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