packed_object_info: hoist delta type resolution to helper

To calculate the type of a packed object, we must walk down
its delta chain until we hit a true base object with a real
type. Most of the code in packed_object_info is for handling
this case.

Let's hoist it out into a separate helper function, which
will make it easier to make the type-lookup optional in the
future (and keep our indentation level sane).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_file.c

@@ -1710,9 +1710,75 @@ static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
 	return type;
 }
 
-
 #define POI_STACK_PREALLOC 64
 
+static enum object_type packed_to_object_type(struct packed_git *p,
+					      off_t obj_offset,
+					      enum object_type type,
+					      struct pack_window **w_curs,
+					      off_t curpos)
+{
+	off_t small_poi_stack[POI_STACK_PREALLOC];
+	off_t *poi_stack = small_poi_stack;
+	int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
+
+	while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
+		off_t base_offset;
+		unsigned long size;
+		/* Push the object we're going to leave behind */
+		if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
+			poi_stack_alloc = alloc_nr(poi_stack_nr);
+			poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
+			memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
+		} else {
+			ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
+		}
+		poi_stack[poi_stack_nr++] = obj_offset;
+		/* If parsing the base offset fails, just unwind */
+		base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
+		if (!base_offset)
+			goto unwind;
+		curpos = obj_offset = base_offset;
+		type = unpack_object_header(p, w_curs, &curpos, &size);
+		if (type <= OBJ_NONE) {
+			/* If getting the base itself fails, we first
+			 * retry the base, otherwise unwind */
+			type = retry_bad_packed_offset(p, base_offset);
+			if (type > OBJ_NONE)
+				goto out;
+			goto unwind;
+		}
+	}
+
+	switch (type) {
+	case OBJ_BAD:
+	case OBJ_COMMIT:
+	case OBJ_TREE:
+	case OBJ_BLOB:
+	case OBJ_TAG:
+		break;
+	default:
+		error("unknown object type %i at offset %"PRIuMAX" in %s",
+		      type, (uintmax_t)obj_offset, p->pack_name);
+		type = OBJ_BAD;
+	}
+
+out:
+	if (poi_stack != small_poi_stack)
+		free(poi_stack);
+	return type;
+
+unwind:
+	while (poi_stack_nr) {
+		obj_offset = poi_stack[--poi_stack_nr];
+		type = retry_bad_packed_offset(p, obj_offset);
+		if (type > OBJ_NONE)
+			goto out;
+	}
+	type = OBJ_BAD;
+	goto out;
+}
+
 static int packed_object_info(struct packed_git *p, off_t obj_offset,
 			      unsigned long *sizep, int *rtype,
 			      unsigned long *disk_sizep)
@@ -1721,9 +1787,6 @@ static int packed_object_info(struct packed_git *p, off_t obj_offset,
 	unsigned long size;
 	off_t curpos = obj_offset;
 	enum object_type type;
-	off_t small_poi_stack[POI_STACK_PREALLOC];
-	off_t *poi_stack = small_poi_stack;
-	int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
 
 	type = unpack_object_header(p, &w_curs, &curpos, &size);
 
@@ -1754,61 +1817,11 @@ static int packed_object_info(struct packed_git *p, off_t obj_offset,
 		*disk_sizep = revidx[1].offset - obj_offset;
 	}
 
-	while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
+	type = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
-		off_t base_offset;
-		/* Push the object we're going to leave behind */
-		if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
-			poi_stack_alloc = alloc_nr(poi_stack_nr);
-			poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
-			memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
-		} else {
-			ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
-		}
-		poi_stack[poi_stack_nr++] = obj_offset;
-		/* If parsing the base offset fails, just unwind */
-		base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
-		if (!base_offset)
-			goto unwind;
-		curpos = obj_offset = base_offset;
-		type = unpack_object_header(p, &w_curs, &curpos, &size);
-		if (type <= OBJ_NONE) {
-			/* If getting the base itself fails, we first
-			 * retry the base, otherwise unwind */
-			type = retry_bad_packed_offset(p, base_offset);
-			if (type > OBJ_NONE)
-				goto out;
-			goto unwind;
-		}
-	}
-
-	switch (type) {
-	case OBJ_BAD:
-	case OBJ_COMMIT:
-	case OBJ_TREE:
-	case OBJ_BLOB:
-	case OBJ_TAG:
-		break;
-	default:
-		error("unknown object type %i at offset %"PRIuMAX" in %s",
-		      type, (uintmax_t)obj_offset, p->pack_name);
-		type = OBJ_BAD;
-	}
 
 out:
-	if (poi_stack != small_poi_stack)
-		free(poi_stack);
 	unuse_pack(&w_curs);
 	return type;
-
-unwind:
-	while (poi_stack_nr) {
-		obj_offset = poi_stack[--poi_stack_nr];
-		type = retry_bad_packed_offset(p, obj_offset);
-		if (type > OBJ_NONE)
-			goto out;
-	}
-	type = OBJ_BAD;
-	goto out;
 }
 
 static void *unpack_compressed_entry(struct packed_git *p,