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, 14 insertions, 2 deletions

diff --git a/test/links_env.c b/test/links_env.c
index 590be20..7170132 100644
--- a/test/links_env.c
+++ b/test/links_env.c
@@ -152,8 +152,20 @@ error:
 int
 main(void)
 {
-    hid_t fapl;        /* File access property lists */
-    int   nerrors = 0; /* Error from tests */
+    const char *env_h5_drvr; /* File driver value from environment */
+    hid_t       fapl;        /* File access property lists */
+    int         nerrors = 0; /* Error from tests */
+
+    /* Get the VFD to use */
+    env_h5_drvr = HDgetenv(HDF5_DRIVER);
+    if (env_h5_drvr == NULL)
+        env_h5_drvr = "nomatch";
+
+    /* Splitter VFD has issues with external links */
+    if (!HDstrcmp(env_h5_drvr, "splitter")) {
+        HDputs(" -- SKIPPED for incompatible VFD --");
+        HDexit(EXIT_SUCCESS);
+    }
 
     h5_reset();
     fapl = h5_fileaccess();