 128MiB
 # On 32-bit architectures truncate to 1GiB to avoid OverflowError,
 # see bpo-38319.
 if sys.maxsize < 2 ** 32:
 blocksize = min(blocksize, 2 ** 30)

 offset = 0
 while True:
 try:
 sent = os.sendfile(outfd, infd, offset, blocksize)
 except OSError as err:
 # ...in oder to have a more informative exception.
 err.filename = fsrc.name
 err.filename2 = fdst.name

 if err.errno == errno.ENOTSOCK:
 # sendfile() on this platform (probably Linux < 2.6.33)
 # does not support copies between regular files (only
 # sockets).
 _USE_CP_SENDFILE = False
 raise _GiveupOnFastCopy(err)

 if err.errno == errno.ENOSPC: # filesystem is full
 raise err from None

 # Give up on first call and if no data was copied.
 if offset == 0 and os.lseek(outfd, 0, os.SEEK_CUR) == 0:
 raise _GiveupOnFastCopy(err)

 raise err
 else:
 if sent == 0:
 break # EOF
 offset += sent

def _copyfileobj_readinto(fsrc, fdst, length=COPY_BUFSIZE):
 """readinto()/memoryview() based variant of copyfileobj().
 *fsrc* must support readinto() method and both files must be
 open in binary mode.
 """
 # Localize variable access to minimize overhead.
 fsrc_readinto = fsrc.readinto
 fdst_write = fdst.write
 with memoryview(bytearray(length)) as mv:
 while True:
 n = fsrc_readinto(mv)
 if not n:
 break
 elif n < length:
 with mv[:n] as smv:
 fdst.write(smv)
 else:
 fdst_write(mv)

def copyfileobj(fsrc, fdst, length=0):
 """copy data from file-like object fsrc to file-like object fdst"""
 # Localize variable access to minimize overhead.
 if not length:
 length = COPY_BUFSIZE
 fsrc_read = fsrc.read
 fdst_write = fdst.write
 while True:
 buf = fsrc_read(length)
 if not buf:
 break
 fdst_write(buf)

def _samefile(src, dst):
 # Macintosh, Unix.
 if isinstance(src, os.DirEntry) and hasattr(os.path, 'samestat'):
 try:
 return os.path.samestat(src.stat(), os.stat(dst))
 except OSError:
 return False

 if hasattr(os.path, 'samefile'):
 try:
 return os.path.samefile(src, dst)
 except OSError:
 return False

 # All other platforms: check for same pathname.
 return (os.path.normcase(os.path.abspath(src)) ==
 os.path.normcase(os.path.abspath(dst)))

def _stat(fn):
 return fn.stat() if isinstance(fn, os.DirEntry) else os.stat(fn)

def _islink(fn):
 return fn.is_symlink() if isinstance(fn, os.DirEntry) else os.path.islink(fn)

def copyfile(src, dst, *, follow_symlinks=True):
 """Copy data from src to dst in the most efficient way possible.

 If follow_symlinks is not set and src is a symbolic link, a new
 symlink will be created instead of copying the file it points to.

 """
 sys.audit("shutil.copyfile", src, dst)

 if _samefile(src, dst):
 raise SameFileError("{!r} and {!r} are the same file".format(src, dst))

 file_size = 0
 for i, fn in enumerate([src, dst]):
 try:
 st = _stat(fn)
 except OSError:
 # File most likely does not exist
 pass
 else:
 # XXX What about other special files? (sockets, devices...)
 if stat.S_ISFIFO(st.st_mode):
 fn = fn.path if isinstance(fn, os.DirEntry) else fn
 raise SpecialFileError("`%s` is a named pipe" % fn)
 if _WINDOWS and i == 0:
 file_size = st.st_size

 if not follow_symlinks and _islink(src):
 os.symlink(os.readlink(src), dst)
 else:
 with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
 # macOS
 if _HAS_FCOPYFILE:
 try:
 _fastcopy_fcopyfile(fsrc, fdst, posix._COPYFILE_DATA)
 return dst
 except _GiveupOnFastCopy:
 pass
 # Linux
 elif _USE_CP_SENDFILE:
 try:
 _fastcopy_sendfile(fsrc, fdst)
 return dst
 except _GiveupOnFastCopy:
 pass
 # Windows, see:
 # https://github.com/python/cpython/pull/7160#discussion_r195405230
 elif _WINDOWS and file_size > 0:
 _copyfileobj_readinto(fsrc, fdst, min(file_size, COPY_BUFSIZE))
 return dst

 copyfileobj(fsrc, fdst)

 return dst

def copymode(src, dst, *, follow_symlinks=True):
 """Copy mode bits from src to dst.

 If follow_symlinks is not set, symlinks aren't followed if and only
 if both `src` and `dst` are symlinks. If `lchmod` isn't available
 (e.g. Linux) this method does nothing.

 """
 sys.audit("shutil.copymode", src, dst)

 if not follow_symlinks and _islink(src) and os.path.islink(dst):
 if hasattr(os, 'lchmod'):
 stat_func, chmod_func = os.lstat, os.lchmod
 else:
 return
 else:
 stat_func, chmod_func = _stat, os.chmod

 st = stat_func(src)
 chmod_func(dst, stat.S_IMODE(st.st_mode))

if hasattr(os, 'listxattr'):
 def _copyxattr(src, dst, *, follow_symlinks=True):
 """Copy extended filesystem attributes from `src` to `dst`.

 Overwrite existing attributes.

 If `follow_symlinks` is false, symlinks won't be followed.

 """

 try:
 names = os.listxattr(src, follow_symlinks=follow_symlinks)
 except OSError as e:
 if e.errno not in (errno.ENOTSUP, errno.ENODATA, errno.EINVAL):
 raise
 return
 for name in names:
 try:
 value = os.getxattr(src, name, follow_symlinks=follow_symlinks)
 os.setxattr(dst, name, value, follow_symlinks=follow_symlinks)
 except OSError as e:
 if e.errno not in (errno.EPERM, errno.ENOTSUP, errno.ENODATA,
 errno.EINVAL):
 raise
else:
 def _copyxattr(*args, **kwargs):
 pass

def copystat(src, dst, *, follow_symlinks=True):
 """Copy file metadata

 Copy the permission bits, last access time, last modification time, and
 flags from `src` to `dst`. On Linux, copystat() also copies the "extended
 attributes" where possible. The file contents, owner, and group are
 unaffected. `src` and `dst` are path-like objects or path names given as
 strings.

 If the optional flag `follow_symlinks` is not set, symlinks aren't
 followed if and only if both `src` and `dst` are symlinks.
 """
 sys.audit("shutil.copystat", src, dst)

 def _nop(*args, ns=None, follow_symlinks=None):
 pass

 # follow symlinks (aka don't not follow symlinks)
 follow = follow_symlinks or not (_islink(src) and os.path.islink(dst))
 if follow:
 # use the real function if it exists
 def lookup(name):
 return getattr(os, name, _nop)
 else:
 # use the real function only if it exists
 # *and* it supports follow_symlinks
 def lookup(name):
 fn = getattr(os, name, _nop)
 if fn in os.supports_follow_symlinks:
 return fn
 return _nop

 if isinstance(src, os.DirEntry):
 st = src.stat(follow_symlinks=follow)
 else:
 st = lookup("stat")(src, follow_symlinks=follow)
 mode = stat.S_IMODE(st.st_mode)
 lookup("utime")(dst, ns=(st.st_atime_ns, st.st_mtime_ns),
 follow_symlinks=follow)
 # We must copy extended attributes before the file is (potentially)
 # chmod()'ed read-only, otherwise setxattr() will error with -EACCES.
 _copyxattr(src, dst, follow_symlinks=follow)
 try:
 lookup("chmod")(dst, mode, follow_symlinks=follow)
 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
 if hasattr(st, 'st_flags'):
 try:
 lookup("chflags")(dst, st.st_flags, follow_symlinks=follow)
 except OSError as why:
 for err in 'EOPNOTSUPP', 'ENOTSUP':
 if hasattr(errno, err) and why.errno == getattr(errno, err):
 break
 else:
 raise

def copy(src, dst, *, follow_symlinks=True):
 """Copy data and mode bits ("cp src dst"). Return the file's destination.

 The destination may be a directory.

 If follow_symlinks is false, symlinks won't be followed. This
 resembles GNU's "cp -P src dst".

 If source and destination are the same file, a SameFileError will be
 raised.

 """
 if os.path.isdir(dst):
 dst = os.path.join(dst, os.path.basename(src))
 copyfile(src, dst, follow_symlinks=follow_symlinks)
 copymode(src, dst, follow_symlinks=follow_symlinks)
 return dst

def copy2(src, dst, *, follow_symlinks=True):
 """Copy data and metadata. Return the file's destination.

 Metadata is copied with copystat(). Please see the copystat function
 for more information.

 The destination may be a directory.

 If follow_symlinks is false, symlinks won't be followed. This
 resembles GNU's "cp -P src dst".
 """
 if os.path.isdir(dst):
 dst = os.path.join(dst, os.path.basename(src))
 copyfile(src, dst, follow_symlinks=follow_symlinks)
 copystat(src, dst, follow_symlinks=follow_symlinks)
 return dst

def ignore_patterns(*patterns):
 """Function that can be used as copytree() ignore parameter.

 Patterns is a sequence of glob-style patterns
 that are used to exclude files"""
 def _ignore_patterns(path, names):
 ignored_names = []
 for pattern in patterns:
 ignored_names.extend(fnmatch.filter(names, pattern))
 return set(ignored_names)
 return _ignore_patterns

def _copytree(entries, src, dst, symlinks, ignore, copy_function,
 ignore_dangling_symlinks, dirs_exist_ok=False):
 if ignore is not None:
 ignored_names = ignore(os.fspath(src), [x.name for x in entries])
 else:
 ignored_names = set()

 os.makedirs(dst, exist_ok=dirs_exist_ok)
 errors = []
 use_srcentry = copy_function is copy2 or copy_function is copy

 for srcentry in entries:
 if srcentry.name in ignored_names:
 continue
 srcname = os.path.join(src, srcentry.name)
 dstname = os.path.join(dst, srcentry.name)
 srcobj = srcentry if use_srcentry else srcname
 try:
 is_symlink = srcentry.is_symlink()
 if is_symlink and os.name == 'nt':
 # Special check for directory junctions, which appear as
 # symlinks but we want to recurse.
 lstat = srcentry.stat(follow_symlinks=False)
 if lstat.st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT:
 is_symlink = False
 if is_symlink:
 linkto = os.readlink(srcname)
 if symlinks:
 # We can't just leave it to `copy_function` because legacy
 # code with a custom `copy_function` may rely on copytree
 # doing the right thing.
 os.symlink(linkto, dstname)
 copystat(srcobj, dstname, follow_symlinks=not symlinks)
 else:
 # ignore dangling symlink if the flag is on
 if not os.path.exists(linkto) and ignore_dangling_symlinks:
 continue
 # otherwise let the copy occur. copy2 will raise an error
 if srcentry.is_dir():
 copytree(srcobj, dstname, symlinks, ignore,
 copy_function, dirs_exist_ok=dirs_exist_ok)
 else:
 copy_function(srcobj, dstname)
 elif srcentry.is_dir():
 copytree(srcobj, dstname, symlinks, ignore, copy_function,
 dirs_exist_ok=dirs_exist_ok)
 else:
 # Will raise a SpecialFileError for unsupported file types
 copy_function(srcobj, dstname)
 # catch the Error from the recursive copytree so that we can
 # continue with other files
 except Error as err:
 errors.extend(err.args[0])
 except OSError as why:
 errors.append((srcname, dstname, str(why)))
 try:
 copystat(src, dst)
 except OSError as why:
 # Copying file access times may fail on Windows
 if getattr(why, 'winerror', None) is None:
 errors.append((src, dst, str(why)))
 if errors:
 raise Error(errors)
 return dst

def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
 ignore_dangling_symlinks=False, dirs_exist_ok=False):
 """Recursively copy a directory tree and return the destination directory.

 dirs_exist_ok dictates whether to raise an exception in case dst or any
 missing parent directory already exists.

 If exception(s) occur, an Error is raised with a list of reasons.

 If the optional symlinks flag is true, symbolic links in the
 source tree result in symbolic links in the destination tree; if
 it is false, the contents of the files pointed to by symbolic
 links are copied. If the file pointed by the symlink doesn't
 exist, an exception will be added in the list of errors raised in
 an Error exception at the end of the copy process.

 You can set the optional ignore_dangling_symlinks flag to true if you
 want to silence this exception. Notice that this has no effect on
 platforms that don't support os.symlink.

 The optional ignore argument is a callable. If given, it
 is called with the `src` parameter, which is the directory
 being visited by copytree(), and `names` which is the list of
 `src` contents, as returned by os.listdir():

 callable(src, names) -> ignored_names

 Since copytree() is called recursively, the callable will be
 called once for each directory that is copied. It returns a
 list of names relative to the `src` directory that should
 not be copied.

 The optional copy_function argument is a callable that will be used
 to copy each file. It will be called with the source path and the
 destination path as arguments. By default, copy2() is used, but any
 function that supports the same signature (like copy()) can be used.

 """
 sys.audit("shutil.copytree", src, dst)
 with os.scandir(src) as itr:
 entries = list(itr)
 return _copytree(entries=entries, src=src, dst=dst, symlinks=symlinks,
 ignore=ignore, copy_function=copy_function,
 ignore_dangling_symlinks=ignore_dangling_symlinks,
 dirs_exist_ok=dirs_exist_ok)

if hasattr(os.stat_result, 'st_file_attributes'):
 # Special handling for directory junctions to make them behave like
 # symlinks for shutil.rmtree, since in general they do not appear as
 # regular links.
 def _rmtree_isdir(entry):
 try:
 st = entry.stat(follow_symlinks=False)
 return (stat.S_ISDIR(st.st_mode) and not
 (st.st_file_attributes & stat.FILE_ATTRIBUTE_REPARSE_POINT
 and st.st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT))
 except OSError:
 return False

 def _rmtree_islink(path):
 try:
 st = os.lstat(path)
 return (stat.S_ISLNK(st.st_mode) or
 (st.st_file_attributes & stat.FILE_ATTRIBUTE_REPARSE_POINT
 and st.st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT))
 except OSError:
 return False
else:
 def _rmtree_isdir(entry):
 try:
 return entry.is_dir(follow_symlinks=False)
 except OSError:
 return False

 def _rmtree_islink(path):
 return os.path.islink(path)

# version vulnerable to race conditions
def _rmtree_unsafe(path, onerror):
 try:
 with os.scandir(path) as scandir_it:
 entries = list(scandir_it)
 except OSError:
 onerror(os.scandir, path, sys.exc_info())
 entries = []
 for entry in entries:
 fullname = entry.path
 if _rmtree_isdir(entry):
 try:
 if entry.is_symlink():
 # This can only happen if someone replaces
 # a directory with a symlink after the call to
 # os.scandir or entry.is_dir above.
 raise OSError("Cannot call rmtree on a symbolic link")
 except OSError:
 onerror(os.path.islink, fullname, sys.exc_info())
 continue
 _rmtree_unsafe(fullname, onerror)
 else:
 try:
 os.unlink(fullname)
 except OSError:
 onerror(os.unlink, fullname, sys.exc_info())
 try:
 os.rmdir(path)
 except OSError:
 onerror(os.rmdir, path, sys.exc_info())

# Version using fd-based APIs to protect against races
def _rmtree_safe_fd(topfd, path, onerror):
 try:
 with os.scandir(topfd) as scandir_it:
 entries = list(scandir_it)
 except OSError as err:
 err.filename = path
 onerror(os.scandir, path, sys.exc_info())
 return
 for entry in entries:
 fullname = os.path.join(path, entry.name)
 try:
 is_dir = entry.is_dir(follow_symlinks=False)
 except OSError:
 is_dir = False
 else:
 if is_dir:
 try:
 orig_st = entry.stat(follow_symlinks=False)
 is_dir = stat.S_ISDIR(orig_st.st_mode)
 except OSError:
 onerror(os.lstat, fullname, sys.exc_info())
 continue
 if is_dir:
 try:
 dirfd = os.open(entry.name, os.O_RDONLY, dir_fd=topfd)
 except OSError:
 onerror(os.open, fullname, sys.exc_info())
 else:
 try:
 if os.path.samestat(orig_st, os.fstat(dirfd)):
 _rmtree_safe_fd(dirfd, fullname, onerror)
 try:
 os.rmdir(entry.name, dir_fd=topfd)
 except OSError:
 onerror(os.rmdir, fullname, sys.exc_info())
 else:
 try:
 # This can only happen if someone replaces
 # a directory with a symlink after the call to
 # os.scandir or stat.S_ISDIR above.
 raise OSError("Cannot call rmtree on a symbolic "
 "link")
 except OSError:
 onerror(os.path.islink, fullname, sys.exc_info())
 finally:
 os.close(dirfd)
 else:
 try:
 os.unlink(entry.name, dir_fd=topfd)
 except OSError:
 onerror(os.unlink, fullname, sys.exc_info())

_use_fd_functions = ({os.open, os.stat, os.unlink, os.rmdir} <=
 os.supports_dir_fd and
 os.scandir in os.supports_fd and
 os.stat in os.supports_follow_symlinks)

def rmtree(path, ignore_errors=False, onerror=None):
 """Recursively delete a directory tree.

 If ignore_errors is set, errors are ignored; otherwise, if onerror
 is set, it is called to handle the error with arguments (func,
 path, exc_info) where func is platform and implementation dependent;
 path is the argument to that function that caused it to fail; and
 exc_info is a tuple returned by sys.exc_info(). If ignore_errors
 is false and onerror is None, an exception is raised.

 """
 sys.audit("shutil.rmtree", path)
 if ignore_errors:
 def onerror(*args):
 pass
 elif onerror is None:
 def onerror(*args):
 raise
 if _use_fd_functions:
 # While the unsafe rmtree works fine on bytes, the fd based does not.
 if isinstance(path, bytes):
 path = os.fsdecode(path)
 # Note: To guard against symlink races, we use the standard
 # lstat()/open()/fstat() trick.
 try:
 orig_st = os.lstat(path)
 except Exception:
 onerror(os.lstat, path, sys.exc_info())
 return
 try:
 fd = os.open(path, os.O_RDONLY)
 except Exception:
 onerror(os.open, path, sys.exc_info())
 return
 try:
 if os.path.samestat(orig_st, os.fstat(fd)):
 _rmtree_safe_fd(fd, path, onerror)
 try:
 os.rmdir(path)
 except OSError:
 onerror(os.rmdir, path, sys.exc_info())
 else:
 try:
 # symlinks to directories are forbidden, see bug #1669
 raise OSError("Cannot call rmtree on a symbolic link")
 except OSError:
 onerror(os.path.islink, path, sys.exc_info())
 finally:
 os.close(fd)
 else:
 try:
 if _rmtree_islink(path):
 # symlinks to directories are forbidden, see bug #1669
 raise OSError("Cannot call rmtree on a symbolic link")
 except OSError:
 onerror(os.path.islink, path, sys.exc_info())
 # can't continue even if onerror hook returns
 return
 return _rmtree_unsafe(path, onerror)

# Allow introspection of whether or not the hardening against symlink
# attacks is supported on the current platform
rmtree.avoids_symlink_attacks = _use_fd_functions

def _basename(path):
 # A basename() variant which first strips the trailing slash, if present.
 # Thus we always get the last component of the path, even for directories.
 sep = os.path.sep + (os.path.altsep or '')
 return os.path.basename(path.rstrip(sep))

def move(src, dst, copy_function=copy2):
 """Recursively move a file or directory to another location. This is
 similar to the Unix "mv" command. Return the file or directory's
 destination.

 If the destination is a directory or a symlink to a directory, the source
 is moved inside the directory. The destination path must not already
 exist.

 If the destination already exists but is not a directory, it may be
 overwritten depending on os.rename() semantics.

 If the destination is on our current filesystem, then rename() is used.
 Otherwise, src is copied to the destination and then removed. Symlinks are
 recreated under the new name if os.rename() fails because of cross
 filesystem renames.

 The optional `copy_function` argument is a callable that will be used
 to copy the source or it will be delegated to `copytree`.
 By default, copy2() is used, but any function that supports the same
 signature (like copy()) can be used.

 A lot more could be done here... A look at a mv.c shows a lot of
 the issues this implementation glosses over.

 """
 sys.audit("shutil.move", src, dst)
 real_dst = dst
 if os.path.isdir(dst):
 if _samefile(src, dst):
 # We might be on a case insensitive filesystem,
 # perform the rename anyway.
 os.rename(src, dst)
 return

 real_dst = os.path.join(dst, _basename(src))
 if os.path.exists(real_dst):
 raise Error("Destination path '%s' already exists" % real_dst)
 try:
 os.rename(src, real_dst)
 except OSError:
 if os.path.islink(src):
 linkto = os.readlink(src)
 os.symlink(linkto, real_dst)
 os.unlink(src)
 elif os.path.isdir(src):
 if _destinsrc(src, dst):
 raise Error("Cannot move a directory '%s' into itself"
 " '%s'." % (src, dst))
 if (_is_immutable(src)
 or (not os.access(src, os.W_OK) and os.listdir(src)
 and sys.platform == 'darwin')):
 raise PermissionError("Cannot move the non-empty directory "
 "'%s': Lacking write permission to '%s'."
 % (src, src))
 copytree(src, real_dst, copy_function=copy_function,
 symlinks=True)
 rmtree(src)
 else:
 copy_function(src, real_dst)
 os.unlink(src)
 return real_dst

def _destinsrc(src, dst):
 src = os.path.abspath(src)
 dst = os.path.abspath(dst)
 if not src.endswith(os.path.sep):
 src += os.path.sep
 if not dst.endswith(os.path.sep):
 dst += os.path.sep
 return dst.startswith(src)

def _is_immutable(src):
 st = _stat(src)
 immutable_states = [stat.UF_IMMUTABLE, stat.SF_IMMUTABLE]
 return hasattr(st, 'st_flags') and st.st_flags in immutable_states

def _get_gid(name):
 """Returns a gid, given a group name."""
 if getgrnam is None or name is None:
 return None
 try:
 result = getgrnam(name)
 except KeyError:
 result = None
 if result is not None:
 return result[2]
 return None

def _get_uid(name):
 """Returns an uid, given a user name."""
 if getpwnam is None or name is None:
 return None
 try:
 result = getpwnam(name)
 except KeyError:
 result = None
 if result is not None:
 return result[2]
 return None

def _make_tarball(base_name, base_dir, compress="gzip", verbose=0, dry_run=0,
 owner=None, group=None, logger=None):
 """Create a (possibly compressed) tar file from all the files under
 'base_dir'.

 'compress' must be "gzip" (the default), "bzip2", "xz", or None.

 'owner' and 'group' can be used to define an owner and a group for the
 archive that is being built. If not provided, the current owner and group
 will be used.

 The output tar file will be named 'base_name' + ".tar", possibly plus
 the appropriate compression extension (".gz", ".bz2", or ".xz").

 Returns the output filename.
 """
 if compress is None:
 tar_compression = ''
 elif _ZLIB_SUPPORTED and compress == 'gzip':
 tar_compression = 'gz'
 elif _BZ2_SUPPORTED and compress == 'bzip2':
 tar_compression = 'bz2'
 elif _LZMA_SUPPORTED and compress == 'xz':
 tar_compression = 'xz'
 else:
 raise ValueError("bad value for 'compress', or compression format not "
 "supported : {0}".format(compress))

 import tarfile # late import for breaking circular dependency

 compress_ext = '.' + tar_compression if compress else ''
 archive_name = base_name + '.tar' + compress_ext
 archive_dir = os.path.dirname(archive_name)

 if archive_dir and not os.path.exists(archive_dir):
 if logger is not None:
 logger.info("creating %s", archive_dir)
 if not dry_run:
 os.makedirs(archive_dir)

 # creating the tarball
 if logger is not None:
 logger.info('Creating tar archive')

 uid = _get_uid(owner)
 gid = _get_gid(group)

 def _set_uid_gid(tarinfo):
 if gid is not None:
 tarinfo.gid = gid
 tarinfo.gname = group
 if uid is not None:
 tarinfo.uid = uid
 tarinfo.uname = owner
 return tarinfo

 if not dry_run:
 tar = tarfile.open(archive_name, 'w|%s' % tar_compression)
 try:
 tar.add(base_dir, filter=_set_uid_gid)
 finally:
 tar.close()

 return archive_name

def _make_zipfile(base_name, base_dir, verbose=0, dry_run=0, logger=None):
 """Create a zip file from all the files under 'base_dir'.

 The output zip file will be named 'base_name' + ".zip". Returns the
 name of the output zip file.
 """
 import zipfile # late import for breaking circular dependency

 zip_filename = base_name + ".zip"
 archive_dir = os.path.dirname(base_name)

 if archive_dir and not os.path.exists(archive_dir):
 if logger is not None:
 logger.info("creating %s", archive_dir)
 if not dry_run:
 os.makedirs(archive_dir)

 if logger is not None:
 logger.info("creating '%s' and adding '%s' to it",
 zip_filename, base_dir)

 if not dry_run:
 with zipfile.ZipFile(zip_filename, "w",
 compression=zipfile.ZIP_DEFLATED) as zf:
 path = os.path.normpath(base_dir)
 if path != os.curdir:
 zf.write(path, path)
 if logger is not None:
 logger.info("adding '%s'", path)
 for dirpath, dirnames, filenames in os.walk(base_dir):
 for name in sorted(dirnames):
 path = os.path.normpath(os.path.join(dirpath, name))
 zf.write(path, path)
 if logger is not None:
 logger.info("adding '%s'", path)
 for name in filenames:
 path = os.path.normpath(os.path.join(dirpath, name))
 if os.path.isfile(path):
 zf.write(path, path)
 if logger is not None:
 logger.info("adding '%s'", path)

 return zip_filename

_ARCHIVE_FORMATS = {
 'tar': (_make_tarball, [('compress', None)], "uncompressed tar file"),
}

if _ZLIB_SUPPORTED:
 _ARCHIVE_FORMATS['gztar'] = (_make_tarball, [('compress', 'gzip')],
 "gzip'ed tar-file")
 _ARCHIVE_FORMATS['zip'] = (_make_zipfile, [], "ZIP file")

if _BZ2_SUPPORTED:
 _ARCHIVE_FORMATS['bztar'] = (_make_tarball, [('compress', 'bzip2')],
 "bzip2'ed tar-file")

if _LZMA_SUPPORTED:
 _ARCHIVE_FORMATS['xztar'] = (_make_tarball, [('compress', 'xz')],
 "xz'ed tar-file")

def get_archive_formats():
 """Returns a list of supported formats for archiving and unarchiving.

 Each element of the returned sequence is a tuple (name, description)
 """
 formats = [(name, registry[2]) for name, registry in
 _ARCHIVE_FORMATS.items()]
 formats.sort()
 return formats

def register_archive_format(name, function, extra_args=None, description=''):
 """Registers an archive format.

 name is the name of the format. function is the callable that will be
 used to create archives. If provided, extra_args is a sequence of
 (name, value) tuples that will be passed as arguments to the callable.
 description can be provided to describe the format, and will be returned
 by the get_archive_formats() function.
 """
 if extra_args is None:
 extra_args = []
 if not callable(function):
 raise TypeError('The %s object is not callable' % function)
 if not isinstance(extra_args, (tuple, list)):
 raise TypeError('extra_args needs to be a sequence')
 for element in extra_args:
 if not isinstance(element, (tuple, list)) or len(element) !=2:
 raise TypeError('extra_args elements are : (arg_name, value)')

 _ARCHIVE_FORMATS[name] = (function, extra_args, description)

def unregister_archive_format(name):
 del _ARCHIVE_FORMATS[name]

def make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,
 dry_run=0, owner=None, group=None, logger=None):
 """Create an archive file (eg. zip or tar).

 'base_name' is the name of the file to create, minus any format-specific
 extension; 'format' is the archive format: one of "zip", "tar", "gztar",
 "bztar", or "xztar". Or any other registered format.

 'root_dir' is a directory that will be the root directory of the
 archive; ie. we typically chdir into 'root_dir' before creating the
 archive. 'base_dir' is the directory where we start archiving from;
 ie. 'base_dir' will be the common prefix of all files and
 directories in the archive. 'root_dir' and 'base_dir' both default
 to the current directory. Returns the name of the archive file.

 'owner' and 'group' are used when creating a tar archive. By default,
 uses the current owner and group.
 """
 sys.audit("shutil.make_archive", base_name, format, root_dir, base_dir)
 save_cwd = os.getcwd()
 if root_dir is not None:
 if logger is not None:
 logger.debug("changing into '%s'", root_dir)
 base_name = os.path.abspath(base_name)
 if not dry_run:
 os.chdir(root_dir)

 if base_dir is None:
 base_dir = os.curdir

 kwargs = {'dry_run': dry_run, 'logger': logger}

 try:
 format_info = _ARCHIVE_FORMATS[format]
 except KeyError:
 raise ValueError("unknown archive format '%s'" % format) from None

 func = format_info[0]
 for arg, val in format_info[1]:
 kwargs[arg] = val

 if format != 'zip':
 kwargs['owner'] = owner
 kwargs['group'] = group

 try:
 filename = func(base_name, base_dir, **kwargs)
 finally:
 if root_dir is not None:
 if logger is not None:
 logger.debug("changing back to '%s'", save_cwd)
 os.chdir(save_cwd)

 return filename


def get_unpack_formats():
 """Returns a list of supported formats for unpacking.

 Each element of the returned sequence is a tuple
 (name, extensions, description)
 """
 formats = [(name, info[0], info[3]) for name, info in
 _UNPACK_FORMATS.items()]
 formats.sort()
 return formats

def _check_unpack_options(extensions, function, extra_args):
 """Checks what gets registered as an unpacker."""
 # first make sure no other unpacker is registered for this extension
 existing_extensions = {}
 for name, info in _UNPACK_FORMATS.items():
 for ext in info[0]:
 existing_extensions[ext] = name

 for extension in extensions:
 if extension in existing_extensions:
 msg = '%s is already registered for "%s"'
 raise RegistryError(msg % (extension,
 existing_extensions[extension]))

 if not callable(function):
 raise TypeError('The registered function must be a callable')


def register_unpack_format(name, extensions, function, extra_args=None,
 description=''):
 """Registers an unpack format.

 `name` is the name of the format. `extensions` is a list of extensions
 corresponding to the format.

 `function` is the callable that will be
 used to unpack archives. The callable will receive archives to unpack.
 If it's unable to handle an archive, it needs to raise a ReadError
 exception.

 If provided, `extra_args` is a sequence of
 (name, value) tuples that will be passed as arguments to the callable.
 description can be provided to describe the format, and will be returned
 by the get_unpack_formats() function.
 """
 if extra_args is None:
 extra_args = []
 _check_unpack_options(extensions, function, extra_args)
 _UNPACK_FORMATS[name] = extensions, function, extra_args, description

def unregister_unpack_format(name):
 """Removes the pack format from the registry."""
 del _UNPACK_FORMATS[name]

def _ensure_directory(path):
 """Ensure that the parent directory of `path` exists"""
 dirname = os.path.dirname(path)
 if not os.path.isdir(dirname):
 os.makedirs(dirname)

def _unpack_zipfile(filename, extract_dir):
 """Unpack zip `filename` to `extract_dir`
 """
 import zipfile # late import for breaking circular dependency

 if not zipfile.is_zipfile(filename):
 raise ReadError("%s is not a zip file" % filename)

 zip = zipfile.ZipFile(filename)
 try:
 for info in zip.infolist():
 name = info.filename

 # don't extract absolute paths or ones with .. in them
 if name.startswith('/') or '..' in name:
 continue

 target = os.path.join(extract_dir, *name.split('/'))
 if not target:
 continue

 _ensure_directory(target)
 if not name.endswith('/'):
 # file
 data = zip.read(info.filename)
 f = open(target, 'wb')
 try:
 f.write(data)
 finally:
 f.close()
 del data
 finally:
 zip.close()

def _unpack_tarfile(filename, extract_dir):
 """Unpack tar/tar.gz/tar.bz2/tar.xz `filename` to `extract_dir`
 """
 import tarfile # late import for breaking circular dependency
 try:
 tarobj = tarfile.open(filename)
 except tarfile.TarError:
 raise ReadError(
 "%s is not a compressed or uncompressed tar file" % filename)
 try:
 tarobj.extractall(extract_dir)
 finally:
 tarobj.close()

_UNPACK_FORMATS = {
 'tar': (['.tar'], _unpack_tarfile, [], "uncompressed tar file"),
 'zip': (['.zip'], _unpack_zipfile, [], "ZIP file"),
}

if _ZLIB_SUPPORTED:
 _UNPACK_FORMATS['gztar'] = (['.tar.gz', '.tgz'], _unpack_tarfile, [],
 "gzip'ed tar-file")

if _BZ2_SUPPORTED:
 _UNPACK_FORMATS['bztar'] = (['.tar.bz2', '.tbz2'], _unpack_tarfile, [],
 "bzip2'ed tar-file")

if _LZMA_SUPPORTED:
 _UNPACK_FORMATS['xztar'] = (['.tar.xz', '.txz'], _unpack_tarfile, [],
 "xz'ed tar-file")

def _find_unpack_format(filename):
 for name, info in _UNPACK_FORMATS.items():
 for extension in info[0]:
 if filename.endswith(extension):
 return name
 return None

def unpack_archive(filename, extract_dir=None, format=None):
 """Unpack an archive.

 `filename` is the name of the archive.

 `extract_dir` is the name of the target directory, where the archive
 is unpacked. If not provided, the current working directory is used.

 `format` is the archive format: one of "zip", "tar", "gztar", "bztar",
 or "xztar". Or any other registered format. If not provided,
 unpack_archive will use the filename extension and see if an unpacker
 was registered for that extension.

 In case none is found, a ValueError is raised.
 """
 sys.audit("shutil.unpack_archive", filename, extract_dir, format)

 if extract_dir is None:
 extract_dir = os.getcwd()

 extract_dir = os.fspath(extract_dir)
 filename = os.fspath(filename)

 if format is not None:
 try:
 format_info = _UNPACK_FORMATS[format]
 except KeyError:
 raise ValueError("Unknown unpack format '{0}'".format(format)) from None

 func = format_info[1]
 func(filename, extract_dir, **dict(format_info[2]))
 else:
 # we need to look at the registered unpackers supported extensions
 format = _find_unpack_format(filename)
 if format is None:
 raise ReadError("Unknown archive format '{0}'".format(filename))

 func = _UNPACK_FORMATS[format][1]
 kwargs = dict(_UNPACK_FORMATS[format][2])
 func(filename, extract_dir, **kwargs)


if hasattr(os, 'statvfs'):

 __all__.append('disk_usage')
 _ntuple_diskusage = collections.namedtuple('usage', 'total used free')
 _ntuple_diskusage.total.__doc__ = 'Total space in bytes'
 _ntuple_diskusage.used.__doc__ = 'Used space in bytes'
 _ntuple_diskusage.free.__doc__ = 'Free space in bytes'

 def disk_usage(path):
 """Return disk usage statistics about the given path.

 Returned value is a named tuple with attributes 'total', 'used' and
 'free', which are the amount of total, used and free space, in bytes.
 """
 st = os.statvfs(path)
 free = st.f_bavail * st.f_frsize
 total = st.f_blocks * st.f_frsize
 used = (st.f_blocks - st.f_bfree) * st.f_frsize
 return _ntuple_diskusage(total, used, free)

elif _WINDOWS:

 __all__.append('disk_usage')
 _ntuple_diskusage = collections.namedtuple('usage', 'total used free')

 def disk_usage(path):
 """Return disk usage statistics about the given path.

 Returned values is a named tuple with attributes 'total', 'used' and
 'free', which are the amount of total, used and free space, in bytes.
 """
 total, free = nt._getdiskusage(path)
 used = total - free
 return _ntuple_diskusage(total, used, free)


def chown(path, user=None, group=None):
 """Change owner user and group of the given path.

 user and group can be the uid/gid or the user/group names, and in that case,
 they are converted to their respective uid/gid.
 """
 sys.audit('shutil.chown', path, user, group)

 if user is None and group is None:
 raise ValueError("user and/or group must be set")

 _user = user
 _group = group

 # -1 means don't change it
 if user is None:
 _user = -1
 # user can either be an int (the uid) or a string (the system username)
 elif isinstance(user, str):
 _user = _get_uid(user)
 if _user is None:
 raise LookupError("no such user: {!r}".format(user))

 if group is None:
 _group = -1
 elif not isinstance(group, int):
 _group = _get_gid(group)
 if _group is None:
 raise LookupError("no such group: {!r}".format(group))

 os.chown(path, _user, _group)

def get_terminal_size(fallback=(80, 24)):
 """Get the size of the terminal window.

 For each of the two dimensions, the environment variable, COLUMNS
 and LINES respectively, is checked. If the variable is defined and
 the value is a positive integer, it is used.

 When COLUMNS or LINES is not defined, which is the common case,
 the terminal connected to sys.__stdout__ is queried
 by invoking os.get_terminal_size.

 If the terminal size cannot be successfully queried, either because
 the system doesn't support querying, or because we are not
 connected to a terminal, the value given in fallback parameter
 is used. Fallback defaults to (80, 24) which is the default
 size used by many terminal emulators.

 The value returned is a named tuple of type os.terminal_size.
 """
 # columns, lines are the working values
 try:
 columns = int(os.environ['COLUMNS'])
 except (KeyError, ValueError):
 columns = 0

 try:
 lines = int(os.environ['LINES'])
 except (KeyError, ValueError):
 lines = 0

 # only query if necessary
 if columns <= 0 or lines <= 0:
 try:
 size = os.get_terminal_size(sys.__stdout__.fileno())
 except (AttributeError, ValueError, OSError):
 # stdout is None, closed, detached, or not a terminal, or
 # os.get_terminal_size() is unsupported
 size = os.terminal_size(fallback)
 if columns <= 0:
 columns = size.columns
 if lines <= 0:
 lines = size.lines

 return os.terminal_size((columns, lines))


# Check that a given file can be accessed with the correct mode.
# Additionally check that `file` is not a directory, as on Windows
# directories pass the os.access check.
def _access_check(fn, mode):
 return (os.path.exists(fn) and os.access(fn, mode)
 and not os.path.isdir(fn))


def which(cmd, mode=os.F_OK | os.X_OK, path=None):
 """Given a command, mode, and a PATH string, return the path which
 conforms to the given mode on the PATH, or None if there is no such
 file.

 `mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
 of os.environ.get("PATH"), or can be overridden with a custom search
 path.

 """
 # If we're given a path with a directory part, look it up directly rather
 # than referring to PATH directories. This includes checking relative to the
 # current directory, e.g. ./script
 if os.path.dirname(cmd):
 if _access_check(cmd, mode):
 return cmd
 return None

 use_bytes = isinstance(cmd, bytes)

 if path is None:
 path = os.environ.get("PATH", None)
 if path is None:
 try:
 path = os.confstr("CS_PATH")
 except (AttributeError, ValueError):
 # os.confstr() or CS_PATH is not available
 path = os.defpath
 # bpo-35755: Don't use os.defpath if the PATH environment variable is
 # set to an empty string

 # PATH='' doesn't match, whereas PATH=':' looks in the current directory
 if not path:
 return None

 if use_bytes:
 path = os.fsencode(path)
 path = path.split(os.fsencode(os.pathsep))
 else:
 path = os.fsdecode(path)
 path = path.split(os.pathsep)

 if sys.platform == "win32":
 # The current directory takes precedence on Windows.
 curdir = os.curdir
 if use_bytes:
 curdir = os.fsencode(curdir)
 if curdir not in path:
 path.insert(0, curdir)

 # PATHEXT is necessary to check on Windows.
 pathext_source = os.getenv("PATHEXT") or _WIN_DEFAULT_PATHEXT
 pathext = [ext for ext in pathext_source.split(os.pathsep) if ext]

 if use_bytes:
 pathext = [os.fsencode(ext) for ext in pathext]
 # See if the given file matches any of the expected path extensions.
 # This will allow us to short circuit when given "python.exe".
 # If it does match, only test that one, otherwise we have to try
 # others.
 if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
 files = [cmd]
 else:
 files = [cmd + ext for ext in pathext]
 else:
 # On other platforms you don't have things like PATHEXT to tell you
 # what file suffixes are executable, so just pass on cmd as-is.
 files = [cmd]

 seen = set()
 for dir in path:
 normdir = os.path.normcase(dir)
 if not normdir in seen:
 seen.add(normdir)
 for thefile in files:
 name = os.path.join(dir, thefile)
 if _access_check(name, mode):
 return name
 return None