reftable/iter: handle allocation failures when creating indexed table iter

Handle allocation failures in `new_indexed_table_ref_iter()`. While at
it, rename the function to match our coding style.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

reftable/iter.c

@@ -181,14 +181,20 @@ static int indexed_table_ref_iter_next(void *p, struct reftable_record *rec)
 	}
 }
 
-int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
+int indexed_table_ref_iter_new(struct indexed_table_ref_iter **dest,
 			       struct reftable_reader *r, uint8_t *oid,
 			       int oid_len, uint64_t *offsets, int offset_len)
 {
 	struct indexed_table_ref_iter empty = INDEXED_TABLE_REF_ITER_INIT;
-	struct indexed_table_ref_iter *itr = reftable_calloc(1, sizeof(*itr));
+	struct indexed_table_ref_iter *itr;
 	int err = 0;
 
+	itr = reftable_calloc(1, sizeof(*itr));
+	if (!itr) {
+		err = REFTABLE_OUT_OF_MEMORY_ERROR;
+		goto out;
+	}
+
 	*itr = empty;
 	itr->r = r;
 	strbuf_add(&itr->oid, oid, oid_len);
@@ -197,10 +203,16 @@ int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
 	itr->offset_len = offset_len;
 
 	err = indexed_table_ref_iter_next_block(itr);
+	if (err < 0)
+		goto out;
+
+	*dest = itr;
+	err = 0;
+
+out:
 	if (err < 0) {
+		*dest = NULL;
 		reftable_free(itr);
-	} else {
-		*dest = itr;
 	}
 	return err;
 }

reftable/iter.h

@@ -82,7 +82,7 @@ void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
 					  struct indexed_table_ref_iter *itr);
 
 /* Takes ownership of `offsets` */
-int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest,
+int indexed_table_ref_iter_new(struct indexed_table_ref_iter **dest,
 			       struct reftable_reader *r, uint8_t *oid,
 			       int oid_len, uint64_t *offsets, int offset_len);
 

reftable/reader.c

@@ -715,7 +715,7 @@ static int reftable_reader_refs_for_indexed(struct reftable_reader *r,
 		goto done;
 	}
 
-	err = new_indexed_table_ref_iter(&itr, r, oid, hash_size(r->hash_id),
+	err = indexed_table_ref_iter_new(&itr, r, oid, hash_size(r->hash_id),
 					 got.u.obj.offsets,
 					 got.u.obj.offset_len);
 	if (err < 0)
@@ -740,6 +740,11 @@ static int reftable_reader_refs_for_unindexed(struct reftable_reader *r,
 	int err;
 
 	REFTABLE_ALLOC_ARRAY(ti, 1);
+	if (!ti) {
+		err = REFTABLE_OUT_OF_MEMORY_ERROR;
+		goto out;
+	}
+
 	table_iter_init(ti, r);
 	err = table_iter_seek_start(ti, BLOCK_TYPE_REF, 0);
 	if (err < 0)