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>

1 files changed, 14 insertions, 13 deletions

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 {