zeroinstall/injector/reader.py

   1 """
   2 Parses an XML interface into a Python representation.
   3 """
   4
   5 # Copyright (C) 2009, Thomas Leonard
   6 # See the README file for details, or visit http://0install.net.
   7
   8 from zeroinstall import _
   9 import os
  10 from logging import debug, info, warn
  11
  12 from zeroinstall.support import basedir
  13 from zeroinstall.injector import qdom, distro
  14 from zeroinstall.injector.namespaces import config_site, config_prog, XMLNS_IFACE
  15 from zeroinstall.injector.model import Interface, InvalidInterface, ZeroInstallFeed, escape, Feed, stability_levels
  16 from zeroinstall.injector import model
  17
  18 def update_from_cache(interface):
  19         """Read a cached interface and any native feeds or user overrides.
  20         @param interface: the interface object to update
  21         @type interface: L{model.Interface}
  22         @return: True if cached version and user overrides loaded OK.
  23         False if upstream not cached. Local interfaces (starting with /) are
  24         always considered to be cached, although they are not actually stored in the cache.
  25         @rtype: bool"""
  26         interface.reset()
  27         from zeroinstall.injector.iface_cache import iface_cache
  28         main_feed = iface_cache.get_feed(interface.uri, force = True)
  29
  30         # Add the distribution package manager's version, if any
  31         path = basedir.load_first_data(config_site, 'native_feeds', model._pretty_escape(interface.uri))
  32         if path:
  33                 # Resolve any symlinks
  34                 info(_("Adding native packager feed '%s'"), path)
  35                 interface.extra_feeds.append(Feed(os.path.realpath(path), None, False))
  36
  37         update_user_overrides(interface, main_feed)
  38
  39         return main_feed is not None
  40
  41 def load_feed_from_cache(url):
  42         """Load a feed. If the feed is remote, load from the cache. If local, load it directly.
  43         @return the feed, or None if it's remote and not cached."""
  44         if url.startswith('/'):
  45                 debug(_("Loading local feed file '%s'"), url)
  46                 return load_feed(url, local = True)
  47         else:
  48                 cached = basedir.load_first_cache(config_site, 'interfaces', escape(url))
  49                 if cached:
  50                         debug(_("Loading cached information for %(interface)s from %(cached)s"), {'interface': url, 'cached': cached})
  51                         return load_feed(cached, local = False)
  52                 else:
  53                         return None
  54
  55 def update_user_overrides(interface, main_feed = None):
  56         """Update an interface with user-supplied information.
  57         @param interface: the interface object to update
  58         @type interface: L{model.Interface}
  59         @param main_feed: feed to update with last_checked information
  60         @note: feed updates shouldn't really be here. main_feed may go away in future.
  61         """
  62         user = basedir.load_first_config(config_site, config_prog,
  63                                            'user_overrides', escape(interface.uri))
  64         if not user:
  65                 return
  66
  67         try:
  68                 root = qdom.parse(file(user))
  69         except Exception, ex:
  70                 warn(_("Error reading '%(user)s': %(exception)s"), {'user': user, 'exception': ex})
  71                 raise
  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                         if main_feed:
  92                                 impl = main_feed.implementations.get(id, None)
  93                         else:
  94                                 impl = None
  95                         if not impl:
  96                                 debug(_("Ignoring user-override for unknown implementation %(id)s in %(interface)s"), {'id': id, 'interface': interface})
  97                                 continue
  98
  99                         user_stability = item.getAttribute('user-stability')
 100                         if user_stability:
 101                                 impl.user_stability = stability_levels[str(user_stability)]
 102                 elif item.name == 'feed':
 103                         feed_src = item.getAttribute('src')
 104                         if not feed_src:
 105                                 raise InvalidInterface(_('Missing "src" attribute in <feed>'))
 106                         interface.extra_feeds.append(Feed(feed_src, item.getAttribute('arch'), True, langs = item.getAttribute('langs')))
 107
 108 def check_readable(feed_url, source):
 109         """Test whether a feed file is valid.
 110         @param feed_url: the feed's expected URL
 111         @type feed_url: str
 112         @param source: the name of the file to test
 113         @type source: str
 114         @return: the modification time in src (usually just the mtime of the file)
 115         @rtype: int
 116         @raise InvalidInterface: If the source's syntax is incorrect,
 117         """
 118         try:
 119                 feed = load_feed(source, local = False)
 120
 121                 if feed.url != feed_url:
 122                         raise InvalidInterface(_("Incorrect URL used for feed.\n\n"
 123                                                 "%(feed_url)s is given in the feed, but\n"
 124                                                 "%(interface_uri)s was requested") %
 125                                                 {'feed_url': feed.url, 'interface_uri': feed_url})
 126                 return feed.last_modified
 127         except InvalidInterface, ex:
 128                 info(_("Error loading feed:\n"
 129                         "Interface URI: %(uri)s\n"
 130                         "Local file: %(source)s\n"
 131                         "%(exception)s") %
 132                         {'uri': feed_url, 'source': source, 'exception': ex})
 133                 raise InvalidInterface(_("Error loading feed '%(uri)s':\n\n%(exception)s") % {'uri': feed_url, 'exception': ex})
 134
 135 def update(interface, source, local = False):
 136         """Read in information about an interface.
 137         Deprecated.
 138         @param interface: the interface object to update
 139         @type interface: L{model.Interface}
 140         @param source: the name of the file to read
 141         @type source: str
 142         @param local: use file's mtime for last-modified, and uri attribute is ignored
 143         @raise InvalidInterface: if the source's syntax is incorrect
 144         @return: the new feed (since 0.32)
 145         @see: L{update_from_cache}, which calls this"""
 146         assert isinstance(interface, Interface)
 147
 148         feed = load_feed(source, local)
 149
 150         if not local:
 151                 if feed.url != interface.uri:
 152                         raise InvalidInterface(_("Incorrect URL used for feed.\n\n"
 153                                                 "%(feed_url)s is given in the feed, but\n"
 154                                                 "%(interface_uri)s was requested") %
 155                                                 {'feed_url': feed.url, 'interface_uri': interface.uri})
 156
 157         # Hack.
 158         from zeroinstall.injector.iface_cache import iface_cache
 159         iface_cache._feeds[unicode(interface.uri)] = feed
 160
 161         return feed
 162
 163 def load_feed(source, local = False):
 164         """Load a feed from a local file.
 165         @param source: the name of the file to read
 166         @type source: str
 167         @param local: this is a local feed
 168         @type local: bool
 169         @raise InvalidInterface: if the source's syntax is incorrect
 170         @return: the new feed
 171         @since: 0.48
 172         @see: L{iface_cache.get_feed}, which calls this"""
 173         try:
 174                 root = qdom.parse(file(source))
 175         except IOError, ex:
 176                 if ex.errno == 2:
 177                         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)
 178                 raise InvalidInterface(_("Can't read file"), ex)
 179         except Exception, ex:
 180                 raise InvalidInterface(_("Invalid XML"), ex)
 181
 182         if local:
 183                 local_path = source
 184         else:
 185                 local_path = None
 186         feed = ZeroInstallFeed(root, local_path, distro.get_host_distribution())
 187         feed.last_modified = int(os.stat(source).st_mtime)
 188         return feed