Re: [PATCH 05/23] midx: write header information to lockfile

>
> On 6/12/2018 11:00 AM, Duy Nguyen wrote:
> > On Thu, Jun 7, 2018 at 7:01 PM Derrick Stolee <stolee@gmail.com> wrote:
> >> diff --git a/midx.c b/midx.c
> >> index 616af66b13..3e55422a21 100644
> >> --- a/midx.c
> >> +++ b/midx.c
> >> @@ -1,9 +1,62 @@
> >>   #include "git-compat-util.h"
> >>   #include "cache.h"
> >>   #include "dir.h"
> >> +#include "csum-file.h"
> >> +#include "lockfile.h"
> >>   #include "midx.h"
> >>
> >> +#define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
> >> +#define MIDX_VERSION 1
> >> +#define MIDX_HASH_VERSION 1 /* SHA-1 */
> > ...
> >> +static size_t write_midx_header(struct hashfile *f,
> >> +                               unsigned char num_chunks,
> >> +                               uint32_t num_packs)
> >> +{
> >> +       char byte_values[4];
> >> +       hashwrite_be32(f, MIDX_SIGNATURE);
> >> +       byte_values[0] = MIDX_VERSION;
> >> +       byte_values[1] = MIDX_HASH_VERSION;
> > Quoting from "State of NewHash work, future directions, and discussion" [1]
> >
> > * If you need to serialize an algorithm identifier into your data
> >    format, use the format_id field of struct git_hash_algo.  It's
> >    designed specifically for that purpose.
> >
> > [1] https://public-inbox.org/git/20180612024252.GA141166@aiede.svl.corp.google.com/T/#m5fdd09dcaf31266c45343fb6c0beaaa3e928bc60
>
> Thanks! I'll also use the_hash_algo->rawsz to infer the length of the
> hash function.