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, 18 insertions, 0 deletions

diff --git a/t/t5302-pack-index.sh b/t/t5302-pack-index.sh
index b34ea93a80..7c5fa03920 100755
--- a/t/t5302-pack-index.sh
+++ b/t/t5302-pack-index.sh
@@ -65,6 +65,14 @@ test_expect_success \
     'cmp "test-1-${pack1}.idx" "1.idx" &&
      cmp "test-2-${pack2}.idx" "2.idx"'
 
+test_expect_success 'index-pack --verify on index version 1' '
+	git index-pack --verify "test-1-${pack1}.pack"
+'
+
+test_expect_success 'index-pack --verify on index version 2' '
+	git index-pack --verify "test-2-${pack2}.pack"
+'
+
 test_expect_success \
     'index v2: force some 64-bit offsets with pack-objects' \
     'pack3=$(git pack-objects --index-version=2,0x40000 test-3 <obj-list)'
@@ -93,6 +101,16 @@ test_expect_success OFF64_T \
     '64-bit offsets: index-pack result should match pack-objects one' \
     'cmp "test-3-${pack3}.idx" "3.idx"'
 
+test_expect_success OFF64_T 'index-pack --verify on 64-bit offset v2 (cheat)' '
+	# This cheats by knowing which lower offset should still be encoded
+	# in 64-bit representation.
+	git index-pack --verify --index-version=2,0x40000 "test-3-${pack3}.pack"
+'
+
+test_expect_failure OFF64_T 'index-pack --verify on 64-bit offset v2' '
+	git index-pack --verify "test-3-${pack3}.pack"
+'
+
 # returns the object number for given object in given pack index
 index_obj_nr()
 {