Refactor all the 'H5VL_*_optional' callbacks to move the type of operation out

of the va_list, so it's at least possible for another connector to know what
the operation is and decide whether to implement it or not.

Added a new VOL sub-class called "introspect" where callbacks that report
information about the connector or container can be placed.  Added an
'opt_query' callback to this sub-class, for a connector to report back
to the library whether a particular optional callback operation is supported.
Also added a 'get_conn_cls' introspection callback, to retrieve the H5VL_class_t
of a connector (either the "current" connector, H5VL_GET_CONN_LVL_CURR, or
the terminal connector, H5VL_GET_CONN_LVL_TERM).

Moved the "post open" operation from a file 'specific' operation to a file
'optional' operation, now that it's possible to detect (with the 'opt_query'
introspection callback) whether a VOL connector implements an optional
operation, without just returning an error.

Added new internal VOL helper routines: H5VL_object_is_native, to determine
if an object is in (or is a) native file, and H5VL_file_is_same, to determine
if two objects are in (or are) the same terminal VOL connector's container.
(And moved the special handling for FILE_IS_EQUAL operation out of internal VOL
callback routine into H5VL_file_is_same)

Made new dataset 'get' operation for H5Dvlen_get_buf_size, aligning it better
with other 'get' operations in API.

Fixed several issues with pass-through connectors, which are now passing the
'make check-passthrough-vol' tests again.

A bunch of warning and style cleanups as well.

1 files changed, 52 insertions, 0 deletions

diff --git a/src/H5VLnative_introspect.c b/src/H5VLnative_introspect.c
new file mode 100644
index 0000000..45b8d8c
--- /dev/null
+++ b/src/H5VLnative_introspect.c
@@ -0,0 +1,52 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Purpose:     Connector/container introspection callbacks for the native VOL connector
+ *
+ */
+
+#include "H5private.h"          /* Generic Functions                        */
+#include "H5Eprivate.h"         /* Error handling                           */
+#include "H5VLprivate.h"        /* Virtual Object Layer                     */
+
+#include "H5VLnative_private.h" /* Native VOL connector                     */
+
+/* Note: H5VL__native_introspect_get_conn_cls is in src/H5VLnative.c so that
+ *      it can return the address of the staticly declared class struct.
+ */
+
+
+/*---------------------------------------------------------------------------
+ * Function:    H5VL__native_introspect_opt_query
+ *
+ * Purpose:     Query if an optional operation is supported by this connector
+ *
+ * Returns:     SUCCEED (Can't fail)
+ *
+ *---------------------------------------------------------------------------
+ */
+herr_t
+H5VL__native_introspect_opt_query(void H5_ATTR_UNUSED *obj, H5VL_subclass_t H5_ATTR_UNUSED cls,
+    int H5_ATTR_UNUSED opt_type, hbool_t *supported)
+{
+    FUNC_ENTER_PACKAGE_NOERR
+
+    /* Sanity check */
+    HDassert(supported);
+
+    /* The native VOL connector supports all optional operations */
+    *supported = TRUE;
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5VL__native_introspect_opt_query() */
+