[PATCH 02/11] sha1_object_info_extended(): expose a bit more info

[Junio C Hamano <gitster@pobox.com>]

The original interface for sha1_object_info() takes an object name and
gives back a type and its size (the latter is given only when it was
asked).  The new interface wraps its implementation and exposes a bit
more pieces of information that the interface used to discard, namely:

 - where the object is stored (loose? cached? packed?)
 - if packed, where in which packfile?

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 cache.h     |   29 +++++++++++++++++++++++++++++
 sha1_file.c |   46 +++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 68 insertions(+), 7 deletions(-)

diff --git a/cache.h b/cache.h
index cdb5112..dfd2d61 100644
--- a/cache.h
+++ b/cache.h
@@ -1022,6 +1022,35 @@ extern unsigned long unpack_object_header_buffer(const unsigned char *buf, unsig
 extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
 extern int packed_object_info_detail(struct packed_git *, off_t, unsigned long *, unsigned long *, unsigned int *, unsigned char *);
 
+struct object_info {
+	/* Request */
+	unsigned long *sizep;
+	int want_deltainfo;
+
+	/* Response */
+	enum {
+		OI_CACHED,
+		OI_LOOSE,
+		OI_PACKED
+	} whence;
+	union {
+		/*
+		 * struct {
+		 * 	... Nothing to expose in this case
+		 * } cached;
+		 * struct {
+		 * 	... Nothing to expose in this case
+		 * } loose;
+		 */
+		struct {
+			off_t offset;
+			unsigned int delta;
+			struct packed_git *pack;
+		} packed;
+	} u;
+};
+extern int sha1_object_info_extended(const unsigned char *, struct object_info *);
+
 /* Dumb servers support */
 extern int update_server_info(int);
 
diff --git a/sha1_file.c b/sha1_file.c
index 4f96eb1..9b16cd8 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2093,7 +2093,8 @@ static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *size
 	return status;
 }
 
-int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
+/* returns enum object_type or negative */
+int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
 {
 	struct cached_object *co;
 	struct pack_entry e;
@@ -2101,16 +2102,19 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 
 	co = find_cached_object(sha1);
 	if (co) {
-		if (sizep)
-			*sizep = co->size;
+		if (oi->sizep)
+			*(oi->sizep) = co->size;
+		oi->whence = OI_CACHED;
 		return co->type;
 	}
 
 	if (!find_pack_entry(sha1, &e)) {
 		/* Most likely it's a loose object. */
-		status = sha1_loose_object_info(sha1, sizep);
-		if (status >= 0)
+		status = sha1_loose_object_info(sha1, oi->sizep);
+		if (status >= 0) {
+			oi->whence = OI_LOOSE;
 			return status;
+		}
 
 		/* Not a loose object; someone else may have just packed it. */
 		reprepare_packed_git();
@@ -2118,15 +2122,43 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 			return status;
 	}
 
-	status = packed_object_info(e.p, e.offset, sizep);
+	if (!oi->want_deltainfo) {
+		status = packed_object_info(e.p, e.offset, oi->sizep);
+	} else {
+		unsigned long size, store_size;
+		unsigned int delta_chain_length;
+		unsigned char base_sha1[20];
+		status = packed_object_info_detail(e.p, e.offset,
+						   &size, &store_size,
+						   &delta_chain_length,
+						   base_sha1);
+		if (0 <= status) {
+			if (oi->sizep)
+				*oi->sizep = size;
+			oi->u.packed.delta = delta_chain_length;
+		}
+	}
 	if (status < 0) {
 		mark_bad_packed_object(e.p, sha1);
-		status = sha1_object_info(sha1, sizep);
+		status = sha1_object_info_extended(sha1, oi);
+	} else {
+		oi->whence = OI_PACKED;
+		oi->u.packed.offset = e.offset;
+		oi->u.packed.pack = e.p;
 	}
 
 	return status;
 }
 
+int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
+{
+	struct object_info oi;
+
+	oi.sizep = sizep;
+	oi.want_deltainfo = 0;
+	return sha1_object_info_extended(sha1, &oi);
+}
+
 static void *read_packed_sha1(const unsigned char *sha1,
 			      enum object_type *type, unsigned long *size)
 {
-- 
1.7.5.1.365.g32b65