simple addon installer prototype1

#!/usr/bin/python
import xml.dom.minidom
import os, sys, tarfile, urllib, hashlib, ctypes


ADDON_DIR = '/tmp'
if len(sys.argv) > 2: ADDON_DIR = sys.argv[-1]
print('addon path', ADDON_DIR )

IS32BIT = (ctypes.sizeof(ctypes.c_void_p)==4)   #http://stackoverflow.com/questions/1405913/how-do-i-determine-if-my-python-shell-is-executing-in-32bit-or-64bit-mode
_linux_types = 'ubuntu debian fedora suse maemo'.split()
def _guess_subplatform():
    if os.name == 'posix':
        sysname, nodename, release, version, machine = os.uname()
        for linuxtype in _linux_types:
            if linuxtype in version.lower(): return linuxtype
        return 'ubuntu' # default to ubuntu
    return ''


def download( url, md5=None, path='' ):
    print('downloading', url )
    assert not path.startswith('../')   # do not allow outside of REXADDONS
    data = urllib.urlopen( url ).read()
    if md5: assert hashlib.md5sum( data ).hexdigest() == md5
    tmp = '/tmp/%s' %os.path.split( url )[-1]
    f = open( tmp, 'wb' ); f.write( data ); f.close()
    if url.endswith('.tar.gz') or url.endswith('.tgz') or url.endswith('.tar.bz2') or url.endswith('.tar'):
        print( 'untarring', tmp )
        tar = tarfile.TarFile.open( tmp, 'r:*' )
        fpath = os.path.join(ADDON_DIR,path)
        if not os.path.isdir(fpath): os.makedirs( fpath )
        print( 'extracting to:', fpath )
        tar.extractall( path=fpath )

def install_addon( url, PATH='/tmp/addontest' ):
    doc = xml.dom.minidom.parse( url )
    platforms = doc.documentElement.getAttribute('platforms')
    if not platforms: print('warning: this addon did not describe what platforms it can run on')
    elif platforms == 'all': print('addon runs on all platforms')
    else:
        print('addon only supports the following platforms:')
        for plat in platforms.split(','): print( plat )

    ## extract simple archives ##
    for ar in doc.getElementsByTagName('archive'):
        url = ar.getAttribute('url')
        download( url, md5=ar.getAttribute('md5'), path=ar.getAttribute('path') )

    for library in doc.getElementsByTagName('library'):
        libs = []
        if sys.platform == 'linux2':
            for lib in library.getElementsByTagName('linux'):
                if IS32BIT and lib.getAttribute('bits')=='32': libs.append( lib )
                elif not IS32BIT and lib.getAttribute('bits')=='64': libs.append( lib )
        elif sys.platform.startswith('win'):
            for lib in library.getElementsByTagName('windows'):
                if IS32BIT and lib.getAttribute('bits')=='32': libs.append( lib )
                elif not IS32BIT and lib.getAttribute('bits')=='64': libs.append( lib )
        elif sys.platform == 'darwin':
            for lib in library.getElementsByTagName('osx'):
                if IS32BIT and lib.getAttribute('bits')=='32': libs.append( lib )
                elif not IS32BIT and lib.getAttribute('bits')=='64': libs.append( lib )

        if not libs:
            if library.getAttribute('required')=='True': print('error: this library is required %s' %library.getAttribute('name'))
            print('no precompiled library for your OS')
            sources = library.getElementsByTagName('source')
            for src in sources:
                print('source is available here:')
                print( src.getAttribute('url') )
                print( src.getAttribute('notes') )

        for lib in libs:
            url = lib.getAttribute('url')
            download( url, md5=lib.getAttribute('md5'), path=lib.getAttribute('path') )

    configs = {}
    for cfg in doc.getElementsByTagName('config'):  # embeded config files
        name = cfg.getAttribute('name')
        assert name
        configs[ name ] = cfg.firstChild.nodeValue  # must be a text node
        open( os.path.join( ADDON_DIR, name ), 'wb' ).write( cfg.firstChild.nodeValue )

    print configs
    return configs  # installer-manager needs to keep track of ini-files to enable/disable the addon


if __name__ == '__main__':
    install_addon( sys.argv[1] )