Expand 'opt_query' VOL callback to return a bitfield instead of a flag (#136)

* Expand 'opt_query' VOL callback to return a bitfield instead of a flag

* Correct pastos

13 files changed, 258 insertions, 47 deletions

diff --git a/src/H5D.c b/src/H5D.c
index bd2fa47..3a4d463 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -1187,7 +1187,7 @@ herr_t
 H5Dvlen_get_buf_size(hid_t dataset_id, hid_t type_id, hid_t space_id, hsize_t *size /*out*/)
 {
     H5VL_object_t *vol_obj;   /* Dataset for this operation */
-    hbool_t        supported; /* Whether 'get vlen buf size' operation is supported by VOL connector */
+    uint64_t       supported; /* Whether 'get vlen buf size' operation is supported by VOL connector */
     herr_t         ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API(FAIL)
@@ -1204,11 +1204,12 @@ H5Dvlen_get_buf_size(hid_t dataset_id, hid_t type_id, hid_t space_id, hsize_t *s
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid 'size' pointer")
 
     /* Check if the 'get_vlen_buf_size' callback is supported */
-    supported = FALSE;
+    supported = 0;
     if (H5VL_introspect_opt_query(vol_obj, H5VL_SUBCLS_DATASET, H5VL_NATIVE_DATASET_GET_VLEN_BUF_SIZE,
                                   &supported) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't check for 'get vlen buf size' operation")
-    if (supported) {
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, H5I_INVALID_HID,
+                    "can't check for 'get vlen buf size' operation")
+    if (supported & H5VL_OPT_QUERY_SUPPORTED) {
         /* Make the 'get_vlen_buf_size' callback */
         if (H5VL_dataset_optional(vol_obj, H5VL_NATIVE_DATASET_GET_VLEN_BUF_SIZE, H5P_DATASET_XFER_DEFAULT,
                                   H5_REQUEST_NULL, type_id, space_id, size) < 0)
diff --git a/src/H5F.c b/src/H5F.c
index de10aed..26c8ecb 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -476,7 +476,7 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
     H5P_genplist_t *      plist;           /* Property list pointer                    */
     H5VL_connector_prop_t connector_prop;  /* Property for VOL connector ID & info     */
     H5VL_object_t *       vol_obj = NULL;  /* VOL object for file                      */
-    hbool_t               supported;       /* Whether 'post open' operation is supported by VOL connector */
+    uint64_t              supported;       /* Whether 'post open' operation is supported by VOL connector */
     hid_t                 ret_value;       /* return value                             */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
@@ -540,10 +540,10 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid object identifier")
 
     /* Make the 'post open' callback */
-    supported = FALSE;
+    supported = 0;
     if (H5VL_introspect_opt_query(vol_obj, H5VL_SUBCLS_FILE, H5VL_NATIVE_FILE_POST_OPEN, &supported) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't check for 'post open' operation")
-    if (supported)
+    if (supported & H5VL_OPT_QUERY_SUPPORTED)
         if (H5VL_file_optional(vol_obj, H5VL_NATIVE_FILE_POST_OPEN, H5P_DATASET_XFER_DEFAULT,
                                H5_REQUEST_NULL) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to make file 'post open' callback")
@@ -576,7 +576,7 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
     H5P_genplist_t *      plist;           /* Property list pointer                    */
     H5VL_connector_prop_t connector_prop;  /* Property for VOL connector ID & info     */
     H5VL_object_t *       vol_obj = NULL;  /* VOL object for file                      */
-    hbool_t               supported;       /* Whether 'post open' operation is supported by VOL connector */
+    uint64_t              supported;       /* Whether 'post open' operation is supported by VOL connector */
     hid_t                 ret_value;       /* Return value                             */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
@@ -628,10 +628,10 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "invalid object identifier")
 
     /* Make the 'post open' callback */
-    supported = FALSE;
+    supported = 0;
     if (H5VL_introspect_opt_query(vol_obj, H5VL_SUBCLS_FILE, H5VL_NATIVE_FILE_POST_OPEN, &supported) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't check for 'post open' operation")
-    if (supported)
+    if (supported & H5VL_OPT_QUERY_SUPPORTED)
         if (H5VL_file_optional(vol_obj, H5VL_NATIVE_FILE_POST_OPEN, H5P_DATASET_XFER_DEFAULT,
                                H5_REQUEST_NULL) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to make file 'post open' callback")
@@ -905,7 +905,7 @@ H5Freopen(hid_t file_id)
 {
     void *         file    = NULL; /* File struct for new file */
     H5VL_object_t *vol_obj = NULL; /* VOL object for file                      */
-    hbool_t        supported;      /* Whether 'post open' operation is supported by VOL connector */
+    uint64_t       supported;      /* Whether 'post open' operation is supported by VOL connector */
     hid_t          ret_value = H5I_INVALID_HID; /* Return value */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
@@ -932,10 +932,10 @@ H5Freopen(hid_t file_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid object identifier")
 
     /* Make the 'post open' callback */
-    supported = FALSE;
+    supported = 0;
     if (H5VL_introspect_opt_query(vol_obj, H5VL_SUBCLS_FILE, H5VL_NATIVE_FILE_POST_OPEN, &supported) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't check for 'post open' operation")
-    if (supported)
+    if (supported & H5VL_OPT_QUERY_SUPPORTED)
         if (H5VL_file_optional(vol_obj, H5VL_NATIVE_FILE_POST_OPEN, H5P_DATASET_XFER_DEFAULT,
                                H5_REQUEST_NULL) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to make file 'post open' callback")
diff --git a/src/H5Rint.c b/src/H5Rint.c
index e0d9ffc..40f48a1 100644
--- a/src/H5Rint.c
+++ b/src/H5Rint.c
@@ -546,7 +546,7 @@ H5R__reopen_file(H5R_ref_priv_t *ref, hid_t fapl_id)
     void *                new_file = NULL; /* File object opened */
     H5VL_connector_prop_t connector_prop;  /* Property for VOL connector ID & info     */
     H5VL_object_t *       vol_obj = NULL;  /* VOL object for file */
-    hbool_t               supported;       /* Whether 'post open' operation is supported by VOL connector */
+    uint64_t              supported;       /* Whether 'post open' operation is supported by VOL connector */
     hid_t                 ret_value = H5I_INVALID_HID;
 
     FUNC_ENTER_PACKAGE
@@ -585,10 +585,10 @@ H5R__reopen_file(H5R_ref_priv_t *ref, hid_t fapl_id)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, H5I_INVALID_HID, "invalid object identifier")
 
     /* Make the 'post open' callback */
-    supported = FALSE;
+    supported = 0;
     if (H5VL_introspect_opt_query(vol_obj, H5VL_SUBCLS_FILE, H5VL_NATIVE_FILE_POST_OPEN, &supported) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, H5I_INVALID_HID, "can't check for 'post open' operation")
-    if (supported)
+    if (supported & H5VL_OPT_QUERY_SUPPORTED)
         if (H5VL_file_optional(vol_obj, H5VL_NATIVE_FILE_POST_OPEN, H5P_DATASET_XFER_DEFAULT,
                                H5_REQUEST_NULL) < 0)
             HGOTO_ERROR(H5E_REFERENCE, H5E_CANTINIT, H5I_INVALID_HID,
diff --git a/src/H5VL.c b/src/H5VL.c
index 272111c..a06120c 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -895,7 +895,8 @@ done:
  * Function:    H5VLquery_optional
  *
  * Purpose:     Determine if a VOL connector supports a particular optional
- *              callback operation.
+ *              callback operation, and a general sense of the operation's
+ *              behavior.
  *
  * Return:      Success:    Non-negative
  *              Failure:    Negative
@@ -903,23 +904,23 @@ done:
  *---------------------------------------------------------------------------
  */
 herr_t
-H5VLquery_optional(hid_t obj_id, H5VL_subclass_t subcls, int opt_type, hbool_t *supported)
+H5VLquery_optional(hid_t obj_id, H5VL_subclass_t subcls, int opt_type, uint64_t *flags /*out*/)
 {
     H5VL_object_t *vol_obj   = NULL;
     herr_t         ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "iVSIs*b", obj_id, subcls, opt_type, supported);
+    H5TRACE4("e", "iVSIsx", obj_id, subcls, opt_type, flags);
 
     /* Check args */
-    if (NULL == supported)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid supported pointer")
+    if (NULL == flags)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid 'flags' pointer")
     if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Query the connector */
-    if (H5VL_introspect_opt_query(vol_obj, subcls, opt_type, supported) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "unable to query VOL connector support")
+    if (H5VL_introspect_opt_query(vol_obj, subcls, opt_type, flags) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "unable to query VOL connector operation")
 
 done:
     FUNC_LEAVE_API(ret_value)
diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index 460a170..427e447 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -152,7 +152,7 @@ static herr_t H5VL__object_optional(void *obj, const H5VL_class_t *cls, H5VL_obj
 static herr_t H5VL__introspect_get_conn_cls(void *obj, const H5VL_class_t *cls, H5VL_get_conn_lvl_t lvl,
                                             const H5VL_class_t **conn_cls);
 static herr_t H5VL__introspect_opt_query(void *obj, const H5VL_class_t *cls, H5VL_subclass_t subcls,
-                                         int opt_type, hbool_t *supported);
+                                         int opt_type, uint64_t *flags);
 static herr_t H5VL__request_wait(void *req, const H5VL_class_t *cls, uint64_t timeout, H5ES_status_t *status);
 static herr_t H5VL__request_notify(void *req, const H5VL_class_t *cls, H5VL_request_notify_t cb, void *ctx);
 static herr_t H5VL__request_cancel(void *req, const H5VL_class_t *cls);
@@ -5849,7 +5849,7 @@ done:
  */
 static herr_t
 H5VL__introspect_opt_query(void *obj, const H5VL_class_t *cls, H5VL_subclass_t subcls, int opt_type,
-                           hbool_t *supported)
+                           uint64_t *flags)
 {
     herr_t ret_value = SUCCEED; /* Return value */
 
@@ -5860,7 +5860,7 @@ H5VL__introspect_opt_query(void *obj, const H5VL_class_t *cls, H5VL_subclass_t s
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "VOL connector has no 'opt_query' method")
 
     /* Call the corresponding VOL callback */
-    if ((cls->introspect_cls.opt_query)(obj, subcls, opt_type, supported) < 0)
+    if ((cls->introspect_cls.opt_query)(obj, subcls, opt_type, flags) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't query optional operation support")
 
 done:
@@ -5879,8 +5879,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_introspect_opt_query(const H5VL_object_t *vol_obj, H5VL_subclass_t subcls, int opt_type,
-                          hbool_t *supported)
+H5VL_introspect_opt_query(const H5VL_object_t *vol_obj, H5VL_subclass_t subcls, int opt_type, uint64_t *flags)
 {
     hbool_t vol_wrapper_set = FALSE;   /* Whether the VOL object wrapping context was set up */
     herr_t  ret_value       = SUCCEED; /* Return value */
@@ -5893,7 +5892,7 @@ H5VL_introspect_opt_query(const H5VL_object_t *vol_obj, H5VL_subclass_t subcls,
     vol_wrapper_set = TRUE;
 
     /* Call the corresponding internal VOL routine */
-    if (H5VL__introspect_opt_query(vol_obj->data, vol_obj->connector->cls, subcls, opt_type, supported) < 0)
+    if (H5VL__introspect_opt_query(vol_obj->data, vol_obj->connector->cls, subcls, opt_type, flags) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't query optional operation support")
 
 done:
@@ -5917,20 +5916,20 @@ done:
  */
 herr_t
 H5VLintrospect_opt_query(void *obj, hid_t connector_id, H5VL_subclass_t subcls, int opt_type,
-                         hbool_t *supported /*out*/)
+                         uint64_t *flags /*out*/)
 {
     H5VL_class_t *cls;                 /* VOL connector's class struct */
     herr_t        ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_API_NOINIT
-    H5TRACE5("e", "*xiVSIsx", obj, connector_id, subcls, opt_type, supported);
+    H5TRACE5("e", "*xiVSIsx", obj, connector_id, subcls, opt_type, flags);
 
     /* Get class pointer */
     if (NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL connector ID")
 
     /* Call the corresponding internal VOL routine */
-    if (H5VL__introspect_opt_query(obj, cls, subcls, opt_type, supported) < 0)
+    if (H5VL__introspect_opt_query(obj, cls, subcls, opt_type, flags) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't query optional operation support")
 
 done:
diff --git a/src/H5VLconnector.h b/src/H5VLconnector.h
index 2abdca3..48f4a28 100644
--- a/src/H5VLconnector.h
+++ b/src/H5VLconnector.h
@@ -410,7 +410,7 @@ struct H5VL_class_t;
 /* Container/connector introspection routines */
 typedef struct H5VL_introspect_class_t {
     herr_t (*get_conn_cls)(void *obj, H5VL_get_conn_lvl_t lvl, const struct H5VL_class_t **conn_cls);
-    herr_t (*opt_query)(void *obj, H5VL_subclass_t cls, int opt_type, hbool_t *supported);
+    herr_t (*opt_query)(void *obj, H5VL_subclass_t cls, int opt_type, uint64_t *flags);
 } H5VL_introspect_class_t;
 
 /* Async request operation routines */
diff --git a/src/H5VLconnector_passthru.h b/src/H5VLconnector_passthru.h
index 07297e1..053d912 100644
--- a/src/H5VLconnector_passthru.h
+++ b/src/H5VLconnector_passthru.h
@@ -195,7 +195,7 @@ H5_DLL herr_t H5VLobject_optional(void *obj, hid_t connector_id, H5VL_object_opt
 H5_DLL herr_t H5VLintrospect_get_conn_cls(void *obj, hid_t connector_id, H5VL_get_conn_lvl_t lvl,
                                           const H5VL_class_t **conn_cls);
 H5_DLL herr_t H5VLintrospect_opt_query(void *obj, hid_t connector_id, H5VL_subclass_t subcls, int opt_type,
-                                       hbool_t *supported);
+                                       uint64_t *flags);
 
 /* Public wrappers for asynchronous request callbacks */
 H5_DLL herr_t H5VLrequest_wait(void *req, hid_t connector_id, uint64_t timeout, H5ES_status_t *status);
diff --git a/src/H5VLnative.h b/src/H5VLnative.h
index b81f9c1..ae52084 100644
--- a/src/H5VLnative.h
+++ b/src/H5VLnative.h
@@ -33,11 +33,17 @@
 #define H5VL_NATIVE_VERSION 0
 
 /* Values for VOL connector attribute optional VOL operations */
+/* NOTE: If new values are added here, the H5VL__native_introspect_opt_query
+ *      routine must be updated.
+ */
 #ifndef H5_NO_DEPRECATED_SYMBOLS
 #define H5VL_NATIVE_ATTR_ITERATE_OLD 0 /* H5Aiterate (deprecated routine) */
 #endif                                 /* H5_NO_DEPRECATED_SYMBOLS */
 
 /* Values for native VOL connector dataset optional VOL operations */
+/* NOTE: If new values are added here, the H5VL__native_introspect_opt_query
+ *      routine must be updated.
+ */
 #define H5VL_NATIVE_DATASET_FORMAT_CONVERT          0 /* H5Dformat_convert (internal) */
 #define H5VL_NATIVE_DATASET_GET_CHUNK_INDEX_TYPE    1 /* H5Dget_chunk_index_type      */
 #define H5VL_NATIVE_DATASET_GET_CHUNK_STORAGE_SIZE  2 /* H5Dget_chunk_storage_size    */
@@ -50,6 +56,9 @@
 #define H5VL_NATIVE_DATASET_GET_OFFSET              9 /* H5Dget_offset                */
 
 /* Values for native VOL connector file optional VOL operations */
+/* NOTE: If new values are added here, the H5VL__native_introspect_opt_query
+ *      routine must be updated.
+ */
 #define H5VL_NATIVE_FILE_CLEAR_ELINK_CACHE            0  /* H5Fclear_elink_file_cache            */
 #define H5VL_NATIVE_FILE_GET_FILE_IMAGE               1  /* H5Fget_file_image                    */
 #define H5VL_NATIVE_FILE_GET_FREE_SECTIONS            2  /* H5Fget_free_sections                 */
@@ -81,12 +90,18 @@
 #define H5VL_NATIVE_FILE_POST_OPEN                    28 /* Adjust file after open, with wrapping context */
 
 /* Values for native VOL connector group optional VOL operations */
+/* NOTE: If new values are added here, the H5VL__native_introspect_opt_query
+ *      routine must be updated.
+ */
 #ifndef H5_NO_DEPRECATED_SYMBOLS
 #define H5VL_NATIVE_GROUP_ITERATE_OLD 0 /* HG5Giterate (deprecated routine) */
 #define H5VL_NATIVE_GROUP_GET_OBJINFO 1 /* HG5Gget_objinfo (deprecated routine) */
 #endif                                  /* H5_NO_DEPRECATED_SYMBOLS */
 
 /* Values for native VOL connector object optional VOL operations */
+/* NOTE: If new values are added here, the H5VL__native_introspect_opt_query
+ *      routine must be updated.
+ */
 #define H5VL_NATIVE_OBJECT_GET_COMMENT              0 /* H5G|H5Oget_comment, H5Oget_comment_by_name   */
 #define H5VL_NATIVE_OBJECT_SET_COMMENT              1 /* H5G|H5Oset_comment, H5Oset_comment_by_name   */
 #define H5VL_NATIVE_OBJECT_DISABLE_MDC_FLUSHES      2 /* H5Odisable_mdc_flushes                       */
diff --git a/src/H5VLnative_introspect.c b/src/H5VLnative_introspect.c
index e59f7fd..68b02e6 100644
--- a/src/H5VLnative_introspect.c
+++ b/src/H5VLnative_introspect.c
@@ -35,16 +35,192 @@
  *---------------------------------------------------------------------------
  */
 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)
+H5VL__native_introspect_opt_query(void H5_ATTR_UNUSED *obj, H5VL_subclass_t subcls, int opt_type,
+                                  uint64_t *flags)
 {
-    FUNC_ENTER_PACKAGE_NOERR
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_PACKAGE
 
     /* Sanity check */
-    HDassert(supported);
+    HDassert(flags);
 
     /* The native VOL connector supports all optional operations */
-    *supported = TRUE;
+    *flags = H5VL_OPT_QUERY_SUPPORTED;
+
+    /* Set appropriate flags for each operation in each subclass */
+    switch (subcls) {
+        case H5VL_SUBCLS_NONE:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional 'none' operation")
+
+        case H5VL_SUBCLS_INFO:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional info operation")
+
+        case H5VL_SUBCLS_WRAP:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional wrapper operation")
+
+        case H5VL_SUBCLS_ATTR:
+            switch (opt_type) {
+#ifndef H5_NO_DEPRECATED_SYMBOLS
+                case H5VL_NATIVE_ATTR_ITERATE_OLD:
+                    /* Don't allow asynchronous execution, due to iterator callbacks */
+                    *flags |= H5VL_OPT_QUERY_NO_ASYNC;
+                    break;
+#endif /* H5_NO_DEPRECATED_SYMBOLS */
+
+                default:
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional attribute operation")
+                    break;
+            } /* end switch */
+            break;
+
+        case H5VL_SUBCLS_DATASET:
+            switch (opt_type) {
+                case H5VL_NATIVE_DATASET_FORMAT_CONVERT:
+                    *flags |= H5VL_OPT_QUERY_MODIFY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_DATASET_GET_CHUNK_INDEX_TYPE:
+                case H5VL_NATIVE_DATASET_GET_CHUNK_STORAGE_SIZE:
+                case H5VL_NATIVE_DATASET_GET_NUM_CHUNKS:
+                case H5VL_NATIVE_DATASET_GET_CHUNK_INFO_BY_IDX:
+                case H5VL_NATIVE_DATASET_GET_CHUNK_INFO_BY_COORD:
+                case H5VL_NATIVE_DATASET_GET_VLEN_BUF_SIZE:
+                case H5VL_NATIVE_DATASET_GET_OFFSET:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_DATASET_CHUNK_READ:
+                    *flags |= H5VL_OPT_QUERY_READ_DATA;
+                    break;
+
+                case H5VL_NATIVE_DATASET_CHUNK_WRITE:
+                    *flags |= H5VL_OPT_QUERY_WRITE_DATA;
+                    break;
+
+                default:
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional dataset operation")
+                    break;
+            } /* end switch */
+            break;
+
+        case H5VL_SUBCLS_DATATYPE:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional datatype operation")
+
+        case H5VL_SUBCLS_FILE:
+            switch (opt_type) {
+                case H5VL_NATIVE_FILE_CLEAR_ELINK_CACHE:
+                case H5VL_NATIVE_FILE_RESET_MDC_HIT_RATE:
+                case H5VL_NATIVE_FILE_SET_MDC_CONFIG:
+                    *flags |= H5VL_OPT_QUERY_MODIFY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_FILE_GET_FILE_IMAGE:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    *flags |= H5VL_OPT_QUERY_READ_DATA;
+                    break;
+
+                case H5VL_NATIVE_FILE_GET_FREE_SECTIONS:
+                case H5VL_NATIVE_FILE_GET_FREE_SPACE:
+                case H5VL_NATIVE_FILE_GET_INFO:
+                case H5VL_NATIVE_FILE_GET_MDC_CONF:
+                case H5VL_NATIVE_FILE_GET_MDC_HR:
+                case H5VL_NATIVE_FILE_GET_MDC_SIZE:
+                case H5VL_NATIVE_FILE_GET_SIZE:
+                case H5VL_NATIVE_FILE_GET_VFD_HANDLE:
+                case H5VL_NATIVE_FILE_GET_METADATA_READ_RETRY_INFO:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_FILE_START_SWMR_WRITE:
+                    *flags |= H5VL_OPT_QUERY_MODIFY_METADATA;
+                    *flags |= H5VL_OPT_QUERY_WRITE_DATA;
+                    *flags |= H5VL_OPT_QUERY_NO_ASYNC;
+                    break;
+
+                case H5VL_NATIVE_FILE_START_MDC_LOGGING:
+                case H5VL_NATIVE_FILE_STOP_MDC_LOGGING:
+                case H5VL_NATIVE_FILE_GET_MDC_LOGGING_STATUS:
+                case H5VL_NATIVE_FILE_FORMAT_CONVERT:
+                case H5VL_NATIVE_FILE_RESET_PAGE_BUFFERING_STATS:
+                case H5VL_NATIVE_FILE_GET_PAGE_BUFFERING_STATS:
+                case H5VL_NATIVE_FILE_GET_MDC_IMAGE_INFO:
+                case H5VL_NATIVE_FILE_GET_EOA:
+                case H5VL_NATIVE_FILE_INCR_FILESIZE:
+                case H5VL_NATIVE_FILE_SET_LIBVER_BOUNDS:
+                case H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG:
+                case H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG:
+                case H5VL_NATIVE_FILE_GET_MPI_ATOMICITY:
+                case H5VL_NATIVE_FILE_SET_MPI_ATOMICITY:
+                case H5VL_NATIVE_FILE_POST_OPEN:
+                    break;
+
+                default:
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional file operation")
+                    break;
+            } /* end switch */
+            break;
+
+        case H5VL_SUBCLS_GROUP:
+            switch (opt_type) {
+#ifndef H5_NO_DEPRECATED_SYMBOLS
+                case H5VL_NATIVE_GROUP_ITERATE_OLD:
+                    /* Don't allow asynchronous execution, due to iterator callbacks */
+                    *flags |= H5VL_OPT_QUERY_NO_ASYNC;
+                    break;
+
+                case H5VL_NATIVE_GROUP_GET_OBJINFO:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    break;
+#endif /* H5_NO_DEPRECATED_SYMBOLS */
+
+                default:
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional group operation")
+                    break;
+            } /* end switch */
+            break;
+
+        case H5VL_SUBCLS_LINK:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional link operation")
+
+        case H5VL_SUBCLS_OBJECT:
+            switch (opt_type) {
+                case H5VL_NATIVE_OBJECT_GET_COMMENT:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_OBJECT_SET_COMMENT:
+                    *flags |= H5VL_OPT_QUERY_MODIFY_METADATA;
+                    break;
+
+                case H5VL_NATIVE_OBJECT_DISABLE_MDC_FLUSHES:
+                case H5VL_NATIVE_OBJECT_ENABLE_MDC_FLUSHES:
+                case H5VL_NATIVE_OBJECT_ARE_MDC_FLUSHES_DISABLED:
+                    break;
+
+                case H5VL_NATIVE_OBJECT_GET_NATIVE_INFO:
+                    *flags |= H5VL_OPT_QUERY_QUERY_METADATA;
+                    break;
+
+                default:
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional object operation")
+                    break;
+            } /* end switch */
+            break;
+
+        case H5VL_SUBCLS_REQUEST:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional request operation")
+
+        case H5VL_SUBCLS_BLOB:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional blob operation")
+
+        case H5VL_SUBCLS_TOKEN:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown optional token operation")
+
+        default:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown H5VL subclass")
+    } /* end switch */
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL__native_introspect_opt_query() */
diff --git a/src/H5VLnative_private.h b/src/H5VLnative_private.h
index 0c2584c..40ab45f 100644
--- a/src/H5VLnative_private.h
+++ b/src/H5VLnative_private.h
@@ -151,7 +151,7 @@ H5_DLL herr_t H5VL__native_object_optional(void *obj, H5VL_object_optional_t opt
 H5_DLL herr_t H5VL__native_introspect_get_conn_cls(void *obj, H5VL_get_conn_lvl_t lvl,
                                                    const H5VL_class_t **conn_cls);
 H5_DLL herr_t H5VL__native_introspect_opt_query(void *obj, H5VL_subclass_t cls, int opt_type,
-                                                hbool_t *supported);
+                                                uint64_t *flags);
 
 /* Blob callbacks */
 H5_DLL herr_t H5VL__native_blob_put(void *obj, const void *buf, size_t size, void *blob_id, void *ctx);
diff --git a/src/H5VLpassthru.c b/src/H5VLpassthru.c
index 4e967d9..0725900 100644
--- a/src/H5VLpassthru.c
+++ b/src/H5VLpassthru.c
@@ -225,7 +225,7 @@ static herr_t H5VL_pass_through_object_optional(void *obj, H5VL_object_optional_
 static herr_t H5VL_pass_through_introspect_get_conn_cls(void *obj, H5VL_get_conn_lvl_t lvl,
                                                         const H5VL_class_t **conn_cls);
 static herr_t H5VL_pass_through_introspect_opt_query(void *obj, H5VL_subclass_t cls, int opt_type,
-                                                     hbool_t *supported);
+                                                     uint64_t *flags);
 
 /* Async request callbacks */
 static herr_t H5VL_pass_through_request_wait(void *req, uint64_t timeout, H5ES_status_t *status);
@@ -2635,7 +2635,7 @@ H5VL_pass_through_introspect_get_conn_cls(void *obj, H5VL_get_conn_lvl_t lvl, co
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_pass_through_introspect_opt_query(void *obj, H5VL_subclass_t cls, int opt_type, hbool_t *supported)
+H5VL_pass_through_introspect_opt_query(void *obj, H5VL_subclass_t cls, int opt_type, uint64_t *flags)
 {
     H5VL_pass_through_t *o = (H5VL_pass_through_t *)obj;
     herr_t               ret_value;
@@ -2644,7 +2644,7 @@ H5VL_pass_through_introspect_opt_query(void *obj, H5VL_subclass_t cls, int opt_t
     printf("------- PASS THROUGH VOL INTROSPECT OptQuery\n");
 #endif
 
-    ret_value = H5VLintrospect_opt_query(o->under_object, o->under_vol_id, cls, opt_type, supported);
+    ret_value = H5VLintrospect_opt_query(o->under_object, o->under_vol_id, cls, opt_type, flags);
 
     return ret_value;
 } /* end H5VL_pass_through_introspect_opt_query() */
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index bb4e60f..a020923 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -236,7 +236,7 @@ H5_DLL herr_t H5VL_object_optional(const H5VL_object_t *vol_obj, H5VL_object_opt
 H5_DLL herr_t H5VL_introspect_get_conn_cls(const H5VL_object_t *vol_obj, H5VL_get_conn_lvl_t lvl,
                                            const H5VL_class_t **conn_cls);
 H5_DLL herr_t H5VL_introspect_opt_query(const H5VL_object_t *vol_obj, H5VL_subclass_t subcls, int opt_type,
-                                        hbool_t *supported);
+                                        uint64_t *flags);
 
 /* Asynchronous functions */
 H5_DLL herr_t H5VL_request_wait(const H5VL_object_t *vol_obj, uint64_t timeout, H5ES_status_t *status);
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index 9c9d60a..7494586 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -49,6 +49,25 @@
  */
 #define H5_VOL_MAX 65535
 
+/* Flags to return from H5VLquery_optional API and 'opt_query' callbacks */
+/* Note: Operations which access multiple objects' data or metadata in a
+ *      container should be registered as file-level optional operations.
+ *      (e.g. "H5Dwrite_multi" takes a list of datasets to write data to, so
+ *      a VOL connector that implemented it should register it as an optional
+ *      file operation, and pass-through VOL connectors that are stacked above
+ *      the connector that registered it should assume that dataset elements
+ *      for _any_ dataset in the file could be written to)
+ */
+#define H5VL_OPT_QUERY_SUPPORTED       0x0001 /* VOL connector supports this operation */
+#define H5VL_OPT_QUERY_READ_DATA       0x0002 /* Operation reads data for object */
+#define H5VL_OPT_QUERY_WRITE_DATA      0x0004 /* Operation writes data for object */
+#define H5VL_OPT_QUERY_QUERY_METADATA  0x0008 /* Operation reads metadata for object */
+#define H5VL_OPT_QUERY_MODIFY_METADATA 0x0010 /* Operation modifies metadata for object */
+#define H5VL_OPT_QUERY_COLLECTIVE                                                                            \
+    0x0020 /* Operation is collective (operations without this flag are assumed to be independent) */
+#define H5VL_OPT_QUERY_NO_ASYNC  0x0040 /* Operation may NOT be executed asynchronously */
+#define H5VL_OPT_QUERY_MULTI_OBJ 0x0080 /* Operation involves multiple objects */
+
 /*******************/
 /* Public Typedefs */
 /*******************/
@@ -319,12 +338,12 @@ H5_DLL herr_t H5VLunregister_connector(hid_t connector_id);
  * \obj_id
  * \param[in] subcls VOL subclass
  * \param[in] opt_type Option type
- * \param[out] supported Flag
+ * \param[out] flags Operation flags
  * \return \herr_t
  *
  * \since 1.12.0
  */
-H5_DLL herr_t H5VLquery_optional(hid_t obj_id, H5VL_subclass_t subcls, int opt_type, hbool_t *supported);
+H5_DLL herr_t H5VLquery_optional(hid_t obj_id, H5VL_subclass_t subcls, int opt_type, uint64_t *flags);
 
 #ifdef __cplusplus
 }