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, sys
  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 import support, zerostore
  23
  24 # Element names for bindings in feed files
  25 binding_names = frozenset(['environment', 'overlay', 'executable-in-path', 'executable-in-var'])
  26
  27 _dependency_names = frozenset(['requires', 'restricts'])
  28
  29 network_offline = 'off-line'
  30 network_minimal = 'minimal'
  31 network_full = 'full'
  32 network_levels = (network_offline, network_minimal, network_full)
  33
  34 stability_levels = {}   # Name -> Stability
  35
  36 defaults = {
  37         'PATH': '/bin:/usr/bin',
  38         'XDG_CONFIG_DIRS': '/etc/xdg',
  39         'XDG_DATA_DIRS': '/usr/local/share:/usr/share',
  40 }
  41
  42 class InvalidInterface(SafeException):
  43         """Raised when parsing an invalid feed."""
  44         feed_url = None
  45
  46         def __init__(self, message, ex = None):
  47                 if ex:
  48                         try:
  49                                 message += "\n\n(exact error: %s)" % ex
  50                         except:
  51                                 # Some Python messages have type str but contain UTF-8 sequences.
  52                                 # (e.g. IOException). Adding these to a Unicode 'message' (e.g.
  53                                 # after gettext translation) will cause an error.
  54                                 import codecs
  55                                 decoder = codecs.lookup('utf-8')
  56                                 decex = decoder.decode(str(ex), errors = 'replace')[0]
  57                                 message += "\n\n(exact error: %s)" % decex
  58
  59                 SafeException.__init__(self, message)
  60
  61         def __unicode__(self):
  62                 if hasattr(SafeException, '__unicode__'):
  63                         # Python >= 2.6
  64                         if self.feed_url:
  65                                 return _('%s [%s]') % (SafeException.__unicode__(self), self.feed_url)
  66                         return SafeException.__unicode__(self)
  67                 else:
  68                         return support.unicode(SafeException.__str__(self))
  69
  70 def _split_arch(arch):
  71         """Split an arch into an (os, machine) tuple. Either or both parts may be None."""
  72         if not arch:
  73                 return None, None
  74         elif '-' not in arch:
  75                 raise SafeException(_("Malformed arch '%s'") % arch)
  76         else:
  77                 osys, machine = arch.split('-', 1)
  78                 if osys == '*': osys = None
  79                 if machine == '*': machine = None
  80                 return osys, machine
  81
  82 def _join_arch(osys, machine):
  83         if osys == machine == None: return None
  84         return "%s-%s" % (osys or '*', machine or '*')
  85
  86 def _best_language_match(options):
  87         (language, encoding) = locale.getlocale()
  88
  89         if language:
  90                 # xml:lang uses '-', while LANG uses '_'
  91                 language = language.replace('_', '-')
  92         else:
  93                 language = 'en-US'
  94
  95         return (options.get(language, None) or                  # Exact match (language+region)
  96                 options.get(language.split('-', 1)[0], None) or # Matching language
  97                 options.get('en', None))                        # English
  98
  99 class Stability(object):
 100         """A stability rating. Each implementation has an upstream stability rating and,
 101         optionally, a user-set rating."""
 102         __slots__ = ['level', 'name', 'description']
 103         def __init__(self, level, name, description):
 104                 self.level = level
 105                 self.name = name
 106                 self.description = description
 107                 assert name not in stability_levels
 108                 stability_levels[name] = self
 109
 110         def __cmp__(self, other):
 111                 return cmp(self.level, other.level)
 112
 113         def __lt__(self, other):
 114                 if isinstance(other, Stability):
 115                         return self.level < other.level
 116                 else:
 117                         return NotImplemented
 118
 119         def __eq__(self, other):
 120                 if isinstance(other, Stability):
 121                         return self.level == other.level
 122                 else:
 123                         return NotImplemented
 124
 125         def __str__(self):
 126                 return self.name
 127
 128         def __repr__(self):
 129                 return _("<Stability: %s>") % self.description
 130
 131 def process_binding(e):
 132         """Internal"""
 133         if e.name == 'environment':
 134                 mode = {
 135                         None: EnvironmentBinding.PREPEND,
 136                         'prepend': EnvironmentBinding.PREPEND,
 137                         'append': EnvironmentBinding.APPEND,
 138                         'replace': EnvironmentBinding.REPLACE,
 139                 }[e.getAttribute('mode')]
 140
 141                 binding = EnvironmentBinding(e.getAttribute('name'),
 142                                              insert = e.getAttribute('insert'),
 143                                              default = e.getAttribute('default'),
 144                                              value = e.getAttribute('value'),
 145                                              mode = mode,
 146                                              separator = e.getAttribute('separator'))
 147                 if not binding.name: raise InvalidInterface(_("Missing 'name' in binding"))
 148                 if binding.insert is None and binding.value is None:
 149                         raise InvalidInterface(_("Missing 'insert' or 'value' in binding"))
 150                 if binding.insert is not None and binding.value is not None:
 151                         raise InvalidInterface(_("Binding contains both 'insert' and 'value'"))
 152                 return binding
 153         elif e.name == 'executable-in-path':
 154                 return ExecutableBinding(e, in_path = True)
 155         elif e.name == 'executable-in-var':
 156                 return ExecutableBinding(e, in_path = False)
 157         elif e.name == 'overlay':
 158                 return OverlayBinding(e.getAttribute('src'), e.getAttribute('mount-point'))
 159         else:
 160                 raise Exception(_("Unknown binding type '%s'") % e.name)
 161
 162 def process_depends(item, local_feed_dir):
 163         """Internal"""
 164         # Note: also called from selections
 165         attrs = item.attrs
 166         dep_iface = item.getAttribute('interface')
 167         if not dep_iface:
 168                 raise InvalidInterface(_("Missing 'interface' on <%s>") % item.name)
 169         if dep_iface.startswith('.'):
 170                 if local_feed_dir:
 171                         dep_iface = os.path.abspath(os.path.join(local_feed_dir, dep_iface))
 172                         # (updates the element too, in case we write it out again)
 173                         attrs['interface'] = dep_iface
 174                 else:
 175                         raise InvalidInterface(_('Relative interface URI "%s" in non-local feed') % dep_iface)
 176
 177         if item.name == 'restricts':
 178                 dependency = InterfaceRestriction(dep_iface, element = item)
 179         else:
 180                 dependency = InterfaceDependency(dep_iface, element = item)
 181
 182         for e in item.childNodes:
 183                 if e.uri != XMLNS_IFACE: continue
 184                 if e.name in binding_names:
 185                         dependency.bindings.append(process_binding(e))
 186                 elif e.name == 'version':
 187                         dependency.restrictions.append(
 188                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 189                                                         before = parse_version(e.getAttribute('before'))))
 190         return dependency
 191
 192 def N_(message): return message
 193
 194 insecure = Stability(0, N_('insecure'), _('This is a security risk'))
 195 buggy = Stability(5, N_('buggy'), _('Known to have serious bugs'))
 196 developer = Stability(10, N_('developer'), _('Work-in-progress - bugs likely'))
 197 testing = Stability(20, N_('testing'), _('Stability unknown - please test!'))
 198 stable = Stability(30, N_('stable'), _('Tested - no serious problems found'))
 199 packaged = Stability(35, N_('packaged'), _('Supplied by the local package manager'))
 200 preferred = Stability(40, N_('preferred'), _('Best of all - must be set manually'))
 201
 202 del N_
 203
 204 class Restriction(object):
 205         """A Restriction limits the allowed implementations of an Interface."""
 206         __slots__ = []
 207
 208         def meets_restriction(self, impl):
 209                 """Called by the L{solver.Solver} to check whether a particular implementation is acceptable.
 210                 @return: False if this implementation is not a possibility
 211                 @rtype: bool
 212                 """
 213                 raise NotImplementedError(_("Abstract"))
 214
 215 class VersionRestriction(Restriction):
 216         """Only select implementations with a particular version number.
 217         @since: 0.40"""
 218
 219         def __init__(self, version):
 220                 """@param version: the required version number
 221                 @see: L{parse_version}; use this to pre-process the version number
 222                 """
 223                 self.version = version
 224
 225         def meets_restriction(self, impl):
 226                 return impl.version == self.version
 227
 228         def __str__(self):
 229                 return _("(restriction: version = %s)") % format_version(self.version)
 230
 231 class VersionRangeRestriction(Restriction):
 232         """Only versions within the given range are acceptable"""
 233         __slots__ = ['before', 'not_before']
 234
 235         def __init__(self, before, not_before):
 236                 """@param before: chosen versions must be earlier than this
 237                 @param not_before: versions must be at least this high
 238                 @see: L{parse_version}; use this to pre-process the versions
 239                 """
 240                 self.before = before
 241                 self.not_before = not_before
 242
 243         def meets_restriction(self, impl):
 244                 if self.not_before and impl.version < self.not_before:
 245                         return False
 246                 if self.before and impl.version >= self.before:
 247                         return False
 248                 return True
 249
 250         def __str__(self):
 251                 if self.not_before is not None or self.before is not None:
 252                         range = ''
 253                         if self.not_before is not None:
 254                                 range += format_version(self.not_before) + ' <= '
 255                         range += 'version'
 256                         if self.before is not None:
 257                                 range += ' < ' + format_version(self.before)
 258                 else:
 259                         range = 'none'
 260                 return _("(restriction: %s)") % range
 261
 262 class Binding(object):
 263         """Information about how the choice of a Dependency is made known
 264         to the application being run."""
 265
 266         @property
 267         def command(self):
 268                 """"Returns the name of the specific command needed by this binding, if any.
 269                 @since: 1.2"""
 270                 return None
 271
 272 class EnvironmentBinding(Binding):
 273         """Indicate the chosen implementation using an environment variable."""
 274         __slots__ = ['name', 'insert', 'default', 'mode', 'value']
 275
 276         PREPEND = 'prepend'
 277         APPEND = 'append'
 278         REPLACE = 'replace'
 279
 280         def __init__(self, name, insert, default = None, mode = PREPEND, value=None, separator=None):
 281                 """
 282                 mode argument added in version 0.28
 283                 value argument added in version 0.52
 284                 """
 285                 self.name = name
 286                 self.insert = insert
 287                 self.default = default
 288                 self.mode = mode
 289                 self.value = value
 290                 if separator is None:
 291                         self.separator = os.pathsep
 292                 else:
 293                         self.separator = separator
 294
 295
 296         def __str__(self):
 297                 return _("<environ %(name)s %(mode)s %(insert)s %(value)s>") % \
 298                         {'name': self.name, 'mode': self.mode, 'insert': self.insert, 'value': self.value}
 299
 300         __repr__ = __str__
 301
 302         def get_value(self, path, old_value):
 303                 """Calculate the new value of the environment variable after applying this binding.
 304                 @param path: the path to the selected implementation
 305                 @param old_value: the current value of the environment variable
 306                 @return: the new value for the environment variable"""
 307
 308                 if self.insert is not None:
 309                         extra = os.path.join(path, self.insert)
 310                 else:
 311                         assert self.value is not None
 312                         extra = self.value
 313
 314                 if self.mode == EnvironmentBinding.REPLACE:
 315                         return extra
 316
 317                 if old_value is None:
 318                         old_value = self.default or defaults.get(self.name, None)
 319                 if old_value is None:
 320                         return extra
 321                 if self.mode == EnvironmentBinding.PREPEND:
 322                         return extra + self.separator + old_value
 323                 else:
 324                         return old_value + self.separator + extra
 325
 326         def _toxml(self, doc, prefixes):
 327                 """Create a DOM element for this binding.
 328                 @param doc: document to use to create the element
 329                 @return: the new element
 330                 """
 331                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 332                 env_elem.setAttributeNS(None, 'name', self.name)
 333                 if self.mode is not None:
 334                         env_elem.setAttributeNS(None, 'mode', self.mode)
 335                 if self.insert is not None:
 336                         env_elem.setAttributeNS(None, 'insert', self.insert)
 337                 else:
 338                         env_elem.setAttributeNS(None, 'value', self.value)
 339                 if self.default:
 340                         env_elem.setAttributeNS(None, 'default', self.default)
 341                 if self.separator:
 342                         env_elem.setAttributeNS(None, 'separator', self.separator)
 343                 return env_elem
 344
 345 class ExecutableBinding(Binding):
 346         """Make the chosen command available in $PATH.
 347         @ivar in_path: True to add the named command to $PATH, False to store in named variable
 348         @type in_path: bool
 349         """
 350         __slots__ = ['qdom']
 351
 352         def __init__(self, qdom, in_path):
 353                 self.qdom = qdom
 354                 self.in_path = in_path
 355
 356         def __str__(self):
 357                 return str(self.qdom)
 358
 359         __repr__ = __str__
 360
 361         def _toxml(self, doc, prefixes):
 362                 return self.qdom.toDOM(doc, prefixes)
 363
 364         @property
 365         def name(self):
 366                 return self.qdom.getAttribute('name')
 367
 368         @property
 369         def command(self):
 370                 return self.qdom.getAttribute("command") or 'run'
 371
 372 class OverlayBinding(Binding):
 373         """Make the chosen implementation available by overlaying it onto another part of the file-system.
 374         This is to support legacy programs which use hard-coded paths."""
 375         __slots__ = ['src', 'mount_point']
 376
 377         def __init__(self, src, mount_point):
 378                 self.src = src
 379                 self.mount_point = mount_point
 380
 381         def __str__(self):
 382                 return _("<overlay %(src)s on %(mount_point)s>") % {'src': self.src or '.', 'mount_point': self.mount_point or '/'}
 383
 384         __repr__ = __str__
 385
 386         def _toxml(self, doc, prefixes):
 387                 """Create a DOM element for this binding.
 388                 @param doc: document to use to create the element
 389                 @return: the new element
 390                 """
 391                 env_elem = doc.createElementNS(XMLNS_IFACE, 'overlay')
 392                 if self.src is not None:
 393                         env_elem.setAttributeNS(None, 'src', self.src)
 394                 if self.mount_point is not None:
 395                         env_elem.setAttributeNS(None, 'mount-point', self.mount_point)
 396                 return env_elem
 397
 398 class Feed(object):
 399         """An interface's feeds are other interfaces whose implementations can also be
 400         used as implementations of this interface."""
 401         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs', 'site_package']
 402         def __init__(self, uri, arch, user_override, langs = None, site_package = False):
 403                 self.uri = uri
 404                 # This indicates whether the feed comes from the user's overrides
 405                 # file. If true, writer.py will write it when saving.
 406                 self.user_override = user_override
 407                 self.os, self.machine = _split_arch(arch)
 408                 self.langs = langs
 409                 self.site_package = site_package
 410
 411         def __str__(self):
 412                 return "<Feed from %s>" % self.uri
 413         __repr__ = __str__
 414
 415         arch = property(lambda self: _join_arch(self.os, self.machine))
 416
 417 class Dependency(object):
 418         """A Dependency indicates that an Implementation requires some additional
 419         code to function. This is an abstract base class.
 420         @ivar qdom: the XML element for this Dependency (since 0launch 0.51)
 421         @type qdom: L{qdom.Element}
 422         @ivar metadata: any extra attributes from the XML element
 423         @type metadata: {str: str}
 424         """
 425         __slots__ = ['qdom']
 426
 427         Essential = "essential"         # Must select a version of the dependency
 428         Recommended = "recommended"     # Prefer to select a version
 429         Restricts = "restricts"         # Just adds restrictions without expressing any opinion
 430
 431         def __init__(self, element):
 432                 assert isinstance(element, qdom.Element), type(element) # Use InterfaceDependency instead!
 433                 self.qdom = element
 434
 435         @property
 436         def metadata(self):
 437                 return self.qdom.attrs
 438
 439         def get_required_commands(self):
 440                 """Return a list of command names needed by this dependency"""
 441                 return []
 442
 443 class InterfaceRestriction(Dependency):
 444         """A Dependency that restricts the possible choices of a Zero Install interface.
 445         @ivar interface: the interface required by this dependency
 446         @type interface: str
 447         @ivar restrictions: a list of constraints on acceptable implementations
 448         @type restrictions: [L{Restriction}]
 449         @since: 1.10
 450         """
 451         __slots__ = ['interface', 'restrictions']
 452
 453         def __init__(self, interface, restrictions = None, element = None):
 454                 Dependency.__init__(self, element)
 455                 assert isinstance(interface, (str, support.unicode))
 456                 assert interface
 457                 self.interface = interface
 458                 if restrictions is None:
 459                         self.restrictions = []
 460                 else:
 461                         self.restrictions = restrictions
 462
 463         importance = Dependency.Restricts
 464         bindings = ()
 465
 466         def __str__(self):
 467                 return _("<Restriction on %(interface)s; %(restrictions)s>") % {'interface': self.interface, 'restrictions': self.restrictions}
 468
 469 class InterfaceDependency(InterfaceRestriction):
 470         """A Dependency on a Zero Install interface.
 471         @ivar interface: the interface required by this dependency
 472         @type interface: str
 473         @ivar restrictions: a list of constraints on acceptable implementations
 474         @type restrictions: [L{Restriction}]
 475         @ivar bindings: how to make the choice of implementation known
 476         @type bindings: [L{Binding}]
 477         @since: 0.28
 478         """
 479         __slots__ = ['bindings']
 480
 481         def __init__(self, interface, restrictions = None, element = None):
 482                 InterfaceRestriction.__init__(self, interface, restrictions, element)
 483                 self.bindings = []
 484
 485         def __str__(self):
 486                 return _("<Dependency on %(interface)s; bindings: %(bindings)s%(restrictions)s>") % {'interface': self.interface, 'bindings': self.bindings, 'restrictions': self.restrictions}
 487
 488         @property
 489         def importance(self):
 490                 return self.qdom.getAttribute("importance") or Dependency.Essential
 491
 492         def get_required_commands(self):
 493                 """Return a list of command names needed by this dependency"""
 494                 if self.qdom.name == 'runner':
 495                         commands = [self.qdom.getAttribute('command') or 'run']
 496                 else:
 497                         commands = []
 498                 for b in self.bindings:
 499                         c = b.command
 500                         if c is not None:
 501                                 commands.append(c)
 502                 return commands
 503
 504         @property
 505         def command(self):
 506                 if self.qdom.name == 'runner':
 507                         return self.qdom.getAttribute('command') or 'run'
 508                 return None
 509
 510 class RetrievalMethod(object):
 511         """A RetrievalMethod provides a way to fetch an implementation."""
 512         __slots__ = []
 513
 514 class DownloadSource(RetrievalMethod):
 515         """A DownloadSource provides a way to fetch an implementation."""
 516         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 517
 518         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 519                 self.implementation = implementation
 520                 self.url = url
 521                 self.size = size
 522                 self.extract = extract
 523                 self.start_offset = start_offset
 524                 self.type = type                # MIME type - see unpack.py
 525
 526 class RenameStep(RetrievalMethod):
 527         """A Rename provides a way to rename / move a file within an implementation."""
 528         __slots__ = ['source', 'dest']
 529
 530         def __init__(self, source, dest):
 531                 self.source = source
 532                 self.dest = dest
 533
 534 class Recipe(RetrievalMethod):
 535         """Get an implementation by following a series of steps.
 536         @ivar size: the combined download sizes from all the steps
 537         @type size: int
 538         @ivar steps: the sequence of steps which must be performed
 539         @type steps: [L{RetrievalMethod}]"""
 540         __slots__ = ['steps']
 541
 542         def __init__(self):
 543                 self.steps = []
 544
 545         size = property(lambda self: sum([x.size for x in self.steps if isinstance(x, DownloadSource)]))
 546
 547 class DistributionSource(RetrievalMethod):
 548         """A package that is installed using the distribution's tools (including PackageKit).
 549         @ivar install: a function to call to install this package
 550         @type install: (L{handler.Handler}) -> L{tasks.Blocker}
 551         @ivar package_id: the package name, in a form recognised by the distribution's tools
 552         @type package_id: str
 553         @ivar size: the download size in bytes
 554         @type size: int
 555         @ivar needs_confirmation: whether the user should be asked to confirm before calling install()
 556         @type needs_confirmation: bool"""
 557
 558         __slots__ = ['package_id', 'size', 'install', 'needs_confirmation']
 559
 560         def __init__(self, package_id, size, install, needs_confirmation = True):
 561                 RetrievalMethod.__init__(self)
 562                 self.package_id = package_id
 563                 self.size = size
 564                 self.install = install
 565                 self.needs_confirmation = needs_confirmation
 566
 567 class Command(object):
 568         """A Command is a way of running an Implementation as a program."""
 569
 570         __slots__ = ['qdom', '_depends', '_local_dir', '_runner', '_bindings']
 571
 572         def __init__(self, qdom, local_dir):
 573                 """@param qdom: the <command> element
 574                 @param local_dir: the directory containing the feed (for relative dependencies), or None if not local
 575                 """
 576                 assert qdom.name == 'command', 'not <command>: %s' % qdom
 577                 self.qdom = qdom
 578                 self._local_dir = local_dir
 579                 self._depends = None
 580                 self._bindings = None
 581
 582         path = property(lambda self: self.qdom.attrs.get("path", None))
 583
 584         def _toxml(self, doc, prefixes):
 585                 return self.qdom.toDOM(doc, prefixes)
 586
 587         @property
 588         def requires(self):
 589                 if self._depends is None:
 590                         self._runner = None
 591                         depends = []
 592                         for child in self.qdom.childNodes:
 593                                 if child.name in _dependency_names:
 594                                         dep = process_depends(child, self._local_dir)
 595                                         depends.append(dep)
 596                                 elif child.name == 'runner':
 597                                         if self._runner:
 598                                                 raise InvalidInterface(_("Multiple <runner>s in <command>!"))
 599                                         dep = process_depends(child, self._local_dir)
 600                                         depends.append(dep)
 601                                         self._runner = dep
 602                         self._depends = depends
 603                 return self._depends
 604
 605         def get_runner(self):
 606                 self.requires           # (sets _runner)
 607                 return self._runner
 608
 609         def __str__(self):
 610                 return str(self.qdom)
 611
 612         @property
 613         def bindings(self):
 614                 """@since: 1.3"""
 615                 if self._bindings is None:
 616                         bindings = []
 617                         for e in self.qdom.childNodes:
 618                                 if e.uri != XMLNS_IFACE: continue
 619                                 if e.name in binding_names:
 620                                         bindings.append(process_binding(e))
 621                         self._bindings = bindings
 622                 return self._bindings
 623
 624 class Implementation(object):
 625         """An Implementation is a package which implements an Interface.
 626         @ivar download_sources: list of methods of getting this implementation
 627         @type download_sources: [L{RetrievalMethod}]
 628         @ivar feed: the feed owning this implementation (since 0.32)
 629         @type feed: [L{ZeroInstallFeed}]
 630         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 631         @type bindings: [Binding]
 632         @ivar upstream_stability: the stability reported by the packager
 633         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged]
 634         @ivar user_stability: the stability as set by the user
 635         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged | preferred]
 636         @ivar langs: natural languages supported by this package
 637         @type langs: str
 638         @ivar requires: interfaces this package depends on
 639         @type requires: [L{Dependency}]
 640         @ivar commands: ways to execute as a program
 641         @type commands: {str: Command}
 642         @ivar metadata: extra metadata from the feed
 643         @type metadata: {"[URI ]localName": str}
 644         @ivar id: a unique identifier for this Implementation
 645         @ivar version: a parsed version number
 646         @ivar released: release date
 647         @ivar local_path: the directory containing this local implementation, or None if it isn't local (id isn't a path)
 648         @type local_path: str | None
 649         @ivar requires_root_install: whether the user will need admin rights to use this
 650         @type requires_root_install: bool
 651         """
 652
 653         # Note: user_stability shouldn't really be here
 654
 655         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 656                      'requires', 'metadata', 'download_sources', 'commands',
 657                      'id', 'feed', 'version', 'released', 'bindings', 'machine']
 658
 659         def __init__(self, feed, id):
 660                 assert id
 661                 self.feed = feed
 662                 self.id = id
 663                 self.user_stability = None
 664                 self.upstream_stability = None
 665                 self.metadata = {}      # [URI + " "] + localName -> value
 666                 self.requires = []
 667                 self.version = None
 668                 self.released = None
 669                 self.download_sources = []
 670                 self.langs = ""
 671                 self.machine = None
 672                 self.bindings = []
 673                 self.commands = {}
 674
 675         def get_stability(self):
 676                 return self.user_stability or self.upstream_stability or testing
 677
 678         def __str__(self):
 679                 return self.id
 680
 681         def __repr__(self):
 682                 return "v%s (%s)" % (self.get_version(), self.id)
 683
 684         def __cmp__(self, other):
 685                 """Newer versions come first"""
 686                 d = cmp(other.version, self.version)
 687                 if d: return d
 688                 # If the version number is the same, just give a stable sort order, and
 689                 # ensure that two different implementations don't compare equal.
 690                 d = cmp(other.feed.url, self.feed.url)
 691                 if d: return d
 692                 return cmp(other.id, self.id)
 693
 694         def __hash__(self):
 695                 return self.id.__hash__()
 696
 697         def __eq__(self, other):
 698                 return self is other
 699
 700         def __le__(self, other):
 701                 if isinstance(other, Implementation):
 702                         if other.version < self.version: return True
 703                         elif other.version > self.version: return False
 704
 705                         if other.feed.url < self.feed.url: return True
 706                         elif other.feed.url > self.feed.url: return False
 707
 708                         return other.id <= self.id
 709                 else:
 710                         return NotImplemented
 711
 712         def get_version(self):
 713                 """Return the version as a string.
 714                 @see: L{format_version}
 715                 """
 716                 return format_version(self.version)
 717
 718         arch = property(lambda self: _join_arch(self.os, self.machine))
 719
 720         os = None
 721         local_path = None
 722         digests = None
 723         requires_root_install = False
 724
 725         def _get_main(self):
 726                 """"@deprecated: use commands["run"] instead"""
 727                 main = self.commands.get("run", None)
 728                 if main is not None:
 729                         return main.path
 730                 return None
 731         def _set_main(self, path):
 732                 """"@deprecated: use commands["run"] instead"""
 733                 if path is None:
 734                         if "run" in self.commands:
 735                                 del self.commands["run"]
 736                 else:
 737                         self.commands["run"] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': path, 'name': 'run'}), None)
 738         main = property(_get_main, _set_main)
 739
 740         def is_available(self, stores):
 741                 """Is this Implementation available locally?
 742                 (a local implementation, an installed distribution package, or a cached ZeroInstallImplementation)
 743                 @rtype: bool
 744                 @since: 0.53
 745                 """
 746                 raise NotImplementedError("abstract")
 747
 748 class DistributionImplementation(Implementation):
 749         """An implementation provided by the distribution. Information such as the version
 750         comes from the package manager.
 751         @ivar package_implementation: the <package-implementation> element that generated this impl (since 1.7)
 752         @type package_implementation: L{qdom.Element}
 753         @since: 0.28"""
 754         __slots__ = ['distro', 'installed', 'package_implementation']
 755
 756         def __init__(self, feed, id, distro, package_implementation = None):
 757                 assert id.startswith('package:')
 758                 Implementation.__init__(self, feed, id)
 759                 self.distro = distro
 760                 self.installed = False
 761                 self.package_implementation = package_implementation
 762
 763                 if package_implementation:
 764                         for child in package_implementation.childNodes:
 765                                 if child.uri != XMLNS_IFACE: continue
 766                                 if child.name == 'command':
 767                                         command_name = child.attrs.get('name', None)
 768                                         if not command_name:
 769                                                 raise InvalidInterface('Missing name for <command>')
 770                                         self.commands[command_name] = Command(child, local_dir = None)
 771
 772         @property
 773         def requires_root_install(self):
 774                 return not self.installed
 775
 776         def is_available(self, stores):
 777                 return self.installed
 778
 779 class ZeroInstallImplementation(Implementation):
 780         """An implementation where all the information comes from Zero Install.
 781         @ivar digests: a list of "algorith=value" or "algorith_value" strings (since 0.45)
 782         @type digests: [str]
 783         @since: 0.28"""
 784         __slots__ = ['os', 'size', 'digests', 'local_path']
 785
 786         def __init__(self, feed, id, local_path):
 787                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 788                 assert not id.startswith('package:'), id
 789                 Implementation.__init__(self, feed, id)
 790                 self.size = None
 791                 self.os = None
 792                 self.digests = []
 793                 self.local_path = local_path
 794
 795         # Deprecated
 796         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 797                                                    if isinstance(x, InterfaceRestriction)]))
 798
 799         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 800                 """Add a download source."""
 801                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 802
 803         def set_arch(self, arch):
 804                 self.os, self.machine = _split_arch(arch)
 805         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 806
 807         def is_available(self, stores):
 808                 if self.local_path is not None:
 809                         return os.path.exists(self.local_path)
 810                 if self.digests:
 811                         path = stores.lookup_maybe(self.digests)
 812                         return path is not None
 813                 return False    # (0compile creates fake entries with no digests)
 814
 815 class Interface(object):
 816         """An Interface represents some contract of behaviour.
 817         @ivar uri: the URI for this interface.
 818         @ivar stability_policy: user's configured policy.
 819         Implementations at this level or higher are preferred.
 820         Lower levels are used only if there is no other choice.
 821         """
 822         __slots__ = ['uri', 'stability_policy', 'extra_feeds']
 823
 824         implementations = property(lambda self: self._main_feed.implementations)
 825         name = property(lambda self: self._main_feed.name)
 826         description = property(lambda self: self._main_feed.description)
 827         summary = property(lambda self: self._main_feed.summary)
 828         last_modified = property(lambda self: self._main_feed.last_modified)
 829         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 830         metadata = property(lambda self: self._main_feed.metadata)
 831
 832         last_checked = property(lambda self: self._main_feed.last_checked)
 833
 834         def __init__(self, uri):
 835                 assert uri
 836                 if uri.startswith('http:') or uri.startswith('https:') or os.path.isabs(uri):
 837                         self.uri = uri
 838                 else:
 839                         raise SafeException(_("Interface name '%s' doesn't start "
 840                                             "with 'http:' or 'https:'") % uri)
 841                 self.reset()
 842
 843         def _get_feed_for(self):
 844                 retval = {}
 845                 for key in self._main_feed.feed_for:
 846                         retval[key] = True
 847                 return retval
 848         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 849
 850         def reset(self):
 851                 self.extra_feeds = []
 852                 self.stability_policy = None
 853
 854         def get_name(self):
 855                 from zeroinstall.injector.iface_cache import iface_cache
 856                 feed = iface_cache.get_feed(self.uri)
 857                 if feed:
 858                         return feed.get_name()
 859                 return '(' + os.path.basename(self.uri) + ')'
 860
 861         def __repr__(self):
 862                 return _("<Interface %s>") % self.uri
 863
 864         def set_stability_policy(self, new):
 865                 assert new is None or isinstance(new, Stability)
 866                 self.stability_policy = new
 867
 868         def get_feed(self, url):
 869                 #import warnings
 870                 #warnings.warn("use iface_cache.get_feed instead", DeprecationWarning, 2)
 871                 for x in self.extra_feeds:
 872                         if x.uri == url:
 873                                 return x
 874                 #return self._main_feed.get_feed(url)
 875                 return None
 876
 877         def get_metadata(self, uri, name):
 878                 return self._main_feed.get_metadata(uri, name)
 879
 880         @property
 881         def _main_feed(self):
 882                 #import warnings
 883                 #warnings.warn("use the feed instead", DeprecationWarning, 3)
 884                 from zeroinstall.injector import policy
 885                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
 886                 feed = iface_cache.get_feed(self.uri)
 887                 if feed is None:
 888                         return _dummy_feed
 889                 return feed
 890
 891 def _merge_attrs(attrs, item):
 892         """Add each attribute of item to a copy of attrs and return the copy.
 893         @type attrs: {str: str}
 894         @type item: L{qdom.Element}
 895         @rtype: {str: str}
 896         """
 897         new = attrs.copy()
 898         for a in item.attrs:
 899                 new[str(a)] = item.attrs[a]
 900         return new
 901
 902 def _get_long(elem, attr_name):
 903         val = elem.getAttribute(attr_name)
 904         if val is not None:
 905                 try:
 906                         val = int(val)
 907                 except ValueError:
 908                         raise SafeException(_("Invalid value for integer attribute '%(attribute_name)s': %(value)s") % {'attribute_name': attr_name, 'value': val})
 909         return val
 910
 911 class ZeroInstallFeed(object):
 912         """A feed lists available implementations of an interface.
 913         @ivar url: the URL for this feed
 914         @ivar implementations: Implementations in this feed, indexed by ID
 915         @type implementations: {str: L{Implementation}}
 916         @ivar name: human-friendly name
 917         @ivar summaries: short textual description (in various languages, since 0.49)
 918         @type summaries: {str: str}
 919         @ivar descriptions: long textual description (in various languages, since 0.49)
 920         @type descriptions: {str: str}
 921         @ivar last_modified: timestamp on signature
 922         @ivar last_checked: time feed was last successfully downloaded and updated
 923         @ivar local_path: the path of this local feed, or None if remote (since 1.7)
 924         @type local_path: str | None
 925         @ivar feeds: list of <feed> elements in this feed
 926         @type feeds: [L{Feed}]
 927         @ivar feed_for: interfaces for which this could be a feed
 928         @type feed_for: set(str)
 929         @ivar metadata: extra elements we didn't understand
 930         """
 931         # _main is deprecated
 932         __slots__ = ['url', 'implementations', 'name', 'descriptions', 'first_description', 'summaries', 'first_summary', '_package_implementations',
 933                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata', 'local_path']
 934
 935         def __init__(self, feed_element, local_path = None, distro = None):
 936                 """Create a feed object from a DOM.
 937                 @param feed_element: the root element of a feed file
 938                 @type feed_element: L{qdom.Element}
 939                 @param local_path: the pathname of this local feed, or None for remote feeds"""
 940                 self.local_path = local_path
 941                 self.implementations = {}
 942                 self.name = None
 943                 self.summaries = {}     # { lang: str }
 944                 self.first_summary = None
 945                 self.descriptions = {}  # { lang: str }
 946                 self.first_description = None
 947                 self.last_modified = None
 948                 self.feeds = []
 949                 self.feed_for = set()
 950                 self.metadata = []
 951                 self.last_checked = None
 952                 self._package_implementations = []
 953
 954                 if distro is not None:
 955                         import warnings
 956                         warnings.warn("distro argument is now ignored", DeprecationWarning, 2)
 957
 958                 if feed_element is None:
 959                         return                  # XXX subclass?
 960
 961                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 962                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 963
 964                 main = feed_element.getAttribute('main')
 965                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 966
 967                 if local_path:
 968                         self.url = local_path
 969                         local_dir = os.path.dirname(local_path)
 970                 else:
 971                         assert local_path is None
 972                         self.url = feed_element.getAttribute('uri')
 973                         if not self.url:
 974                                 raise InvalidInterface(_("<interface> uri attribute missing"))
 975                         local_dir = None        # Can't have relative paths
 976
 977                 min_injector_version = feed_element.getAttribute('min-injector-version')
 978                 if min_injector_version:
 979                         if parse_version(min_injector_version) > parse_version(version):
 980                                 raise InvalidInterface(_("This feed requires version %(min_version)s or later of "
 981                                                         "Zero Install, but I am only version %(version)s. "
 982                                                         "You can get a newer version from http://0install.net") %
 983                                                         {'min_version': min_injector_version, 'version': version})
 984
 985                 for x in feed_element.childNodes:
 986                         if x.uri != XMLNS_IFACE:
 987                                 self.metadata.append(x)
 988                                 continue
 989                         if x.name == 'name':
 990                                 self.name = x.content
 991                         elif x.name == 'description':
 992                                 if self.first_description == None:
 993                                         self.first_description = x.content
 994                                 self.descriptions[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 995                         elif x.name == 'summary':
 996                                 if self.first_summary == None:
 997                                         self.first_summary = x.content
 998                                 self.summaries[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 999                         elif x.name == 'feed-for':
1000                                 feed_iface = x.getAttribute('interface')
1001                                 if not feed_iface:
1002                                         raise InvalidInterface(_('Missing "interface" attribute in <feed-for>'))
1003                                 self.feed_for.add(feed_iface)
1004                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
1005                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
1006                                 # in case it happens again.
1007                                 debug(_("Is feed-for %s"), feed_iface)
1008                         elif x.name == 'feed':
1009                                 feed_src = x.getAttribute('src')
1010                                 if not feed_src:
1011                                         raise InvalidInterface(_('Missing "src" attribute in <feed>'))
1012                                 if feed_src.startswith('http:') or feed_src.startswith('https:') or local_path:
1013                                         if feed_src.startswith('.'):
1014                                                 feed_src = os.path.abspath(os.path.join(local_dir, feed_src))
1015
1016                                         langs = x.getAttribute('langs')
1017                                         if langs: langs = langs.replace('_', '-')
1018                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = langs))
1019                                 else:
1020                                         raise InvalidInterface(_("Invalid feed URL '%s'") % feed_src)
1021                         else:
1022                                 self.metadata.append(x)
1023
1024                 if not self.name:
1025                         raise InvalidInterface(_("Missing <name> in feed"))
1026                 if not self.summary:
1027                         raise InvalidInterface(_("Missing <summary> in feed"))
1028
1029                 def process_group(group, group_attrs, base_depends, base_bindings, base_commands):
1030                         for item in group.childNodes:
1031                                 if item.uri != XMLNS_IFACE: continue
1032
1033                                 if item.name not in ('group', 'implementation', 'package-implementation'):
1034                                         continue
1035
1036                                 # We've found a group or implementation. Scan for dependencies,
1037                                 # bindings and commands. Doing this here means that:
1038                                 # - We can share the code for groups and implementations here.
1039                                 # - The order doesn't matter, because these get processed first.
1040                                 # A side-effect is that the document root cannot contain
1041                                 # these.
1042
1043                                 depends = base_depends[:]
1044                                 bindings = base_bindings[:]
1045                                 commands = base_commands.copy()
1046
1047                                 for attr, command in [('main', 'run'),
1048                                                       ('self-test', 'test')]:
1049                                         value = item.attrs.get(attr, None)
1050                                         if value is not None:
1051                                                 commands[command] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': command, 'path': value}), None)
1052
1053                                 for child in item.childNodes:
1054                                         if child.uri != XMLNS_IFACE: continue
1055                                         if child.name in _dependency_names:
1056                                                 dep = process_depends(child, local_dir)
1057                                                 depends.append(dep)
1058                                         elif child.name == 'command':
1059                                                 command_name = child.attrs.get('name', None)
1060                                                 if not command_name:
1061                                                         raise InvalidInterface('Missing name for <command>')
1062                                                 commands[command_name] = Command(child, local_dir)
1063                                         elif child.name in binding_names:
1064                                                 bindings.append(process_binding(child))
1065
1066                                 compile_command = item.attrs.get('http://zero-install.sourceforge.net/2006/namespaces/0compile command')
1067                                 if compile_command is not None:
1068                                         commands['compile'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': 'compile', 'shell-command': compile_command}), None)
1069
1070                                 item_attrs = _merge_attrs(group_attrs, item)
1071
1072                                 if item.name == 'group':
1073                                         process_group(item, item_attrs, depends, bindings, commands)
1074                                 elif item.name == 'implementation':
1075                                         process_impl(item, item_attrs, depends, bindings, commands)
1076                                 elif item.name == 'package-implementation':
1077                                         if depends:
1078                                                 warn("A <package-implementation> with dependencies in %s!", self.url)
1079                                         self._package_implementations.append((item, item_attrs))
1080                                 else:
1081                                         assert 0
1082
1083                 def process_impl(item, item_attrs, depends, bindings, commands):
1084                         id = item.getAttribute('id')
1085                         if id is None:
1086                                 raise InvalidInterface(_("Missing 'id' attribute on %s") % item)
1087                         local_path = item_attrs.get('local-path')
1088                         if local_dir and local_path:
1089                                 abs_local_path = os.path.abspath(os.path.join(local_dir, local_path))
1090                                 impl = ZeroInstallImplementation(self, id, abs_local_path)
1091                         elif local_dir and (id.startswith('/') or id.startswith('.')):
1092                                 # For old feeds
1093                                 id = os.path.abspath(os.path.join(local_dir, id))
1094                                 impl = ZeroInstallImplementation(self, id, id)
1095                         else:
1096                                 impl = ZeroInstallImplementation(self, id, None)
1097                                 if '=' in id:
1098                                         # In older feeds, the ID was the (single) digest
1099                                         impl.digests.append(id)
1100                         if id in self.implementations:
1101                                 warn(_("Duplicate ID '%(id)s' in feed '%(feed)s'"), {'id': id, 'feed': self})
1102                         self.implementations[id] = impl
1103
1104                         impl.metadata = item_attrs
1105                         try:
1106                                 version_mod = item_attrs.get('version-modifier', None)
1107                                 if version_mod:
1108                                         item_attrs['version'] += version_mod
1109                                         del item_attrs['version-modifier']
1110                                 version = item_attrs['version']
1111                         except KeyError:
1112                                 raise InvalidInterface(_("Missing version attribute"))
1113                         impl.version = parse_version(version)
1114
1115                         impl.commands = commands
1116
1117                         impl.released = item_attrs.get('released', None)
1118                         impl.langs = item_attrs.get('langs', '').replace('_', '-')
1119
1120                         size = item.getAttribute('size')
1121                         if size:
1122                                 impl.size = int(size)
1123                         impl.arch = item_attrs.get('arch', None)
1124                         try:
1125                                 stability = stability_levels[str(item_attrs['stability'])]
1126                         except KeyError:
1127                                 stab = str(item_attrs['stability'])
1128                                 if stab != stab.lower():
1129                                         raise InvalidInterface(_('Stability "%s" invalid - use lower case!') % item_attrs.stability)
1130                                 raise InvalidInterface(_('Stability "%s" invalid') % item_attrs['stability'])
1131                         if stability >= preferred:
1132                                 raise InvalidInterface(_("Upstream can't set stability to preferred!"))
1133                         impl.upstream_stability = stability
1134
1135                         impl.bindings = bindings
1136                         impl.requires = depends
1137
1138                         for elem in item.childNodes:
1139                                 if elem.uri != XMLNS_IFACE: continue
1140                                 if elem.name == 'archive':
1141                                         url = elem.getAttribute('href')
1142                                         if not url:
1143                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1144                                         size = elem.getAttribute('size')
1145                                         if not size:
1146                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1147                                         impl.add_download_source(url = url, size = int(size),
1148                                                         extract = elem.getAttribute('extract'),
1149                                                         start_offset = _get_long(elem, 'start-offset'),
1150                                                         type = elem.getAttribute('type'))
1151                                 elif elem.name == 'manifest-digest':
1152                                         for aname, avalue in elem.attrs.items():
1153                                                 if ' ' not in aname:
1154                                                         impl.digests.append(zerostore.format_algorithm_digest_pair(aname, avalue))
1155                                 elif elem.name == 'recipe':
1156                                         recipe = Recipe()
1157                                         for recipe_step in elem.childNodes:
1158                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
1159                                                         url = recipe_step.getAttribute('href')
1160                                                         if not url:
1161                                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1162                                                         size = recipe_step.getAttribute('size')
1163                                                         if not size:
1164                                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1165                                                         recipe.steps.append(DownloadSource(None, url = url, size = int(size),
1166                                                                         extract = recipe_step.getAttribute('extract'),
1167                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
1168                                                                         type = recipe_step.getAttribute('type')))
1169                                                 elif recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'rename':
1170                                                         source = recipe_step.getAttribute('source')
1171                                                         if not source:
1172                                                                 raise InvalidInterface(_("Missing source attribute on <rename>"))
1173                                                         dest = recipe_step.getAttribute('dest')
1174                                                         if not dest:
1175                                                                 raise InvalidInterface(_("Missing dest attribute on <rename>"))
1176                                                         recipe.steps.append(RenameStep(source=source, dest=dest))
1177                                                 else:
1178                                                         info(_("Unknown step '%s' in recipe; skipping recipe"), recipe_step.name)
1179                                                         break
1180                                         else:
1181                                                 impl.download_sources.append(recipe)
1182
1183                 root_attrs = {'stability': 'testing'}
1184                 root_commands = {}
1185                 if main:
1186                         info("Note: @main on document element is deprecated in %s", self)
1187                         root_commands['run'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': main, 'name': 'run'}), None)
1188                 process_group(feed_element, root_attrs, [], [], root_commands)
1189
1190         def get_distro_feed(self):
1191                 """Does this feed contain any <pacakge-implementation> elements?
1192                 i.e. is it worth asking the package manager for more information?
1193                 @return: the URL of the virtual feed, or None
1194                 @since: 0.49"""
1195                 if self._package_implementations:
1196                         return "distribution:" + self.url
1197                 return None
1198
1199         def get_package_impls(self, distro):
1200                 """Find the best <pacakge-implementation> element(s) for the given distribution.
1201                 @param distro: the distribution to use to rate them
1202                 @type distro: L{distro.Distribution}
1203                 @return: a list of tuples for the best ranked elements
1204                 @rtype: [str]
1205                 @since: 0.49"""
1206                 best_score = 0
1207                 best_impls = []
1208
1209                 for item, item_attrs in self._package_implementations:
1210                         distro_names = item_attrs.get('distributions', '')
1211                         added_this = False
1212                         for distro_name in distro_names.split(' '):
1213                                 score = distro.get_score(distro_name) if distro_name else 0.5
1214                                 if score > best_score:
1215                                         best_score = score
1216                                         best_impls = []
1217                                 if score == best_score and not added_this:
1218                                         best_impls.append((item, item_attrs))
1219                                         added_this = True
1220                 return best_impls
1221
1222         def get_name(self):
1223                 return self.name or '(' + os.path.basename(self.url) + ')'
1224
1225         def __repr__(self):
1226                 return _("<Feed %s>") % self.url
1227
1228         def set_stability_policy(self, new):
1229                 assert new is None or isinstance(new, Stability)
1230                 self.stability_policy = new
1231
1232         def get_feed(self, url):
1233                 for x in self.feeds:
1234                         if x.uri == url:
1235                                 return x
1236                 return None
1237
1238         def add_metadata(self, elem):
1239                 self.metadata.append(elem)
1240
1241         def get_metadata(self, uri, name):
1242                 """Return a list of interface metadata elements with this name and namespace URI."""
1243                 return [m for m in self.metadata if m.name == name and m.uri == uri]
1244
1245         @property
1246         def summary(self):
1247                 return _best_language_match(self.summaries) or self.first_summary
1248
1249         @property
1250         def description(self):
1251                 return _best_language_match(self.descriptions) or self.first_description
1252
1253         def get_replaced_by(self):
1254                 """Return the URI of the interface that replaced the one with the URI of this feed's URL.
1255                 This is the value of the feed's <replaced-by interface'...'/> element.
1256                 @return: the new URI, or None if it hasn't been replaced
1257                 @since: 1.7"""
1258                 for child in self.metadata:
1259                         if child.uri == XMLNS_IFACE and child.name == 'replaced-by':
1260                                 new_uri = child.getAttribute('interface')
1261                                 if new_uri and (new_uri.startswith('http:') or new_uri.startswith('https:') or self.local_path):
1262                                         return new_uri
1263                 return None
1264
1265 class DummyFeed(object):
1266         """Temporary class used during API transition."""
1267         last_modified = None
1268         name = '-'
1269         last_checked = property(lambda self: None)
1270         implementations = property(lambda self: {})
1271         feeds = property(lambda self: [])
1272         summary = property(lambda self: '-')
1273         description = property(lambda self: '')
1274         def get_name(self): return self.name
1275         def get_feed(self, url): return None
1276         def get_metadata(self, uri, name): return []
1277 _dummy_feed = DummyFeed()
1278
1279 if sys.version_info[0] > 2:
1280         # Python 3
1281
1282         from functools import total_ordering
1283         Stability = total_ordering(Stability)
1284         Implementation = total_ordering(Implementation)
1285
1286         # These could be replaced by urllib.parse.quote, except that
1287         # it uses upper-case escapes and we use lower-case ones...
1288         def unescape(uri):
1289                 """Convert each %20 to a space, etc.
1290                 @rtype: str"""
1291                 uri = uri.replace('#', '/')
1292                 if '%' not in uri: return uri
1293                 return re.sub(b'%[0-9a-fA-F][0-9a-fA-F]',
1294                         lambda match: bytes([int(match.group(0)[1:], 16)]),
1295                         uri.encode('ascii')).decode('utf-8')
1296
1297         def escape(uri):
1298                 """Convert each space to %20, etc
1299                 @rtype: str"""
1300                 return re.sub(b'[^-_.a-zA-Z0-9]',
1301                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1302                         uri.encode('utf-8')).decode('ascii')
1303
1304         def _pretty_escape(uri):
1305                 """Convert each space to %20, etc
1306                 : is preserved and / becomes #. This makes for nicer strings,
1307                 and may replace L{escape} everywhere in future.
1308                 @rtype: str"""
1309                 if os.name == "posix":
1310                         # Only preserve : on Posix systems
1311                         preserveRegex = b'[^-_.a-zA-Z0-9:/]'
1312                 else:
1313                         # Other OSes may not allow the : character in file names
1314                         preserveRegex = b'[^-_.a-zA-Z0-9/]'
1315                 return re.sub(preserveRegex,
1316                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1317                         uri.encode('utf-8')).decode('ascii').replace('/', '#')
1318 else:
1319         # Python 2
1320
1321         def unescape(uri):
1322                 """Convert each %20 to a space, etc.
1323                 @rtype: str"""
1324                 uri = uri.replace('#', '/')
1325                 if '%' not in uri: return uri
1326                 return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
1327                         lambda match: chr(int(match.group(0)[1:], 16)),
1328                         uri).decode('utf-8')
1329
1330         def escape(uri):
1331                 """Convert each space to %20, etc
1332                 @rtype: str"""
1333                 return re.sub('[^-_.a-zA-Z0-9]',
1334                         lambda match: '%%%02x' % ord(match.group(0)),
1335                         uri.encode('utf-8'))
1336
1337         def _pretty_escape(uri):
1338                 """Convert each space to %20, etc
1339                 : is preserved and / becomes #. This makes for nicer strings,
1340                 and may replace L{escape} everywhere in future.
1341                 @rtype: str"""
1342                 if os.name == "posix":
1343                         # Only preserve : on Posix systems
1344                         preserveRegex = '[^-_.a-zA-Z0-9:/]'
1345                 else:
1346                         # Other OSes may not allow the : character in file names
1347                         preserveRegex = '[^-_.a-zA-Z0-9/]'
1348                 return re.sub(preserveRegex,
1349                         lambda match: '%%%02x' % ord(match.group(0)),
1350                         uri.encode('utf-8')).replace('/', '#')
1351
1352 def canonical_iface_uri(uri):
1353         """If uri is a relative path, convert to an absolute one.
1354         A "file:///foo" URI is converted to "/foo".
1355         An "alias:prog" URI expands to the URI in the 0alias script
1356         Otherwise, return it unmodified.
1357         @rtype: str
1358         @raise SafeException: if uri isn't valid
1359         """
1360         if uri.startswith('http://') or uri.startswith('https://'):
1361                 if uri.count("/") < 3:
1362                         raise SafeException(_("Missing / after hostname in URI '%s'") % uri)
1363                 return uri
1364         elif uri.startswith('file:///'):
1365                 path = uri[7:]
1366         elif uri.startswith('file:'):
1367                 if uri[5] == '/':
1368                         raise SafeException(_('Use file:///path for absolute paths, not {uri}').format(uri = uri))
1369                 path = os.path.abspath(uri[5:])
1370         elif uri.startswith('alias:'):
1371                 from zeroinstall import alias
1372                 alias_prog = uri[6:]
1373                 if not os.path.isabs(alias_prog):
1374                         full_path = support.find_in_path(alias_prog)
1375                         if not full_path:
1376                                 raise alias.NotAnAliasScript("Not found in $PATH: " + alias_prog)
1377                 else:
1378                         full_path = alias_prog
1379                 return alias.parse_script(full_path).uri
1380         else:
1381                 path = os.path.realpath(uri)
1382
1383         if os.path.isfile(path):
1384                 return path
1385         raise SafeException(_("Bad interface name '%(uri)s'.\n"
1386                         "(doesn't start with 'http:', and "
1387                         "doesn't exist as a local file '%(interface_uri)s' either)") %
1388                         {'uri': uri, 'interface_uri': path})
1389
1390 _version_mod_to_value = {
1391         'pre': -2,
1392         'rc': -1,
1393         '': 0,
1394         'post': 1,
1395 }
1396
1397 # Reverse mapping
1398 _version_value_to_mod = {}
1399 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
1400 del x
1401
1402 _version_re = re.compile('-([a-z]*)')
1403
1404 def parse_version(version_string):
1405         """Convert a version string to an internal representation.
1406         The parsed format can be compared quickly using the standard Python functions.
1407          - Version := DottedList ("-" Mod DottedList?)*
1408          - DottedList := (Integer ("." Integer)*)
1409         @rtype: tuple (opaque)
1410         @raise SafeException: if the string isn't a valid version
1411         @since: 0.24 (moved from L{reader}, from where it is still available):"""
1412         if version_string is None: return None
1413         parts = _version_re.split(version_string)
1414         if parts[-1] == '':
1415                 del parts[-1]   # Ends with a modifier
1416         else:
1417                 parts.append('')
1418         if not parts:
1419                 raise SafeException(_("Empty version string!"))
1420         l = len(parts)
1421         try:
1422                 for x in range(0, l, 2):
1423                         part = parts[x]
1424                         if part:
1425                                 parts[x] = list(map(int, parts[x].split('.')))
1426                         else:
1427                                 parts[x] = []   # (because ''.split('.') == [''], not [])
1428                 for x in range(1, l, 2):
1429                         parts[x] = _version_mod_to_value[parts[x]]
1430                 return parts
1431         except ValueError as ex:
1432                 raise SafeException(_("Invalid version format in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1433         except KeyError as ex:
1434                 raise SafeException(_("Invalid version modifier in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1435
1436 def format_version(version):
1437         """Format a parsed version for display. Undoes the effect of L{parse_version}.
1438         @see: L{Implementation.get_version}
1439         @rtype: str
1440         @since: 0.24"""
1441         version = version[:]
1442         l = len(version)
1443         for x in range(0, l, 2):
1444                 version[x] = '.'.join(map(str, version[x]))
1445         for x in range(1, l, 2):
1446                 version[x] = '-' + _version_value_to_mod[version[x]]
1447         if version[-1] == '-': del version[-1]
1448         return ''.join(version)
1449