Implement ls-refs in UploadPack

Implement support for Git protocol v2's "ls-refs" command and its
"symrefs" and "peel" parameters.

This adds support for this command to UploadPack but the git://,
ssh://, and git:// transports do not make use of it yet.  That will
have to wait for later patches.

Change-Id: I8abc6bcc6ed4a88c165677ff1245625aca01267b
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jonathan Nieder <jrn@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java

@@ -19,6 +19,7 @@ import org.eclipse.jgit.lib.Sets;
 import org.eclipse.jgit.revwalk.RevBlob;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevTree;
+import org.eclipse.jgit.revwalk.RevTag;
 import org.eclipse.jgit.transport.UploadPack.RequestPolicy;
 import org.eclipse.jgit.transport.resolver.ServiceNotAuthorizedException;
 import org.eclipse.jgit.transport.resolver.ServiceNotEnabledException;
@@ -368,6 +369,7 @@ public class UploadPackTest {
 
 		// capability advertisement (always sent)
 		assertThat(pckIn.readString(), is("version 2"));
+		assertThat(pckIn.readString(), is("ls-refs"));
 		assertTrue(pckIn.readString() == PacketLineIn.END);
 		return recvStream;
 	}
@@ -380,4 +382,83 @@ public class UploadPackTest {
 		assertThat(recvStream.available(), is(0));
 	}
 
+	@Test
+	public void testV2LsRefs() throws Exception {
+		RevCommit tip = remote.commit().message("message").create();
+		remote.update("master", tip);
+		server.updateRef("HEAD").link("refs/heads/master");
+		RevTag tag = remote.tag("tag", tip);
+		remote.update("refs/tags/tag", tag);
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=ls-refs\n", PacketLineIn.END);
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " HEAD"));
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " refs/heads/master"));
+		assertThat(pckIn.readString(), is(tag.toObjectId().getName() + " refs/tags/tag"));
+		assertTrue(pckIn.readString() == PacketLineIn.END);
+	}
+
+	@Test
+	public void testV2LsRefsSymrefs() throws Exception {
+		RevCommit tip = remote.commit().message("message").create();
+		remote.update("master", tip);
+		server.updateRef("HEAD").link("refs/heads/master");
+		RevTag tag = remote.tag("tag", tip);
+		remote.update("refs/tags/tag", tag);
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=ls-refs\n", PacketLineIn.DELIM, "symrefs", PacketLineIn.END);
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " HEAD symref-target:refs/heads/master"));
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " refs/heads/master"));
+		assertThat(pckIn.readString(), is(tag.toObjectId().getName() + " refs/tags/tag"));
+		assertTrue(pckIn.readString() == PacketLineIn.END);
+	}
+
+	@Test
+	public void testV2LsRefsPeel() throws Exception {
+		RevCommit tip = remote.commit().message("message").create();
+		remote.update("master", tip);
+		server.updateRef("HEAD").link("refs/heads/master");
+		RevTag tag = remote.tag("tag", tip);
+		remote.update("refs/tags/tag", tag);
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=ls-refs\n", PacketLineIn.DELIM, "peel", PacketLineIn.END);
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " HEAD"));
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " refs/heads/master"));
+		assertThat(
+			pckIn.readString(),
+			is(tag.toObjectId().getName() + " refs/tags/tag peeled:"
+				+ tip.toObjectId().getName()));
+		assertTrue(pckIn.readString() == PacketLineIn.END);
+	}
+
+	@Test
+	public void testV2LsRefsMultipleCommands() throws Exception {
+		RevCommit tip = remote.commit().message("message").create();
+		remote.update("master", tip);
+		server.updateRef("HEAD").link("refs/heads/master");
+		RevTag tag = remote.tag("tag", tip);
+		remote.update("refs/tags/tag", tag);
+
+		ByteArrayInputStream recvStream = uploadPackV2(
+			"command=ls-refs\n", PacketLineIn.DELIM, "symrefs", "peel", PacketLineIn.END,
+			"command=ls-refs\n", PacketLineIn.DELIM, PacketLineIn.END);
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " HEAD symref-target:refs/heads/master"));
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " refs/heads/master"));
+		assertThat(
+			pckIn.readString(),
+			is(tag.toObjectId().getName() + " refs/tags/tag peeled:"
+				+ tip.toObjectId().getName()));
+		assertTrue(pckIn.readString() == PacketLineIn.END);
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " HEAD"));
+		assertThat(pckIn.readString(), is(tip.toObjectId().getName() + " refs/heads/master"));
+		assertThat(pckIn.readString(), is(tag.toObjectId().getName() + " refs/tags/tag"));
+		assertTrue(pckIn.readString() == PacketLineIn.END);
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/transport/GitProtocolConstants.java

@@ -222,6 +222,13 @@ public class GitProtocolConstants {
 	 */
 	public static final String CAPABILITY_PUSH_OPTIONS = "push-options"; //$NON-NLS-1$
 
+	/**
+	 * The server supports listing refs using protocol v2.
+	 *
+	 * @since 5.0
+	 */
+	public static final String COMMAND_LS_REFS = "ls-refs"; //$NON-NLS-1$
+
 	static enum MultiAck {
 		OFF, CONTINUE, DETAILED;
 	}

org.eclipse.jgit/src/org/eclipse/jgit/transport/RefAdvertiser.java

@@ -53,6 +53,7 @@ import java.nio.CharBuffer;
 import java.nio.charset.CharacterCodingException;
 import java.nio.charset.CharsetEncoder;
 import java.nio.charset.CoderResult;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.Map;
@@ -176,6 +177,11 @@ public abstract class RefAdvertiser {
 
 	boolean first = true;
 
+	private boolean useProtocolV2;
+
+	/* only used in protocol v2 */
+	private final Map<String, String> symrefs = new HashMap<>();
+
 	/**
 	 * Initialize this advertiser with a repository for peeling tags.
 	 *
@@ -186,6 +192,15 @@ public abstract class RefAdvertiser {
 		repository = src;
 	}
 
+	/**
+	 * @param b
+	 *            true if this advertiser should advertise using the
+	 *            protocol v2 format, false otherwise
+	 */
+	public void setUseProtocolV2(boolean b) {
+		useProtocolV2 = b;
+	}
+
 	/**
 	 * Toggle tag peeling.
 	 * <p>
@@ -253,8 +268,12 @@ public abstract class RefAdvertiser {
 	 * @since 3.6
 	 */
 	public void addSymref(String from, String to) {
+		if (useProtocolV2) {
+			symrefs.put(from, to);
+		} else {
 			advertiseCapability(OPTION_SYMREF, from + ':' + to);
 		}
+	}
 
 	/**
 	 * Format an advertisement for the supplied refs.
@@ -273,6 +292,23 @@ public abstract class RefAdvertiser {
 			if (ref.getObjectId() == null)
 				continue;
 
+			if (useProtocolV2) {
+				String symrefPart = symrefs.containsKey(ref.getName())
+					? (" symref-target:" + symrefs.get(ref.getName()))
+					: "";
+				String peelPart = "";
+				if (derefTags) {
+					if (!ref.isPeeled() && repository != null) {
+						ref = repository.peel(ref);
+					}
+					if (ref.getPeeledObjectId() != null) {
+						peelPart = " peeled:" + ref.getPeeledObjectId().getName();
+					}
+				}
+				writeOne(ref.getObjectId().getName() + " " + ref.getName() + symrefPart + peelPart + "\n");
+				continue;
+			}
+
 			advertiseAny(ref.getObjectId(), ref.getName());
 
 			if (!derefTags)

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -44,6 +44,7 @@
 package org.eclipse.jgit.transport;
 
 import static org.eclipse.jgit.lib.RefDatabase.ALL;
+import static org.eclipse.jgit.transport.GitProtocolConstants.COMMAND_LS_REFS;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_AGENT;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_ALLOW_REACHABLE_SHA1_IN_WANT;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_ALLOW_TIP_SHA1_IN_WANT;
@@ -117,6 +118,7 @@ public class UploadPack {
 	// supports protocol version 2.
 	private static final String[] v2CapabilityAdvertisement = {
 		"version 2",
+		COMMAND_LS_REFS
 	};
 
 	/** Policy the server uses to validate client requests */
@@ -864,6 +866,35 @@ public class UploadPack {
 			sendPack(accumulator);
 	}
 
+	private void lsRefsV2() throws IOException {
+		PacketLineOutRefAdvertiser adv = new PacketLineOutRefAdvertiser(pckOut);
+		Map<String, Ref> refs = getAdvertisedOrDefaultRefs();
+		String line;
+
+		adv.setUseProtocolV2(true);
+
+		line = pckIn.readString();
+
+		// Currently, we do not support any capabilities, so the next
+		// line is DELIM if there are arguments or END if not.
+		if (line == PacketLineIn.DELIM) {
+			while ((line = pckIn.readString()) != PacketLineIn.END) {
+				if (line.equals("peel")) {
+					adv.setDerefTags(true);
+				} else if (line.equals("symrefs")) {
+					findSymrefs(adv, refs);
+				} else {
+					throw new PackProtocolException("unexpected " + line);
+				}
+			}
+		} else if (line != PacketLineIn.END) {
+			throw new PackProtocolException("unexpected " + line);
+		}
+
+		adv.send(refs);
+		adv.end();
+	}
+
 	/*
 	 * Returns true if this is the last command and we should tear down the
 	 * connection.
@@ -882,6 +913,10 @@ public class UploadPack {
 			// case.
 			return true;
 		}
+		if (command.equals("command=" + COMMAND_LS_REFS)) {
+			lsRefsV2();
+			return false;
+		}
 		throw new PackProtocolException("unknown command " + command);
 	}