pack: move unpack_object_header()

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/packfile.c b/packfile.c
index 9e0bbf5a0e..d4a78b1ac9 100644
--- a/packfile.c
+++ b/packfile.c
@@ -949,3 +949,29 @@ unsigned long get_size_from_delta(struct packed_git *p,
 	/* Read the result size */
 	return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 }
+
+int unpack_object_header(struct packed_git *p,
+			 struct pack_window **w_curs,
+			 off_t *curpos,
+			 unsigned long *sizep)
+{
+	unsigned char *base;
+	unsigned long left;
+	unsigned long used;
+	enum object_type type;
+
+	/* use_pack() assures us we have [base, base + 20) available
+	 * as a range that we can look at.  (Its actually the hash
+	 * size that is assured.)  With our object header encoding
+	 * the maximum deflated object size is 2^137, which is just
+	 * insane, so we know won't exceed what we have been given.
+	 */
+	base = use_pack(p, w_curs, *curpos, &left);
+	used = unpack_object_header_buffer(base, left, &type, sizep);
+	if (!used) {
+		type = OBJ_BAD;
+	} else
+		*curpos += used;
+
+	return type;
+}