[PATCH v2 0/2] upload-pack: don't ACK non-commits repeatedly

Hi,

this patch series addresses an issue with storing duplicate object IDs sent by the client in git-upload-pack(1). If the client sends repeated "have" lines for an object ID that doesn't refer to a commit, then we end up storing that object ID repeatedly in the `have_obj` array. This leads to sending out repeated "ACK"s for the same object.

The series applies on top of "maint" at c44beea485 (Git 2.51, 2025-08-17).

Changes in v2:
  - Change ordering so that we always mark parents of already-seen
    commits as `THEY_HAVE`. The first version was _probably_ fine, but
    I don't feel too comfortable with a "probably".
  - Link to v1: https://lore.kernel.org/r/20250903-b4-pks-upload-pack-repeated-non-commit-acks-v1-0-4e019af4dddc@pks.im

Thanks!

Patrick

---
Patrick Steinhardt (2):
      t5530: modernize tests
      upload-pack: don't ACK non-commits repeatedly in protocol v2

 t/t5530-upload-pack-error.sh | 68 +++++++++++++++++++++++++++-----------------
 upload-pack.c                | 19 ++++++-------
 2 files changed, 51 insertions(+), 36 deletions(-)

Range-diff versus v1:

1:  a42d231813 = 1:  26ecbcf460 t5530: modernize tests
2:  1544160961 ! 2:  11e32bf5e6 upload-pack: don't ACK non-commits repeatedly in protocol v2
    @@ upload-pack.c: static void create_pack_file(struct upload_pack_data *pack_data,
      
      	if (!o)
      		die("oops (%s)", oid_to_hex(oid));
    -+
    -+	if (o->flags & THEY_HAVE)
    -+		return 0;
    -+	o->flags |= THEY_HAVE;
     +
      	if (o->type == OBJ_COMMIT) {
      		struct commit_list *parents;
    @@ upload-pack.c: static int do_got_oid(struct upload_pack_data *data, const struct
     -	}
     -	return 0;
     +
    ++	if (o->flags & THEY_HAVE)
    ++		return 0;
    ++	o->flags |= THEY_HAVE;
    ++
     +	add_object_array(o, NULL, &data->have_obj);
     +	return 1;
      }

--- base-commit: c44beea485f0f2feaf460e2ac87fdd5608d63cf0 change-id: 20250903-b4-pks-upload-pack-repeated-non-commit-acks-49b363e1d0e1