index-pack: --verify

Given an existing .pack file and the .idx file that describes it,
this new mode of operation reads and re-index the packfile and makes
sure the existing .idx file matches the result byte-for-byte.

All the objects in the .pack file are validated during this operation as
well.  Unlike verify-pack, which visits each object described in the .idx
file in the SHA-1 order, index-pack efficiently exploits the delta-chain
to avoid rebuilding the objects that are used as the base of deltified
objects over and over again while validating the objects, resulting in
much quicker verification of the .pack file and its .idx file.

This version however cannot verify a .pack/.idx pair with a handcrafted v2
index that uses 64-bit offset representation for offsets that would fit
within 31-bit. You can create such an .idx file by giving a custom offset
to --index-version option to the command.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/pack.h b/pack.h
index 953f57e8b2..dddafdd160 100644
--- a/pack.h
+++ b/pack.h
@@ -35,6 +35,10 @@ struct pack_header {
 #define PACK_IDX_SIGNATURE 0xff744f63	/* "\377tOc" */
 
 struct pack_idx_option {
+	unsigned flags;
+	/* flag bits */
+#define WRITE_IDX_VERIFY 01
+
 	uint32_t version;
 	uint32_t off32_limit;
 };