Fix return type of compressed_data_info

The function `compressed_data_info` returns a record containing `name`
but copies the data from `cstring`. Since `heap_form_tuple` expects a
`name` value as source as well, it will copy too much data from the
source, leading to ASAN complaining about copying outside the allocated
range of data.

.unreleased/pr_7187

@@ -0,0 +1 @@
+Fixes: #7187 Fix return type of compressed_data_info

sql/pre_install/types.functions.sql

@@ -35,7 +35,7 @@ CREATE OR REPLACE FUNCTION _timescaledb_functions.compressed_data_recv(internal)
    LANGUAGE C IMMUTABLE STRICT;
 
 CREATE OR REPLACE FUNCTION _timescaledb_functions.compressed_data_info(_timescaledb_internal.compressed_data)
-    RETURNS TABLE (algorithm name, has_nulls bool)
+    RETURNS TABLE (algorithm cstring, has_nulls bool)
     LANGUAGE C STRICT IMMUTABLE
     AS '@MODULE_PATHNAME@', 'ts_compressed_data_info';
 

sql/updates/latest-dev.sql

@@ -1,3 +1,5 @@
 CREATE FUNCTION _timescaledb_functions.compressed_data_info(_timescaledb_internal.compressed_data)
-    RETURNS TABLE (algorithm name, has_nulls bool)
-    AS 'SELECT NULL,FALSE' LANGUAGE SQL STRICT IMMUTABLE SET search_path = pg_catalog, pg_temp;
+    RETURNS TABLE (algorithm cstring, has_nulls bool)
+    AS $$ SELECT ''::cstring,FALSE $$
+    LANGUAGE SQL STRICT IMMUTABLE
+    SET search_path = pg_catalog, pg_temp;