installinstallmacos.py

#!/usr/bin/python
# encoding: utf-8
#
# Copyright 2017 Greg Neagle.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Thanks to Tim Sutton for ideas, suggestions, and sample code.
#

'''installinstallmacos.py
A tool to download the parts for an Install macOS app from Apple's
softwareupdate servers and install a functioning Install macOS app onto an
empty disk image'''


import argparse
import os
import plistlib
import subprocess
import sys
import urlparse
from xml.dom import minidom
from xml.parsers.expat import ExpatError


DEFAULT_SUCATALOG = (
    'https://swscan.apple.com/content/catalogs/others/'
    'index-10.13seed-10.13-10.12-10.11-10.10-10.9'
    '-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog')


def make_sparse_image(volume_name, output_path):
    '''Make a sparse disk image we can install a product to'''
    cmd = ['/usr/bin/hdiutil', 'create', '-size', '8g', '-fs', 'HFS+',
           '-volname', volume_name, '-type', 'SPARSE', '-plist', output_path]
    try:
        output = subprocess.check_output(cmd)
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
        exit(-1)
    try:
        return plistlib.readPlistFromString(output)[0]
    except IndexError, err:
        print >> sys.stderr, 'Unexpected output from hdiutil: %s' % output
        exit(-1)
    except ExpatError, err:
        print >> sys.stderr, 'Malformed output from hdiutil: %s' % output
        print >> sys.stderr, err
        exit(-1)


def make_compressed_dmg(app_path, diskimagepath):
    """Returns path to newly-created compressed r/o disk image containing
    Install macOS.app"""

    print ('Making read-only compressed disk image containing %s...'
           % os.path.basename(app_path))
    cmd = ['/usr/bin/hdiutil', 'create', '-fs', 'HFS+',
           '-srcfolder', app_path, diskimagepath]
    try:
        subprocess.check_call(cmd)
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
    else:
        print 'Disk image created at: %s' % diskimagepath


def mountdmg(dmgpath):
    """
    Attempts to mount the dmg at dmgpath and returns first mountpoint
    """
    mountpoints = []
    dmgname = os.path.basename(dmgpath)
    cmd = ['/usr/bin/hdiutil', 'attach', dmgpath,
           '-mountRandom', '/tmp', '-nobrowse', '-plist',
           '-owners', 'on']
    proc = subprocess.Popen(cmd, bufsize=-1,
                            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    (pliststr, err) = proc.communicate()
    if proc.returncode:
        print >> sys.stderr, 'Error: "%s" while mounting %s.' % (err, dmgname)
        return None
    if pliststr:
        plist = plistlib.readPlistFromString(pliststr)
        for entity in plist['system-entities']:
            if 'mount-point' in entity:
                mountpoints.append(entity['mount-point'])

    return mountpoints[0]


def unmountdmg(mountpoint):
    """
    Unmounts the dmg at mountpoint
    """
    proc = subprocess.Popen(['/usr/bin/hdiutil', 'detach', mountpoint],
                            bufsize=-1, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE)
    (dummy_output, err) = proc.communicate()
    if proc.returncode:
        print >> sys.stderr, 'Polite unmount failed: %s' % err
        print >> sys.stderr, 'Attempting to force unmount %s' % mountpoint
        # try forcing the unmount
        retcode = subprocess.call(['/usr/bin/hdiutil', 'detach', mountpoint,
                                   '-force'])
        if retcode:
            print >> sys.stderr, 'Failed to unmount %s' % mountpoint


def install_product(dist_path, target_vol):
    '''Install a product to a target volume.
    Returns a boolean to indicate success or failure.'''
    cmd = ['/usr/sbin/installer', '-pkg', dist_path, '-target', target_vol]
    try:
        subprocess.check_call(cmd)
        return True
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
        return False


class ReplicationError(Exception):
    '''A custom error when replication fails'''
    pass


def replicate_url(full_url, root_dir='/tmp',
                  show_progress=False, ignore_cache=False):
    '''Downloads a URL and stores it in the same relative path on our
    filesystem. Returns a path to the replicated file.'''

    path = urlparse.urlsplit(full_url)[2]
    relative_url = path.lstrip('/')
    relative_url = os.path.normpath(relative_url)
    local_file_path = os.path.join(root_dir, relative_url)
    if show_progress:
        options = '-fL'
    else:
        options = '-sfL'
    curl_cmd = ['/usr/bin/curl', options, '--create-dirs',
                '-o', local_file_path]
    if not ignore_cache and os.path.exists(local_file_path):
        curl_cmd.extend(['-z', local_file_path])
    curl_cmd.append(full_url)
    print "Downloading %s..." % full_url
    try:
        subprocess.check_call(curl_cmd)
    except subprocess.CalledProcessError, err:
        raise ReplicationError(err)
    return local_file_path


def parse_server_metadata(filename):
    '''Parses a softwareupdate server metadata file, looking for information
    of interest.
    Returns a dictionary containing title, version, and description.'''
    title = ''
    vers = ''
    try:
        md_plist = plistlib.readPlist(filename)
    except (OSError, IOError, ExpatError), err:
        print >> sys.stderr, 'Error reading %s: %s' % (filename, err)
        return {}
    vers = md_plist.get('CFBundleShortVersionString', '')
    localization = md_plist.get('localization', {})
    preferred_localization = (localization.get('English') or
                              localization.get('en'))
    if preferred_localization:
        title = preferred_localization.get('title', '')

    metadata = {}
    metadata['title'] = title
    metadata['version'] = vers
    return metadata


def get_server_metadata(catalog, product_key, workdir, ignore_cache=False):
    '''Replicate ServerMetaData'''
    try:
        url = catalog['Products'][product_key]['ServerMetadataURL']
        try:
            smd_path = replicate_url(
                url, root_dir=workdir, ignore_cache=ignore_cache)
            return smd_path
        except ReplicationError, err:
            print >> sys.stderr, (
                'Could not replicate %s: %s' % (url, err))
            return None
    except KeyError:
        print >> sys.stderr, 'Malformed catalog.'
        return None


def parse_dist(filename):
    '''Parses a softwareupdate dist file, returning a dict of info of
    interest'''
    dist_info = {}
    try:
        dom = minidom.parse(filename)
    except ExpatError:
        print >> sys.stderr, 'Invalid XML in %s' % filename
        return dist_info
    except IOError, err:
        print >> sys.stderr, 'Error reading %s: %s' % (filename, err)
        return dist_info

    auxinfos = dom.getElementsByTagName('auxinfo')
    if not auxinfos:
        return dist_info
    auxinfo = auxinfos[0]
    key = None
    value = None
    children = auxinfo.childNodes
    # handle the possibility that keys from auxinfo may be nested
    # within a 'dict' element
    dict_nodes = [n for n in auxinfo.childNodes
                  if n.nodeType == n.ELEMENT_NODE and
                  n.tagName == 'dict']
    if dict_nodes:
        children = dict_nodes[0].childNodes
    for node in children:
        if node.nodeType == node.ELEMENT_NODE and node.tagName == 'key':
            key = node.firstChild.wholeText
        if node.nodeType == node.ELEMENT_NODE and node.tagName == 'string':
            value = node.firstChild.wholeText
        if key and value:
            dist_info[key] = value
            key = None
            value = None
    return dist_info


def download_and_parse_sucatalog(sucatalog, workdir, ignore_cache=False):
    '''Downloads and returns a parsed softwareupdate catalog'''
    try:
        localcatalogpath = replicate_url(
            sucatalog, root_dir=workdir, ignore_cache=ignore_cache)
    except ReplicationError, err:
        print >> sys.stderr, 'Could not replicate %s: %s' % (sucatalog, err)
        exit(-1)
    try:
        catalog = plistlib.readPlist(localcatalogpath)
        return catalog
    except (OSError, IOError, ExpatError), err:
        print >> sys.stderr, (
            'Error reading %s: %s' % (localcatalogpath, err))
        exit(-1)


def find_mac_os_installers(catalog):
    '''Return a list of product identifiers for what appear to be macOS
    installers'''
    mac_os_installer_products = []
    if 'Products' in catalog:
        product_keys = list(catalog['Products'].keys())
        for product_key in product_keys:
            product = catalog['Products'][product_key]
            try:
                if product['ExtendedMetaInfo'][
                        'InstallAssistantPackageIdentifiers'][
                            'OSInstall'] == 'com.apple.mpkg.OSInstall':
                    mac_os_installer_products.append(product_key)
            except KeyError:
                continue
    return mac_os_installer_products


def os_installer_product_info(catalog, workdir, ignore_cache=False):
    '''Returns a dict of info about products that look like macOS installers'''
    product_info = {}
    installer_products = find_mac_os_installers(catalog)
    for product_key in installer_products:
        product_info[product_key] = {}
        filename = get_server_metadata(catalog, product_key, workdir)
        product_info[product_key] = parse_server_metadata(filename)
        product = catalog['Products'][product_key]
        product_info[product_key]['PostDate'] = str(product['PostDate'])
        distributions = product['Distributions']
        dist_url = distributions.get('English') or distributions.get('en')
        try:
            dist_path = replicate_url(
                dist_url, root_dir=workdir, ignore_cache=ignore_cache)
        except ReplicationError, err:
            print >> sys.stderr, 'Could not replicate %s: %s' % (dist_url, err)
        dist_info = parse_dist(dist_path)
        product_info[product_key]['DistributionPath'] = dist_path
        product_info[product_key].update(dist_info)

    return product_info


def replicate_product(catalog, product_id, workdir, ignore_cache=False):
    '''Downloads all the packages for a product'''
    product = catalog['Products'][product_id]
    for package in product.get('Packages', []):
        # TO-DO: Check 'Size' attribute and make sure
        # we have enough space on the target
        # filesystem before attempting to download
        if 'URL' in package:
            try:
                replicate_url(
                    package['URL'], root_dir=workdir,
                    show_progress=True, ignore_cache=ignore_cache)
            except ReplicationError, err:
                print >> sys.stderr, (
                    'Could not replicate %s: %s' % (package['URL'], err))
                exit(-1)
        if 'MetadataURL' in package:
            try:
                replicate_url(package['MetadataURL'], root_dir=workdir,
                              ignore_cache=ignore_cache)
            except ReplicationError, err:
                print >> sys.stderr, (
                    'Could not replicate %s: %s'
                    % (package['MetadataURL'], err))
                exit(-1)

def main():
    '''Do the main thing here'''

    if os.getuid() != 0:
        sys.exit('This command requires root (to install packages), so please '
                 'run again with sudo or as root.')

    parser = argparse.ArgumentParser()
    parser.add_argument('--catalogurl', metavar='sucatalog_url',
                        default=DEFAULT_SUCATALOG,
                        help='Software Update catalog URL.')
    parser.add_argument('--workdir', metavar='path_to_working_dir',
                        default='.',
                        help='Path to working directory on a volume with over '
                        '10G of available space. Defaults to current working '
                        'directory.')
    parser.add_argument('--compress', action='store_true',
                        help='Output a read-only compressed disk image with '
                        'the Install macOS app at the root.')
    parser.add_argument('--ignore-cache', action='store_true',
                        help='Ignore any previously cached files.')
    parser.add_argument('--build', metavar='build_version',
                        default='',
                        help='Specify a specific build to search for and '
                        'download.')
    parser.add_argument('--list', action='store_true',
                        help='Output the available updates to a plist '
                        'and quit.')
    args = parser.parse_args()

    # download sucatalog and look for products that are for macOS installers
    catalog = download_and_parse_sucatalog(
        args.catalogurl, args.workdir, ignore_cache=args.ignore_cache)
    product_info = os_installer_product_info(
        catalog, args.workdir, ignore_cache=args.ignore_cache)

    if not product_info:
        print >> sys.stderr, (
            'No macOS installer products found in the sucatalog.')
        exit(-1)

    output_plist = "%s/softwareupdate.plist" % args.workdir
    pl = {}
    pl['result'] = []

    # display a menu of choices (some seed catalogs have multiple installers)
    print '%2s %12s %10s %8s  %s' % ('#', 'ProductID', 'Version',
                                     'Build', 'Title')
    for index, product_id in enumerate(product_info):
        print '%2s %12s %10s %8s  %s' % (index+1,
                                         product_id,
                                         product_info[product_id]['version'],
                                         product_info[product_id]['BUILD'],
                                         product_info[product_id]['title'])

        pl_index =  {'index': index+1,
                'product_id': product_id,
                'version': product_info[product_id]['version'],
                'build': product_info[product_id]['BUILD'],
                'title': product_info[product_id]['title'],
                }

        pl['result'].append(pl_index)

        if args.build:
            if args.build == product_info[product_id]['BUILD']:
                answer = index+1


    # Output a plist of available updates and quit if --list option chosen
    if args.list:
        plistlib.writePlist(pl, output_plist)
        exit(0)

    # check for specified build if argument supplied
    if args.build:
        try:
            answer
        except NameError:
            print ('No valid build chosen. Run again without --build argument'
                   'to select a valid build to download.')
            exit(0)
        else:
            print '# %s chosen.' % answer
    else:
        answer = raw_input(
                '\nChoose a product to download (1-%s): ' % len(product_info))

    try:
        index = int(answer) - 1
        if index < 0:
            raise ValueError
        product_id = product_info.keys()[index]
    except (ValueError, IndexError):
        print 'Exiting.'
        exit(0)

    # download all the packages for the selected product
    replicate_product(
        catalog, product_id, args.workdir, ignore_cache=args.ignore_cache)

    # generate a name for the sparseimage
    volname = ('Install_macOS_%s-%s'
               % (product_info[product_id]['version'],
                  product_info[product_id]['BUILD']))
    sparse_diskimage_path = os.path.join(args.workdir, volname + '.sparseimage')
    if os.path.exists(sparse_diskimage_path):
        os.unlink(sparse_diskimage_path)

    # make an empty sparseimage and mount it
    print 'Making empty sparseimage...'
    sparse_diskimage_path = make_sparse_image(volname, sparse_diskimage_path)
    mountpoint = mountdmg(sparse_diskimage_path)
    if mountpoint:
        # install the product to the mounted sparseimage volume
        success = install_product(
            product_info[product_id]['DistributionPath'],
            mountpoint)
        if not success:
            print >> sys.stderr, 'Product installation failed.'
            unmountdmg(mountpoint)
            exit(-1)
        print 'Product downloaded and installed to %s' % sparse_diskimage_path
        if not args.compress:
            unmountdmg(mountpoint)
        else:
            # if --compress option given, create a r/o compressed diskimage
            # containing the Install macOS app
            compressed_diskimagepath = os.path.join(
                args.workdir, volname + '.dmg')
            if os.path.exists(compressed_diskimagepath):
                os.unlink(compressed_diskimagepath)
            applications_dir = os.path.join(mountpoint, 'Applications')
            for item in os.listdir(applications_dir):
                if item.endswith('.app'):
                    app_path = os.path.join(applications_dir, item)
                    make_compressed_dmg(app_path, compressed_diskimagepath)
                    break
            # unmount sparseimage
            unmountdmg(mountpoint)
            # delete sparseimage since we don't need it any longer
            os.unlink(sparse_diskimage_path)


if __name__ == '__main__':
    main()#!/usr/bin/python
# encoding: utf-8
#
# Copyright 2017 Greg Neagle.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Thanks to Tim Sutton for ideas, suggestions, and sample code.
#

'''installinstallmacos.py
A tool to download the parts for an Install macOS app from Apple's
softwareupdate servers and install a functioning Install macOS app onto an
empty disk image'''


import argparse
import os
import plistlib
import subprocess
import sys
import urlparse
from xml.dom import minidom
from xml.parsers.expat import ExpatError


DEFAULT_SUCATALOG = (
    'https://swscan.apple.com/content/catalogs/others/'
    'index-10.13seed-10.13-10.12-10.11-10.10-10.9'
    '-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog')


def make_sparse_image(volume_name, output_path):
    '''Make a sparse disk image we can install a product to'''
    cmd = ['/usr/bin/hdiutil', 'create', '-size', '8g', '-fs', 'HFS+',
           '-volname', volume_name, '-type', 'SPARSE', '-plist', output_path]
    try:
        output = subprocess.check_output(cmd)
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
        exit(-1)
    try:
        return plistlib.readPlistFromString(output)[0]
    except IndexError, err:
        print >> sys.stderr, 'Unexpected output from hdiutil: %s' % output
        exit(-1)
    except ExpatError, err:
        print >> sys.stderr, 'Malformed output from hdiutil: %s' % output
        print >> sys.stderr, err
        exit(-1)


def make_compressed_dmg(app_path, diskimagepath):
    """Returns path to newly-created compressed r/o disk image containing
    Install macOS.app"""

    print ('Making read-only compressed disk image containing %s...'
           % os.path.basename(app_path))
    cmd = ['/usr/bin/hdiutil', 'create', '-fs', 'HFS+',
           '-srcfolder', app_path, diskimagepath]
    try:
        subprocess.check_call(cmd)
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
    else:
        print 'Disk image created at: %s' % diskimagepath


def mountdmg(dmgpath):
    """
    Attempts to mount the dmg at dmgpath and returns first mountpoint
    """
    mountpoints = []
    dmgname = os.path.basename(dmgpath)
    cmd = ['/usr/bin/hdiutil', 'attach', dmgpath,
           '-mountRandom', '/tmp', '-nobrowse', '-plist',
           '-owners', 'on']
    proc = subprocess.Popen(cmd, bufsize=-1,
                            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    (pliststr, err) = proc.communicate()
    if proc.returncode:
        print >> sys.stderr, 'Error: "%s" while mounting %s.' % (err, dmgname)
        return None
    if pliststr:
        plist = plistlib.readPlistFromString(pliststr)
        for entity in plist['system-entities']:
            if 'mount-point' in entity:
                mountpoints.append(entity['mount-point'])

    return mountpoints[0]


def unmountdmg(mountpoint):
    """
    Unmounts the dmg at mountpoint
    """
    proc = subprocess.Popen(['/usr/bin/hdiutil', 'detach', mountpoint],
                            bufsize=-1, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE)
    (dummy_output, err) = proc.communicate()
    if proc.returncode:
        print >> sys.stderr, 'Polite unmount failed: %s' % err
        print >> sys.stderr, 'Attempting to force unmount %s' % mountpoint
        # try forcing the unmount
        retcode = subprocess.call(['/usr/bin/hdiutil', 'detach', mountpoint,
                                   '-force'])
        if retcode:
            print >> sys.stderr, 'Failed to unmount %s' % mountpoint


def install_product(dist_path, target_vol):
    '''Install a product to a target volume.
    Returns a boolean to indicate success or failure.'''
    cmd = ['/usr/sbin/installer', '-pkg', dist_path, '-target', target_vol]
    try:
        subprocess.check_call(cmd)
        return True
    except subprocess.CalledProcessError, err:
        print >> sys.stderr, err
        return False


class ReplicationError(Exception):
    '''A custom error when replication fails'''
    pass


def replicate_url(full_url, root_dir='/tmp',
                  show_progress=False, ignore_cache=False):
    '''Downloads a URL and stores it in the same relative path on our
    filesystem. Returns a path to the replicated file.'''

    path = urlparse.urlsplit(full_url)[2]
    relative_url = path.lstrip('/')
    relative_url = os.path.normpath(relative_url)
    local_file_path = os.path.join(root_dir, relative_url)
    if show_progress:
        options = '-fL'
    else:
        options = '-sfL'
    curl_cmd = ['/usr/bin/curl', options, '--create-dirs',
                '-o', local_file_path]
    if not ignore_cache and os.path.exists(local_file_path):
        curl_cmd.extend(['-z', local_file_path])
    curl_cmd.append(full_url)
    print "Downloading %s..." % full_url
    try:
        subprocess.check_call(curl_cmd)
    except subprocess.CalledProcessError, err:
        raise ReplicationError(err)
    return local_file_path


def parse_server_metadata(filename):
    '''Parses a softwareupdate server metadata file, looking for information
    of interest.
    Returns a dictionary containing title, version, and description.'''
    title = ''
    vers = ''
    try:
        md_plist = plistlib.readPlist(filename)
    except (OSError, IOError, ExpatError), err:
        print >> sys.stderr, 'Error reading %s: %s' % (filename, err)
        return {}
    vers = md_plist.get('CFBundleShortVersionString', '')
    localization = md_plist.get('localization', {})
    preferred_localization = (localization.get('English') or
                              localization.get('en'))
    if preferred_localization:
        title = preferred_localization.get('title', '')

    metadata = {}
    metadata['title'] = title
    metadata['version'] = vers
    return metadata


def get_server_metadata(catalog, product_key, workdir, ignore_cache=False):
    '''Replicate ServerMetaData'''
    try:
        url = catalog['Products'][product_key]['ServerMetadataURL']
        try:
            smd_path = replicate_url(
                url, root_dir=workdir, ignore_cache=ignore_cache)
            return smd_path
        except ReplicationError, err:
            print >> sys.stderr, (
                'Could not replicate %s: %s' % (url, err))
            return None
    except KeyError:
        print >> sys.stderr, 'Malformed catalog.'
        return None


def parse_dist(filename):
    '''Parses a softwareupdate dist file, returning a dict of info of
    interest'''
    dist_info = {}
    try:
        dom = minidom.parse(filename)
    except ExpatError:
        print >> sys.stderr, 'Invalid XML in %s' % filename
        return dist_info
    except IOError, err:
        print >> sys.stderr, 'Error reading %s: %s' % (filename, err)
        return dist_info

    auxinfos = dom.getElementsByTagName('auxinfo')
    if not auxinfos:
        return dist_info
    auxinfo = auxinfos[0]
    key = None
    value = None
    children = auxinfo.childNodes
    # handle the possibility that keys from auxinfo may be nested
    # within a 'dict' element
    dict_nodes = [n for n in auxinfo.childNodes
                  if n.nodeType == n.ELEMENT_NODE and
                  n.tagName == 'dict']
    if dict_nodes:
        children = dict_nodes[0].childNodes
    for node in children:
        if node.nodeType == node.ELEMENT_NODE and node.tagName == 'key':
            key = node.firstChild.wholeText
        if node.nodeType == node.ELEMENT_NODE and node.tagName == 'string':
            value = node.firstChild.wholeText
        if key and value:
            dist_info[key] = value
            key = None
            value = None
    return dist_info


def download_and_parse_sucatalog(sucatalog, workdir, ignore_cache=False):
    '''Downloads and returns a parsed softwareupdate catalog'''
    try:
        localcatalogpath = replicate_url(
            sucatalog, root_dir=workdir, ignore_cache=ignore_cache)
    except ReplicationError, err:
        print >> sys.stderr, 'Could not replicate %s: %s' % (sucatalog, err)
        exit(-1)
    try:
        catalog = plistlib.readPlist(localcatalogpath)
        return catalog
    except (OSError, IOError, ExpatError), err:
        print >> sys.stderr, (
            'Error reading %s: %s' % (localcatalogpath, err))
        exit(-1)


def find_mac_os_installers(catalog):
    '''Return a list of product identifiers for what appear to be macOS
    installers'''
    mac_os_installer_products = []
    if 'Products' in catalog:
        product_keys = list(catalog['Products'].keys())
        for product_key in product_keys:
            product = catalog['Products'][product_key]
            try:
                if product['ExtendedMetaInfo'][
                        'InstallAssistantPackageIdentifiers'][
                            'OSInstall'] == 'com.apple.mpkg.OSInstall':
                    mac_os_installer_products.append(product_key)
            except KeyError:
                continue
    return mac_os_installer_products


def os_installer_product_info(catalog, workdir, ignore_cache=False):
    '''Returns a dict of info about products that look like macOS installers'''
    product_info = {}
    installer_products = find_mac_os_installers(catalog)
    for product_key in installer_products:
        product_info[product_key] = {}
        filename = get_server_metadata(catalog, product_key, workdir)
        product_info[product_key] = parse_server_metadata(filename)
        product = catalog['Products'][product_key]
        product_info[product_key]['PostDate'] = str(product['PostDate'])
        distributions = product['Distributions']
        dist_url = distributions.get('English') or distributions.get('en')
        try:
            dist_path = replicate_url(
                dist_url, root_dir=workdir, ignore_cache=ignore_cache)
        except ReplicationError, err:
            print >> sys.stderr, 'Could not replicate %s: %s' % (dist_url, err)
        dist_info = parse_dist(dist_path)
        product_info[product_key]['DistributionPath'] = dist_path
        product_info[product_key].update(dist_info)

    return product_info


def replicate_product(catalog, product_id, workdir, ignore_cache=False):
    '''Downloads all the packages for a product'''
    product = catalog['Products'][product_id]
    for package in product.get('Packages', []):
        # TO-DO: Check 'Size' attribute and make sure
        # we have enough space on the target
        # filesystem before attempting to download
        if 'URL' in package:
            try:
                replicate_url(
                    package['URL'], root_dir=workdir,
                    show_progress=True, ignore_cache=ignore_cache)
            except ReplicationError, err:
                print >> sys.stderr, (
                    'Could not replicate %s: %s' % (package['URL'], err))
                exit(-1)
        if 'MetadataURL' in package:
            try:
                replicate_url(package['MetadataURL'], root_dir=workdir,
                              ignore_cache=ignore_cache)
            except ReplicationError, err:
                print >> sys.stderr, (
                    'Could not replicate %s: %s'
                    % (package['MetadataURL'], err))
                exit(-1)

def main():
    '''Do the main thing here'''

    if os.getuid() != 0:
        sys.exit('This command requires root (to install packages), so please '
                 'run again with sudo or as root.')

    parser = argparse.ArgumentParser()
    parser.add_argument('--catalogurl', metavar='sucatalog_url',
                        default=DEFAULT_SUCATALOG,
                        help='Software Update catalog URL.')
    parser.add_argument('--workdir', metavar='path_to_working_dir',
                        default='.',
                        help='Path to working directory on a volume with over '
                        '10G of available space. Defaults to current working '
                        'directory.')
    parser.add_argument('--compress', action='store_true',
                        help='Output a read-only compressed disk image with '
                        'the Install macOS app at the root.')
    parser.add_argument('--ignore-cache', action='store_true',
                        help='Ignore any previously cached files.')
    parser.add_argument('--build', metavar='build_version',
                        default='',
                        help='Specify a specific build to search for and '
                        'download.')
    parser.add_argument('--list', action='store_true',
                        help='Output the available updates to a plist '
                        'and quit.')
    args = parser.parse_args()

    # download sucatalog and look for products that are for macOS installers
    catalog = download_and_parse_sucatalog(
        args.catalogurl, args.workdir, ignore_cache=args.ignore_cache)
    product_info = os_installer_product_info(
        catalog, args.workdir, ignore_cache=args.ignore_cache)

    if not product_info:
        print >> sys.stderr, (
            'No macOS installer products found in the sucatalog.')
        exit(-1)

    output_plist = "%s/softwareupdate.plist" % args.workdir
    pl = {}
    pl['result'] = []

    # display a menu of choices (some seed catalogs have multiple installers)
    print '%2s %12s %10s %8s  %s' % ('#', 'ProductID', 'Version',
                                     'Build', 'Title')
    for index, product_id in enumerate(product_info):
        print '%2s %12s %10s %8s  %s' % (index+1,
                                         product_id,
                                         product_info[product_id]['version'],
                                         product_info[product_id]['BUILD'],
                                         product_info[product_id]['title'])

        pl_index =  {'index': index+1,
                'product_id': product_id,
                'version': product_info[product_id]['version'],
                'build': product_info[product_id]['BUILD'],
                'title': product_info[product_id]['title'],
                }

        pl['result'].append(pl_index)

        if args.build:
            if args.build == product_info[product_id]['BUILD']:
                answer = index+1


    # Output a plist of available updates and quit if --list option chosen
    if args.list:
        plistlib.writePlist(pl, output_plist)
        exit(0)

    # check for specified build if argument supplied
    if args.build:
        try:
            answer
        except NameError:
            print ('No valid build chosen. Run again without --build argument'
                   'to select a valid build to download.')
            exit(0)
        else:
            print '# %s chosen.' % answer
    else:
        answer = raw_input(
                '\nChoose a product to download (1-%s): ' % len(product_info))

    try:
        index = int(answer) - 1
        if index < 0:
            raise ValueError
        product_id = product_info.keys()[index]
    except (ValueError, IndexError):
        print 'Exiting.'
        exit(0)

    # download all the packages for the selected product
    replicate_product(
        catalog, product_id, args.workdir, ignore_cache=args.ignore_cache)

    # generate a name for the sparseimage
    volname = ('Install_macOS_%s-%s'
               % (product_info[product_id]['version'],
                  product_info[product_id]['BUILD']))
    sparse_diskimage_path = os.path.join(args.workdir, volname + '.sparseimage')
    if os.path.exists(sparse_diskimage_path):
        os.unlink(sparse_diskimage_path)

    # make an empty sparseimage and mount it
    print 'Making empty sparseimage...'
    sparse_diskimage_path = make_sparse_image(volname, sparse_diskimage_path)
    mountpoint = mountdmg(sparse_diskimage_path)
    if mountpoint:
        # install the product to the mounted sparseimage volume
        success = install_product(
            product_info[product_id]['DistributionPath'],
            mountpoint)
        if not success:
            print >> sys.stderr, 'Product installation failed.'
            unmountdmg(mountpoint)
            exit(-1)
        print 'Product downloaded and installed to %s' % sparse_diskimage_path
        if not args.compress:
            unmountdmg(mountpoint)
        else:
            # if --compress option given, create a r/o compressed diskimage
            # containing the Install macOS app
            compressed_diskimagepath = os.path.join(
                args.workdir, volname + '.dmg')
            if os.path.exists(compressed_diskimagepath):
                os.unlink(compressed_diskimagepath)
            applications_dir = os.path.join(mountpoint, 'Applications')
            for item in os.listdir(applications_dir):
                if item.endswith('.app'):
                    app_path = os.path.join(applications_dir, item)
                    make_compressed_dmg(app_path, compressed_diskimagepath)
                    break
            # unmount sparseimage
            unmountdmg(mountpoint)
            # delete sparseimage since we don't need it any longer
            os.unlink(sparse_diskimage_path)


if __name__ == '__main__':
    main()