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         main_feed = None
  28
  29         if interface.uri.startswith('/'):
  30                 debug(_("Loading local interface file '%s'"), interface.uri)
  31                 update(interface, interface.uri, local = True)
  32                 cached = True
  33         else:
  34                 cached = basedir.load_first_cache(config_site, 'interfaces', escape(interface.uri))
  35                 if cached:
  36                         debug(_("Loading cached information for %(interface)s from %(cached)s"), {'interface': interface, 'cached': cached})
  37                         main_feed = update(interface, cached)
  38
  39         # Add the distribution package manager's version, if any
  40         path = basedir.load_first_data(config_site, 'native_feeds', model._pretty_escape(interface.uri))
  41         if path:
  42                 # Resolve any symlinks
  43                 info(_("Adding native packager feed '%s'"), path)
  44                 interface.extra_feeds.append(Feed(os.path.realpath(path), None, False))
  45
  46         update_user_overrides(interface, main_feed)
  47
  48         return bool(cached)
  49
  50 def update_user_overrides(interface, main_feed = None):
  51         """Update an interface with user-supplied information.
  52         @param interface: the interface object to update
  53         @type interface: L{model.Interface}
  54         @param main_feed: feed to update with last_checked information
  55         @note: feed updates shouldn't really be here. main_feed may go away in future.
  56         """
  57         user = basedir.load_first_config(config_site, config_prog,
  58                                            'user_overrides', escape(interface.uri))
  59         if not user:
  60                 return
  61
  62         try:
  63                 root = qdom.parse(file(user))
  64         except Exception, ex:
  65                 warn(_("Error reading '%(user)s': %(exception)s"), {'user': user, 'exception': ex})
  66                 raise
  67
  68         # This is a bit wrong; this information is about the feed,
  69         # not the interface.
  70         if main_feed:
  71                 last_checked = root.getAttribute('last-checked')
  72                 if last_checked:
  73                         main_feed.last_checked = int(last_checked)
  74
  75         stability_policy = root.getAttribute('stability-policy')
  76         if stability_policy:
  77                 interface.set_stability_policy(stability_levels[str(stability_policy)])
  78
  79         for item in root.childNodes:
  80                 if item.uri != XMLNS_IFACE: continue
  81                 if item.name == 'implementation':
  82                         id = item.getAttribute('id')
  83                         assert id is not None
  84                         if not (id.startswith('/') or id.startswith('.') or id.startswith('package:')):
  85                                 assert '=' in id
  86                         impl = interface.implementations.get(id, None)
  87                         if not impl:
  88                                 debug(_("Ignoring user-override for unknown implementation %(id)s in %(interface)s"), {'id': id, 'interface': interface})
  89                                 continue
  90
  91                         user_stability = item.getAttribute('user-stability')
  92                         if user_stability:
  93                                 impl.user_stability = stability_levels[str(user_stability)]
  94                 elif item.name == 'feed':
  95                         feed_src = item.getAttribute('src')
  96                         if not feed_src:
  97                                 raise InvalidInterface(_('Missing "src" attribute in <feed>'))
  98                         interface.extra_feeds.append(Feed(feed_src, item.getAttribute('arch'), True, langs = item.getAttribute('langs')))
  99
 100 def check_readable(interface_uri, source):
 101         """Test whether an interface file is valid.
 102         @param interface_uri: the interface's URI
 103         @type interface_uri: str
 104         @param source: the name of the file to test
 105         @type source: str
 106         @return: the modification time in src (usually just the mtime of the file)
 107         @rtype: int
 108         @raise InvalidInterface: If the source's syntax is incorrect,
 109         """
 110         tmp = Interface(interface_uri)
 111         try:
 112                 update(tmp, source)
 113         except InvalidInterface, ex:
 114                 info(_("Error loading feed:\n"
 115                         "Interface URI: %(uri)s\n"
 116                         "Local file: %(source)s\n"
 117                         "%(exception)s") %
 118                         {'uri': interface_uri, 'source': source, 'exception': ex})
 119                 raise InvalidInterface(_("Error loading feed '%(uri)s':\n\n%(exception)s") % {'uri': interface_uri, 'exception': ex})
 120         return tmp.last_modified
 121
 122 def update(interface, source, local = False):
 123         """Read in information about an interface.
 124         @param interface: the interface object to update
 125         @type interface: L{model.Interface}
 126         @param source: the name of the file to read
 127         @type source: str
 128         @param local: use file's mtime for last-modified, and uri attribute is ignored
 129         @raise InvalidInterface: if the source's syntax is incorrect
 130         @return: the new feed (since 0.32)
 131         @see: L{update_from_cache}, which calls this"""
 132         assert isinstance(interface, Interface)
 133
 134         try:
 135                 root = qdom.parse(file(source))
 136         except IOError, ex:
 137                 if ex.errno == 2:
 138                         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)
 139                 raise InvalidInterface(_("Can't read file"), ex)
 140         except Exception, ex:
 141                 raise InvalidInterface(_("Invalid XML"), ex)
 142
 143         if local:
 144                 local_path = source
 145         else:
 146                 local_path = None
 147         feed = ZeroInstallFeed(root, local_path, distro.get_host_distribution())
 148         feed.last_modified = int(os.stat(source).st_mtime)
 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         interface._main_feed = feed
 158         return feed