db: Implement skaffolding for the dispatch of DB-specific functions

These functions implement the lookup of the query, and the dispatch to the
DB-specific functions that do the actual heavy lifting.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

wallet/db.c

@@ -554,6 +554,50 @@ sqlite3_stmt *db_select_prepare_(const char *location, struct db *db, const char
 	return stmt;
 }
 
+struct db_stmt *db_prepare_v2_(const char *location, struct db *db,
+			       const char *query_id)
+{
+	struct db_stmt *stmt = tal(db, struct db_stmt);
+	size_t num_slots;
+	stmt->query = NULL;
+
+	/* Normalize query_id paths, because unit tests are compiled with this
+	 * prefix. */
+	if (strncmp(query_id, "./", 2) == 0)
+		query_id += 2;
+
+	/* Look up the query by its ID */
+	for (size_t i = 0; i < db->config->num_queries; i++) {
+		if (streq(query_id, db->config->queries[i].query)) {
+			stmt->query = &db->config->queries[i];
+			break;
+		}
+	}
+	if (stmt->query == NULL)
+		fatal("Could not resolve query %s", query_id);
+
+	num_slots = stmt->query->placeholders;
+	/* Allocate the slots for placeholders/bindings, zeroed next since
+	 * that sets the type to DB_BINDING_UNINITIALIZED for later checks. */
+	stmt->bindings = tal_arr(stmt, struct db_binding, num_slots);
+	for (size_t i=0; i<num_slots; i++)
+		stmt->bindings[i].type = DB_BINDING_UNINITIALIZED;
+
+	stmt->location = location;
+	stmt->error = NULL;
+	stmt->db = db;
+	return stmt;
+}
+
+void db_stmt_free(struct db_stmt *stmt)
+{
+	stmt->db->config->stmt_free_fn(stmt);
+}
+
+#define db_prepare_v2(db,query) \
+	db_prepare_v2_(__FILE__ ":" stringify(__LINE__), db, query)
+
+
 bool db_select_step_(const char *location, struct db *db, struct sqlite3_stmt *stmt)
 {
 	int ret;
@@ -1247,3 +1291,64 @@ struct timeabs sqlite3_column_timeabs(sqlite3_stmt *stmt, int col)
 	return t;
 
 }
+
+void db_bind_null(struct db_stmt *stmt, int pos)
+{
+	assert(pos < tal_count(stmt->bindings));
+	stmt->bindings[pos].type = DB_BINDING_NULL;
+}
+
+void db_bind_int(struct db_stmt *stmt, int pos, int val)
+{
+	assert(pos < tal_count(stmt->bindings));
+	stmt->bindings[pos].type = DB_BINDING_INT;
+	stmt->bindings[pos].v.i = val;
+}
+
+void db_bind_u64(struct db_stmt *stmt, int pos, u64 val)
+{
+	assert(pos < tal_count(stmt->bindings));
+	stmt->bindings[pos].type = DB_BINDING_UINT64;
+	stmt->bindings[pos].v.u64 = val;
+}
+
+void db_bind_blob(struct db_stmt *stmt, int pos, u8 *val, size_t len)
+{
+	assert(pos < tal_count(stmt->bindings));
+	stmt->bindings[pos].type = DB_BINDING_BLOB;
+	stmt->bindings[pos].v.blob = val;
+	stmt->bindings[pos].len = len;
+}
+
+void db_bind_text(struct db_stmt *stmt, int pos, const char *val)
+{
+	assert(pos < tal_count(stmt->bindings));
+	stmt->bindings[pos].type = DB_BINDING_TEXT;
+	stmt->bindings[pos].v.text = val;
+	stmt->bindings[pos].len = strlen(val);
+}
+
+bool db_exec_prepared_v2(struct db_stmt *stmt TAKES)
+{
+	const char *expanded_sql;
+	bool ret = stmt->db->config->exec_fn(stmt);
+	if (stmt->db->config->expand_fn != NULL && ret &&
+	    !stmt->query->readonly) {
+		expanded_sql = stmt->db->config->expand_fn(stmt);
+		tal_arr_expand(&stmt->db->changes,
+			       tal_strdup(stmt->db->changes, expanded_sql));
+	}
+
+	/* The driver itself doesn't call `fatal` since we want to override it
+	 * for testing. Instead we check here that the error message is set if
+	 * we report an error. */
+	if (!ret) {
+		assert(stmt->error);
+		db_fatal("Error executing statement: %s", stmt->error);
+	}
+
+	if (taken(stmt))
+	    tal_free(stmt);
+
+	return ret;
+}

wallet/db.h

@@ -18,7 +18,7 @@
 struct lightningd;
 struct log;
 struct node_id;
-
+struct db_stmt;
 struct db;
 
 /**
@@ -241,4 +241,19 @@ void sqlite3_bind_amount_sat(sqlite3_stmt *stmt, int col,
 void sqlite3_bind_timeabs(sqlite3_stmt *stmt, int col, struct timeabs t);
 struct timeabs sqlite3_column_timeabs(sqlite3_stmt *stmt, int col);
 
+
+void db_bind_null(struct db_stmt *stmt, int pos);
+void db_bind_int(struct db_stmt *stmt, int pos, int val);
+void db_bind_u64(struct db_stmt *stmt, int pos, u64 val);
+void db_bind_blob(struct db_stmt *stmt, int pos, u8 *val, size_t len);
+void db_bind_text(struct db_stmt *stmt, int pos, const char *val);
+bool db_exec_prepared_v2(struct db_stmt *stmt TAKES);
+
+void db_stmt_free(struct db_stmt *stmt);
+
+struct db_stmt *db_prepare_v2_(const char *location, struct db *db,
+			       const char *query_id);
+#define db_prepare_v2(db,query) \
+	db_prepare_v2_(__FILE__ ":" stringify(__LINE__), db, query)
+
 #endif /* LIGHTNING_WALLET_DB_H */

wallet/test/run-db.c

@@ -24,6 +24,9 @@ size_t bigsize_get(const u8 *p UNNEEDED, size_t max UNNEEDED, bigsize_t *val UNN
 /* Generated stub for bigsize_put */
 size_t bigsize_put(u8 buf[BIGSIZE_MAX_LEN] UNNEEDED, bigsize_t v UNNEEDED)
 { fprintf(stderr, "bigsize_put called!\n"); abort(); }
+/* Generated stub for fatal */
+void   fatal(const char *fmt UNNEEDED, ...)
+{ fprintf(stderr, "fatal called!\n"); abort(); }
 /* AUTOGENERATED MOCKS END */
 
 static char *db_err;