Enforce OAPV_MAX_NUM_META_PAYLOADS limit in oapvm_set()

[fkyslov]

Summary

Enforces the maximum metadata payload count in oapvm_set() (src/oapv_metadata.c):

• Check md->mdp_num < OAPV_MAX_NUM_META_PAYLOADS and return OAPV_ERR_REACHED_MAX before allocating and appending a new metadata payload entry.

Testing

• Verified all 24 ctest unit/conformance tests pass with AddressSanitizer and UndefinedBehaviorSanitizer.

[kpchoi]

OAPV_MAX_NUM_META_PAYLOADS is defined as the maximum number of metadata payloads per access unit, not per metadata group. oapvm_get_all() also checks it against the total over all groups. With a per-group check, up to 16 × 128 payloads can still be accepted by oapvm_set(), and the error only shows up later in oapvm_get_all().

It is suggested that the check count the payloads of all groups instead. Since oapvm_get_all() already has the same loop, a small static helper can be shared by both:

static int meta_get_num_mdp(oapvm_ctx_t *ctx)
{
    int num = 0;
    for(int i = 0; i < ctx->num; i++) {
        num += ctx->md_arr[i].mdp_num;
    }
    return num;
}

and in oapvm_set():

oapv_assert_gv(meta_get_num_mdp(ctx) < OAPV_MAX_NUM_META_PAYLOADS, ret, OAPV_ERR_REACHED_MAX, ERR);

[fkyslov]

Updated per review feedback: added meta_get_num_mdp(ctx) to count total metadata payloads across all groups in the access unit, enforced meta_get_num_mdp(ctx) < OAPV_MAX_NUM_META_PAYLOADS in oapvm_set(), and reused meta_get_num_mdp(ctx) in oapvm_get_all().

[kpchoi]

LGTM