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 from zeroinstall import _, logger
  17 import os, re, locale, sys
  18 from zeroinstall import SafeException, version
  19 from zeroinstall.injector.namespaces import XMLNS_IFACE
  20 from zeroinstall.injector import qdom
  21 from zeroinstall import support, zerostore
  22
  23 # Element names for bindings in feed files
  24 binding_names = frozenset(['environment', 'overlay', 'executable-in-path', 'executable-in-var'])
  25
  26 _dependency_names = frozenset(['requires', 'restricts'])
  27
  28 network_offline = 'off-line'
  29 network_minimal = 'minimal'
  30 network_full = 'full'
  31 network_levels = (network_offline, network_minimal, network_full)
  32
  33 stability_levels = {}   # Name -> Stability
  34
  35 defaults = {
  36         'PATH': '/bin:/usr/bin',
  37         'XDG_CONFIG_DIRS': '/etc/xdg',
  38         'XDG_DATA_DIRS': '/usr/local/share:/usr/share',
  39 }
  40
  41 class InvalidInterface(SafeException):
  42         """Raised when parsing an invalid feed."""
  43         feed_url = None
  44
  45         def __init__(self, message, ex = None):
  46                 if ex:
  47                         try:
  48                                 message += "\n\n(exact error: %s)" % ex
  49                         except:
  50                                 # Some Python messages have type str but contain UTF-8 sequences.
  51                                 # (e.g. IOException). Adding these to a Unicode 'message' (e.g.
  52                                 # after gettext translation) will cause an error.
  53                                 import codecs
  54                                 decoder = codecs.lookup('utf-8')
  55                                 decex = decoder.decode(str(ex), errors = 'replace')[0]
  56                                 message += "\n\n(exact error: %s)" % decex
  57
  58                 SafeException.__init__(self, message)
  59
  60         def __unicode__(self):
  61                 if hasattr(SafeException, '__unicode__'):
  62                         # Python >= 2.6
  63                         if self.feed_url:
  64                                 return _('%s [%s]') % (SafeException.__unicode__(self), self.feed_url)
  65                         return SafeException.__unicode__(self)
  66                 else:
  67                         return support.unicode(SafeException.__str__(self))
  68
  69 def _split_arch(arch):
  70         """Split an arch into an (os, machine) tuple. Either or both parts may be None."""
  71         if not arch:
  72                 return None, None
  73         elif '-' not in arch:
  74                 raise SafeException(_("Malformed arch '%s'") % arch)
  75         else:
  76                 osys, machine = arch.split('-', 1)
  77                 if osys == '*': osys = None
  78                 if machine == '*': machine = None
  79                 return osys, machine
  80
  81 def _join_arch(osys, machine):
  82         if osys == machine == None: return None
  83         return "%s-%s" % (osys or '*', machine or '*')
  84
  85 def _best_language_match(options):
  86         (language, encoding) = locale.getlocale()
  87
  88         if language:
  89                 # xml:lang uses '-', while LANG uses '_'
  90                 language = language.replace('_', '-')
  91         else:
  92                 language = 'en-US'
  93
  94         return (options.get(language, None) or                  # Exact match (language+region)
  95                 options.get(language.split('-', 1)[0], None) or # Matching language
  96                 options.get('en', None))                        # English
  97
  98 class Stability(object):
  99         """A stability rating. Each implementation has an upstream stability rating and,
 100         optionally, a user-set rating."""
 101         __slots__ = ['level', 'name', 'description']
 102         def __init__(self, level, name, description):
 103                 self.level = level
 104                 self.name = name
 105                 self.description = description
 106                 assert name not in stability_levels
 107                 stability_levels[name] = self
 108
 109         def __cmp__(self, other):
 110                 return cmp(self.level, other.level)
 111
 112         def __lt__(self, other):
 113                 if isinstance(other, Stability):
 114                         return self.level < other.level
 115                 else:
 116                         return NotImplemented
 117
 118         def __eq__(self, other):
 119                 if isinstance(other, Stability):
 120                         return self.level == other.level
 121                 else:
 122                         return NotImplemented
 123
 124         def __str__(self):
 125                 return self.name
 126
 127         def __repr__(self):
 128                 return _("<Stability: %s>") % self.description
 129
 130 def process_binding(e):
 131         """Internal"""
 132         if e.name == 'environment':
 133                 mode = {
 134                         None: EnvironmentBinding.PREPEND,
 135                         'prepend': EnvironmentBinding.PREPEND,
 136                         'append': EnvironmentBinding.APPEND,
 137                         'replace': EnvironmentBinding.REPLACE,
 138                 }[e.getAttribute('mode')]
 139
 140                 binding = EnvironmentBinding(e.getAttribute('name'),
 141                                              insert = e.getAttribute('insert'),
 142                                              default = e.getAttribute('default'),
 143                                              value = e.getAttribute('value'),
 144                                              mode = mode,
 145                                              separator = e.getAttribute('separator'))
 146                 if not binding.name: raise InvalidInterface(_("Missing 'name' in binding"))
 147                 if binding.insert is None and binding.value is None:
 148                         raise InvalidInterface(_("Missing 'insert' or 'value' in binding"))
 149                 if binding.insert is not None and binding.value is not None:
 150                         raise InvalidInterface(_("Binding contains both 'insert' and 'value'"))
 151                 return binding
 152         elif e.name == 'executable-in-path':
 153                 return ExecutableBinding(e, in_path = True)
 154         elif e.name == 'executable-in-var':
 155                 return ExecutableBinding(e, in_path = False)
 156         elif e.name == 'overlay':
 157                 return OverlayBinding(e.getAttribute('src'), e.getAttribute('mount-point'))
 158         else:
 159                 raise Exception(_("Unknown binding type '%s'") % e.name)
 160
 161 def process_depends(item, local_feed_dir):
 162         """Internal"""
 163         # Note: also called from selections
 164         attrs = item.attrs
 165         dep_iface = item.getAttribute('interface')
 166         if not dep_iface:
 167                 raise InvalidInterface(_("Missing 'interface' on <%s>") % item.name)
 168         if dep_iface.startswith('.'):
 169                 if local_feed_dir:
 170                         dep_iface = os.path.abspath(os.path.join(local_feed_dir, dep_iface))
 171                         # (updates the element too, in case we write it out again)
 172                         attrs['interface'] = dep_iface
 173                 else:
 174                         raise InvalidInterface(_('Relative interface URI "%s" in non-local feed') % dep_iface)
 175
 176         if item.name == 'restricts':
 177                 dependency = InterfaceRestriction(dep_iface, element = item)
 178         else:
 179                 dependency = InterfaceDependency(dep_iface, element = item)
 180
 181         for e in item.childNodes:
 182                 if e.uri != XMLNS_IFACE: continue
 183                 if e.name in binding_names:
 184                         dependency.bindings.append(process_binding(e))
 185                 elif e.name == 'version':
 186                         dependency.restrictions.append(
 187                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 188                                                         before = parse_version(e.getAttribute('before'))))
 189         return dependency
 190
 191 def N_(message): return message
 192
 193 insecure = Stability(0, N_('insecure'), _('This is a security risk'))
 194 buggy = Stability(5, N_('buggy'), _('Known to have serious bugs'))
 195 developer = Stability(10, N_('developer'), _('Work-in-progress - bugs likely'))
 196 testing = Stability(20, N_('testing'), _('Stability unknown - please test!'))
 197 stable = Stability(30, N_('stable'), _('Tested - no serious problems found'))
 198 packaged = Stability(35, N_('packaged'), _('Supplied by the local package manager'))
 199 preferred = Stability(40, N_('preferred'), _('Best of all - must be set manually'))
 200
 201 del N_
 202
 203 class Restriction(object):
 204         """A Restriction limits the allowed implementations of an Interface."""
 205         __slots__ = []
 206
 207         def meets_restriction(self, impl):
 208                 """Called by the L{solver.Solver} to check whether a particular implementation is acceptable.
 209                 @return: False if this implementation is not a possibility
 210                 @rtype: bool
 211                 """
 212                 raise NotImplementedError(_("Abstract"))
 213
 214 class VersionRestriction(Restriction):
 215         """Only select implementations with a particular version number.
 216         @since: 0.40"""
 217
 218         def __init__(self, version):
 219                 """@param version: the required version number
 220                 @see: L{parse_version}; use this to pre-process the version number
 221                 """
 222                 self.version = version
 223
 224         def meets_restriction(self, impl):
 225                 return impl.version == self.version
 226
 227         def __str__(self):
 228                 return _("(restriction: version = %s)") % format_version(self.version)
 229
 230 class VersionRangeRestriction(Restriction):
 231         """Only versions within the given range are acceptable"""
 232         __slots__ = ['before', 'not_before']
 233
 234         def __init__(self, before, not_before):
 235                 """@param before: chosen versions must be earlier than this
 236                 @param not_before: versions must be at least this high
 237                 @see: L{parse_version}; use this to pre-process the versions
 238                 """
 239                 self.before = before
 240                 self.not_before = not_before
 241
 242         def meets_restriction(self, impl):
 243                 if self.not_before and impl.version < self.not_before:
 244                         return False
 245                 if self.before and impl.version >= self.before:
 246                         return False
 247                 return True
 248
 249         def __str__(self):
 250                 if self.not_before is not None or self.before is not None:
 251                         range = ''
 252                         if self.not_before is not None:
 253                                 range += format_version(self.not_before) + ' <= '
 254                         range += 'version'
 255                         if self.before is not None:
 256                                 range += ' < ' + format_version(self.before)
 257                 else:
 258                         range = 'none'
 259                 return _("(restriction: %s)") % range
 260
 261 class Binding(object):
 262         """Information about how the choice of a Dependency is made known
 263         to the application being run."""
 264
 265         @property
 266         def command(self):
 267                 """"Returns the name of the specific command needed by this binding, if any.
 268                 @since: 1.2"""
 269                 return None
 270
 271 class EnvironmentBinding(Binding):
 272         """Indicate the chosen implementation using an environment variable."""
 273         __slots__ = ['name', 'insert', 'default', 'mode', 'value']
 274
 275         PREPEND = 'prepend'
 276         APPEND = 'append'
 277         REPLACE = 'replace'
 278
 279         def __init__(self, name, insert, default = None, mode = PREPEND, value=None, separator=None):
 280                 """
 281                 mode argument added in version 0.28
 282                 value argument added in version 0.52
 283                 """
 284                 self.name = name
 285                 self.insert = insert
 286                 self.default = default
 287                 self.mode = mode
 288                 self.value = value
 289                 if separator is None:
 290                         self.separator = os.pathsep
 291                 else:
 292                         self.separator = separator
 293
 294
 295         def __str__(self):
 296                 return _("<environ %(name)s %(mode)s %(insert)s %(value)s>") % \
 297                         {'name': self.name, 'mode': self.mode, 'insert': self.insert, 'value': self.value}
 298
 299         __repr__ = __str__
 300
 301         def get_value(self, path, old_value):
 302                 """Calculate the new value of the environment variable after applying this binding.
 303                 @param path: the path to the selected implementation
 304                 @param old_value: the current value of the environment variable
 305                 @return: the new value for the environment variable"""
 306
 307                 if self.insert is not None:
 308                         extra = os.path.join(path, self.insert)
 309                 else:
 310                         assert self.value is not None
 311                         extra = self.value
 312
 313                 if self.mode == EnvironmentBinding.REPLACE:
 314                         return extra
 315
 316                 if old_value is None:
 317                         old_value = self.default or defaults.get(self.name, None)
 318                 if old_value is None:
 319                         return extra
 320                 if self.mode == EnvironmentBinding.PREPEND:
 321                         return extra + self.separator + old_value
 322                 else:
 323                         return old_value + self.separator + extra
 324
 325         def _toxml(self, doc, prefixes):
 326                 """Create a DOM element for this binding.
 327                 @param doc: document to use to create the element
 328                 @return: the new element
 329                 """
 330                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 331                 env_elem.setAttributeNS(None, 'name', self.name)
 332                 if self.mode is not None:
 333                         env_elem.setAttributeNS(None, 'mode', self.mode)
 334                 if self.insert is not None:
 335                         env_elem.setAttributeNS(None, 'insert', self.insert)
 336                 else:
 337                         env_elem.setAttributeNS(None, 'value', self.value)
 338                 if self.default:
 339                         env_elem.setAttributeNS(None, 'default', self.default)
 340                 if self.separator:
 341                         env_elem.setAttributeNS(None, 'separator', self.separator)
 342                 return env_elem
 343
 344 class ExecutableBinding(Binding):
 345         """Make the chosen command available in $PATH.
 346         @ivar in_path: True to add the named command to $PATH, False to store in named variable
 347         @type in_path: bool
 348         """
 349         __slots__ = ['qdom']
 350
 351         def __init__(self, qdom, in_path):
 352                 self.qdom = qdom
 353                 self.in_path = in_path
 354
 355         def __str__(self):
 356                 return str(self.qdom)
 357
 358         __repr__ = __str__
 359
 360         def _toxml(self, doc, prefixes):
 361                 return self.qdom.toDOM(doc, prefixes)
 362
 363         @property
 364         def name(self):
 365                 return self.qdom.getAttribute('name')
 366
 367         @property
 368         def command(self):
 369                 return self.qdom.getAttribute("command") or 'run'
 370
 371 class OverlayBinding(Binding):
 372         """Make the chosen implementation available by overlaying it onto another part of the file-system.
 373         This is to support legacy programs which use hard-coded paths."""
 374         __slots__ = ['src', 'mount_point']
 375
 376         def __init__(self, src, mount_point):
 377                 self.src = src
 378                 self.mount_point = mount_point
 379
 380         def __str__(self):
 381                 return _("<overlay %(src)s on %(mount_point)s>") % {'src': self.src or '.', 'mount_point': self.mount_point or '/'}
 382
 383         __repr__ = __str__
 384
 385         def _toxml(self, doc, prefixes):
 386                 """Create a DOM element for this binding.
 387                 @param doc: document to use to create the element
 388                 @return: the new element
 389                 """
 390                 env_elem = doc.createElementNS(XMLNS_IFACE, 'overlay')
 391                 if self.src is not None:
 392                         env_elem.setAttributeNS(None, 'src', self.src)
 393                 if self.mount_point is not None:
 394                         env_elem.setAttributeNS(None, 'mount-point', self.mount_point)
 395                 return env_elem
 396
 397 class Feed(object):
 398         """An interface's feeds are other interfaces whose implementations can also be
 399         used as implementations of this interface."""
 400         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs', 'site_package']
 401         def __init__(self, uri, arch, user_override, langs = None, site_package = False):
 402                 self.uri = uri
 403                 # This indicates whether the feed comes from the user's overrides
 404                 # file. If true, writer.py will write it when saving.
 405                 self.user_override = user_override
 406                 self.os, self.machine = _split_arch(arch)
 407                 self.langs = langs
 408                 self.site_package = site_package
 409
 410         def __str__(self):
 411                 return "<Feed from %s>" % self.uri
 412         __repr__ = __str__
 413
 414         arch = property(lambda self: _join_arch(self.os, self.machine))
 415
 416 class Dependency(object):
 417         """A Dependency indicates that an Implementation requires some additional
 418         code to function. This is an abstract base class.
 419         @ivar qdom: the XML element for this Dependency (since 0launch 0.51)
 420         @type qdom: L{qdom.Element}
 421         @ivar metadata: any extra attributes from the XML element
 422         @type metadata: {str: str}
 423         """
 424         __slots__ = ['qdom']
 425
 426         Essential = "essential"         # Must select a version of the dependency
 427         Recommended = "recommended"     # Prefer to select a version
 428         Restricts = "restricts"         # Just adds restrictions without expressing any opinion
 429
 430         def __init__(self, element):
 431                 assert isinstance(element, qdom.Element), type(element) # Use InterfaceDependency instead!
 432                 self.qdom = element
 433
 434         @property
 435         def metadata(self):
 436                 return self.qdom.attrs
 437
 438         def get_required_commands(self):
 439                 """Return a list of command names needed by this dependency"""
 440                 return []
 441
 442 class InterfaceRestriction(Dependency):
 443         """A Dependency that restricts the possible choices of a Zero Install interface.
 444         @ivar interface: the interface required by this dependency
 445         @type interface: str
 446         @ivar restrictions: a list of constraints on acceptable implementations
 447         @type restrictions: [L{Restriction}]
 448         @since: 1.10
 449         """
 450         __slots__ = ['interface', 'restrictions']
 451
 452         def __init__(self, interface, restrictions = None, element = None):
 453                 Dependency.__init__(self, element)
 454                 assert isinstance(interface, (str, support.unicode))
 455                 assert interface
 456                 self.interface = interface
 457                 if restrictions is None:
 458                         self.restrictions = []
 459                 else:
 460                         self.restrictions = restrictions
 461
 462         importance = Dependency.Restricts
 463         bindings = ()
 464
 465         def __str__(self):
 466                 return _("<Restriction on %(interface)s; %(restrictions)s>") % {'interface': self.interface, 'restrictions': self.restrictions}
 467
 468 class InterfaceDependency(InterfaceRestriction):
 469         """A Dependency on a Zero Install interface.
 470         @ivar interface: the interface required by this dependency
 471         @type interface: str
 472         @ivar restrictions: a list of constraints on acceptable implementations
 473         @type restrictions: [L{Restriction}]
 474         @ivar bindings: how to make the choice of implementation known
 475         @type bindings: [L{Binding}]
 476         @since: 0.28
 477         """
 478         __slots__ = ['bindings']
 479
 480         def __init__(self, interface, restrictions = None, element = None):
 481                 InterfaceRestriction.__init__(self, interface, restrictions, element)
 482                 self.bindings = []
 483
 484         def __str__(self):
 485                 return _("<Dependency on %(interface)s; bindings: %(bindings)s%(restrictions)s>") % {'interface': self.interface, 'bindings': self.bindings, 'restrictions': self.restrictions}
 486
 487         @property
 488         def importance(self):
 489                 return self.qdom.getAttribute("importance") or Dependency.Essential
 490
 491         def get_required_commands(self):
 492                 """Return a list of command names needed by this dependency"""
 493                 if self.qdom.name == 'runner':
 494                         commands = [self.qdom.getAttribute('command') or 'run']
 495                 else:
 496                         commands = []
 497                 for b in self.bindings:
 498                         c = b.command
 499                         if c is not None:
 500                                 commands.append(c)
 501                 return commands
 502
 503         @property
 504         def command(self):
 505                 if self.qdom.name == 'runner':
 506                         return self.qdom.getAttribute('command') or 'run'
 507                 return None
 508
 509 class RetrievalMethod(object):
 510         """A RetrievalMethod provides a way to fetch an implementation."""
 511         __slots__ = []
 512
 513 class DownloadSource(RetrievalMethod):
 514         """A DownloadSource provides a way to fetch an implementation."""
 515         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 516
 517         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 518                 self.implementation = implementation
 519                 self.url = url
 520                 self.size = size
 521                 self.extract = extract
 522                 self.start_offset = start_offset
 523                 self.type = type                # MIME type - see unpack.py
 524
 525 class RenameStep(RetrievalMethod):
 526         """A Rename provides a way to rename / move a file within an implementation."""
 527         __slots__ = ['source', 'dest']
 528
 529         def __init__(self, source, dest):
 530                 self.source = source
 531                 self.dest = dest
 532
 533 class Recipe(RetrievalMethod):
 534         """Get an implementation by following a series of steps.
 535         @ivar size: the combined download sizes from all the steps
 536         @type size: int
 537         @ivar steps: the sequence of steps which must be performed
 538         @type steps: [L{RetrievalMethod}]"""
 539         __slots__ = ['steps']
 540
 541         def __init__(self):
 542                 self.steps = []
 543
 544         size = property(lambda self: sum([x.size for x in self.steps if isinstance(x, DownloadSource)]))
 545
 546 class DistributionSource(RetrievalMethod):
 547         """A package that is installed using the distribution's tools (including PackageKit).
 548         @ivar install: a function to call to install this package
 549         @type install: (L{handler.Handler}) -> L{tasks.Blocker}
 550         @ivar package_id: the package name, in a form recognised by the distribution's tools
 551         @type package_id: str
 552         @ivar size: the download size in bytes
 553         @type size: int
 554         @ivar needs_confirmation: whether the user should be asked to confirm before calling install()
 555         @type needs_confirmation: bool"""
 556
 557         __slots__ = ['package_id', 'size', 'install', 'needs_confirmation']
 558
 559         def __init__(self, package_id, size, install, needs_confirmation = True):
 560                 RetrievalMethod.__init__(self)
 561                 self.package_id = package_id
 562                 self.size = size
 563                 self.install = install
 564                 self.needs_confirmation = needs_confirmation
 565
 566 class Command(object):
 567         """A Command is a way of running an Implementation as a program."""
 568
 569         __slots__ = ['qdom', '_depends', '_local_dir', '_runner', '_bindings']
 570
 571         def __init__(self, qdom, local_dir):
 572                 """@param qdom: the <command> element
 573                 @param local_dir: the directory containing the feed (for relative dependencies), or None if not local
 574                 """
 575                 assert qdom.name == 'command', 'not <command>: %s' % qdom
 576                 self.qdom = qdom
 577                 self._local_dir = local_dir
 578                 self._depends = None
 579                 self._bindings = None
 580
 581         path = property(lambda self: self.qdom.attrs.get("path", None))
 582
 583         def _toxml(self, doc, prefixes):
 584                 return self.qdom.toDOM(doc, prefixes)
 585
 586         @property
 587         def requires(self):
 588                 if self._depends is None:
 589                         self._runner = None
 590                         depends = []
 591                         for child in self.qdom.childNodes:
 592                                 if child.name in _dependency_names:
 593                                         dep = process_depends(child, self._local_dir)
 594                                         depends.append(dep)
 595                                 elif child.name == 'runner':
 596                                         if self._runner:
 597                                                 raise InvalidInterface(_("Multiple <runner>s in <command>!"))
 598                                         dep = process_depends(child, self._local_dir)
 599                                         depends.append(dep)
 600                                         self._runner = dep
 601                         self._depends = depends
 602                 return self._depends
 603
 604         def get_runner(self):
 605                 self.requires           # (sets _runner)
 606                 return self._runner
 607
 608         def __str__(self):
 609                 return str(self.qdom)
 610
 611         @property
 612         def bindings(self):
 613                 """@since: 1.3"""
 614                 if self._bindings is None:
 615                         bindings = []
 616                         for e in self.qdom.childNodes:
 617                                 if e.uri != XMLNS_IFACE: continue
 618                                 if e.name in binding_names:
 619                                         bindings.append(process_binding(e))
 620                         self._bindings = bindings
 621                 return self._bindings
 622
 623 class Implementation(object):
 624         """An Implementation is a package which implements an Interface.
 625         @ivar download_sources: list of methods of getting this implementation
 626         @type download_sources: [L{RetrievalMethod}]
 627         @ivar feed: the feed owning this implementation (since 0.32)
 628         @type feed: [L{ZeroInstallFeed}]
 629         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 630         @type bindings: [Binding]
 631         @ivar upstream_stability: the stability reported by the packager
 632         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged]
 633         @ivar user_stability: the stability as set by the user
 634         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged | preferred]
 635         @ivar langs: natural languages supported by this package
 636         @type langs: str
 637         @ivar requires: interfaces this package depends on
 638         @type requires: [L{Dependency}]
 639         @ivar commands: ways to execute as a program
 640         @type commands: {str: Command}
 641         @ivar metadata: extra metadata from the feed
 642         @type metadata: {"[URI ]localName": str}
 643         @ivar id: a unique identifier for this Implementation
 644         @ivar version: a parsed version number
 645         @ivar released: release date
 646         @ivar local_path: the directory containing this local implementation, or None if it isn't local (id isn't a path)
 647         @type local_path: str | None
 648         @ivar requires_root_install: whether the user will need admin rights to use this
 649         @type requires_root_install: bool
 650         """
 651
 652         # Note: user_stability shouldn't really be here
 653
 654         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 655                      'requires', 'metadata', 'download_sources', 'commands',
 656                      'id', 'feed', 'version', 'released', 'bindings', 'machine']
 657
 658         def __init__(self, feed, id):
 659                 assert id
 660                 self.feed = feed
 661                 self.id = id
 662                 self.user_stability = None
 663                 self.upstream_stability = None
 664                 self.metadata = {}      # [URI + " "] + localName -> value
 665                 self.requires = []
 666                 self.version = None
 667                 self.released = None
 668                 self.download_sources = []
 669                 self.langs = ""
 670                 self.machine = None
 671                 self.bindings = []
 672                 self.commands = {}
 673
 674         def get_stability(self):
 675                 return self.user_stability or self.upstream_stability or testing
 676
 677         def __str__(self):
 678                 return self.id
 679
 680         def __repr__(self):
 681                 return "v%s (%s)" % (self.get_version(), self.id)
 682
 683         def __cmp__(self, other):
 684                 """Newer versions come first"""
 685                 d = cmp(other.version, self.version)
 686                 if d: return d
 687                 # If the version number is the same, just give a stable sort order, and
 688                 # ensure that two different implementations don't compare equal.
 689                 d = cmp(other.feed.url, self.feed.url)
 690                 if d: return d
 691                 return cmp(other.id, self.id)
 692
 693         def __hash__(self):
 694                 return self.id.__hash__()
 695
 696         def __eq__(self, other):
 697                 return self is other
 698
 699         def __le__(self, other):
 700                 if isinstance(other, Implementation):
 701                         if other.version < self.version: return True
 702                         elif other.version > self.version: return False
 703
 704                         if other.feed.url < self.feed.url: return True
 705                         elif other.feed.url > self.feed.url: return False
 706
 707                         return other.id <= self.id
 708                 else:
 709                         return NotImplemented
 710
 711         def get_version(self):
 712                 """Return the version as a string.
 713                 @see: L{format_version}
 714                 """
 715                 return format_version(self.version)
 716
 717         arch = property(lambda self: _join_arch(self.os, self.machine))
 718
 719         os = None
 720         local_path = None
 721         digests = None
 722         requires_root_install = False
 723
 724         def _get_main(self):
 725                 """"@deprecated: use commands["run"] instead"""
 726                 main = self.commands.get("run", None)
 727                 if main is not None:
 728                         return main.path
 729                 return None
 730         def _set_main(self, path):
 731                 """"@deprecated: use commands["run"] instead"""
 732                 if path is None:
 733                         if "run" in self.commands:
 734                                 del self.commands["run"]
 735                 else:
 736                         self.commands["run"] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': path, 'name': 'run'}), None)
 737         main = property(_get_main, _set_main)
 738
 739         def is_available(self, stores):
 740                 """Is this Implementation available locally?
 741                 (a local implementation, an installed distribution package, or a cached ZeroInstallImplementation)
 742                 @rtype: bool
 743                 @since: 0.53
 744                 """
 745                 raise NotImplementedError("abstract")
 746
 747 class DistributionImplementation(Implementation):
 748         """An implementation provided by the distribution. Information such as the version
 749         comes from the package manager.
 750         @ivar package_implementation: the <package-implementation> element that generated this impl (since 1.7)
 751         @type package_implementation: L{qdom.Element}
 752         @since: 0.28"""
 753         __slots__ = ['distro', 'installed', 'package_implementation']
 754
 755         def __init__(self, feed, id, distro, package_implementation = None):
 756                 assert id.startswith('package:')
 757                 Implementation.__init__(self, feed, id)
 758                 self.distro = distro
 759                 self.installed = False
 760                 self.package_implementation = package_implementation
 761
 762                 if package_implementation:
 763                         for child in package_implementation.childNodes:
 764                                 if child.uri != XMLNS_IFACE: continue
 765                                 if child.name == 'command':
 766                                         command_name = child.attrs.get('name', None)
 767                                         if not command_name:
 768                                                 raise InvalidInterface('Missing name for <command>')
 769                                         self.commands[command_name] = Command(child, local_dir = None)
 770
 771         @property
 772         def requires_root_install(self):
 773                 return not self.installed
 774
 775         def is_available(self, stores):
 776                 return self.installed
 777
 778 class ZeroInstallImplementation(Implementation):
 779         """An implementation where all the information comes from Zero Install.
 780         @ivar digests: a list of "algorith=value" or "algorith_value" strings (since 0.45)
 781         @type digests: [str]
 782         @since: 0.28"""
 783         __slots__ = ['os', 'size', 'digests', 'local_path']
 784
 785         def __init__(self, feed, id, local_path):
 786                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 787                 assert not id.startswith('package:'), id
 788                 Implementation.__init__(self, feed, id)
 789                 self.size = None
 790                 self.os = None
 791                 self.digests = []
 792                 self.local_path = local_path
 793
 794         # Deprecated
 795         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 796                                                    if isinstance(x, InterfaceRestriction)]))
 797
 798         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 799                 """Add a download source."""
 800                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 801
 802         def set_arch(self, arch):
 803                 self.os, self.machine = _split_arch(arch)
 804         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 805
 806         def is_available(self, stores):
 807                 if self.local_path is not None:
 808                         return os.path.exists(self.local_path)
 809                 if self.digests:
 810                         path = stores.lookup_maybe(self.digests)
 811                         return path is not None
 812                 return False    # (0compile creates fake entries with no digests)
 813
 814 class Interface(object):
 815         """An Interface represents some contract of behaviour.
 816         @ivar uri: the URI for this interface.
 817         @ivar stability_policy: user's configured policy.
 818         Implementations at this level or higher are preferred.
 819         Lower levels are used only if there is no other choice.
 820         """
 821         __slots__ = ['uri', 'stability_policy', 'extra_feeds']
 822
 823         implementations = property(lambda self: self._main_feed.implementations)
 824         name = property(lambda self: self._main_feed.name)
 825         description = property(lambda self: self._main_feed.description)
 826         summary = property(lambda self: self._main_feed.summary)
 827         last_modified = property(lambda self: self._main_feed.last_modified)
 828         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 829         metadata = property(lambda self: self._main_feed.metadata)
 830
 831         last_checked = property(lambda self: self._main_feed.last_checked)
 832
 833         def __init__(self, uri):
 834                 assert uri
 835                 if uri.startswith('http:') or uri.startswith('https:') or os.path.isabs(uri):
 836                         self.uri = uri
 837                 else:
 838                         raise SafeException(_("Interface name '%s' doesn't start "
 839                                             "with 'http:' or 'https:'") % uri)
 840                 self.reset()
 841
 842         def _get_feed_for(self):
 843                 retval = {}
 844                 for key in self._main_feed.feed_for:
 845                         retval[key] = True
 846                 return retval
 847         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 848
 849         def reset(self):
 850                 self.extra_feeds = []
 851                 self.stability_policy = None
 852
 853         def get_name(self):
 854                 from zeroinstall.injector.iface_cache import iface_cache
 855                 feed = iface_cache.get_feed(self.uri)
 856                 if feed:
 857                         return feed.get_name()
 858                 return '(' + os.path.basename(self.uri) + ')'
 859
 860         def __repr__(self):
 861                 return _("<Interface %s>") % self.uri
 862
 863         def set_stability_policy(self, new):
 864                 assert new is None or isinstance(new, Stability)
 865                 self.stability_policy = new
 866
 867         def get_feed(self, url):
 868                 #import warnings
 869                 #warnings.warn("use iface_cache.get_feed instead", DeprecationWarning, 2)
 870                 for x in self.extra_feeds:
 871                         if x.uri == url:
 872                                 return x
 873                 #return self._main_feed.get_feed(url)
 874                 return None
 875
 876         def get_metadata(self, uri, name):
 877                 return self._main_feed.get_metadata(uri, name)
 878
 879         @property
 880         def _main_feed(self):
 881                 import warnings
 882                 warnings.warn("use the feed instead", DeprecationWarning, 3)
 883                 from zeroinstall.injector import policy
 884                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
 885                 feed = iface_cache.get_feed(self.uri)
 886                 if feed is None:
 887                         return _dummy_feed
 888                 return feed
 889
 890 def _merge_attrs(attrs, item):
 891         """Add each attribute of item to a copy of attrs and return the copy.
 892         @type attrs: {str: str}
 893         @type item: L{qdom.Element}
 894         @rtype: {str: str}
 895         """
 896         new = attrs.copy()
 897         for a in item.attrs:
 898                 new[str(a)] = item.attrs[a]
 899         return new
 900
 901 def _get_long(elem, attr_name):
 902         val = elem.getAttribute(attr_name)
 903         if val is not None:
 904                 try:
 905                         val = int(val)
 906                 except ValueError:
 907                         raise SafeException(_("Invalid value for integer attribute '%(attribute_name)s': %(value)s") % {'attribute_name': attr_name, 'value': val})
 908         return val
 909
 910 class ZeroInstallFeed(object):
 911         """A feed lists available implementations of an interface.
 912         @ivar url: the URL for this feed
 913         @ivar implementations: Implementations in this feed, indexed by ID
 914         @type implementations: {str: L{Implementation}}
 915         @ivar name: human-friendly name
 916         @ivar summaries: short textual description (in various languages, since 0.49)
 917         @type summaries: {str: str}
 918         @ivar descriptions: long textual description (in various languages, since 0.49)
 919         @type descriptions: {str: str}
 920         @ivar last_modified: timestamp on signature
 921         @ivar last_checked: time feed was last successfully downloaded and updated
 922         @ivar local_path: the path of this local feed, or None if remote (since 1.7)
 923         @type local_path: str | None
 924         @ivar feeds: list of <feed> elements in this feed
 925         @type feeds: [L{Feed}]
 926         @ivar feed_for: interfaces for which this could be a feed
 927         @type feed_for: set(str)
 928         @ivar metadata: extra elements we didn't understand
 929         """
 930         # _main is deprecated
 931         __slots__ = ['url', 'implementations', 'name', 'descriptions', 'first_description', 'summaries', 'first_summary', '_package_implementations',
 932                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata', 'local_path']
 933
 934         def __init__(self, feed_element, local_path = None, distro = None):
 935                 """Create a feed object from a DOM.
 936                 @param feed_element: the root element of a feed file
 937                 @type feed_element: L{qdom.Element}
 938                 @param local_path: the pathname of this local feed, or None for remote feeds"""
 939                 self.local_path = local_path
 940                 self.implementations = {}
 941                 self.name = None
 942                 self.summaries = {}     # { lang: str }
 943                 self.first_summary = None
 944                 self.descriptions = {}  # { lang: str }
 945                 self.first_description = None
 946                 self.last_modified = None
 947                 self.feeds = []
 948                 self.feed_for = set()
 949                 self.metadata = []
 950                 self.last_checked = None
 951                 self._package_implementations = []
 952
 953                 if distro is not None:
 954                         import warnings
 955                         warnings.warn("distro argument is now ignored", DeprecationWarning, 2)
 956
 957                 if feed_element is None:
 958                         return                  # XXX subclass?
 959
 960                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 961                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 962
 963                 main = feed_element.getAttribute('main')
 964                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 965
 966                 if local_path:
 967                         self.url = local_path
 968                         local_dir = os.path.dirname(local_path)
 969                 else:
 970                         assert local_path is None
 971                         self.url = feed_element.getAttribute('uri')
 972                         if not self.url:
 973                                 raise InvalidInterface(_("<interface> uri attribute missing"))
 974                         local_dir = None        # Can't have relative paths
 975
 976                 min_injector_version = feed_element.getAttribute('min-injector-version')
 977                 if min_injector_version:
 978                         if parse_version(min_injector_version) > parse_version(version):
 979                                 raise InvalidInterface(_("This feed requires version %(min_version)s or later of "
 980                                                         "Zero Install, but I am only version %(version)s. "
 981                                                         "You can get a newer version from http://0install.net") %
 982                                                         {'min_version': min_injector_version, 'version': version})
 983
 984                 for x in feed_element.childNodes:
 985                         if x.uri != XMLNS_IFACE:
 986                                 self.metadata.append(x)
 987                                 continue
 988                         if x.name == 'name':
 989                                 self.name = x.content
 990                         elif x.name == 'description':
 991                                 if self.first_description == None:
 992                                         self.first_description = x.content
 993                                 self.descriptions[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 994                         elif x.name == 'summary':
 995                                 if self.first_summary == None:
 996                                         self.first_summary = x.content
 997                                 self.summaries[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 998                         elif x.name == 'feed-for':
 999                                 feed_iface = x.getAttribute('interface')
1000                                 if not feed_iface:
1001                                         raise InvalidInterface(_('Missing "interface" attribute in <feed-for>'))
1002                                 self.feed_for.add(feed_iface)
1003                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
1004                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
1005                                 # in case it happens again.
1006                                 logger.debug(_("Is feed-for %s"), feed_iface)
1007                         elif x.name == 'feed':
1008                                 feed_src = x.getAttribute('src')
1009                                 if not feed_src:
1010                                         raise InvalidInterface(_('Missing "src" attribute in <feed>'))
1011                                 if feed_src.startswith('http:') or feed_src.startswith('https:') or local_path:
1012                                         if feed_src.startswith('.'):
1013                                                 feed_src = os.path.abspath(os.path.join(local_dir, feed_src))
1014
1015                                         langs = x.getAttribute('langs')
1016                                         if langs: langs = langs.replace('_', '-')
1017                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = langs))
1018                                 else:
1019                                         raise InvalidInterface(_("Invalid feed URL '%s'") % feed_src)
1020                         else:
1021                                 self.metadata.append(x)
1022
1023                 if not self.name:
1024                         raise InvalidInterface(_("Missing <name> in feed"))
1025                 if not self.summary:
1026                         raise InvalidInterface(_("Missing <summary> in feed"))
1027
1028                 def process_group(group, group_attrs, base_depends, base_bindings, base_commands):
1029                         for item in group.childNodes:
1030                                 if item.uri != XMLNS_IFACE: continue
1031
1032                                 if item.name not in ('group', 'implementation', 'package-implementation'):
1033                                         continue
1034
1035                                 # We've found a group or implementation. Scan for dependencies,
1036                                 # bindings and commands. Doing this here means that:
1037                                 # - We can share the code for groups and implementations here.
1038                                 # - The order doesn't matter, because these get processed first.
1039                                 # A side-effect is that the document root cannot contain
1040                                 # these.
1041
1042                                 depends = base_depends[:]
1043                                 bindings = base_bindings[:]
1044                                 commands = base_commands.copy()
1045
1046                                 for attr, command in [('main', 'run'),
1047                                                       ('self-test', 'test')]:
1048                                         value = item.attrs.get(attr, None)
1049                                         if value is not None:
1050                                                 commands[command] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': command, 'path': value}), None)
1051
1052                                 for child in item.childNodes:
1053                                         if child.uri != XMLNS_IFACE: continue
1054                                         if child.name in _dependency_names:
1055                                                 dep = process_depends(child, local_dir)
1056                                                 depends.append(dep)
1057                                         elif child.name == 'command':
1058                                                 command_name = child.attrs.get('name', None)
1059                                                 if not command_name:
1060                                                         raise InvalidInterface('Missing name for <command>')
1061                                                 commands[command_name] = Command(child, local_dir)
1062                                         elif child.name in binding_names:
1063                                                 bindings.append(process_binding(child))
1064
1065                                 compile_command = item.attrs.get('http://zero-install.sourceforge.net/2006/namespaces/0compile command')
1066                                 if compile_command is not None:
1067                                         commands['compile'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': 'compile', 'shell-command': compile_command}), None)
1068
1069                                 item_attrs = _merge_attrs(group_attrs, item)
1070
1071                                 if item.name == 'group':
1072                                         process_group(item, item_attrs, depends, bindings, commands)
1073                                 elif item.name == 'implementation':
1074                                         process_impl(item, item_attrs, depends, bindings, commands)
1075                                 elif item.name == 'package-implementation':
1076                                         if depends:
1077                                                 logger.warn("A <package-implementation> with dependencies in %s!", self.url)
1078                                         self._package_implementations.append((item, item_attrs))
1079                                 else:
1080                                         assert 0
1081
1082                 def process_impl(item, item_attrs, depends, bindings, commands):
1083                         id = item.getAttribute('id')
1084                         if id is None:
1085                                 raise InvalidInterface(_("Missing 'id' attribute on %s") % item)
1086                         local_path = item_attrs.get('local-path')
1087                         if local_dir and local_path:
1088                                 abs_local_path = os.path.abspath(os.path.join(local_dir, local_path))
1089                                 impl = ZeroInstallImplementation(self, id, abs_local_path)
1090                         elif local_dir and (id.startswith('/') or id.startswith('.')):
1091                                 # For old feeds
1092                                 id = os.path.abspath(os.path.join(local_dir, id))
1093                                 impl = ZeroInstallImplementation(self, id, id)
1094                         else:
1095                                 impl = ZeroInstallImplementation(self, id, None)
1096                                 if '=' in id:
1097                                         # In older feeds, the ID was the (single) digest
1098                                         impl.digests.append(id)
1099                         if id in self.implementations:
1100                                 logger.warn(_("Duplicate ID '%(id)s' in feed '%(feed)s'"), {'id': id, 'feed': self})
1101                         self.implementations[id] = impl
1102
1103                         impl.metadata = item_attrs
1104                         try:
1105                                 version_mod = item_attrs.get('version-modifier', None)
1106                                 if version_mod:
1107                                         item_attrs['version'] += version_mod
1108                                         del item_attrs['version-modifier']
1109                                 version = item_attrs['version']
1110                         except KeyError:
1111                                 raise InvalidInterface(_("Missing version attribute"))
1112                         impl.version = parse_version(version)
1113
1114                         impl.commands = commands
1115
1116                         impl.released = item_attrs.get('released', None)
1117                         impl.langs = item_attrs.get('langs', '').replace('_', '-')
1118
1119                         size = item.getAttribute('size')
1120                         if size:
1121                                 impl.size = int(size)
1122                         impl.arch = item_attrs.get('arch', None)
1123                         try:
1124                                 stability = stability_levels[str(item_attrs['stability'])]
1125                         except KeyError:
1126                                 stab = str(item_attrs['stability'])
1127                                 if stab != stab.lower():
1128                                         raise InvalidInterface(_('Stability "%s" invalid - use lower case!') % item_attrs.stability)
1129                                 raise InvalidInterface(_('Stability "%s" invalid') % item_attrs['stability'])
1130                         if stability >= preferred:
1131                                 raise InvalidInterface(_("Upstream can't set stability to preferred!"))
1132                         impl.upstream_stability = stability
1133
1134                         impl.bindings = bindings
1135                         impl.requires = depends
1136
1137                         for elem in item.childNodes:
1138                                 if elem.uri != XMLNS_IFACE: continue
1139                                 if elem.name == 'archive':
1140                                         url = elem.getAttribute('href')
1141                                         if not url:
1142                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1143                                         size = elem.getAttribute('size')
1144                                         if not size:
1145                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1146                                         impl.add_download_source(url = url, size = int(size),
1147                                                         extract = elem.getAttribute('extract'),
1148                                                         start_offset = _get_long(elem, 'start-offset'),
1149                                                         type = elem.getAttribute('type'))
1150                                 elif elem.name == 'manifest-digest':
1151                                         for aname, avalue in elem.attrs.items():
1152                                                 if ' ' not in aname:
1153                                                         impl.digests.append(zerostore.format_algorithm_digest_pair(aname, avalue))
1154                                 elif elem.name == 'recipe':
1155                                         recipe = Recipe()
1156                                         for recipe_step in elem.childNodes:
1157                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
1158                                                         url = recipe_step.getAttribute('href')
1159                                                         if not url:
1160                                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1161                                                         size = recipe_step.getAttribute('size')
1162                                                         if not size:
1163                                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1164                                                         recipe.steps.append(DownloadSource(None, url = url, size = int(size),
1165                                                                         extract = recipe_step.getAttribute('extract'),
1166                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
1167                                                                         type = recipe_step.getAttribute('type')))
1168                                                 elif recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'rename':
1169                                                         source = recipe_step.getAttribute('source')
1170                                                         if not source:
1171                                                                 raise InvalidInterface(_("Missing source attribute on <rename>"))
1172                                                         dest = recipe_step.getAttribute('dest')
1173                                                         if not dest:
1174                                                                 raise InvalidInterface(_("Missing dest attribute on <rename>"))
1175                                                         recipe.steps.append(RenameStep(source=source, dest=dest))
1176                                                 else:
1177                                                         logger.info(_("Unknown step '%s' in recipe; skipping recipe"), recipe_step.name)
1178                                                         break
1179                                         else:
1180                                                 impl.download_sources.append(recipe)
1181
1182                 root_attrs = {'stability': 'testing'}
1183                 root_commands = {}
1184                 if main:
1185                         logger.info("Note: @main on document element is deprecated in %s", self)
1186                         root_commands['run'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': main, 'name': 'run'}), None)
1187                 process_group(feed_element, root_attrs, [], [], root_commands)
1188
1189         def get_distro_feed(self):
1190                 """Does this feed contain any <pacakge-implementation> elements?
1191                 i.e. is it worth asking the package manager for more information?
1192                 @return: the URL of the virtual feed, or None
1193                 @since: 0.49"""
1194                 if self._package_implementations:
1195                         return "distribution:" + self.url
1196                 return None
1197
1198         def get_package_impls(self, distro):
1199                 """Find the best <pacakge-implementation> element(s) for the given distribution.
1200                 @param distro: the distribution to use to rate them
1201                 @type distro: L{distro.Distribution}
1202                 @return: a list of tuples for the best ranked elements
1203                 @rtype: [str]
1204                 @since: 0.49"""
1205                 best_score = 0
1206                 best_impls = []
1207
1208                 for item, item_attrs in self._package_implementations:
1209                         distro_names = item_attrs.get('distributions', '')
1210                         score_this_item = max(
1211                                 distro.get_score(distro_name) if distro_name else 0.5
1212                                 for distro_name in distro_names.split(' '))
1213                         if score_this_item > best_score:
1214                                 best_score = score_this_item
1215                                 best_impls = []
1216                         if score_this_item == best_score:
1217                                 best_impls.append((item, item_attrs))
1218                 return best_impls
1219
1220         def get_name(self):
1221                 return self.name or '(' + os.path.basename(self.url) + ')'
1222
1223         def __repr__(self):
1224                 return _("<Feed %s>") % self.url
1225
1226         def set_stability_policy(self, new):
1227                 assert new is None or isinstance(new, Stability)
1228                 self.stability_policy = new
1229
1230         def get_feed(self, url):
1231                 for x in self.feeds:
1232                         if x.uri == url:
1233                                 return x
1234                 return None
1235
1236         def add_metadata(self, elem):
1237                 self.metadata.append(elem)
1238
1239         def get_metadata(self, uri, name):
1240                 """Return a list of interface metadata elements with this name and namespace URI."""
1241                 return [m for m in self.metadata if m.name == name and m.uri == uri]
1242
1243         @property
1244         def summary(self):
1245                 return _best_language_match(self.summaries) or self.first_summary
1246
1247         @property
1248         def description(self):
1249                 return _best_language_match(self.descriptions) or self.first_description
1250
1251         def get_replaced_by(self):
1252                 """Return the URI of the interface that replaced the one with the URI of this feed's URL.
1253                 This is the value of the feed's <replaced-by interface'...'/> element.
1254                 @return: the new URI, or None if it hasn't been replaced
1255                 @since: 1.7"""
1256                 for child in self.metadata:
1257                         if child.uri == XMLNS_IFACE and child.name == 'replaced-by':
1258                                 new_uri = child.getAttribute('interface')
1259                                 if new_uri and (new_uri.startswith('http:') or new_uri.startswith('https:') or self.local_path):
1260                                         return new_uri
1261                 return None
1262
1263 class DummyFeed(object):
1264         """Temporary class used during API transition."""
1265         last_modified = None
1266         name = '-'
1267         last_checked = property(lambda self: None)
1268         implementations = property(lambda self: {})
1269         feeds = property(lambda self: [])
1270         summary = property(lambda self: '-')
1271         description = property(lambda self: '')
1272         def get_name(self): return self.name
1273         def get_feed(self, url): return None
1274         def get_metadata(self, uri, name): return []
1275 _dummy_feed = DummyFeed()
1276
1277 if sys.version_info[0] > 2:
1278         # Python 3
1279
1280         from functools import total_ordering
1281         # (note: delete these two lines when generating epydoc)
1282         Stability = total_ordering(Stability)
1283         Implementation = total_ordering(Implementation)
1284
1285         # These could be replaced by urllib.parse.quote, except that
1286         # it uses upper-case escapes and we use lower-case ones...
1287         def unescape(uri):
1288                 """Convert each %20 to a space, etc.
1289                 @rtype: str"""
1290                 uri = uri.replace('#', '/')
1291                 if '%' not in uri: return uri
1292                 return re.sub(b'%[0-9a-fA-F][0-9a-fA-F]',
1293                         lambda match: bytes([int(match.group(0)[1:], 16)]),
1294                         uri.encode('ascii')).decode('utf-8')
1295
1296         def escape(uri):
1297                 """Convert each space to %20, etc
1298                 @rtype: str"""
1299                 return re.sub(b'[^-_.a-zA-Z0-9]',
1300                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1301                         uri.encode('utf-8')).decode('ascii')
1302
1303         def _pretty_escape(uri):
1304                 """Convert each space to %20, etc
1305                 : is preserved and / becomes #. This makes for nicer strings,
1306                 and may replace L{escape} everywhere in future.
1307                 @rtype: str"""
1308                 if os.name == "posix":
1309                         # Only preserve : on Posix systems
1310                         preserveRegex = b'[^-_.a-zA-Z0-9:/]'
1311                 else:
1312                         # Other OSes may not allow the : character in file names
1313                         preserveRegex = b'[^-_.a-zA-Z0-9/]'
1314                 return re.sub(preserveRegex,
1315                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1316                         uri.encode('utf-8')).decode('ascii').replace('/', '#')
1317 else:
1318         # Python 2
1319
1320         def unescape(uri):
1321                 """Convert each %20 to a space, etc.
1322                 @rtype: str"""
1323                 uri = uri.replace('#', '/')
1324                 if '%' not in uri: return uri
1325                 return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
1326                         lambda match: chr(int(match.group(0)[1:], 16)),
1327                         uri).decode('utf-8')
1328
1329         def escape(uri):
1330                 """Convert each space to %20, etc
1331                 @rtype: str"""
1332                 return re.sub('[^-_.a-zA-Z0-9]',
1333                         lambda match: '%%%02x' % ord(match.group(0)),
1334                         uri.encode('utf-8'))
1335
1336         def _pretty_escape(uri):
1337                 """Convert each space to %20, etc
1338                 : is preserved and / becomes #. This makes for nicer strings,
1339                 and may replace L{escape} everywhere in future.
1340                 @rtype: str"""
1341                 if os.name == "posix":
1342                         # Only preserve : on Posix systems
1343                         preserveRegex = '[^-_.a-zA-Z0-9:/]'
1344                 else:
1345                         # Other OSes may not allow the : character in file names
1346                         preserveRegex = '[^-_.a-zA-Z0-9/]'
1347                 return re.sub(preserveRegex,
1348                         lambda match: '%%%02x' % ord(match.group(0)),
1349                         uri.encode('utf-8')).replace('/', '#')
1350
1351 def canonical_iface_uri(uri):
1352         """If uri is a relative path, convert to an absolute one.
1353         A "file:///foo" URI is converted to "/foo".
1354         An "alias:prog" URI expands to the URI in the 0alias script
1355         Otherwise, return it unmodified.
1356         @rtype: str
1357         @raise SafeException: if uri isn't valid
1358         """
1359         if uri.startswith('http://') or uri.startswith('https://'):
1360                 if uri.count("/") < 3:
1361                         raise SafeException(_("Missing / after hostname in URI '%s'") % uri)
1362                 return uri
1363         elif uri.startswith('file:///'):
1364                 path = uri[7:]
1365         elif uri.startswith('file:'):
1366                 if uri[5] == '/':
1367                         raise SafeException(_('Use file:///path for absolute paths, not {uri}').format(uri = uri))
1368                 path = os.path.abspath(uri[5:])
1369         elif uri.startswith('alias:'):
1370                 from zeroinstall import alias
1371                 alias_prog = uri[6:]
1372                 if not os.path.isabs(alias_prog):
1373                         full_path = support.find_in_path(alias_prog)
1374                         if not full_path:
1375                                 raise alias.NotAnAliasScript("Not found in $PATH: " + alias_prog)
1376                 else:
1377                         full_path = alias_prog
1378                 return alias.parse_script(full_path).uri
1379         else:
1380                 path = os.path.realpath(uri)
1381
1382         if os.path.isfile(path):
1383                 return path
1384         raise SafeException(_("Bad interface name '%(uri)s'.\n"
1385                         "(doesn't start with 'http:', and "
1386                         "doesn't exist as a local file '%(interface_uri)s' either)") %
1387                         {'uri': uri, 'interface_uri': path})
1388
1389 _version_mod_to_value = {
1390         'pre': -2,
1391         'rc': -1,
1392         '': 0,
1393         'post': 1,
1394 }
1395
1396 # Reverse mapping
1397 _version_value_to_mod = {}
1398 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
1399 del x
1400
1401 _version_re = re.compile('-([a-z]*)')
1402
1403 def parse_version(version_string):
1404         """Convert a version string to an internal representation.
1405         The parsed format can be compared quickly using the standard Python functions.
1406          - Version := DottedList ("-" Mod DottedList?)*
1407          - DottedList := (Integer ("." Integer)*)
1408         @rtype: tuple (opaque)
1409         @raise SafeException: if the string isn't a valid version
1410         @since: 0.24 (moved from L{reader}, from where it is still available):"""
1411         if version_string is None: return None
1412         parts = _version_re.split(version_string)
1413         if parts[-1] == '':
1414                 del parts[-1]   # Ends with a modifier
1415         else:
1416                 parts.append('')
1417         if not parts:
1418                 raise SafeException(_("Empty version string!"))
1419         l = len(parts)
1420         try:
1421                 for x in range(0, l, 2):
1422                         part = parts[x]
1423                         if part:
1424                                 parts[x] = list(map(int, parts[x].split('.')))
1425                         else:
1426                                 parts[x] = []   # (because ''.split('.') == [''], not [])
1427                 for x in range(1, l, 2):
1428                         parts[x] = _version_mod_to_value[parts[x]]
1429                 return parts
1430         except ValueError as ex:
1431                 raise SafeException(_("Invalid version format in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1432         except KeyError as ex:
1433                 raise SafeException(_("Invalid version modifier in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1434
1435 def format_version(version):
1436         """Format a parsed version for display. Undoes the effect of L{parse_version}.
1437         @see: L{Implementation.get_version}
1438         @rtype: str
1439         @since: 0.24"""
1440         version = version[:]
1441         l = len(version)
1442         for x in range(0, l, 2):
1443                 version[x] = '.'.join(map(str, version[x]))
1444         for x in range(1, l, 2):
1445                 version[x] = '-' + _version_value_to_mod[version[x]]
1446         if version[-1] == '-': del version[-1]
1447         return ''.join(version)
1448