zeroinstall/injector/reader.py

   1 """
   2 Parses an XML feed into a Python representation. You should probably use L{iface_cache.iface_cache} rather than the functions here.
   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
  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, iface_cache = None):
  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         Internal: use L{iface_cache.IfaceCache.get_interface} instread.
  26         @rtype: bool"""
  27         interface.reset()
  28         if iface_cache is None:
  29                 from zeroinstall.injector import policy
  30                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
  31
  32         # Add the distribution package manager's version, if any
  33         path = basedir.load_first_data(config_site, 'native_feeds', model._pretty_escape(interface.uri))
  34         if path:
  35                 # Resolve any symlinks
  36                 info(_("Adding native packager feed '%s'"), path)
  37                 interface.extra_feeds.append(Feed(os.path.realpath(path), None, False))
  38
  39         update_user_overrides(interface)
  40
  41         main_feed = iface_cache.get_feed(interface.uri, force = True)
  42         if main_feed:
  43                 update_user_feed_overrides(main_feed)
  44
  45         return main_feed is not None
  46
  47 def load_feed_from_cache(url, selections_ok = False):
  48         """Load a feed. If the feed is remote, load from the cache. If local, load it directly.
  49         @return: the feed, or None if it's remote and not cached."""
  50         try:
  51                 if os.path.isabs(url):
  52                         debug(_("Loading local feed file '%s'"), url)
  53                         return load_feed(url, local = True, selections_ok = selections_ok)
  54                 else:
  55                         cached = basedir.load_first_cache(config_site, 'interfaces', escape(url))
  56                         if cached:
  57                                 debug(_("Loading cached information for %(interface)s from %(cached)s"), {'interface': url, 'cached': cached})
  58                                 return load_feed(cached, local = False)
  59                         else:
  60                                 return None
  61         except InvalidInterface, ex:
  62                 ex.feed_url = url
  63                 raise
  64
  65 def update_user_feed_overrides(feed):
  66         """Update a feed with user-supplied information.
  67         Sets last_checked and user_stability ratings.
  68         @param feed: feed to update
  69         @since 0.49
  70         """
  71         user = basedir.load_first_config(config_site, config_prog,
  72                                            'feeds', model._pretty_escape(feed.url))
  73         if user is None:
  74                 # For files saved by 0launch < 0.49
  75                 user = basedir.load_first_config(config_site, config_prog,
  76                                                    'user_overrides', escape(feed.url))
  77         if not user:
  78                 return
  79
  80         try:
  81                 root = qdom.parse(file(user))
  82         except Exception, ex:
  83                 warn(_("Error reading '%(user)s': %(exception)s"), {'user': user, 'exception': ex})
  84                 raise
  85
  86         last_checked = root.getAttribute('last-checked')
  87         if last_checked:
  88                 feed.last_checked = int(last_checked)
  89
  90         for item in root.childNodes:
  91                 if item.uri != XMLNS_IFACE: continue
  92                 if item.name == 'implementation':
  93                         id = item.getAttribute('id')
  94                         assert id is not None
  95                         impl = feed.implementations.get(id, None)
  96                         if not impl:
  97                                 debug(_("Ignoring user-override for unknown implementation %(id)s in %(interface)s"), {'id': id, 'interface': feed})
  98                                 continue
  99
 100                         user_stability = item.getAttribute('user-stability')
 101                         if user_stability:
 102                                 impl.user_stability = stability_levels[str(user_stability)]
 103
 104 def update_user_overrides(interface):
 105         """Update an interface with user-supplied information.
 106         Sets preferred stability and updates extra_feeds.
 107         @param interface: the interface object to update
 108         @type interface: L{model.Interface}
 109         """
 110         user = basedir.load_first_config(config_site, config_prog,
 111                                            'interfaces', model._pretty_escape(interface.uri))
 112         if user is None:
 113                 # For files saved by 0launch < 0.49
 114                 user = basedir.load_first_config(config_site, config_prog,
 115                                                    'user_overrides', escape(interface.uri))
 116         if not user:
 117                 return
 118
 119         try:
 120                 root = qdom.parse(file(user))
 121         except Exception, ex:
 122                 warn(_("Error reading '%(user)s': %(exception)s"), {'user': user, 'exception': ex})
 123                 raise
 124
 125         stability_policy = root.getAttribute('stability-policy')
 126         if stability_policy:
 127                 interface.set_stability_policy(stability_levels[str(stability_policy)])
 128
 129         for item in root.childNodes:
 130                 if item.uri != XMLNS_IFACE: continue
 131                 if item.name == 'feed':
 132                         feed_src = item.getAttribute('src')
 133                         if not feed_src:
 134                                 raise InvalidInterface(_('Missing "src" attribute in <feed>'))
 135                         interface.extra_feeds.append(Feed(feed_src, item.getAttribute('arch'), True, langs = item.getAttribute('langs')))
 136
 137 def check_readable(feed_url, source):
 138         """Test whether a feed file is valid.
 139         @param feed_url: the feed's expected URL
 140         @type feed_url: str
 141         @param source: the name of the file to test
 142         @type source: str
 143         @return: the modification time in src (usually just the mtime of the file)
 144         @rtype: int
 145         @raise InvalidInterface: If the source's syntax is incorrect,
 146         """
 147         try:
 148                 feed = load_feed(source, local = False)
 149
 150                 if feed.url != feed_url:
 151                         raise InvalidInterface(_("Incorrect URL used for feed.\n\n"
 152                                                 "%(feed_url)s is given in the feed, but\n"
 153                                                 "%(interface_uri)s was requested") %
 154                                                 {'feed_url': feed.url, 'interface_uri': feed_url})
 155                 return feed.last_modified
 156         except InvalidInterface, ex:
 157                 info(_("Error loading feed:\n"
 158                         "Interface URI: %(uri)s\n"
 159                         "Local file: %(source)s\n"
 160                         "%(exception)s") %
 161                         {'uri': feed_url, 'source': source, 'exception': ex})
 162                 raise InvalidInterface(_("Error loading feed '%(uri)s':\n\n%(exception)s") % {'uri': feed_url, 'exception': ex})
 163
 164 def update(interface, source, local = False, iface_cache = None):
 165         """Read in information about an interface.
 166         Deprecated.
 167         @param interface: the interface object to update
 168         @type interface: L{model.Interface}
 169         @param source: the name of the file to read
 170         @type source: str
 171         @param local: use file's mtime for last-modified, and uri attribute is ignored
 172         @raise InvalidInterface: if the source's syntax is incorrect
 173         @return: the new feed (since 0.32)
 174         @see: L{update_from_cache}, which calls this"""
 175         assert isinstance(interface, Interface)
 176
 177         feed = load_feed(source, local)
 178
 179         if not local:
 180                 if feed.url != interface.uri:
 181                         raise InvalidInterface(_("Incorrect URL used for feed.\n\n"
 182                                                 "%(feed_url)s is given in the feed, but\n"
 183                                                 "%(interface_uri)s was requested") %
 184                                                 {'feed_url': feed.url, 'interface_uri': interface.uri})
 185
 186         if iface_cache is None:
 187                 from zeroinstall.injector import policy
 188                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
 189         iface_cache._feeds[unicode(interface.uri)] = feed
 190
 191         return feed
 192
 193 def load_feed(source, local = False, selections_ok = False):
 194         """Load a feed from a local file.
 195         @param source: the name of the file to read
 196         @type source: str
 197         @param local: this is a local feed
 198         @type local: bool
 199         @param selections_ok: if it turns out to be a local selections document, return that instead
 200         @type selections_ok: bool
 201         @raise InvalidInterface: if the source's syntax is incorrect
 202         @return: the new feed
 203         @since: 0.48
 204         @see: L{iface_cache.iface_cache}, which uses this to load the feeds"""
 205         try:
 206                 root = qdom.parse(file(source))
 207         except IOError, ex:
 208                 if ex.errno == 2:
 209                         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)
 210                 raise InvalidInterface(_("Can't read file"), ex)
 211         except Exception, ex:
 212                 raise InvalidInterface(_("Invalid XML"), ex)
 213
 214         if local:
 215                 if selections_ok and root.uri == XMLNS_IFACE and root.name == 'selections':
 216                         from zeroinstall.injector import selections
 217                         return selections.Selections(root)
 218                 local_path = source
 219         else:
 220                 local_path = None
 221         feed = ZeroInstallFeed(root, local_path)
 222         feed.last_modified = int(os.stat(source).st_mtime)
 223         return feed