pack-bitmap: introduce function to check whether a pack is bitmapped

Introduce a function that allows us to verify whether a pack is
bitmapped or not. This functionality will be used in a subsequent
commit.

Helped-by: Taylor Blau <[email protected]>
Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

pack-bitmap.c

@@ -745,6 +745,21 @@ struct bitmap_index *prepare_midx_bitmap_git(struct multi_pack_index *midx)
 	return NULL;
 }
 
+int bitmap_index_contains_pack(struct bitmap_index *bitmap, struct packed_git *pack)
+{
+	for (; bitmap; bitmap = bitmap->base) {
+		if (bitmap_is_midx(bitmap)) {
+			for (size_t i = 0; i < bitmap->midx->num_packs; i++)
+				if (bitmap->midx->packs[i] == pack)
+					return 1;
+		} else if (bitmap->pack == pack) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 struct include_data {
 	struct bitmap_index *bitmap_git;
 	struct bitmap *base;

pack-bitmap.h

@@ -67,6 +67,13 @@ struct bitmapped_pack {
 
 struct bitmap_index *prepare_bitmap_git(struct repository *r);
 struct bitmap_index *prepare_midx_bitmap_git(struct multi_pack_index *midx);
+
+/*
+ * Given a bitmap index, determine whether it contains the pack either directly
+ * or via the multi-pack-index.
+ */
+int bitmap_index_contains_pack(struct bitmap_index *bitmap, struct packed_git *pack);
+
 void count_bitmap_commit_list(struct bitmap_index *, uint32_t *commits,
 			      uint32_t *trees, uint32_t *blobs, uint32_t *tags);
 void traverse_bitmap_commit_list(struct bitmap_index *,