From: Stefan Beller <sbeller@google.com>
Date: Wed, 26 Apr 2017 23:01:27 GMT
Subject: Re: [PATCH 35/53] Convert the verify_pack callback to struct object_id
Message-ID: <CAGZ79kYhaX=tXM2aymFDkfU23E8=GzjgGbwQsynt1LWdLzxQQw@mail.gmail.com>
In-Reply-To: <20170423213453.253425-36-sandals@crustytoothpaste.net>

On Sun, Apr 23, 2017 at 2:34 PM, brian m. carlson
<sandals@crustytoothpaste.net> wrote:
> Make the verify_pack_callback take a pointer to struct object_id.  Use a
> struct object_id to hold the pack checksum, even though it is not
> strictly an object ID.  Doing so ensures resilience against future hash
> size changes, and allows us to remove hard-coded assumptions about how
> big the buffer needs to be.
>
> Also, use a union to convert the pointer from nth_packed_object_sha1 to
> to a pointer to struct object_id.  This behavior is compatible with GCC
> and clang and explicitly sanctioned by C11.  The alternatives are to
> just perform a cast, which would run afoul of strict aliasing rules, but
> should just work, and changing the pointer into an instance of struct
> object_id and copying the value.  The latter operation could seriously
> bloat memory usage on fsck, which already uses a lot of memory on some
> repositories.
>
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---

Up to here *excluding* this one, looking good.
This one may need review by an expert specialized in weird corner cases,
which I am not, yet. ;)

Thanks,
Stefan