ez_setup.py

#!/usr/bin/env python
"""Bootstrap setuptools installation

To use setuptools in your package's setup.py, include this
file in the same directory and add this to the top of your setup.py::

    from ez_setup import use_setuptools
    use_setuptools()

To require a specific version of setuptools, set a download
mirror, or use an alternate download directory, simply supply
the appropriate options to ``use_setuptools()``.

This file can also be run as a script to install or upgrade setuptools.
"""
from __future__ import absolute_import
import os
import shutil
import sys
import tempfile
import zipfile
import optparse
import subprocess
import platform
import contextlib

from distutils import log

try:
    from urllib.request import urlopen
except ImportError:
    from six.moves.urllib import urlopen

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

DEFAULT_VERSION = "6.1"
DEFAULT_URL = "https://pypi.python.org/packages/source/s/setuptools/"


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


def _install(archive_filename, install_args=()):
    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):
    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 IOError('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(ContextualZipFile, cls).__new__(cls)


@contextlib.contextmanager
def archive_context(filename):
    # extracting the archive
    tmpdir = tempfile.mkdtemp()
    log.warn('Extracting in %s', tmpdir)
    old_wd = os.getcwd()
    try:
        os.chdir(tmpdir)
        with ContextualZipFile(filename) as archive:
            archive.extractall()

        # 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):
    egg = os.path.join(to_dir, 'setuptools-%s-py%d.%d.egg'
                       % (version, sys.version_info[0], sys.version_info[1]))
    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:
        del sys.modules['pkg_resources']

    import setuptools
    setuptools.bootstrap_install_from = egg


def use_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
                   to_dir=os.curdir, download_delay=15):
    to_dir = os.path.abspath(to_dir)
    rep_modules = 'pkg_resources', 'setuptools'
    imported = set(sys.modules).intersection(rep_modules)
    try:
        import pkg_resources
    except ImportError:
        return _do_download(version, download_base, to_dir, download_delay)
    try:
        pkg_resources.require("setuptools>=" + version)
        return
    except pkg_resources.DistributionNotFound:
        return _do_download(version, download_base, to_dir, download_delay)
    except pkg_resources.VersionConflict as VC_err:
        if imported:
            msg = """\
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})
""".format(VC_err=VC_err, version=version)
            sys.stderr.write(msg)
            sys.exit(2)

        # otherwise, reload ok
        del pkg_resources, sys.modules['pkg_resources']
        return _do_download(version, download_base, to_dir, download_delay)


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 (which 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)r, %(target)r)"
        % vars()
    )
    cmd = [
        'powershell',
        '-Command',
        ps_cmd,
    ]
    _clean_check(cmd, target)


def has_powershell():
    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, '--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, even though it cannot authenticate the
    connection.
    """
    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=os.curdir, 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 = "setuptools-%s.zip" % version
    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
    """
    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 (requires Python 2.6 or later)')
    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,
    )
    options, args = parser.parse_args()
    # positional arguments are ignored
    return options


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


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