fix unimplemented packed_object_info_detail() features

Since commit eb32d236df, there was a TODO
comment in packed_object_info_detail() about the SHA1 of base object to
OBJ_OFS_DELTA objects.  So here it is at last.

While at it, providing the actual storage size information as well is now
trivial.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pack-check.c

@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "pack.h"
+#include "pack-revindex.h"
 
 struct idx_entry
 {
@@ -101,8 +102,10 @@ static int verify_packfile(struct packed_git *p,
 static void show_pack_info(struct packed_git *p)
 {
 	uint32_t nr_objects, i, chain_histogram[MAX_CHAIN+1];
+
 	nr_objects = p->num_objects;
 	memset(chain_histogram, 0, sizeof(chain_histogram));
+	init_pack_revindex();
 
 	for (i = 0; i < nr_objects; i++) {
 		const unsigned char *sha1;

sha1_file.c

@@ -14,6 +14,7 @@
 #include "tag.h"
 #include "tree.h"
 #include "refs.h"
+#include "pack-revindex.h"
 
 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
@@ -1367,11 +1368,15 @@ const char *packed_object_info_detail(struct packed_git *p,
 	unsigned long dummy;
 	unsigned char *next_sha1;
 	enum object_type type;
+	struct revindex_entry *revidx;
 
 	*delta_chain_length = 0;
 	curpos = obj_offset;
 	type = unpack_object_header(p, &w_curs, &curpos, size);
 
+	revidx = find_pack_revindex(p, obj_offset);
+	*store_size = revidx[1].offset - obj_offset;
+
 	for (;;) {
 		switch (type) {
 		default:
@@ -1381,14 +1386,13 @@ const char *packed_object_info_detail(struct packed_git *p,
 		case OBJ_TREE:
 		case OBJ_BLOB:
 		case OBJ_TAG:
-			*store_size = 0; /* notyet */
 			unuse_pack(&w_curs);
 			return typename(type);
 		case OBJ_OFS_DELTA:
 			obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
 			if (*delta_chain_length == 0) {
-				/* TODO: find base_sha1 as pointed by curpos */
-				hashclr(base_sha1);
+				revidx = find_pack_revindex(p, obj_offset);
+				hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
 			}
 			break;
 		case OBJ_REF_DELTA: