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1   /*
2    * Copyright (C) 2008, 2009 Google Inc.
3    * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
4    * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
5    * Copyright (C) 2008, 2022 Shawn O. Pearce <spearce@spearce.org> and others
6    *
7    * This program and the accompanying materials are made available under the
8    * terms of the Eclipse Distribution License v. 1.0 which is available at
9    * https://www.eclipse.org/org/documents/edl-v10.php.
10   *
11   * SPDX-License-Identifier: BSD-3-Clause
12   */
13  
14  package org.eclipse.jgit.transport;
15  
16  import static java.nio.charset.StandardCharsets.UTF_8;
17  import static java.util.Objects.requireNonNull;
18  
19  import java.io.BufferedReader;
20  import java.io.IOException;
21  import java.io.InputStreamReader;
22  import java.io.OutputStream;
23  import java.io.PrintStream;
24  import java.lang.ref.WeakReference;
25  import java.lang.reflect.Field;
26  import java.lang.reflect.Modifier;
27  import java.net.URISyntaxException;
28  import java.net.URL;
29  import java.text.MessageFormat;
30  import java.time.Instant;
31  import java.util.ArrayList;
32  import java.util.Collection;
33  import java.util.Collections;
34  import java.util.Enumeration;
35  import java.util.LinkedHashSet;
36  import java.util.LinkedList;
37  import java.util.List;
38  import java.util.Map;
39  import java.util.Vector;
40  import java.util.concurrent.CopyOnWriteArrayList;
41  
42  import org.eclipse.jgit.annotations.NonNull;
43  import org.eclipse.jgit.annotations.Nullable;
44  import org.eclipse.jgit.errors.NotSupportedException;
45  import org.eclipse.jgit.errors.TransportException;
46  import org.eclipse.jgit.hooks.Hooks;
47  import org.eclipse.jgit.hooks.PrePushHook;
48  import org.eclipse.jgit.internal.JGitText;
49  import org.eclipse.jgit.lib.Constants;
50  import org.eclipse.jgit.lib.ObjectChecker;
51  import org.eclipse.jgit.lib.ObjectId;
52  import org.eclipse.jgit.lib.ProgressMonitor;
53  import org.eclipse.jgit.lib.Ref;
54  import org.eclipse.jgit.lib.Repository;
55  import org.eclipse.jgit.storage.pack.PackConfig;
56  
57  /**
58   * Connects two Git repositories together and copies objects between them.
59   * <p>
60   * A transport can be used for either fetching (copying objects into the
61   * caller's repository from the remote repository) or pushing (copying objects
62   * into the remote repository from the caller's repository). Each transport
63   * implementation is responsible for the details associated with establishing
64   * the network connection(s) necessary for the copy, as well as actually
65   * shuffling data back and forth.
66   * <p>
67   * Transport instances and the connections they create are not thread-safe.
68   * Callers must ensure a transport is accessed by only one thread at a time.
69   */
70  public abstract class Transport implements AutoCloseable {
71  	/** Type of operation a Transport is being opened for. */
72  	public enum Operation {
73  		/** Transport is to fetch objects locally. */
74  		FETCH,
75  		/** Transport is to push objects remotely. */
76  		PUSH;
77  	}
78  
79  	private static final List<WeakReference<TransportProtocol>> protocols =
80  		new CopyOnWriteArrayList<>();
81  
82  	static {
83  		// Registration goes backwards in order of priority.
84  		register(TransportLocal.PROTO_LOCAL);
85  		register(TransportBundleFile.PROTO_BUNDLE);
86  		register(TransportAmazonS3.PROTO_S3);
87  		register(TransportGitAnon.PROTO_GIT);
88  		register(TransportSftp.PROTO_SFTP);
89  		register(TransportHttp.PROTO_FTP);
90  		register(TransportHttp.PROTO_HTTP);
91  		register(TransportGitSsh.PROTO_SSH);
92  
93  		registerByService();
94  	}
95  
96  	private static void registerByService() {
97  		ClassLoader ldr = Thread.currentThread().getContextClassLoader();
98  		if (ldr == null)
99  			ldr = Transport.class.getClassLoader();
100 		Enumeration<URL> catalogs = catalogs(ldr);
101 		while (catalogs.hasMoreElements())
102 			scan(ldr, catalogs.nextElement());
103 	}
104 
105 	private static Enumeration<URL> catalogs(ClassLoader ldr) {
106 		try {
107 			String prefix = "META-INF/services/"; //$NON-NLS-1$
108 			String name = prefix + Transport.class.getName();
109 			return ldr.getResources(name);
110 		} catch (IOException err) {
111 			return new Vector<URL>().elements();
112 		}
113 	}
114 
115 	private static void scan(ClassLoader ldr, URL url) {
116 		try (BufferedReader br = new BufferedReader(
117 				new InputStreamReader(url.openStream(), UTF_8))) {
118 			String line;
119 			while ((line = br.readLine()) != null) {
120 				line = line.trim();
121 				if (line.length() == 0)
122 					continue;
123 				int comment = line.indexOf('#');
124 				if (comment == 0)
125 					continue;
126 				if (comment != -1)
127 					line = line.substring(0, comment).trim();
128 				load(ldr, line);
129 			}
130 		} catch (IOException e) {
131 			// Ignore errors
132 		}
133 	}
134 
135 	private static void load(ClassLoader ldr, String cn) {
136 		Class<?> clazz;
137 		try {
138 			clazz = Class.forName(cn, false, ldr);
139 		} catch (ClassNotFoundException notBuiltin) {
140 			// Doesn't exist, even though the service entry is present.
141 			//
142 			return;
143 		}
144 
145 		for (Field f : clazz.getDeclaredFields()) {
146 			if ((f.getModifiers() & Modifier.STATIC) == Modifier.STATIC
147 					&& TransportProtocol.class.isAssignableFrom(f.getType())) {
148 				TransportProtocol proto;
149 				try {
150 					proto = (TransportProtocol) f.get(null);
151 				} catch (IllegalArgumentException | IllegalAccessException e) {
152 					// If we cannot access the field, don't.
153 					continue;
154 				}
155 				if (proto != null)
156 					register(proto);
157 			}
158 		}
159 	}
160 
161 	/**
162 	 * Register a TransportProtocol instance for use during open.
163 	 * <p>
164 	 * Protocol definitions are held by WeakReference, allowing them to be
165 	 * garbage collected when the calling application drops all strongly held
166 	 * references to the TransportProtocol. Therefore applications should use a
167 	 * singleton pattern as described in
168 	 * {@link org.eclipse.jgit.transport.TransportProtocol}'s class
169 	 * documentation to ensure their protocol does not get disabled by garbage
170 	 * collection earlier than expected.
171 	 * <p>
172 	 * The new protocol is registered in front of all earlier protocols, giving
173 	 * it higher priority than the built-in protocol definitions.
174 	 *
175 	 * @param proto
176 	 *            the protocol definition. Must not be null.
177 	 */
178 	public static void register(TransportProtocol proto) {
179 		protocols.add(0, new WeakReference<>(proto));
180 	}
181 
182 	/**
183 	 * Unregister a TransportProtocol instance.
184 	 * <p>
185 	 * Unregistering a protocol usually isn't necessary, as protocols are held
186 	 * by weak references and will automatically clear when they are garbage
187 	 * collected by the JVM. Matching is handled by reference equality, so the
188 	 * exact reference given to {@link #register(TransportProtocol)} must be
189 	 * used.
190 	 *
191 	 * @param proto
192 	 *            the exact object previously given to register.
193 	 */
194 	public static void unregister(TransportProtocol proto) {
195 		for (WeakReference<TransportProtocol> ref : protocols) {
196 			TransportProtocol refProto = ref.get();
197 			if (refProto == null || refProto == proto)
198 				protocols.remove(ref);
199 		}
200 	}
201 
202 	/**
203 	 * Obtain a copy of the registered protocols.
204 	 *
205 	 * @return an immutable copy of the currently registered protocols.
206 	 */
207 	public static List<TransportProtocol> getTransportProtocols() {
208 		int cnt = protocols.size();
209 		List<TransportProtocol> res = new ArrayList<>(cnt);
210 		for (WeakReference<TransportProtocol> ref : protocols) {
211 			TransportProtocol proto = ref.get();
212 			if (proto != null)
213 				res.add(proto);
214 			else
215 				protocols.remove(ref);
216 		}
217 		return Collections.unmodifiableList(res);
218 	}
219 
220 	/**
221 	 * Open a new transport instance to connect two repositories.
222 	 * <p>
223 	 * This method assumes
224 	 * {@link org.eclipse.jgit.transport.Transport.Operation#FETCH}.
225 	 *
226 	 * @param local
227 	 *            existing local repository.
228 	 * @param remote
229 	 *            location of the remote repository - may be URI or remote
230 	 *            configuration name.
231 	 * @return the new transport instance. Never null. In case of multiple URIs
232 	 *         in remote configuration, only the first is chosen.
233 	 * @throws java.net.URISyntaxException
234 	 *             the location is not a remote defined in the configuration
235 	 *             file and is not a well-formed URL.
236 	 * @throws org.eclipse.jgit.errors.NotSupportedException
237 	 *             the protocol specified is not supported.
238 	 * @throws org.eclipse.jgit.errors.TransportException
239 	 *             the transport cannot open this URI.
240 	 */
241 	public static Transport open(Repository local, String remote)
242 			throws NotSupportedException, URISyntaxException,
243 			TransportException {
244 		return open(local, remote, Operation.FETCH);
245 	}
246 
247 	/**
248 	 * Open a new transport instance to connect two repositories.
249 	 *
250 	 * @param local
251 	 *            existing local repository.
252 	 * @param remote
253 	 *            location of the remote repository - may be URI or remote
254 	 *            configuration name.
255 	 * @param op
256 	 *            planned use of the returned Transport; the URI may differ
257 	 *            based on the type of connection desired.
258 	 * @return the new transport instance. Never null. In case of multiple URIs
259 	 *         in remote configuration, only the first is chosen.
260 	 * @throws java.net.URISyntaxException
261 	 *             the location is not a remote defined in the configuration
262 	 *             file and is not a well-formed URL.
263 	 * @throws org.eclipse.jgit.errors.NotSupportedException
264 	 *             the protocol specified is not supported.
265 	 * @throws org.eclipse.jgit.errors.TransportException
266 	 *             the transport cannot open this URI.
267 	 */
268 	public static Transport open(final Repository local, final String remote,
269 			final Operation op) throws NotSupportedException,
270 			URISyntaxException, TransportException {
271 		if (local != null) {
272 			final RemoteConfig cfg = new RemoteConfig(local.getConfig(), remote);
273 			if (doesNotExist(cfg)) {
274 				return open(local, new URIish(remote), null);
275 			}
276 			return open(local, cfg, op);
277 		}
278 		return open(new URIish(remote));
279 
280 	}
281 
282 	/**
283 	 * Open new transport instances to connect two repositories.
284 	 * <p>
285 	 * This method assumes
286 	 * {@link org.eclipse.jgit.transport.Transport.Operation#FETCH}.
287 	 *
288 	 * @param local
289 	 *            existing local repository.
290 	 * @param remote
291 	 *            location of the remote repository - may be URI or remote
292 	 *            configuration name.
293 	 * @return the list of new transport instances for every URI in remote
294 	 *         configuration.
295 	 * @throws java.net.URISyntaxException
296 	 *             the location is not a remote defined in the configuration
297 	 *             file and is not a well-formed URL.
298 	 * @throws org.eclipse.jgit.errors.NotSupportedException
299 	 *             the protocol specified is not supported.
300 	 * @throws org.eclipse.jgit.errors.TransportException
301 	 *             the transport cannot open this URI.
302 	 */
303 	public static List<Transport> openAll(final Repository local,
304 			final String remote) throws NotSupportedException,
305 			URISyntaxException, TransportException {
306 		return openAll(local, remote, Operation.FETCH);
307 	}
308 
309 	/**
310 	 * Open new transport instances to connect two repositories.
311 	 *
312 	 * @param local
313 	 *            existing local repository.
314 	 * @param remote
315 	 *            location of the remote repository - may be URI or remote
316 	 *            configuration name.
317 	 * @param op
318 	 *            planned use of the returned Transport; the URI may differ
319 	 *            based on the type of connection desired.
320 	 * @return the list of new transport instances for every URI in remote
321 	 *         configuration.
322 	 * @throws java.net.URISyntaxException
323 	 *             the location is not a remote defined in the configuration
324 	 *             file and is not a well-formed URL.
325 	 * @throws org.eclipse.jgit.errors.NotSupportedException
326 	 *             the protocol specified is not supported.
327 	 * @throws org.eclipse.jgit.errors.TransportException
328 	 *             the transport cannot open this URI.
329 	 */
330 	public static List<Transport> openAll(final Repository local,
331 			final String remote, final Operation op)
332 			throws NotSupportedException, URISyntaxException,
333 			TransportException {
334 		final RemoteConfig cfg = new RemoteConfig(local.getConfig(), remote);
335 		if (doesNotExist(cfg)) {
336 			final ArrayList<Transport> transports = new ArrayList<>(1);
337 			transports.add(open(local, new URIish(remote), null));
338 			return transports;
339 		}
340 		return openAll(local, cfg, op);
341 	}
342 
343 	/**
344 	 * Open a new transport instance to connect two repositories.
345 	 * <p>
346 	 * This method assumes
347 	 * {@link org.eclipse.jgit.transport.Transport.Operation#FETCH}.
348 	 *
349 	 * @param local
350 	 *            existing local repository.
351 	 * @param cfg
352 	 *            configuration describing how to connect to the remote
353 	 *            repository.
354 	 * @return the new transport instance. Never null. In case of multiple URIs
355 	 *         in remote configuration, only the first is chosen.
356 	 * @throws org.eclipse.jgit.errors.NotSupportedException
357 	 *             the protocol specified is not supported.
358 	 * @throws org.eclipse.jgit.errors.TransportException
359 	 *             the transport cannot open this URI.
360 	 * @throws java.lang.IllegalArgumentException
361 	 *             if provided remote configuration doesn't have any URI
362 	 *             associated.
363 	 */
364 	public static Transport open(Repository local, RemoteConfig cfg)
365 			throws NotSupportedException, TransportException {
366 		return open(local, cfg, Operation.FETCH);
367 	}
368 
369 	/**
370 	 * Open a new transport instance to connect two repositories.
371 	 *
372 	 * @param local
373 	 *            existing local repository.
374 	 * @param cfg
375 	 *            configuration describing how to connect to the remote
376 	 *            repository.
377 	 * @param op
378 	 *            planned use of the returned Transport; the URI may differ
379 	 *            based on the type of connection desired.
380 	 * @return the new transport instance. Never null. In case of multiple URIs
381 	 *         in remote configuration, only the first is chosen.
382 	 * @throws org.eclipse.jgit.errors.NotSupportedException
383 	 *             the protocol specified is not supported.
384 	 * @throws org.eclipse.jgit.errors.TransportException
385 	 *             the transport cannot open this URI.
386 	 * @throws java.lang.IllegalArgumentException
387 	 *             if provided remote configuration doesn't have any URI
388 	 *             associated.
389 	 */
390 	public static Transport open(final Repository local,
391 			final RemoteConfig cfg, final Operation op)
392 			throws NotSupportedException, TransportException {
393 		final List<URIish> uris = getURIs(cfg, op);
394 		if (uris.isEmpty())
395 			throw new IllegalArgumentException(MessageFormat.format(
396 					JGitText.get().remoteConfigHasNoURIAssociated, cfg.getName()));
397 		final Transport tn = open(local, uris.get(0), cfg.getName());
398 		tn.applyConfig(cfg);
399 		return tn;
400 	}
401 
402 	/**
403 	 * Open new transport instances to connect two repositories.
404 	 * <p>
405 	 * This method assumes
406 	 * {@link org.eclipse.jgit.transport.Transport.Operation#FETCH}.
407 	 *
408 	 * @param local
409 	 *            existing local repository.
410 	 * @param cfg
411 	 *            configuration describing how to connect to the remote
412 	 *            repository.
413 	 * @return the list of new transport instances for every URI in remote
414 	 *         configuration.
415 	 * @throws org.eclipse.jgit.errors.NotSupportedException
416 	 *             the protocol specified is not supported.
417 	 * @throws org.eclipse.jgit.errors.TransportException
418 	 *             the transport cannot open this URI.
419 	 */
420 	public static List<Transport> openAll(final Repository local,
421 			final RemoteConfig cfg) throws NotSupportedException,
422 			TransportException {
423 		return openAll(local, cfg, Operation.FETCH);
424 	}
425 
426 	/**
427 	 * Open new transport instances to connect two repositories.
428 	 *
429 	 * @param local
430 	 *            existing local repository.
431 	 * @param cfg
432 	 *            configuration describing how to connect to the remote
433 	 *            repository.
434 	 * @param op
435 	 *            planned use of the returned Transport; the URI may differ
436 	 *            based on the type of connection desired.
437 	 * @return the list of new transport instances for every URI in remote
438 	 *         configuration.
439 	 * @throws org.eclipse.jgit.errors.NotSupportedException
440 	 *             the protocol specified is not supported.
441 	 * @throws org.eclipse.jgit.errors.TransportException
442 	 *             the transport cannot open this URI.
443 	 */
444 	public static List<Transport> openAll(final Repository local,
445 			final RemoteConfig cfg, final Operation op)
446 			throws NotSupportedException, TransportException {
447 		final List<URIish> uris = getURIs(cfg, op);
448 		final List<Transport> transports = new ArrayList<>(uris.size());
449 		for (URIish uri : uris) {
450 			final Transport tn = open(local, uri, cfg.getName());
451 			tn.applyConfig(cfg);
452 			transports.add(tn);
453 		}
454 		return transports;
455 	}
456 
457 	private static List<URIish> getURIs(final RemoteConfig cfg,
458 			final Operation op) {
459 		switch (op) {
460 		case FETCH:
461 			return cfg.getURIs();
462 		case PUSH: {
463 			List<URIish> uris = cfg.getPushURIs();
464 			if (uris.isEmpty())
465 				uris = cfg.getURIs();
466 			return uris;
467 		}
468 		default:
469 			throw new IllegalArgumentException(op.toString());
470 		}
471 	}
472 
473 	private static boolean doesNotExist(RemoteConfig cfg) {
474 		return cfg.getURIs().isEmpty() && cfg.getPushURIs().isEmpty();
475 	}
476 
477 	/**
478 	 * Open a new transport instance to connect two repositories.
479 	 *
480 	 * @param local
481 	 *            existing local repository.
482 	 * @param uri
483 	 *            location of the remote repository.
484 	 * @return the new transport instance. Never null.
485 	 * @throws org.eclipse.jgit.errors.NotSupportedException
486 	 *             the protocol specified is not supported.
487 	 * @throws org.eclipse.jgit.errors.TransportException
488 	 *             the transport cannot open this URI.
489 	 */
490 	public static Transport open(Repository local, URIish uri)
491 			throws NotSupportedException, TransportException {
492 		return open(local, uri, null);
493 	}
494 
495 	/**
496 	 * Open a new transport instance to connect two repositories.
497 	 *
498 	 * @param local
499 	 *            existing local repository.
500 	 * @param uri
501 	 *            location of the remote repository.
502 	 * @param remoteName
503 	 *            name of the remote, if the remote as configured in
504 	 *            {@code local}; otherwise null.
505 	 * @return the new transport instance. Never null.
506 	 * @throws org.eclipse.jgit.errors.NotSupportedException
507 	 *             the protocol specified is not supported.
508 	 * @throws org.eclipse.jgit.errors.TransportException
509 	 *             the transport cannot open this URI.
510 	 */
511 	public static Transport open(Repository local, URIish uri, String remoteName)
512 			throws NotSupportedException, TransportException {
513 		for (WeakReference<TransportProtocol> ref : protocols) {
514 			TransportProtocol proto = ref.get();
515 			if (proto == null) {
516 				protocols.remove(ref);
517 				continue;
518 			}
519 
520 			if (proto.canHandle(uri, local, remoteName)) {
521 				Transport tn = proto.open(uri, local, remoteName);
522 				tn.prePush = Hooks.prePush(local, tn.hookOutRedirect);
523 				tn.prePush.setRemoteLocation(uri.toString());
524 				tn.prePush.setRemoteName(remoteName);
525 				return tn;
526 			}
527 		}
528 
529 		throw new NotSupportedException(MessageFormat.format(JGitText.get().URINotSupported, uri));
530 	}
531 
532 	/**
533 	 * Open a new transport with no local repository.
534 	 * <p>
535 	 * Note that the resulting transport instance can not be used for fetching
536 	 * or pushing, but only for reading remote refs.
537 	 *
538 	 * @param uri a {@link org.eclipse.jgit.transport.URIish} object.
539 	 * @return new Transport instance
540 	 * @throws org.eclipse.jgit.errors.NotSupportedException
541 	 * @throws org.eclipse.jgit.errors.TransportException
542 	 */
543 	public static Transport open(URIish uri) throws NotSupportedException, TransportException {
544 		for (WeakReference<TransportProtocol> ref : protocols) {
545 			TransportProtocol proto = ref.get();
546 			if (proto == null) {
547 				protocols.remove(ref);
548 				continue;
549 			}
550 
551 			if (proto.canHandle(uri, null, null))
552 				return proto.open(uri);
553 		}
554 
555 		throw new NotSupportedException(MessageFormat.format(JGitText.get().URINotSupported, uri));
556 	}
557 
558 	/**
559 	 * Convert push remote refs update specification from
560 	 * {@link org.eclipse.jgit.transport.RefSpec} form to
561 	 * {@link org.eclipse.jgit.transport.RemoteRefUpdate}. Conversion expands
562 	 * wildcards by matching source part to local refs. expectedOldObjectId in
563 	 * RemoteRefUpdate is set when specified in leases. Tracking branch is
564 	 * configured if RefSpec destination matches source of any fetch ref spec
565 	 * for this transport remote configuration.
566 	 *
567 	 * @param db
568 	 *            local database.
569 	 * @param specs
570 	 *            collection of RefSpec to convert.
571 	 * @param leases
572 	 *            map from ref to lease (containing expected old object id)
573 	 * @param fetchSpecs
574 	 *            fetch specifications used for finding localtracking refs. May
575 	 *            be null or empty collection.
576 	 * @return collection of set up
577 	 *         {@link org.eclipse.jgit.transport.RemoteRefUpdate}.
578 	 * @throws java.io.IOException
579 	 *             when problem occurred during conversion or specification set
580 	 *             up: most probably, missing objects or refs.
581 	 * @since 4.7
582 	 */
583 	public static Collection<RemoteRefUpdate> findRemoteRefUpdatesFor(
584 			final Repository db, final Collection<RefSpec> specs,
585 			final Map<String, RefLeaseSpec> leases,
586 			Collection<RefSpec> fetchSpecs) throws IOException {
587 		if (fetchSpecs == null)
588 			fetchSpecs = Collections.emptyList();
589 		final List<RemoteRefUpdate> result = new LinkedList<>();
590 		final Collection<RefSpec> procRefs = expandPushWildcardsFor(db, specs);
591 
592 		for (RefSpec spec : procRefs) {
593 			if (spec.isMatching()) {
594 				result.add(new RemoteRefUpdate(db, spec.isForceUpdate(),
595 						fetchSpecs));
596 				continue;
597 			}
598 			String srcSpec = spec.getSource();
599 			final Ref srcRef = db.findRef(srcSpec);
600 			if (srcRef != null)
601 				srcSpec = srcRef.getName();
602 
603 			String destSpec = spec.getDestination();
604 			if (destSpec == null) {
605 				// No destination (no-colon in ref-spec), DWIMery assumes src
606 				//
607 				destSpec = srcSpec;
608 			}
609 
610 			if (srcRef != null && !destSpec.startsWith(Constants.R_REFS)) {
611 				// Assume the same kind of ref at the destination, e.g.
612 				// "refs/heads/foo:master", DWIMery assumes master is also
613 				// under "refs/heads/".
614 				//
615 				final String n = srcRef.getName();
616 				final int kindEnd = n.indexOf('/', Constants.R_REFS.length());
617 				destSpec = n.substring(0, kindEnd + 1) + destSpec;
618 			}
619 
620 			final boolean forceUpdate = spec.isForceUpdate();
621 			final String localName = findTrackingRefName(destSpec, fetchSpecs);
622 			final RefLeaseSpec leaseSpec = leases.get(destSpec);
623 			final ObjectId expected = leaseSpec == null ? null :
624 				db.resolve(leaseSpec.getExpected());
625 			final RemoteRefUpdate rru = new RemoteRefUpdate(db, srcSpec,
626 					destSpec, forceUpdate, localName, expected);
627 			result.add(rru);
628 		}
629 		return result;
630 	}
631 
632 	/**
633 	 * Convert push remote refs update specification from
634 	 * {@link org.eclipse.jgit.transport.RefSpec} form to
635 	 * {@link org.eclipse.jgit.transport.RemoteRefUpdate}. Conversion expands
636 	 * wildcards by matching source part to local refs. expectedOldObjectId in
637 	 * RemoteRefUpdate is always set as null. Tracking branch is configured if
638 	 * RefSpec destination matches source of any fetch ref spec for this
639 	 * transport remote configuration.
640 	 *
641 	 * @param db
642 	 *            local database.
643 	 * @param specs
644 	 *            collection of RefSpec to convert.
645 	 * @param fetchSpecs
646 	 *            fetch specifications used for finding localtracking refs. May
647 	 *            be null or empty collection.
648 	 * @return collection of set up
649 	 *         {@link org.eclipse.jgit.transport.RemoteRefUpdate}.
650 	 * @throws java.io.IOException
651 	 *             when problem occurred during conversion or specification set
652 	 *             up: most probably, missing objects or refs.
653 	 */
654 	public static Collection<RemoteRefUpdate> findRemoteRefUpdatesFor(
655 			final Repository db, final Collection<RefSpec> specs,
656 			Collection<RefSpec> fetchSpecs) throws IOException {
657 		return findRemoteRefUpdatesFor(db, specs, Collections.emptyMap(),
658 					       fetchSpecs);
659 	}
660 
661 	private static Collection<RefSpec> expandPushWildcardsFor(
662 			final Repository db, final Collection<RefSpec> specs)
663 			throws IOException {
664 		final Collection<RefSpec> procRefs = new LinkedHashSet<>();
665 
666 		List<Ref> localRefs = null;
667 		for (RefSpec spec : specs) {
668 			if (!spec.isMatching() && spec.isWildcard()) {
669 				if (localRefs == null) {
670 					localRefs = db.getRefDatabase().getRefs();
671 				}
672 				for (Ref localRef : localRefs) {
673 					if (spec.matchSource(localRef)) {
674 						procRefs.add(spec.expandFromSource(localRef));
675 					}
676 				}
677 			} else {
678 				procRefs.add(spec);
679 			}
680 		}
681 		return procRefs;
682 	}
683 
684 	static String findTrackingRefName(final String remoteName,
685 			final Collection<RefSpec> fetchSpecs) {
686 		// try to find matching tracking refs
687 		for (RefSpec fetchSpec : fetchSpecs) {
688 			if (fetchSpec.matchSource(remoteName)) {
689 				if (fetchSpec.isWildcard()) {
690 					return fetchSpec.expandFromSource(remoteName)
691 							.getDestination();
692 				}
693 				return fetchSpec.getDestination();
694 			}
695 		}
696 		return null;
697 	}
698 
699 	/**
700 	 * Default setting for {@link #fetchThin} option.
701 	 */
702 	public static final boolean DEFAULT_FETCH_THIN = true;
703 
704 	/**
705 	 * Default setting for {@link #pushThin} option.
706 	 */
707 	public static final boolean DEFAULT_PUSH_THIN = false;
708 
709 	/**
710 	 * Specification for fetch or push operations, to fetch or push all tags.
711 	 * Acts as --tags.
712 	 */
713 	public static final RefSpec REFSPEC_TAGS = new RefSpec(
714 			"refs/tags/*:refs/tags/*"); //$NON-NLS-1$
715 
716 	/**
717 	 * Specification for push operation, to push all refs under refs/heads. Acts
718 	 * as --all.
719 	 */
720 	public static final RefSpec REFSPEC_PUSH_ALL = new RefSpec(
721 			"refs/heads/*:refs/heads/*"); //$NON-NLS-1$
722 
723 	/** The repository this transport fetches into, or pushes out of. */
724 	protected final Repository local;
725 
726 	/** The URI used to create this transport. */
727 	protected final URIish uri;
728 
729 	/** Name of the upload pack program, if it must be executed. */
730 	private String optionUploadPack = RemoteConfig.DEFAULT_UPLOAD_PACK;
731 
732 	/** Specifications to apply during fetch. */
733 	private List<RefSpec> fetch = Collections.emptyList();
734 
735 	/**
736 	 * How {@link #fetch(ProgressMonitor, Collection)} should handle tags.
737 	 * <p>
738 	 * We default to {@link TagOpt#NO_TAGS} so as to avoid fetching annotated
739 	 * tags during one-shot fetches used for later merges. This prevents
740 	 * dragging down tags from repositories that we do not have established
741 	 * tracking branches for. If we do not track the source repository, we most
742 	 * likely do not care about any tags it publishes.
743 	 */
744 	private TagOpt tagopt = TagOpt.NO_TAGS;
745 
746 	/** Should fetch request thin-pack if remote repository can produce it. */
747 	private boolean fetchThin = DEFAULT_FETCH_THIN;
748 
749 	/** Name of the receive pack program, if it must be executed. */
750 	private String optionReceivePack = RemoteConfig.DEFAULT_RECEIVE_PACK;
751 
752 	/** Specifications to apply during push. */
753 	private List<RefSpec> push = Collections.emptyList();
754 
755 	/** Should push produce thin-pack when sending objects to remote repository. */
756 	private boolean pushThin = DEFAULT_PUSH_THIN;
757 
758 	/** Should push be all-or-nothing atomic behavior? */
759 	private boolean pushAtomic;
760 
761 	/** Should push just check for operation result, not really push. */
762 	private boolean dryRun;
763 
764 	/** Should an incoming (fetch) transfer validate objects? */
765 	private ObjectChecker objectChecker;
766 
767 	/** Should refs no longer on the source be pruned from the destination? */
768 	private boolean removeDeletedRefs;
769 
770 	private FilterSpec filterSpec = FilterSpec.NO_FILTER;
771 
772 	/** Timeout in seconds to wait before aborting an IO read or write. */
773 	private int timeout;
774 
775 	/** Pack configuration used by this transport to make pack file. */
776 	private PackConfig packConfig;
777 
778 	/** Assists with authentication the connection. */
779 	private CredentialsProvider credentialsProvider;
780 
781 	/** The option strings associated with the push operation. */
782 	private List<String> pushOptions;
783 
784 	private PrintStream hookOutRedirect;
785 
786 	private PrePushHook prePush;
787 
788 	private Integer depth;
789 
790 	private Instant deepenSince;
791 
792 	private List<String> deepenNots = new ArrayList<>();
793 
794 	@Nullable
795 	TransferConfig.ProtocolVersion protocol;
796 
797 	/**
798 	 * Create a new transport instance.
799 	 *
800 	 * @param local
801 	 *            the repository this instance will fetch into, or push out of.
802 	 *            This must be the repository passed to
803 	 *            {@link #open(Repository, URIish)}.
804 	 * @param uri
805 	 *            the URI used to access the remote repository. This must be the
806 	 *            URI passed to {@link #open(Repository, URIish)}.
807 	 */
808 	protected Transport(Repository local, URIish uri) {
809 		final TransferConfig tc = local.getConfig().get(TransferConfig.KEY);
810 		this.local = local;
811 		this.uri = uri;
812 		this.protocol = tc.protocolVersion;
813 		this.objectChecker = tc.newObjectChecker();
814 		this.credentialsProvider = CredentialsProvider.getDefault();
815 		prePush = Hooks.prePush(local, hookOutRedirect);
816 	}
817 
818 	/**
819 	 * Create a minimal transport instance not tied to a single repository.
820 	 *
821 	 * @param uri
822 	 *            a {@link org.eclipse.jgit.transport.URIish} object.
823 	 */
824 	protected Transport(URIish uri) {
825 		this.uri = uri;
826 		this.local = null;
827 		this.objectChecker = new ObjectChecker();
828 		this.credentialsProvider = CredentialsProvider.getDefault();
829 	}
830 
831 	/**
832 	 * Get the URI this transport connects to.
833 	 * <p>
834 	 * Each transport instance connects to at most one URI at any point in time.
835 	 *
836 	 * @return the URI describing the location of the remote repository.
837 	 */
838 	public URIish getURI() {
839 		return uri;
840 	}
841 
842 	/**
843 	 * Get the name of the remote executable providing upload-pack service.
844 	 *
845 	 * @return typically "git-upload-pack".
846 	 */
847 	public String getOptionUploadPack() {
848 		return optionUploadPack;
849 	}
850 
851 	/**
852 	 * Set the name of the remote executable providing upload-pack services.
853 	 *
854 	 * @param where
855 	 *            name of the executable.
856 	 */
857 	public void setOptionUploadPack(String where) {
858 		if (where != null && where.length() > 0)
859 			optionUploadPack = where;
860 		else
861 			optionUploadPack = RemoteConfig.DEFAULT_UPLOAD_PACK;
862 	}
863 
864 	/**
865 	 * Get the description of how annotated tags should be treated during fetch.
866 	 *
867 	 * @return option indicating the behavior of annotated tags in fetch.
868 	 */
869 	public TagOpt getTagOpt() {
870 		return tagopt;
871 	}
872 
873 	/**
874 	 * Set the description of how annotated tags should be treated on fetch.
875 	 *
876 	 * @param option
877 	 *            method to use when handling annotated tags.
878 	 */
879 	public void setTagOpt(TagOpt option) {
880 		tagopt = option != null ? option : TagOpt.AUTO_FOLLOW;
881 	}
882 
883 	/**
884 	 * Default setting is: {@link #DEFAULT_FETCH_THIN}
885 	 *
886 	 * @return true if fetch should request thin-pack when possible; false
887 	 *         otherwise
888 	 * @see PackTransport
889 	 */
890 	public boolean isFetchThin() {
891 		return fetchThin;
892 	}
893 
894 	/**
895 	 * Set the thin-pack preference for fetch operation. Default setting is:
896 	 * {@link #DEFAULT_FETCH_THIN}
897 	 *
898 	 * @param fetchThin
899 	 *            true when fetch should request thin-pack when possible; false
900 	 *            when it shouldn't
901 	 * @see PackTransport
902 	 */
903 	public void setFetchThin(boolean fetchThin) {
904 		this.fetchThin = fetchThin;
905 	}
906 
907 	/**
908 	 * Whether fetch will verify if received objects are formatted correctly.
909 	 *
910 	 * @return true if fetch will verify received objects are formatted
911 	 *         correctly. Validating objects requires more CPU time on the
912 	 *         client side of the connection.
913 	 */
914 	public boolean isCheckFetchedObjects() {
915 		return getObjectChecker() != null;
916 	}
917 
918 	/**
919 	 * Configure if checking received objects is enabled
920 	 *
921 	 * @param check
922 	 *            true to enable checking received objects; false to assume all
923 	 *            received objects are valid.
924 	 * @see #setObjectChecker(ObjectChecker)
925 	 */
926 	public void setCheckFetchedObjects(boolean check) {
927 		if (check && objectChecker == null)
928 			setObjectChecker(new ObjectChecker());
929 		else if (!check && objectChecker != null)
930 			setObjectChecker(null);
931 	}
932 
933 	/**
934 	 * Get configured object checker for received objects
935 	 *
936 	 * @return configured object checker for received objects, or null.
937 	 * @since 3.6
938 	 */
939 	public ObjectChecker getObjectChecker() {
940 		return objectChecker;
941 	}
942 
943 	/**
944 	 * Set the object checker to verify each received object with
945 	 *
946 	 * @param impl
947 	 *            if non-null the object checking instance to verify each
948 	 *            received object with; null to disable object checking.
949 	 * @since 3.6
950 	 */
951 	public void setObjectChecker(ObjectChecker impl) {
952 		objectChecker = impl;
953 	}
954 
955 	/**
956 	 * Default setting is:
957 	 * {@link org.eclipse.jgit.transport.RemoteConfig#DEFAULT_RECEIVE_PACK}
958 	 *
959 	 * @return remote executable providing receive-pack service for pack
960 	 *         transports.
961 	 * @see PackTransport
962 	 */
963 	public String getOptionReceivePack() {
964 		return optionReceivePack;
965 	}
966 
967 	/**
968 	 * Set remote executable providing receive-pack service for pack transports.
969 	 * Default setting is:
970 	 * {@link org.eclipse.jgit.transport.RemoteConfig#DEFAULT_RECEIVE_PACK}
971 	 *
972 	 * @param optionReceivePack
973 	 *            remote executable, if null or empty default one is set;
974 	 */
975 	public void setOptionReceivePack(String optionReceivePack) {
976 		if (optionReceivePack != null && optionReceivePack.length() > 0)
977 			this.optionReceivePack = optionReceivePack;
978 		else
979 			this.optionReceivePack = RemoteConfig.DEFAULT_RECEIVE_PACK;
980 	}
981 
982 	/**
983 	 * Default setting is: {@value #DEFAULT_PUSH_THIN}
984 	 *
985 	 * @return true if push should produce thin-pack in pack transports
986 	 * @see PackTransport
987 	 */
988 	public boolean isPushThin() {
989 		return pushThin;
990 	}
991 
992 	/**
993 	 * Set thin-pack preference for push operation. Default setting is:
994 	 * {@value #DEFAULT_PUSH_THIN}
995 	 *
996 	 * @param pushThin
997 	 *            true when push should produce thin-pack in pack transports;
998 	 *            false when it shouldn't
999 	 * @see PackTransport
1000 	 */
1001 	public void setPushThin(boolean pushThin) {
1002 		this.pushThin = pushThin;
1003 	}
1004 
1005 	/**
1006 	 * Default setting is false.
1007 	 *
1008 	 * @return true if push requires all-or-nothing atomic behavior.
1009 	 * @since 4.2
1010 	 */
1011 	public boolean isPushAtomic() {
1012 		return pushAtomic;
1013 	}
1014 
1015 	/**
1016 	 * Request atomic push (all references succeed, or none do).
1017 	 * <p>
1018 	 * Server must also support atomic push. If the server does not support the
1019 	 * feature the push will abort without making changes.
1020 	 *
1021 	 * @param atomic
1022 	 *            true when push should be an all-or-nothing operation.
1023 	 * @see PackTransport
1024 	 * @since 4.2
1025 	 */
1026 	public void setPushAtomic(boolean atomic) {
1027 		this.pushAtomic = atomic;
1028 	}
1029 
1030 	/**
1031 	 * Whether destination refs should be removed if they no longer exist at the
1032 	 * source repository.
1033 	 *
1034 	 * @return true if destination refs should be removed if they no longer
1035 	 *         exist at the source repository.
1036 	 */
1037 	public boolean isRemoveDeletedRefs() {
1038 		return removeDeletedRefs;
1039 	}
1040 
1041 	/**
1042 	 * Set whether or not to remove refs which no longer exist in the source.
1043 	 * <p>
1044 	 * If true, refs at the destination repository (local for fetch, remote for
1045 	 * push) are deleted if they no longer exist on the source side (remote for
1046 	 * fetch, local for push).
1047 	 * <p>
1048 	 * False by default, as this may cause data to become unreachable, and
1049 	 * eventually be deleted on the next GC.
1050 	 *
1051 	 * @param remove true to remove refs that no longer exist.
1052 	 */
1053 	public void setRemoveDeletedRefs(boolean remove) {
1054 		removeDeletedRefs = remove;
1055 	}
1056 
1057 	/**
1058 	 * @return the blob limit value set with {@link #setFilterBlobLimit} or
1059 	 *         {@link #setFilterSpec(FilterSpec)}, or -1 if no blob limit value
1060 	 *         was set
1061 	 * @since 5.0
1062 	 * @deprecated Use {@link #getFilterSpec()} instead
1063 	 */
1064 	@Deprecated
1065 	public final long getFilterBlobLimit() {
1066 		return filterSpec.getBlobLimit();
1067 	}
1068 
1069 	/**
1070 	 * @param bytes exclude blobs of size greater than this
1071 	 * @since 5.0
1072 	 * @deprecated Use {@link #setFilterSpec(FilterSpec)} instead
1073 	 */
1074 	@Deprecated
1075 	public final void setFilterBlobLimit(long bytes) {
1076 		setFilterSpec(FilterSpec.withBlobLimit(bytes));
1077 	}
1078 
1079 	/**
1080 	 * @return the last filter spec set with {@link #setFilterSpec(FilterSpec)},
1081 	 *         or {@link FilterSpec#NO_FILTER} if it was never invoked.
1082 	 * @since 5.4
1083 	 */
1084 	public final FilterSpec getFilterSpec() {
1085 		return filterSpec;
1086 	}
1087 
1088 	/**
1089 	 * @param filter a new filter to use for this transport
1090 	 * @since 5.4
1091 	 */
1092 	public final void setFilterSpec(@NonNull FilterSpec filter) {
1093 		filterSpec = requireNonNull(filter);
1094 	}
1095 
1096 
1097 	/**
1098 	 * Retrieves the depth for a shallow clone.
1099 	 *
1100 	 * @return the depth, or {@code null} if none set
1101 	 * @since 6.3
1102 	 */
1103 	public final Integer getDepth() {
1104 		return depth;
1105 	}
1106 
1107 	/**
1108 	 * Limits fetching to the specified number of commits from the tip of each
1109 	 * remote branch history.
1110 	 *
1111 	 * @param depth
1112 	 *            the depth
1113 	 * @since 6.3
1114 	 */
1115 	public final void setDepth(int depth) {
1116 		if (depth < 1) {
1117 			throw new IllegalArgumentException(JGitText.get().depthMustBeAt1);
1118 		}
1119 		this.depth = Integer.valueOf(depth);
1120 	}
1121 
1122 	/**
1123 	 * Limits fetching to the specified number of commits from the tip of each
1124 	 * remote branch history.
1125 	 *
1126 	 * @param depth
1127 	 *            the depth, or {@code null} to unset the depth
1128 	 * @since 6.3
1129 	 */
1130 	public final void setDepth(Integer depth) {
1131 		if (depth != null && depth.intValue() < 1) {
1132 			throw new IllegalArgumentException(JGitText.get().depthMustBeAt1);
1133 		}
1134 		this.depth = depth;
1135 	}
1136 
1137 	/**
1138 	 * @return the deepen-since for a shallow clone
1139 	 * @since 6.3
1140 	 */
1141 	public final Instant getDeepenSince() {
1142 		return deepenSince;
1143 	}
1144 
1145 	/**
1146 	 * Deepen or shorten the history of a shallow repository to include all reachable commits after a specified time.
1147 	 *
1148 	 * @param deepenSince the deepen-since. Must not be {@code null}
1149 	 * @since 6.3
1150 	 */
1151 	public final void setDeepenSince(@NonNull Instant deepenSince) {
1152 		this.deepenSince = deepenSince;
1153 	}
1154 
1155 	/**
1156 	 * @return the deepen-not for a shallow clone
1157 	 * @since 6.3
1158 	 */
1159 	public final List<String> getDeepenNots() {
1160 		return deepenNots;
1161 	}
1162 
1163 	/**
1164 	 * Deepen or shorten the history of a shallow repository to exclude commits reachable from a specified remote branch or tag.
1165 	 *
1166 	 * @param deepenNots the deepen-not. Must not be {@code null}
1167 	 * @since 6.3
1168 	 */
1169 	public final void setDeepenNots(@NonNull List<String> deepenNots) {
1170 		this.deepenNots = deepenNots;
1171 	}
1172 
1173 	/**
1174 	 * Apply provided remote configuration on this transport.
1175 	 *
1176 	 * @param cfg
1177 	 *            configuration to apply on this transport.
1178 	 */
1179 	public void applyConfig(RemoteConfig cfg) {
1180 		setOptionUploadPack(cfg.getUploadPack());
1181 		setOptionReceivePack(cfg.getReceivePack());
1182 		setTagOpt(cfg.getTagOpt());
1183 		fetch = cfg.getFetchRefSpecs();
1184 		push = cfg.getPushRefSpecs();
1185 		timeout = cfg.getTimeout();
1186 	}
1187 
1188 	/**
1189 	 * Whether push operation should just check for possible result and not
1190 	 * really update remote refs
1191 	 *
1192 	 * @return true if push operation should just check for possible result and
1193 	 *         not really update remote refs, false otherwise - when push should
1194 	 *         act normally.
1195 	 */
1196 	public boolean isDryRun() {
1197 		return dryRun;
1198 	}
1199 
1200 	/**
1201 	 * Set dry run option for push operation.
1202 	 *
1203 	 * @param dryRun
1204 	 *            true if push operation should just check for possible result
1205 	 *            and not really update remote refs, false otherwise - when push
1206 	 *            should act normally.
1207 	 */
1208 	public void setDryRun(boolean dryRun) {
1209 		this.dryRun = dryRun;
1210 	}
1211 
1212 	/**
1213 	 * Get timeout (in seconds) before aborting an IO operation.
1214 	 *
1215 	 * @return timeout (in seconds) before aborting an IO operation.
1216 	 */
1217 	public int getTimeout() {
1218 		return timeout;
1219 	}
1220 
1221 	/**
1222 	 * Set the timeout before willing to abort an IO call.
1223 	 *
1224 	 * @param seconds
1225 	 *            number of seconds to wait (with no data transfer occurring)
1226 	 *            before aborting an IO read or write operation with this
1227 	 *            remote.
1228 	 */
1229 	public void setTimeout(int seconds) {
1230 		timeout = seconds;
1231 	}
1232 
1233 	/**
1234 	 * Get the configuration used by the pack generator to make packs.
1235 	 *
1236 	 * If {@link #setPackConfig(PackConfig)} was previously given null a new
1237 	 * PackConfig is created on demand by this method using the source
1238 	 * repository's settings.
1239 	 *
1240 	 * @return the pack configuration. Never null.
1241 	 */
1242 	public PackConfig getPackConfig() {
1243 		if (packConfig == null)
1244 			packConfig = new PackConfig(local);
1245 		return packConfig;
1246 	}
1247 
1248 	/**
1249 	 * Set the configuration used by the pack generator.
1250 	 *
1251 	 * @param pc
1252 	 *            configuration controlling packing parameters. If null the
1253 	 *            source repository's settings will be used.
1254 	 */
1255 	public void setPackConfig(PackConfig pc) {
1256 		packConfig = pc;
1257 	}
1258 
1259 	/**
1260 	 * A credentials provider to assist with authentication connections..
1261 	 *
1262 	 * @param credentialsProvider
1263 	 *            the credentials provider, or null if there is none
1264 	 */
1265 	public void setCredentialsProvider(CredentialsProvider credentialsProvider) {
1266 		this.credentialsProvider = credentialsProvider;
1267 	}
1268 
1269 	/**
1270 	 * The configured credentials provider.
1271 	 *
1272 	 * @return the credentials provider, or null if no credentials provider is
1273 	 *         associated with this transport.
1274 	 */
1275 	public CredentialsProvider getCredentialsProvider() {
1276 		return credentialsProvider;
1277 	}
1278 
1279 	/**
1280 	 * Get the option strings associated with the push operation
1281 	 *
1282 	 * @return the option strings associated with the push operation
1283 	 * @since 4.5
1284 	 */
1285 	public List<String> getPushOptions() {
1286 		return pushOptions;
1287 	}
1288 
1289 	/**
1290 	 * Sets the option strings associated with the push operation.
1291 	 *
1292 	 * @param pushOptions
1293 	 *            null if push options are unsupported
1294 	 * @since 4.5
1295 	 */
1296 	public void setPushOptions(List<String> pushOptions) {
1297 		this.pushOptions = pushOptions;
1298 	}
1299 
1300 	/**
1301 	 * Fetch objects and refs from the remote repository to the local one.
1302 	 * <p>
1303 	 * This is a utility function providing standard fetch behavior. Local
1304 	 * tracking refs associated with the remote repository are automatically
1305 	 * updated if this transport was created from a
1306 	 * {@link org.eclipse.jgit.transport.RemoteConfig} with fetch RefSpecs
1307 	 * defined.
1308 	 *
1309 	 * @param monitor
1310 	 *            progress monitor to inform the user about our processing
1311 	 *            activity. Must not be null. Use
1312 	 *            {@link org.eclipse.jgit.lib.NullProgressMonitor} if progress
1313 	 *            updates are not interesting or necessary.
1314 	 * @param toFetch
1315 	 *            specification of refs to fetch locally. May be null or the
1316 	 *            empty collection to use the specifications from the
1317 	 *            RemoteConfig. May contains regular and negative
1318 	 *            {@link RefSpec}s. Source for each regular RefSpec can't
1319 	 *            be null.
1320 	 * @return information describing the tracking refs updated.
1321 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1322 	 *             this transport implementation does not support fetching
1323 	 *             objects.
1324 	 * @throws org.eclipse.jgit.errors.TransportException
1325 	 *             the remote connection could not be established or object
1326 	 *             copying (if necessary) failed or update specification was
1327 	 *             incorrect.
1328 	 * @since 5.11
1329 	 */
1330 	public FetchResult fetch(final ProgressMonitor monitor,
1331 			Collection<RefSpec> toFetch)
1332 			throws NotSupportedException, TransportException {
1333 		return fetch(monitor, toFetch, null);
1334 	}
1335 
1336 	/**
1337 	 * Fetch objects and refs from the remote repository to the local one.
1338 	 * <p>
1339 	 * This is a utility function providing standard fetch behavior. Local
1340 	 * tracking refs associated with the remote repository are automatically
1341 	 * updated if this transport was created from a
1342 	 * {@link org.eclipse.jgit.transport.RemoteConfig} with fetch RefSpecs
1343 	 * defined.
1344 	 *
1345 	 * @param monitor
1346 	 *            progress monitor to inform the user about our processing
1347 	 *            activity. Must not be null. Use
1348 	 *            {@link org.eclipse.jgit.lib.NullProgressMonitor} if progress
1349 	 *            updates are not interesting or necessary.
1350 	 * @param toFetch
1351 	 *            specification of refs to fetch locally. May be null or the
1352 	 *            empty collection to use the specifications from the
1353 	 *            RemoteConfig. May contain regular and negative
1354 	 *            {@link RefSpec}s. Source for each regular RefSpec can't
1355 	 *            be null.
1356 	 * @param branch
1357 	 *            the initial branch to check out when cloning the repository.
1358 	 *            Can be specified as ref name (<code>refs/heads/master</code>),
1359 	 *            branch name (<code>master</code>) or tag name
1360 	 *            (<code>v1.2.3</code>). The default is to use the branch
1361 	 *            pointed to by the cloned repository's HEAD and can be
1362 	 *            requested by passing {@code null} or <code>HEAD</code>.
1363 	 * @return information describing the tracking refs updated.
1364 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1365 	 *             this transport implementation does not support fetching
1366 	 *             objects.
1367 	 * @throws org.eclipse.jgit.errors.TransportException
1368 	 *             the remote connection could not be established or object
1369 	 *             copying (if necessary) failed or update specification was
1370 	 *             incorrect.
1371 	 * @since 5.11
1372 	 */
1373 	public FetchResult fetch(final ProgressMonitor monitor,
1374 			Collection<RefSpec> toFetch, String branch)
1375 			throws NotSupportedException,
1376 			TransportException {
1377 		if (toFetch == null || toFetch.isEmpty()) {
1378 			// If the caller did not ask for anything use the defaults.
1379 			//
1380 			if (fetch.isEmpty())
1381 				throw new TransportException(JGitText.get().nothingToFetch);
1382 			toFetch = fetch;
1383 		} else if (!fetch.isEmpty()) {
1384 			// If the caller asked for something specific without giving
1385 			// us the local tracking branch see if we can update any of
1386 			// the local tracking branches without incurring additional
1387 			// object transfer overheads.
1388 			//
1389 			final Collection<RefSpec> tmp = new ArrayList<>(toFetch);
1390 			for (RefSpec requested : toFetch) {
1391 				final String reqSrc = requested.getSource();
1392 				for (RefSpec configured : fetch) {
1393 					final String cfgSrc = configured.getSource();
1394 					final String cfgDst = configured.getDestination();
1395 					if (cfgSrc.equals(reqSrc) && cfgDst != null) {
1396 						tmp.add(configured);
1397 						break;
1398 					}
1399 				}
1400 			}
1401 			toFetch = tmp;
1402 		}
1403 
1404 		final FetchResult result = new FetchResult();
1405 		new FetchProcess(this, toFetch).execute(monitor, result, branch);
1406 
1407 		local.autoGC(monitor);
1408 
1409 		return result;
1410 	}
1411 
1412 	/**
1413 	 * Push objects and refs from the local repository to the remote one.
1414 	 * <p>
1415 	 * This is a utility function providing standard push behavior. It updates
1416 	 * remote refs and send there necessary objects according to remote ref
1417 	 * update specification. After successful remote ref update, associated
1418 	 * locally stored tracking branch is updated if set up accordingly. Detailed
1419 	 * operation result is provided after execution.
1420 	 * <p>
1421 	 * For setting up remote ref update specification from ref spec, see helper
1422 	 * method {@link #findRemoteRefUpdatesFor(Collection)}, predefined refspecs
1423 	 * ({@link #REFSPEC_TAGS}, {@link #REFSPEC_PUSH_ALL}) or consider using
1424 	 * directly {@link org.eclipse.jgit.transport.RemoteRefUpdate} for more
1425 	 * possibilities.
1426 	 * <p>
1427 	 * When {@link #isDryRun()} is true, result of this operation is just
1428 	 * estimation of real operation result, no real action is performed.
1429 	 *
1430 	 * @see RemoteRefUpdate
1431 	 * @param monitor
1432 	 *            progress monitor to inform the user about our processing
1433 	 *            activity. Must not be null. Use
1434 	 *            {@link org.eclipse.jgit.lib.NullProgressMonitor} if progress
1435 	 *            updates are not interesting or necessary.
1436 	 * @param toPush
1437 	 *            specification of refs to push. May be null or the empty
1438 	 *            collection to use the specifications from the RemoteConfig
1439 	 *            converted by {@link #findRemoteRefUpdatesFor(Collection)}. No
1440 	 *            more than 1 RemoteRefUpdate with the same remoteName is
1441 	 *            allowed. These objects are modified during this call.
1442 	 * @param out
1443 	 *            output stream to write messages to
1444 	 * @return information about results of remote refs updates, tracking refs
1445 	 *         updates and refs advertised by remote repository.
1446 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1447 	 *             this transport implementation does not support pushing
1448 	 *             objects.
1449 	 * @throws org.eclipse.jgit.errors.TransportException
1450 	 *             the remote connection could not be established or object
1451 	 *             copying (if necessary) failed at I/O or protocol level or
1452 	 *             update specification was incorrect.
1453 	 * @since 3.0
1454 	 */
1455 	public PushResult push(final ProgressMonitor monitor,
1456 			Collection<RemoteRefUpdate> toPush, OutputStream out)
1457 			throws NotSupportedException,
1458 			TransportException {
1459 		if (toPush == null || toPush.isEmpty()) {
1460 			// If the caller did not ask for anything use the defaults.
1461 			try {
1462 				toPush = findRemoteRefUpdatesFor(push);
1463 			} catch (final IOException e) {
1464 				throw new TransportException(MessageFormat.format(
1465 						JGitText.get().problemWithResolvingPushRefSpecsLocally, e.getMessage()), e);
1466 			}
1467 			if (toPush.isEmpty())
1468 				throw new TransportException(JGitText.get().nothingToPush);
1469 		}
1470 
1471 		final PushProcess pushProcess = new PushProcess(this, toPush, prePush,
1472 				out);
1473 		return pushProcess.execute(monitor);
1474 	}
1475 
1476 	/**
1477 	 * Push objects and refs from the local repository to the remote one.
1478 	 * <p>
1479 	 * This is a utility function providing standard push behavior. It updates
1480 	 * remote refs and sends necessary objects according to remote ref update
1481 	 * specification. After successful remote ref update, associated locally
1482 	 * stored tracking branch is updated if set up accordingly. Detailed
1483 	 * operation result is provided after execution.
1484 	 * <p>
1485 	 * For setting up remote ref update specification from ref spec, see helper
1486 	 * method {@link #findRemoteRefUpdatesFor(Collection)}, predefined refspecs
1487 	 * ({@link #REFSPEC_TAGS}, {@link #REFSPEC_PUSH_ALL}) or consider using
1488 	 * directly {@link org.eclipse.jgit.transport.RemoteRefUpdate} for more
1489 	 * possibilities.
1490 	 * <p>
1491 	 * When {@link #isDryRun()} is true, result of this operation is just
1492 	 * estimation of real operation result, no real action is performed.
1493 	 *
1494 	 * @see RemoteRefUpdate
1495 	 * @param monitor
1496 	 *            progress monitor to inform the user about our processing
1497 	 *            activity. Must not be null. Use
1498 	 *            {@link org.eclipse.jgit.lib.NullProgressMonitor} if progress
1499 	 *            updates are not interesting or necessary.
1500 	 * @param toPush
1501 	 *            specification of refs to push. May be null or the empty
1502 	 *            collection to use the specifications from the RemoteConfig
1503 	 *            converted by {@link #findRemoteRefUpdatesFor(Collection)}. No
1504 	 *            more than 1 RemoteRefUpdate with the same remoteName is
1505 	 *            allowed. These objects are modified during this call.
1506 	 * @return information about results of remote refs updates, tracking refs
1507 	 *         updates and refs advertised by remote repository.
1508 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1509 	 *             this transport implementation does not support pushing
1510 	 *             objects.
1511 	 * @throws org.eclipse.jgit.errors.TransportException
1512 	 *             the remote connection could not be established or object
1513 	 *             copying (if necessary) failed at I/O or protocol level or
1514 	 *             update specification was incorrect.
1515 	 */
1516 	public PushResult push(final ProgressMonitor monitor,
1517 			Collection<RemoteRefUpdate> toPush) throws NotSupportedException,
1518 			TransportException {
1519 		return push(monitor, toPush, null);
1520 	}
1521 
1522 	/**
1523 	 * Convert push remote refs update specification from
1524 	 * {@link org.eclipse.jgit.transport.RefSpec} form to
1525 	 * {@link org.eclipse.jgit.transport.RemoteRefUpdate}. Conversion expands
1526 	 * wildcards by matching source part to local refs. expectedOldObjectId in
1527 	 * RemoteRefUpdate is always set as null. Tracking branch is configured if
1528 	 * RefSpec destination matches source of any fetch ref spec for this
1529 	 * transport remote configuration.
1530 	 * <p>
1531 	 * Conversion is performed for context of this transport (database, fetch
1532 	 * specifications).
1533 	 *
1534 	 * @param specs
1535 	 *            collection of RefSpec to convert.
1536 	 * @return collection of set up
1537 	 *         {@link org.eclipse.jgit.transport.RemoteRefUpdate}.
1538 	 * @throws java.io.IOException
1539 	 *             when problem occurred during conversion or specification set
1540 	 *             up: most probably, missing objects or refs.
1541 	 */
1542 	public Collection<RemoteRefUpdate> findRemoteRefUpdatesFor(
1543 			final Collection<RefSpec> specs) throws IOException {
1544 		return findRemoteRefUpdatesFor(local, specs, Collections.emptyMap(),
1545 					       fetch);
1546 	}
1547 
1548 	/**
1549 	 * Convert push remote refs update specification from
1550 	 * {@link org.eclipse.jgit.transport.RefSpec} form to
1551 	 * {@link org.eclipse.jgit.transport.RemoteRefUpdate}. Conversion expands
1552 	 * wildcards by matching source part to local refs. expectedOldObjectId in
1553 	 * RemoteRefUpdate is set according to leases. Tracking branch is configured
1554 	 * if RefSpec destination matches source of any fetch ref spec for this
1555 	 * transport remote configuration.
1556 	 * <p>
1557 	 * Conversion is performed for context of this transport (database, fetch
1558 	 * specifications).
1559 	 *
1560 	 * @param specs
1561 	 *            collection of RefSpec to convert.
1562 	 * @param leases
1563 	 *            map from ref to lease (containing expected old object id)
1564 	 * @return collection of set up
1565 	 *         {@link org.eclipse.jgit.transport.RemoteRefUpdate}.
1566 	 * @throws java.io.IOException
1567 	 *             when problem occurred during conversion or specification set
1568 	 *             up: most probably, missing objects or refs.
1569 	 * @since 4.7
1570 	 */
1571 	public Collection<RemoteRefUpdate> findRemoteRefUpdatesFor(
1572 			final Collection<RefSpec> specs,
1573 			final Map<String, RefLeaseSpec> leases) throws IOException {
1574 		return findRemoteRefUpdatesFor(local, specs, leases,
1575 					       fetch);
1576 	}
1577 
1578 	/**
1579 	 * Begins a new connection for fetching from the remote repository.
1580 	 * <p>
1581 	 * If the transport has no local repository, the fetch connection can only
1582 	 * be used for reading remote refs.
1583 	 *
1584 	 * @return a fresh connection to fetch from the remote repository.
1585 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1586 	 *             the implementation does not support fetching.
1587 	 * @throws org.eclipse.jgit.errors.TransportException
1588 	 *             the remote connection could not be established.
1589 	 */
1590 	public abstract FetchConnection openFetch() throws NotSupportedException,
1591 			TransportException;
1592 
1593 	/**
1594 	 * Begins a new connection for fetching from the remote repository.
1595 	 * <p>
1596 	 * If the transport has no local repository, the fetch connection can only
1597 	 * be used for reading remote refs.
1598 	 * </p>
1599 	 * <p>
1600 	 * If the server supports git protocol V2, the {@link RefSpec}s and the
1601 	 * additional patterns, if any, are used to restrict the server's ref
1602 	 * advertisement to matching refs only.
1603 	 * </p>
1604 	 * <p>
1605 	 * Transports that want to support git protocol V2 <em>must</em> override
1606 	 * this; the default implementation ignores its arguments and calls
1607 	 * {@link #openFetch()}.
1608 	 * </p>
1609 	 *
1610 	 * @param refSpecs
1611 	 *            that will be fetched via
1612 	 *            {@link FetchConnection#fetch(ProgressMonitor, Collection, java.util.Set, OutputStream)} later
1613 	 * @param additionalPatterns
1614 	 *            that will be set as ref prefixes if the server supports git
1615 	 *            protocol V2; {@code null} values are ignored
1616 	 *
1617 	 * @return a fresh connection to fetch from the remote repository.
1618 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1619 	 *             the implementation does not support fetching.
1620 	 * @throws org.eclipse.jgit.errors.TransportException
1621 	 *             the remote connection could not be established.
1622 	 * @since 5.11
1623 	 */
1624 	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
1625 			String... additionalPatterns)
1626 			throws NotSupportedException, TransportException {
1627 		return openFetch();
1628 	}
1629 
1630 	/**
1631 	 * Begins a new connection for pushing into the remote repository.
1632 	 *
1633 	 * @return a fresh connection to push into the remote repository.
1634 	 * @throws org.eclipse.jgit.errors.NotSupportedException
1635 	 *             the implementation does not support pushing.
1636 	 * @throws org.eclipse.jgit.errors.TransportException
1637 	 *             the remote connection could not be established
1638 	 */
1639 	public abstract PushConnection openPush() throws NotSupportedException,
1640 			TransportException;
1641 
1642 	/**
1643 	 * {@inheritDoc}
1644 	 * <p>
1645 	 * Close any resources used by this transport.
1646 	 * <p>
1647 	 * If the remote repository is contacted by a network socket this method
1648 	 * must close that network socket, disconnecting the two peers. If the
1649 	 * remote repository is actually local (same system) this method must close
1650 	 * any open file handles used to read the "remote" repository.
1651 	 * <p>
1652 	 * {@code AutoClosable.close()} declares that it throws {@link Exception}.
1653 	 * Implementers shouldn't throw checked exceptions. This override narrows
1654 	 * the signature to prevent them from doing so.
1655 	 */
1656 	@Override
1657 	public abstract void close();
1658 }