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 @see: U{http://0install.net/interface-spec.html} description of the domain model
   8
   9 @var defaults: Default values for the 'default' attribute for <environment> bindings of
  10 well-known variables.
  11 """
  12
  13 # Copyright (C) 2009, Thomas Leonard
  14 # See the README file for details, or visit http://0install.net.
  15
  16 import os, re
  17 from logging import info, debug
  18 from zeroinstall import SafeException, version
  19 from zeroinstall.injector.namespaces import XMLNS_IFACE
  20
  21 # Element names for bindings in feed files
  22 binding_names = frozenset(['environment', 'overlay'])
  23
  24 network_offline = 'off-line'
  25 network_minimal = 'minimal'
  26 network_full = 'full'
  27 network_levels = (network_offline, network_minimal, network_full)
  28
  29 stability_levels = {}   # Name -> Stability
  30
  31 defaults = {
  32         'PATH': '/bin:/usr/bin',
  33         'XDG_CONFIG_DIRS': '/etc/xdg',
  34         'XDG_DATA_DIRS': '/usr/local/share:/usr/share',
  35 }
  36
  37 class InvalidInterface(SafeException):
  38         """Raised when parsing an invalid feed."""
  39         def __init__(self, message, ex = None):
  40                 if ex:
  41                         message += "\n\n(exact error: %s)" % ex
  42                 SafeException.__init__(self, message)
  43
  44 def _split_arch(arch):
  45         """Split an arch into an (os, machine) tuple. Either or both parts may be None."""
  46         if not arch:
  47                 return None, None
  48         elif '-' not in arch:
  49                 raise SafeException("Malformed arch '%s'" % arch)
  50         else:
  51                 osys, machine = arch.split('-', 1)
  52                 if osys == '*': osys = None
  53                 if machine == '*': machine = None
  54                 return osys, machine
  55
  56 def _join_arch(osys, machine):
  57         if osys == machine == None: return None
  58         return "%s-%s" % (osys or '*', machine or '*')
  59
  60 class Stability(object):
  61         """A stability rating. Each implementation has an upstream stability rating and,
  62         optionally, a user-set rating."""
  63         __slots__ = ['level', 'name', 'description']
  64         def __init__(self, level, name, description):
  65                 self.level = level
  66                 self.name = name
  67                 self.description = description
  68                 assert name not in stability_levels
  69                 stability_levels[name] = self
  70
  71         def __cmp__(self, other):
  72                 return cmp(self.level, other.level)
  73
  74         def __str__(self):
  75                 return self.name
  76
  77         def __repr__(self):
  78                 return "<Stability: " + self.description + ">"
  79
  80 def process_binding(e):
  81         """Internal"""
  82         if e.name == 'environment':
  83                 mode = {
  84                         None: EnvironmentBinding.PREPEND,
  85                         'prepend': EnvironmentBinding.PREPEND,
  86                         'append': EnvironmentBinding.APPEND,
  87                         'replace': EnvironmentBinding.REPLACE,
  88                 }[e.getAttribute('mode')]
  89
  90                 binding = EnvironmentBinding(e.getAttribute('name'),
  91                                              insert = e.getAttribute('insert'),
  92                                              default = e.getAttribute('default'),
  93                                              mode = mode)
  94                 if not binding.name: raise InvalidInterface("Missing 'name' in binding")
  95                 if binding.insert is None: raise InvalidInterface("Missing 'insert' in binding")
  96                 return binding
  97         elif e.name == 'overlay':
  98                 return OverlayBinding(e.getAttribute('src'), e.getAttribute('mount-point'))
  99         else:
 100                 raise Exception("Unknown binding type '%s'" % e.name)
 101
 102 def process_depends(item):
 103         """Internal"""
 104         # Note: also called from selections
 105         dep_iface = item.getAttribute('interface')
 106         if not dep_iface:
 107                 raise InvalidInterface("Missing 'interface' on <requires>")
 108         dependency = InterfaceDependency(dep_iface, metadata = item.attrs)
 109
 110         for e in item.childNodes:
 111                 if e.uri != XMLNS_IFACE: continue
 112                 if e.name in binding_names:
 113                         dependency.bindings.append(process_binding(e))
 114                 elif e.name == 'version':
 115                         dependency.restrictions.append(
 116                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 117                                                         before = parse_version(e.getAttribute('before'))))
 118         return dependency
 119
 120
 121 insecure = Stability(0, 'insecure', 'This is a security risk')
 122 buggy = Stability(5, 'buggy', 'Known to have serious bugs')
 123 developer = Stability(10, 'developer', 'Work-in-progress - bugs likely')
 124 testing = Stability(20, 'testing', 'Stability unknown - please test!')
 125 stable = Stability(30, 'stable', 'Tested - no serious problems found')
 126 packaged = Stability(35, 'packaged', 'Supplied by the local package manager')
 127 preferred = Stability(40, 'preferred', 'Best of all - must be set manually')
 128
 129 class Restriction(object):
 130         """A Restriction limits the allowed implementations of an Interface."""
 131         __slots__ = []
 132
 133         def meets_restriction(self, impl):
 134                 raise NotImplementedError("Abstract")
 135
 136 class VersionRangeRestriction(Restriction):
 137         """Only versions within the given range are acceptable"""
 138         __slots__ = ['before', 'not_before']
 139         def __init__(self, before, not_before):
 140                 self.before = before
 141                 self.not_before = not_before
 142
 143         def meets_restriction(self, impl):
 144                 if self.not_before and impl.version < self.not_before:
 145                         return False
 146                 if self.before and impl.version >= self.before:
 147                         return False
 148                 return True
 149
 150         def __str__(self):
 151                 if self.not_before is not None or self.before is not None:
 152                         range = ''
 153                         if self.not_before is not None:
 154                                 range += format_version(self.not_before) + ' <= '
 155                         range += 'version'
 156                         if self.before is not None:
 157                                 range += ' < ' + format_version(self.before)
 158                 else:
 159                         range = 'none'
 160                 return "(restriction: %s)" % range
 161
 162 class Binding(object):
 163         """Information about how the choice of a Dependency is made known
 164         to the application being run."""
 165
 166 class EnvironmentBinding(Binding):
 167         """Indicate the chosen implementation using an environment variable."""
 168         __slots__ = ['name', 'insert', 'default', 'mode']
 169
 170         PREPEND = 'prepend'
 171         APPEND = 'append'
 172         REPLACE = 'replace'
 173
 174         def __init__(self, name, insert, default = None, mode = PREPEND):
 175                 """mode argument added in version 0.28"""
 176                 self.name = name
 177                 self.insert = insert
 178                 self.default = default
 179                 self.mode = mode
 180
 181         def __str__(self):
 182                 return "<environ %s %s %s>" % (self.name, self.mode, self.insert)
 183
 184         __repr__ = __str__
 185
 186         def get_value(self, path, old_value):
 187                 """Calculate the new value of the environment variable after applying this binding.
 188                 @param path: the path to the selected implementation
 189                 @param old_value: the current value of the environment variable
 190                 @return: the new value for the environment variable"""
 191                 extra = os.path.join(path, self.insert)
 192
 193                 if self.mode == EnvironmentBinding.REPLACE:
 194                         return extra
 195
 196                 if old_value is None:
 197                         old_value = self.default or defaults.get(self.name, None)
 198                 if old_value is None:
 199                         return extra
 200                 if self.mode == EnvironmentBinding.PREPEND:
 201                         return extra + ':' + old_value
 202                 else:
 203                         return old_value + ':' + extra
 204
 205         def _toxml(self, doc):
 206                 """Create a DOM element for this binding.
 207                 @param doc: document to use to create the element
 208                 @return: the new element
 209                 """
 210                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 211                 env_elem.setAttributeNS(None, 'name', self.name)
 212                 env_elem.setAttributeNS(None, 'insert', self.insert)
 213                 if self.default:
 214                         env_elem.setAttributeNS(None, 'default', self.default)
 215                 return env_elem
 216
 217 class OverlayBinding(Binding):
 218         """Make the chosen implementation available by overlaying it onto another part of the file-system.
 219         This is to support legacy programs which use hard-coded paths."""
 220         __slots__ = ['src', 'mount_point']
 221
 222         def __init__(self, src, mount_point):
 223                 self.src = src
 224                 self.mount_point = mount_point
 225
 226         def __str__(self):
 227                 return "<overlay %s on %s>" % (self.src or '.', self.mount_point or '/')
 228
 229         __repr__ = __str__
 230
 231         def _toxml(self, doc):
 232                 """Create a DOM element for this binding.
 233                 @param doc: document to use to create the element
 234                 @return: the new element
 235                 """
 236                 env_elem = doc.createElementNS(XMLNS_IFACE, 'overlay')
 237                 if self.src is not None:
 238                         env_elem.setAttributeNS(None, 'src', self.src)
 239                 if self.mount_point is not None:
 240                         env_elem.setAttributeNS(None, 'mount-point', self.mount_point)
 241                 return env_elem
 242
 243 class Feed(object):
 244         """An interface's feeds are other interfaces whose implementations can also be
 245         used as implementations of this interface."""
 246         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs']
 247         def __init__(self, uri, arch, user_override, langs = None):
 248                 self.uri = uri
 249                 # This indicates whether the feed comes from the user's overrides
 250                 # file. If true, writer.py will write it when saving.
 251                 self.user_override = user_override
 252                 self.os, self.machine = _split_arch(arch)
 253                 self.langs = langs
 254
 255         def __str__(self):
 256                 return "<Feed from %s>" % self.uri
 257         __repr__ = __str__
 258
 259         arch = property(lambda self: _join_arch(self.os, self.machine))
 260
 261 class Dependency(object):
 262         """A Dependency indicates that an Implementation requires some additional
 263         code to function. This is an abstract base class.
 264         @ivar metadata: any extra attributes from the XML element
 265         @type metadata: {str: str}
 266         """
 267         __slots__ = ['metadata']
 268
 269         def __init__(self, metadata):
 270                 if metadata is None:
 271                         metadata = {}
 272                 else:
 273                         assert not isinstance(metadata, basestring)     # Use InterfaceDependency instead!
 274                 self.metadata = metadata
 275
 276 class InterfaceDependency(Dependency):
 277         """A Dependency on a Zero Install interface.
 278         @ivar interface: the interface required by this dependency
 279         @type interface: str
 280         @ivar restrictions: a list of constraints on acceptable implementations
 281         @type restrictions: [L{Restriction}]
 282         @ivar bindings: how to make the choice of implementation known
 283         @type bindings: [L{Binding}]
 284         @since: 0.28
 285         """
 286         __slots__ = ['interface', 'restrictions', 'bindings', 'metadata']
 287
 288         def __init__(self, interface, restrictions = None, metadata = None):
 289                 Dependency.__init__(self, metadata)
 290                 assert isinstance(interface, (str, unicode))
 291                 assert interface
 292                 self.interface = interface
 293                 if restrictions is None:
 294                         self.restrictions = []
 295                 else:
 296                         self.restrictions = restrictions
 297                 self.bindings = []
 298
 299         def __str__(self):
 300                 return "<Dependency on %s; bindings: %s%s>" % (self.interface, self.bindings, self.restrictions)
 301
 302 class RetrievalMethod(object):
 303         """A RetrievalMethod provides a way to fetch an implementation."""
 304         __slots__ = []
 305
 306 class DownloadSource(RetrievalMethod):
 307         """A DownloadSource provides a way to fetch an implementation."""
 308         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 309
 310         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 311                 self.implementation = implementation
 312                 self.url = url
 313                 self.size = size
 314                 self.extract = extract
 315                 self.start_offset = start_offset
 316                 self.type = type                # MIME type - see unpack.py
 317
 318 class Recipe(RetrievalMethod):
 319         """Get an implementation by following a series of steps.
 320         @ivar size: the combined download sizes from all the steps
 321         @type size: int
 322         @ivar steps: the sequence of steps which must be performed
 323         @type steps: [L{RetrievalMethod}]"""
 324         __slots__ = ['steps']
 325
 326         def __init__(self):
 327                 self.steps = []
 328
 329         size = property(lambda self: sum([x.size for x in self.steps]))
 330
 331 class Implementation(object):
 332         """An Implementation is a package which implements an Interface.
 333         @ivar download_sources: list of methods of getting this implementation
 334         @type download_sources: [L{RetrievalMethod}]
 335         @ivar feed: the feed owning this implementation (since 0.32)
 336         @type feed: [L{ZeroInstallFeed}]
 337         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 338         @type bindings: [Binding]
 339         @ivar upstream_stability: the stability reported by the packager
 340         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged]
 341         @ivar user_stability: the stability as set by the user
 342         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged | preferred]
 343         @ivar langs: natural languages supported by this package
 344         @ivar requires: interfaces this package depends on
 345         @ivar main: the default file to execute when running as a program
 346         @ivar metadata: extra metadata from the feed
 347         @type metadata: {"[URI ]localName": str}
 348         @ivar id: a unique identifier for this Implementation
 349         @ivar version: a parsed version number
 350         @ivar released: release date
 351         """
 352
 353         # Note: user_stability shouldn't really be here
 354
 355         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 356                      'requires', 'main', 'metadata', 'download_sources',
 357                      'id', 'feed', 'version', 'released', 'bindings', 'machine']
 358
 359         def __init__(self, feed, id):
 360                 assert id
 361                 self.feed = feed
 362                 self.id = id
 363                 self.main = None
 364                 self.user_stability = None
 365                 self.upstream_stability = None
 366                 self.metadata = {}      # [URI + " "] + localName -> value
 367                 self.requires = []
 368                 self.version = None
 369                 self.released = None
 370                 self.download_sources = []
 371                 self.langs = None
 372                 self.machine = None
 373                 self.bindings = []
 374
 375         def get_stability(self):
 376                 return self.user_stability or self.upstream_stability or testing
 377
 378         def __str__(self):
 379                 return self.id
 380
 381         def __repr__(self):
 382                 return "v%s (%s)" % (self.get_version(), self.id)
 383
 384         def __cmp__(self, other):
 385                 """Newer versions come first"""
 386                 return cmp(other.version, self.version)
 387
 388         def get_version(self):
 389                 """Return the version as a string.
 390                 @see: L{format_version}
 391                 """
 392                 return format_version(self.version)
 393
 394         arch = property(lambda self: _join_arch(self.os, self.machine))
 395
 396         os = None
 397
 398 class DistributionImplementation(Implementation):
 399         """An implementation provided by the distribution. Information such as the version
 400         comes from the package manager.
 401         @since: 0.28"""
 402         __slots__ = ['installed']
 403
 404         def __init__(self, feed, id):
 405                 assert id.startswith('package:')
 406                 Implementation.__init__(self, feed, id)
 407                 self.installed = True
 408
 409 class ZeroInstallImplementation(Implementation):
 410         """An implementation where all the information comes from Zero Install.
 411         @since: 0.28"""
 412         __slots__ = ['os', 'size']
 413
 414         def __init__(self, feed, id):
 415                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 416                 Implementation.__init__(self, feed, id)
 417                 self.size = None
 418                 self.os = None
 419
 420         # Deprecated
 421         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 422                                                    if isinstance(x, InterfaceDependency)]))
 423
 424         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 425                 """Add a download source."""
 426                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 427
 428         def set_arch(self, arch):
 429                 self.os, self.machine = _split_arch(arch)
 430         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 431
 432 class Interface(object):
 433         """An Interface represents some contract of behaviour.
 434         @ivar uri: the URI for this interface.
 435         @ivar stability_policy: user's configured policy.
 436         Implementations at this level or higher are preferred.
 437         Lower levels are used only if there is no other choice.
 438         """
 439         __slots__ = ['uri', 'stability_policy', '_main_feed', 'extra_feeds']
 440
 441         implementations = property(lambda self: self._main_feed.implementations)
 442         name = property(lambda self: self._main_feed.name)
 443         description = property(lambda self: self._main_feed.description)
 444         summary = property(lambda self: self._main_feed.summary)
 445         last_modified = property(lambda self: self._main_feed.last_modified)
 446         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 447         metadata = property(lambda self: self._main_feed.metadata)
 448
 449         last_checked = property(lambda self: self._main_feed.last_checked)
 450
 451         def __init__(self, uri):
 452                 assert uri
 453                 if uri.startswith('http:') or uri.startswith('/'):
 454                         self.uri = uri
 455                 else:
 456                         raise SafeException("Interface name '%s' doesn't start "
 457                                             "with 'http:'" % uri)
 458                 self.reset()
 459
 460         def _get_feed_for(self):
 461                 retval = {}
 462                 for key in self._main_feed.feed_for:
 463                         retval[key] = True
 464                 return retval
 465         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 466
 467         def reset(self):
 468                 self.extra_feeds = []
 469                 self._main_feed = _dummy_feed
 470                 self.stability_policy = None
 471
 472         def get_name(self):
 473                 if self._main_feed is not _dummy_feed:
 474                         return self._main_feed.get_name()
 475                 return '(' + os.path.basename(self.uri) + ')'
 476
 477         def __repr__(self):
 478                 return "<Interface %s>" % self.uri
 479
 480         def set_stability_policy(self, new):
 481                 assert new is None or isinstance(new, Stability)
 482                 self.stability_policy = new
 483
 484         def get_feed(self, url):
 485                 for x in self.extra_feeds:
 486                         if x.uri == url:
 487                                 return x
 488                 return self._main_feed.get_feed(url)
 489
 490         def get_metadata(self, uri, name):
 491                 return self._main_feed.get_metadata(uri, name)
 492
 493 def _merge_attrs(attrs, item):
 494         """Add each attribute of item to a copy of attrs and return the copy.
 495         @type attrs: {str: str}
 496         @type item: L{qdom.Element}
 497         @rtype: {str: str}
 498         """
 499         new = attrs.copy()
 500         for a in item.attrs:
 501                 new[str(a)] = item.attrs[a]
 502         return new
 503
 504 def _get_long(elem, attr_name):
 505         val = elem.getAttribute(attr_name)
 506         if val is not None:
 507                 try:
 508                         val = long(val)
 509                 except ValueError, ex:
 510                         raise SafeException("Invalid value for integer attribute '%s': %s" % (attr_name, val))
 511         return val
 512
 513 class ZeroInstallFeed(object):
 514         """A feed lists available implementations of an interface.
 515         @ivar url: the URL for this feed
 516         @ivar implementations: Implementations in this feed, indexed by ID
 517         @type implementations: {str: L{Implementation}}
 518         @ivar name: human-friendly name
 519         @ivar summary: short textual description
 520         @ivar description: long textual description
 521         @ivar last_modified: timestamp on signature
 522         @ivar last_checked: time feed was last successfully downloaded and updated
 523         @ivar feeds: list of <feed> elements in this feed
 524         @type feeds: [L{Feed}]
 525         @ivar feed_for: interfaces for which this could be a feed
 526         @type feed_for: set(str)
 527         @ivar metadata: extra elements we didn't understand
 528         """
 529         # _main is deprecated
 530         __slots__ = ['url', 'implementations', 'name', 'description', 'summary',
 531                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata']
 532
 533         def __init__(self, feed_element, local_path = None, distro = None):
 534                 """Create a feed object from a DOM.
 535                 @param feed_element: the root element of a feed file
 536                 @type feed_element: L{qdom.Element}
 537                 @param local_path: the pathname of this local feed, or None for remote feeds
 538                 @param distro: used to resolve distribution package references
 539                 @type distro: L{distro.Distribution} or None"""
 540                 assert feed_element
 541                 self.implementations = {}
 542                 self.name = None
 543                 self.summary = None
 544                 self.description = ""
 545                 self.last_modified = None
 546                 self.feeds = []
 547                 self.feed_for = set()
 548                 self.metadata = []
 549                 self.last_checked = None
 550
 551                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 552                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 553
 554                 main = feed_element.getAttribute('main')
 555                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 556
 557                 if local_path:
 558                         self.url = local_path
 559                         local_dir = os.path.dirname(local_path)
 560                 else:
 561                         self.url = feed_element.getAttribute('uri')
 562                         if not self.url:
 563                                 raise InvalidInterface("<interface> uri attribute missing")
 564                         local_dir = None        # Can't have relative paths
 565
 566                 min_injector_version = feed_element.getAttribute('min-injector-version')
 567                 if min_injector_version:
 568                         if parse_version(min_injector_version) > parse_version(version):
 569                                 raise InvalidInterface("This feed requires version %s or later of "
 570                                                         "Zero Install, but I am only version %s. "
 571                                                         "You can get a newer version from http://0install.net" %
 572                                                         (min_injector_version, version))
 573
 574                 for x in feed_element.childNodes:
 575                         if x.uri != XMLNS_IFACE:
 576                                 self.metadata.append(x)
 577                                 continue
 578                         if x.name == 'name':
 579                                 self.name = x.content
 580                         elif x.name == 'description':
 581                                 self.description = x.content
 582                         elif x.name == 'summary':
 583                                 self.summary = x.content
 584                         elif x.name == 'feed-for':
 585                                 feed_iface = x.getAttribute('interface')
 586                                 if not feed_iface:
 587                                         raise InvalidInterface('Missing "interface" attribute in <feed-for>')
 588                                 self.feed_for.add(feed_iface)
 589                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
 590                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
 591                                 # in case it happens again.
 592                                 debug("Is feed-for %s", feed_iface)
 593                         elif x.name == 'feed':
 594                                 feed_src = x.getAttribute('src')
 595                                 if not feed_src:
 596                                         raise InvalidInterface('Missing "src" attribute in <feed>')
 597                                 if feed_src.startswith('http:') or local_path:
 598                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = x.getAttribute('langs')))
 599                                 else:
 600                                         raise InvalidInterface("Invalid feed URL '%s'" % feed_src)
 601                         else:
 602                                 self.metadata.append(x)
 603
 604                 if not self.name:
 605                         raise InvalidInterface("Missing <name> in feed")
 606                 if not self.summary:
 607                         raise InvalidInterface("Missing <summary> in feed")
 608
 609                 def process_group(group, group_attrs, base_depends, base_bindings):
 610                         for item in group.childNodes:
 611                                 if item.uri != XMLNS_IFACE: continue
 612
 613                                 if item.name not in ('group', 'implementation', 'package-implementation'):
 614                                         continue
 615
 616                                 depends = base_depends[:]
 617                                 bindings = base_bindings[:]
 618
 619                                 item_attrs = _merge_attrs(group_attrs, item)
 620
 621                                 # We've found a group or implementation. Scan for dependencies
 622                                 # and bindings. Doing this here means that:
 623                                 # - We can share the code for groups and implementations here.
 624                                 # - The order doesn't matter, because these get processed first.
 625                                 # A side-effect is that the document root cannot contain
 626                                 # these.
 627                                 for child in item.childNodes:
 628                                         if child.uri != XMLNS_IFACE: continue
 629                                         if child.name == 'requires':
 630                                                 dep = process_depends(child)
 631                                                 depends.append(dep)
 632                                         elif child.name in binding_names:
 633                                                 bindings.append(process_binding(child))
 634
 635                                 if item.name == 'group':
 636                                         process_group(item, item_attrs, depends, bindings)
 637                                 elif item.name == 'implementation':
 638                                         process_impl(item, item_attrs, depends, bindings)
 639                                 elif item.name == 'package-implementation':
 640                                         process_native_impl(item, item_attrs, depends)
 641                                 else:
 642                                         assert 0
 643
 644                 def process_impl(item, item_attrs, depends, bindings):
 645                         id = item.getAttribute('id')
 646                         if id is None:
 647                                 raise InvalidInterface("Missing 'id' attribute on %s" % item)
 648                         if local_dir and (id.startswith('/') or id.startswith('.')):
 649                                 impl = self._get_impl(os.path.abspath(os.path.join(local_dir, id)))
 650                         else:
 651                                 if '=' not in id:
 652                                         raise InvalidInterface('Invalid "id"; form is "alg=value" (got "%s")' % id)
 653                                 alg, sha1 = id.split('=')
 654                                 try:
 655                                         long(sha1, 16)
 656                                 except Exception, ex:
 657                                         raise InvalidInterface('Bad SHA1 attribute: %s' % ex)
 658                                 impl = self._get_impl(id)
 659
 660                         impl.metadata = item_attrs
 661                         try:
 662                                 version_mod = item_attrs.get('version-modifier', None)
 663                                 if version_mod:
 664                                         item_attrs['version'] += version_mod
 665                                         del item_attrs['version-modifier']
 666                                 version = item_attrs['version']
 667                         except KeyError:
 668                                 raise InvalidInterface("Missing version attribute")
 669                         impl.version = parse_version(version)
 670
 671                         item_main = item_attrs.get('main', None)
 672                         if item_main and item_main.startswith('/'):
 673                                 raise InvalidInterface("'main' attribute must be relative, but '%s' starts with '/'!" %
 674                                                         item_main)
 675                         impl.main = item_main
 676
 677                         impl.released = item_attrs.get('released', None)
 678                         impl.langs = item_attrs.get('langs', None)
 679
 680                         size = item.getAttribute('size')
 681                         if size:
 682                                 impl.size = long(size)
 683                         impl.arch = item_attrs.get('arch', None)
 684                         try:
 685                                 stability = stability_levels[str(item_attrs['stability'])]
 686                         except KeyError:
 687                                 stab = str(item_attrs['stability'])
 688                                 if stab != stab.lower():
 689                                         raise InvalidInterface('Stability "%s" invalid - use lower case!' % item_attrs.stability)
 690                                 raise InvalidInterface('Stability "%s" invalid' % item_attrs['stability'])
 691                         if stability >= preferred:
 692                                 raise InvalidInterface("Upstream can't set stability to preferred!")
 693                         impl.upstream_stability = stability
 694
 695                         impl.bindings = bindings
 696                         impl.requires = depends
 697
 698                         for elem in item.childNodes:
 699                                 if elem.uri != XMLNS_IFACE: continue
 700                                 if elem.name == 'archive':
 701                                         url = elem.getAttribute('href')
 702                                         if not url:
 703                                                 raise InvalidInterface("Missing href attribute on <archive>")
 704                                         size = elem.getAttribute('size')
 705                                         if not size:
 706                                                 raise InvalidInterface("Missing size attribute on <archive>")
 707                                         impl.add_download_source(url = url, size = long(size),
 708                                                         extract = elem.getAttribute('extract'),
 709                                                         start_offset = _get_long(elem, 'start-offset'),
 710                                                         type = elem.getAttribute('type'))
 711                                 elif elem.name == 'recipe':
 712                                         recipe = Recipe()
 713                                         for recipe_step in elem.childNodes:
 714                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
 715                                                         url = recipe_step.getAttribute('href')
 716                                                         if not url:
 717                                                                 raise InvalidInterface("Missing href attribute on <archive>")
 718                                                         size = recipe_step.getAttribute('size')
 719                                                         if not size:
 720                                                                 raise InvalidInterface("Missing size attribute on <archive>")
 721                                                         recipe.steps.append(DownloadSource(None, url = url, size = long(size),
 722                                                                         extract = recipe_step.getAttribute('extract'),
 723                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
 724                                                                         type = recipe_step.getAttribute('type')))
 725                                                 else:
 726                                                         info("Unknown step '%s' in recipe; skipping recipe", recipe_step.name)
 727                                                         break
 728                                         else:
 729                                                 impl.download_sources.append(recipe)
 730
 731                 def process_native_impl(item, item_attrs, depends):
 732                         package = item_attrs.get('package', None)
 733                         if package is None:
 734                                 raise InvalidInterface("Missing 'package' attribute on %s" % item)
 735
 736                         def factory(id):
 737                                 assert id.startswith('package:')
 738                                 impl = self._get_impl(id)
 739
 740                                 impl.metadata = item_attrs
 741
 742                                 item_main = item_attrs.get('main', None)
 743                                 if item_main and not item_main.startswith('/'):
 744                                         raise InvalidInterface("'main' attribute must be absolute, but '%s' doesn't start with '/'!" %
 745                                                                 item_main)
 746                                 impl.main = item_main
 747                                 impl.upstream_stability = packaged
 748                                 impl.requires = depends
 749
 750                                 return impl
 751
 752                         distro.get_package_info(package, factory)
 753
 754                 root_attrs = {'stability': 'testing'}
 755                 if main:
 756                         root_attrs['main'] = main
 757                 process_group(feed_element, root_attrs, [], [])
 758
 759         def get_name(self):
 760                 return self.name or '(' + os.path.basename(self.url) + ')'
 761
 762         def __repr__(self):
 763                 return "<Feed %s>" % self.url
 764
 765         def _get_impl(self, id):
 766                 if id not in self.implementations:
 767                         if id.startswith('package:'):
 768                                 impl = DistributionImplementation(self, id)
 769                         else:
 770                                 impl = ZeroInstallImplementation(self, id)
 771                         self.implementations[id] = impl
 772                 return self.implementations[id]
 773
 774         def set_stability_policy(self, new):
 775                 assert new is None or isinstance(new, Stability)
 776                 self.stability_policy = new
 777
 778         def get_feed(self, url):
 779                 for x in self.feeds:
 780                         if x.uri == url:
 781                                 return x
 782                 return None
 783
 784         def add_metadata(self, elem):
 785                 self.metadata.append(elem)
 786
 787         def get_metadata(self, uri, name):
 788                 """Return a list of interface metadata elements with this name and namespace URI."""
 789                 return [m for m in self.metadata if m.name == name and m.uri == uri]
 790
 791 class DummyFeed(object):
 792         """Temporary class used during API transition."""
 793         last_modified = None
 794         name = '-'
 795         last_checked = property(lambda self: None)
 796         implementations = property(lambda self: {})
 797         feeds = property(lambda self: [])
 798         summary = property(lambda self: '-')
 799         description = property(lambda self: '')
 800         def get_name(self): return self.name
 801         def get_feed(self, url): return None
 802         def get_metadata(self, uri, name): return []
 803 _dummy_feed = DummyFeed()
 804
 805 def unescape(uri):
 806         """Convert each %20 to a space, etc.
 807         @rtype: str"""
 808         uri = uri.replace('#', '/')
 809         if '%' not in uri: return uri
 810         return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
 811                 lambda match: chr(int(match.group(0)[1:], 16)),
 812                 uri).decode('utf-8')
 813
 814 def escape(uri):
 815         """Convert each space to %20, etc
 816         @rtype: str"""
 817         return re.sub('[^-_.a-zA-Z0-9]',
 818                 lambda match: '%%%02x' % ord(match.group(0)),
 819                 uri.encode('utf-8'))
 820
 821 def _pretty_escape(uri):
 822         """Convert each space to %20, etc
 823         : is preserved and / becomes #. This makes for nicer strings,
 824         and may replace L{escape} everywhere in future.
 825         @rtype: str"""
 826         return re.sub('[^-_.a-zA-Z0-9:/]',
 827                 lambda match: '%%%02x' % ord(match.group(0)),
 828                 uri.encode('utf-8')).replace('/', '#')
 829
 830 def canonical_iface_uri(uri):
 831         """If uri is a relative path, convert to an absolute one.
 832         A "file:///foo" URI is converted to "/foo".
 833         Otherwise, return it unmodified.
 834         @rtype: str
 835         @raise SafeException: if uri isn't valid
 836         """
 837         if uri.startswith('http://'):
 838                 if uri.find("/", 7) == -1:
 839                         raise SafeException("Missing / after hostname in URI '%s'" % uri)
 840                 return uri
 841         elif uri.startswith('file:///'):
 842                 return uri[7:]
 843         else:
 844                 iface_uri = os.path.realpath(uri)
 845                 if os.path.isfile(iface_uri):
 846                         return iface_uri
 847         raise SafeException("Bad interface name '%s'.\n"
 848                         "(doesn't start with 'http:', and "
 849                         "doesn't exist as a local file '%s' either)" %
 850                         (uri, iface_uri))
 851
 852 _version_mod_to_value = {
 853         'pre': -2,
 854         'rc': -1,
 855         '': 0,
 856         'post': 1,
 857 }
 858
 859 # Reverse mapping
 860 _version_value_to_mod = {}
 861 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
 862 del x
 863
 864 _version_re = re.compile('-([a-z]*)')
 865
 866 def parse_version(version_string):
 867         """Convert a version string to an internal representation.
 868         The parsed format can be compared quickly using the standard Python functions.
 869          - Version := DottedList ("-" Mod DottedList?)*
 870          - DottedList := (Integer ("." Integer)*)
 871         @rtype: tuple (opaque)
 872         @raise SafeException: if the string isn't a valid version
 873         @since: 0.24 (moved from L{reader}, from where it is still available):"""
 874         if version_string is None: return None
 875         parts = _version_re.split(version_string)
 876         if parts[-1] == '':
 877                 del parts[-1]   # Ends with a modifier
 878         else:
 879                 parts.append('')
 880         if not parts:
 881                 raise SafeException("Empty version string!")
 882         l = len(parts)
 883         try:
 884                 for x in range(0, l, 2):
 885                         part = parts[x]
 886                         if part:
 887                                 parts[x] = map(int, parts[x].split('.'))
 888                         else:
 889                                 parts[x] = []   # (because ''.split('.') == [''], not [])
 890                 for x in range(1, l, 2):
 891                         parts[x] = _version_mod_to_value[parts[x]]
 892                 return parts
 893         except ValueError, ex:
 894                 raise SafeException("Invalid version format in '%s': %s" % (version_string, ex))
 895         except KeyError, ex:
 896                 raise SafeException("Invalid version modifier in '%s': %s" % (version_string, ex))
 897
 898 def format_version(version):
 899         """Format a parsed version for display. Undoes the effect of L{parse_version}.
 900         @see: L{Implementation.get_version}
 901         @rtype: str
 902         @since: 0.24"""
 903         version = version[:]
 904         l = len(version)
 905         for x in range(0, l, 2):
 906                 version[x] = '.'.join(map(str, version[x]))
 907         for x in range(1, l, 2):
 908                 version[x] = '-' + _version_value_to_mod[version[x]]
 909         if version[-1] == '-': del version[-1]
 910         return ''.join(version)
 911