Re: pack corruption post-mortem

> On Sat, 19 Oct 2013, Duy Nguyen wrote:
>
>> On Wed, Oct 16, 2013 at 3:34 PM, Jeff King <peff@peff.net> wrote:
>> > I was recently presented with a repository with a corrupted packfile,
>> > and was asked if the data was recoverable. This post-mortem describes
>> > the steps I took to investigate and fix the problem. I thought others
>> > might find the process interesting, and it might help somebody in the
>> > same situation.
>> >
>> > I started with an fsck, which found a problem with exactly one object
>> > (I've used $pack and $obj below to keep the output readable, and also
>> > because I'll refer to them later):
>> >
>> >     $ git fsck
>> >     error: $pack SHA1 checksum mismatch
>> >     error: index CRC mismatch for object $obj from $pack at offset 51653873
>> >     error: inflate: data stream error (incorrect data check)
>> >     error: cannot unpack $obj from $pack at offset 51653873
>>
>> I wonder if we should protect the sha-1 and pathname tables in packv4
>> with CRC too. A bit flipped in there could cause stream of corrupt
>> objects and make it hard to pinpoint the corrupt location..
>
> It turns out that we already have this covered.
>
> The SHA1 used in the name of the pack file is actually the SHA1 checksum
> of the SHA1 table.