VFD plugins (#602)

* Implement support for loading of Virtual File Drivers as plugins

Fix plugin caching for VOL connector and VFD plugins

Fix plugin iteration to skip paths that can't be opened

* Enable dynamic loading of VFDs with HDF5_DRIVER environment variable

* Temporarily disable error reporting during H5F_open double file open

* Default to using HDstat in h5_get_file_size for unknown VFDs

* Use macros for some environment variables that HDF5 interprets

* Update "null" and "ctl testing" VFDs

1 files changed, 33 insertions, 0 deletions

diff --git a/test/null_vfd_plugin.h b/test/null_vfd_plugin.h
new file mode 100644
index 0000000..7b7671f
--- /dev/null
+++ b/test/null_vfd_plugin.h
@@ -0,0 +1,33 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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://www.hdfgroup.org/licenses.               *
+ * 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 null testing VFD plugin.
+ */
+#ifndef H5FDnull_H
+#define H5FDnull_H
+
+#define H5FD_NULL      (H5FD_null_init())
+#define NULL_VFD_NAME  "null_vfd_plugin"
+#define NULL_VFD_VALUE ((H5FD_class_value_t)200)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+H5_DLL hid_t H5FD_null_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif