Merge branch 'ds/fix-thin-fix'

"git index-pack --fix-thin" used to abort to prevent a cycle in
delta chains from forming in a corner case even when there is no
such cycle.

* ds/fix-thin-fix:
  index-pack: allow revisiting REF_DELTA chains
  t5309: create failing test for 'git index-pack'
  test-tool: add pack-deltas helper

1 files changed, 32 insertions, 26 deletions

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 147e9b8b47..bb7925bd29 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1108,8 +1108,8 @@ static void *threaded_second_pass(void *data)
 		set_thread_data(data);
 	for (;;) {
 		struct base_data *parent = NULL;
-		struct object_entry *child_obj;
-		struct base_data *child;
+		struct object_entry *child_obj = NULL;
+		struct base_data *child = NULL;
 
 		counter_lock();
 		display_progress(progress, nr_resolved_deltas);
@@ -1136,15 +1136,18 @@ static void *threaded_second_pass(void *data)
 			parent = list_first_entry(&work_head, struct base_data,
 						  list);
 
-			if (parent->ref_first <= parent->ref_last) {
+			while (parent->ref_first <= parent->ref_last) {
 				int offset = ref_deltas[parent->ref_first++].obj_no;
 				child_obj = objects + offset;
-				if (child_obj->real_type != OBJ_REF_DELTA)
-					die("REF_DELTA at offset %"PRIuMAX" already resolved (duplicate base %s?)",
-					    (uintmax_t) child_obj->idx.offset,
-					    oid_to_hex(&parent->obj->idx.oid));
+				if (child_obj->real_type != OBJ_REF_DELTA) {
+					child_obj = NULL;
+					continue;
+				}
 				child_obj->real_type = parent->obj->real_type;
-			} else {
+				break;
+			}
+
+			if (!child_obj && parent->ofs_first <= parent->ofs_last) {
 				child_obj = objects +
 					ofs_deltas[parent->ofs_first++].obj_no;
 				assert(child_obj->real_type == OBJ_OFS_DELTA);
@@ -1177,29 +1180,32 @@ static void *threaded_second_pass(void *data)
 		}
 		work_unlock();
 
-		if (parent) {
-			child = resolve_delta(child_obj, parent);
-			if (!child->children_remaining)
-				FREE_AND_NULL(child->data);
-		} else {
-			child = make_base(child_obj, NULL);
-			if (child->children_remaining) {
-				/*
-				 * Since this child has its own delta children,
-				 * we will need this data in the future.
-				 * Inflate now so that future iterations will
-				 * have access to this object's data while
-				 * outside the work mutex.
-				 */
-				child->data = get_data_from_pack(child_obj);
-				child->size = child_obj->size;
+		if (child_obj) {
+			if (parent) {
+				child = resolve_delta(child_obj, parent);
+				if (!child->children_remaining)
+					FREE_AND_NULL(child->data);
+			} else{
+				child = make_base(child_obj, NULL);
+				if (child->children_remaining) {
+					/*
+					 * Since this child has its own delta children,
+					 * we will need this data in the future.
+					 * Inflate now so that future iterations will
+					 * have access to this object's data while
+					 * outside the work mutex.
+					 */
+					child->data = get_data_from_pack(child_obj);
+					child->size = child_obj->size;
+				}
 			}
 		}
 
 		work_lock();
 		if (parent)
 			parent->retain_data--;
-		if (child->data) {
+
+		if (child && child->data) {
 			/*
 			 * This child has its own children, so add it to
 			 * work_head.
@@ -1208,7 +1214,7 @@ static void *threaded_second_pass(void *data)
 			base_cache_used += child->size;
 			prune_base_data(NULL);
 			free_base_data(child);
-		} else {
+		} else if (child) {
 			/*
 			 * This child does not have its own children. It may be
 			 * the last descendant of its ancestors; free those