zeroinstall/injector/model.py

   1 """In-memory representation of interfaces and other data structures.
   2
   3 The objects in this module are used to build a representation of an XML interface
   4 file in memory.
   5
   6 @see: L{reader} constructs these data-structures.
   7
   8 @var defaults: Default values for the 'default' attribute for <environment> bindings of
   9 well-known variables.
  10 """
  11
  12 # Copyright (C) 2006, Thomas Leonard
  13 # See the README file for details, or visit http://0install.net.
  14
  15 import os, re
  16 from logging import warn, info, debug
  17 from zeroinstall import SafeException, version
  18 from zeroinstall.injector.namespaces import XMLNS_IFACE
  19
  20 # Element names for bindings in feed files
  21 binding_names = frozenset(['environment'])
  22
  23 network_offline = 'off-line'
  24 network_minimal = 'minimal'
  25 network_full = 'full'
  26 network_levels = (network_offline, network_minimal, network_full)
  27
  28 stability_levels = {}   # Name -> Stability
  29
  30 defaults = {
  31         'PATH': '/bin:/usr/bin',
  32         'XDG_CONFIG_DIRS': '/etc/xdg',
  33         'XDG_DATA_DIRS': '/usr/local/share:/usr/share',
  34 }
  35
  36 class InvalidInterface(SafeException):
  37         """Raised when parsing an invalid feed."""
  38         def __init__(self, message, ex = None):
  39                 if ex:
  40                         message += "\n\n(exact error: %s)" % ex
  41                 SafeException.__init__(self, message)
  42
  43 def _split_arch(arch):
  44         """Split an arch into an (os, machine) tuple. Either or both parts may be None."""
  45         if not arch:
  46                 return None, None
  47         elif '-' not in arch:
  48                 raise SafeException("Malformed arch '%s'" % arch)
  49         else:
  50                 os, machine = arch.split('-', 1)
  51                 if os == '*': os = None
  52                 if machine == '*': machine = None
  53                 return os, machine
  54
  55 def _join_arch(os, machine):
  56         if os == machine == None: return None
  57         return "%s-%s" % (os or '*', machine or '*')
  58
  59 class Stability(object):
  60         """A stability rating. Each implementation has an upstream stability rating and,
  61         optionally, a user-set rating."""
  62         __slots__ = ['level', 'name', 'description']
  63         def __init__(self, level, name, description):
  64                 self.level = level
  65                 self.name = name
  66                 self.description = description
  67                 assert name not in stability_levels
  68                 stability_levels[name] = self
  69
  70         def __cmp__(self, other):
  71                 return cmp(self.level, other.level)
  72
  73         def __str__(self):
  74                 return self.name
  75
  76         def __repr__(self):
  77                 return "<Stability: " + self.description + ">"
  78
  79 def process_binding(e):
  80         """Internal"""
  81         if e.name == 'environment':
  82                 mode = {
  83                         None: EnvironmentBinding.PREPEND,
  84                         'prepend': EnvironmentBinding.PREPEND,
  85                         'append': EnvironmentBinding.APPEND,
  86                         'replace': EnvironmentBinding.REPLACE,
  87                 }[e.getAttribute('mode')]
  88
  89                 binding = EnvironmentBinding(e.getAttribute('name'),
  90                                              insert = e.getAttribute('insert'),
  91                                              default = e.getAttribute('default'),
  92                                              mode = mode)
  93                 if not binding.name: raise InvalidInterface("Missing 'name' in binding")
  94                 if binding.insert is None: raise InvalidInterface("Missing 'insert' in binding")
  95                 return binding
  96         else:
  97                 raise Exception("Unknown binding type '%s'" % e.name)
  98
  99 def process_depends(item):
 100         """Internal"""
 101         # Note: also called from selections
 102         dep_iface = item.getAttribute('interface')
 103         if not dep_iface:
 104                 raise InvalidInterface("Missing 'interface' on <requires>")
 105         dependency = InterfaceDependency(dep_iface, metadata = item.attrs)
 106
 107         for e in item.childNodes:
 108                 if e.uri != XMLNS_IFACE: continue
 109                 if e.name in binding_names:
 110                         dependency.bindings.append(process_binding(e))
 111                 elif e.name == 'version':
 112                         dependency.restrictions.append(
 113                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 114                                                         before = parse_version(e.getAttribute('before'))))
 115         return dependency
 116
 117
 118 insecure = Stability(0, 'insecure', 'This is a security risk')
 119 buggy = Stability(5, 'buggy', 'Known to have serious bugs')
 120 developer = Stability(10, 'developer', 'Work-in-progress - bugs likely')
 121 testing = Stability(20, 'testing', 'Stability unknown - please test!')
 122 stable = Stability(30, 'stable', 'Tested - no serious problems found')
 123 packaged = Stability(35, 'packaged', 'Supplied by the local package manager')
 124 preferred = Stability(40, 'preferred', 'Best of all - must be set manually')
 125
 126 class Restriction(object):
 127         """A Restriction limits the allowed implementations of an Interface."""
 128         __slots__ = []
 129
 130         def meets_restriction(self, impl):
 131                 raise NotImplementedError("Abstract")
 132
 133 class VersionRangeRestriction(Restriction):
 134         """Only versions within the given range are acceptable"""
 135         __slots__ = ['before', 'not_before']
 136         def __init__(self, before, not_before):
 137                 self.before = before
 138                 self.not_before = not_before
 139
 140         def meets_restriction(self, impl):
 141                 if self.not_before and impl.version < self.not_before:
 142                         return False
 143                 if self.before and impl.version >= self.before:
 144                         return False
 145                 return True
 146
 147         def __str__(self):
 148                 if self.not_before is not None or self.before is not None:
 149                         range = ''
 150                         if self.not_before is not None:
 151                                 range += format_version(self.not_before) + ' <= '
 152                         range += 'version'
 153                         if self.before is not None:
 154                                 range += ' < ' + format_version(self.before)
 155                 else:
 156                         range = 'none'
 157                 return "(restriction: %s)" % range
 158
 159 class Binding(object):
 160         """Information about how the choice of a Dependency is made known
 161         to the application being run."""
 162
 163 class EnvironmentBinding(Binding):
 164         """Indicate the chosen implementation using an environment variable."""
 165         __slots__ = ['name', 'insert', 'default', 'mode']
 166
 167         PREPEND = 'prepend'
 168         APPEND = 'append'
 169         REPLACE = 'replace'
 170
 171         def __init__(self, name, insert, default = None, mode = PREPEND):
 172                 """mode argument added in version 0.28"""
 173                 self.name = name
 174                 self.insert = insert
 175                 self.default = default
 176                 self.mode = mode
 177
 178         def __str__(self):
 179                 return "<environ %s %s %s>" % (self.name, self.mode, self.insert)
 180
 181         __repr__ = __str__
 182
 183         def get_value(self, path, old_value):
 184                 """Calculate the new value of the environment variable after applying this binding.
 185                 @param path: the path to the selected implementation
 186                 @param old_value: the current value of the environment variable
 187                 @return: the new value for the environment variable"""
 188                 extra = os.path.join(path, self.insert)
 189
 190                 if self.mode == EnvironmentBinding.REPLACE:
 191                         return extra
 192
 193                 if old_value is None:
 194                         old_value = self.default or defaults.get(self.name, None)
 195                 if old_value is None:
 196                         return extra
 197                 if self.mode == EnvironmentBinding.PREPEND:
 198                         return extra + ':' + old_value
 199                 else:
 200                         return old_value + ':' + extra
 201
 202         def _toxml(self, doc):
 203                 """Create a DOM element for this binding.
 204                 @param doc: document to use to create the element
 205                 @return: the new element
 206                 """
 207                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 208                 env_elem.setAttributeNS(None, 'name', self.name)
 209                 env_elem.setAttributeNS(None, 'insert', self.insert)
 210                 if self.default:
 211                         env_elem.setAttributeNS(None, 'default', self.default)
 212                 return env_elem
 213
 214 class Feed(object):
 215         """An interface's feeds are other interfaces whose implementations can also be
 216         used as implementations of this interface."""
 217         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs']
 218         def __init__(self, uri, arch, user_override, langs = None):
 219                 self.uri = uri
 220                 # This indicates whether the feed comes from the user's overrides
 221                 # file. If true, writer.py will write it when saving.
 222                 self.user_override = user_override
 223                 self.os, self.machine = _split_arch(arch)
 224                 self.langs = langs
 225
 226         def __str__(self):
 227                 return "<Feed from %s>" % self.uri
 228         __repr__ = __str__
 229
 230         arch = property(lambda self: _join_arch(self.os, self.machine))
 231
 232 class Dependency(object):
 233         """A Dependency indicates that an Implementation requires some additional
 234         code to function. This is an abstract base class.
 235         @ivar metadata: any extra attributes from the XML element
 236         @type metadata: {str: str}
 237         """
 238         __slots__ = ['metadata']
 239
 240         def __init__(self, metadata):
 241                 if metadata is None:
 242                         metadata = {}
 243                 else:
 244                         assert not isinstance(metadata, basestring)     # Use InterfaceDependency instead!
 245                 self.metadata = metadata
 246
 247 class InterfaceDependency(Dependency):
 248         """A Dependency on a Zero Install interface.
 249         @ivar interface: the interface required by this dependency
 250         @type interface: str
 251         @ivar restrictions: a list of constraints on acceptable implementations
 252         @type restrictions: [L{Restriction}]
 253         @ivar bindings: how to make the choice of implementation known
 254         @type bindings: [L{Binding}]
 255         @since: 0.28
 256         """
 257         __slots__ = ['interface', 'restrictions', 'bindings', 'metadata']
 258
 259         def __init__(self, interface, restrictions = None, metadata = None):
 260                 Dependency.__init__(self, metadata)
 261                 assert isinstance(interface, (str, unicode))
 262                 assert interface
 263                 self.interface = interface
 264                 if restrictions is None:
 265                         self.restrictions = []
 266                 else:
 267                         self.restrictions = restrictions
 268                 self.bindings = []
 269
 270         def __str__(self):
 271                 return "<Dependency on %s; bindings: %s%s>" % (self.interface, self.bindings, self.restrictions)
 272
 273 class RetrievalMethod(object):
 274         """A RetrievalMethod provides a way to fetch an implementation."""
 275         __slots__ = []
 276
 277 class DownloadSource(RetrievalMethod):
 278         """A DownloadSource provides a way to fetch an implementation."""
 279         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 280
 281         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 282                 assert url.startswith('http:') or url.startswith('ftp:') or url.startswith('/')
 283                 self.implementation = implementation
 284                 self.url = url
 285                 self.size = size
 286                 self.extract = extract
 287                 self.start_offset = start_offset
 288                 self.type = type                # MIME type - see unpack.py
 289
 290 class Recipe(RetrievalMethod):
 291         """Get an implementation by following a series of steps.
 292         @ivar size: the combined download sizes from all the steps
 293         @type size: int
 294         @ivar steps: the sequence of steps which must be performed
 295         @type steps: [L{RetrievalMethod}]"""
 296         __slots__ = ['steps']
 297
 298         def __init__(self):
 299                 self.steps = []
 300
 301         size = property(lambda self: sum([x.size for x in self.steps]))
 302
 303 class Implementation(object):
 304         """An Implementation is a package which implements an Interface.
 305         @ivar download_sources: list of methods of getting this implementation
 306         @type download_sources: [L{RetrievalMethod}]
 307         @ivar feed: the feed owning this implementation (since 0.32)
 308         @type feed: [L{ZeroInstallFeed}]
 309         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 310         @type bindings: [Binding]
 311         """
 312
 313         # Note: user_stability shouldn't really be here
 314
 315         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 316                      'requires', 'main', 'metadata', 'download_sources',
 317                      'id', 'feed', 'version', 'released', 'bindings']
 318
 319         def __init__(self, feed, id):
 320                 assert id
 321                 self.feed = feed
 322                 self.id = id
 323                 self.main = None
 324                 self.user_stability = None
 325                 self.upstream_stability = None
 326                 self.metadata = {}      # [URI + " "] + localName -> value
 327                 self.requires = []
 328                 self.version = None
 329                 self.released = None
 330                 self.download_sources = []
 331                 self.langs = None
 332                 self.bindings = []
 333
 334         def get_stability(self):
 335                 return self.user_stability or self.upstream_stability or testing
 336
 337         def __str__(self):
 338                 return self.id
 339
 340         def __repr__(self):
 341                 return "v%s (%s)" % (self.get_version(), self.id)
 342
 343         def __cmp__(self, other):
 344                 """Newer versions come first"""
 345                 return cmp(other.version, self.version)
 346
 347         def get_version(self):
 348                 """Return the version as a string.
 349                 @see: L{format_version}
 350                 """
 351                 return format_version(self.version)
 352
 353         arch = property(lambda self: _join_arch(self.os, self.machine))
 354
 355         os = machine = None
 356
 357 class DistributionImplementation(Implementation):
 358         """An implementation provided by the distribution. Information such as the version
 359         comes from the package manager.
 360         @since: 0.28"""
 361         __slots__ = ['installed']
 362
 363         def __init__(self, feed, id):
 364                 assert id.startswith('package:')
 365                 Implementation.__init__(self, feed, id)
 366                 self.installed = True
 367
 368 class ZeroInstallImplementation(Implementation):
 369         """An implementation where all the information comes from Zero Install.
 370         @since: 0.28"""
 371         __slots__ = ['os', 'machine', 'upstream_stability', 'user_stability',
 372                      'size', 'requires', 'main', 'id']
 373
 374         def __init__(self, feed, id):
 375                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 376                 Implementation.__init__(self, feed, id)
 377                 self.size = None
 378                 self.os = None
 379                 self.machine = None
 380
 381         # Deprecated
 382         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 383                                                    if isinstance(x, InterfaceDependency)]))
 384
 385         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 386                 """Add a download source."""
 387                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 388
 389         def set_arch(self, arch):
 390                 self.os, self.machine = _split_arch(arch)
 391         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 392
 393 class Interface(object):
 394         """An Interface represents some contract of behaviour.
 395         @ivar uri: the URI for this interface.
 396         @ivar stability_policy: user's configured policy.
 397         Implementations at this level or higher are preferred.
 398         Lower levels are used only if there is no other choice.
 399         """
 400         __slots__ = ['uri', 'stability_policy', '_main_feed', 'extra_feeds']
 401
 402         implementations = property(lambda self: self._main_feed.implementations)
 403         name = property(lambda self: self._main_feed.name)
 404         description = property(lambda self: self._main_feed.description)
 405         summary = property(lambda self: self._main_feed.summary)
 406         last_modified = property(lambda self: self._main_feed.last_modified)
 407         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 408         metadata = property(lambda self: self._main_feed.metadata)
 409
 410         last_checked = property(lambda self: self._main_feed.last_checked)
 411
 412         def __init__(self, uri):
 413                 assert uri
 414                 if uri.startswith('http:') or uri.startswith('/'):
 415                         self.uri = uri
 416                 else:
 417                         raise SafeException("Interface name '%s' doesn't start "
 418                                             "with 'http:'" % uri)
 419                 self.reset()
 420
 421         def _get_feed_for(self):
 422                 retval = {}
 423                 for key in self._main_feed.feed_for:
 424                         retval[key] = True
 425                 return retval
 426         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 427
 428         def reset(self):
 429                 self.extra_feeds = []
 430                 self._main_feed = _dummy_feed
 431                 self.stability_policy = None
 432
 433         def get_name(self):
 434                 if self._main_feed is not _dummy_feed:
 435                         return self._main_feed.get_name()
 436                 return '(' + os.path.basename(self.uri) + ')'
 437
 438         def __repr__(self):
 439                 return "<Interface %s>" % self.uri
 440
 441         def set_stability_policy(self, new):
 442                 assert new is None or isinstance(new, Stability)
 443                 self.stability_policy = new
 444
 445         def get_feed(self, url):
 446                 for x in self.extra_feeds:
 447                         if x.uri == url:
 448                                 return x
 449                 return self._main_feed.get_feed(url)
 450
 451         def get_metadata(self, uri, name):
 452                 return self._main_feed.get_metadata(uri, name)
 453
 454 def _merge_attrs(attrs, item):
 455         """Add each attribute of item to a copy of attrs and return the copy.
 456         @type attrs: {str: str}
 457         @type item: L{qdom.Element}
 458         @rtype: {str: str}
 459         """
 460         new = attrs.copy()
 461         for a in item.attrs:
 462                 new[str(a)] = item.attrs[a]
 463         return new
 464
 465 def _get_long(elem, attr_name):
 466         val = elem.getAttribute(attr_name)
 467         if val is not None:
 468                 try:
 469                         val = long(val)
 470                 except ValueError, ex:
 471                         raise SafeException("Invalid value for integer attribute '%s': %s" % (attr_name, val))
 472         return val
 473
 474 class ZeroInstallFeed(object):
 475         """A feed lists available implementations of an interface.
 476         @ivar url: the URL for this feed
 477         @ivar implementations: Implementations in this feed, indexed by ID
 478         @type implementations: {str: L{Implementation}}
 479         @ivar name: human-friendly name
 480         @ivar summary: short textual description
 481         @ivar description: long textual description
 482         @ivar last_modified: timestamp on signature
 483         @ivar last_checked: time feed was last successfully downloaded and updated
 484         @ivar feeds: list of <feed> elements in this feed
 485         @type feeds: [L{Feed}]
 486         @ivar feed_for: interfaces for which this could be a feed
 487         @type feed_for: set(str)
 488         @ivar metadata: extra elements we didn't understand
 489         """
 490         # _main is deprecated
 491         __slots__ = ['url', 'implementations', 'name', 'description', 'summary',
 492                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata']
 493
 494         def __init__(self, feed_element, local_path = None, distro = None):
 495                 """Create a feed object from a DOM.
 496                 @param feed_element: the root element of a feed file
 497                 @type feed_element: L{qdom.Element}
 498                 @param interface: temporary hack for restructuring. will go away.
 499                 @param local_name: the pathname of this local feed, or None for remote feeds
 500                 @param distro: used to resolve distribution package references
 501                 @type distro: L{distro.Distribution} or None"""
 502                 assert feed_element
 503                 self.implementations = {}
 504                 self.name = None
 505                 self.summary = None
 506                 self.description = ""
 507                 self.last_modified = None
 508                 self.feeds = []
 509                 self.feed_for = set()
 510                 self.metadata = []
 511                 self.last_checked = None
 512
 513                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 514                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 515
 516                 main = feed_element.getAttribute('main')
 517                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 518
 519                 if local_path:
 520                         self.url = local_path
 521                         local_dir = os.path.dirname(local_path)
 522                 else:
 523                         self.url = feed_element.getAttribute('uri')
 524                         if not self.url:
 525                                 raise InvalidInterface("<interface> uri attribute missing")
 526                         local_dir = None        # Can't have relative paths
 527
 528                 min_injector_version = feed_element.getAttribute('min-injector-version')
 529                 if min_injector_version:
 530                         if parse_version(min_injector_version) > parse_version(version):
 531                                 raise InvalidInterface("This feed requires version %s or later of "
 532                                                         "Zero Install, but I am only version %s. "
 533                                                         "You can get a newer version from http://0install.net" %
 534                                                         (min_injector_version, version))
 535
 536                 for x in feed_element.childNodes:
 537                         if x.uri != XMLNS_IFACE:
 538                                 self.metadata.append(x)
 539                                 continue
 540                         if x.name == 'name':
 541                                 self.name = x.content
 542                         elif x.name == 'description':
 543                                 self.description = x.content
 544                         elif x.name == 'summary':
 545                                 self.summary = x.content
 546                         elif x.name == 'feed-for':
 547                                 feed_iface = x.getAttribute('interface')
 548                                 if not feed_iface:
 549                                         raise InvalidInterface('Missing "interface" attribute in <feed-for>')
 550                                 self.feed_for.add(feed_iface)
 551                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
 552                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
 553                                 # in case it happens again.
 554                                 debug("Is feed-for %s", feed_iface)
 555                         elif x.name == 'feed':
 556                                 feed_src = x.getAttribute('src')
 557                                 if not feed_src:
 558                                         raise InvalidInterface('Missing "src" attribute in <feed>')
 559                                 if feed_src.startswith('http:') or local_path:
 560                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = x.getAttribute('langs')))
 561                                 else:
 562                                         raise InvalidInterface("Invalid feed URL '%s'" % feed_src)
 563                         else:
 564                                 self.metadata.append(x)
 565
 566                 if not self.name:
 567                         raise InvalidInterface("Missing <name> in feed")
 568                 if not self.summary:
 569                         raise InvalidInterface("Missing <summary> in feed")
 570
 571                 def process_group(group, group_attrs, base_depends, base_bindings):
 572                         for item in group.childNodes:
 573                                 if item.uri != XMLNS_IFACE: continue
 574
 575                                 if item.name not in ('group', 'implementation', 'package-implementation'):
 576                                         continue
 577
 578                                 depends = base_depends[:]
 579                                 bindings = base_bindings[:]
 580
 581                                 item_attrs = _merge_attrs(group_attrs, item)
 582
 583                                 # We've found a group or implementation. Scan for dependencies
 584                                 # and bindings. Doing this here means that:
 585                                 # - We can share the code for groups and implementations here.
 586                                 # - The order doesn't matter, because these get processed first.
 587                                 # A side-effect is that the document root cannot contain
 588                                 # these.
 589                                 for child in item.childNodes:
 590                                         if child.uri != XMLNS_IFACE: continue
 591                                         if child.name == 'requires':
 592                                                 dep = process_depends(child)
 593                                                 depends.append(dep)
 594                                         elif child.name in binding_names:
 595                                                 bindings.append(process_binding(child))
 596
 597                                 if item.name == 'group':
 598                                         process_group(item, item_attrs, depends, bindings)
 599                                 elif item.name == 'implementation':
 600                                         process_impl(item, item_attrs, depends, bindings)
 601                                 elif item.name == 'package-implementation':
 602                                         process_native_impl(item, item_attrs, depends)
 603                                 else:
 604                                         assert 0
 605
 606                 def process_impl(item, item_attrs, depends, bindings):
 607                         id = item.getAttribute('id')
 608                         if id is None:
 609                                 raise InvalidInterface("Missing 'id' attribute on %s" % item)
 610                         if local_dir and (id.startswith('/') or id.startswith('.')):
 611                                 impl = self._get_impl(os.path.abspath(os.path.join(local_dir, id)))
 612                         else:
 613                                 if '=' not in id:
 614                                         raise InvalidInterface('Invalid "id"; form is "alg=value" (got "%s")' % id)
 615                                 alg, sha1 = id.split('=')
 616                                 try:
 617                                         long(sha1, 16)
 618                                 except Exception, ex:
 619                                         raise InvalidInterface('Bad SHA1 attribute: %s' % ex)
 620                                 impl = self._get_impl(id)
 621
 622                         impl.metadata = item_attrs
 623                         try:
 624                                 version = item_attrs['version']
 625                                 version_mod = item_attrs.get('version-modifier', None)
 626                                 if version_mod: version += version_mod
 627                         except KeyError:
 628                                 raise InvalidInterface("Missing version attribute")
 629                         impl.version = parse_version(version)
 630
 631                         item_main = item_attrs.get('main', None)
 632                         if item_main and item_main.startswith('/'):
 633                                 raise InvalidInterface("'main' attribute must be relative, but '%s' starts with '/'!" %
 634                                                         item_main)
 635                         impl.main = item_main
 636
 637                         impl.released = item_attrs.get('released', None)
 638                         impl.langs = item_attrs.get('langs', None)
 639
 640                         size = item.getAttribute('size')
 641                         if size:
 642                                 impl.size = long(size)
 643                         impl.arch = item_attrs.get('arch', None)
 644                         try:
 645                                 stability = stability_levels[str(item_attrs['stability'])]
 646                         except KeyError:
 647                                 stab = str(item_attrs['stability'])
 648                                 if stab != stab.lower():
 649                                         raise InvalidInterface('Stability "%s" invalid - use lower case!' % item_attrs.stability)
 650                                 raise InvalidInterface('Stability "%s" invalid' % item_attrs['stability'])
 651                         if stability >= preferred:
 652                                 raise InvalidInterface("Upstream can't set stability to preferred!")
 653                         impl.upstream_stability = stability
 654
 655                         impl.bindings = bindings
 656                         impl.requires = depends
 657
 658                         for elem in item.childNodes:
 659                                 if elem.uri != XMLNS_IFACE: continue
 660                                 if elem.name == 'archive':
 661                                         url = elem.getAttribute('href')
 662                                         if not url:
 663                                                 raise InvalidInterface("Missing href attribute on <archive>")
 664                                         size = elem.getAttribute('size')
 665                                         if not size:
 666                                                 raise InvalidInterface("Missing size attribute on <archive>")
 667                                         impl.add_download_source(url = url, size = long(size),
 668                                                         extract = elem.getAttribute('extract'),
 669                                                         start_offset = _get_long(elem, 'start-offset'),
 670                                                         type = elem.getAttribute('type'))
 671                                 elif elem.name == 'recipe':
 672                                         recipe = Recipe()
 673                                         for recipe_step in elem.childNodes:
 674                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
 675                                                         url = recipe_step.getAttribute('href')
 676                                                         if not url:
 677                                                                 raise InvalidInterface("Missing href attribute on <archive>")
 678                                                         size = recipe_step.getAttribute('size')
 679                                                         if not size:
 680                                                                 raise InvalidInterface("Missing size attribute on <archive>")
 681                                                         recipe.steps.append(DownloadSource(None, url = url, size = long(size),
 682                                                                         extract = recipe_step.getAttribute('extract'),
 683                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
 684                                                                         type = recipe_step.getAttribute('type')))
 685                                                 else:
 686                                                         info("Unknown step '%s' in recipe; skipping recipe", recipe_step.name)
 687                                                         break
 688                                         else:
 689                                                 impl.download_sources.append(recipe)
 690
 691                 def process_native_impl(item, item_attrs, depends):
 692                         package = item_attrs.get('package', None)
 693                         if package is None:
 694                                 raise InvalidInterface("Missing 'package' attribute on %s" % item)
 695
 696                         def factory(id):
 697                                 assert id.startswith('package:')
 698                                 impl = self._get_impl(id)
 699
 700                                 impl.metadata = item_attrs
 701
 702                                 item_main = item_attrs.get('main', None)
 703                                 if item_main and not item_main.startswith('/'):
 704                                         raise InvalidInterface("'main' attribute must be absolute, but '%s' doesn't start with '/'!" %
 705                                                                 item_main)
 706                                 impl.main = item_main
 707                                 impl.upstream_stability = packaged
 708                                 impl.requires = depends
 709
 710                                 return impl
 711
 712                         distro.get_package_info(package, factory)
 713
 714                 process_group(feed_element,
 715                         {'stability': 'testing',
 716                          'main' : main,
 717                         },
 718                         [], [])
 719
 720         def get_name(self):
 721                 return self.name or '(' + os.path.basename(self.url) + ')'
 722
 723         def __repr__(self):
 724                 return "<Feed %s>" % self.url
 725
 726         def _get_impl(self, id):
 727                 if id not in self.implementations:
 728                         if id.startswith('package:'):
 729                                 impl = DistributionImplementation(self, id)
 730                         else:
 731                                 impl = ZeroInstallImplementation(self, id)
 732                         self.implementations[id] = impl
 733                 return self.implementations[id]
 734
 735         def set_stability_policy(self, new):
 736                 assert new is None or isinstance(new, Stability)
 737                 self.stability_policy = new
 738
 739         def get_feed(self, url):
 740                 for x in self.feeds:
 741                         if x.uri == url:
 742                                 return x
 743                 return None
 744
 745         def add_metadata(self, elem):
 746                 self.metadata.append(elem)
 747
 748         def get_metadata(self, uri, name):
 749                 """Return a list of interface metadata elements with this name and namespace URI."""
 750                 return [m for m in self.metadata if m.name == name and m.uri == uri]
 751
 752 class DummyFeed(object):
 753         last_modified = None
 754         name = '-'
 755         last_checked = property(lambda self: None)
 756         implementations = property(lambda self: {})
 757         feeds = property(lambda self: [])
 758         summary = property(lambda self: '-')
 759         description = property(lambda self: '')
 760         def get_name(self): return self.name
 761         def get_feed(self, url): return None
 762         def get_metadata(self, uri, name): return []
 763 _dummy_feed = DummyFeed()
 764
 765 def unescape(uri):
 766         """Convert each %20 to a space, etc.
 767         @rtype: str"""
 768         uri = uri.replace('#', '/')
 769         if '%' not in uri: return uri
 770         return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
 771                 lambda match: chr(int(match.group(0)[1:], 16)),
 772                 uri).decode('utf-8')
 773
 774 def escape(uri):
 775         """Convert each space to %20, etc
 776         @rtype: str"""
 777         return re.sub('[^-_.a-zA-Z0-9]',
 778                 lambda match: '%%%02x' % ord(match.group(0)),
 779                 uri.encode('utf-8'))
 780
 781 def _pretty_escape(uri):
 782         """Convert each space to %20, etc
 783         : is preserved and / becomes #. This makes for nicer strings,
 784         and may replace L{escape} everywhere in future.
 785         @rtype: str"""
 786         return re.sub('[^-_.a-zA-Z0-9:/]',
 787                 lambda match: '%%%02x' % ord(match.group(0)),
 788                 uri.encode('utf-8')).replace('/', '#')
 789
 790 def canonical_iface_uri(uri):
 791         """If uri is a relative path, convert to an absolute one.
 792         Otherwise, return it unmodified.
 793         @rtype: str
 794         @raise SafeException: if uri isn't valid
 795         """
 796         if uri.startswith('http:'):
 797                 return uri
 798         else:
 799                 iface_uri = os.path.realpath(uri)
 800                 if os.path.isfile(iface_uri):
 801                         return iface_uri
 802         raise SafeException("Bad interface name '%s'.\n"
 803                         "(doesn't start with 'http:', and "
 804                         "doesn't exist as a local file '%s' either)" %
 805                         (uri, iface_uri))
 806
 807 _version_mod_to_value = {
 808         'pre': -2,
 809         'rc': -1,
 810         '': 0,
 811         'post': 1,
 812 }
 813
 814 # Reverse mapping
 815 _version_value_to_mod = {}
 816 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
 817 del x
 818
 819 _version_re = re.compile('-([a-z]*)')
 820
 821 def parse_version(version_string):
 822         """Convert a version string to an internal representation.
 823         The parsed format can be compared quickly using the standard Python functions.
 824          - Version := DottedList ("-" Mod DottedList?)*
 825          - DottedList := (Integer ("." Integer)*)
 826         @rtype: tuple (opaque)
 827         @raise SafeException: if the string isn't a valid version
 828         @since: 0.24 (moved from L{reader}, from where it is still available):"""
 829         if version_string is None: return None
 830         parts = _version_re.split(version_string)
 831         if parts[-1] == '':
 832                 del parts[-1]   # Ends with a modifier
 833         else:
 834                 parts.append('')
 835         if not parts:
 836                 raise SafeException("Empty version string!")
 837         l = len(parts)
 838         try:
 839                 for x in range(0, l, 2):
 840                         part = parts[x]
 841                         if part:
 842                                 parts[x] = map(int, parts[x].split('.'))
 843                         else:
 844                                 parts[x] = []   # (because ''.split('.') == [''], not [])
 845                 for x in range(1, l, 2):
 846                         parts[x] = _version_mod_to_value[parts[x]]
 847                 return parts
 848         except ValueError, ex:
 849                 raise SafeException("Invalid version format in '%s': %s" % (version_string, ex))
 850         except KeyError, ex:
 851                 raise SafeException("Invalid version modifier in '%s': %s" % (version_string, ex))
 852
 853 def format_version(version):
 854         """Format a parsed version for display. Undoes the effect of L{parse_version}.
 855         @see: L{Implementation.get_version}
 856         @rtype: str
 857         @since: 0.24"""
 858         version = version[:]
 859         l = len(version)
 860         for x in range(0, l, 2):
 861                 version[x] = '.'.join(map(str, version[x]))
 862         for x in range(1, l, 2):
 863                 version[x] = '-' + _version_value_to_mod[version[x]]
 864         if version[-1] == '-': del version[-1]
 865         return ''.join(version)
 866