Esempio n. 1
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        def loadXml(self, xpackage):
            self.packageName = xpackage.Attribute('name')
            self.platform = xpackage.Attribute('platform')
            self.version = xpackage.Attribute('version')
            solo = xpackage.Attribute('solo')
            self.solo = int(solo or '0')
            perPlatform = xpackage.Attribute('per_platform')
            self.perPlatform = int(perPlatform or '0')

            self.descFile = FileSpec()
            self.descFile.loadXml(xpackage)

            self.validatePackageContents()

            self.descFile.quickVerify(packageDir=self.sourceDir,
                                      notify=PackageMerger.notify,
                                      correctSelf=True)

            self.packageSeq = SeqValue()
            self.packageSeq.loadXml(xpackage, 'seq')
            self.packageSetVer = SeqValue()
            self.packageSetVer.loadXml(xpackage, 'set_ver')

            self.importDescFile = None
            ximport = xpackage.FirstChildElement('import')
            if ximport:
                self.importDescFile = FileSpec()
                self.importDescFile.loadXml(ximport)
                self.importDescFile.quickVerify(packageDir=self.sourceDir,
                                                notify=PackageMerger.notify,
                                                correctSelf=True)
Esempio n. 2
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        def validatePackageContents(self):
            """ Validates the contents of the package directory itself
            against the expected hashes and timestamps.  Updates
            hashes and timestamps where needed. """

            if self.solo:
                return

            needsChange = False
            packageDescFullpath = Filename(self.sourceDir,
                                           self.descFile.filename)
            packageDir = Filename(packageDescFullpath.getDirname())
            doc = TiXmlDocument(packageDescFullpath.toOsSpecific())
            if not doc.LoadFile():
                message = "Could not read XML file: %s" % (
                    self.descFile.filename)
                raise OSError, message

            xpackage = doc.FirstChildElement('package')
            if not xpackage:
                message = "No package definition: %s" % (
                    self.descFile.filename)
                raise OSError, message

            xcompressed = xpackage.FirstChildElement('compressed_archive')
            if xcompressed:
                spec = FileSpec()
                spec.loadXml(xcompressed)
                if not spec.quickVerify(packageDir=packageDir,
                                        notify=PackageMerger.notify,
                                        correctSelf=True):
                    spec.storeXml(xcompressed)
                    needsChange = True

            xpatch = xpackage.FirstChildElement('patch')
            while xpatch:
                spec = FileSpec()
                spec.loadXml(xpatch)
                if not spec.quickVerify(packageDir=packageDir,
                                        notify=PackageMerger.notify,
                                        correctSelf=True):
                    spec.storeXml(xpatch)
                    needsChange = True

                xpatch = xpatch.NextSiblingElement('patch')

            if needsChange:
                PackageMerger.notify.info("Rewriting %s" %
                                          (self.descFile.filename))
                doc.SaveFile()
                self.descFile.quickVerify(packageDir=self.sourceDir,
                                          notify=PackageMerger.notify,
                                          correctSelf=True)
Esempio n. 3
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        def fromFile(self, packageDir, patchFilename, sourceFile, targetFile):
            """ Creates the data structures from an existing patchfile
            on disk. """

            self.file = FileSpec()
            self.file.fromFile(packageDir, patchFilename)
            self.sourceFile = sourceFile
            self.targetFile = targetFile
Esempio n. 4
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        def loadXml(self, xpatch):
            """ Reads the data structures from an xml file. """

            self.packageName = xpatch.Attribute('name') or self.packageName
            self.platform = xpatch.Attribute('platform') or self.platform
            self.version = xpatch.Attribute('version') or self.version
            self.hostUrl = xpatch.Attribute('host') or self.hostUrl

            self.file = FileSpec()
            self.file.loadXml(xpatch)

            xsource = xpatch.FirstChildElement('source')
            if xsource:
                self.sourceFile = FileSpec()
                self.sourceFile.loadXml(xsource)

            xtarget = xpatch.FirstChildElement('target')
            if xtarget:
                self.targetFile = FileSpec()
                self.targetFile.loadXml(xtarget)
        def loadXml(self, xpackage):
            self.packageName = xpackage.Attribute('name')
            self.platform = xpackage.Attribute('platform')
            self.version = xpackage.Attribute('version')
            solo = xpackage.Attribute('solo')
            self.solo = int(solo or '0')

            self.descFile = FileSpec()
            self.descFile.loadXml(xpackage)

            self.packageSeq = SeqValue()
            self.packageSeq.loadXml(xpackage, 'seq')
            self.packageSetVer = SeqValue()
            self.packageSetVer.loadXml(xpackage, 'set_ver')

            self.importDescFile = None
            ximport = xpackage.FirstChildElement('import')
            if ximport:
                self.importDescFile = FileSpec()
                self.importDescFile.loadXml(ximport)
Esempio n. 6
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        def writeDescFile(self):
            """ Rewrites the desc file with the new patch
            information. """

            if not self.anyChanges:
                # No need to rewrite.
                return

            xpackage = self.doc.FirstChildElement('package')
            if not xpackage:
                return

            packageSeq = SeqValue()
            packageSeq.loadXml(xpackage, 'seq')
            packageSeq += 1
            packageSeq.storeXml(xpackage, 'seq')

            # Remove all of the old patch entries from the desc file
            # we read earlier.
            xremove = []
            for value in ['base_version', 'top_version', 'patch']:
                xpatch = xpackage.FirstChildElement(value)
                while xpatch:
                    xremove.append(xpatch)
                    xpatch = xpatch.NextSiblingElement(value)

            for xelement in xremove:
                xpackage.RemoveChild(xelement)

            xpackage.RemoveAttribute('last_patch_version')

            # Now replace them with the current patch information.
            xpackage.SetAttribute('patch_version', str(self.patchVersion))

            xarchive = TiXmlElement('base_version')
            self.baseFile.storeXml(xarchive)
            xpackage.InsertEndChild(xarchive)

            # The current version is now the top version.
            xarchive = TiXmlElement('top_version')
            self.currentFile.storeXml(xarchive)
            xpackage.InsertEndChild(xarchive)

            for patchfile in self.patches:
                xpatch = patchfile.makeXml(self)
                xpackage.InsertEndChild(xpatch)

            self.doc.SaveFile()

            # Also copy the seq to the import desc file, for
            # documentation purposes.

            importDescFilename = str(self.packageDesc)[:-3] + 'import.xml'
            importDescFullpath = Filename(self.patchMaker.installDir,
                                          importDescFilename)
            doc = TiXmlDocument(importDescFullpath.toOsSpecific())
            if doc.LoadFile():
                xpackage = doc.FirstChildElement('package')
                if xpackage:
                    packageSeq.storeXml(xpackage, 'seq')
                    doc.SaveFile()
            else:
                print("Couldn't read %s" % (importDescFullpath))

            if self.contentsDocPackage:
                # Now that we've rewritten the xml file, we have to
                # change the contents.xml file that references it to
                # indicate the new file hash.
                fileSpec = FileSpec()
                fileSpec.fromFile(self.patchMaker.installDir, self.packageDesc)
                fileSpec.storeXml(self.contentsDocPackage)

                # Also important to update the import.xml hash.
                ximport = self.contentsDocPackage.FirstChildElement('import')
                if ximport:
                    fileSpec = FileSpec()
                    fileSpec.fromFile(self.patchMaker.installDir,
                                      importDescFilename)
                    fileSpec.storeXml(ximport)

                # Also copy the package seq value into the
                # contents.xml file, mainly for documentation purposes
                # (the authoritative seq value is within the desc
                # file).
                packageSeq.storeXml(self.contentsDocPackage, 'seq')
Esempio n. 7
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        def readDescFile(self, doProcessing=False):
            """ Reads the existing package.xml file and stores it in
            this class for later rewriting.  if doProcessing is true,
            it may massage the file and the directory contents in
            preparation for building patches.  Returns true on
            success, false on failure. """

            self.anyChanges = False

            packageDescFullpath = Filename(self.patchMaker.installDir,
                                           self.packageDesc)
            self.doc = TiXmlDocument(packageDescFullpath.toOsSpecific())
            if not self.doc.LoadFile():
                print("Couldn't read %s" % (packageDescFullpath))
                return False

            xpackage = self.doc.FirstChildElement('package')
            if not xpackage:
                return False
            self.packageName = xpackage.Attribute('name')
            self.platform = xpackage.Attribute('platform')
            self.version = xpackage.Attribute('version')

            # All packages we defined in-line are assigned to the
            # "none" host.  TODO: support patching from packages on
            # other hosts, which means we'll need to fill in a value
            # here for those hosts.
            self.hostUrl = None

            self.currentFile = None
            self.baseFile = None
            self.topFile = None
            self.compressedFilename = None
            compressedFile = None

            # Assume there are changes for this version, until we
            # discover that there aren't.
            isNewVersion = True

            # Get the actual current version.
            xarchive = xpackage.FirstChildElement('uncompressed_archive')
            if xarchive:
                self.currentFile = FileSpec()
                self.currentFile.loadXml(xarchive)

            # Get the top_version--the top (newest) of the patch
            # chain.
            xarchive = xpackage.FirstChildElement('top_version')
            if xarchive:
                self.topFile = FileSpec()
                self.topFile.loadXml(xarchive)

                if self.topFile.hash == self.currentFile.hash:
                    # No new version this pass.
                    isNewVersion = False
                else:
                    # There's a new version this pass.  Update it.
                    self.anyChanges = True

            else:
                # If there isn't a top_version yet, we have to make
                # one, by duplicating the currentFile.
                self.topFile = copy.copy(self.currentFile)
                self.anyChanges = True

            # Get the current patch version.  If we have a
            # patch_version attribute, it refers to this particular
            # instance of the file, and that is the current patch
            # version number.  If we only have a last_patch_version
            # attribute, it means a patch has not yet been built for
            # this particular instance, and that number is the
            # previous version's patch version number.
            patchVersion = xpackage.Attribute('patch_version')
            if patchVersion:
                self.patchVersion = int(patchVersion)
            else:
                patchVersion = xpackage.Attribute('last_patch_version')
                if patchVersion:
                    self.patchVersion = int(patchVersion)
                    if isNewVersion:
                        self.patchVersion += 1
                self.anyChanges = True

            # Put the patchVersion in the compressed filename, for
            # cache-busting.  This means when the version changes, its
            # URL will also change, guaranteeing that users will
            # download the latest version, and not some stale cache
            # file.
            xcompressed = xpackage.FirstChildElement('compressed_archive')
            if xcompressed:
                compressedFile = FileSpec()
                compressedFile.loadXml(xcompressed)

                oldCompressedFilename = compressedFile.filename
                self.compressedFilename = oldCompressedFilename

                if doProcessing:
                    newCompressedFilename = '%s.%s.pz' % (
                        self.currentFile.filename, self.patchVersion)
                    if newCompressedFilename != oldCompressedFilename:
                        oldCompressedPathname = Filename(
                            self.packageDir, oldCompressedFilename)
                        newCompressedPathname = Filename(
                            self.packageDir, newCompressedFilename)
                        if oldCompressedPathname.renameTo(
                                newCompressedPathname):
                            compressedFile.fromFile(self.packageDir,
                                                    newCompressedFilename)
                            compressedFile.storeXml(xcompressed)

                        self.compressedFilename = newCompressedFilename
                        self.anyChanges = True

            # Get the base_version--the bottom (oldest) of the patch
            # chain.
            xarchive = xpackage.FirstChildElement('base_version')
            if xarchive:
                self.baseFile = FileSpec()
                self.baseFile.loadXml(xarchive)
            else:
                # If there isn't a base_version yet, we have to make
                # one, by duplicating the currentFile.
                self.baseFile = copy.copy(self.currentFile)

                # Note that the we only store the compressed version
                # of base_filename on disk, but we store the md5 of
                # the uncompressed version in the xml file.  To
                # emphasize this, we name it without the .pz extension
                # in the xml file, even though the compressed file on
                # disk actually has a .pz extension.
                self.baseFile.filename += '.base'

                # Also duplicate the (compressed) file itself.
                if doProcessing and self.compressedFilename:
                    fromPathname = Filename(self.packageDir,
                                            self.compressedFilename)
                    toPathname = Filename(self.packageDir,
                                          self.baseFile.filename + '.pz')
                    fromPathname.copyTo(toPathname)
                self.anyChanges = True

            self.patches = []
            xpatch = xpackage.FirstChildElement('patch')
            while xpatch:
                patchfile = PatchMaker.Patchfile(self)
                patchfile.loadXml(xpatch)
                self.patches.append(patchfile)
                xpatch = xpatch.NextSiblingElement('patch')

            return True
Esempio n. 8
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    def readContentsFile(self, tempFilename = None, freshDownload = False):
        """ Reads the contents.xml file for this particular host, once
        it has been downloaded into the indicated temporary file.
        Returns true on success, false if the contents file is not
        already on disk or is unreadable.

        If tempFilename is specified, it is the filename read, and it
        is copied the file into the standard location if it's not
        there already.  If tempFilename is not specified, the standard
        filename is read if it is known. """

        if not hasattr(PandaModules, 'TiXmlDocument'):
            return False

        if not tempFilename:
            if self.hostDir:
                # If the filename is not specified, we can infer it
                # if we already know our hostDir
                hostDir = self.hostDir
            else:
                # Otherwise, we have to guess the hostDir.
                hostDir = self.__determineHostDir(None, self.hostUrl)

            tempFilename = Filename(hostDir, 'contents.xml')

        doc = PandaModules.TiXmlDocument(tempFilename.toOsSpecific())
        if not doc.LoadFile():
            return False

        xcontents = doc.FirstChildElement('contents')
        if not xcontents:
            return False

        maxAge = xcontents.Attribute('max_age')
        if maxAge:
            try:
                maxAge = int(maxAge)
            except:
                maxAge = None
        if maxAge is None:
            # Default max_age if unspecified (see p3d_plugin.h).
            from direct.p3d.AppRunner import AppRunner
            maxAge = AppRunner.P3D_CONTENTS_DEFAULT_MAX_AGE

        # Get the latest possible expiration time, based on the max_age
        # indication.  Any expiration time later than this is in error.
        now = int(time.time())
        self.contentsExpiration = now + maxAge

        if freshDownload:
            self.contentsSpec.readHash(tempFilename)

            # Update the XML with the new download information.
            xorig = xcontents.FirstChildElement('orig')
            while xorig:
                xcontents.RemoveChild(xorig)
                xorig = xcontents.FirstChildElement('orig')

            xorig = PandaModules.TiXmlElement('orig')
            self.contentsSpec.storeXml(xorig)
            xorig.SetAttribute('expiration', str(self.contentsExpiration))

            xcontents.InsertEndChild(xorig)
            
        else:
            # Read the download hash and expiration time from the XML.
            expiration = None
            xorig = xcontents.FirstChildElement('orig')
            if xorig:
                self.contentsSpec.loadXml(xorig)
                expiration = xorig.Attribute('expiration')
                if expiration:
                    try:
                        expiration = int(expiration)
                    except:
                        expiration = None
            if not self.contentsSpec.hash:
                self.contentsSpec.readHash(tempFilename)

            if expiration is not None:
                self.contentsExpiration = min(self.contentsExpiration, expiration)

        # Look for our own entry in the hosts table.
        if self.hostUrl:
            self.__findHostXml(xcontents)
        else:
            assert self.hostDir
            self.__findHostXmlForHostDir(xcontents)

        if not self.hostDir:
            self.hostDir = self.__determineHostDir(None, self.hostUrl)

        # Get the list of packages available for download and/or import.
        xpackage = xcontents.FirstChildElement('package')
        while xpackage:
            name = xpackage.Attribute('name')
            platform = xpackage.Attribute('platform')
            version = xpackage.Attribute('version')
            try:
                solo = int(xpackage.Attribute('solo') or '')
            except ValueError:
                solo = False
                
            package = self.__makePackage(name, platform, version, solo)
            package.descFile = FileSpec()
            package.descFile.loadXml(xpackage)
            package.setupFilenames()

            package.importDescFile = None
            ximport = xpackage.FirstChildElement('import')
            if ximport:
                package.importDescFile = FileSpec()
                package.importDescFile.loadXml(ximport)

            xpackage = xpackage.NextSiblingElement('package')

        self.hasContentsFile = True

        # Now save the contents.xml file into the standard location.
        if not self.appRunner or self.appRunner.verifyContents != self.appRunner.P3DVCNever:
            assert self.hostDir
            filename = Filename(self.hostDir, 'contents.xml')
            filename.makeDir()
            if freshDownload:
                doc.SaveFile(filename.toOsSpecific())
            else:
                if filename != tempFilename:
                    tempFilename.copyTo(filename)

        return True
Esempio n. 9
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    def __init__(self, hostUrl, appRunner = None, hostDir = None,
                 rootDir = None, asMirror = False, perPlatform = None):

        """ You must specify either an appRunner or a hostDir to the
        HostInfo constructor.

        If you pass asMirror = True, it means that this HostInfo
        object is to be used to populate a "mirror" folder, a
        duplicate (or subset) of the contents hosted by a server.
        This means when you use this HostInfo to download packages, it
        will only download the compressed archive file and leave it
        there.  At the moment, mirror folders do not download old
        patch files from the server.

        If you pass perPlatform = True, then files are unpacked into a
        platform-specific directory, which is appropriate when you
        might be downloading multiple platforms.  The default is
        perPlatform = False, which means all files are unpacked into
        the host directory directly, without an intervening
        platform-specific directory name.  If asMirror is True, then
        the default is perPlatform = True. """

        assert appRunner or rootDir or hostDir

        self.__setHostUrl(hostUrl)
        self.appRunner = appRunner
        self.rootDir = rootDir
        if rootDir is None and appRunner:
            self.rootDir = appRunner.rootDir

        if hostDir and not isinstance(hostDir, Filename):
            hostDir = Filename.fromOsSpecific(hostDir)
            
        self.hostDir = hostDir
        self.asMirror = asMirror
        self.perPlatform = perPlatform
        if perPlatform is None:
            self.perPlatform = asMirror

        # Initially false, this is set true when the contents file is
        # successfully read.
        self.hasContentsFile = False

        # This is the time value at which the current contents file is
        # no longer valid.
        self.contentsExpiration = 0

        # Contains the md5 hash of the original contents.xml file.
        self.contentsSpec = FileSpec()

        # descriptiveName will be filled in later, when the
        # contents file is read.
        self.descriptiveName = None

        # A list of known mirrors for this host, all URL's guaranteed
        # to end with a slash.
        self.mirrors = []

        # A map of keyword -> altHost URL's.  An altHost is different
        # than a mirror; an altHost is an alternate URL to download a
        # different (e.g. testing) version of this host's contents.
        # It is rarely used.
        self.altHosts = {}

        # This is a dictionary of packages by (name, version).  It
        # will be filled in when the contents file is read.
        self.packages = {}

        if self.appRunner and self.appRunner.verifyContents != self.appRunner.P3DVCForce:
            # Attempt to pre-read the existing contents.xml; maybe it
            # will be current enough for our purposes.
            self.readContentsFile()
Esempio n. 10
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    def __buildInstallPlans(self):
        """ Sets up self.installPlans, a list of one or more "plans"
        to download and install the package. """

        pc = PStatCollector(':App:PackageInstaller:buildInstallPlans')
        pc.start()

        self.hasPackage = False

        if self.host.appRunner and self.host.appRunner.verifyContents == self.host.appRunner.P3DVCNever:
            # We're not allowed to download anything.
            self.installPlans = []
            pc.stop()
            return

        if self.asMirror:
            # If we're just downloading a mirror archive, we only need
            # to get the compressed archive file.

            # Build a one-item install plan to download the compressed
            # archive.
            downloadSize = self.compressedArchive.size
            func = lambda step, fileSpec=self.compressedArchive: self.__downloadFile(
                step, fileSpec, allowPartial=True)

            step = self.InstallStep(func, downloadSize, self.downloadFactor,
                                    'download')
            installPlan = [step]
            self.installPlans = [installPlan]
            pc.stop()
            return

        # The normal download process.  Determine what we will need to
        # download, and build a plan (or two) to download it all.
        self.installPlans = None

        # We know we will at least need to unpack the archive contents
        # at the end.
        unpackSize = 0
        for file in self.extracts:
            unpackSize += file.size
        step = self.InstallStep(self.__unpackArchive, unpackSize,
                                self.unpackFactor, 'unpack')
        planA = [step]

        # If the uncompressed archive file is good, that's all we'll
        # need to do.
        self.uncompressedArchive.actualFile = None
        if self.uncompressedArchive.quickVerify(self.getPackageDir(),
                                                notify=self.notify):
            self.installPlans = [planA]
            pc.stop()
            return

        # Maybe the compressed archive file is good.
        if self.compressedArchive.quickVerify(self.getPackageDir(),
                                              notify=self.notify):
            uncompressSize = self.uncompressedArchive.size
            step = self.InstallStep(self.__uncompressArchive, uncompressSize,
                                    self.uncompressFactor, 'uncompress')
            planA = [step] + planA
            self.installPlans = [planA]
            pc.stop()
            return

        # Maybe we can download one or more patches.  We'll come back
        # to that in a minute as plan A.  For now, construct plan B,
        # which will be to download the whole archive.
        planB = planA[:]

        uncompressSize = self.uncompressedArchive.size
        step = self.InstallStep(self.__uncompressArchive, uncompressSize,
                                self.uncompressFactor, 'uncompress')
        planB = [step] + planB

        downloadSize = self.compressedArchive.size
        func = lambda step, fileSpec=self.compressedArchive: self.__downloadFile(
            step, fileSpec, allowPartial=True)

        step = self.InstallStep(func, downloadSize, self.downloadFactor,
                                'download')
        planB = [step] + planB

        # Now look for patches.  Start with the md5 hash from the
        # uncompressedArchive file we have on disk, and see if we can
        # find a patch chain from this file to our target.
        pathname = Filename(self.getPackageDir(),
                            self.uncompressedArchive.filename)
        fileSpec = self.uncompressedArchive.actualFile
        if fileSpec is None and pathname.exists():
            fileSpec = FileSpec()
            fileSpec.fromFile(self.getPackageDir(),
                              self.uncompressedArchive.filename)
        plan = None
        if fileSpec:
            plan = self.__findPatchChain(fileSpec)
        if plan:
            # We can download patches.  Great!  That means this is
            # plan A, and the full download is plan B (in case
            # something goes wrong with the patching).
            planA = plan + planA
            self.installPlans = [planA, planB]
        else:
            # There are no patches to download, oh well.  Stick with
            # plan B as the only plan.
            self.installPlans = [planB]

        # In case of unexpected failures on the internet, we will retry
        # the full download instead of just giving up.
        for retry in range(ConfigVariableInt('package-full-dl-retries', 1)):
            self.installPlans.append(planB[:])

        pc.stop()
Esempio n. 11
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    def __readDescFile(self):
        """ Reads the desc xml file for this particular package,
        assuming it's been already downloaded and verified.  Returns
        true on success, false on failure. """

        if self.hasDescFile:
            # No need to read it again.
            return True

        if self.solo:
            # If this is a "solo" package, we don't actually "read"
            # the desc file; that's the entire contents of the
            # package.
            self.hasDescFile = True
            self.hasPackage = True
            return True

        filename = Filename(self.getPackageDir(), self.descFileBasename)

        if not hasattr(PandaModules, 'TiXmlDocument'):
            return False
        doc = PandaModules.TiXmlDocument(filename.toOsSpecific())
        if not doc.LoadFile():
            return False

        xpackage = doc.FirstChildElement('package')
        if not xpackage:
            return False

        try:
            self.patchVersion = int(xpackage.Attribute('patch_version') or '')
        except ValueError:
            self.patchVersion = None

        self.displayName = None
        xconfig = xpackage.FirstChildElement('config')
        if xconfig:
            # The name for display to an English-speaking user.
            self.displayName = xconfig.Attribute('display_name')

            # True if any apps that use this package must be GUI apps.
            guiApp = xconfig.Attribute('gui_app')
            if guiApp:
                self.guiApp = int(guiApp)

        # The uncompressed archive, which will be mounted directly,
        # and also used for patching.
        xuncompressedArchive = xpackage.FirstChildElement(
            'uncompressed_archive')
        if xuncompressedArchive:
            self.uncompressedArchive = FileSpec()
            self.uncompressedArchive.loadXml(xuncompressedArchive)

        # The compressed archive, which is what is downloaded.
        xcompressedArchive = xpackage.FirstChildElement('compressed_archive')
        if xcompressedArchive:
            self.compressedArchive = FileSpec()
            self.compressedArchive.loadXml(xcompressedArchive)

        # The list of files that should be extracted to disk.
        self.extracts = []
        xextract = xpackage.FirstChildElement('extract')
        while xextract:
            file = FileSpec()
            file.loadXml(xextract)
            self.extracts.append(file)
            xextract = xextract.NextSiblingElement('extract')

        # The list of additional packages that must be installed for
        # this package to function properly.
        self.requires = []
        xrequires = xpackage.FirstChildElement('requires')
        while xrequires:
            packageName = xrequires.Attribute('name')
            version = xrequires.Attribute('version')
            hostUrl = xrequires.Attribute('host')
            if packageName and hostUrl:
                host = self.host.appRunner.getHostWithAlt(hostUrl)
                self.requires.append((packageName, version, host))
            xrequires = xrequires.NextSiblingElement('requires')

        self.hasDescFile = True

        # Now that we've read the desc file, go ahead and use it to
        # verify the download status.
        if self.__checkArchiveStatus():
            # It's all fully downloaded, unpacked, and ready.
            self.hasPackage = True
            return True

        # Still have to download it.
        self.__buildInstallPlans()
        return True