Fix shutdown errors when using the HDF5_VOL_CONNECTOR environment

variable to set a dynamically loaded plugin as the default VOL
connector. Fixes HDFFV-11057

4 files changed, 28 insertions, 2 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index ff024c3..77cd88b 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -419,6 +419,18 @@ New Features
 
       (ADB - 2018/09/18, HDFFV-10332)
 
+    - Fix shutdown failure when using the HDF5_VOL_CONNECTOR environment variable
+
+      When using the HDF5_VOL_CONNECTOR environment variable to set an
+      alternative default VOL connector, if the VOL connector is a dynamically
+      loaded plugin, the library can experience segmentation faults at when
+      the library is closed. This is due to the library unloading the plugins
+      before the virtual object layer. When then the VOL shutdown occurs,
+      it will attempt to close the default VOL connector, however this will
+      fail since the plugins will already have been unloaded.
+
+      (DER - 2020/03/18, HDFFV-11057)
+
 
     Parallel Library:
     -----------------
diff --git a/src/H5.c b/src/H5.c
index 16c12cb..62a1c09 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -355,7 +355,9 @@ H5_term_library(void)
             pending += DOWN(Z);
             pending += DOWN(FD);
             pending += DOWN(VL);
-            pending += DOWN(PL);
+            /* Don't shut down the plugin code until all "pluggable" interfaces (Z, FD, PL) are shut down */
+            if(pending == 0)
+                pending += DOWN(PL);
             /* Don't shut down the error code until other APIs which use it are shut down */
             if(pending == 0)
                 pending += DOWN(E);
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 6572faa..861629f 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -273,7 +273,7 @@ H5VL_term_package(void)
         else {
             if(H5I_nmembers(H5I_VOL) > 0) {
                 /* Unregister all VOL connectors */
-                (void)H5I_clear_type(H5I_VOL, FALSE, FALSE);
+                (void)H5I_clear_type(H5I_VOL, TRUE, FALSE);
                 n++;
             } /* end if */
             else {
diff --git a/src/H5VLpassthru.c b/src/H5VLpassthru.c
index 8b3dc62..2cf470e 100644
--- a/src/H5VLpassthru.c
+++ b/src/H5VLpassthru.c
@@ -1591,6 +1591,10 @@ H5VL_pass_through_file_create(const char *name, unsigned flags, hid_t fcpl_id,
     /* Get copy of our VOL info from FAPL */
     H5Pget_vol_info(fapl_id, (void **)&info);
 
+    /* Make sure we have info about the underlying VOL to be used */
+    if (!info)
+        return NULL;
+
     /* Copy the FAPL */
     under_fapl_id = H5Pcopy(fapl_id);
 
@@ -1645,6 +1649,10 @@ H5VL_pass_through_file_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Get copy of our VOL info from FAPL */
     H5Pget_vol_info(fapl_id, (void **)&info);
 
+    /* Make sure we have info about the underlying VOL to be used */
+    if (!info)
+        return NULL;
+
     /* Copy the FAPL */
     under_fapl_id = H5Pcopy(fapl_id);
 
@@ -1785,6 +1793,10 @@ H5VL_pass_through_file_specific(void *file, H5VL_file_specific_t specific_type,
         /* Get copy of our VOL info from FAPL */
         H5Pget_vol_info(fapl_id, (void **)&info);
 
+        /* Make sure we have info about the underlying VOL to be used */
+        if (!info)
+            return (-1);
+
         /* Copy the FAPL */
         under_fapl_id = H5Pcopy(fapl_id);