object-file API: add a format_object_header() function

Add a convenience function to wrap the xsnprintf() command that
generates loose object headers. This code was copy/pasted in various
parts of the codebase, let's define it in one place and re-use it from
there.

All except one caller of it had a valid "enum object_type" for us,
it's only write_object_file_prepare() which might need to deal with
"git hash-object --literally" and a potential garbage type. Let's have
the primary API use an "enum object_type", and define a *_literally()
function that can take an arbitrary "const char *" for the type.

See [1] for the discussion that prompted this patch, i.e. new code in
object-file.c that wanted to copy/paste the xsnprintf() invocation.

In the case of fast-import.c the callers unfortunately need to cast
back & forth between "unsigned char *" and "char *", since
format_object_header() ad encode_in_pack_object_header() take
different signedness.

1. https://lore.kernel.org/git/211213.86bl1l9bfz.gmgdl@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ævar Arnfjörð Bjarmason
2022-02-05 00:48:25 +01:00
committed by Junio C Hamano
parent 63e05f9056
commit b04cdea46c
6 changed files with 35 additions and 11 deletions

View File

@ -220,8 +220,8 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
if (seekback == (off_t) -1)
return error("cannot find the current offset");
header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX,
type_name(type), (uintmax_t)size) + 1;
header_len = format_object_header((char *)obuf, sizeof(obuf),
type, size);
the_hash_algo->init_fn(&ctx);
the_hash_algo->update_fn(&ctx, obuf, header_len);