ez_setup.py

#!/usr/bin/env python

"""
Setuptools bootstrapping installer.

Maintained at https://github.com/pypa/setuptools/tree/bootstrap.

Run this script to install or upgrade setuptools.

This method is DEPRECATED. Check https://github.com/pypa/setuptools/issues/581 for more details.
"""

import os
import shutil
import sys
import tempfile
import zipfile
import optparse
import subprocess
import platform
import textwrap
import contextlib

from distutils import log

try:
    from urllib.request import urlopen
except ImportError:
    from urllib2 import urlopen

try:
    from site import USER_SITE
except ImportError:
    USER_SITE = None

# 33.1.1 is the last version that supports setuptools self upgrade/installation.
DEFAULT_VERSION = "33.1.1"
DEFAULT_URL = "https://pypi.io/packages/source/s/setuptools/"
DEFAULT_SAVE_DIR = os.curdir
DEFAULT_DEPRECATION_MESSAGE = "ez_setup.py is deprecated and when using it setuptools will be pinned to {0} since it's the last version that supports setuptools self upgrade/installation, check https://github.com/pypa/setuptools/issues/581 for more info; use pip to install setuptools"

MEANINGFUL_INVALID_ZIP_ERR_MSG = 'Maybe {0} is corrupted, delete it and try again.'

log.warn(DEFAULT_DEPRECATION_MESSAGE.format(DEFAULT_VERSION))


def _python_cmd(*args):
    """
    Execute a command.

    Return True if the command succeeded.
    """
    args = (sys.executable,) + args
    return subprocess.call(args) == 0


def _install(archive_filename, install_args=()):
    """Install Setuptools."""
    with archive_context(archive_filename):
        # installing
        log.warn('Installing Setuptools')
        if not _python_cmd('setup.py', 'install', *install_args):
            log.warn('Something went wrong during the installation.')
            log.warn('See the error message above.')
            # exitcode will be 2
            return 2


def _build_egg(egg, archive_filename, to_dir):
    """Build Setuptools egg."""
    with archive_context(archive_filename):
        # building an egg
        log.warn('Building a Setuptools egg in %s', to_dir)
        _python_cmd('setup.py', '-q', 'bdist_egg', '--dist-dir', to_dir)
    # returning the result
    log.warn(egg)
    if not os.path.exists(egg):
        raise OSError('Could not build the egg.')


class ContextualZipFile(zipfile.ZipFile):

    """Supplement ZipFile class to support context manager for Python 2.6."""

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.close()

    def __new__(cls, *args, **kwargs):
        """Construct a ZipFile or ContextualZipFile as appropriate."""
        if hasattr(zipfile.ZipFile, '__exit__'):
            return zipfile.ZipFile(*args, **kwargs)
        return super().__new__(cls)


@contextlib.contextmanager
def archive_context(filename):
    """
    Unzip filename to a temporary directory, set to the cwd.

    The unzipped target is cleaned up after.
    """
    tmpdir = tempfile.mkdtemp()
    log.warn('Extracting in %s', tmpdir)
    old_wd = os.getcwd()
    try:
        os.chdir(tmpdir)
        try:
            with ContextualZipFile(filename) as archive:
                archive.extractall()
        except zipfile.BadZipFile as err:
            if not err.args:
                err.args = ('', )
            err.args = err.args + (
                MEANINGFUL_INVALID_ZIP_ERR_MSG.format(filename),
            )
            raise

        # going in the directory
        subdir = os.path.join(tmpdir, os.listdir(tmpdir)[0])
        os.chdir(subdir)
        log.warn('Now working in %s', subdir)
        yield

    finally:
        os.chdir(old_wd)
        shutil.rmtree(tmpdir)


def _do_download(version, download_base, to_dir, download_delay):
    """Download Setuptools."""
    py_desig = f'py{sys.version_info[0]}.{sys.version_info[1]}'
    tp = f'setuptools-{version}-{py_desig}.egg'
    egg = os.path.join(to_dir, tp.format(**locals()))
    if not os.path.exists(egg):
        archive = download_setuptools(version, download_base,
            to_dir, download_delay)
        _build_egg(egg, archive, to_dir)
    sys.path.insert(0, egg)

    # Remove previously-imported pkg_resources if present (see
    # https://bitbucket.org/pypa/setuptools/pull-request/7/ for details).
    if 'pkg_resources' in sys.modules:
        _unload_pkg_resources()

    import setuptools
    setuptools.bootstrap_install_from = egg


def use_setuptools(
        version=DEFAULT_VERSION, download_base=DEFAULT_URL,
        to_dir=DEFAULT_SAVE_DIR, download_delay=15):
    """
    Ensure that a setuptools version is installed.

    Return None. Raise SystemExit if the requested version
    or later cannot be installed.
    """
    to_dir = os.path.abspath(to_dir)

    # prior to importing, capture the module state for
    # representative modules.
    rep_modules = 'pkg_resources', 'setuptools'
    imported = set(sys.modules).intersection(rep_modules)

    try:
        import pkg_resources
        pkg_resources.require("setuptools>=" + version)
        # a suitable version is already installed
        return
    except ImportError:
        # pkg_resources not available; setuptools is not installed; download
        pass
    except pkg_resources.DistributionNotFound:
        # no version of setuptools was found; allow download
        pass
    except pkg_resources.VersionConflict as VC_err:
        if imported:
            _conflict_bail(VC_err, version)

        # otherwise, unload pkg_resources to allow the downloaded version to
        #  take precedence.
        del pkg_resources
        _unload_pkg_resources()

    return _do_download(version, download_base, to_dir, download_delay)


def _conflict_bail(VC_err, version):
    """
    Setuptools was imported prior to invocation, so it is
    unsafe to unload it. Bail out.
    """
    conflict_tmpl = textwrap.dedent(f"""
        The required version of setuptools (>={version}) is not available,
        and can't be installed while this script is running. Please
        install a more recent version first, using
        'easy_install -U setuptools'.

        (Currently using {VC_err.args[0]!r})
        """)
    msg = conflict_tmpl.format(**locals())
    sys.stderr.write(msg)
    sys.exit(2)


def _unload_pkg_resources():
    sys.meta_path = [
        importer
        for importer in sys.meta_path
        if importer.__class__.__module__ != 'pkg_resources.extern'
    ]
    del_modules = [
        name for name in sys.modules
        if name.startswith('pkg_resources')
    ]
    for mod_name in del_modules:
        del sys.modules[mod_name]


def _clean_check(cmd, target):
    """
    Run the command to download target.

    If the command fails, clean up before re-raising the error.
    """
    try:
        subprocess.check_call(cmd)
    except subprocess.CalledProcessError:
        if os.access(target, os.F_OK):
            os.unlink(target)
        raise


def download_file_powershell(url, target):
    """
    Download the file at url to target using Powershell.

    Powershell will validate trust.
    Raise an exception if the command cannot complete.
    """
    target = os.path.abspath(target)
    ps_cmd = (
        "[System.Net.WebRequest]::DefaultWebProxy.Credentials = "
        "[System.Net.CredentialCache]::DefaultCredentials; "
        '(new-object System.Net.WebClient).DownloadFile("{url}", "{target}")'.format(**locals())
    )
    cmd = [
        'powershell',
        '-Command',
        ps_cmd,
    ]
    _clean_check(cmd, target)


def has_powershell():
    """Determine if Powershell is available."""
    if platform.system() != 'Windows':
        return False
    cmd = ['powershell', '-Command', 'echo test']
    with open(os.path.devnull, 'wb') as devnull:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except Exception:
            return False
    return True
download_file_powershell.viable = has_powershell


def download_file_curl(url, target):
    cmd = ['curl', url, '--location', '--silent', '--output', target]
    _clean_check(cmd, target)


def has_curl():
    cmd = ['curl', '--version']
    with open(os.path.devnull, 'wb') as devnull:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except Exception:
            return False
    return True
download_file_curl.viable = has_curl


def download_file_wget(url, target):
    cmd = ['wget', url, '--quiet', '--output-document', target]
    _clean_check(cmd, target)


def has_wget():
    cmd = ['wget', '--version']
    with open(os.path.devnull, 'wb') as devnull:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except Exception:
            return False
    return True
download_file_wget.viable = has_wget


def download_file_insecure(url, target):
    """Use Python to download the file, without connection authentication."""
    src = urlopen(url)
    try:
        # Read all the data in one block.
        data = src.read()
    finally:
        src.close()

    # Write all the data in one block to avoid creating a partial file.
    with open(target, "wb") as dst:
        dst.write(data)
download_file_insecure.viable = lambda: True


def get_best_downloader():
    downloaders = (
        download_file_powershell,
        download_file_curl,
        download_file_wget,
        download_file_insecure,
    )
    viable_downloaders = (dl for dl in downloaders if dl.viable())
    return next(viable_downloaders, None)


def download_setuptools(
        version=DEFAULT_VERSION, download_base=DEFAULT_URL,
        to_dir=DEFAULT_SAVE_DIR, delay=15,
        downloader_factory=get_best_downloader):
    """
    Download setuptools from a specified location and return its filename.

    `version` should be a valid setuptools version number that is available
    as an sdist for download under the `download_base` URL (which should end
    with a '/'). `to_dir` is the directory where the egg will be downloaded.
    `delay` is the number of seconds to pause before an actual download
    attempt.

    ``downloader_factory`` should be a function taking no arguments and
    returning a function for downloading a URL to a target.
    """
    # making sure we use the absolute path
    to_dir = os.path.abspath(to_dir)
    zip_name = f"setuptools-{version}.zip"
    url = download_base + zip_name
    saveto = os.path.join(to_dir, zip_name)
    if not os.path.exists(saveto):  # Avoid repeated downloads
        log.warn("Downloading %s", url)
        downloader = downloader_factory()
        downloader(url, saveto)
    return os.path.realpath(saveto)


def _build_install_args(options):
    """
    Build the arguments to 'python setup.py install' on the setuptools package.

    Returns list of command line arguments.
    """
    return ['--user'] if options.user_install else []


def _parse_args():
    """Parse the command line for options."""
    parser = optparse.OptionParser()
    parser.add_option(
        '--user', dest='user_install', action='store_true', default=False,
        help='install in user site package')
    parser.add_option(
        '--download-base', dest='download_base', metavar="URL",
        default=DEFAULT_URL,
        help='alternative URL from where to download the setuptools package')
    parser.add_option(
        '--insecure', dest='downloader_factory', action='store_const',
        const=lambda: download_file_insecure, default=get_best_downloader,
        help='Use internal, non-validating downloader'
    )
    parser.add_option(
        '--version', help="Specify which version to download",
        default=DEFAULT_VERSION,
    )
    parser.add_option(
        '--to-dir',
        help="Directory to save (and reuse) package",
        default=DEFAULT_SAVE_DIR,
    )
    options, _ = parser.parse_args()
    return options


def _download_args(options):
    """Return args for download_setuptools function from cmdline args."""
    return dict(
        version=options.version,
        download_base=options.download_base,
        downloader_factory=options.downloader_factory,
        to_dir=options.to_dir,
    )


def main():
    """Install or upgrade setuptools and EasyInstall."""
    options = _parse_args()
    archive = download_setuptools(**_download_args(options))
    return _install(archive, _build_install_args(options))

if __name__ == '__main__':
    sys.exit(main())