UploadPack: Fix NPE when traversing a tag chain

Always parse RevTags including their body before getting their object
to ensure that non-cached objects are handled correctly when traversing
a tag chain. An NPE in UploadPack#addTagChain will occur on a depth=1
fetch of a branch containing a tag chain and the ref to one of the
middle tags in the chain is deleted.

Change-Id: Ifd8fe868869070b365df926fec5dcd8e64d4f521
Signed-off-by: Kaushik Lingarkar <quic_kaushikl@quicinc.com>

2 files changed, 83 insertions, 13 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
index 7131905850..2b05decb45 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
@@ -2539,6 +2539,75 @@ public class UploadPackTest {
 	}
 
 	@Test
+	public void testSingleBranchShallowCloneTagChainWithReflessTag() throws Exception {
+		RevCommit one = remote.commit().message("1").create();
+		remote.update("master", one);
+		RevTag tag1 = remote.tag("t1", one);
+		remote.lightweightTag("t1", tag1);
+		RevTag tag2 = remote.tag("t2", tag1);
+		RevTag tag3 = remote.tag("t3", tag2);
+		remote.lightweightTag("t3", tag3);
+
+		UploadPack uploadPack = new UploadPack(remote.getRepository());
+
+		ByteArrayOutputStream cli = new ByteArrayOutputStream();
+		PacketLineOut clientWant = new PacketLineOut(cli);
+		clientWant.writeString("want " + one.name() + " include-tag");
+		clientWant.writeString("deepen 1\n");
+		clientWant.end();
+		clientWant.writeString("done\n");
+
+		try (ByteArrayOutputStream serverResponse = new ByteArrayOutputStream()) {
+
+			uploadPack.setPreUploadHook(new PreUploadHook() {
+				@Override
+				public void onBeginNegotiateRound(UploadPack up,
+						Collection<? extends ObjectId> wants, int cntOffered)
+						throws ServiceMayNotContinueException {
+					// Do nothing.
+				}
+
+				@Override
+				public void onEndNegotiateRound(UploadPack up,
+						Collection<? extends ObjectId> wants, int cntCommon,
+						int cntNotFound, boolean ready)
+						throws ServiceMayNotContinueException {
+					// Do nothing.
+				}
+
+				@Override
+				public void onSendPack(UploadPack up,
+						Collection<? extends ObjectId> wants,
+						Collection<? extends ObjectId> haves)
+						throws ServiceMayNotContinueException {
+					// collect pack data
+					serverResponse.reset();
+				}
+			});
+			uploadPack.upload(new ByteArrayInputStream(cli.toByteArray()),
+					serverResponse, System.err);
+			ByteArrayInputStream packReceived = new ByteArrayInputStream(
+					serverResponse.toByteArray());
+			PackLock lock = null;
+			try (ObjectInserter ins = client.newObjectInserter()) {
+				PackParser parser = ins.newPackParser(packReceived);
+				parser.setAllowThin(true);
+				parser.setLockMessage("receive-tag-chain");
+				ProgressMonitor mlc = NullProgressMonitor.INSTANCE;
+				lock = parser.parse(mlc, mlc);
+				ins.flush();
+			} finally {
+				if (lock != null) {
+					lock.unlock();
+				}
+			}
+			InMemoryRepository.MemObjDatabase objDb = client
+					.getObjectDatabase();
+			assertTrue(objDb.has(one.toObjectId()));
+		}
+	}
+
+	@Test
 	public void testSafeToClearRefsInFetchV0() throws Exception {
 		server =
 			new RefCallsCountingRepository(
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index 6cb8fe43c0..0c23c8cadf 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -2405,11 +2405,11 @@ public class UploadPack implements Closeable {
 					if (peeledId == null || objectId == null)
 						continue;
 
-					objectId = ref.getObjectId();
-					if (pw.willInclude(peeledId) && !pw.willInclude(objectId)) {
-						RevObject o = rw.parseAny(objectId);
-						addTagChain(o, pw);
-						pw.addObject(o);
+					if (pw.willInclude(peeledId)) {
+						// We don't need to handle parseTag throwing an
+						// IncorrectObjectTypeException as we only reach
+						// here when ref is an annotated tag
+						addTagChain(rw.parseTag(objectId), pw);
 					}
 				}
 			}
@@ -2459,15 +2459,16 @@ public class UploadPack implements Closeable {
 	}
 
 	private void addTagChain(
-			RevObject o, PackWriter pw) throws IOException {
-		while (Constants.OBJ_TAG == o.getType()) {
-			RevTag t = (RevTag) o;
-			o = t.getObject();
-			if (o.getType() == Constants.OBJ_TAG && !pw.willInclude(o.getId())) {
-				walk.parseBody(o);
-				pw.addObject(o);
+			RevTag tag, PackWriter pw) throws IOException {
+		RevObject o = tag;
+		do {
+			tag = (RevTag) o;
+			walk.parseBody(tag);
+			if (!pw.willInclude(tag.getId())) {
+				pw.addObject(tag);
 			}
-		}
+			o = tag.getObject();
+		} while (Constants.OBJ_TAG == o.getType());
 	}
 
 	private static class ResponseBufferedOutputStream extends OutputStream {