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 import os
   9 from logging import debug, info, warn
  10 from os.path import dirname
  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, injector_gui_uri
  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 %s from %s", interface, 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         # Special case: add our fall-back local copy of the injector as a feed
  49         if interface.uri == injector_gui_uri:
  50                 local_gui = os.path.join(os.path.abspath(dirname(dirname(__file__))), '0launch-gui', 'ZeroInstall-GUI.xml')
  51                 interface.extra_feeds.append(Feed(local_gui, None, False))
  52
  53         return bool(cached)
  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 '%s': %s", user, 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                         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