[PATCH v2 03/14] refs: fully reset `struct ref_iterator::ref` on iteration
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Oct 8, 2025, 15:50 UTC
- Message-ID
- <20251008-b4-pks-ref-filter-skip-parsing-objects-v2-3-76e30d5c9542@pks.im>
- In-Reply-To
- <20251008-b4-pks-ref-filter-skip-parsing-objects-v2-0-76e30d5c9542@pks.im>
With the introduction of the `struct ref_iterator::ref` field it now is a whole lot easier to introduce new fields that become accessible to the caller without having to adapt every single callsite. But there's a downside: when a new field is introduced we always have to adapt all backends to set that field.
This isn't something we can avoid in the general case: when the new field is expected to be populated by all backends we of course cannot avoid doing so. But new fields may be entirely optional, in which case we'd still have such churn. And furthermore, it is very easy right now to leak state from a previous iteration into the next iteration.
Address this issue by ensuring that the reference backends all fully reset the field on every single iteration. This ensures that no state from previous iterations can leak into the next one. And it ensures that any newly introduced fields will be zeroed out by default.
Note that we don't have to explicitly adapt the "files" backend, as it uses the `cache_ref_iterator` internally. Furthermore, other "wrapping" iterators like for example the `prefix_ref_iterator` copy around the whole reference, so these don't need to be adapted either.
Signed-off-by: Patrick Steinhardt <ps@pks.im> --- refs/packed-backend.c | 3 ++- refs/ref-cache.c | 1 + refs/reftable-backend.c | 1 + 3 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 7987acdc96..711e07f832 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -882,6 +882,7 @@ static int next_record(struct packed_ref_iterator *iter) { const char *p, *eol; + memset(&iter->base.ref, 0, sizeof(iter->base.ref)); strbuf_reset(&iter->refname_buf); /* @@ -916,6 +917,7 @@ static int next_record(struct packed_ref_iterator *iter) !isspace(*p++)) die_invalid_line(iter->snapshot->refs->path, iter->pos, iter->eof - iter->pos); + iter->base.ref.oid = &iter->oid; eol = memchr(p, '\n', iter->eof - p); if (!eol) @@ -1194,7 +1196,6 @@ static struct ref_iterator *packed_ref_iterator_begin( iter->snapshot = snapshot; acquire_snapshot(snapshot); strbuf_init(&iter->refname_buf, 0); - iter->base.ref.oid = &iter->oid; iter->repo = ref_store->repo; iter->flags = flags; diff --git a/refs/ref-cache.c b/refs/ref-cache.c index 97555fa118..4726de430d 100644 --- a/refs/ref-cache.c +++ b/refs/ref-cache.c @@ -425,6 +425,7 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator) level->prefix_state = entry_prefix_state; level->index = -1; } else { + memset(&iter->base.ref, 0, sizeof(iter->base.ref)); iter->base.ref.name = entry->name; iter->base.ref.target = entry->u.value.referent; iter->base.ref.oid = &entry->u.value.oid; diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c index 7fbc77492e..1e047fddae 100644 --- a/refs/reftable-backend.c +++ b/refs/reftable-backend.c @@ -703,6 +703,7 @@ static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator) &iter->oid, flags)) continue; + memset(&iter->base.ref, 0, sizeof(iter->base.ref)); iter->base.ref.name = iter->ref.refname; iter->base.ref.target = referent; iter->base.ref.oid = &iter->oid;
-- 2.51.0.764.g787ff6f08a.dirty