packfile: extend `is_delta` field to allow for "unknown" state

The `struct object_info::u::packed::is_delta` field determines whether
or not a specific object is stored as a delta. It only stores whether or
not the object is stored as delta, so it is treated as a boolean value.

This boolean is insufficient though: when reading a packed object via
`packfile_store_read_object_info()` we know to skip parsing the actual
object when the user didn't request any object-specific data. In that
case we won't read the object itself, but will only look up its position
in the packfile. Consequently, we do not know whether it is a delta or
not.

This isn't really an issue right now, as the check for an empty request
is broken. But a subsequent commit will fix it, and once we do we will
have the need to also represent an "unknown" delta state.

Prepare for this change by introducing a new enum that encodes the
object type. We don't use the "unknown" state just yet, but will start
to do so in a subsequent commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/odb.h b/odb.h
index 73b0b87ad5..afae5e5c01 100644
--- a/odb.h
+++ b/odb.h
@@ -343,7 +343,12 @@ struct object_info {
 		struct {
 			struct packed_git *pack;
 			off_t offset;
-			unsigned int is_delta;
+			enum packed_object_type {
+				PACKED_OBJECT_TYPE_UNKNOWN,
+				PACKED_OBJECT_TYPE_FULL,
+				PACKED_OBJECT_TYPE_OFS_DELTA,
+				PACKED_OBJECT_TYPE_REF_DELTA,
+			} type;
 		} packed;
 	} u;
 };