tdb: use TDB_RECOVERY_INVALID_MAGIC rather than 0

ccan/tdb/check.c

@@ -370,7 +370,7 @@ int tdb_check(struct tdb_context *tdb,
 				goto free;
 			break;
 		case TDB_RECOVERY_MAGIC:
-		case 0: /* Used for invalid (or in-progress) recovery area. */ 
+		case TDB_RECOVERY_INVALID_MAGIC:
 			if (recovery_start != off) {
 				TDB_LOG((tdb, TDB_DEBUG_ERROR,
 					 "Unexpected recovery record at offset %d\n",

ccan/tdb/tdb_private.h

@@ -69,6 +69,7 @@ typedef uint32_t tdb_off_t;
 #define TDB_FREE_MAGIC (~TDB_MAGIC)
 #define TDB_DEAD_MAGIC (0xFEE1DEAD)
 #define TDB_RECOVERY_MAGIC (0xf53bc0e7U)
+#define TDB_RECOVERY_INVALID_MAGIC (0x0)
 #define TDB_ALIGNMENT 4
 #define DEFAULT_HASH_SIZE 131
 #define FREELIST_TOP (sizeof(struct tdb_header))

ccan/tdb/transaction.c

@@ -494,10 +494,10 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
 
 	if (tdb->transaction->magic_offset) {
 		const struct tdb_methods *methods = tdb->transaction->io_methods;
-		uint32_t zero = 0;
+		uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
 
 		/* remove the recovery marker */
-		if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
+		if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
 		transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
 			ret = -1;
@@ -805,7 +805,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	rec = (struct tdb_record *)data;
 	memset(rec, 0, sizeof(*rec));
 
-	rec->magic    = 0;
+	rec->magic    = TDB_RECOVERY_INVALID_MAGIC;
 	rec->data_len = recovery_size;
 	rec->rec_len  = recovery_max_size;
 	rec->key_len  = old_map_size;