Add pass-through VOL connector

MANIFEST

@@ -896,6 +896,8 @@
 ./src/H5VLnative.c
 ./src/H5VLnative.h
 ./src/H5VLnative_private.h
+./src/H5VLpassthru.c
+./src/H5VLpassthru.h
 ./src/H5VLpkg.h
 ./src/H5VLprivate.h
 ./src/H5VLpublic.h

src/CMakeLists.txt

@@ -628,9 +628,11 @@ set (H5VL_SOURCES
     ${HDF5_SRC_DIR}/H5VLcallback.c
     ${HDF5_SRC_DIR}/H5VLint.c
     ${HDF5_SRC_DIR}/H5VLnative.c
+    ${HDF5_SRC_DIR}/H5VLpassthru.c
 )
 set (H5VL_HDRS
     ${HDF5_SRC_DIR}/H5VLnative.h
+    ${HDF5_SRC_DIR}/H5VLpassthru.h
     ${HDF5_SRC_DIR}/H5VLpublic.h
 )
 IDE_GENERATED_PROPERTIES ("H5VL" "${H5VL_HDRS}" "${H5VL_SOURCES}" )

src/H5VLpassthru.h

@@ -0,0 +1,46 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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:	The public header file for the pass-through VOL connector.
+ */
+
+#ifndef _H5VLpassthru_H
+#define _H5VLpassthru_H
+
+/* Identifier for the pass-through VOL connector */
+#define H5VL_PASSTHRU	(H5VL_pass_through_register())
+
+/* Characteristics of the pass-through VOL connector */
+#define H5VL_PASSTHRU_NAME        "pass_through"
+#define H5VL_PASSTHRU_VALUE       505           /* VOL connector ID */
+#define H5VL_PASSTHRU_VERSION     0
+
+/* Pass-through VOL connector info */
+typedef struct H5VL_pass_through_info_t {
+    hid_t under_vol_id;         /* VOL ID for under VOL */
+    void *under_vol_info;       /* VOL info for under VOL */
+} H5VL_pass_through_info_t;
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+H5_DLL hid_t H5VL_pass_through_register(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _H5VLpassthru_H */
+

src/Makefile.am

@@ -114,7 +114,7 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5Topaque.c \
         H5Torder.c \
         H5Tpad.c H5Tprecis.c H5Tstrpad.c H5Tvisit.c H5Tvlen.c H5TS.c \
-        H5VL.c H5VLcallback.c H5VLint.c H5VLnative.c \
+        H5VL.c H5VLcallback.c H5VLint.c H5VLnative.c H5VLpassthru.c \
         H5VM.c H5WB.c H5Z.c  \
         H5Zdeflate.c H5Zfletcher32.c H5Znbit.c H5Zshuffle.c \
         H5Zscaleoffset.c H5Zszip.c H5Ztrans.c
@@ -141,7 +141,7 @@ include_HEADERS = hdf5.h H5api_adpt.h H5overflow.h H5pubconf.h H5public.h H5vers
         H5MMpublic.h H5Opublic.h H5Ppublic.h \
         H5PLextern.h H5PLpublic.h \
         H5Rpublic.h H5Spublic.h H5Tpublic.h \
-        H5VLnative.h H5VLpublic.h H5Zpublic.h
+        H5VLnative.h H5VLpassthru.h H5VLpublic.h H5Zpublic.h
 
 # install libhdf5.settings in lib directory
 settingsdir=$(libdir)

src/hdf5.h

@@ -52,7 +52,8 @@
 #include "H5FDwindows.h"        /* Win32 I/O                                    */
 #endif
 
-/* Virtual object layer drivers */
-#include "H5VLnative.h"         /* Native VOL driver                        */
+/* Virtual object layer (VOL) connectors */
+#include "H5VLnative.h"         /* Native VOL connector                     */
+#include "H5VLpassthru.h"       /* Pass-through VOL connector               */
 
 #endif