Add an 'unwrap' VOL callback, so that connectors can unwrap an underlying

object without closing it.  (Especially needed for pass-through connectors)

1 files changed, 117 insertions, 48 deletions

diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index 03828fa..b785747 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -740,84 +740,89 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_free_wrap_ctx
+ * Function:    H5VL_wrap_object
  *
- * Purpose:     Free object wrapping context for a connector
+ * Purpose:     Wrap an object with connector
  *
- * Return:      Success:    Non-negative
- *              Failure:    Negative
+ * Return:      Success:    Non-NULL
+ *              Failure:    NULL
  *
  *-------------------------------------------------------------------------
  */
-herr_t
-H5VL_free_wrap_ctx(const H5VL_class_t *connector, void *wrap_ctx)
+void *
+H5VL_wrap_object(const H5VL_class_t *connector, void *wrap_ctx, void *obj,
+    H5I_type_t obj_type)
 {
-    herr_t ret_value = SUCCEED;   /* Return value */
+    void *ret_value;            /* Return value */
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_NOAPI(NULL)
 
     /* Sanity checks */
     HDassert(connector);
+    HDassert(obj);
 
-    /* Only free wrap context, if it's non-NULL */
+    /* Only wrap object if there's a wrap context */
     if(wrap_ctx) {
-        /* Free the connector's object wrapping context */
-        if((connector->wrap_cls.free_wrap_ctx)(wrap_ctx) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "connector wrap context free request failed")
+        /* Ask the connector to wrap the object */
+        if(NULL == (ret_value = (connector->wrap_cls.wrap_object)(obj, obj_type, wrap_ctx)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "can't wrap object")
     } /* end if */
+    else
+        ret_value = obj;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_free_wrap_ctx() */
+} /* end H5VL_wrap_object() */
 
 
 /*---------------------------------------------------------------------------
- * Function:    H5VLfree_wrap_ctx
+ * Function:    H5VLwrap_object
  *
- * Purpose:     Release a VOL connector's object wrapping context
+ * Purpose:     Asks a connector to wrap an underlying object.
  *
- * Return:      Success:    Non-negative
- *              Failure:    Negative
+ * Return:      Success:    Non-NULL
+ *              Failure:    NULL
  *
  *---------------------------------------------------------------------------
  */
-herr_t
-H5VLfree_wrap_ctx(void *wrap_ctx, hid_t connector_id)
+void *
+H5VLwrap_object(void *obj, H5I_type_t obj_type, hid_t connector_id, void *wrap_ctx)
 {
-    H5VL_class_t *cls;                  /* VOL connector's class struct */
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5VL_class_t *cls;          /* VOL connector's class struct */
+    void *ret_value = NULL;     /* Return value */
 
     FUNC_ENTER_API_NOINIT
-    H5TRACE2("e", "*xi", wrap_ctx, connector_id);
+    H5TRACE4("*x", "*xIti*x", obj, obj_type, connector_id, wrap_ctx);
 
     /* Check args and get class pointer */
+    if(NULL == obj)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
     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")
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL connector ID")
 
-    /* Release the VOL connector's object wrapper */
-    if(H5VL_free_wrap_ctx(cls, wrap_ctx) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to release VOL connector object wrap context")
+    /* Wrap the object */
+    if(NULL == (ret_value = H5VL_wrap_object(cls, wrap_ctx, obj, obj_type)))
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "unable to wrap object")
 
 done:
     FUNC_LEAVE_API_NOINIT(ret_value)
-} /* H5VLfree_wrap_ctx() */
+} /* H5VLwrap_object */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_wrap_object
+ * Function:    H5VL_unwrap_object
  *
- * Purpose:     Wrap an object with connector
+ * Purpose:     Unwrap an object from connector
  *
- * Return:      Success:    Non-negative
- *              Failure:    Negative
+ * Return:      Success:    Non-NULL
+ *              Failure:    NULL
  *
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_wrap_object(const H5VL_class_t *connector, void *wrap_ctx, void *obj,
-    H5I_type_t obj_type)
+H5VL_unwrap_object(const H5VL_class_t *connector, void *obj)
 {
-    void *ret_value = SUCCEED;   /* Return value */
+    void *ret_value;            /* Return value */
 
     FUNC_ENTER_NOAPI(NULL)
 
@@ -825,24 +830,24 @@ H5VL_wrap_object(const H5VL_class_t *connector, void *wrap_ctx, void *obj,
     HDassert(connector);
     HDassert(obj);
 
-    /* Only wrap object if there's a wrap context */
-    if(wrap_ctx) {
-        /* Ask the connector to wrap the object */
-        if(NULL == (ret_value = (connector->wrap_cls.wrap_object)(obj, obj_type, wrap_ctx)))
-            HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "can't wrap object")
+    /* Only unwrap object if there's an unwrap callback */
+    if(connector->wrap_cls.wrap_object) {
+        /* Ask the connector to unwrap the object */
+        if(NULL == (ret_value = (connector->wrap_cls.unwrap_object)(obj)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "can't unwrap object")
     } /* end if */
     else
         ret_value = obj;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_wrap_object() */
+} /* end H5VL_unwrap_object() */
 
 
 /*---------------------------------------------------------------------------
- * Function:    H5VLwrap_object
+ * Function:    H5VLunwrap_object
  *
- * Purpose:     Asks a connector to wrap an underlying object.
+ * Purpose:     Unwrap an object from connector
  *
  * Return:      Success:    Non-NULL
  *              Failure:    NULL
@@ -850,13 +855,13 @@ done:
  *---------------------------------------------------------------------------
  */
 void *
-H5VLwrap_object(void *obj, H5I_type_t obj_type, hid_t connector_id, void *wrap_ctx)
+H5VLunwrap_object(void *obj, hid_t connector_id)
 {
     H5VL_class_t *cls;          /* VOL connector's class struct */
     void *ret_value = NULL;     /* Return value */
 
     FUNC_ENTER_API_NOINIT
-    H5TRACE4("*x", "*xIti*x", obj, obj_type, connector_id, wrap_ctx);
+    H5TRACE2("*x", "*xi", obj, connector_id);
 
     /* Check args and get class pointer */
     if(NULL == obj)
@@ -864,13 +869,77 @@ H5VLwrap_object(void *obj, H5I_type_t obj_type, hid_t connector_id, void *wrap_c
     if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL connector ID")
 
-    /* Wrap the object */
-    if(NULL == (ret_value = H5VL_wrap_object(cls, wrap_ctx, obj, obj_type)))
-        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "unable to wrap object")
+    /* Unwrap the object */
+    if(NULL == (ret_value = H5VL_unwrap_object(cls, obj)))
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "unable to unwrap object")
 
 done:
     FUNC_LEAVE_API_NOINIT(ret_value)
-} /* H5VLwrap_object */
+} /* H5VLunwrap_object */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL_free_wrap_ctx
+ *
+ * Purpose:     Free object wrapping context for a connector
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_free_wrap_ctx(const H5VL_class_t *connector, void *wrap_ctx)
+{
+    herr_t ret_value = SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity checks */
+    HDassert(connector);
+
+    /* Only free wrap context, if it's non-NULL */
+    if(wrap_ctx) {
+        /* Free the connector's object wrapping context */
+        if((connector->wrap_cls.free_wrap_ctx)(wrap_ctx) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "connector wrap context free request failed")
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_free_wrap_ctx() */
+
+
+/*---------------------------------------------------------------------------
+ * Function:    H5VLfree_wrap_ctx
+ *
+ * Purpose:     Release a VOL connector's object wrapping context
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *---------------------------------------------------------------------------
+ */
+herr_t
+H5VLfree_wrap_ctx(void *wrap_ctx, hid_t connector_id)
+{
+    H5VL_class_t *cls;                  /* VOL connector's class struct */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API_NOINIT
+    H5TRACE2("e", "*xi", wrap_ctx, connector_id);
+
+    /* Check args and 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")
+
+    /* Release the VOL connector's object wrapper */
+    if(H5VL_free_wrap_ctx(cls, wrap_ctx) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to release VOL connector object wrap context")
+
+done:
+    FUNC_LEAVE_API_NOINIT(ret_value)
+} /* H5VLfree_wrap_ctx() */
 
 
 /*-------------------------------------------------------------------------