1 files changed, 417 insertions, 146 deletions

diff --git a/pack-bitmap.c b/pack-bitmap.c
index 4695aaf6b4..49a8d10d0c 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -12,13 +12,14 @@
 #include "packfile.h"
 #include "repository.h"
 #include "object-store.h"
+#include "list-objects-filter-options.h"
 
 /*
  * An entry on the bitmap index, representing the bitmap for a given
  * commit.
  */
 struct stored_bitmap {
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct ewah_bitmap *root;
 	struct stored_bitmap *xor;
 	int flags;
@@ -60,8 +61,8 @@ struct bitmap_index {
 	struct ewah_bitmap *blobs;
 	struct ewah_bitmap *tags;
 
-	/* Map from SHA1 -> `stored_bitmap` for all the bitmapped commits */
-	khash_sha1 *bitmaps;
+	/* Map from object ID -> `stored_bitmap` for all the bitmapped commits */
+	kh_oid_map_t *bitmaps;
 
 	/* Number of bitmapped commits */
 	uint32_t entry_count;
@@ -80,7 +81,7 @@ struct bitmap_index {
 		struct object **objects;
 		uint32_t *hashes;
 		uint32_t count, alloc;
-		khash_sha1_pos *positions;
+		kh_oid_pos_t *positions;
 	} ext_index;
 
 	/* Bitmap result of the last performed walk */
@@ -138,7 +139,7 @@ static int load_bitmap_header(struct bitmap_index *index)
 {
 	struct bitmap_disk_header *header = (void *)index->map;
 
-	if (index->map_size < sizeof(*header) + 20)
+	if (index->map_size < sizeof(*header) + the_hash_algo->rawsz)
 		return error("Corrupted bitmap index (missing header data)");
 
 	if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
@@ -157,19 +158,19 @@ static int load_bitmap_header(struct bitmap_index *index)
 				"(Git requires BITMAP_OPT_FULL_DAG)");
 
 		if (flags & BITMAP_OPT_HASH_CACHE) {
-			unsigned char *end = index->map + index->map_size - 20;
+			unsigned char *end = index->map + index->map_size - the_hash_algo->rawsz;
 			index->hashes = ((uint32_t *)end) - index->pack->num_objects;
 		}
 	}
 
 	index->entry_count = ntohl(header->entry_count);
-	index->map_pos += sizeof(*header);
+	index->map_pos += sizeof(*header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz;
 	return 0;
 }
 
 static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 					  struct ewah_bitmap *root,
-					  const unsigned char *sha1,
+					  const struct object_id *oid,
 					  struct stored_bitmap *xor_with,
 					  int flags)
 {
@@ -181,15 +182,15 @@ static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 	stored->root = root;
 	stored->xor = xor_with;
 	stored->flags = flags;
-	hashcpy(stored->sha1, sha1);
+	oidcpy(&stored->oid, oid);
 
-	hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &ret);
+	hash_pos = kh_put_oid_map(index->bitmaps, stored->oid, &ret);
 
 	/* a 0 return code means the insertion succeeded with no changes,
 	 * because the SHA1 already existed on the map. this is bad, there
 	 * shouldn't be duplicated commits in the index */
 	if (ret == 0) {
-		error("Duplicate entry in bitmap index: %s", sha1_to_hex(sha1));
+		error("Duplicate entry in bitmap index: %s", oid_to_hex(oid));
 		return NULL;
 	}
 
@@ -221,13 +222,13 @@ static int load_bitmap_entries_v1(struct bitmap_index *index)
 		struct ewah_bitmap *bitmap = NULL;
 		struct stored_bitmap *xor_bitmap = NULL;
 		uint32_t commit_idx_pos;
-		const unsigned char *sha1;
+		struct object_id oid;
 
 		commit_idx_pos = read_be32(index->map, &index->map_pos);
 		xor_offset = read_u8(index->map, &index->map_pos);
 		flags = read_u8(index->map, &index->map_pos);
 
-		sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
+		nth_packed_object_id(&oid, index->pack, commit_idx_pos);
 
 		bitmap = read_bitmap_1(index);
 		if (!bitmap)
@@ -244,7 +245,7 @@ static int load_bitmap_entries_v1(struct bitmap_index *index)
 		}
 
 		recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
-			index, bitmap, sha1, xor_bitmap, flags);
+			index, bitmap, &oid, xor_bitmap, flags);
 	}
 
 	return 0;
@@ -306,9 +307,10 @@ static int load_pack_bitmap(struct bitmap_index *bitmap_git)
 {
 	assert(bitmap_git->map);
 
-	bitmap_git->bitmaps = kh_init_sha1();
-	bitmap_git->ext_index.positions = kh_init_sha1_pos();
-	load_pack_revindex(bitmap_git->pack);
+	bitmap_git->bitmaps = kh_init_oid_map();
+	bitmap_git->ext_index.positions = kh_init_oid_pos();
+	if (load_pack_revindex(bitmap_git->pack))
+		goto failed;
 
 	if (!(bitmap_git->commits = read_bitmap_1(bitmap_git)) ||
 		!(bitmap_git->trees = read_bitmap_1(bitmap_git)) ||
@@ -325,6 +327,13 @@ failed:
 	munmap(bitmap_git->map, bitmap_git->map_size);
 	bitmap_git->map = NULL;
 	bitmap_git->map_size = 0;
+
+	kh_destroy_oid_map(bitmap_git->bitmaps);
+	bitmap_git->bitmaps = NULL;
+
+	kh_destroy_oid_pos(bitmap_git->ext_index.positions);
+	bitmap_git->ext_index.positions = NULL;
+
 	return -1;
 }
 
@@ -362,10 +371,10 @@ struct include_data {
 };
 
 static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
-					   const unsigned char *sha1)
+					   const struct object_id *oid)
 {
-	khash_sha1_pos *positions = bitmap_git->ext_index.positions;
-	khiter_t pos = kh_get_sha1_pos(positions, sha1);
+	kh_oid_pos_t *positions = bitmap_git->ext_index.positions;
+	khiter_t pos = kh_get_oid_pos(positions, *oid);
 
 	if (pos < kh_end(positions)) {
 		int bitmap_pos = kh_value(positions, pos);
@@ -376,9 +385,9 @@ static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
 }
 
 static inline int bitmap_position_packfile(struct bitmap_index *bitmap_git,
-					   const unsigned char *sha1)
+					   const struct object_id *oid)
 {
-	off_t offset = find_pack_entry_one(sha1, bitmap_git->pack);
+	off_t offset = find_pack_entry_one(oid->hash, bitmap_git->pack);
 	if (!offset)
 		return -1;
 
@@ -386,10 +395,10 @@ static inline int bitmap_position_packfile(struct bitmap_index *bitmap_git,
 }
 
 static int bitmap_position(struct bitmap_index *bitmap_git,
-			   const unsigned char *sha1)
+			   const struct object_id *oid)
 {
-	int pos = bitmap_position_packfile(bitmap_git, sha1);
-	return (pos >= 0) ? pos : bitmap_position_extended(bitmap_git, sha1);
+	int pos = bitmap_position_packfile(bitmap_git, oid);
+	return (pos >= 0) ? pos : bitmap_position_extended(bitmap_git, oid);
 }
 
 static int ext_index_add_object(struct bitmap_index *bitmap_git,
@@ -401,7 +410,7 @@ static int ext_index_add_object(struct bitmap_index *bitmap_git,
 	int hash_ret;
 	int bitmap_pos;
 
-	hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
+	hash_pos = kh_put_oid_pos(eindex->positions, object->oid, &hash_ret);
 	if (hash_ret > 0) {
 		if (eindex->count >= eindex->alloc) {
 			eindex->alloc = (eindex->alloc + 16) * 3 / 2;
@@ -431,7 +440,7 @@ static void show_object(struct object *object, const char *name, void *data_)
 	struct bitmap_show_data *data = data_;
 	int bitmap_pos;
 
-	bitmap_pos = bitmap_position(data->bitmap_git, object->oid.hash);
+	bitmap_pos = bitmap_position(data->bitmap_git, &object->oid);
 
 	if (bitmap_pos < 0)
 		bitmap_pos = ext_index_add_object(data->bitmap_git, object,
@@ -446,7 +455,7 @@ static void show_commit(struct commit *commit, void *data)
 
 static int add_to_include_set(struct bitmap_index *bitmap_git,
 			      struct include_data *data,
-			      const unsigned char *sha1,
+			      const struct object_id *oid,
 			      int bitmap_pos)
 {
 	khiter_t hash_pos;
@@ -457,7 +466,7 @@ static int add_to_include_set(struct bitmap_index *bitmap_git,
 	if (bitmap_get(data->base, bitmap_pos))
 		return 0;
 
-	hash_pos = kh_get_sha1(bitmap_git->bitmaps, sha1);
+	hash_pos = kh_get_oid_map(bitmap_git->bitmaps, *oid);
 	if (hash_pos < kh_end(bitmap_git->bitmaps)) {
 		struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, hash_pos);
 		bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
@@ -473,13 +482,13 @@ static int should_include(struct commit *commit, void *_data)
 	struct include_data *data = _data;
 	int bitmap_pos;
 
-	bitmap_pos = bitmap_position(data->bitmap_git, commit->object.oid.hash);
+	bitmap_pos = bitmap_position(data->bitmap_git, &commit->object.oid);
 	if (bitmap_pos < 0)
 		bitmap_pos = ext_index_add_object(data->bitmap_git,
 						  (struct object *)commit,
 						  NULL);
 
-	if (!add_to_include_set(data->bitmap_git, data, commit->object.oid.hash,
+	if (!add_to_include_set(data->bitmap_git, data, &commit->object.oid,
 				bitmap_pos)) {
 		struct commit_list *parent = commit->parents;
 
@@ -517,7 +526,7 @@ static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 		roots = roots->next;
 
 		if (object->type == OBJ_COMMIT) {
-			khiter_t pos = kh_get_sha1(bitmap_git->bitmaps, object->oid.hash);
+			khiter_t pos = kh_get_oid_map(bitmap_git->bitmaps, object->oid);
 
 			if (pos < kh_end(bitmap_git->bitmaps)) {
 				struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
@@ -559,7 +568,7 @@ static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 		int pos;
 
 		roots = roots->next;
-		pos = bitmap_position(bitmap_git, object->oid.hash);
+		pos = bitmap_position(bitmap_git, &object->oid);
 
 		if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 			object->flags &= ~UNINTERESTING;
@@ -598,6 +607,7 @@ static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 }
 
 static void show_extended_objects(struct bitmap_index *bitmap_git,
+				  struct rev_info *revs,
 				  show_reachable_fn show_reach)
 {
 	struct bitmap *objects = bitmap_git->result;
@@ -611,17 +621,48 @@ static void show_extended_objects(struct bitmap_index *bitmap_git,
 			continue;
 
 		obj = eindex->objects[i];
+		if ((obj->type == OBJ_BLOB && !revs->blob_objects) ||
+		    (obj->type == OBJ_TREE && !revs->tree_objects) ||
+		    (obj->type == OBJ_TAG && !revs->tag_objects))
+			continue;
+
 		show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
 	}
 }
 
+static void init_type_iterator(struct ewah_iterator *it,
+			       struct bitmap_index *bitmap_git,
+			       enum object_type type)
+{
+	switch (type) {
+	case OBJ_COMMIT:
+		ewah_iterator_init(it, bitmap_git->commits);
+		break;
+
+	case OBJ_TREE:
+		ewah_iterator_init(it, bitmap_git->trees);
+		break;
+
+	case OBJ_BLOB:
+		ewah_iterator_init(it, bitmap_git->blobs);
+		break;
+
+	case OBJ_TAG:
+		ewah_iterator_init(it, bitmap_git->tags);
+		break;
+
+	default:
+		BUG("object type %d not stored by bitmap type index", type);
+		break;
+	}
+}
+
 static void show_objects_for_type(
 	struct bitmap_index *bitmap_git,
-	struct ewah_bitmap *type_filter,
 	enum object_type object_type,
 	show_reachable_fn show_reach)
 {
-	size_t pos = 0, i = 0;
+	size_t i = 0;
 	uint32_t offset;
 
 	struct ewah_iterator it;
@@ -629,13 +670,15 @@ static void show_objects_for_type(
 
 	struct bitmap *objects = bitmap_git->result;
 
-	if (bitmap_git->reuse_objects == bitmap_git->pack->num_objects)
-		return;
-
-	ewah_iterator_init(&it, type_filter);
+	init_type_iterator(&it, bitmap_git, object_type);
 
-	while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
+	for (i = 0; i < objects->word_alloc &&
+			ewah_iterator_next(&filter, &it); i++) {
 		eword_t word = objects->words[i] & filter;
+		size_t pos = (i * BITS_IN_EWORD);
+
+		if (!word)
+			continue;
 
 		for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 			struct object_id oid;
@@ -647,20 +690,14 @@ static void show_objects_for_type(
 
 			offset += ewah_bit_ctz64(word >> offset);
 
-			if (pos + offset < bitmap_git->reuse_objects)
-				continue;
-
 			entry = &bitmap_git->pack->revindex[pos + offset];
-			nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
+			nth_packed_object_id(&oid, bitmap_git->pack, entry->nr);
 
 			if (bitmap_git->hashes)
 				hash = get_be32(bitmap_git->hashes + entry->nr);
 
 			show_reach(&oid, object_type, 0, hash, bitmap_git->pack, entry->offset);
 		}
-
-		pos += BITS_IN_EWORD;
-		i++;
 	}
 }
 
@@ -678,7 +715,179 @@ static int in_bitmapped_pack(struct bitmap_index *bitmap_git,
 	return 0;
 }
 
-struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
+static struct bitmap *find_tip_blobs(struct bitmap_index *bitmap_git,
+				     struct object_list *tip_objects)
+{
+	struct bitmap *result = bitmap_new();
+	struct object_list *p;
+
+	for (p = tip_objects; p; p = p->next) {
+		int pos;
+
+		if (p->item->type != OBJ_BLOB)
+			continue;
+
+		pos = bitmap_position(bitmap_git, &p->item->oid);
+		if (pos < 0)
+			continue;
+
+		bitmap_set(result, pos);
+	}
+
+	return result;
+}
+
+static void filter_bitmap_blob_none(struct bitmap_index *bitmap_git,
+				    struct object_list *tip_objects,
+				    struct bitmap *to_filter)
+{
+	struct eindex *eindex = &bitmap_git->ext_index;
+	struct bitmap *tips;
+	struct ewah_iterator it;
+	eword_t mask;
+	uint32_t i;
+
+	/*
+	 * The non-bitmap version of this filter never removes
+	 * blobs which the other side specifically asked for,
+	 * so we must match that behavior.
+	 */
+	tips = find_tip_blobs(bitmap_git, tip_objects);
+
+	/*
+	 * We can use the blob type-bitmap to work in whole words
+	 * for the objects that are actually in the bitmapped packfile.
+	 */
+	for (i = 0, init_type_iterator(&it, bitmap_git, OBJ_BLOB);
+	     i < to_filter->word_alloc && ewah_iterator_next(&mask, &it);
+	     i++) {
+		if (i < tips->word_alloc)
+			mask &= ~tips->words[i];
+		to_filter->words[i] &= ~mask;
+	}
+
+	/*
+	 * Clear any blobs that weren't in the packfile (and so would not have
+	 * been caught by the loop above. We'll have to check them
+	 * individually.
+	 */
+	for (i = 0; i < eindex->count; i++) {
+		uint32_t pos = i + bitmap_git->pack->num_objects;
+		if (eindex->objects[i]->type == OBJ_BLOB &&
+		    bitmap_get(to_filter, pos) &&
+		    !bitmap_get(tips, pos))
+			bitmap_unset(to_filter, pos);
+	}
+
+	bitmap_free(tips);
+}
+
+static unsigned long get_size_by_pos(struct bitmap_index *bitmap_git,
+				     uint32_t pos)
+{
+	struct packed_git *pack = bitmap_git->pack;
+	unsigned long size;
+	struct object_info oi = OBJECT_INFO_INIT;
+
+	oi.sizep = &size;
+
+	if (pos < pack->num_objects) {
+		struct revindex_entry *entry = &pack->revindex[pos];
+		if (packed_object_info(the_repository, pack,
+				       entry->offset, &oi) < 0) {
+			struct object_id oid;
+			nth_packed_object_id(&oid, pack, entry->nr);
+			die(_("unable to get size of %s"), oid_to_hex(&oid));
+		}
+	} else {
+		struct eindex *eindex = &bitmap_git->ext_index;
+		struct object *obj = eindex->objects[pos - pack->num_objects];
+		if (oid_object_info_extended(the_repository, &obj->oid, &oi, 0) < 0)
+			die(_("unable to get size of %s"), oid_to_hex(&obj->oid));
+	}
+
+	return size;
+}
+
+static void filter_bitmap_blob_limit(struct bitmap_index *bitmap_git,
+				     struct object_list *tip_objects,
+				     struct bitmap *to_filter,
+				     unsigned long limit)
+{
+	struct eindex *eindex = &bitmap_git->ext_index;
+	struct bitmap *tips;
+	struct ewah_iterator it;
+	eword_t mask;
+	uint32_t i;
+
+	tips = find_tip_blobs(bitmap_git, tip_objects);
+
+	for (i = 0, init_type_iterator(&it, bitmap_git, OBJ_BLOB);
+	     i < to_filter->word_alloc && ewah_iterator_next(&mask, &it);
+	     i++) {
+		eword_t word = to_filter->words[i] & mask;
+		unsigned offset;
+
+		for (offset = 0; offset < BITS_IN_EWORD; offset++) {
+			uint32_t pos;
+
+			if ((word >> offset) == 0)
+				break;
+			offset += ewah_bit_ctz64(word >> offset);
+			pos = i * BITS_IN_EWORD + offset;
+
+			if (!bitmap_get(tips, pos) &&
+			    get_size_by_pos(bitmap_git, pos) >= limit)
+				bitmap_unset(to_filter, pos);
+		}
+	}
+
+	for (i = 0; i < eindex->count; i++) {
+		uint32_t pos = i + bitmap_git->pack->num_objects;
+		if (eindex->objects[i]->type == OBJ_BLOB &&
+		    bitmap_get(to_filter, pos) &&
+		    !bitmap_get(tips, pos) &&
+		    get_size_by_pos(bitmap_git, pos) >= limit)
+			bitmap_unset(to_filter, pos);
+	}
+
+	bitmap_free(tips);
+}
+
+static int filter_bitmap(struct bitmap_index *bitmap_git,
+			 struct object_list *tip_objects,
+			 struct bitmap *to_filter,
+			 struct list_objects_filter_options *filter)
+{
+	if (!filter || filter->choice == LOFC_DISABLED)
+		return 0;
+
+	if (filter->choice == LOFC_BLOB_NONE) {
+		if (bitmap_git)
+			filter_bitmap_blob_none(bitmap_git, tip_objects,
+						to_filter);
+		return 0;
+	}
+
+	if (filter->choice == LOFC_BLOB_LIMIT) {
+		if (bitmap_git)
+			filter_bitmap_blob_limit(bitmap_git, tip_objects,
+						 to_filter,
+						 filter->blob_limit_value);
+		return 0;
+	}
+
+	/* filter choice not handled */
+	return -1;
+}
+
+static int can_filter_bitmap(struct list_objects_filter_options *filter)
+{
+	return !filter_bitmap(NULL, NULL, NULL, filter);
+}
+
+struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs,
+					 struct list_objects_filter_options *filter)
 {
 	unsigned int i;
 
@@ -688,9 +897,22 @@ struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
 	struct bitmap *wants_bitmap = NULL;
 	struct bitmap *haves_bitmap = NULL;
 
-	struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git));
+	struct bitmap_index *bitmap_git;
+
+	/*
+	 * We can't do pathspec limiting with bitmaps, because we don't know
+	 * which commits are associated with which object changes (let alone
+	 * even which objects are associated with which paths).
+	 */
+	if (revs->prune)
+		return NULL;
+
+	if (!can_filter_bitmap(filter))
+		return NULL;
+
 	/* try to open a bitmapped pack, but don't parse it yet
 	 * because we may not need to use it */
+	bitmap_git = xcalloc(1, sizeof(*bitmap_git));
 	if (open_pack_bitmap(revs->repo, bitmap_git) < 0)
 		goto cleanup;
 
@@ -708,9 +930,7 @@ struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
 			else
 				object_list_insert(object, &wants);
 
-			if (!tag->tagged)
-				die("bad tag");
-			object = parse_object_or_die(&tag->tagged->oid, NULL);
+			object = parse_object_or_die(get_tagged_oid(tag), NULL);
 		}
 
 		if (object->flags & UNINTERESTING)
@@ -759,93 +979,173 @@ struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
 	if (haves_bitmap)
 		bitmap_and_not(wants_bitmap, haves_bitmap);
 
+	filter_bitmap(bitmap_git, wants, wants_bitmap, filter);
+
 	bitmap_git->result = wants_bitmap;
 	bitmap_git->haves = haves_bitmap;
 
+	object_list_free(&wants);
+	object_list_free(&haves);
+
 	return bitmap_git;
 
 cleanup:
 	free_bitmap_index(bitmap_git);
+	object_list_free(&wants);
+	object_list_free(&haves);
 	return NULL;
 }
 
-int reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git,
-				       struct packed_git **packfile,
-				       uint32_t *entries,
-				       off_t *up_to)
+static void try_partial_reuse(struct bitmap_index *bitmap_git,
+			      size_t pos,
+			      struct bitmap *reuse,
+			      struct pack_window **w_curs)
 {
+	struct revindex_entry *revidx;
+	off_t offset;
+	enum object_type type;
+	unsigned long size;
+
+	if (pos >= bitmap_git->pack->num_objects)
+		return; /* not actually in the pack */
+
+	revidx = &bitmap_git->pack->revindex[pos];
+	offset = revidx->offset;
+	type = unpack_object_header(bitmap_git->pack, w_curs, &offset, &size);
+	if (type < 0)
+		return; /* broken packfile, punt */
+
+	if (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA) {
+		off_t base_offset;
+		int base_pos;
+
+		/*
+		 * Find the position of the base object so we can look it up
+		 * in our bitmaps. If we can't come up with an offset, or if
+		 * that offset is not in the revidx, the pack is corrupt.
+		 * There's nothing we can do, so just punt on this object,
+		 * and the normal slow path will complain about it in
+		 * more detail.
+		 */
+		base_offset = get_delta_base(bitmap_git->pack, w_curs,
+					     &offset, type, revidx->offset);
+		if (!base_offset)
+			return;
+		base_pos = find_revindex_position(bitmap_git->pack, base_offset);
+		if (base_pos < 0)
+			return;
+
+		/*
+		 * We assume delta dependencies always point backwards. This
+		 * lets us do a single pass, and is basically always true
+		 * due to the way OFS_DELTAs work. You would not typically
+		 * find REF_DELTA in a bitmapped pack, since we only bitmap
+		 * packs we write fresh, and OFS_DELTA is the default). But
+		 * let's double check to make sure the pack wasn't written with
+		 * odd parameters.
+		 */
+		if (base_pos >= pos)
+			return;
+
+		/*
+		 * And finally, if we're not sending the base as part of our
+		 * reuse chunk, then don't send this object either. The base
+		 * would come after us, along with other objects not
+		 * necessarily in the pack, which means we'd need to convert
+		 * to REF_DELTA on the fly. Better to just let the normal
+		 * object_entry code path handle it.
+		 */
+		if (!bitmap_get(reuse, base_pos))
+			return;
+	}
+
 	/*
-	 * Reuse the packfile content if we need more than
-	 * 90% of its objects
+	 * If we got here, then the object is OK to reuse. Mark it.
 	 */
-	static const double REUSE_PERCENT = 0.9;
+	bitmap_set(reuse, pos);
+}
 
+int reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git,
+				       struct packed_git **packfile_out,
+				       uint32_t *entries,
+				       struct bitmap **reuse_out)
+{
 	struct bitmap *result = bitmap_git->result;
-	uint32_t reuse_threshold;
-	uint32_t i, reuse_objects = 0;
+	struct bitmap *reuse;
+	struct pack_window *w_curs = NULL;
+	size_t i = 0;
+	uint32_t offset;
 
 	assert(result);
 
-	for (i = 0; i < result->word_alloc; ++i) {
-		if (result->words[i] != (eword_t)~0) {
-			reuse_objects += ewah_bit_ctz64(~result->words[i]);
-			break;
-		}
+	while (i < result->word_alloc && result->words[i] == (eword_t)~0)
+		i++;
 
-		reuse_objects += BITS_IN_EWORD;
-	}
+	/* Don't mark objects not in the packfile */
+	if (i > bitmap_git->pack->num_objects / BITS_IN_EWORD)
+		i = bitmap_git->pack->num_objects / BITS_IN_EWORD;
 
-#ifdef GIT_BITMAP_DEBUG
-	{
-		const unsigned char *sha1;
-		struct revindex_entry *entry;
+	reuse = bitmap_word_alloc(i);
+	memset(reuse->words, 0xFF, i * sizeof(eword_t));
 
-		entry = &bitmap_git->reverse_index->revindex[reuse_objects];
-		sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
+	for (; i < result->word_alloc; ++i) {
+		eword_t word = result->words[i];
+		size_t pos = (i * BITS_IN_EWORD);
 
-		fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
-			reuse_objects, result->words[i]);
-		fprintf(stderr, " %s\n", sha1_to_hex(sha1));
+		for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
+			if ((word >> offset) == 0)
+				break;
+
+			offset += ewah_bit_ctz64(word >> offset);
+			try_partial_reuse(bitmap_git, pos + offset, reuse, &w_curs);
+		}
 	}
-#endif
 
-	if (!reuse_objects)
-		return -1;
+	unuse_pack(&w_curs);
 
-	if (reuse_objects >= bitmap_git->pack->num_objects) {
-		bitmap_git->reuse_objects = *entries = bitmap_git->pack->num_objects;
-		*up_to = -1; /* reuse the full pack */
-		*packfile = bitmap_git->pack;
-		return 0;
+	*entries = bitmap_popcount(reuse);
+	if (!*entries) {
+		bitmap_free(reuse);
+		return -1;
 	}
 
-	reuse_threshold = bitmap_popcount(bitmap_git->result) * REUSE_PERCENT;
+	/*
+	 * Drop any reused objects from the result, since they will not
+	 * need to be handled separately.
+	 */
+	bitmap_and_not(result, reuse);
+	*packfile_out = bitmap_git->pack;
+	*reuse_out = reuse;
+	return 0;
+}
 
-	if (reuse_objects < reuse_threshold)
-		return -1;
+int bitmap_walk_contains(struct bitmap_index *bitmap_git,
+			 struct bitmap *bitmap, const struct object_id *oid)
+{
+	int idx;
 
-	bitmap_git->reuse_objects = *entries = reuse_objects;
-	*up_to = bitmap_git->pack->revindex[reuse_objects].offset;
-	*packfile = bitmap_git->pack;
+	if (!bitmap)
+		return 0;
 
-	return 0;
+	idx = bitmap_position(bitmap_git, oid);
+	return idx >= 0 && bitmap_get(bitmap, idx);
 }
 
 void traverse_bitmap_commit_list(struct bitmap_index *bitmap_git,
+				 struct rev_info *revs,
 				 show_reachable_fn show_reachable)
 {
 	assert(bitmap_git->result);
 
-	show_objects_for_type(bitmap_git, bitmap_git->commits,
-		OBJ_COMMIT, show_reachable);
-	show_objects_for_type(bitmap_git, bitmap_git->trees,
-		OBJ_TREE, show_reachable);
-	show_objects_for_type(bitmap_git, bitmap_git->blobs,
-		OBJ_BLOB, show_reachable);
-	show_objects_for_type(bitmap_git, bitmap_git->tags,
-		OBJ_TAG, show_reachable);
+	show_objects_for_type(bitmap_git, OBJ_COMMIT, show_reachable);
+	if (revs->tree_objects)
+		show_objects_for_type(bitmap_git, OBJ_TREE, show_reachable);
+	if (revs->blob_objects)
+		show_objects_for_type(bitmap_git, OBJ_BLOB, show_reachable);
+	if (revs->tag_objects)
+		show_objects_for_type(bitmap_git, OBJ_TAG, show_reachable);
 
-	show_extended_objects(bitmap_git, show_reachable);
+	show_extended_objects(bitmap_git, revs, show_reachable);
 }
 
 static uint32_t count_object_type(struct bitmap_index *bitmap_git,
@@ -858,26 +1158,7 @@ static uint32_t count_object_type(struct bitmap_index *bitmap_git,
 	struct ewah_iterator it;
 	eword_t filter;
 
-	switch (type) {
-	case OBJ_COMMIT:
-		ewah_iterator_init(&it, bitmap_git->commits);
-		break;
-
-	case OBJ_TREE:
-		ewah_iterator_init(&it, bitmap_git->trees);
-		break;
-
-	case OBJ_BLOB:
-		ewah_iterator_init(&it, bitmap_git->blobs);
-		break;
-
-	case OBJ_TAG:
-		ewah_iterator_init(&it, bitmap_git->tags);
-		break;
-
-	default:
-		return 0;
-	}
+	init_type_iterator(&it, bitmap_git, type);
 
 	while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 		eword_t word = objects->words[i++] & filter;
@@ -925,7 +1206,7 @@ static void test_show_object(struct object *object, const char *name,
 	struct bitmap_test_data *tdata = data;
 	int bitmap_pos;
 
-	bitmap_pos = bitmap_position(tdata->bitmap_git, object->oid.hash);
+	bitmap_pos = bitmap_position(tdata->bitmap_git, &object->oid);
 	if (bitmap_pos < 0)
 		die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 
@@ -939,7 +1220,7 @@ static void test_show_commit(struct commit *commit, void *data)
 	int bitmap_pos;
 
 	bitmap_pos = bitmap_position(tdata->bitmap_git,
-				     commit->object.oid.hash);
+				     &commit->object.oid);
 	if (bitmap_pos < 0)
 		die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 
@@ -966,7 +1247,7 @@ void test_bitmap_walk(struct rev_info *revs)
 		bitmap_git->version, bitmap_git->entry_count);
 
 	root = revs->pending.objects[0].item;
-	pos = kh_get_sha1(bitmap_git->bitmaps, root->oid.hash);
+	pos = kh_get_oid_map(bitmap_git->bitmaps, root->oid);
 
 	if (pos < kh_end(bitmap_git->bitmaps)) {
 		struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
@@ -1040,7 +1321,7 @@ static int rebuild_bitmap(uint32_t *reposition,
 
 int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 			     struct packing_data *mapping,
-			     khash_sha1 *reused_bitmaps,
+			     kh_oid_map_t *reused_bitmaps,
 			     int show_progress)
 {
 	uint32_t i, num_objects;
@@ -1056,13 +1337,13 @@ int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 	reposition = xcalloc(num_objects, sizeof(uint32_t));
 
 	for (i = 0; i < num_objects; ++i) {
-		const unsigned char *sha1;
+		struct object_id oid;
 		struct revindex_entry *entry;
 		struct object_entry *oe;
 
 		entry = &bitmap_git->pack->revindex[i];
-		sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
-		oe = packlist_find(mapping, sha1, NULL);
+		nth_packed_object_id(&oid, bitmap_git->pack, entry->nr);
+		oe = packlist_find(mapping, &oid);
 
 		if (oe)
 			reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
@@ -1079,9 +1360,9 @@ int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 			if (!rebuild_bitmap(reposition,
 					    lookup_stored_bitmap(stored),
 					    rebuild)) {
-				hash_pos = kh_put_sha1(reused_bitmaps,
-						       stored->sha1,
-						       &hash_ret);
+				hash_pos = kh_put_oid_map(reused_bitmaps,
+							  stored->oid,
+							  &hash_ret);
 				kh_value(reused_bitmaps, hash_pos) =
 					bitmap_to_ewah(rebuild);
 			}
@@ -1108,7 +1389,7 @@ void free_bitmap_index(struct bitmap_index *b)
 	ewah_pool_free(b->trees);
 	ewah_pool_free(b->blobs);
 	ewah_pool_free(b->tags);
-	kh_destroy_sha1(b->bitmaps);
+	kh_destroy_oid_map(b->bitmaps);
 	free(b->ext_index.objects);
 	free(b->ext_index.hashes);
 	bitmap_free(b->result);
@@ -1116,19 +1397,9 @@ void free_bitmap_index(struct bitmap_index *b)
 	free(b);
 }
 
-int bitmap_has_sha1_in_uninteresting(struct bitmap_index *bitmap_git,
-				     const unsigned char *sha1)
+int bitmap_has_oid_in_uninteresting(struct bitmap_index *bitmap_git,
+				    const struct object_id *oid)
 {
-	int pos;
-
-	if (!bitmap_git)
-		return 0; /* no bitmap loaded */
-	if (!bitmap_git->haves)
-		return 0; /* walk had no "haves" */
-
-	pos = bitmap_position_packfile(bitmap_git, sha1);
-	if (pos < 0)
-		return 0;
-
-	return bitmap_get(bitmap_git->haves, pos);
+	return bitmap_git &&
+		bitmap_walk_contains(bitmap_git, bitmap_git->haves, oid);
 }