Re: [PATCH 2/2] unpack_entry: do not die when we fail to apply a delta

Jeff King [off-list ref] writes:

 test_expect_success \
+    'corruption of delta base reference pointing to wrong object' \
+    'create_new_pack --delta-base-offset &&
+     git prune-packed &&
+     printf "\220\033" | do_corrupt_object $blob_3 2 &&

Interesting.  You cheated in a different way with a hardcoded
offset, instead of hardcoded knowledge of where the object name
is stored in binary in the .idx file ;-)

+     git cat-file blob $blob_1 >/dev/null &&
+     git cat-file blob $blob_2 >/dev/null &&
+     test_must_fail git cat-file blob $blob_3 >/dev/null'
+
+test_expect_success \
+    '... but having a loose copy allows for full recovery' \
+    'mv ${pack}.idx tmp &&
+     git hash-object -t blob -w file_3 &&
+     mv tmp ${pack}.idx &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'
+
+test_expect_success \
+    '... and then a repack "clears" the corruption' \
+    'do_repack --delta-base-offset --no-reuse-delta &&
+     git prune-packed &&
+     git verify-pack ${pack}.pack &&
+     git cat-file blob $blob_1 > /dev/null &&
+     git cat-file blob $blob_2 > /dev/null &&
+     git cat-file blob $blob_3 > /dev/null'

Nice.  Will replace the one I queued yesterday with these two patches.

+test_expect_success \
     'corrupting header to have too small output buffer fails unpack' \
     'create_new_pack &&
      git prune-packed &&

On Fri, Jun 14, 2013 at 02:59:00PM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

 test_expect_success \
+    'corruption of delta base reference pointing to wrong object' \
+    'create_new_pack --delta-base-offset &&
+     git prune-packed &&
+     printf "\220\033" | do_corrupt_object $blob_3 2 &&

Interesting.  You cheated in a different way with a hardcoded
offset, instead of hardcoded knowledge of where the object name
is stored in binary in the .idx file ;-)

Yes. We could get it with:

  git show-index <"$pack.idx" |
  cut -d' ' -f1 |
  perl -e '
    @pos = map { chomp; $_ } <>;
    my $ofs = $pos[2] - $pos[0];

    my @bin;
    unshift @bin, $ofs & 127;
    while ($ofs >>= 7) {
      $ofs--;
      unshift @bin, 128 | ($ofs & 127);
    }

    binmode STDOUT;
    print chr for @bin;
  '

if that's not too ugly. Maybe the REF_DELTA one is less ugly, then, as
it would not need to do the packed offset encoding, but just convert
$blob1 from hex into binary.

-Peff