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.
"""
import os
import shutil
import sys
import tempfile
import tarfile
import optparse
import subprocess
import platform
import textwrap

from distutils import log

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

DEFAULT_VERSION = "2.2"
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(tarball, install_args=()):
    # extracting the tarball
    tmpdir = tempfile.mkdtemp()
    log.warn('Extracting in %s', tmpdir)
    old_wd = os.getcwd()
    try:
        os.chdir(tmpdir)
        tar = tarfile.open(tarball)
        _extractall(tar)
        tar.close()

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

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


def _build_egg(egg, tarball, to_dir):
    # extracting the tarball
    tmpdir = tempfile.mkdtemp()
    log.warn('Extracting in %s', tmpdir)
    old_wd = os.getcwd()
    try:
        os.chdir(tmpdir)
        tar = tarfile.open(tarball)
        _extractall(tar)
        tar.close()

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

        # building an egg
        log.warn('Building a Setuptools egg in %s', to_dir)
        _python_cmd('setup.py', '-q', 'bdist_egg', '--dist-dir', to_dir)

    finally:
        os.chdir(old_wd)
        shutil.rmtree(tmpdir)
    # returning the result
    log.warn(egg)
    if not os.path.exists(egg):
        raise IOError('Could not build the egg.')


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):
        tarball = download_setuptools(version, download_base,
                                      to_dir, download_delay)
        _build_egg(egg, tarball, 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 = textwrap.dedent("""
                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)
    cmd = [
        'powershell',
        '-Command',
        "(new-object System.Net.WebClient).DownloadFile(%(url)r, %(target)r)" % vars(),
    ]
    _clean_check(cmd, target)


def has_powershell():
    if platform.system() != 'Windows':
        return False
    cmd = ['powershell', '-Command', 'echo test']
    devnull = open(os.path.devnull, 'wb')
    try:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except:
            return False
    finally:
        devnull.close()
    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']
    devnull = open(os.path.devnull, 'wb')
    try:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except:
            return False
    finally:
        devnull.close()
    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']
    devnull = open(os.path.devnull, 'wb')
    try:
        try:
            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
        except:
            return False
    finally:
        devnull.close()
    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.
    """
    try:
        from urllib.request import urlopen
    except ImportError:
        from urllib2 import urlopen
    src = dst = None
    try:
        src = urlopen(url)
        # Read/write all in one block, so we don't create a corrupt file
        # if the download is interrupted.
        data = src.read()
        dst = open(target, "wb")
        dst.write(data)
    finally:
        if src:
            src.close()
        if dst:
            dst.close()

download_file_insecure.viable = lambda: True


def get_best_downloader():
    downloaders = [
        download_file_powershell,
        download_file_curl,
        download_file_wget,
        download_file_insecure,
    ]

    for dl in downloaders:
        if dl.viable():
            return dl


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 egg 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)
    tgz_name = "setuptools-%s.tar.gz" % version
    url = download_base + tgz_name
    saveto = os.path.join(to_dir, tgz_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 _extractall(self, path=".", members=None):
    """Extract all members from the archive to the current working
       directory and set owner, modification time and permissions on
       directories afterwards. `path' specifies a different directory
       to extract to. `members' is optional and must be a subset of the
       list returned by getmembers().
    """
    import copy
    import operator
    from tarfile import ExtractError
    directories = []

    if members is None:
        members = self

    for tarinfo in members:
        if tarinfo.isdir():
            # Extract directories with a safe mode.
            directories.append(tarinfo)
            tarinfo = copy.copy(tarinfo)
            tarinfo.mode = 448  # decimal for oct 0700
        self.extract(tarinfo, path)

    # Reverse sort directories.
    directories.sort(key=operator.attrgetter('name'), reverse=True)

    # Set correct owner, mtime and filemode on directories.
    for tarinfo in directories:
        dirpath = os.path.join(path, tarinfo.name)
        try:
            self.chown(tarinfo, dirpath)
            self.utime(tarinfo, dirpath)
            self.chmod(tarinfo, dirpath)
        except ExtractError as e:
            if self.errorlevel > 1:
                raise
            else:
                self._dbg(1, "tarfile: %s" % e)


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'
    )
    options, args = parser.parse_args()
    # positional arguments are ignored
    return options


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

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