bundles/org.eclipse.equinox.p2.updatesite/src/org/eclipse/equinox/internal/p2/updatesite/UpdateSite.java - equinox/rt.equinox.p2 - Git at Google

 /*******************************************************************************
  *  Copyright (c) 2008, 2009 IBM Corporation and others.
  *  All rights reserved. This program and the accompanying materials
  *  are made available under the terms of the Eclipse Public License v1.0
  *  which accompanies this distribution, and is available at
  *  http://www.eclipse.org/legal/epl-v10.html
  *
  *  Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.equinox.internal.p2.updatesite;

 import java.io.*;
 import java.net.*;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.zip.*;
 import org.eclipse.core.runtime.*;
 import org.eclipse.ecf.filetransfer.UserCancelledException;
 import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
 import org.eclipse.equinox.internal.p2.publisher.eclipse.FeatureParser;
 import org.eclipse.equinox.internal.p2.repository.AuthenticationFailedException;
 import org.eclipse.equinox.internal.p2.repository.RepositoryTransport;
 import org.eclipse.equinox.internal.provisional.p2.core.ProvisionException;
 import org.eclipse.equinox.p2.publisher.eclipse.*;
 import org.eclipse.osgi.util.NLS;
 import org.xml.sax.SAXException;

 /**
  * @since 1.0
  */
 public class UpdateSite {

 	private static final String VERSION_SEPARATOR = "_"; //$NON-NLS-1$
 	private static final String JAR_EXTENSION = ".jar"; //$NON-NLS-1$
 	private static final String FEATURE_DIR = "features/"; //$NON-NLS-1$
 	private static final String PLUGIN_DIR = "plugins/"; //$NON-NLS-1$
 	private static final String FEATURE_TEMP_FILE = "feature"; //$NON-NLS-1$
 	private static final String SITE_FILE = "site.xml"; //$NON-NLS-1$
 	private static final String PROTOCOL_FILE = "file"; //$NON-NLS-1$
 	private static final int RETRY_COUNT = 2;
 	private static final String DOT_XML = ".xml"; //$NON-NLS-1$
 	private static final String SITE = "site"; //$NON-NLS-1$
 	private String checksum;
 	private URI location;
 	private URI rootLocation;
 	private SiteModel site;

 	/*
 	 * Some variables for caching.
 	 */
 	// map of String (URI.toString()) to UpdateSite
 	private static Map siteCache = new HashMap();
 	// map of String (featureID_featureVersion) to Feature
 	private Map featureCache = new HashMap();

 	/*
 	 * Return a URI based on the given URI, which points to a site.xml file.
 	 */
 	private static URI getSiteURI(URI baseLocation) {
 		String segment = URIUtil.lastSegment(baseLocation);
 		if (constainsUpdateSiteFileName(segment))
 			return baseLocation;
 		return URIUtil.append(baseLocation, SITE_FILE);
 	}

 	/**
 	 * Be lenient about accepting any location with *site*.xml at the end.
 	 */
 	private static boolean constainsUpdateSiteFileName(String segment) {
 		return segment != null && segment.endsWith(DOT_XML) && segment.indexOf(SITE) != -1;
 	}

 	/**
 	 * Loads and returns a category file
 	 * @param location
 	 * @param monitor
 	 * @return A CategoryFile
 	 * @throws ProvisionException
 	 */
 	public static synchronized UpdateSite loadCategoryFile(URI location, IProgressMonitor monitor) throws ProvisionException {
 		if (location == null)
 			return null;
 		UpdateSite result = (UpdateSite) siteCache.get(location.toString());
 		if (result != null)
 			return result;
 		InputStream input = null;
 		File siteFile = loadActualSiteFile(location, location, monitor);
 		try {
 			DefaultSiteParser siteParser = new DefaultSiteParser(location);
 			Checksum checksum = new CRC32();
 			input = new CheckedInputStream(new BufferedInputStream(new FileInputStream(siteFile)), checksum);
 			SiteModel siteModel = siteParser.parse(input);
 			String checksumString = Long.toString(checksum.getValue());
 			result = new UpdateSite(siteModel, location, checksumString);
 			siteCache.put(location.toString(), result);
 			return result;
 		} catch (SAXException e) {
 			String msg = NLS.bind(Messages.ErrorReadingSite, location);
 			throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
 		} catch (IOException e) {
 			String msg = NLS.bind(Messages.ErrorReadingSite, location);
 			throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
 		} finally {
 			try {
 				if (input != null)
 					input.close();
 			} catch (IOException e) {
 				// ignore
 			}
 			if (!PROTOCOL_FILE.equals(location.getScheme()))
 				siteFile.delete();
 		}
 	}

 	/*
 	 * Load and return an update site object from the given location.
 	 */
 	public static synchronized UpdateSite load(URI location, IProgressMonitor monitor) throws ProvisionException {
 		if (location == null)
 			return null;
 		UpdateSite result = (UpdateSite) siteCache.get(location.toString());
 		if (result != null)
 			return result;
 		InputStream input = null;
 		File siteFile = loadSiteFile(location, monitor);
 		try {
 			DefaultSiteParser siteParser = new DefaultSiteParser(location);
 			Checksum checksum = new CRC32();
 			input = new CheckedInputStream(new BufferedInputStream(new FileInputStream(siteFile)), checksum);
 			SiteModel siteModel = siteParser.parse(input);
 			String checksumString = Long.toString(checksum.getValue());
 			result = new UpdateSite(siteModel, getSiteURI(location), checksumString);
 			siteCache.put(location.toString(), result);
 			return result;
 		} catch (SAXException e) {
 			String msg = NLS.bind(Messages.ErrorReadingSite, location);
 			throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
 		} catch (IOException e) {
 			String msg = NLS.bind(Messages.ErrorReadingSite, location);
 			throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
 		} finally {
 			try {
 				if (input != null)
 					input.close();
 			} catch (IOException e) {
 				// ignore
 			}
 			if (!PROTOCOL_FILE.equals(location.getScheme()))
 				siteFile.delete();
 		}
 	}

 	private static File loadSiteFile(URI location, IProgressMonitor monitor) throws ProvisionException {
 		return loadActualSiteFile(location, getSiteURI(location), monitor);
 	}

 	/**
 	 * Returns a local file containing the contents of the update site at the given location.
 	 */
 	private static File loadActualSiteFile(URI location, URI actualLocation, IProgressMonitor monitor) throws ProvisionException {
 		SubMonitor submonitor = SubMonitor.convert(monitor, 1000);
 		try {
 			File siteFile = null;
 			IStatus transferResult = null;
 			boolean deleteSiteFile = false;
 			try {
 				if (PROTOCOL_FILE.equals(actualLocation.getScheme())) {
 					siteFile = URIUtil.toFile(actualLocation);
 					if (siteFile.exists())
 						transferResult = Status.OK_STATUS;
 					else {
 						String msg = NLS.bind(Messages.ErrorReadingSite, location);
 						transferResult = new Status(IStatus.ERROR, Activator.ID, ProvisionException.ARTIFACT_NOT_FOUND, msg, new FileNotFoundException(siteFile.getAbsolutePath()));
 					}
 				} else {
 					// creating a temp file. In the event of an error we want to delete it.
 					deleteSiteFile = true;
 					OutputStream destination = null;
 					try {
 						siteFile = File.createTempFile("site", ".xml"); //$NON-NLS-1$//$NON-NLS-2$
 						destination = new BufferedOutputStream(new FileOutputStream(siteFile));
 					} catch (IOException e) {
 						throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.INTERNAL_ERROR, "Can not create tempfile for site.xml", e)); //$NON-NLS-1$
 					}
 					try {
 						transferResult = getTransport().download(actualLocation, destination, submonitor.newChild(999));
 					} finally {
 						try {
 							destination.close();
 						} catch (IOException e) {
 							throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.INTERNAL_ERROR, "Failing to close tempfile for site.xml", e)); //$NON-NLS-1$
 						}
 					}
 				}
 				if (monitor.isCanceled())
 					throw new OperationCanceledException();
 				if (transferResult.isOK()) {
 					// successful. If the siteFile is the download of a remote site.xml it will get cleaned up later
 					deleteSiteFile = false;
 					return siteFile;
 				}

 				// The transferStatus from download has a well formatted message that should
 				// be used as it contains useful feedback to the user.
 				// The only thing needed is to translate the error code ARTIFACT_NOT_FOUND to
 				// REPOSITORY_NOT_FOUND as the download does not know what the file represents.
 				//
 				IStatus ms = null;
 				if (transferResult.getException() instanceof FileNotFoundException)
 					ms = new MultiStatus(Activator.ID, //
 							ProvisionException.REPOSITORY_NOT_FOUND,
 							// (code == ProvisionException.ARTIFACT_NOT_FOUND || code == ProvisionException.REPOSITORY_NOT_FOUND ? ProvisionException.REPOSITORY_NOT_FOUND : ProvisionException.REPOSITORY_FAILED_READ), //
 							new IStatus[] {transferResult}, //
 							NLS.bind(Messages.ErrorReadingSite, location), null);
 				else
 					ms = transferResult;
 				throw new ProvisionException(ms);

 			} finally {
 				if (deleteSiteFile && siteFile != null)
 					siteFile.delete();
 			}
 		} finally {
 			if (monitor != null)
 				monitor.done();
 		}
 	}

 	/*
 	 * Parse the feature.xml specified by the given input stream and return the feature object.
 	 * In case of failure, the failure is logged and null is returned
 	 */
 	private static Feature parseFeature(FeatureParser featureParser, URI featureURI, IProgressMonitor monitor) {
 		File featureFile = null;
 		if (PROTOCOL_FILE.equals(featureURI.getScheme())) {
 			featureFile = URIUtil.toFile(featureURI);
 			return featureParser.parse(featureFile);
 		}
 		try {
 			featureFile = File.createTempFile(FEATURE_TEMP_FILE, JAR_EXTENSION);
 			IStatus transferResult = null;
 			//try the download twice in case of transient network problems
 			for (int i = 0; i < RETRY_COUNT; i++) {
 				if (monitor.isCanceled())
 					throw new OperationCanceledException();
 				OutputStream destination = new BufferedOutputStream(new FileOutputStream(featureFile));
 				try {
 					transferResult = getTransport().download(featureURI, destination, monitor);
 				} finally {
 					try {
 						destination.close();
 					} catch (IOException e) {
 						LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI), e));
 						return null;
 					}
 				}
 				if (transferResult.isOK())
 					break;
 			}
 			if (monitor.isCanceled())
 				throw new OperationCanceledException();
 			if (!transferResult.isOK()) {
 				LogHelper.log(new ProvisionException(transferResult));
 				return null;
 			}
 			return featureParser.parse(featureFile);
 		} catch (IOException e) {
 			LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI), e));
 		} finally {
 			if (featureFile != null)
 				featureFile.delete();
 		}
 		return null;
 	}

 	/**
 	 * Throw an exception if the site pointed to by the given URI is not valid.
 	 * @param url the site file to check
 	 * @param monitor a monitor
 	 * @throws UserCancelledException if user canceled during authentication
 	 * @throws AuthenticationFailedException if too many attempts made to login
 	 * @throws FileNotFoundException if the remote file does not exist
 	 * @throws CoreException on errors in communication (unknown host, connection refused, etc.)
 	 */
 	public static void validate(URI url, IProgressMonitor monitor) throws UserCancelledException, AuthenticationFailedException, FileNotFoundException, CoreException {
 		URI siteURI = getSiteURI(url);
 		long lastModified = getTransport().getLastModified(siteURI, monitor);
 		if (lastModified == 0) {
 			throw new FileNotFoundException(url.toString());
 			//			String msg = NLS.bind(Messages.ErrorReadingSite, url);
 			//			throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, null));
 		}
 	}

 	/*
 	 * Constructor for the class.
 	 */
 	private UpdateSite(SiteModel site, URI location, String checksum) {
 		super();
 		this.site = site;
 		this.location = location;
 		this.checksum = checksum;
 		this.rootLocation = getRootLocation();

 	}

 	private URI getRootLocation() {
 		String locationString = location.toString();
 		int slashIndex = locationString.lastIndexOf('/');
 		if (slashIndex == -1 || slashIndex == (locationString.length() - 1))
 			return location;

 		return URI.create(locationString.substring(0, slashIndex + 1));
 	}

 	/*
 	 * Iterate over the archive entries in this site and return the matching URI string for
 	 * the given identifier, if there is one.
 	 */
 	private URI getArchiveURI(URI base, String identifier) {
 		URLEntry[] archives = site.getArchives();
 		for (int i = 0; archives != null && i < archives.length; i++) {
 			URLEntry entry = archives[i];
 			if (identifier.equals(entry.getAnnotation()))
 				return internalGetURI(base, entry.getURL());
 		}
 		return null;
 	}

 	/*
 	 * Return the checksum for this site.
 	 */
 	public String getChecksum() {
 		return checksum;
 	}

 	/*
 	 * Return a URI which represents the location of the given feature.
 	 */
 	public URI getSiteFeatureURI(SiteFeature siteFeature) {
 		URL url = siteFeature.getURL();
 		try {
 			if (url != null)
 				return URIUtil.toURI(url);
 		} catch (URISyntaxException e) {
 			//fall through and resolve the URI ourselves
 		}
 		URI base = getBaseURI();
 		String featureURIString = siteFeature.getURLString();
 		return internalGetURI(base, featureURIString);
 	}

 	/*
 	 * Return a URI which represents the location of the given feature.
 	 */
 	public URI getFeatureURI(String id, String version) {
 		SiteFeature[] entries = site.getFeatures();
 		for (int i = 0; i < entries.length; i++) {
 			if (id.equals(entries[i].getFeatureIdentifier()) && version.equals(entries[i].getFeatureVersion())) {
 				return getSiteFeatureURI(entries[i]);
 			}
 		}

 		URI base = getBaseURI();
 		URI url = getArchiveURI(base, FEATURE_DIR + id + VERSION_SEPARATOR + version + JAR_EXTENSION);
 		if (url != null)
 			return url;
 		return URIUtil.append(base, FEATURE_DIR + id + VERSION_SEPARATOR + version + JAR_EXTENSION);
 	}

 	/*
 	 * Return the location of this site.
 	 */
 	public URI getLocation() {
 		return location;
 	}

 	public String getMirrorsURI() {
 		//copy mirror information from update site to p2 repositories
 		String mirrors = site.getMirrorsURI();
 		if (mirrors == null)
 			return null;
 		//remove site.xml file reference
 		int index = mirrors.indexOf("site.xml"); //$NON-NLS-1$
 		if (index != -1)
 			mirrors = mirrors.substring(0, index) + mirrors.substring(index + "site.xml".length()); //$NON-NLS-1$
 		return mirrors;
 	}

 	/*
 	 * Return a URI which represents the location of the given plug-in.
 	 */
 	public URI getPluginURI(FeatureEntry plugin) {
 		URI base = getBaseURI();
 		String path = PLUGIN_DIR + plugin.getId() + VERSION_SEPARATOR + plugin.getVersion() + JAR_EXTENSION;
 		URI url = getArchiveURI(base, path);
 		if (url != null)
 			return url;
 		return URIUtil.append(base, path);
 	}

 	private URI getBaseURI() {
 		URI base = null;
 		String siteURIString = site.getLocationURIString();
 		if (siteURIString != null) {
 			if (!siteURIString.endsWith("/")) //$NON-NLS-1$
 				siteURIString += "/"; //$NON-NLS-1$
 			base = internalGetURI(rootLocation, siteURIString);
 		}
 		if (base == null)
 			base = rootLocation;
 		return base;
 	}

 	/*
 	 * Return the site model.
 	 */
 	public SiteModel getSite() {
 		return site;
 	}

 	/*
 	 * The trailing parameter can be either null, relative or absolute. If it is null,
 	 * then return null. If it is absolute, then create a new url and return it. If it is
 	 * relative, then make it relative to the given base url.
 	 */
 	private URI internalGetURI(URI base, String trailing) {
 		if (trailing == null)
 			return null;
 		return URIUtil.makeAbsolute(URI.create(trailing), base);
 	}

 	/*
 	 * Load and return the features references in this update site.
 	 */
 	public synchronized Feature[] loadFeatures(IProgressMonitor monitor) throws ProvisionException {
 		if (!featureCache.isEmpty())
 			return (Feature[]) featureCache.values().toArray(new Feature[featureCache.size()]);
 		Feature[] result = loadFeaturesFromDigest(monitor);
 		return result == null ? loadFeaturesFromSite(monitor) : result;
 	}

 	/*
 	 * Try and load the feature information from the update site's
 	 * digest file, if it exists.
 	 */
 	private Feature[] loadFeaturesFromDigest(IProgressMonitor monitor) {
 		File digestFile = null;
 		boolean local = false;
 		try {
 			URI digestURI = getDigestURI();
 			if (PROTOCOL_FILE.equals(digestURI.getScheme())) {
 				digestFile = URIUtil.toFile(digestURI);
 				if (!digestFile.exists())
 					return null;
 				local = true;
 			} else {
 				digestFile = File.createTempFile("digest", ".zip"); //$NON-NLS-1$ //$NON-NLS-2$
 				BufferedOutputStream destination = new BufferedOutputStream(new FileOutputStream(digestFile));
 				IStatus result = null;
 				try {
 					result = getTransport().download(digestURI, destination, monitor);
 				} finally {
 					try {
 						destination.close();
 					} catch (IOException e) {
 						LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, location), e));
 						return null;
 					}
 				}
 				if (result.getSeverity() == IStatus.CANCEL || monitor.isCanceled())
 					throw new OperationCanceledException();
 				if (!result.isOK())
 					return null;
 			}
 			Feature[] features = new DigestParser().parse(digestFile, digestURI);
 			if (features == null)
 				return null;
 			Map tmpFeatureCache = new HashMap(features.length);
 			for (int i = 0; i < features.length; i++) {
 				String key = features[i].getId() + VERSION_SEPARATOR + features[i].getVersion();
 				tmpFeatureCache.put(key, features[i]);
 			}
 			featureCache = tmpFeatureCache;
 			return features;
 		} catch (FileNotFoundException fnfe) {
 			// we do not track FNF exceptions as we will fall back to the
 			// standard feature parsing from the site itself, see bug 225587.
 		} catch (IOException e) {
 			LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingDigest, location), e));
 		} finally {
 			if (!local && digestFile != null)
 				digestFile.delete();
 		}
 		return null;
 	}

 	private URI getDigestURI() {
 		URI digestBase = null;
 		String digestURIString = site.getDigestURIString();
 		if (digestURIString != null) {
 			if (!digestURIString.endsWith("/")) //$NON-NLS-1$
 				digestURIString += "/"; //$NON-NLS-1$
 			digestBase = internalGetURI(rootLocation, digestURIString);
 		}

 		if (digestBase == null)
 			digestBase = rootLocation;

 		return URIUtil.append(digestBase, "digest.zip"); //$NON-NLS-1$
 	}

 	/*
 	 * Load and return the features that are referenced by this update site. Note this
 	 * requires downloading and parsing the feature manifest locally.
 	 */
 	private Feature[] loadFeaturesFromSite(IProgressMonitor monitor) throws ProvisionException {
 		SiteFeature[] siteFeatures = site.getFeatures();
 		FeatureParser featureParser = new FeatureParser();
 		Map tmpFeatureCache = new HashMap(siteFeatures.length);

 		for (int i = 0; i < siteFeatures.length; i++) {
 			if (monitor.isCanceled()) {
 				throw new OperationCanceledException();
 			}
 			SiteFeature siteFeature = siteFeatures[i];
 			String key = null;
 			if (siteFeature.getFeatureIdentifier() != null && siteFeature.getFeatureVersion() != null) {
 				key = siteFeature.getFeatureIdentifier() + VERSION_SEPARATOR + siteFeature.getFeatureVersion();
 				if (tmpFeatureCache.containsKey(key))
 					continue;
 			}
 			URI featureURI = getSiteFeatureURI(siteFeature);
 			Feature feature = parseFeature(featureParser, featureURI, new NullProgressMonitor());
 			if (feature == null) {
 				LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI)));
 			} else {
 				if (key == null) {
 					siteFeature.setFeatureIdentifier(feature.getId());
 					siteFeature.setFeatureVersion(feature.getVersion());
 					key = siteFeature.getFeatureIdentifier() + VERSION_SEPARATOR + siteFeature.getFeatureVersion();
 				}
 				tmpFeatureCache.put(key, feature);
 				loadIncludedFeatures(feature, featureParser, tmpFeatureCache, monitor);
 			}
 		}
 		featureCache = tmpFeatureCache;
 		return (Feature[]) featureCache.values().toArray(new Feature[featureCache.size()]);
 	}

 	/*
 	 * Load the features that are included by the given feature.
 	 */
 	private void loadIncludedFeatures(Feature feature, FeatureParser featureParser, Map features, IProgressMonitor monitor) throws ProvisionException {
 		FeatureEntry[] featureEntries = feature.getEntries();
 		for (int i = 0; i < featureEntries.length; i++) {
 			if (monitor.isCanceled())
 				throw new OperationCanceledException();
 			FeatureEntry entry = featureEntries[i];
 			if (entry.isRequires() || entry.isPlugin())
 				continue;
 			String key = entry.getId() + VERSION_SEPARATOR + entry.getVersion();
 			if (features.containsKey(key))
 				continue;

 			URI includedFeatureURI = getFeatureURI(entry.getId(), entry.getVersion());
 			Feature includedFeature = parseFeature(featureParser, includedFeatureURI, monitor);
 			if (includedFeature == null) {
 				LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, includedFeatureURI)));
 			} else {
 				features.put(key, includedFeature);
 				loadIncludedFeatures(includedFeature, featureParser, features, monitor);
 			}
 		}
 	}

 	private static RepositoryTransport getTransport() {
 		return RepositoryTransport.getInstance();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2008, 2009 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.equinox.internal.p2.updatesite;

	import java.io.*;
	import java.net.*;
	import java.util.HashMap;
	import java.util.Map;
	import java.util.zip.*;
	import org.eclipse.core.runtime.*;
	import org.eclipse.ecf.filetransfer.UserCancelledException;
	import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
	import org.eclipse.equinox.internal.p2.publisher.eclipse.FeatureParser;
	import org.eclipse.equinox.internal.p2.repository.AuthenticationFailedException;
	import org.eclipse.equinox.internal.p2.repository.RepositoryTransport;
	import org.eclipse.equinox.internal.provisional.p2.core.ProvisionException;
	import org.eclipse.equinox.p2.publisher.eclipse.*;
	import org.eclipse.osgi.util.NLS;
	import org.xml.sax.SAXException;

	/**
	* @since 1.0
	*/
	public class UpdateSite {

	private static final String VERSION_SEPARATOR = "_"; //$NON-NLS-1$
	private static final String JAR_EXTENSION = ".jar"; //$NON-NLS-1$
	private static final String FEATURE_DIR = "features/"; //$NON-NLS-1$
	private static final String PLUGIN_DIR = "plugins/"; //$NON-NLS-1$
	private static final String FEATURE_TEMP_FILE = "feature"; //$NON-NLS-1$
	private static final String SITE_FILE = "site.xml"; //$NON-NLS-1$
	private static final String PROTOCOL_FILE = "file"; //$NON-NLS-1$
	private static final int RETRY_COUNT = 2;
	private static final String DOT_XML = ".xml"; //$NON-NLS-1$
	private static final String SITE = "site"; //$NON-NLS-1$
	private String checksum;
	private URI location;
	private URI rootLocation;
	private SiteModel site;

	/*
	* Some variables for caching.
	*/
	// map of String (URI.toString()) to UpdateSite
	private static Map siteCache = new HashMap();
	// map of String (featureID_featureVersion) to Feature
	private Map featureCache = new HashMap();

	/*
	* Return a URI based on the given URI, which points to a site.xml file.
	*/
	private static URI getSiteURI(URI baseLocation) {
	String segment = URIUtil.lastSegment(baseLocation);
	if (constainsUpdateSiteFileName(segment))
	return baseLocation;
	return URIUtil.append(baseLocation, SITE_FILE);
	}

	/**
	* Be lenient about accepting any location with site.xml at the end.
	*/
	private static boolean constainsUpdateSiteFileName(String segment) {
	return segment != null && segment.endsWith(DOT_XML) && segment.indexOf(SITE) != -1;
	}

	/**
	* Loads and returns a category file
	* @param location
	* @param monitor
	* @return A CategoryFile
	* @throws ProvisionException
	*/
	public static synchronized UpdateSite loadCategoryFile(URI location, IProgressMonitor monitor) throws ProvisionException {
	if (location == null)
	return null;
	UpdateSite result = (UpdateSite) siteCache.get(location.toString());
	if (result != null)
	return result;
	InputStream input = null;
	File siteFile = loadActualSiteFile(location, location, monitor);
	try {
	DefaultSiteParser siteParser = new DefaultSiteParser(location);
	Checksum checksum = new CRC32();
	input = new CheckedInputStream(new BufferedInputStream(new FileInputStream(siteFile)), checksum);
	SiteModel siteModel = siteParser.parse(input);
	String checksumString = Long.toString(checksum.getValue());
	result = new UpdateSite(siteModel, location, checksumString);
	siteCache.put(location.toString(), result);
	return result;
	} catch (SAXException e) {
	String msg = NLS.bind(Messages.ErrorReadingSite, location);
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
	} catch (IOException e) {
	String msg = NLS.bind(Messages.ErrorReadingSite, location);
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
	} finally {
	try {
	if (input != null)
	input.close();
	} catch (IOException e) {
	// ignore
	}
	if (!PROTOCOL_FILE.equals(location.getScheme()))
	siteFile.delete();
	}
	}

	/*
	* Load and return an update site object from the given location.
	*/
	public static synchronized UpdateSite load(URI location, IProgressMonitor monitor) throws ProvisionException {
	if (location == null)
	return null;
	UpdateSite result = (UpdateSite) siteCache.get(location.toString());
	if (result != null)
	return result;
	InputStream input = null;
	File siteFile = loadSiteFile(location, monitor);
	try {
	DefaultSiteParser siteParser = new DefaultSiteParser(location);
	Checksum checksum = new CRC32();
	input = new CheckedInputStream(new BufferedInputStream(new FileInputStream(siteFile)), checksum);
	SiteModel siteModel = siteParser.parse(input);
	String checksumString = Long.toString(checksum.getValue());
	result = new UpdateSite(siteModel, getSiteURI(location), checksumString);
	siteCache.put(location.toString(), result);
	return result;
	} catch (SAXException e) {
	String msg = NLS.bind(Messages.ErrorReadingSite, location);
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
	} catch (IOException e) {
	String msg = NLS.bind(Messages.ErrorReadingSite, location);
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, e));
	} finally {
	try {
	if (input != null)
	input.close();
	} catch (IOException e) {
	// ignore
	}
	if (!PROTOCOL_FILE.equals(location.getScheme()))
	siteFile.delete();
	}
	}

	private static File loadSiteFile(URI location, IProgressMonitor monitor) throws ProvisionException {
	return loadActualSiteFile(location, getSiteURI(location), monitor);
	}

	/**
	* Returns a local file containing the contents of the update site at the given location.
	*/
	private static File loadActualSiteFile(URI location, URI actualLocation, IProgressMonitor monitor) throws ProvisionException {
	SubMonitor submonitor = SubMonitor.convert(monitor, 1000);
	try {
	File siteFile = null;
	IStatus transferResult = null;
	boolean deleteSiteFile = false;
	try {
	if (PROTOCOL_FILE.equals(actualLocation.getScheme())) {
	siteFile = URIUtil.toFile(actualLocation);
	if (siteFile.exists())
	transferResult = Status.OK_STATUS;
	else {
	String msg = NLS.bind(Messages.ErrorReadingSite, location);
	transferResult = new Status(IStatus.ERROR, Activator.ID, ProvisionException.ARTIFACT_NOT_FOUND, msg, new FileNotFoundException(siteFile.getAbsolutePath()));
	}
	} else {
	// creating a temp file. In the event of an error we want to delete it.
	deleteSiteFile = true;
	OutputStream destination = null;
	try {
	siteFile = File.createTempFile("site", ".xml"); //$NON-NLS-1$//$NON-NLS-2$
	destination = new BufferedOutputStream(new FileOutputStream(siteFile));
	} catch (IOException e) {
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.INTERNAL_ERROR, "Can not create tempfile for site.xml", e)); //$NON-NLS-1$
	}
	try {
	transferResult = getTransport().download(actualLocation, destination, submonitor.newChild(999));
	} finally {
	try {
	destination.close();
	} catch (IOException e) {
	throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.INTERNAL_ERROR, "Failing to close tempfile for site.xml", e)); //$NON-NLS-1$
	}
	}
	}
	if (monitor.isCanceled())
	throw new OperationCanceledException();
	if (transferResult.isOK()) {
	// successful. If the siteFile is the download of a remote site.xml it will get cleaned up later
	deleteSiteFile = false;
	return siteFile;
	}

	// The transferStatus from download has a well formatted message that should
	// be used as it contains useful feedback to the user.
	// The only thing needed is to translate the error code ARTIFACT_NOT_FOUND to
	// REPOSITORY_NOT_FOUND as the download does not know what the file represents.
	//
	IStatus ms = null;
	if (transferResult.getException() instanceof FileNotFoundException)
	ms = new MultiStatus(Activator.ID, //
	ProvisionException.REPOSITORY_NOT_FOUND,
	// (code == ProvisionException.ARTIFACT_NOT_FOUND \|\| code == ProvisionException.REPOSITORY_NOT_FOUND ? ProvisionException.REPOSITORY_NOT_FOUND : ProvisionException.REPOSITORY_FAILED_READ), //
	new IStatus[] {transferResult}, //
	NLS.bind(Messages.ErrorReadingSite, location), null);
	else
	ms = transferResult;
	throw new ProvisionException(ms);

	} finally {
	if (deleteSiteFile && siteFile != null)
	siteFile.delete();
	}
	} finally {
	if (monitor != null)
	monitor.done();
	}
	}

	/*
	* Parse the feature.xml specified by the given input stream and return the feature object.
	* In case of failure, the failure is logged and null is returned
	*/
	private static Feature parseFeature(FeatureParser featureParser, URI featureURI, IProgressMonitor monitor) {
	File featureFile = null;
	if (PROTOCOL_FILE.equals(featureURI.getScheme())) {
	featureFile = URIUtil.toFile(featureURI);
	return featureParser.parse(featureFile);
	}
	try {
	featureFile = File.createTempFile(FEATURE_TEMP_FILE, JAR_EXTENSION);
	IStatus transferResult = null;
	//try the download twice in case of transient network problems
	for (int i = 0; i < RETRY_COUNT; i++) {
	if (monitor.isCanceled())
	throw new OperationCanceledException();
	OutputStream destination = new BufferedOutputStream(new FileOutputStream(featureFile));
	try {
	transferResult = getTransport().download(featureURI, destination, monitor);
	} finally {
	try {
	destination.close();
	} catch (IOException e) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI), e));
	return null;
	}
	}
	if (transferResult.isOK())
	break;
	}
	if (monitor.isCanceled())
	throw new OperationCanceledException();
	if (!transferResult.isOK()) {
	LogHelper.log(new ProvisionException(transferResult));
	return null;
	}
	return featureParser.parse(featureFile);
	} catch (IOException e) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI), e));
	} finally {
	if (featureFile != null)
	featureFile.delete();
	}
	return null;
	}

	/**
	* Throw an exception if the site pointed to by the given URI is not valid.
	* @param url the site file to check
	* @param monitor a monitor
	* @throws UserCancelledException if user canceled during authentication
	* @throws AuthenticationFailedException if too many attempts made to login
	* @throws FileNotFoundException if the remote file does not exist
	* @throws CoreException on errors in communication (unknown host, connection refused, etc.)
	*/
	public static void validate(URI url, IProgressMonitor monitor) throws UserCancelledException, AuthenticationFailedException, FileNotFoundException, CoreException {
	URI siteURI = getSiteURI(url);
	long lastModified = getTransport().getLastModified(siteURI, monitor);
	if (lastModified == 0) {
	throw new FileNotFoundException(url.toString());
	// String msg = NLS.bind(Messages.ErrorReadingSite, url);
	// throw new ProvisionException(new Status(IStatus.ERROR, Activator.ID, ProvisionException.REPOSITORY_FAILED_READ, msg, null));
	}
	}

	/*
	* Constructor for the class.
	*/
	private UpdateSite(SiteModel site, URI location, String checksum) {
	super();
	this.site = site;
	this.location = location;
	this.checksum = checksum;
	this.rootLocation = getRootLocation();

	}

	private URI getRootLocation() {
	String locationString = location.toString();
	int slashIndex = locationString.lastIndexOf('/');
	if (slashIndex == -1 \|\| slashIndex == (locationString.length() - 1))
	return location;

	return URI.create(locationString.substring(0, slashIndex + 1));
	}

	/*
	* Iterate over the archive entries in this site and return the matching URI string for
	* the given identifier, if there is one.
	*/
	private URI getArchiveURI(URI base, String identifier) {
	URLEntry[] archives = site.getArchives();
	for (int i = 0; archives != null && i < archives.length; i++) {
	URLEntry entry = archives[i];
	if (identifier.equals(entry.getAnnotation()))
	return internalGetURI(base, entry.getURL());
	}
	return null;
	}

	/*
	* Return the checksum for this site.
	*/
	public String getChecksum() {
	return checksum;
	}

	/*
	* Return a URI which represents the location of the given feature.
	*/
	public URI getSiteFeatureURI(SiteFeature siteFeature) {
	URL url = siteFeature.getURL();
	try {
	if (url != null)
	return URIUtil.toURI(url);
	} catch (URISyntaxException e) {
	//fall through and resolve the URI ourselves
	}
	URI base = getBaseURI();
	String featureURIString = siteFeature.getURLString();
	return internalGetURI(base, featureURIString);
	}

	/*
	* Return a URI which represents the location of the given feature.
	*/
	public URI getFeatureURI(String id, String version) {
	SiteFeature[] entries = site.getFeatures();
	for (int i = 0; i < entries.length; i++) {
	if (id.equals(entries[i].getFeatureIdentifier()) && version.equals(entries[i].getFeatureVersion())) {
	return getSiteFeatureURI(entries[i]);
	}
	}

	URI base = getBaseURI();
	URI url = getArchiveURI(base, FEATURE_DIR + id + VERSION_SEPARATOR + version + JAR_EXTENSION);
	if (url != null)
	return url;
	return URIUtil.append(base, FEATURE_DIR + id + VERSION_SEPARATOR + version + JAR_EXTENSION);
	}

	/*
	* Return the location of this site.
	*/
	public URI getLocation() {
	return location;
	}

	public String getMirrorsURI() {
	//copy mirror information from update site to p2 repositories
	String mirrors = site.getMirrorsURI();
	if (mirrors == null)
	return null;
	//remove site.xml file reference
	int index = mirrors.indexOf("site.xml"); //$NON-NLS-1$
	if (index != -1)
	mirrors = mirrors.substring(0, index) + mirrors.substring(index + "site.xml".length()); //$NON-NLS-1$
	return mirrors;
	}

	/*
	* Return a URI which represents the location of the given plug-in.
	*/
	public URI getPluginURI(FeatureEntry plugin) {
	URI base = getBaseURI();
	String path = PLUGIN_DIR + plugin.getId() + VERSION_SEPARATOR + plugin.getVersion() + JAR_EXTENSION;
	URI url = getArchiveURI(base, path);
	if (url != null)
	return url;
	return URIUtil.append(base, path);
	}

	private URI getBaseURI() {
	URI base = null;
	String siteURIString = site.getLocationURIString();
	if (siteURIString != null) {
	if (!siteURIString.endsWith("/")) //$NON-NLS-1$
	siteURIString += "/"; //$NON-NLS-1$
	base = internalGetURI(rootLocation, siteURIString);
	}
	if (base == null)
	base = rootLocation;
	return base;
	}

	/*
	* Return the site model.
	*/
	public SiteModel getSite() {
	return site;
	}

	/*
	* The trailing parameter can be either null, relative or absolute. If it is null,
	* then return null. If it is absolute, then create a new url and return it. If it is
	* relative, then make it relative to the given base url.
	*/
	private URI internalGetURI(URI base, String trailing) {
	if (trailing == null)
	return null;
	return URIUtil.makeAbsolute(URI.create(trailing), base);
	}

	/*
	* Load and return the features references in this update site.
	*/
	public synchronized Feature[] loadFeatures(IProgressMonitor monitor) throws ProvisionException {
	if (!featureCache.isEmpty())
	return (Feature[]) featureCache.values().toArray(new Feature[featureCache.size()]);
	Feature[] result = loadFeaturesFromDigest(monitor);
	return result == null ? loadFeaturesFromSite(monitor) : result;
	}

	/*
	* Try and load the feature information from the update site's
	* digest file, if it exists.
	*/
	private Feature[] loadFeaturesFromDigest(IProgressMonitor monitor) {
	File digestFile = null;
	boolean local = false;
	try {
	URI digestURI = getDigestURI();
	if (PROTOCOL_FILE.equals(digestURI.getScheme())) {
	digestFile = URIUtil.toFile(digestURI);
	if (!digestFile.exists())
	return null;
	local = true;
	} else {
	digestFile = File.createTempFile("digest", ".zip"); //$NON-NLS-1$ //$NON-NLS-2$
	BufferedOutputStream destination = new BufferedOutputStream(new FileOutputStream(digestFile));
	IStatus result = null;
	try {
	result = getTransport().download(digestURI, destination, monitor);
	} finally {
	try {
	destination.close();
	} catch (IOException e) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, location), e));
	return null;
	}
	}
	if (result.getSeverity() == IStatus.CANCEL \|\| monitor.isCanceled())
	throw new OperationCanceledException();
	if (!result.isOK())
	return null;
	}
	Feature[] features = new DigestParser().parse(digestFile, digestURI);
	if (features == null)
	return null;
	Map tmpFeatureCache = new HashMap(features.length);
	for (int i = 0; i < features.length; i++) {
	String key = features[i].getId() + VERSION_SEPARATOR + features[i].getVersion();
	tmpFeatureCache.put(key, features[i]);
	}
	featureCache = tmpFeatureCache;
	return features;
	} catch (FileNotFoundException fnfe) {
	// we do not track FNF exceptions as we will fall back to the
	// standard feature parsing from the site itself, see bug 225587.
	} catch (IOException e) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingDigest, location), e));
	} finally {
	if (!local && digestFile != null)
	digestFile.delete();
	}
	return null;
	}

	private URI getDigestURI() {
	URI digestBase = null;
	String digestURIString = site.getDigestURIString();
	if (digestURIString != null) {
	if (!digestURIString.endsWith("/")) //$NON-NLS-1$
	digestURIString += "/"; //$NON-NLS-1$
	digestBase = internalGetURI(rootLocation, digestURIString);
	}

	if (digestBase == null)
	digestBase = rootLocation;

	return URIUtil.append(digestBase, "digest.zip"); //$NON-NLS-1$
	}

	/*
	* Load and return the features that are referenced by this update site. Note this
	* requires downloading and parsing the feature manifest locally.
	*/
	private Feature[] loadFeaturesFromSite(IProgressMonitor monitor) throws ProvisionException {
	SiteFeature[] siteFeatures = site.getFeatures();
	FeatureParser featureParser = new FeatureParser();
	Map tmpFeatureCache = new HashMap(siteFeatures.length);

	for (int i = 0; i < siteFeatures.length; i++) {
	if (monitor.isCanceled()) {
	throw new OperationCanceledException();
	}
	SiteFeature siteFeature = siteFeatures[i];
	String key = null;
	if (siteFeature.getFeatureIdentifier() != null && siteFeature.getFeatureVersion() != null) {
	key = siteFeature.getFeatureIdentifier() + VERSION_SEPARATOR + siteFeature.getFeatureVersion();
	if (tmpFeatureCache.containsKey(key))
	continue;
	}
	URI featureURI = getSiteFeatureURI(siteFeature);
	Feature feature = parseFeature(featureParser, featureURI, new NullProgressMonitor());
	if (feature == null) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, featureURI)));
	} else {
	if (key == null) {
	siteFeature.setFeatureIdentifier(feature.getId());
	siteFeature.setFeatureVersion(feature.getVersion());
	key = siteFeature.getFeatureIdentifier() + VERSION_SEPARATOR + siteFeature.getFeatureVersion();
	}
	tmpFeatureCache.put(key, feature);
	loadIncludedFeatures(feature, featureParser, tmpFeatureCache, monitor);
	}
	}
	featureCache = tmpFeatureCache;
	return (Feature[]) featureCache.values().toArray(new Feature[featureCache.size()]);
	}

	/*
	* Load the features that are included by the given feature.
	*/
	private void loadIncludedFeatures(Feature feature, FeatureParser featureParser, Map features, IProgressMonitor monitor) throws ProvisionException {
	FeatureEntry[] featureEntries = feature.getEntries();
	for (int i = 0; i < featureEntries.length; i++) {
	if (monitor.isCanceled())
	throw new OperationCanceledException();
	FeatureEntry entry = featureEntries[i];
	if (entry.isRequires() \|\| entry.isPlugin())
	continue;
	String key = entry.getId() + VERSION_SEPARATOR + entry.getVersion();
	if (features.containsKey(key))
	continue;

	URI includedFeatureURI = getFeatureURI(entry.getId(), entry.getVersion());
	Feature includedFeature = parseFeature(featureParser, includedFeatureURI, monitor);
	if (includedFeature == null) {
	LogHelper.log(new Status(IStatus.ERROR, Activator.ID, NLS.bind(Messages.ErrorReadingFeature, includedFeatureURI)));
	} else {
	features.put(key, includedFeature);
	loadIncludedFeatures(includedFeature, featureParser, features, monitor);
	}
	}
	}

	private static RepositoryTransport getTransport() {
	return RepositoryTransport.getInstance();
	}
	}