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, 15 insertions, 1 deletions

diff --git a/test/dangle.c b/test/dangle.c
index d41507b..95d3105 100644
--- a/test/dangle.c
+++ b/test/dangle.c
@@ -660,7 +660,21 @@ error:
 int
 main(void)
 {
-    int nerrors = 0;
+    const char *env_h5_drvr; /* File Driver value from environment */
+    int         nerrors = 0;
+
+    /* Get the VFD to use */
+    env_h5_drvr = HDgetenv(HDF5_DRIVER);
+    if (env_h5_drvr == NULL)
+        env_h5_drvr = "nomatch";
+
+    /* Don't run this test with the multi/split VFD. A bug in library shutdown
+     * ordering causes problems with the multi VFD when IDs are left dangling.
+     */
+    if (!HDstrcmp(env_h5_drvr, "multi") || !HDstrcmp(env_h5_drvr, "split")) {
+        HDputs(" -- SKIPPED for incompatible VFD --");
+        return 0;
+    }
 
     /* Run tests w/weak file close */
     HDputs("Testing dangling objects with weak file close:");