[PATCH 05/19] reftable/record: stop using `BUG()` in `reftable_record_init()`

[Patrick Steinhardt <ps@xxxxxx>]

We're aborting the program via `BUG()` in case `reftable_record_init()`
was invoked with an unknown record type. This is bad because we may now
die in library code, and because it makes us depend on the Git codebase.

Refactor the code such that `reftable_record_init()` can return an error
code to the caller. Adapt any callers accordingly.

Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
 reftable/block.c                 | 4 +++-
 reftable/merged.c                | 5 ++++-
 reftable/reader.c                | 5 ++++-
 reftable/record.c                | 8 ++++----
 reftable/record.h                | 4 ++--
 t/unit-tests/t-reftable-pq.c     | 6 +++---
 t/unit-tests/t-reftable-record.c | 2 +-
 7 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/reftable/block.c b/reftable/block.c
index 8ac865ce78..255d566854 100644
--- a/reftable/block.c
+++ b/reftable/block.c
@@ -509,7 +509,9 @@ int block_iter_seek_key(struct block_iter *it, const struct block_reader *br,
 	it->block_len = br->block_len;
 	it->hash_size = br->hash_size;
 
-	reftable_record_init(&rec, block_reader_type(br));
+	err = reftable_record_init(&rec, block_reader_type(br));
+	if (err < 0)
+		goto done;
 
 	/*
 	 * We're looking for the last entry less than the wanted key so that
diff --git a/reftable/merged.c b/reftable/merged.c
index e72b39e178..4156eec07f 100644
--- a/reftable/merged.c
+++ b/reftable/merged.c
@@ -253,7 +253,10 @@ int merged_table_init_iter(struct reftable_merged_table *mt,
 	}
 
 	for (size_t i = 0; i < mt->readers_len; i++) {
-		reftable_record_init(&subiters[i].rec, typ);
+		ret = reftable_record_init(&subiters[i].rec, typ);
+		if (ret < 0)
+			goto out;
+
 		ret = reader_init_iter(mt->readers[i], &subiters[i].iter, typ);
 		if (ret < 0)
 			goto out;
diff --git a/reftable/reader.c b/reftable/reader.c
index 3f2e4b2800..de6e6dd932 100644
--- a/reftable/reader.c
+++ b/reftable/reader.c
@@ -360,7 +360,10 @@ static int table_iter_seek_linear(struct table_iter *ti,
 	struct reftable_record rec;
 	int err;
 
-	reftable_record_init(&rec, reftable_record_type(want));
+	err = reftable_record_init(&rec, reftable_record_type(want));
+	if (err < 0)
+		goto done;
+
 	err = reftable_record_key(want, &want_key);
 	if (err < 0)
 		goto done;
diff --git a/reftable/record.c b/reftable/record.c
index d1664c47ca..31985bb977 100644
--- a/reftable/record.c
+++ b/reftable/record.c
@@ -1301,7 +1301,7 @@ reftable_record_vtable(struct reftable_record *rec)
 	abort();
 }
 
-void reftable_record_init(struct reftable_record *rec, uint8_t typ)
+int reftable_record_init(struct reftable_record *rec, uint8_t typ)
 {
 	memset(rec, 0, sizeof(*rec));
 	rec->type = typ;
@@ -1310,11 +1310,11 @@ void reftable_record_init(struct reftable_record *rec, uint8_t typ)
 	case BLOCK_TYPE_REF:
 	case BLOCK_TYPE_LOG:
 	case BLOCK_TYPE_OBJ:
-		return;
+		return 0;
 	case BLOCK_TYPE_INDEX:
 		reftable_buf_init(&rec->u.idx.last_key);
-		return;
+		return 0;
 	default:
-		BUG("unhandled record type");
+		return REFTABLE_API_ERROR;
 	}
 }
diff --git a/reftable/record.h b/reftable/record.h
index c7755a4d75..e1846c294b 100644
--- a/reftable/record.h
+++ b/reftable/record.h
@@ -130,8 +130,8 @@ struct reftable_record {
 	} u;
 };
 
-/* Initialize the reftable record for the given type */
-void reftable_record_init(struct reftable_record *rec, uint8_t typ);
+/* Initialize the reftable record for the given type. */
+int reftable_record_init(struct reftable_record *rec, uint8_t typ);
 
 /* see struct record_vtable */
 int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b);
diff --git a/t/unit-tests/t-reftable-pq.c b/t/unit-tests/t-reftable-pq.c
index f3f8a0cdf3..d8a4c283a1 100644
--- a/t/unit-tests/t-reftable-pq.c
+++ b/t/unit-tests/t-reftable-pq.c
@@ -32,7 +32,7 @@ static void t_pq_record(void)
 	char *last = NULL;
 
 	for (i = 0; i < N; i++) {
-		reftable_record_init(&recs[i], BLOCK_TYPE_REF);
+		check(!reftable_record_init(&recs[i], BLOCK_TYPE_REF));
 		recs[i].u.ref.refname = xstrfmt("%02"PRIuMAX, (uintmax_t)i);
 	}
 
@@ -72,7 +72,7 @@ static void t_pq_index(void)
 	size_t N = ARRAY_SIZE(recs), i;
 
 	for (i = 0; i < N; i++) {
-		reftable_record_init(&recs[i], BLOCK_TYPE_REF);
+		check(!reftable_record_init(&recs[i], BLOCK_TYPE_REF));
 		recs[i].u.ref.refname = (char *) "refs/heads/master";
 	}
 
@@ -111,7 +111,7 @@ static void t_merged_iter_pqueue_top(void)
 	size_t N = ARRAY_SIZE(recs), i;
 
 	for (i = 0; i < N; i++) {
-		reftable_record_init(&recs[i], BLOCK_TYPE_REF);
+		check(!reftable_record_init(&recs[i], BLOCK_TYPE_REF));
 		recs[i].u.ref.refname = (char *) "refs/heads/master";
 	}
 
diff --git a/t/unit-tests/t-reftable-record.c b/t/unit-tests/t-reftable-record.c
index d49d2a2729..6540bd20e3 100644
--- a/t/unit-tests/t-reftable-record.c
+++ b/t/unit-tests/t-reftable-record.c
@@ -17,7 +17,7 @@ static void t_copy(struct reftable_record *rec)
 	uint8_t typ;
 
 	typ = reftable_record_type(rec);
-	reftable_record_init(&copy, typ);
+	check(!reftable_record_init(&copy, typ));
 	reftable_record_copy_from(&copy, rec, REFTABLE_HASH_SIZE_SHA1);
 	/* do it twice to catch memory leaks */
 	reftable_record_copy_from(&copy, rec, REFTABLE_HASH_SIZE_SHA1);

-- 
2.48.1.362.g079036d154.dirty