easy_install.py

"""
Easy Install
------------

A tool for doing automatic download/extract/build of distutils-based Python
packages.  For detailed documentation, see the accompanying EasyInstall.txt
file, or visit the `EasyInstall home page`__.

__ https://setuptools.readthedocs.io/en/latest/easy_install.html

"""

from glob import glob
from distutils.util import get_platform
from distutils.util import convert_path, subst_vars
from distutils.errors import (
    DistutilsArgError, DistutilsOptionError,
    DistutilsError, DistutilsPlatformError,
)
from distutils.command.install import INSTALL_SCHEMES, SCHEME_KEYS
from distutils import log, dir_util
from distutils.command.build_scripts import first_line_re
from distutils.spawn import find_executable
import sys
import os
import zipimport
import shutil
import tempfile
import zipfile
import re
import stat
import random
import textwrap
import warnings
import site
import struct
import contextlib
import subprocess
import shlex
import io
import configparser


from sysconfig import get_config_vars, get_path

from setuptools import SetuptoolsDeprecationWarning

from setuptools import Command
from setuptools.sandbox import run_setup
from setuptools.command import setopt
from setuptools.archive_util import unpack_archive
from setuptools.package_index import (
    PackageIndex, parse_requirement_arg, URL_SCHEME,
)
from setuptools.command import bdist_egg, egg_info
from setuptools.wheel import Wheel
from pkg_resources import (
    yield_lines, normalize_path, resource_string, ensure_directory,
    get_distribution, find_distributions, Environment, Requirement,
    Distribution, PathMetadata, EggMetadata, WorkingSet, DistributionNotFound,
    VersionConflict, DEVELOP_DIST,
)
import pkg_resources

# Turn on PEP440Warnings
warnings.filterwarnings("default", category=pkg_resources.PEP440Warning)

__all__ = [
    'samefile', 'easy_install', 'PthDistributions', 'extract_wininst_cfg',
    'main', 'get_exe_prefixes',
]


def is_64bit():
    return struct.calcsize("P") == 8


def samefile(p1, p2):
    """
    Determine if two paths reference the same file.

    Augments os.path.samefile to work on Windows and
    suppresses errors if the path doesn't exist.
    """
    both_exist = os.path.exists(p1) and os.path.exists(p2)
    use_samefile = hasattr(os.path, 'samefile') and both_exist
    if use_samefile:
        return os.path.samefile(p1, p2)
    norm_p1 = os.path.normpath(os.path.normcase(p1))
    norm_p2 = os.path.normpath(os.path.normcase(p2))
    return norm_p1 == norm_p2


def _to_bytes(s):
    return s.encode('utf8')


def isascii(s):
    try:
        s.encode('ascii')
        return True
    except UnicodeError:
        return False


def _one_liner(text):
    return textwrap.dedent(text).strip().replace('\n', '; ')


class easy_install(Command):
    """Manage a download/build/install process"""
    description = "Find/get/install Python packages"
    command_consumes_arguments = True

    user_options = [
        ('prefix=', None, "installation prefix"),
        ("zip-ok", "z", "install package as a zipfile"),
        ("multi-version", "m", "make apps have to require() a version"),
        ("upgrade", "U", "force upgrade (searches PyPI for latest versions)"),
        ("install-dir=", "d", "install package to DIR"),
        ("script-dir=", "s", "install scripts to DIR"),
        ("exclude-scripts", "x", "Don't install scripts"),
        ("always-copy", "a", "Copy all needed packages to install dir"),
        ("index-url=", "i", "base URL of Python Package Index"),
        ("find-links=", "f", "additional URL(s) to search for packages"),
        ("build-directory=", "b",
         "download/extract/build in DIR; keep the results"),
        ('optimize=', 'O',
         "also compile with optimization: -O1 for \"python -O\", "
         "-O2 for \"python -OO\", and -O0 to disable [default: -O0]"),
        ('record=', None,
         "filename in which to record list of installed files"),
        ('always-unzip', 'Z', "don't install as a zipfile, no matter what"),
        ('site-dirs=', 'S', "list of directories where .pth files work"),
        ('editable', 'e', "Install specified packages in editable form"),
        ('no-deps', 'N', "don't install dependencies"),
        ('allow-hosts=', 'H', "pattern(s) that hostnames must match"),
        ('local-snapshots-ok', 'l',
         "allow building eggs from local checkouts"),
        ('version', None, "print version information and exit"),
        ('no-find-links', None,
         "Don't load find-links defined in packages being installed"),
        ('user', None, "install in user site-package '%s'" % site.USER_SITE)
    ]
    boolean_options = [
        'zip-ok', 'multi-version', 'exclude-scripts', 'upgrade', 'always-copy',
        'editable',
        'no-deps', 'local-snapshots-ok', 'version',
        'user'
    ]

    negative_opt = {'always-unzip': 'zip-ok'}
    create_index = PackageIndex

    def initialize_options(self):
        # the --user option seems to be an opt-in one,
        # so the default should be False.
        self.user = 0
        self.zip_ok = self.local_snapshots_ok = None
        self.install_dir = self.script_dir = self.exclude_scripts = None
        self.index_url = None
        self.find_links = None
        self.build_directory = None
        self.args = None
        self.optimize = self.record = None
        self.upgrade = self.always_copy = self.multi_version = None
        self.editable = self.no_deps = self.allow_hosts = None
        self.root = self.prefix = self.no_report = None
        self.version = None
        self.install_purelib = None  # for pure module distributions
        self.install_platlib = None  # non-pure (dists w/ extensions)
        self.install_headers = None  # for C/C++ headers
        self.install_lib = None  # set to either purelib or platlib
        self.install_scripts = None
        self.install_data = None
        self.install_base = None
        self.install_platbase = None
        if site.ENABLE_USER_SITE:
            self.install_userbase = site.USER_BASE
            self.install_usersite = site.USER_SITE
        else:
            self.install_userbase = None
            self.install_usersite = None
        self.no_find_links = None

        # Options not specifiable via command line
        self.package_index = None
        self.pth_file = self.always_copy_from = None
        self.site_dirs = None
        self.installed_projects = {}
        # Always read easy_install options, even if we are subclassed, or have
        # an independent instance created.  This ensures that defaults will
        # always come from the standard configuration file(s)' "easy_install"
        # section, even if this is a "develop" or "install" command, or some
        # other embedding.
        self._dry_run = None
        self.verbose = self.distribution.verbose
        self.distribution._set_command_options(
            self, self.distribution.get_option_dict('easy_install')
        )

    def delete_blockers(self, blockers):
        extant_blockers = (
            filename for filename in blockers
            if os.path.exists(filename) or os.path.islink(filename)
        )
        list(map(self._delete_path, extant_blockers))

    def _delete_path(self, path):
        log.info("Deleting %s", path)
        if self.dry_run:
            return

        is_tree = os.path.isdir(path) and not os.path.islink(path)
        remover = rmtree if is_tree else os.unlink
        remover(path)

    @staticmethod
    def _render_version():
        """
        Render the Setuptools version and installation details, then exit.
        """
        ver = '{}.{}'.format(*sys.version_info)
        dist = get_distribution('setuptools')
        tmpl = 'setuptools {dist.version} from {dist.location} (Python {ver})'
        print(tmpl.format(**locals()))
        raise SystemExit()

    def finalize_options(self):  # noqa: C901  # is too complex (25)  # FIXME
        self.version and self._render_version()

        py_version = sys.version.split()[0]
        prefix, exec_prefix = get_config_vars('prefix', 'exec_prefix')

        self.config_vars = {
            'dist_name': self.distribution.get_name(),
            'dist_version': self.distribution.get_version(),
            'dist_fullname': self.distribution.get_fullname(),
            'py_version': py_version,
            'py_version_short': py_version[0:3],
            'py_version_nodot': py_version[0] + py_version[2],
            'sys_prefix': prefix,
            'prefix': prefix,
            'sys_exec_prefix': exec_prefix,
            'exec_prefix': exec_prefix,
            # Only python 3.2+ has abiflags
            'abiflags': getattr(sys, 'abiflags', ''),
        }

        if site.ENABLE_USER_SITE:
            self.config_vars['userbase'] = self.install_userbase
            self.config_vars['usersite'] = self.install_usersite

        elif self.user:
            log.warn("WARNING: The user site-packages directory is disabled.")

        self._fix_install_dir_for_user_site()

        self.expand_basedirs()
        self.expand_dirs()

        self._expand(
            'install_dir', 'script_dir', 'build_directory',
            'site_dirs',
        )
        # If a non-default installation directory was specified, default the
        # script directory to match it.
        if self.script_dir is None:
            self.script_dir = self.install_dir

        if self.no_find_links is None:
            self.no_find_links = False

        # Let install_dir get set by install_lib command, which in turn
        # gets its info from the install command, and takes into account
        # --prefix and --home and all that other crud.
        self.set_undefined_options(
            'install_lib', ('install_dir', 'install_dir')
        )
        # Likewise, set default script_dir from 'install_scripts.install_dir'
        self.set_undefined_options(
            'install_scripts', ('install_dir', 'script_dir')
        )

        if self.user and self.install_purelib:
            self.install_dir = self.install_purelib
            self.script_dir = self.install_scripts
        # default --record from the install command
        self.set_undefined_options('install', ('record', 'record'))
        # Should this be moved to the if statement below? It's not used
        # elsewhere
        normpath = map(normalize_path, sys.path)
        self.all_site_dirs = get_site_dirs()
        if self.site_dirs is not None:
            site_dirs = [
                os.path.expanduser(s.strip()) for s in
                self.site_dirs.split(',')
            ]
            for d in site_dirs:
                if not os.path.isdir(d):
                    log.warn("%s (in --site-dirs) does not exist", d)
                elif normalize_path(d) not in normpath:
                    raise DistutilsOptionError(
                        d + " (in --site-dirs) is not on sys.path"
                    )
                else:
                    self.all_site_dirs.append(normalize_path(d))
        if not self.editable:
            self.check_site_dir()
        self.index_url = self.index_url or "https://pypi.org/simple/"
        self.shadow_path = self.all_site_dirs[:]
        for path_item in self.install_dir, normalize_path(self.script_dir):
            if path_item not in self.shadow_path:
                self.shadow_path.insert(0, path_item)

        if self.allow_hosts is not None:
            hosts = [s.strip() for s in self.allow_hosts.split(',')]
        else:
            hosts = ['*']
        if self.package_index is None:
            self.package_index = self.create_index(
                self.index_url, search_path=self.shadow_path, hosts=hosts,
            )
        self.local_index = Environment(self.shadow_path + sys.path)

        if self.find_links is not None:
            if isinstance(self.find_links, str):
                self.find_links = self.find_links.split()
        else:
            self.find_links = []
        if self.local_snapshots_ok:
            self.package_index.scan_egg_links(self.shadow_path + sys.path)
        if not self.no_find_links:
            self.package_index.add_find_links(self.find_links)
        self.set_undefined_options('install_lib', ('optimize', 'optimize'))
        if not isinstance(self.optimize, int):
            try:
                self.optimize = int(self.optimize)
                if not (0 <= self.optimize <= 2):
                    raise ValueError
            except ValueError as e:
                raise DistutilsOptionError(
                    "--optimize must be 0, 1, or 2"
                ) from e

        if self.editable and not self.build_directory:
            raise DistutilsArgError(
                "Must specify a build directory (-b) when using --editable"
            )
        if not self.args:
            raise DistutilsArgError(
                "No urls, filenames, or requirements specified (see --help)")

        self.outputs = []

    def _fix_install_dir_for_user_site(self):
        """
        Fix the install_dir if "--user" was used.
        """
        if not self.user or not site.ENABLE_USER_SITE:
            return

        self.create_home_path()
        if self.install_userbase is None:
            msg = "User base directory is not specified"
            raise DistutilsPlatformError(msg)
        self.install_base = self.install_platbase = self.install_userbase
        scheme_name = os.name.replace('posix', 'unix') + '_user'
        self.select_scheme(scheme_name)

    def _expand_attrs(self, attrs):
        for attr in attrs:
            val = getattr(self, attr)
            if val is not None:
                if os.name == 'posix' or os.name == 'nt':
                    val = os.path.expanduser(val)
                val = subst_vars(val, self.config_vars)
                setattr(self, attr, val)

    def expand_basedirs(self):
        """Calls `os.path.expanduser` on install_base, install_platbase and
        root."""
        self._expand_attrs(['install_base', 'install_platbase', 'root'])

    def expand_dirs(self):
        """Calls `os.path.expanduser` on install dirs."""
        dirs = [
            'install_purelib',
            'install_platlib',
            'install_lib',
            'install_headers',
            'install_scripts',
            'install_data',
        ]
        self._expand_attrs(dirs)

    def run(self, show_deprecation=True):
        if show_deprecation:
            self.announce(
                "WARNING: The easy_install command is deprecated "
                "and will be removed in a future version.",
                log.WARN,
            )
        if self.verbose != self.distribution.verbose:
            log.set_verbosity(self.verbose)
        try:
            for spec in self.args:
                self.easy_install(spec, not self.no_deps)
            if self.record:
                outputs = self.outputs
                if self.root:  # strip any package prefix
                    root_len = len(self.root)
                    for counter in range(len(outputs)):
                        outputs[counter] = outputs[counter][root_len:]
                from distutils import file_util

                self.execute(
                    file_util.write_file, (self.record, outputs),
                    "writing list of installed files to '%s'" %
                    self.record
                )
            self.warn_deprecated_options()
        finally:
            log.set_verbosity(self.distribution.verbose)

    def pseudo_tempname(self):
        """Return a pseudo-tempname base in the install directory.
        This code is intentionally naive; if a malicious party can write to
        the target directory you're already in deep doodoo.
        """
        try:
            pid = os.getpid()
        except Exception:
            pid = random.randint(0, sys.maxsize)
        return os.path.join(self.install_dir, "test-easy-install-%s" % pid)

    def warn_deprecated_options(self):
        pass

    def check_site_dir(self):  # noqa: C901  # is too complex (12)  # FIXME
        """Verify that self.install_dir is .pth-capable dir, if needed"""

        instdir = normalize_path(self.install_dir)
        pth_file = os.path.join(instdir, 'easy-install.pth')

        if not os.path.exists(instdir):
            try:
                os.makedirs(instdir)
            except (OSError, IOError):
                self.cant_write_to_target()

        # Is it a configured, PYTHONPATH, implicit, or explicit site dir?
        is_site_dir = instdir in self.all_site_dirs

        if not is_site_dir and not self.multi_version:
            # No?  Then directly test whether it does .pth file processing
            is_site_dir = self.check_pth_processing()
        else:
            # make sure we can write to target dir
            testfile = self.pseudo_tempname() + '.write-test'
            test_exists = os.path.exists(testfile)
            try:
                if test_exists:
                    os.unlink(testfile)
                open(testfile, 'w').close()
                os.unlink(testfile)
            except (OSError, IOError):
                self.cant_write_to_target()

        if not is_site_dir and not self.multi_version:
            # Can't install non-multi to non-site dir with easy_install
            pythonpath = os.environ.get('PYTHONPATH', '')
            log.warn(self.__no_default_msg, self.install_dir, pythonpath)

        if is_site_dir:
            if self.pth_file is None:
                self.pth_file = PthDistributions(pth_file, self.all_site_dirs)
        else:
            self.pth_file = None

        if self.multi_version and not os.path.exists(pth_file):
            self.pth_file = None  # don't create a .pth file
        self.install_dir = instdir

    __cant_write_msg = textwrap.dedent("""
        can't create or remove files in install directory

        The following error occurred while trying to add or remove files in the
        installation directory:

            %s

        The installation directory you specified (via --install-dir, --prefix, or
        the distutils default setting) was:

            %s
        """).lstrip()  # noqa

    __not_exists_id = textwrap.dedent("""
        This directory does not currently exist.  Please create it and try again, or
        choose a different installation directory (using the -d or --install-dir
        option).
        """).lstrip()  # noqa

    __access_msg = textwrap.dedent("""
        Perhaps your account does not have write access to this directory?  If the
        installation directory is a system-owned directory, you may need to sign in
        as the administrator or "root" account.  If you do not have administrative
        access to this machine, you may wish to choose a different installation
        directory, preferably one that is listed in your PYTHONPATH environment
        variable.

        For information on other options, you may wish to consult the
        documentation at:

          https://setuptools.readthedocs.io/en/latest/easy_install.html

        Please make the appropriate changes for your system and try again.
        """).lstrip()  # noqa

    def cant_write_to_target(self):
        msg = self.__cant_write_msg % (sys.exc_info()[1], self.install_dir,)

        if not os.path.exists(self.install_dir):
            msg += '\n' + self.__not_exists_id
        else:
            msg += '\n' + self.__access_msg
        raise DistutilsError(msg)

    def check_pth_processing(self):
        """Empirically verify whether .pth files are supported in inst. dir"""
        instdir = self.install_dir
        log.info("Checking .pth file support in %s", instdir)
        pth_file = self.pseudo_tempname() + ".pth"
        ok_file = pth_file + '.ok'
        ok_exists = os.path.exists(ok_file)
        tmpl = _one_liner("""
            import os
            f = open({ok_file!r}, 'w')
            f.write('OK')
            f.close()
            """) + '\n'
        try:
            if ok_exists:
                os.unlink(ok_file)
            dirname = os.path.dirname(ok_file)
            os.makedirs(dirname, exist_ok=True)
            f = open(pth_file, 'w')
        except (OSError, IOError):
            self.cant_write_to_target()
        else:
            try:
                f.write(tmpl.format(**locals()))
                f.close()
                f = None
                executable = sys.executable
                if os.name == 'nt':
                    dirname, basename = os.path.split(executable)
                    alt = os.path.join(dirname, 'pythonw.exe')
                    use_alt = (
                        basename.lower() == 'python.exe' and
                        os.path.exists(alt)
                    )
                    if use_alt:
                        # use pythonw.exe to avoid opening a console window
                        executable = alt

                from distutils.spawn import spawn

                spawn([executable, '-E', '-c', 'pass'], 0)

                if os.path.exists(ok_file):
                    log.info(
                        "TEST PASSED: %s appears to support .pth files",
                        instdir
                    )
                    return True
            finally:
                if f:
                    f.close()
                if os.path.exists(ok_file):
                    os.unlink(ok_file)
                if os.path.exists(pth_file):
                    os.unlink(pth_file)
        if not self.multi_version:
            log.warn("TEST FAILED: %s does NOT support .pth files", instdir)
        return False

    def install_egg_scripts(self, dist):
        """Write all the scripts for `dist`, unless scripts are excluded"""
        if not self.exclude_scripts and dist.metadata_isdir('scripts'):
            for script_name in dist.metadata_listdir('scripts'):
                if dist.metadata_isdir('scripts/' + script_name):
                    # The "script" is a directory, likely a Python 3
                    # __pycache__ directory, so skip it.
                    continue
                self.install_script(
                    dist, script_name,
                    dist.get_metadata('scripts/' + script_name)
                )
        self.install_wrapper_scripts(dist)

    def add_output(self, path):
        if os.path.isdir(path):
            for base, dirs, files in os.walk(path):
                for filename in files:
                    self.outputs.append(os.path.join(base, filename))
        else:
            self.outputs.append(path)

    def not_editable(self, spec):
        if self.editable:
            raise DistutilsArgError(
                "Invalid argument %r: you can't use filenames or URLs "
                "with --editable (except via the --find-links option)."
                % (spec,)
            )

    def check_editable(self, spec):
        if not self.editable:
            return

        if os.path.exists(os.path.join(self.build_directory, spec.key)):
            raise DistutilsArgError(
                "%r already exists in %s; can't do a checkout there" %
                (spec.key, self.build_directory)
            )

    @contextlib.contextmanager
    def _tmpdir(self):
        tmpdir = tempfile.mkdtemp(prefix=u"easy_install-")
        try:
            # cast to str as workaround for #709 and #710 and #712
            yield str(tmpdir)
        finally:
            os.path.exists(tmpdir) and rmtree(tmpdir)

    def easy_install(self, spec, deps=False):
        with self._tmpdir() as tmpdir:
            if not isinstance(spec, Requirement):
                if URL_SCHEME(spec):
                    # It's a url, download it to tmpdir and process
                    self.not_editable(spec)
                    dl = self.package_index.download(spec, tmpdir)
                    return self.install_item(None, dl, tmpdir, deps, True)

                elif os.path.exists(spec):
                    # Existing file or directory, just process it directly
                    self.not_editable(spec)
                    return self.install_item(None, spec, tmpdir, deps, True)
                else:
                    spec = parse_requirement_arg(spec)

            self.check_editable(spec)
            dist = self.package_index.fetch_distribution(
                spec, tmpdir, self.upgrade, self.editable,
                not self.always_copy, self.local_index
            )
            if dist is None:
                msg = "Could not find suitable distribution for %r" % spec
                if self.always_copy:
                    msg += " (--always-copy skips system and development eggs)"
                raise DistutilsError(msg)
            elif dist.precedence == DEVELOP_DIST:
                # .egg-info dists don't need installing, just process deps
                self.process_distribution(spec, dist, deps, "Using")
                return dist
            else:
                return self.install_item(spec, dist.location, tmpdir, deps)

    def install_item(self, spec, download, tmpdir, deps, install_needed=False):

        # Installation is also needed if file in tmpdir or is not an egg
        install_needed = install_needed or self.always_copy
        install_needed = install_needed or os.path.dirname(download) == tmpdir
        install_needed = install_needed or not download.endswith('.egg')
        install_needed = install_needed or (
            self.always_copy_from is not None and
            os.path.dirname(normalize_path(download)) ==
            normalize_path(self.always_copy_from)
        )

        if spec and not install_needed:
            # at this point, we know it's a local .egg, we just don't know if
            # it's already installed.
            for dist in self.local_index[spec.project_name]:
                if dist.location == download:
                    break
            else:
                install_needed = True  # it's not in the local index

        log.info("Processing %s", os.path.basename(download))

        if install_needed:
            dists = self.install_eggs(spec, download, tmpdir)
            for dist in dists:
                self.process_distribution(spec, dist, deps)
        else:
            dists = [self.egg_distribution(download)]
            self.process_distribution(spec, dists[0], deps, "Using")

        if spec is not None:
            for dist in dists:
                if dist in spec:
                    return dist

    def select_scheme(self, name):
        """Sets the install directories by applying the install schemes."""
        # it's the caller's problem if they supply a bad name!
        scheme = INSTALL_SCHEMES[name]
        for key in SCHEME_KEYS:
            attrname = 'install_' + key
            if getattr(self, attrname) is None:
                setattr(self, attrname, scheme[key])

    # FIXME: 'easy_install.process_distribution' is too complex (12)
    def process_distribution(  # noqa: C901
            self, requirement, dist, deps=True, *info,
    ):
        self.update_pth(dist)
        self.package_index.add(dist)
        if dist in self.local_index[dist.key]:
            self.local_index.remove(dist)
        self.local_index.add(dist)
        self.install_egg_scripts(dist)
        self.installed_projects[dist.key] = dist
        log.info(self.installation_report(requirement, dist, *info))
        if (dist.has_metadata('dependency_links.txt') and
                not self.no_find_links):
            self.package_index.add_find_links(
                dist.get_metadata_lines('dependency_links.txt')
            )
        if not deps and not self.always_copy:
            return
        elif requirement is not None and dist.key != requirement.key:
            log.warn("Skipping dependencies for %s", dist)
            return  # XXX this is not the distribution we were looking for
        elif requirement is None or dist not in requirement:
            # if we wound up with a different version, resolve what we've got
            distreq = dist.as_requirement()
            requirement = Requirement(str(distreq))
        log.info("Processing dependencies for %s", requirement)
        try:
            distros = WorkingSet([]).resolve(
                [requirement], self.local_index, self.easy_install
            )
        except DistributionNotFound as e:
            raise DistutilsError(str(e)) from e
        except VersionConflict as e:
            raise DistutilsError(e.report()) from e
        if self.always_copy or self.always_copy_from:
            # Force all the relevant distros to be copied or activated
            for dist in distros:
                if dist.key not in self.installed_projects:
                    self.easy_install(dist.as_requirement())
        log.info("Finished processing dependencies for %s", requirement)

    def should_unzip(self, dist):
        if self.zip_ok is not None:
            return not self.zip_ok
        if dist.has_metadata('not-zip-safe'):
            return True
        if not dist.has_metadata('zip-safe'):
            return True
        return False

    def maybe_move(self, spec, dist_filename, setup_base):
        dst = os.path.join(self.build_directory, spec.key)
        if os.path.exists(dst):
            msg = (
                "%r already exists in %s; build directory %s will not be kept"
            )
            log.warn(msg, spec.key, self.build_directory, setup_base)
            return setup_base
        if os.path.isdir(dist_filename):
            setup_base = dist_filename
        else:
            if os.path.dirname(dist_filename) == setup_base:
                os.unlink(dist_filename)  # get it out of the tmp dir
            contents = os.listdir(setup_base)
            if len(contents) == 1:
                dist_filename = os.path.join(setup_base, contents[0])
                if os.path.isdir(dist_filename):
                    # if the only thing there is a directory, move it instead
                    setup_base = dist_filename
        ensure_directory(dst)
        shutil.move(setup_base, dst)
        return dst

    def install_wrapper_scripts(self, dist):
        if self.exclude_scripts:
            return
        for args in ScriptWriter.best().get_args(dist):
            self.write_script(*args)

    def install_script(self, dist, script_name, script_text, dev_path=None):
        """Generate a legacy script wrapper and install it"""
        spec = str(dist.as_requirement())
        is_script = is_python_script(script_text, script_name)

        if is_script:
            body = self._load_template(dev_path) % locals()
            script_text = ScriptWriter.get_header(script_text) + body
        self.write_script(script_name, _to_bytes(script_text), 'b')

    @staticmethod
    def _load_template(dev_path):
        """
        There are a couple of template scripts in the package. This
        function loads one of them and prepares it for use.
        """
        # See https://github.com/pypa/setuptools/issues/134 for info
        # on script file naming and downstream issues with SVR4
        name = 'script.tmpl'
        if dev_path:
            name = name.replace('.tmpl', ' (dev).tmpl')

        raw_bytes = resource_string('setuptools', name)
        return raw_bytes.decode('utf-8')

    def write_script(self, script_name, contents, mode="t", blockers=()):
        """Write an executable file to the scripts directory"""
        self.delete_blockers(  # clean up old .py/.pyw w/o a script
            [os.path.join(self.script_dir, x) for x in blockers]
        )
        log.info("Installing %s script to %s", script_name, self.script_dir)
        target = os.path.join(self.script_dir, script_name)
        self.add_output(target)

        if self.dry_run:
            return

        mask = current_umask()
        ensure_directory(target)
        if os.path.exists(target):
            os.unlink(target)
        with open(target, "w" + mode) as f:
            f.write(contents)
        chmod(target, 0o777 - mask)

    def install_eggs(self, spec, dist_filename, tmpdir):
        # .egg dirs or files are already built, so just return them
        installer_map = {
            '.egg': self.install_egg,
            '.exe': self.install_exe,
            '.whl': self.install_wheel,
        }
        try:
            install_dist = installer_map[
                dist_filename.lower()[-4:]
            ]
        except KeyError:
            pass
        else:
            return [install_dist(dist_filename, tmpdir)]

        # Anything else, try to extract and build
        setup_base = tmpdir
        if os.path.isfile(dist_filename) and not dist_filename.endswith('.py'):
            unpack_archive(dist_filename, tmpdir, self.unpack_progress)
        elif os.path.isdir(dist_filename):
            setup_base = os.path.abspath(dist_filename)

        if (setup_base.startswith(tmpdir)  # something we downloaded
                and self.build_directory and spec is not None):
            setup_base = self.maybe_move(spec, dist_filename, setup_base)

        # Find the setup.py file
        setup_script = os.path.join(setup_base, 'setup.py')

        if not os.path.exists(setup_script):
            setups = glob(os.path.join(setup_base, '*', 'setup.py'))
            if not setups:
                raise DistutilsError(
                    "Couldn't find a setup script in %s" %
                    os.path.abspath(dist_filename)
                )
            if len(setups) > 1:
                raise DistutilsError(
                    "Multiple setup scripts in %s" %
                    os.path.abspath(dist_filename)
                )
            setup_script = setups[0]

        # Now run it, and return the result
        if self.editable:
            log.info(self.report_editable(spec, setup_script))
            return []
        else:
            return self.build_and_install(setup_script, setup_base)

    def egg_distribution(self, egg_path):
        if os.path.isdir(egg_path):
            metadata = PathMetadata(egg_path, os.path.join(egg_path,
                                                           'EGG-INFO'))
        else:
            metadata = EggMetadata(zipimport.zipimporter(egg_path))
        return Distribution.from_filename(egg_path, metadata=metadata)

    # FIXME: 'easy_install.install_egg' is too complex (11)
    def install_egg(self, egg_path, tmpdir):  # noqa: C901
        destination = os.path.join(
            self.install_dir,
            os.path.basename(egg_path),
        )
        destination = os.path.abspath(destination)
        if not self.dry_run:
            ensure_directory(destination)

        dist = self.egg_distribution(egg_path)
        if not samefile(egg_path, destination):
            if os.path.isdir(destination) and not os.path.islink(destination):
                dir_util.remove_tree(destination, dry_run=self.dry_run)
            elif os.path.exists(destination):
                self.execute(
                    os.unlink,
                    (destination,),
                    "Removing " + destination,
                )
            try:
                new_dist_is_zipped = False
                if os.path.isdir(egg_path):
                    if egg_path.startswith(tmpdir):
                        f, m = shutil.move, "Moving"
                    else:
                        f, m = shutil.copytree, "Copying"
                elif self.should_unzip(dist):
                    self.mkpath(destination)
                    f, m = self.unpack_and_compile, "Extracting"
                else:
                    new_dist_is_zipped = True
                    if egg_path.startswith(tmpdir):
                        f, m = shutil.move, "Moving"
                    else:
                        f, m = shutil.copy2, "Copying"
                self.execute(
                    f,
                    (egg_path, destination),
                    (m + " %s to %s") % (
                        os.path.basename(egg_path),
                        os.path.dirname(destination)
                    ),
                )
                update_dist_caches(
                    destination,
                    fix_zipimporter_caches=new_dist_is_zipped,
                )
            except Exception:
                update_dist_caches(destination, fix_zipimporter_caches=False)
                raise

        self.add_output(destination)
        return self.egg_distribution(destination)

    def install_exe(self, dist_filename, tmpdir):
        # See if it's valid, get data
        cfg = extract_wininst_cfg(dist_filename)
        if cfg is None:
            raise DistutilsError(
                "%s is not a valid distutils Windows .exe" % dist_filename
            )
        # Create a dummy distribution object until we build the real distro
        dist = Distribution(
            None,
            project_name=cfg.get('metadata', 'name'),
            version=cfg.get('metadata', 'version'), platform=get_platform(),
        )

        # Convert the .exe to an unpacked egg
        egg_path = os.path.join(tmpdir, dist.egg_name() + '.egg')
        dist.location = egg_path
        egg_tmp = egg_path + '.tmp'
        _egg_info = os.path.join(egg_tmp, 'EGG-INFO')
        pkg_inf = os.path.join(_egg_info, 'PKG-INFO')
        ensure_directory(pkg_inf)  # make sure EGG-INFO dir exists
        dist._provider = PathMetadata(egg_tmp, _egg_info)  # XXX
        self.exe_to_egg(dist_filename, egg_tmp)

        # Write EGG-INFO/PKG-INFO
        if not os.path.exists(pkg_inf):
            f = open(pkg_inf, 'w')
            f.write('Metadata-Version: 1.0\n')
            for k, v in cfg.items('metadata'):
                if k != 'target_version':
                    f.write('%s: %s\n' % (k.replace('_', '-').title(), v))
            f.close()
        script_dir = os.path.join(_egg_info, 'scripts')
        # delete entry-point scripts to avoid duping
        self.delete_blockers([
            os.path.join(script_dir, args[0])
            for args in ScriptWriter.get_args(dist)
        ])
        # Build .egg file from tmpdir
        bdist_egg.make_zipfile(
            egg_path, egg_tmp, verbose=self.verbose, dry_run=self.dry_run,
        )
        # install the .egg
        return self.install_egg(egg_path, tmpdir)

    # FIXME: 'easy_install.exe_to_egg' is too complex (12)
    def exe_to_egg(self, dist_filename, egg_tmp):  # noqa: C901
        """Extract a bdist_wininst to the directories an egg would use"""
        # Check for .pth file and set up prefix translations
        prefixes = get_exe_prefixes(dist_filename)
        to_compile = []
        native_libs = []
        top_level = {}

        def process(src, dst):
            s = src.lower()
            for old, new in prefixes:
                if s.startswith(old):
                    src = new + src[len(old):]
                    parts = src.split('/')
                    dst = os.path.join(egg_tmp, *parts)
                    dl = dst.lower()
                    if dl.endswith('.pyd') or dl.endswith('.dll'):
                        parts[-1] = bdist_egg.strip_module(parts[-1])
                        top_level[os.path.splitext(parts[0])[0]] = 1
                        native_libs.append(src)
                    elif dl.endswith('.py') and old != 'SCRIPTS/':
                        top_level[os.path.splitext(parts[0])[0]] = 1
                        to_compile.append(dst)
                    return dst
            if not src.endswith('.pth'):
                log.warn("WARNING: can't process %s", src)
            return None

        # extract, tracking .pyd/.dll->native_libs and .py -> to_compile
        unpack_archive(dist_filename, egg_tmp, process)
        stubs = []
        for res in native_libs:
            if res.lower().endswith('.pyd'):  # create stubs for .pyd's
                parts = res.split('/')
                resource = parts[-1]
                parts[-1] = bdist_egg.strip_module(parts[-1]) + '.py'
                pyfile = os.path.join(egg_tmp, *parts)
                to_compile.append(pyfile)
                stubs.append(pyfile)
                bdist_egg.write_stub(resource, pyfile)
        self.byte_compile(to_compile)  # compile .py's
        bdist_egg.write_safety_flag(
            os.path.join(egg_tmp, 'EGG-INFO'),
            bdist_egg.analyze_egg(egg_tmp, stubs))  # write zip-safety flag

        for name in 'top_level', 'native_libs':
            if locals()[name]:
                txt = os.path.join(egg_tmp, 'EGG-INFO', name + '.txt')
                if not os.path.exists(txt):
                    f = open(txt, 'w')
                    f.write('\n'.join(locals()[name]) + '\n')
                    f.close()

    def install_wheel(self, wheel_path, tmpdir):
        wheel = Wheel(wheel_path)
        assert wheel.is_compatible()
        destination = os.path.join(self.install_dir, wheel.egg_name())
        destination = os.path.abspath(destination)
        if not self.dry_run:
            ensure_directory(destination)
        if os.path.isdir(destination) and not os.path.islink(destination):
            dir_util.remove_tree(destination, dry_run=self.dry_run)
        elif os.path.exists(destination):
            self.execute(
                os.unlink,
                (destination,),
                "Removing " + destination,
            )
        try:
            self.execute(
                wheel.install_as_egg,
                (destination,),
                ("Installing %s to %s") % (
                    os.path.basename(wheel_path),
                    os.path.dirname(destination)
                ),
            )
        finally:
            update_dist_caches(destination, fix_zipimporter_caches=False)
        self.add_output(destination)
        return self.egg_distribution(destination)

    __mv_warning = textwrap.dedent("""
        Because this distribution was installed --multi-version, before you can
        import modules from this package in an application, you will need to
        'import pkg_resources' and then use a 'require()' call similar to one of
        these examples, in order to select the desired version:

            pkg_resources.require("%(name)s")  # latest installed version
            pkg_resources.require("%(name)s==%(version)s")  # this exact version
            pkg_resources.require("%(name)s>=%(version)s")  # this version or higher
        """).lstrip()  # noqa

    __id_warning = textwrap.dedent("""
        Note also that the installation directory must be on sys.path at runtime for
        this to work.  (e.g. by being the application's script directory, by being on
        PYTHONPATH, or by being added to sys.path by your code.)
        """)  # noqa

    def installation_report(self, req, dist, what="Installed"):
        """Helpful installation message for display to package users"""
        msg = "\n%(what)s %(eggloc)s%(extras)s"
        if self.multi_version and not self.no_report:
            msg += '\n' + self.__mv_warning
            if self.install_dir not in map(normalize_path, sys.path):
                msg += '\n' + self.__id_warning

        eggloc = dist.location
        name = dist.project_name
        version = dist.version
        extras = ''  # TODO: self.report_extras(req, dist)
        return msg % locals()

    __editable_msg = textwrap.dedent("""
        Extracted editable version of %(spec)s to %(dirname)s

        If it uses setuptools in its setup script, you can activate it in
        "development" mode by going to that directory and running::

            %(python)s setup.py develop

        See the setuptools documentation for the "develop" command for more info.
        """).lstrip()  # noqa

    def report_editable(self, spec, setup_script):
        dirname = os.path.dirname(setup_script)
        python = sys.executable
        return '\n' + self.__editable_msg % locals()

    def run_setup(self, setup_script, setup_base, args):
        sys.modules.setdefault('distutils.command.bdist_egg', bdist_egg)
        sys.modules.setdefault('distutils.command.egg_info', egg_info)

        args = list(args)
        if self.verbose > 2:
            v = 'v' * (self.verbose - 1)
            args.insert(0, '-' + v)
        elif self.verbose < 2:
            args.insert(0, '-q')
        if self.dry_run:
            args.insert(0, '-n')
        log.info(
            "Running %s %s", setup_script[len(setup_base) + 1:], ' '.join(args)
        )
        try:
            run_setup(setup_script, args)
        except SystemExit as v:
            raise DistutilsError(
                "Setup script exited with %s" % (v.args[0],)
            ) from v

    def build_and_install(self, setup_script, setup_base):
        args = ['bdist_egg', '--dist-dir']

        dist_dir = tempfile.mkdtemp(
            prefix='egg-dist-tmp-', dir=os.path.dirname(setup_script)
        )
        try:
            self._set_fetcher_options(os.path.dirname(setup_script))
            args.append(dist_dir)

            self.run_setup(setup_script, setup_base, args)
            all_eggs = Environment([dist_dir])
            eggs = []
            for key in all_eggs:
                for dist in all_eggs[key]:
                    eggs.append(self.install_egg(dist.location, setup_base))
            if not eggs and not self.dry_run:
                log.warn("No eggs found in %s (setup script problem?)",
                         dist_dir)
            return eggs
        finally:
            rmtree(dist_dir)
            log.set_verbosity(self.verbose)  # restore our log verbosity

    def _set_fetcher_options(self, base):
        """
        When easy_install is about to run bdist_egg on a source dist, that
        source dist might have 'setup_requires' directives, requiring
        additional fetching. Ensure the fetcher options given to easy_install
        are available to that command as well.
        """
        # find the fetch options from easy_install and write them out
        # to the setup.cfg file.
        ei_opts = self.distribution.get_option_dict('easy_install').copy()
        fetch_directives = (
            'find_links', 'site_dirs', 'index_url', 'optimize', 'allow_hosts',
        )
        fetch_options = {}
        for key, val in ei_opts.items():
            if key not in fetch_directives:
                continue
            fetch_options[key.replace('_', '-')] = val[1]
        # create a settings dictionary suitable for `edit_config`
        settings = dict(easy_install=fetch_options)
        cfg_filename = os.path.join(base, 'setup.cfg')
        setopt.edit_config(cfg_filename, settings)

    def update_pth(self, dist):  # noqa: C901  # is too complex (11)  # FIXME
        if self.pth_file is None:
            return

        for d in self.pth_file[dist.key]:  # drop old entries
            if not self.multi_version and d.location == dist.location:
                continue

            log.info("Removing %s from easy-install.pth file", d)
            self.pth_file.remove(d)
            if d.location in self.shadow_path:
                self.shadow_path.remove(d.location)

        if not self.multi_version:
            if dist.location in self.pth_file.paths:
                log.info(
                    "%s is already the active version in easy-install.pth",
                    dist,
                )
            else:
                log.info("Adding %s to easy-install.pth file", dist)
                self.pth_file.add(dist)  # add new entry
                if dist.location not in self.shadow_path:
                    self.shadow_path.append(dist.location)

        if self.dry_run:
            return

        self.pth_file.save()

        if dist.key != 'setuptools':
            return

        # Ensure that setuptools itself never becomes unavailable!
        # XXX should this check for latest version?
        filename = os.path.join(self.install_dir, 'setuptools.pth')
        if os.path.islink(filename):
            os.unlink(filename)
        with open(filename, 'wt') as f:
            f.write(self.pth_file.make_relative(dist.location) + '\n')

    def unpack_progress(self, src, dst):
        # Progress filter for unpacking
        log.debug("Unpacking %s to %s", src, dst)
        return dst  # only unpack-and-compile skips files for dry run

    def unpack_and_compile(self, egg_path, destination):
        to_compile = []
        to_chmod = []

        def pf(src, dst):
            if dst.endswith('.py') and not src.startswith('EGG-INFO/'):
                to_compile.append(dst)
            elif dst.endswith('.dll') or dst.endswith('.so'):
                to_chmod.append(dst)
            self.unpack_progress(src, dst)
            return not self.dry_run and dst or None

        unpack_archive(egg_path, destination, pf)
        self.byte_compile(to_compile)
        if not self.dry_run:
            for f in to_chmod:
                mode = ((os.stat(f)[stat.ST_MODE]) | 0o555) & 0o7755
                chmod(f, mode)

    def byte_compile(self, to_compile):
        if sys.dont_write_bytecode:
            return

        from distutils.util import byte_compile

        try:
            # try to make the byte compile messages quieter
            log.set_verbosity(self.verbose - 1)

            byte_compile(to_compile, optimize=0, force=1, dry_run=self.dry_run)
            if self.optimize:
                byte_compile(
                    to_compile, optimize=self.optimize, force=1,
                    dry_run=self.dry_run,
                )
        finally:
            log.set_verbosity(self.verbose)  # restore original verbosity

    __no_default_msg = textwrap.dedent("""
        bad install directory or PYTHONPATH

        You are attempting to install a package to a directory that is not
        on PYTHONPATH and which Python does not read ".pth" files from.  The
        installation directory you specified (via --install-dir, --prefix, or
        the distutils default setting) was:

            %s

        and your PYTHONPATH environment variable currently contains:

            %r

        Here are some of your options for correcting the problem:

        * You can choose a different installation directory, i.e., one that is
          on PYTHONPATH or supports .pth files

        * You can add the installation directory to the PYTHONPATH environment
          variable.  (It must then also be on PYTHONPATH whenever you run
          Python and want to use the package(s) you are installing.)

        * You can set up the installation directory to support ".pth" files by
          using one of the approaches described here:

          https://setuptools.readthedocs.io/en/latest/easy_install.html#custom-installation-locations


        Please make the appropriate changes for your system and try again.
        """).strip()

    def create_home_path(self):
        """Create directories under ~."""
        if not self.user:
            return
        home = convert_path(os.path.expanduser("~"))
        for name, path in self.config_vars.items():
            if path.startswith(home) and not os.path.isdir(path):
                self.debug_print("os.makedirs('%s', 0o700)" % path)
                os.makedirs(path, 0o700)

    INSTALL_SCHEMES = dict(
        posix=dict(
            install_dir='$base/lib/python$py_version_short/site-packages',
            script_dir='$base/bin',
        ),
    )

    DEFAULT_SCHEME = dict(
        install_dir='$base/Lib/site-packages',
        script_dir='$base/Scripts',
    )

    def _expand(self, *attrs):
        config_vars = self.get_finalized_command('install').config_vars

        if self.prefix:
            # Set default install_dir/scripts from --prefix
            config_vars = config_vars.copy()
            config_vars['base'] = self.prefix
            scheme = self.INSTALL_SCHEMES.get(os.name, self.DEFAULT_SCHEME)
            for attr, val in scheme.items():
                if getattr(self, attr, None) is None:
                    setattr(self, attr, val)

        from distutils.util import subst_vars

        for attr in attrs:
            val = getattr(self, attr)
            if val is not None:
                val = subst_vars(val, config_vars)
                if os.name == 'posix':
                    val = os.path.expanduser(val)
                setattr(self, attr, val)


def _pythonpath():
    items = os.environ.get('PYTHONPATH', '').split(os.pathsep)
    return filter(None, items)


def get_site_dirs():
    """
    Return a list of 'site' dirs
    """

    sitedirs = []

    # start with PYTHONPATH
    sitedirs.extend(_pythonpath())

    prefixes = [sys.prefix]
    if sys.exec_prefix != sys.prefix:
        prefixes.append(sys.exec_prefix)
    for prefix in prefixes:
        if not prefix:
            continue

        if sys.platform in ('os2emx', 'riscos'):
            sitedirs.append(os.path.join(prefix, "Lib", "site-packages"))
        elif os.sep == '/':
            sitedirs.extend([
                os.path.join(
                    prefix,
                    "lib",
                    "python{}.{}".format(*sys.version_info),
                    "site-packages",
                ),
                os.path.join(prefix, "lib", "site-python"),
            ])
        else:
            sitedirs.extend([
                prefix,
                os.path.join(prefix, "lib", "site-packages"),
            ])
        if sys.platform != 'darwin':
            continue

        # for framework builds *only* we add the standard Apple
        # locations. Currently only per-user, but /Library and
        # /Network/Library could be added too
        if 'Python.framework' not in prefix:
            continue

        home = os.environ.get('HOME')
        if not home:
            continue

        home_sp = os.path.join(
            home,
            'Library',
            'Python',
            '{}.{}'.format(*sys.version_info),
            'site-packages',
        )
        sitedirs.append(home_sp)
    lib_paths = get_path('purelib'), get_path('platlib')

    sitedirs.extend(s for s in lib_paths if s not in sitedirs)

    if site.ENABLE_USER_SITE:
        sitedirs.append(site.USER_SITE)

    with contextlib.suppress(AttributeError):
        sitedirs.extend(site.getsitepackages())

    sitedirs = list(map(normalize_path, sitedirs))

    return sitedirs


def expand_paths(inputs):  # noqa: C901  # is too complex (11)  # FIXME
    """Yield sys.path directories that might contain "old-style" packages"""

    seen = {}

    for dirname in inputs:
        dirname = normalize_path(dirname)
        if dirname in seen:
            continue

        seen[dirname] = 1
        if not os.path.isdir(dirname):
            continue

        files = os.listdir(dirname)
        yield dirname, files

        for name in files:
            if not name.endswith('.pth'):
                # We only care about the .pth files
                continue
            if name in ('easy-install.pth', 'setuptools.pth'):
                # Ignore .pth files that we control
                continue

            # Read the .pth file
            f = open(os.path.join(dirname, name))
            lines = list(yield_lines(f))
            f.close()

            # Yield existing non-dupe, non-import directory lines from it
            for line in lines:
                if line.startswith("import"):
                    continue

                line = normalize_path(line.rstrip())
                if line in seen:
                    continue

                seen[line] = 1
                if not os.path.isdir(line):
                    continue

                yield line, os.listdir(line)


def extract_wininst_cfg(dist_filename):
    """Extract configuration data from a bdist_wininst .exe

    Returns a configparser.RawConfigParser, or None
    """
    f = open(dist_filename, 'rb')
    try:
        endrec = zipfile._EndRecData(f)
        if endrec is None:
            return None

        prepended = (endrec[9] - endrec[5]) - endrec[6]
        if prepended < 12:  # no wininst data here
            return None
        f.seek(prepended - 12)

        tag, cfglen, bmlen = struct.unpack("<iii", f.read(12))
        if tag not in (0x1234567A, 0x1234567B):
            return None  # not a valid tag

        f.seek(prepended - (12 + cfglen))
        init = {'version': '', 'target_version': ''}
        cfg = configparser.RawConfigParser(init)
        try:
            part = f.read(cfglen)
            # Read up to the first null byte.
            config = part.split(b'\0', 1)[0]
            # Now the config is in bytes, but for RawConfigParser, it should
            #  be text, so decode it.
            config = config.decode(sys.getfilesystemencoding())
            cfg.readfp(io.StringIO(config))
        except configparser.Error:
            return None
        if not cfg.has_section('metadata') or not cfg.has_section('Setup'):
            return None
        return cfg

    finally:
        f.close()


def get_exe_prefixes(exe_filename):
    """Get exe->egg path translations for a given .exe file"""

    prefixes = [
        ('PURELIB/', ''),
        ('PLATLIB/pywin32_system32', ''),
        ('PLATLIB/', ''),
        ('SCRIPTS/', 'EGG-INFO/scripts/'),
        ('DATA/lib/site-packages', ''),
    ]
    z = zipfile.ZipFile(exe_filename)
    try:
        for info in z.infolist():
            name = info.filename
            parts = name.split('/')
            if len(parts) == 3 and parts[2] == 'PKG-INFO':
                if parts[1].endswith('.egg-info'):
                    prefixes.insert(0, ('/'.join(parts[:2]), 'EGG-INFO/'))
                    break
            if len(parts) != 2 or not name.endswith('.pth'):
                continue
            if name.endswith('-nspkg.pth'):
                continue
            if parts[0].upper() in ('PURELIB', 'PLATLIB'):
                contents = z.read(name).decode()
                for pth in yield_lines(contents):
                    pth = pth.strip().replace('\\', '/')
                    if not pth.startswith('import'):
                        prefixes.append((('%s/%s/' % (parts[0], pth)), ''))
    finally:
        z.close()
    prefixes = [(x.lower(), y) for x, y in prefixes]
    prefixes.sort()
    prefixes.reverse()
    return prefixes


class PthDistributions(Environment):
    """A .pth file with Distribution paths in it"""

    dirty = False

    def __init__(self, filename, sitedirs=()):
        self.filename = filename
        self.sitedirs = list(map(normalize_path, sitedirs))
        self.basedir = normalize_path(os.path.dirname(self.filename))
        self._load()
        Environment.__init__(self, [], None, None)
        for path in yield_lines(self.paths):
            list(map(self.add, find_distributions(path, True)))

    def _load(self):
        self.paths = []
        saw_import = False
        seen = dict.fromkeys(self.sitedirs)
        if os.path.isfile(self.filename):
            f = open(self.filename, 'rt')
            for line in f:
                if line.startswith('import'):
                    saw_import = True
                    continue
                path = line.rstrip()
                self.paths.append(path)
                if not path.strip() or path.strip().startswith('#'):
                    continue
                # skip non-existent paths, in case somebody deleted a package
                # manually, and duplicate paths as well
                path = self.paths[-1] = normalize_path(
                    os.path.join(self.basedir, path)
                )
                if not os.path.exists(path) or path in seen:
                    self.paths.pop()  # skip it
                    self.dirty = True  # we cleaned up, so we're dirty now :)
                    continue
                seen[path] = 1
            f.close()

        if self.paths and not saw_import:
            self.dirty = True  # ensure anything we touch has import wrappers
        while self.paths and not self.paths[-1].strip():
            self.paths.pop()

    def save(self):
        """Write changed .pth file back to disk"""
        if not self.dirty:
            return

        rel_paths = list(map(self.make_relative, self.paths))
        if rel_paths:
            log.debug("Saving %s", self.filename)
            lines = self._wrap_lines(rel_paths)
            data = '\n'.join(lines) + '\n'

            if os.path.islink(self.filename):
                os.unlink(self.filename)
            with open(self.filename, 'wt') as f:
                f.write(data)

        elif os.path.exists(self.filename):
            log.debug("Deleting empty %s", self.filename)
            os.unlink(self.filename)

        self.dirty = False

    @staticmethod
    def _wrap_lines(lines):
        return lines

    def add(self, dist):
        """Add `dist` to the distribution map"""
        new_path = (
            dist.location not in self.paths and (
                dist.location not in self.sitedirs or
                # account for '.' being in PYTHONPATH
                dist.location == os.getcwd()
            )
        )
        if new_path:
            self.paths.append(dist.location)
            self.dirty = True
        Environment.add(self, dist)

    def remove(self, dist):
        """Remove `dist` from the distribution map"""
        while dist.location in self.paths:
            self.paths.remove(dist.location)
            self.dirty = True
        Environment.remove(self, dist)

    def make_relative(self, path):
        npath, last = os.path.split(normalize_path(path))
        baselen = len(self.basedir)
        parts = [last]
        sep = os.altsep == '/' and '/' or os.sep
        while len(npath) >= baselen:
            if npath == self.basedir:
                parts.append(os.curdir)
                parts.reverse()
                return sep.join(parts)
            npath, last = os.path.split(npath)
            parts.append(last)
        else:
            return path


class RewritePthDistributions(PthDistributions):
    @classmethod
    def _wrap_lines(cls, lines):
        yield cls.prelude
        for line in lines:
            yield line
        yield cls.postlude

    prelude = _one_liner("""
        import sys
        sys.__plen = len(sys.path)
        """)
    postlude = _one_liner("""
        import sys
        new = sys.path[sys.__plen:]
        del sys.path[sys.__plen:]
        p = getattr(sys, '__egginsert', 0)
        sys.path[p:p] = new
        sys.__egginsert = p + len(new)
        """)


if os.environ.get('SETUPTOOLS_SYS_PATH_TECHNIQUE', 'raw') == 'rewrite':
    PthDistributions = RewritePthDistributions


def _first_line_re():
    """
    Return a regular expression based on first_line_re suitable for matching
    strings.
    """
    if isinstance(first_line_re.pattern, str):
        return first_line_re

    # first_line_re in Python >=3.1.4 and >=3.2.1 is a bytes pattern.
    return re.compile(first_line_re.pattern.decode())


def auto_chmod(func, arg, exc):
    if func in [os.unlink, os.remove] and os.name == 'nt':
        chmod(arg, stat.S_IWRITE)
        return func(arg)
    et, ev, _ = sys.exc_info()
    # TODO: This code doesn't make sense. What is it trying to do?
    raise (ev[0], ev[1] + (" %s %s" % (func, arg)))


def update_dist_caches(dist_path, fix_zipimporter_caches):
    """
    Fix any globally cached `dist_path` related data

    `dist_path` should be a path of a newly installed egg distribution (zipped
    or unzipped).

    sys.path_importer_cache contains finder objects that have been cached when
    importing data from the original distribution. Any such finders need to be
    cleared since the replacement distribution might be packaged differently,
    e.g. a zipped egg distribution might get replaced with an unzipped egg
    folder or vice versa. Having the old finders cached may then cause Python
    to attempt loading modules from the replacement distribution using an
    incorrect loader.

    zipimport.zipimporter objects are Python loaders charged with importing
    data packaged inside zip archives. If stale loaders referencing the
    original distribution, are left behind, they can fail to load modules from
    the replacement distribution. E.g. if an old zipimport.zipimporter instance
    is used to load data from a new zipped egg archive, it may cause the
    operation to attempt to locate the requested data in the wrong location -
    one indicated by the original distribution's zip archive directory
    information. Such an operation may then fail outright, e.g. report having
    read a 'bad local file header', or even worse, it may fail silently &
    return invalid data.

    zipimport._zip_directory_cache contains cached zip archive directory
    information for all existing zipimport.zipimporter instances and all such
    instances connected to the same archive share the same cached directory
    information.

    If asked, and the underlying Python implementation allows it, we can fix
    all existing zipimport.zipimporter instances instead of having to track
    them down and remove them one by one, by updating their shared cached zip
    archive directory information. This, of course, assumes that the
    replacement distribution is packaged as a zipped egg.

    If not asked to fix existing zipimport.zipimporter instances, we still do
    our best to clear any remaining zipimport.zipimporter related cached data
    that might somehow later get used when attempting to load data from the new
    distribution and thus cause such load operations to fail. Note that when
    tracking down such remaining stale data, we can not catch every conceivable
    usage from here, and we clear only those that we know of and have found to
    cause problems if left alive. Any remaining caches should be updated by
    whomever is in charge of maintaining them, i.e. they should be ready to
    handle us replacing their zip archives with new distributions at runtime.

    """
    # There are several other known sources of stale zipimport.zipimporter
    # instances that we do not clear here, but might if ever given a reason to
    # do so:
    # * Global setuptools pkg_resources.working_set (a.k.a. 'master working
    # set') may contain distributions which may in turn contain their
    #   zipimport.zipimporter loaders.
    # * Several zipimport.zipimporter loaders held by local variables further
    #   up the function call stack when running the setuptools installation.
    # * Already loaded modules may have their __loader__ attribute set to the
    #   exact loader instance used when importing them. Python 3.4 docs state
    #   that this information is intended mostly for introspection and so is
    #   not expected to cause us problems.
    normalized_path = normalize_path(dist_path)
    _uncache(normalized_path, sys.path_importer_cache)
    if fix_zipimporter_caches:
        _replace_zip_directory_cache_data(normalized_path)
    else:
        # Here, even though we do not want to fix existing and now stale
        # zipimporter cache information, we still want to remove it. Related to
        # Python's zip archive directory information cache, we clear each of
        # its stale entries in two phases:
        #   1. Clear the entry so attempting to access zip archive information
        #      via any existing stale zipimport.zipimporter instances fails.
        #   2. Remove the entry from the cache so any newly constructed
        #      zipimport.zipimporter instances do not end up using old stale
        #      zip archive directory information.
        # This whole stale data removal step does not seem strictly necessary,
        # but has been left in because it was done before we started replacing
        # the zip archive directory information cache content if possible, and
        # there are no relevant unit tests that we can depend on to tell us if
        # this is really needed.
        _remove_and_clear_zip_directory_cache_data(normalized_path)


def _collect_zipimporter_cache_entries(normalized_path, cache):
    """
    Return zipimporter cache entry keys related to a given normalized path.

    Alternative path spellings (e.g. those using different character case or
    those using alternative path separators) related to the same path are
    included. Any sub-path entries are included as well, i.e. those
    corresponding to zip archives embedded in other zip archives.

    """
    result = []
    prefix_len = len(normalized_path)
    for p in cache:
        np = normalize_path(p)
        if (np.startswith(normalized_path) and
                np[prefix_len:prefix_len + 1] in (os.sep, '')):
            result.append(p)
    return result


def _update_zipimporter_cache(normalized_path, cache, updater=None):
    """
    Update zipimporter cache data for a given normalized path.

    Any sub-path entries are processed as well, i.e. those corresponding to zip
    archives embedded in other zip archives.

    Given updater is a callable taking a cache entry key and the original entry
    (after already removing the entry from the cache), and expected to update
    the entry and possibly return a new one to be inserted in its place.
    Returning None indicates that the entry should not be replaced with a new
    one. If no updater is given, the cache entries are simply removed without
    any additional processing, the same as if the updater simply returned None.

    """
    for p in _collect_zipimporter_cache_entries(normalized_path, cache):
        # N.B. pypy's custom zipimport._zip_directory_cache implementation does
        # not support the complete dict interface:
        # * Does not support item assignment, thus not allowing this function
        #    to be used only for removing existing cache entries.
        #  * Does not support the dict.pop() method, forcing us to use the
        #    get/del patterns instead. For more detailed information see the
        #    following links:
        #      https://github.com/pypa/setuptools/issues/202#issuecomment-202913420
        #      http://bit.ly/2h9itJX
        old_entry = cache[p]
        del cache[p]
        new_entry = updater and updater(p, old_entry)
        if new_entry is not None:
            cache[p] = new_entry


def _uncache(normalized_path, cache):
    _update_zipimporter_cache(normalized_path, cache)


def _remove_and_clear_zip_directory_cache_data(normalized_path):
    def clear_and_remove_cached_zip_archive_directory_data(path, old_entry):
        old_entry.clear()

    _update_zipimporter_cache(
        normalized_path, zipimport._zip_directory_cache,
        updater=clear_and_remove_cached_zip_archive_directory_data)


# PyPy Python implementation does not allow directly writing to the
# zipimport._zip_directory_cache and so prevents us from attempting to correct
# its content. The best we can do there is clear the problematic cache content
# and have PyPy repopulate it as needed. The downside is that if there are any
# stale zipimport.zipimporter instances laying around, attempting to use them
# will fail due to not having its zip archive directory information available
# instead of being automatically corrected to use the new correct zip archive
# directory information.
if '__pypy__' in sys.builtin_module_names:
    _replace_zip_directory_cache_data = \
        _remove_and_clear_zip_directory_cache_data
else:

    def _replace_zip_directory_cache_data(normalized_path):
        def replace_cached_zip_archive_directory_data(path, old_entry):
            # N.B. In theory, we could load the zip directory information just
            # once for all updated path spellings, and then copy it locally and
            # update its contained path strings to contain the correct
            # spelling, but that seems like a way too invasive move (this cache
            # structure is not officially documented anywhere and could in
            # theory change with new Python releases) for no significant
            # benefit.
            old_entry.clear()
            zipimport.zipimporter(path)
            old_entry.update(zipimport._zip_directory_cache[path])
            return old_entry

        _update_zipimporter_cache(
            normalized_path, zipimport._zip_directory_cache,
            updater=replace_cached_zip_archive_directory_data)


def is_python(text, filename='<string>'):
    "Is this string a valid Python script?"
    try:
        compile(text, filename, 'exec')
    except (SyntaxError, TypeError):
        return False
    else:
        return True


def is_sh(executable):
    """Determine if the specified executable is a .sh (contains a #! line)"""
    try:
        with io.open(executable, encoding='latin-1') as fp:
            magic = fp.read(2)
    except (OSError, IOError):
        return executable
    return magic == '#!'


def nt_quote_arg(arg):
    """Quote a command line argument according to Windows parsing rules"""
    return subprocess.list2cmdline([arg])


def is_python_script(script_text, filename):
    """Is this text, as a whole, a Python script? (as opposed to shell/bat/etc.
    """
    if filename.endswith('.py') or filename.endswith('.pyw'):
        return True  # extension says it's Python
    if is_python(script_text, filename):
        return True  # it's syntactically valid Python
    if script_text.startswith('#!'):
        # It begins with a '#!' line, so check if 'python' is in it somewhere
        return 'python' in script_text.splitlines()[0].lower()

    return False  # Not any Python I can recognize


try:
    from os import chmod as _chmod
except ImportError:
    # Jython compatibility
    def _chmod(*args):
        pass


def chmod(path, mode):
    log.debug("changing mode of %s to %o", path, mode)
    try:
        _chmod(path, mode)
    except os.error as e:
        log.debug("chmod failed: %s", e)


class CommandSpec(list):
    """
    A command spec for a #! header, specified as a list of arguments akin to
    those passed to Popen.
    """

    options = []
    split_args = dict()

    @classmethod
    def best(cls):
        """
        Choose the best CommandSpec class based on environmental conditions.
        """
        return cls

    @classmethod
    def _sys_executable(cls):
        _default = os.path.normpath(sys.executable)
        return os.environ.get('__PYVENV_LAUNCHER__', _default)

    @classmethod
    def from_param(cls, param):
        """
        Construct a CommandSpec from a parameter to build_scripts, which may
        be None.
        """
        if isinstance(param, cls):
            return param
        if isinstance(param, list):
            return cls(param)
        if param is None:
            return cls.from_environment()
        # otherwise, assume it's a string.
        return cls.from_string(param)

    @classmethod
    def from_environment(cls):
        return cls([cls._sys_executable()])

    @classmethod
    def from_string(cls, string):
        """
        Construct a command spec from a simple string representing a command
        line parseable by shlex.split.
        """
        items = shlex.split(string, **cls.split_args)
        return cls(items)

    def install_options(self, script_text):
        self.options = shlex.split(self._extract_options(script_text))
        cmdline = subprocess.list2cmdline(self)
        if not isascii(cmdline):
            self.options[:0] = ['-x']

    @staticmethod
    def _extract_options(orig_script):
        """
        Extract any options from the first line of the script.
        """
        first = (orig_script + '\n').splitlines()[0]
        match = _first_line_re().match(first)
        options = match.group(1) or '' if match else ''
        return options.strip()

    def as_header(self):
        return self._render(self + list(self.options))

    @staticmethod
    def _strip_quotes(item):
        _QUOTES = '"\''
        for q in _QUOTES:
            if item.startswith(q) and item.endswith(q):
                return item[1:-1]
        return item

    @staticmethod
    def _render(items):
        cmdline = subprocess.list2cmdline(
            CommandSpec._strip_quotes(item.strip()) for item in items)
        return '#!' + cmdline + '\n'


# For pbr compat; will be removed in a future version.
sys_executable = CommandSpec._sys_executable()


class WindowsCommandSpec(CommandSpec):
    split_args = dict(posix=False)


class ScriptWriter:
    """
    Encapsulates behavior around writing entry point scripts for console and
    gui apps.
    """

    template = textwrap.dedent(r"""
        # EASY-INSTALL-ENTRY-SCRIPT: %(spec)r,%(group)r,%(name)r
        import re
        import sys

        # for compatibility with easy_install; see #2198
        __requires__ = %(spec)r

        try:
            from importlib.metadata import distribution
        except ImportError:
            try:
                from importlib_metadata import distribution
            except ImportError:
                from pkg_resources import load_entry_point


        def importlib_load_entry_point(spec, group, name):
            dist_name, _, _ = spec.partition('==')
            matches = (
                entry_point
                for entry_point in distribution(dist_name).entry_points
                if entry_point.group == group and entry_point.name == name
            )
            return next(matches).load()


        globals().setdefault('load_entry_point', importlib_load_entry_point)


        if __name__ == '__main__':
            sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])
            sys.exit(load_entry_point(%(spec)r, %(group)r, %(name)r)())
        """).lstrip()

    command_spec_class = CommandSpec

    @classmethod
    def get_script_args(cls, dist, executable=None, wininst=False):
        # for backward compatibility
        warnings.warn("Use get_args", EasyInstallDeprecationWarning)
        writer = (WindowsScriptWriter if wininst else ScriptWriter).best()
        header = cls.get_script_header("", executable, wininst)
        return writer.get_args(dist, header)

    @classmethod
    def get_script_header(cls, script_text, executable=None, wininst=False):
        # for backward compatibility
        warnings.warn(
            "Use get_header", EasyInstallDeprecationWarning, stacklevel=2)
        if wininst:
            executable = "python.exe"
        return cls.get_header(script_text, executable)

    @classmethod
    def get_args(cls, dist, header=None):
        """
        Yield write_script() argument tuples for a distribution's
        console_scripts and gui_scripts entry points.
        """
        if header is None:
            header = cls.get_header()
        spec = str(dist.as_requirement())
        for type_ in 'console', 'gui':
            group = type_ + '_scripts'
            for name, ep in dist.get_entry_map(group).items():
                cls._ensure_safe_name(name)
                script_text = cls.template % locals()
                args = cls._get_script_args(type_, name, header, script_text)
                for res in args:
                    yield res

    @staticmethod
    def _ensure_safe_name(name):
        """
        Prevent paths in *_scripts entry point names.
        """
        has_path_sep = re.search(r'[\\/]', name)
        if has_path_sep:
            raise ValueError("Path separators not allowed in script names")

    @classmethod
    def get_writer(cls, force_windows):
        # for backward compatibility
        warnings.warn("Use best", EasyInstallDeprecationWarning)
        return WindowsScriptWriter.best() if force_windows else cls.best()

    @classmethod
    def best(cls):
        """
        Select the best ScriptWriter for this environment.
        """
        if sys.platform == 'win32' or (os.name == 'java' and os._name == 'nt'):
            return WindowsScriptWriter.best()
        else:
            return cls

    @classmethod
    def _get_script_args(cls, type_, name, header, script_text):
        # Simply write the stub with no extension.
        yield (name, header + script_text)

    @classmethod
    def get_header(cls, script_text="", executable=None):
        """Create a #! line, getting options (if any) from script_text"""
        cmd = cls.command_spec_class.best().from_param(executable)
        cmd.install_options(script_text)
        return cmd.as_header()


class WindowsScriptWriter(ScriptWriter):
    command_spec_class = WindowsCommandSpec

    @classmethod
    def get_writer(cls):
        # for backward compatibility
        warnings.warn("Use best", EasyInstallDeprecationWarning)
        return cls.best()

    @classmethod
    def best(cls):
        """
        Select the best ScriptWriter suitable for Windows
        """
        writer_lookup = dict(
            executable=WindowsExecutableLauncherWriter,
            natural=cls,
        )
        # for compatibility, use the executable launcher by default
        launcher = os.environ.get('SETUPTOOLS_LAUNCHER', 'executable')
        return writer_lookup[launcher]

    @classmethod
    def _get_script_args(cls, type_, name, header, script_text):
        "For Windows, add a .py extension"
        ext = dict(console='.pya', gui='.pyw')[type_]
        if ext not in os.environ['PATHEXT'].lower().split(';'):
            msg = (
                "{ext} not listed in PATHEXT; scripts will not be "
                "recognized as executables."
            ).format(**locals())
            warnings.warn(msg, UserWarning)
        old = ['.pya', '.py', '-script.py', '.pyc', '.pyo', '.pyw', '.exe']
        old.remove(ext)
        header = cls._adjust_header(type_, header)
        blockers = [name + x for x in old]
        yield name + ext, header + script_text, 't', blockers

    @classmethod
    def _adjust_header(cls, type_, orig_header):
        """
        Make sure 'pythonw' is used for gui and and 'python' is used for
        console (regardless of what sys.executable is).
        """
        pattern = 'pythonw.exe'
        repl = 'python.exe'
        if type_ == 'gui':
            pattern, repl = repl, pattern
        pattern_ob = re.compile(re.escape(pattern), re.IGNORECASE)
        new_header = pattern_ob.sub(string=orig_header, repl=repl)
        return new_header if cls._use_header(new_header) else orig_header

    @staticmethod
    def _use_header(new_header):
        """
        Should _adjust_header use the replaced header?

        On non-windows systems, always use. On
        Windows systems, only use the replaced header if it resolves
        to an executable on the system.
        """
        clean_header = new_header[2:-1].strip('"')
        return sys.platform != 'win32' or find_executable(clean_header)


class WindowsExecutableLauncherWriter(WindowsScriptWriter):
    @classmethod
    def _get_script_args(cls, type_, name, header, script_text):
        """
        For Windows, add a .py extension and an .exe launcher
        """
        if type_ == 'gui':
            launcher_type = 'gui'
            ext = '-script.pyw'
            old = ['.pyw']
        else:
            launcher_type = 'cli'
            ext = '-script.py'
            old = ['.py', '.pyc', '.pyo']
        hdr = cls._adjust_header(type_, header)
        blockers = [name + x for x in old]
        yield (name + ext, hdr + script_text, 't', blockers)
        yield (
            name + '.exe', get_win_launcher(launcher_type),
            'b'  # write in binary mode
        )
        if not is_64bit():
            # install a manifest for the launcher to prevent Windows
            # from detecting it as an installer (which it will for
            #  launchers like easy_install.exe). Consider only
            #  adding a manifest for launchers detected as installers.
            #  See Distribute #143 for details.
            m_name = name + '.exe.manifest'
            yield (m_name, load_launcher_manifest(name), 't')


# for backward-compatibility
get_script_args = ScriptWriter.get_script_args
get_script_header = ScriptWriter.get_script_header


def get_win_launcher(type):
    """
    Load the Windows launcher (executable) suitable for launching a script.

    `type` should be either 'cli' or 'gui'

    Returns the executable as a byte string.
    """
    launcher_fn = '%s.exe' % type
    if is_64bit():
        launcher_fn = launcher_fn.replace(".", "-64.")
    else:
        launcher_fn = launcher_fn.replace(".", "-32.")
    return resource_string('setuptools', launcher_fn)


def load_launcher_manifest(name):
    manifest = pkg_resources.resource_string(__name__, 'launcher manifest.xml')
    return manifest.decode('utf-8') % vars()


def rmtree(path, ignore_errors=False, onerror=auto_chmod):
    return shutil.rmtree(path, ignore_errors, onerror)


def current_umask():
    tmp = os.umask(0o022)
    os.umask(tmp)
    return tmp


def main(argv=None, **kw):
    from setuptools import setup
    from setuptools.dist import Distribution

    class DistributionWithoutHelpCommands(Distribution):
        common_usage = ""

        def _show_help(self, *args, **kw):
            with _patch_usage():
                Distribution._show_help(self, *args, **kw)

    if argv is None:
        argv = sys.argv[1:]

    with _patch_usage():
        setup(
            script_args=['-q', 'easy_install', '-v'] + argv,
            script_name=sys.argv[0] or 'easy_install',
            distclass=DistributionWithoutHelpCommands,
            **kw
        )


@contextlib.contextmanager
def _patch_usage():
    import distutils.core
    USAGE = textwrap.dedent("""
        usage: %(script)s [options] requirement_or_url ...
           or: %(script)s --help
        """).lstrip()

    def gen_usage(script_name):
        return USAGE % dict(
            script=os.path.basename(script_name),
        )

    saved = distutils.core.gen_usage
    distutils.core.gen_usage = gen_usage
    try:
        yield
    finally:
        distutils.core.gen_usage = saved


class EasyInstallDeprecationWarning(SetuptoolsDeprecationWarning):
    """
    Warning for EasyInstall deprecations, bypassing suppression.
    """