org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportAmazonS3.java - sop/jgit - Git at Google

 /*
  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
  * under the terms of the Eclipse Distribution License v1.0 which
  * accompanies this distribution, is reproduced below, and is
  * available at http://www.eclipse.org/org/documents/edl-v10.php
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
  *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  *
  * - Redistributions in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials provided
  *   with the distribution.
  *
  * - Neither the name of the Eclipse Foundation, Inc. nor the
  *   names of its contributors may be used to endorse or promote
  *   products derived from this software without specific prior
  *   written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 package org.eclipse.jgit.transport;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.URLConnection;
 import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 import java.util.TreeMap;

 import org.eclipse.jgit.errors.NotSupportedException;
 import org.eclipse.jgit.errors.TransportException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectIdRef;
 import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Ref.Storage;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.SymbolicRef;

 /**
  * Transport over the non-Git aware Amazon S3 protocol.
  * <p>
  * This transport communicates with the Amazon S3 servers (a non-free commercial
  * hosting service that users must subscribe to). Some users may find transport
  * to and from S3 to be a useful backup service.
  * <p>
  * The transport does not require any specialized Git support on the remote
  * (server side) repository, as Amazon does not provide any such support.
  * Repository files are retrieved directly through the S3 API, which uses
  * extended HTTP/1.1 semantics. This make it possible to read or write Git data
  * from a remote repository that is stored on S3.
  * <p>
  * Unlike the HTTP variant (see {@link TransportHttp}) we rely upon being able
  * to list objects in a bucket, as the S3 API supports this function. By listing
  * the bucket contents we can avoid relying on <code>objects/info/packs</code>
  * or <code>info/refs</code> in the remote repository.
  * <p>
  * Concurrent pushing over this transport is not supported. Multiple concurrent
  * push operations may cause confusion in the repository state.
  *
  * @see WalkFetchConnection
  * @see WalkPushConnection
  */
 public class TransportAmazonS3 extends HttpTransport implements WalkTransport {
 	static final String S3_SCHEME = "amazon-s3"; //$NON-NLS-1$

 	static final TransportProtocol PROTO_S3 = new TransportProtocol() {
 		@Override
 		public String getName() {
 			return "Amazon S3"; //$NON-NLS-1$
 		}

 		@Override
 		public Set<String> getSchemes() {
 			return Collections.singleton(S3_SCHEME);
 		}

 		@Override
 		public Set<URIishField> getRequiredFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.USER,
 					URIishField.HOST, URIishField.PATH));
 		}

 		@Override
 		public Set<URIishField> getOptionalFields() {
 			return Collections.unmodifiableSet(EnumSet.of(URIishField.PASS));
 		}

 		@Override
 		public Transport open(URIish uri, Repository local, String remoteName)
 				throws NotSupportedException {
 			return new TransportAmazonS3(local, uri);
 		}
 	};

 	/** User information necessary to connect to S3. */
 	final AmazonS3 s3;

 	/** Bucket the remote repository is stored in. */
 	final String bucket;

 	/**
 	 * Key prefix which all objects related to the repository start with.
 	 * <p>
 	 * The prefix does not start with "/".
 	 * <p>
 	 * The prefix does not end with "/". The trailing slash is stripped during
 	 * the constructor if a trailing slash was supplied in the URIish.
 	 * <p>
 	 * All files within the remote repository start with
 	 * <code>keyPrefix + "/"</code>.
 	 */
 	private final String keyPrefix;

 	TransportAmazonS3(final Repository local, final URIish uri)
 			throws NotSupportedException {
 		super(local, uri);

 		Properties props = loadProperties();
 		File directory = local.getDirectory();
 		if (!props.containsKey("tmpdir") && directory != null) //$NON-NLS-1$
 			props.put("tmpdir", directory.getPath()); //$NON-NLS-1$

 		s3 = new AmazonS3(props);
 		bucket = uri.getHost();

 		String p = uri.getPath();
 		if (p.startsWith("/")) //$NON-NLS-1$
 			p = p.substring(1);
 		if (p.endsWith("/")) //$NON-NLS-1$
 			p = p.substring(0, p.length() - 1);
 		keyPrefix = p;
 	}

 	private Properties loadProperties() throws NotSupportedException {
 		if (local.getDirectory() != null) {
 			File propsFile = new File(local.getDirectory(), uri.getUser());
 			if (propsFile.isFile())
 				return loadPropertiesFile(propsFile);
 		}

 		File propsFile = new File(local.getFS().userHome(), uri.getUser());
 		if (propsFile.isFile())
 			return loadPropertiesFile(propsFile);

 		Properties props = new Properties();
 		String user = uri.getUser();
 		String pass = uri.getPass();
 		if (user != null && pass != null) {
 		        props.setProperty("accesskey", user); //$NON-NLS-1$
 		        props.setProperty("secretkey", pass); //$NON-NLS-1$
 		} else
 			throw new NotSupportedException(MessageFormat.format(
 					JGitText.get().cannotReadFile, propsFile));
 		return props;
 	}

 	private static Properties loadPropertiesFile(File propsFile)
 			throws NotSupportedException {
 		try {
 			return AmazonS3.properties(propsFile);
 		} catch (IOException e) {
 			throw new NotSupportedException(MessageFormat.format(
 					JGitText.get().cannotReadFile, propsFile), e);
 		}
 	}

 	@Override
 	public FetchConnection openFetch() throws TransportException {
 		final DatabaseS3 c = new DatabaseS3(bucket, keyPrefix + "/objects"); //$NON-NLS-1$
 		final WalkFetchConnection r = new WalkFetchConnection(this, c);
 		r.available(c.readAdvertisedRefs());
 		return r;
 	}

 	@Override
 	public PushConnection openPush() throws TransportException {
 		final DatabaseS3 c = new DatabaseS3(bucket, keyPrefix + "/objects"); //$NON-NLS-1$
 		final WalkPushConnection r = new WalkPushConnection(this, c);
 		r.available(c.readAdvertisedRefs());
 		return r;
 	}

 	@Override
 	public void close() {
 		// No explicit connections are maintained.
 	}

 	class DatabaseS3 extends WalkRemoteObjectDatabase {
 		private final String bucketName;

 		private final String objectsKey;

 		DatabaseS3(final String b, final String o) {
 			bucketName = b;
 			objectsKey = o;
 		}

 		private String resolveKey(String subpath) {
 			if (subpath.endsWith("/")) //$NON-NLS-1$
 				subpath = subpath.substring(0, subpath.length() - 1);
 			String k = objectsKey;
 			while (subpath.startsWith(ROOT_DIR)) {
 				k = k.substring(0, k.lastIndexOf('/'));
 				subpath = subpath.substring(3);
 			}
 			return k + "/" + subpath; //$NON-NLS-1$
 		}

 		@Override
 		URIish getURI() {
 			URIish u = new URIish();
 			u = u.setScheme(S3_SCHEME);
 			u = u.setHost(bucketName);
 			u = u.setPath("/" + objectsKey); //$NON-NLS-1$
 			return u;
 		}

 		@Override
 		Collection<WalkRemoteObjectDatabase> getAlternates() throws IOException {
 			try {
 				return readAlternates(INFO_ALTERNATES);
 			} catch (FileNotFoundException err) {
 				// Fall through.
 			}
 			return null;
 		}

 		@Override
 		WalkRemoteObjectDatabase openAlternate(final String location)
 				throws IOException {
 			return new DatabaseS3(bucketName, resolveKey(location));
 		}

 		@Override
 		Collection<String> getPackNames() throws IOException {
 			final HashSet<String> have = new HashSet<>();
 			have.addAll(s3.list(bucket, resolveKey("pack"))); //$NON-NLS-1$

 			final Collection<String> packs = new ArrayList<>();
 			for (final String n : have) {
 				if (!n.startsWith("pack-") || !n.endsWith(".pack")) //$NON-NLS-1$ //$NON-NLS-2$
 					continue;

 				final String in = n.substring(0, n.length() - 5) + ".idx"; //$NON-NLS-1$
 				if (have.contains(in))
 					packs.add(n);
 			}
 			return packs;
 		}

 		@Override
 		FileStream open(final String path) throws IOException {
 			final URLConnection c = s3.get(bucket, resolveKey(path));
 			final InputStream raw = c.getInputStream();
 			final InputStream in = s3.decrypt(c);
 			final int len = c.getContentLength();
 			return new FileStream(in, raw == in ? len : -1);
 		}

 		@Override
 		void deleteFile(final String path) throws IOException {
 			s3.delete(bucket, resolveKey(path));
 		}

 		@Override
 		OutputStream writeFile(final String path,
 				final ProgressMonitor monitor, final String monitorTask)
 				throws IOException {
 			return s3.beginPut(bucket, resolveKey(path), monitor, monitorTask);
 		}

 		@Override
 		void writeFile(final String path, final byte[] data) throws IOException {
 			s3.put(bucket, resolveKey(path), data);
 		}

 		Map<String, Ref> readAdvertisedRefs() throws TransportException {
 			final TreeMap<String, Ref> avail = new TreeMap<>();
 			readPackedRefs(avail);
 			readLooseRefs(avail);
 			readRef(avail, Constants.HEAD);
 			return avail;
 		}

 		private void readLooseRefs(final TreeMap<String, Ref> avail)
 				throws TransportException {
 			try {
 				for (final String n : s3.list(bucket, resolveKey(ROOT_DIR
 						+ "refs"))) //$NON-NLS-1$
 					readRef(avail, "refs/" + n); //$NON-NLS-1$
 			} catch (IOException e) {
 				throw new TransportException(getURI(), JGitText.get().cannotListRefs, e);
 			}
 		}

 		private Ref readRef(final TreeMap<String, Ref> avail, final String rn)
 				throws TransportException {
 			final String s;
 			String ref = ROOT_DIR + rn;
 			try {
 				final BufferedReader br = openReader(ref);
 				try {
 					s = br.readLine();
 				} finally {
 					br.close();
 				}
 			} catch (FileNotFoundException noRef) {
 				return null;
 			} catch (IOException err) {
 				throw new TransportException(getURI(), MessageFormat.format(
 						JGitText.get().transportExceptionReadRef, ref), err);
 			}

 			if (s == null)
 				throw new TransportException(getURI(), MessageFormat.format(JGitText.get().transportExceptionEmptyRef, rn));

 			if (s.startsWith("ref: ")) { //$NON-NLS-1$
 				final String target = s.substring("ref: ".length()); //$NON-NLS-1$
 				Ref r = avail.get(target);
 				if (r == null)
 					r = readRef(avail, target);
 				if (r == null)
 					r = new ObjectIdRef.Unpeeled(Ref.Storage.NEW, target, null);
 				r = new SymbolicRef(rn, r);
 				avail.put(r.getName(), r);
 				return r;
 			}

 			if (ObjectId.isId(s)) {
 				final Ref r = new ObjectIdRef.Unpeeled(loose(avail.get(rn)),
 						rn, ObjectId.fromString(s));
 				avail.put(r.getName(), r);
 				return r;
 			}

 			throw new TransportException(getURI(), MessageFormat.format(JGitText.get().transportExceptionBadRef, rn, s));
 		}

 		private Storage loose(final Ref r) {
 			if (r != null && r.getStorage() == Storage.PACKED)
 				return Storage.LOOSE_PACKED;
 			return Storage.LOOSE;
 		}

 		@Override
 		void close() {
 			// We do not maintain persistent connections.
 		}
 	}
 }
	/*
	* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
	* and other copyright owners as documented in the project's IP log.
	*
	* This program and the accompanying materials are made available
	* under the terms of the Eclipse Distribution License v1.0 which
	* accompanies this distribution, is reproduced below, and is
	* available at http://www.eclipse.org/org/documents/edl-v10.php
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or
	* without modification, are permitted provided that the following
	* conditions are met:
	*
	* - Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* - Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials provided
	* with the distribution.
	*
	* - Neither the name of the Eclipse Foundation, Inc. nor the
	* names of its contributors may be used to endorse or promote
	* products derived from this software without specific prior
	* written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
	* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	package org.eclipse.jgit.transport;

	import java.io.BufferedReader;
	import java.io.File;
	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.net.URLConnection;
	import java.text.MessageFormat;
	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.EnumSet;
	import java.util.HashSet;
	import java.util.Map;
	import java.util.Properties;
	import java.util.Set;
	import java.util.TreeMap;

	import org.eclipse.jgit.errors.NotSupportedException;
	import org.eclipse.jgit.errors.TransportException;
	import org.eclipse.jgit.internal.JGitText;
	import org.eclipse.jgit.lib.Constants;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.ObjectIdRef;
	import org.eclipse.jgit.lib.ProgressMonitor;
	import org.eclipse.jgit.lib.Ref;
	import org.eclipse.jgit.lib.Ref.Storage;
	import org.eclipse.jgit.lib.Repository;
	import org.eclipse.jgit.lib.SymbolicRef;

	/**
	* Transport over the non-Git aware Amazon S3 protocol.
	* <p>
	* This transport communicates with the Amazon S3 servers (a non-free commercial
	* hosting service that users must subscribe to). Some users may find transport
	* to and from S3 to be a useful backup service.
	* <p>
	* The transport does not require any specialized Git support on the remote
	* (server side) repository, as Amazon does not provide any such support.
	* Repository files are retrieved directly through the S3 API, which uses
	* extended HTTP/1.1 semantics. This make it possible to read or write Git data
	* from a remote repository that is stored on S3.
	* <p>
	* Unlike the HTTP variant (see {@link TransportHttp}) we rely upon being able
	* to list objects in a bucket, as the S3 API supports this function. By listing
	* the bucket contents we can avoid relying on <code>objects/info/packs</code>
	* or <code>info/refs</code> in the remote repository.
	* <p>
	* Concurrent pushing over this transport is not supported. Multiple concurrent
	* push operations may cause confusion in the repository state.
	*
	* @see WalkFetchConnection
	* @see WalkPushConnection
	*/
	public class TransportAmazonS3 extends HttpTransport implements WalkTransport {
	static final String S3_SCHEME = "amazon-s3"; //$NON-NLS-1$

	static final TransportProtocol PROTO_S3 = new TransportProtocol() {
	@Override
	public String getName() {
	return "Amazon S3"; //$NON-NLS-1$
	}

	@Override
	public Set<String> getSchemes() {
	return Collections.singleton(S3_SCHEME);
	}

	@Override
	public Set<URIishField> getRequiredFields() {
	return Collections.unmodifiableSet(EnumSet.of(URIishField.USER,
	URIishField.HOST, URIishField.PATH));
	}

	@Override
	public Set<URIishField> getOptionalFields() {
	return Collections.unmodifiableSet(EnumSet.of(URIishField.PASS));
	}

	@Override
	public Transport open(URIish uri, Repository local, String remoteName)
	throws NotSupportedException {
	return new TransportAmazonS3(local, uri);
	}
	};

	/** User information necessary to connect to S3. */
	final AmazonS3 s3;

	/** Bucket the remote repository is stored in. */
	final String bucket;

	/**
	* Key prefix which all objects related to the repository start with.
	* <p>
	* The prefix does not start with "/".
	* <p>
	* The prefix does not end with "/". The trailing slash is stripped during
	* the constructor if a trailing slash was supplied in the URIish.
	* <p>
	* All files within the remote repository start with
	* <code>keyPrefix + "/"</code>.
	*/
	private final String keyPrefix;

	TransportAmazonS3(final Repository local, final URIish uri)
	throws NotSupportedException {
	super(local, uri);

	Properties props = loadProperties();
	File directory = local.getDirectory();
	if (!props.containsKey("tmpdir") && directory != null) //$NON-NLS-1$
	props.put("tmpdir", directory.getPath()); //$NON-NLS-1$

	s3 = new AmazonS3(props);
	bucket = uri.getHost();

	String p = uri.getPath();
	if (p.startsWith("/")) //$NON-NLS-1$
	p = p.substring(1);
	if (p.endsWith("/")) //$NON-NLS-1$
	p = p.substring(0, p.length() - 1);
	keyPrefix = p;
	}

	private Properties loadProperties() throws NotSupportedException {
	if (local.getDirectory() != null) {
	File propsFile = new File(local.getDirectory(), uri.getUser());
	if (propsFile.isFile())
	return loadPropertiesFile(propsFile);
	}

	File propsFile = new File(local.getFS().userHome(), uri.getUser());
	if (propsFile.isFile())
	return loadPropertiesFile(propsFile);

	Properties props = new Properties();
	String user = uri.getUser();
	String pass = uri.getPass();
	if (user != null && pass != null) {
	props.setProperty("accesskey", user); //$NON-NLS-1$
	props.setProperty("secretkey", pass); //$NON-NLS-1$
	} else
	throw new NotSupportedException(MessageFormat.format(
	JGitText.get().cannotReadFile, propsFile));
	return props;
	}

	private static Properties loadPropertiesFile(File propsFile)
	throws NotSupportedException {
	try {
	return AmazonS3.properties(propsFile);
	} catch (IOException e) {
	throw new NotSupportedException(MessageFormat.format(
	JGitText.get().cannotReadFile, propsFile), e);
	}
	}

	@Override
	public FetchConnection openFetch() throws TransportException {
	final DatabaseS3 c = new DatabaseS3(bucket, keyPrefix + "/objects"); //$NON-NLS-1$
	final WalkFetchConnection r = new WalkFetchConnection(this, c);
	r.available(c.readAdvertisedRefs());
	return r;
	}

	@Override
	public PushConnection openPush() throws TransportException {
	final DatabaseS3 c = new DatabaseS3(bucket, keyPrefix + "/objects"); //$NON-NLS-1$
	final WalkPushConnection r = new WalkPushConnection(this, c);
	r.available(c.readAdvertisedRefs());
	return r;
	}

	@Override
	public void close() {
	// No explicit connections are maintained.
	}

	class DatabaseS3 extends WalkRemoteObjectDatabase {
	private final String bucketName;

	private final String objectsKey;

	DatabaseS3(final String b, final String o) {
	bucketName = b;
	objectsKey = o;
	}

	private String resolveKey(String subpath) {
	if (subpath.endsWith("/")) //$NON-NLS-1$
	subpath = subpath.substring(0, subpath.length() - 1);
	String k = objectsKey;
	while (subpath.startsWith(ROOT_DIR)) {
	k = k.substring(0, k.lastIndexOf('/'));
	subpath = subpath.substring(3);
	}
	return k + "/" + subpath; //$NON-NLS-1$
	}

	@Override
	URIish getURI() {
	URIish u = new URIish();
	u = u.setScheme(S3_SCHEME);
	u = u.setHost(bucketName);
	u = u.setPath("/" + objectsKey); //$NON-NLS-1$
	return u;
	}

	@Override
	Collection<WalkRemoteObjectDatabase> getAlternates() throws IOException {
	try {
	return readAlternates(INFO_ALTERNATES);
	} catch (FileNotFoundException err) {
	// Fall through.
	}
	return null;
	}

	@Override
	WalkRemoteObjectDatabase openAlternate(final String location)
	throws IOException {
	return new DatabaseS3(bucketName, resolveKey(location));
	}

	@Override
	Collection<String> getPackNames() throws IOException {
	final HashSet<String> have = new HashSet<>();
	have.addAll(s3.list(bucket, resolveKey("pack"))); //$NON-NLS-1$

	final Collection<String> packs = new ArrayList<>();
	for (final String n : have) {
	if (!n.startsWith("pack-") \|\| !n.endsWith(".pack")) //$NON-NLS-1$ //$NON-NLS-2$
	continue;

	final String in = n.substring(0, n.length() - 5) + ".idx"; //$NON-NLS-1$
	if (have.contains(in))
	packs.add(n);
	}
	return packs;
	}

	@Override
	FileStream open(final String path) throws IOException {
	final URLConnection c = s3.get(bucket, resolveKey(path));
	final InputStream raw = c.getInputStream();
	final InputStream in = s3.decrypt(c);
	final int len = c.getContentLength();
	return new FileStream(in, raw == in ? len : -1);
	}

	@Override
	void deleteFile(final String path) throws IOException {
	s3.delete(bucket, resolveKey(path));
	}

	@Override
	OutputStream writeFile(final String path,
	final ProgressMonitor monitor, final String monitorTask)
	throws IOException {
	return s3.beginPut(bucket, resolveKey(path), monitor, monitorTask);
	}

	@Override
	void writeFile(final String path, final byte[] data) throws IOException {
	s3.put(bucket, resolveKey(path), data);
	}

	Map<String, Ref> readAdvertisedRefs() throws TransportException {
	final TreeMap<String, Ref> avail = new TreeMap<>();
	readPackedRefs(avail);
	readLooseRefs(avail);
	readRef(avail, Constants.HEAD);
	return avail;
	}

	private void readLooseRefs(final TreeMap<String, Ref> avail)
	throws TransportException {
	try {
	for (final String n : s3.list(bucket, resolveKey(ROOT_DIR
	+ "refs"))) //$NON-NLS-1$
	readRef(avail, "refs/" + n); //$NON-NLS-1$
	} catch (IOException e) {
	throw new TransportException(getURI(), JGitText.get().cannotListRefs, e);
	}
	}

	private Ref readRef(final TreeMap<String, Ref> avail, final String rn)
	throws TransportException {
	final String s;
	String ref = ROOT_DIR + rn;
	try {
	final BufferedReader br = openReader(ref);
	try {
	s = br.readLine();
	} finally {
	br.close();
	}
	} catch (FileNotFoundException noRef) {
	return null;
	} catch (IOException err) {
	throw new TransportException(getURI(), MessageFormat.format(
	JGitText.get().transportExceptionReadRef, ref), err);
	}

	if (s == null)
	throw new TransportException(getURI(), MessageFormat.format(JGitText.get().transportExceptionEmptyRef, rn));

	if (s.startsWith("ref: ")) { //$NON-NLS-1$
	final String target = s.substring("ref: ".length()); //$NON-NLS-1$
	Ref r = avail.get(target);
	if (r == null)
	r = readRef(avail, target);
	if (r == null)
	r = new ObjectIdRef.Unpeeled(Ref.Storage.NEW, target, null);
	r = new SymbolicRef(rn, r);
	avail.put(r.getName(), r);
	return r;
	}

	if (ObjectId.isId(s)) {
	final Ref r = new ObjectIdRef.Unpeeled(loose(avail.get(rn)),
	rn, ObjectId.fromString(s));
	avail.put(r.getName(), r);
	return r;
	}

	throw new TransportException(getURI(), MessageFormat.format(JGitText.get().transportExceptionBadRef, rn, s));
	}

	private Storage loose(final Ref r) {
	if (r != null && r.getStorage() == Storage.PACKED)
	return Storage.LOOSE_PACKED;
	return Storage.LOOSE;
	}

	@Override
	void close() {
	// We do not maintain persistent connections.
	}
	}
	}