Cygwin Setup Updater v1.0

# Released under the GNU General Public License version 3 by J2897.
import os
title = 'Cygwin Setup Updater'
os.system('title ' + title)
drive_letter = os.getenv('SYSTEMDRIVE')
tmp = os.getenv('TEMP')
userprofile = os.getenv('USERPROFILE')
pickle_cache = userprofile + '\\Cygwin.dat'
cygstore = drive_letter + '\\cygstore'
def stop():
    import sys
    sys.exit()
target = 'most recent version'
url = 'https://www.cygwin.com'
print 'Main target:         ' + target
print 'URL:             ' + url

# Get the web-page.
def get_page(page):
    import urllib2
    source = urllib2.urlopen(page)
    return source.read()
try:
    page = get_page(url)
except:
    print 'Could not download the page. You may not be connected to the internet.'
    stop()

# Get the current version information from the web-page.
def find_site_ver(page):
    A1 = page.find(target)
    if A1 == -1:
        return None, None, None
    A2 = page.find('>', A1+len(target))
    A3 = page.find('<', A2)
    site_ver = page[A2+1:A3]
    second_target = 'href="'
    B1 = page.find(second_target, A2) + len(second_target)
    B2 = page.find('"', B1)
    filename_32 = page[B1:B2]
    third_target = 'href="'
    C1 = page.find(third_target, B2) + len(third_target)
    C2 = page.find('"', C1)
    filename_64 = page[C1:C2]
    return filename_32, filename_64, site_ver # setup-x86.exe setup-x86_64.exe 2.3.0
try:
    site_filename_32, site_filename_64, site_ver = find_site_ver(page)
except:
    print 'Could not search the page.'
    stop()
if site_filename_32 == None:
    print 'The search target has not been found on the page. The formatting, or the text on the page, may have been changed.'
    stop()

# Detect the OS architecture.
def get_os_architecture():
    PA, PAW6432 = os.getenv('PROCESSOR_ARCHITECTURE'), os.getenv('PROCESSOR_ARCHITEW6432')
    if (PA == 'x86' and PAW6432 == None):
        return '32-Bit'
    else:
        return '64-Bit'
bit = get_os_architecture()

# Select the appropriate setup file.
if bit == '64-Bit':
    site_filename = site_filename_64
else:
    site_filename = site_filename_32
print 'Found ' + bit + ' setup file:    ' + site_filename
print 'Site version:            ' + site_ver

# Is the cache file in the user's profile folder?
import cPickle
if not os.path.isdir(cygstore):
    print 'Creating folder:         ' + cygstore
    os.makedirs(cygstore)
elif os.path.isfile(pickle_cache):

    # Get the version information from the cache file (e.g. '2.2.0').
    def load_pickle_file():
        with open(pickle_cache, 'rb') as pickle_file:
            return cPickle.load(pickle_file)
    try:
        local_ver = load_pickle_file()
        print 'Local version:           ' + local_ver
    except:
        print 'Could not load cache.'
        stop()

    # Is the local version the same as the site version?
    if local_ver == site_ver:
        print 'Match!'
        stop()

# Download the setup file.
try:
    import urllib
    urllib.urlretrieve(url + '/' + site_filename, tmp + '\\' + site_filename)
    if os.path.isfile(cygstore + '\\' + site_filename):
        os.remove(cygstore + '\\' + site_filename)
    os.rename(tmp + '\\' + site_filename, cygstore + '\\' + site_filename)
except:
    print 'Could not download the file.'
    stop()
else:
    print 'Downloaded.'

# Dump the site version information into the cache file.
def dump_pickle_file(cache_file, version):
    with open(cache_file, 'wb') as pickle_file:
        cPickle.dump(version, pickle_file)
try:
    dump_pickle_file(pickle_cache, site_ver)
except:
    print 'Could not dump the site version information to: ' + pickle_cache
    stop()
else:
    print 'Dumped cache:        ' + pickle_cache