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