zeroinstall/injector/reader.py

   1 """
   2 Parses an XML interface into a Python representation.
   3 """
   4
   5 # Copyright (C) 2006, Thomas Leonard
   6 # See the README file for details, or visit http://0install.net.
   7
   8 import os
   9 import sys
  10 import shutil
  11 import time
  12 from logging import debug, warn, info
  13 from os.path import dirname
  14
  15 from zeroinstall.support import basedir
  16 from zeroinstall.injector import qdom, distro
  17 from zeroinstall.injector.namespaces import *
  18 from zeroinstall.injector.model import *
  19 from zeroinstall.injector import model
  20 from zeroinstall import version, SafeException
  21
  22 def update_from_cache(interface):
  23         """Read a cached interface and any native feeds or user overrides.
  24         @param interface: the interface object to update
  25         @type interface: L{model.Interface}
  26         @return: True if cached version and user overrides loaded OK.
  27         False if upstream not cached. Local interfaces (starting with /) are
  28         always considered to be cached, although they are not actually stored in the cache.
  29         @rtype: bool"""
  30         interface.reset()
  31         main_feed = None
  32
  33         if interface.uri.startswith('/'):
  34                 debug("Loading local interface file '%s'", interface.uri)
  35                 update(interface, interface.uri, local = True)
  36                 cached = True
  37         else:
  38                 cached = basedir.load_first_cache(config_site, 'interfaces', escape(interface.uri))
  39                 if cached:
  40                         debug("Loading cached information for %s from %s", interface, cached)
  41                         main_feed = update(interface, cached)
  42
  43         # Add the distribution package manager's version, if any
  44         path = basedir.load_first_data(config_site, 'native_feeds', model._pretty_escape(interface.uri))
  45         if path:
  46                 # Resolve any symlinks
  47                 info("Adding native packager feed '%s'", path)
  48                 interface.extra_feeds.append(Feed(os.path.realpath(path), None, False))
  49
  50         update_user_overrides(interface, main_feed)
  51
  52         # Special case: add our fall-back local copy of the injector as a feed
  53         if interface.uri == injector_gui_uri:
  54                 local_gui = os.path.join(os.path.abspath(dirname(dirname(__file__))), '0launch-gui', 'ZeroInstall-GUI.xml')
  55                 interface.extra_feeds.append(Feed(local_gui, None, False))
  56
  57         return bool(cached)
  58
  59 def update_user_overrides(interface, main_feed = None):
  60         """Update an interface with user-supplied information.
  61         @param interface: the interface object to update
  62         @type interface: L{model.Interface}
  63         @param main_feed: feed to update with last_checked information
  64         @note: feed updates shouldn't really be here. main_feed may go away in future.
  65         """
  66         user = basedir.load_first_config(config_site, config_prog,
  67                                            'user_overrides', escape(interface.uri))
  68         if not user:
  69                 return
  70
  71         root = qdom.parse(file(user))
  72
  73         # This is a bit wrong; this information is about the feed,
  74         # not the interface.
  75         if main_feed:
  76                 last_checked = root.getAttribute('last-checked')
  77                 if last_checked:
  78                         main_feed.last_checked = int(last_checked)
  79
  80         stability_policy = root.getAttribute('stability-policy')
  81         if stability_policy:
  82                 interface.set_stability_policy(stability_levels[str(stability_policy)])
  83
  84         for item in root.childNodes:
  85                 if item.uri != XMLNS_IFACE: continue
  86                 if item.name == 'implementation':
  87                         id = item.getAttribute('id')
  88                         assert id is not None
  89                         if not (id.startswith('/') or id.startswith('.') or id.startswith('package:')):
  90                                 assert '=' in id
  91                         impl = interface.implementations.get(id, None)
  92                         if not impl:
  93                                 debug("Ignoring user-override for unknown implementation %s in %s", id, interface)
  94                                 continue
  95
  96                         user_stability = item.getAttribute('user-stability')
  97                         if user_stability:
  98                                 impl.user_stability = stability_levels[str(user_stability)]
  99                 elif item.name == 'feed':
 100                         feed_src = item.getAttribute('src')
 101                         if not feed_src:
 102                                 raise InvalidInterface('Missing "src" attribute in <feed>')
 103                         interface.extra_feeds.append(Feed(feed_src, item.getAttribute('arch'), True, langs = item.getAttribute('langs')))
 104
 105 def check_readable(interface_uri, source):
 106         """Test whether an interface file is valid.
 107         @param interface_uri: the interface's URI
 108         @type interface_uri: str
 109         @param source: the name of the file to test
 110         @type source: str
 111         @return: the modification time in src (usually just the mtime of the file)
 112         @rtype: int
 113         @raise InvalidInterface: If the source's syntax is incorrect,
 114         """
 115         tmp = Interface(interface_uri)
 116         try:
 117                 update(tmp, source)
 118         except InvalidInterface, ex:
 119                 info("Error loading feed:\n"
 120                         "Interface URI: %s\n"
 121                         "Local file: %s\n%s" %
 122                         (interface_uri, source, ex))
 123                 raise InvalidInterface("Error loading feed '%s':\n\n%s" % (interface_uri, ex))
 124         return tmp.last_modified
 125
 126 def update(interface, source, local = False):
 127         """Read in information about an interface.
 128         @param interface: the interface object to update
 129         @type interface: L{model.Interface}
 130         @param source: the name of the file to read
 131         @type source: str
 132         @param local: use file's mtime for last-modified, and uri attribute is ignored
 133         @raise InvalidInterface: if the source's syntax is incorrect
 134         @return: the new feed (since 0.32)
 135         @see: L{update_from_cache}, which calls this"""
 136         assert isinstance(interface, Interface)
 137
 138         try:
 139                 root = qdom.parse(file(source))
 140         except IOError, ex:
 141                 if ex.errno == 2:
 142                         raise InvalidInterface("Feed not found. Perhaps this is a local feed that no longer exists? You can remove it from the list of feeds in that case.", ex)
 143                 raise InvalidInterface("Can't read file", ex)
 144         except Exception, ex:
 145                 raise InvalidInterface("Invalid XML", ex)
 146
 147         if local:
 148                 local_path = source
 149         else:
 150                 local_path = None
 151         feed = ZeroInstallFeed(root, local_path, distro.get_host_distribution())
 152         feed.last_modified = int(os.stat(source).st_mtime)
 153
 154         if not local:
 155                 if feed.url != interface.uri:
 156                         raise InvalidInterface("Incorrect URL used for feed.\n\n"
 157                                                 "%s is given in the feed, but\n"
 158                                                 "%s was requested" %
 159                                                 (feed.url, interface.uri))
 160
 161         interface._main_feed = feed
 162         return feed