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