Merge pull request #1813 in HDFFV/hdf5 from ~SONGYULU/hdf5_ray:feature/HDFFV-10658_properties_in_api_context to hdf5_1_10

* commit '64c17fd18b2649fe4f571b7c10a0b1cc82856af8':
  Updated the command for external_env and vds_env to the most recent changes.
  1. Updated the commands for compiling two new tests (external_env.c and vds_env.c). 2. Changed the data file names for external.c and external_env.c to avoid potential name conflict.
  HDFFV-10658: setting and getting properties in API context.  Porting the changes to the develop branch into the 1.10 branch: mainly the external file prefix and VDS prefix.

19 files changed, 1123 insertions, 475 deletions

diff --git a/MANIFEST b/MANIFEST
index 3040e1c..1d4ee06 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -975,6 +975,9 @@
 ./test/evict_on_close.c
 ./test/extend.c
 ./test/external.c
+./test/external_common.c
+./test/external_common.h
+./test/external_env.c
 ./test/error_test.c
 ./test/err_compat.c
 ./test/filter_error.h5
@@ -1097,6 +1100,7 @@
 ./test/tcoords.c
 ./test/testabort_fail.sh.in
 ./test/testcheck_version.sh.in
+./test/testexternal_env.sh.in
 ./test/testerror.sh.in
 ./test/testlinks_env.sh.in
 ./test/test_filter_plugin.sh.in
@@ -1109,6 +1113,7 @@
 ./test/testmeta.c
 ./test/testswmr.sh.in
 ./test/testvdsswmr.sh.in
+./test/testvds_env.sh.in
 ./test/tfile.c
 ./test/tgenprop.c
 ./test/th5o.c
@@ -1153,6 +1158,7 @@
 ./test/gen_filters.c
 ./test/chunk_info.c
 ./test/vds.c
+./test/vds_env.c
 ./test/vds_swmr.h
 ./test/vds_swmr_gen.c
 ./test/vds_swmr_reader.c
diff --git a/configure.ac b/configure.ac
index 6f6a91d..3c1e600 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3519,10 +3519,12 @@ AC_CONFIG_FILES([src/libhdf5.settings
                  test/testabort_fail.sh
                  test/testcheck_version.sh
                  test/testerror.sh
+                 test/testexternal_env.sh
                  test/testflushrefresh.sh
                  test/testlibinfo.sh
                  test/testlinks_env.sh
                  test/testswmr.sh
+                 test/testvds_env.sh
                  test/testvdsswmr.sh
                  test/test_filter_plugin.sh
                  test/test_usecases.sh
diff --git a/src/H5CX.c b/src/H5CX.c
index 7cf283a..01962a1 100644
--- a/src/H5CX.c
+++ b/src/H5CX.c
@@ -186,6 +186,10 @@ typedef struct H5CX_t {
     hid_t lapl_id;              /* LAPL ID for API operation */
     H5P_genplist_t *lapl;       /* Link Access Property List */
 
+    /* DAPL */
+    hid_t dapl_id;              /* DAPL ID for API operation */
+    H5P_genplist_t *dapl;       /* Dataset Access Property List */
+
     /* FAPL */
     hid_t fapl_id;              /* FAPL ID for API operation */
     H5P_genplist_t *fapl;       /* File Access Property List */
@@ -275,6 +279,12 @@ typedef struct H5CX_t {
     size_t nlinks;              /* Number of soft / UD links to traverse (H5L_ACS_NLINKS_NAME) */
     hbool_t nlinks_valid;       /* Whether number of soft / UD links to traverse is valid */
 
+    /* Cached DAPL properties */
+    char *extfile_prefix;               /* Prefix for external file                      */
+    hbool_t extfile_prefix_valid;       /* Whether the prefix for external file is valid */
+    char *vds_prefix;                   /* Prefix for VDS                                */
+    hbool_t vds_prefix_valid;           /* Whether the prefix for VDS is valid           */
+
     /* Cached FAPL properties */
     H5F_libver_t low_bound;     /* low_bound property for H5Pset_libver_bounds() */
     hbool_t low_bound_valid;    /* Whether low_bound property is valid */
@@ -329,6 +339,13 @@ typedef struct H5CX_lapl_cache_t {
     size_t nlinks;                  /* Number of soft / UD links to traverse (H5L_ACS_NLINKS_NAME) */
 } H5CX_lapl_cache_t;
 
+/* Typedef for cached default dataset access property list information */
+/* (Same as the cached DXPL struct, above, except for the default DXPL) */
+typedef struct H5CX_dapl_cache_t {
+    char *extfile_prefix;       /* Prefix for external file */
+    char *vds_prefix;           /* Prefix for VDS           */
+} H5CX_dapl_cache_t;
+
 /* Typedef for cached default file access property list information */
 /* (Same as the cached DXPL struct, above, except for the default DCPL) */
 typedef struct H5CX_fapl_cache_t {
@@ -367,6 +384,9 @@ static H5CX_dxpl_cache_t H5CX_def_dxpl_cache;
 /* Define a "default" link access property list cache structure to use for default LAPLs */
 static H5CX_lapl_cache_t H5CX_def_lapl_cache;
 
+/* Define a "default" dataset access property list cache structure to use for default DAPLs */
+static H5CX_dapl_cache_t H5CX_def_dapl_cache;
+
 /* Define a "default" file access property list cache structure to use for default FAPLs */
 static H5CX_fapl_cache_t H5CX_def_fapl_cache;
 
@@ -390,6 +410,7 @@ H5CX__init_package(void)
 {
     H5P_genplist_t *dx_plist;           /* Data transfer property list */
     H5P_genplist_t *la_plist;           /* Link access property list */
+    H5P_genplist_t *da_plist;           /* Dataset access property list */
     H5P_genplist_t *fa_plist;           /* File access property list */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -490,6 +511,23 @@ H5CX__init_package(void)
     if(H5P_get(la_plist, H5L_ACS_NLINKS_NAME, &H5CX_def_lapl_cache.nlinks) < 0)
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve number of soft / UD links to traverse")
 
+    /* Reset the "default DAPL cache" information */
+    HDmemset(&H5CX_def_dapl_cache, 0, sizeof(H5CX_dapl_cache_t));
+
+    /* Get the default DAPL cache information */
+
+    /* Get the default dataset access property list */
+    if(NULL == (da_plist = (H5P_genplist_t *)H5I_object(H5P_DATASET_ACCESS_DEFAULT)))
+        HGOTO_ERROR(H5E_CONTEXT, H5E_BADTYPE, FAIL, "not a dataset create property list")
+
+    /* Get the prefix for the external file */
+    if(H5P_peek(da_plist, H5D_ACS_EFILE_PREFIX_NAME, &H5CX_def_dapl_cache.extfile_prefix) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve prefix for external file")
+
+    /* Get the prefix for the VDS file */
+    if(H5P_peek(da_plist, H5D_ACS_VDS_PREFIX_NAME, &H5CX_def_dapl_cache.vds_prefix) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve prefix for VDS")
+
     /* Reset the "default FAPL cache" information */
     HDmemset(&H5CX_def_fapl_cache, 0, sizeof(H5CX_fapl_cache_t));
 
@@ -630,6 +668,7 @@ H5CX__push_common(H5CX_node_t *cnode)
     /* Set non-zero context info */
     cnode->ctx.dxpl_id = H5P_DATASET_XFER_DEFAULT;
     cnode->ctx.lapl_id = H5P_LINK_ACCESS_DEFAULT;
+    cnode->ctx.dapl_id = H5P_DATASET_ACCESS_DEFAULT;
     cnode->ctx.fapl_id = H5P_FILE_ACCESS_DEFAULT;
     cnode->ctx.tag = H5AC__INVALID_TAG;
     cnode->ctx.ring = H5AC_RING_USER;
@@ -867,6 +906,7 @@ H5CX_set_apl(hid_t *acspl_id, const H5P_libclass_t *libclass,
         *acspl_id = *libclass->def_plist_id;
     else {
         htri_t is_lapl;         /* Whether the access property list is (or is derived from) a link access property list */
+        htri_t is_dapl;         /* Whether the access property list is (or is derived from) a dataset access property list */
         htri_t is_fapl;         /* Whether the access property list is (or is derived from) a file access property list */
 
 #ifdef H5CX_DEBUG
@@ -881,6 +921,12 @@ H5CX_set_apl(hid_t *acspl_id, const H5P_libclass_t *libclass,
         else if(is_lapl)
             (*head)->ctx.lapl_id = *acspl_id;
 
+        /* Check for dataset access property and set API context if so */
+        if((is_dapl = H5P_class_isa(*libclass->pclass, *H5P_CLS_DACC->pclass)) < 0)
+            HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "can't check for dataset access class")
+        else if(is_dapl)
+            (*head)->ctx.dapl_id = *acspl_id;
+
         /* Check for file access property and set API context if so */
         if((is_fapl = H5P_class_isa(*libclass->pclass, *H5P_CLS_FACC->pclass)) < 0)
             HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "can't check for file access class")
@@ -1971,6 +2017,119 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5CX_get_libver_bounds() */
 
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_get_ext_file_prefix
+ *
+ * Purpose:     Retrieves the prefix for external file
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Raymond Lu
+ *              March 6, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_ext_file_prefix(char **extfile_prefix)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(extfile_prefix);
+    HDassert(head && *head);
+    HDassert(H5P_DEFAULT != (*head)->ctx.dapl_id);
+
+    /* Check if the value has been retrieved already */
+    if(!(*head)->ctx.extfile_prefix_valid) {
+        /* Check for default DAPL */
+        if((*head)->ctx.dapl_id == H5P_DATASET_ACCESS_DEFAULT)
+            (*head)->ctx.extfile_prefix = H5CX_def_dapl_cache.extfile_prefix;
+        else {
+            /* Check if the property list is already available */
+            if(NULL == (*head)->ctx.dapl)
+                /* Get the dataset access property list pointer */
+                if(NULL == ((*head)->ctx.dapl = (H5P_genplist_t *)H5I_object((*head)->ctx.dapl_id)))
+                    HGOTO_ERROR(H5E_CONTEXT, H5E_BADTYPE, FAIL, "can't get default dataset access property list")
+
+            /* Get the prefix for the external file */
+            /* (Note: 'peek', not 'get' - if this turns out to be a problem, we may need
+             *          to copy it and free this in the H5CX pop routine. -QAK)
+             */
+            if(H5P_peek((*head)->ctx.dapl, H5D_ACS_EFILE_PREFIX_NAME, &(*head)->ctx.extfile_prefix) < 0)
+                HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve external file prefix")
+        } /* end else */
+
+        /* Mark the value as valid */
+        (*head)->ctx.extfile_prefix_valid = TRUE;
+    } /* end if */
+
+    /* Get the value */
+    *extfile_prefix = (*head)->ctx.extfile_prefix;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_ext_file_prefix() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_get_vds_prefix
+ *
+ * Purpose:     Retrieves the prefix for VDS
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Raymond Lu
+ *              March 6, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_vds_prefix(char **vds_prefix)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(vds_prefix);
+    HDassert(head && *head);
+    HDassert(H5P_DEFAULT != (*head)->ctx.dapl_id);
+
+    /* Check if the value has been retrieved already */
+    if(!(*head)->ctx.vds_prefix_valid) {
+        /* Check for default DAPL */
+        if((*head)->ctx.dapl_id == H5P_DATASET_ACCESS_DEFAULT)
+            (*head)->ctx.vds_prefix = H5CX_def_dapl_cache.vds_prefix;
+        else {
+            /* Check if the property list is already available */
+            if(NULL == (*head)->ctx.dapl)
+                /* Get the dataset access property list pointer */
+                if(NULL == ((*head)->ctx.dapl = (H5P_genplist_t *)H5I_object((*head)->ctx.dapl_id)))
+                    HGOTO_ERROR(H5E_CONTEXT, H5E_BADTYPE, FAIL, "can't get default dataset access property list")
+
+            /* Get the prefix for the VDS */
+            /* (Note: 'peek', not 'get' - if this turns out to be a problem, we may need
+             *          to copy it and free this in the H5CX pop routine. -QAK)
+             */
+            if(H5P_peek((*head)->ctx.dapl, H5D_ACS_VDS_PREFIX_NAME, &(*head)->ctx.vds_prefix) < 0)
+                HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve VDS prefix")
+        } /* end else */
+
+        /* Mark the value as valid */
+        (*head)->ctx.vds_prefix_valid = TRUE;
+    } /* end if */
+
+    /* Get the value */
+    *vds_prefix = (*head)->ctx.vds_prefix;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_vds_prefix() */
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5CX_set_tag
diff --git a/src/H5CXprivate.h b/src/H5CXprivate.h
index 6c01119..d67f226 100644
--- a/src/H5CXprivate.h
+++ b/src/H5CXprivate.h
@@ -102,6 +102,10 @@ H5_DLL herr_t H5CX_get_dt_conv_cb(H5T_conv_cb_t *cb_struct);
 /* "Getter" routines for LAPL properties cached in API context */
 H5_DLL herr_t H5CX_get_nlinks(size_t *nlinks);
 
+/* "Getter" routines for DAPL properties cached in API context */
+H5_DLL herr_t H5CX_get_ext_file_prefix(char **prefix_extfile);
+H5_DLL herr_t H5CX_get_vds_prefix(char **prefix_vds);
+
 /* "Getter" routines for FAPL properties cached in API context */
 H5_DLL herr_t H5CX_get_libver_bounds(H5F_libver_t *low_bound, H5F_libver_t *high_bound);
 
diff --git a/src/H5Defl.c b/src/H5Defl.c
index 42b3947..ce0bb80 100644
--- a/src/H5Defl.c
+++ b/src/H5Defl.c
@@ -477,7 +477,6 @@ H5D__efl_readvv(const H5D_io_info_t *io_info,
     HDassert(io_info->u.rbuf);
     HDassert(io_info->dset);
     HDassert(io_info->dset->shared);
-    HDassert(io_info->dset->shared->extfile_prefix);
     HDassert(dset_curr_seq);
     HDassert(dset_len_arr);
     HDassert(dset_off_arr);
@@ -561,7 +560,6 @@ H5D__efl_writevv(const H5D_io_info_t *io_info,
     HDassert(io_info->u.wbuf);
     HDassert(io_info->dset);
     HDassert(io_info->dset->shared);
-    HDassert(io_info->dset->shared->extfile_prefix);
     HDassert(dset_curr_seq);
     HDassert(dset_len_arr);
     HDassert(dset_off_arr);
diff --git a/src/H5Dint.c b/src/H5Dint.c
index d3cad8f..a54333f 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -54,8 +54,8 @@ static herr_t H5D__init_type(H5F_t *file, const H5D_t *dset, hid_t type_id,
 static herr_t H5D__cache_dataspace_info(const H5D_t *dset);
 static herr_t H5D__init_space(H5F_t *file, const H5D_t *dset, const H5S_t *space);
 static herr_t H5D__update_oh_info(H5F_t *file, H5D_t *dset, hid_t dapl_id);
-static herr_t H5D__build_file_prefix(const H5D_t *dset, hid_t dapl_id,
-    const char *prefix_type, char **file_prefix);
+static herr_t H5D__build_file_prefix(const H5D_t *dset, H5F_prefix_open_t prefix_type,
+    char **file_prefix);
 static herr_t H5D__open_oid(H5D_t *dataset, hid_t dapl_id);
 static herr_t H5D__init_storage(const H5D_io_info_t *io_info, hbool_t full_overwrite,
         hsize_t old_dim[]);
@@ -112,6 +112,10 @@ static const H5I_class_t H5I_DATASET_CLS[1] = {{
 /* Flag indicating "top" of interface has been initialized */
 static hbool_t H5D_top_package_initialize_s = FALSE;
 
+/* Prefixes of VDS and external file from the environment variables
+ * HDF5_EXTFILE_PREFIX and HDF5_VDS_PREFIX */
+const static char *H5D_prefix_ext_env = NULL;
+const static char *H5D_prefix_vds_env = NULL;
 
 
 /*-------------------------------------------------------------------------
@@ -188,6 +192,10 @@ H5D__init_package(void)
     /* Mark "top" of interface as initialized, too */
     H5D_top_package_initialize_s = TRUE;
 
+    /* Retrieve the prefixes of VDS and external file from the environment variable */
+    H5D_prefix_vds_env = HDgetenv("HDF5_VDS_PREFIX");
+    H5D_prefix_ext_env = HDgetenv("HDF5_EXTFILE_PREFIX");
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__init_package() */
@@ -1045,8 +1053,7 @@ done:
  *--------------------------------------------------------------------------
  */
 static herr_t
-H5D__build_file_prefix(const H5D_t *dset, hid_t dapl_id, const char *prefix_type,
-    char **file_prefix /*out*/)
+H5D__build_file_prefix(const H5D_t *dset, H5F_prefix_open_t prefix_type, char **file_prefix /*out*/)
 {
     char            *prefix = NULL;       /* prefix used to look for the file               */
     char            *filepath = NULL;     /* absolute path of directory the HDF5 file is in */
@@ -1067,20 +1074,22 @@ H5D__build_file_prefix(const H5D_t *dset, hid_t dapl_id, const char *prefix_type
     /* XXX: Future thread-safety note - getenv is not required
      *      to be reentrant.
      */
-    if(HDstrcmp(prefix_type, H5D_ACS_VDS_PREFIX_NAME) == 0)
-        prefix = HDgetenv("HDF5_VDS_PREFIX");
-    else if (HDstrcmp(prefix_type, H5D_ACS_EFILE_PREFIX_NAME) == 0)
-        prefix = HDgetenv("HDF5_EXTFILE_PREFIX");
-    else
-        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "prefix name is not sensible")
-
-    if(prefix == NULL || *prefix == '\0') {
-        /* Set prefix to value of prefix_type property */
-        if(NULL == (plist = H5P_object_verify(dapl_id, H5P_DATASET_ACCESS)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
-        if(H5P_peek(plist, prefix_type, &prefix) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get file prefix")
-    } /* end if */
+    if(H5F_PREFIX_VDS == prefix_type) {
+        prefix = (char *)H5D_prefix_vds_env;
+
+        if(prefix == NULL || *prefix == '\0') {
+            if(H5CX_get_vds_prefix(&prefix) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get the prefix for vds file")
+        }
+    } else if(H5F_PREFIX_EFILE == prefix_type) {
+        prefix = (char *)H5D_prefix_ext_env;
+
+        if(prefix == NULL || *prefix == '\0') {
+            if(H5CX_get_ext_file_prefix(&prefix) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get the prefix for the external file")
+        }
+    } else
+        HGOTO_ERROR(H5E_DATASET, H5E_BADTYPE, FAIL, "prefix name is not sensible")
 
     /* Prefix has to be checked for NULL / empty string again because the
      * code above might have updated it.
@@ -1089,8 +1098,7 @@ H5D__build_file_prefix(const H5D_t *dset, hid_t dapl_id, const char *prefix_type
         /* filename is interpreted as relative to the current directory,
          * does not need to be expanded
          */
-        if(NULL == (*file_prefix = (char *)H5MM_strdup("")))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+        *file_prefix = NULL;
     } /* end if */
     else {
         if (HDstrncmp(prefix, "${ORIGIN}", HDstrlen("${ORIGIN}")) == 0) {
@@ -1285,11 +1293,11 @@ H5D__create(H5F_t *file, hid_t type_id, const H5S_t *space, hid_t dcpl_id,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to set up flush append property")
 
     /* Set the external file prefix */
-    if(H5D__build_file_prefix(new_dset, dapl_id, H5D_ACS_EFILE_PREFIX_NAME, &new_dset->shared->extfile_prefix) < 0)
+    if(H5D__build_file_prefix(new_dset, H5F_PREFIX_EFILE, &new_dset->shared->extfile_prefix) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize external file prefix")
 
     /* Set the VDS file prefix */
-    if(H5D__build_file_prefix(new_dset, dapl_id, H5D_ACS_VDS_PREFIX_NAME, &new_dset->shared->vds_prefix) < 0)
+    if(H5D__build_file_prefix(new_dset, H5F_PREFIX_VDS, &new_dset->shared->vds_prefix) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize VDS prefix")
 
     /* Add the dataset to the list of opened objects in the file */
@@ -1444,11 +1452,11 @@ H5D_open(const H5G_loc_t *loc, hid_t dapl_id)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, NULL, "can't copy path")
 
     /* Get the external file prefix */
-    if(H5D__build_file_prefix(dataset, dapl_id, H5D_ACS_EFILE_PREFIX_NAME, &extfile_prefix) < 0)
+    if(H5D__build_file_prefix(dataset, H5F_PREFIX_EFILE, &extfile_prefix) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize external file prefix")
 
     /* Get the VDS prefix */
-    if(H5D__build_file_prefix(dataset, dapl_id, H5D_ACS_VDS_PREFIX_NAME, &vds_prefix) < 0)
+    if(H5D__build_file_prefix(dataset, H5F_PREFIX_VDS, &vds_prefix) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize VDS prefix")
 
     /* Check if dataset was already open */
@@ -1492,8 +1500,13 @@ H5D_open(const H5G_loc_t *loc, hid_t dapl_id)
         /* Check whether the external file prefix of the already open dataset
          * matches the new external file prefix
          */
-        if(HDstrcmp(extfile_prefix, dataset->shared->extfile_prefix) != 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        if(extfile_prefix && dataset->shared->extfile_prefix) {
+            if(HDstrcmp(extfile_prefix, dataset->shared->extfile_prefix) != 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        } else {
+            if(extfile_prefix || dataset->shared->extfile_prefix)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        }
 
         /* Check if the object has been opened through the top file yet */
         if(H5FO_top_count(dataset->oloc.file, dataset->oloc.addr) == 0) {
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index d60c08f..5e78d9e 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -702,8 +702,9 @@ typedef enum H5F_mem_page_t {
 
 /* Type of prefix for opening prefixed files */
 typedef enum H5F_prefix_open_t {
-    H5F_PREFIX_VDS,             /* Virtual dataset prefix */
-    H5F_PREFIX_ELINK            /* External link prefix */
+    H5F_PREFIX_VDS   = 0,           /* Virtual dataset prefix */
+    H5F_PREFIX_ELINK = 1,           /* External link prefix   */
+    H5F_PREFIX_EFILE = 2            /* External file prefix   */
 } H5F_prefix_open_t;
 
 
diff --git a/src/H5system.c b/src/H5system.c
index 186d8fa..41e2a48 100644
--- a/src/H5system.c
+++ b/src/H5system.c
@@ -1125,13 +1125,13 @@ H5_combine_path(const char* path1, const char* path2, char **full_name /*out*/)
 
     FUNC_ENTER_NOAPI_NOINIT
 
-    HDassert(path1);
     HDassert(path2);
 
-    path1_len = HDstrlen(path1);
+    if(path1)
+        path1_len = HDstrlen(path1);
     path2_len = HDstrlen(path2);
 
-    if(*path1 == '\0' || H5_CHECK_ABSOLUTE(path2)) {
+    if(path1 == NULL || *path1 == '\0' || H5_CHECK_ABSOLUTE(path2)) {
 
         /* If path1 is empty or path2 is absolute, simply use path2 */
         if(NULL == (*full_name = (char *)H5MM_strdup(path2)))
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 5b34ec5..f5a6b60 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -14,12 +14,14 @@ set (TEST_LIB_SOURCES
     ${HDF5_TEST_SOURCE_DIR}/h5test.c
     ${HDF5_TEST_SOURCE_DIR}/testframe.c
     ${HDF5_TEST_SOURCE_DIR}/cache_common.c
+    ${HDF5_TEST_SOURCE_DIR}/external_common.c
     ${HDF5_TEST_SOURCE_DIR}/swmr_common.c
 )
 
 set (TEST_LIB_HEADERS
     ${HDF5_TEST_SOURCE_DIR}/h5test.h
     ${HDF5_TEST_SOURCE_DIR}/cache_common.h
+    ${HDF5_TEST_SOURCE_DIR}/external_common.h
     ${HDF5_TEST_SOURCE_DIR}/swmr_common.h
 )
 
@@ -208,6 +210,7 @@ set (H5_TESTS
     extend
     direct_chunk # compression lib link
     external
+    external_env
     efc
     objcopy
     links
@@ -235,6 +238,7 @@ set (H5_TESTS
     freespace
     mf
     vds
+    vds_env
     file_image
     unregister
     cache_logging
diff --git a/test/CMakeTests.cmake b/test/CMakeTests.cmake
index fe6c695..07f840a 100644
--- a/test/CMakeTests.cmake
+++ b/test/CMakeTests.cmake
@@ -463,8 +463,10 @@ set (H5TEST_SEPARATE_TESTS
     testhdf5
     cache
     cache_image
+    external_env
     flush1
     flush2
+    vds_env
 )
 foreach (h5_test ${H5_TESTS})
   if (NOT h5_test IN_LIST H5TEST_SEPARATE_TESTS)
@@ -787,6 +789,79 @@ set_tests_properties (H5TEST-links_env PROPERTIES
     WORKING_DIRECTORY ${HDF5_TEST_BINARY_DIR}/H5TEST
 )
 
+#-- Adding test for external_env
+add_test (
+    NAME H5TEST-external_env-clear-objects
+    COMMAND ${CMAKE_COMMAND} -E remove
+        extern_env_1r.raw
+        extern_env_2r.raw
+        extern_env_3r.raw
+        extern_env_4r.raw
+        extern_env_1w.raw
+        extern_env_2w.raw
+        extern_env_3w.raw
+        extern_env_4w.raw
+    WORKING_DIRECTORY
+        ${HDF5_TEST_BINARY_DIR}/H5TEST
+)
+set_tests_properties (H5TEST-external_env-clear-objects PROPERTIES FIXTURES_SETUP clear_external_env)
+if (HDF5_ENABLE_USING_MEMCHECKER)
+  add_test (NAME H5TEST-external_env COMMAND ${CMAKE_CROSSCOMPILING_EMULATOR} $<TARGET_FILE:external_env>)
+else ()
+  add_test (NAME H5TEST-external_env COMMAND "${CMAKE_COMMAND}"
+        -D "TEST_EMULATOR=${CMAKE_CROSSCOMPILING_EMULATOR}"
+        -D "TEST_PROGRAM=$<TARGET_FILE:external_env>"
+        -D "TEST_ARGS:STRING="
+        -D "TEST_ENV_VAR:STRING=HDF5_EXTFILE_PREFIX"
+        -D "TEST_ENV_VALUE:STRING=\${ORIGIN}"
+        -D "TEST_EXPECT=0"
+        -D "TEST_SKIP_COMPARE=TRUE"
+        -D "TEST_OUTPUT=external_env.txt"
+        #-D "TEST_REFERENCE=external_env.out"
+        -D "TEST_FOLDER=${PROJECT_BINARY_DIR}/H5TEST"
+        -P "${HDF_RESOURCES_EXT_DIR}/runTest.cmake"
+  )
+endif ()
+set_tests_properties (H5TEST-external_env PROPERTIES
+    FIXTURES_REQUIRED clear_external_env
+    ENVIRONMENT "srcdir=${HDF5_TEST_BINARY_DIR}/H5TEST;HDF5TestExpress=${HDF_TEST_EXPRESS}"
+    WORKING_DIRECTORY ${HDF5_TEST_BINARY_DIR}/H5TEST
+)
+
+#-- Adding test for vds_env
+add_test (
+    NAME H5TEST-vds_env-clear-objects
+    COMMAND ${CMAKE_COMMAND} -E remove
+        vds_virt_0.h5
+        vds_virt_3.h5
+        vds_src_2.h5
+    WORKING_DIRECTORY
+        ${HDF5_TEST_BINARY_DIR}/H5TEST
+)
+set_tests_properties (H5TEST-vds_env-clear-objects PROPERTIES FIXTURES_SETUP clear_vds_env)
+if (HDF5_ENABLE_USING_MEMCHECKER)
+  add_test (NAME H5TEST-vds_env COMMAND ${CMAKE_CROSSCOMPILING_EMULATOR} $<TARGET_FILE:vds_env>)
+else ()
+  add_test (NAME H5TEST-vds_env COMMAND "${CMAKE_COMMAND}"
+        -D "TEST_EMULATOR=${CMAKE_CROSSCOMPILING_EMULATOR}"
+        -D "TEST_PROGRAM=$<TARGET_FILE:vds_env>"
+        -D "TEST_ARGS:STRING="
+        -D "TEST_ENV_VAR:STRING=HDF5_VDS_PREFIX"
+        -D "TEST_ENV_VALUE:STRING=\${ORIGIN}/tmp"
+        -D "TEST_EXPECT=0"
+        -D "TEST_SKIP_COMPARE=TRUE"
+        -D "TEST_OUTPUT=vds_env.txt"
+        #-D "TEST_REFERENCE=vds_env.out"
+        -D "TEST_FOLDER=${PROJECT_BINARY_DIR}/H5TEST"
+        -P "${HDF_RESOURCES_EXT_DIR}/runTest.cmake"
+  )
+endif ()
+set_tests_properties (H5TEST-vds_env PROPERTIES
+    FIXTURES_REQUIRED clear_vds_env
+    ENVIRONMENT "srcdir=${HDF5_TEST_BINARY_DIR}/H5TEST;HDF5TestExpress=${HDF_TEST_EXPRESS}"
+    WORKING_DIRECTORY ${HDF5_TEST_BINARY_DIR}/H5TEST
+)
+
 if (NOT BUILD_SHARED_LIBS)
   #-- Adding test for libinfo
   add_test (NAME H5TEST-testlibinfo
diff --git a/test/Makefile.am b/test/Makefile.am
index c4fb876..dce2f98 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -26,21 +26,23 @@ AM_CPPFLAGS+=-I$(top_srcdir)/src -I$(top_builddir)/src
 #       testlibinfo.sh:
 #       testcheck_version.sh: tcheck_version
 #       testlinks_env.sh: links_env
+#       testexternal_env.sh: external_env
 #       testflushrefresh.sh: flushrefresh
+#       testvds_env.sh: vds_env
 #       testswmr.sh: swmr*
 #       testvdsswmr.sh: vds_swmr*
 #       testabort_fail.sh: filenotclosed.c and del_many_dense_attrs.c
 #       test_filter_plugin.sh: filter_plugin.c
 #       test_usecases.sh: use_append_chunk, use_append_mchunks, use_disable_mdc_flushes
-TEST_SCRIPT = testerror.sh testlibinfo.sh testcheck_version.sh testlinks_env.sh \
-    testswmr.sh testvdsswmr.sh testflushrefresh.sh test_usecases.sh testabort_fail.sh
+TEST_SCRIPT = testerror.sh testlibinfo.sh testcheck_version.sh testlinks_env.sh testexternal_env.sh \
+    testswmr.sh testvds_env.sh testvdsswmr.sh testflushrefresh.sh test_usecases.sh testabort_fail.sh
 SCRIPT_DEPEND = error_test$(EXEEXT) err_compat$(EXEEXT) links_env$(EXEEXT) \
     filenotclosed$(EXEEXT) del_many_dense_attrs$(EXEEXT) \
-    flushrefresh$(EXEEXT) use_append_chunk$(EXEEXT) use_append_mchunks$(EXEEXT) use_disable_mdc_flushes$(EXEEXT) \
+    external_env$(EXEEXT) flushrefresh$(EXEEXT) use_append_chunk$(EXEEXT) use_append_mchunks$(EXEEXT) use_disable_mdc_flushes$(EXEEXT) \
     swmr_generator$(EXEEXT) swmr_reader$(EXEEXT) swmr_writer$(EXEEXT) \
     swmr_remove_reader$(EXEEXT) swmr_remove_writer$(EXEEXT) swmr_addrem_writer$(EXEEXT) \
     swmr_sparse_reader$(EXEEXT) swmr_sparse_writer$(EXEEXT) swmr_start_write$(EXEEXT) \
-    vds_swmr_gen$(EXEEXT) vds_swmr_reader$(EXEEXT) vds_swmr_writer$(EXEEXT)
+    vds_env$(EXEEXT) vds_swmr_gen$(EXEEXT) vds_swmr_reader$(EXEEXT) vds_swmr_writer$(EXEEXT)
 if HAVE_SHARED_CONDITIONAL
   TEST_SCRIPT += test_filter_plugin.sh
   SCRIPT_DEPEND += filter_plugin$(EXEEXT)
@@ -69,21 +71,23 @@ TEST_PROG= testhdf5 \
 # accum_swmr_reader is used by accum.c.
 # atomic_writer and atomic_reader are standalone programs.
 # links_env is used by testlinks_env.sh
+# external_env is used by testexternal_env.sh
 # filenotclosed and del_many_dense_attrs are used by testabort_fail.sh
 # flushrefresh is used by testflushrefresh.sh.
 # use_append_chunk, use_append_mchunks and use_disable_mdc_flushes are used by test_usecases.sh
 # swmr_* files (besides swmr.c) are used by testswmr.sh.
 # vds_swmr_* files are used by testvdsswmr.sh
+# vds_env is used by testvds_env.sh
 # 'make check' doesn't run them directly, so they are not included in TEST_PROG.
 # Also build testmeta, which is used for timings test.  It builds quickly,
 # and this lets automake keep all its test programs in one place.
 check_PROGRAMS=$(TEST_PROG) error_test err_compat tcheck_version \
-    testmeta accum_swmr_reader atomic_writer atomic_reader \
+    testmeta accum_swmr_reader atomic_writer atomic_reader external_env \
     links_env filenotclosed del_many_dense_attrs flushrefresh \
     use_append_chunk use_append_mchunks use_disable_mdc_flushes \
     swmr_generator swmr_start_write swmr_reader swmr_writer swmr_remove_reader \
     swmr_remove_writer swmr_addrem_writer swmr_sparse_reader swmr_sparse_writer \
-    swmr_check_compat_vfd vds_swmr_gen vds_swmr_reader vds_swmr_writer
+    swmr_check_compat_vfd vds_swmr_gen vds_env vds_swmr_reader vds_swmr_writer
 if HAVE_SHARED_CONDITIONAL
   check_PROGRAMS+= filter_plugin
 endif
@@ -124,7 +128,7 @@ else
   noinst_LTLIBRARIES=libh5test.la
 endif
 
-libh5test_la_SOURCES=h5test.c testframe.c cache_common.c swmr_common.c
+libh5test_la_SOURCES=h5test.c testframe.c cache_common.c swmr_common.c external_common.c
 
 # Use libhd5test.la to compile all of the tests
 LDADD=libh5test.la $(LIBHDF5)
@@ -211,6 +215,6 @@ use_disable_mdc_flushes_SOURCES=use_disable_mdc_flushes.c
 
 # Temporary files.
 DISTCLEANFILES=testerror.sh testlibinfo.sh testcheck_version.sh testlinks_env.sh test_filter_plugin.sh \
-    testswmr.sh testvdsswmr.sh test_usecases.sh testflushrefresh.sh testabort_fail.sh
+    testexternal_env.sh testswmr.sh testvds_env.sh testvdsswmr.sh test_usecases.sh testflushrefresh.sh testabort_fail.sh
 
 include $(top_srcdir)/config/conclude.am
diff --git a/test/external.c b/test/external.c
index 20a9ed8..7e9ecf9 100644
--- a/test/external.c
+++ b/test/external.c
@@ -18,24 +18,7 @@
  * Purpose:	Tests datasets stored in external raw files.
  */
 #include "h5test.h"
-
-const char *FILENAME[] = {
-    "extern_1",
-    "extern_2",
-    "extern_3",
-    "extern_4",
-    "extern_dir/file_1",
-    "extern_5",
-    NULL
-};
-
-/* A similar collection of files is used for the tests that
- * perform file I/O.
- */
-#define N_EXT_FILES         4
-#define PART_SIZE           25
-#define TOTAL_SIZE          100
-#define GARBAGE_PER_FILE    10
+#include "external_common.h"
 
 
 /*-------------------------------------------------------------------------
@@ -99,106 +82,6 @@ out:
 
 
 /*-------------------------------------------------------------------------
- * Function:    reset_raw_data_files
- *
- * Purpose:     Resets the data in the raw data files for tests that
- *              perform dataset I/O on a set of files.
- *
- * Return:      SUCCEED/FAIL
- *
- * Programmer:  Dana Robinson
- *              February 2016
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-reset_raw_data_files(void)
-{
-    int		    fd = 0;             /* external file descriptor             */
-    size_t	    i, j;               /* iterators                            */
-    hssize_t	n;                  /* bytes of I/O                         */
-    char	    filename[1024];     /* file name                            */
-    int		    data[PART_SIZE];    /* raw data buffer                      */
-    uint8_t     *garbage = NULL;    /* buffer of garbage data               */
-    size_t      garbage_count;      /* size of garbage buffer               */
-    size_t      garbage_bytes;      /* # of garbage bytes written to file   */
-
-    /* Set up garbage buffer */
-    garbage_count = N_EXT_FILES * GARBAGE_PER_FILE;
-    if(NULL == (garbage = (uint8_t *)HDcalloc(garbage_count, sizeof(uint8_t))))
-        goto error;
-    for(i = 0; i < garbage_count; i++)
-        garbage[i] = 0xFF;
-
-    /* The *r files are pre-filled with data and are used to
-     * verify that read operations work correctly.
-     */
-    for(i = 0; i < N_EXT_FILES; i++) {
-
-        /* Open file */
-        HDsprintf(filename, "extern_%lur.raw", (unsigned long)i + 1);
-        if((fd = HDopen(filename, O_RDWR|O_CREAT|O_TRUNC, H5_POSIX_CREATE_MODE_RW)) < 0)
-            goto error;
-        
-        /* Write garbage data to the file. This allows us to test the
-         * the ability to set an offset in the raw data file.
-         */
-        garbage_bytes = i * 10;
-        n = HDwrite(fd, garbage, garbage_bytes);
-        if(n < 0 || (size_t)n != garbage_bytes)
-            goto error;
-
-        /* Fill array with data */
-        for(j = 0; j < PART_SIZE; j++) {
-            data[j] = (int)(i * 25 + j);
-        } /* end for */
-
-        /* Write raw data to the file. */
-        n = HDwrite(fd, data, sizeof(data));
-        if(n != sizeof(data))
-            goto error;
-
-        /* Close this file */
-        HDclose(fd);
-
-    } /* end for */
-
-    /* The *w files are only pre-filled with the garbage data and are
-     * used to verify that write operations work correctly. The individual
-     * tests fill in the actual data.
-     */
-    for(i = 0; i < N_EXT_FILES; i++) {
-
-        /* Open file */
-        HDsprintf(filename, "extern_%luw.raw", (unsigned long)i + 1);
-        if((fd = HDopen(filename, O_RDWR|O_CREAT|O_TRUNC, H5_POSIX_CREATE_MODE_RW)) < 0)
-            goto error;
-        
-        /* Write garbage data to the file. This allows us to test the
-         * the ability to set an offset in the raw data file.
-         */
-        garbage_bytes = i * 10;
-        n = HDwrite(fd, garbage, garbage_bytes);
-        if(n < 0 || (size_t)n != garbage_bytes)
-            goto error;
-
-        /* Close this file */
-        HDclose(fd);
-
-    } /* end for */
-    HDfree(garbage);
-    return SUCCEED;
-
-error:
-    if(fd)
-        HDclose(fd);
-    if(garbage)
-        HDfree(garbage);
-    return FAIL;
-} /* end reset_raw_data_files() */
-
-
-/*-------------------------------------------------------------------------
  * Function:    test_non_extendible
  *
  * Purpose:     Tests a non-extendible dataset with a single external file.
@@ -753,14 +636,14 @@ test_read_file_set(hid_t fapl)
         TEST_ERROR
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the file and an initial group.  This causes messages about
      * debugging to be emitted before we start playing games with what the
      * output looks like.
      */
-    h5_fixname(FILENAME[1], fapl, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[1], fapl, filename, sizeof(filename));
     if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
         FAIL_STACK_ERROR
     if((grp = H5Gcreate2(file, "emit-diagnostics", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
@@ -871,7 +754,7 @@ test_write_file_set(hid_t fapl)
         TEST_ERROR
 
     /* Create another file */
-    h5_fixname(FILENAME[2], fapl, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[2], fapl, filename, sizeof(filename));
     if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
         FAIL_STACK_ERROR
 
@@ -893,7 +776,7 @@ test_write_file_set(hid_t fapl)
     } /* end for */
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the dataset */
@@ -989,12 +872,12 @@ test_path_absolute(hid_t fapl)
 
     TESTING("absolute filenames for external file");
 
-    h5_fixname(FILENAME[3], fapl, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[3], fapl, filename, sizeof(filename));
     if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
         FAIL_STACK_ERROR
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the dcpl */
@@ -1085,12 +968,12 @@ test_path_relative(hid_t fapl)
     if (HDmkdir("extern_dir", (mode_t)0755) < 0 && errno != EEXIST)
         TEST_ERROR;
 
-    h5_fixname(FILENAME[4], fapl, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[4], fapl, filename, sizeof(filename));
     if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
         FAIL_STACK_ERROR;
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the dataset */
@@ -1180,12 +1063,12 @@ test_path_relative_cwd(hid_t fapl)
     if(HDmkdir("extern_dir", (mode_t)0755) < 0 && errno != EEXIST)
         TEST_ERROR;
 
-    h5_fixname(FILENAME[4], fapl, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[4], fapl, filename, sizeof(filename));
     if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
         FAIL_STACK_ERROR;
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the dataset */
@@ -1297,116 +1180,6 @@ error:
 
 
 /*-------------------------------------------------------------------------
- * Function:    test_path_env
- *
- * Purpose:     Test whether the value of HDF5_EXTFILE_PREFIX will overwrite
- *              the efile_prefix dataset access property.
- *              This will create an HDF5 file in a subdirectory which will
- *              refer to ../extern_*a.raw
- *              The files are then accessed by setting the HDF5_EXTFILE_PREFIX
- *              environment variable to "${ORIGIN}".
- *              The efile_prefix dataset access property is set to "someprefix",
- *              which will cause an error if the value is not overwritten by
- *              the environment variable.
- *
- * Return:      Success:    0
- *              Failure:    1
- *
- * Programmer:  Steffen Kiess
- *              March 10, 2015
- *
- *-------------------------------------------------------------------------
- */
-static int
-test_path_env(hid_t fapl)
-{
-    hid_t	file = -1;          /* file to write to                     */
-    hid_t	dcpl = -1;          /* dataset creation properties          */
-    hid_t	space = -1;         /* data space                           */
-    hid_t	dapl = -1;          /* dataset access property list         */
-    hid_t	dset = -1;          /* dataset                              */
-    size_t	i;                  /* miscellaneous counters               */
-    char	cwdpath[1024];		/* working directory                    */
-    char	filename[1024];		/* file name                            */
-    int	    part[PART_SIZE];    /* raw data buffer (partial)            */
-    int     whole[TOTAL_SIZE];  /* raw data buffer (total)              */
-    hsize_t	cur_size;           /* current data space size              */
-    char	buffer[1024];       /* buffer to read efile_prefix          */
-
-    TESTING("prefix in HDF5_EXTFILE_PREFIX");
-
-    if(HDsetenv("HDF5_EXTFILE_PREFIX", "${ORIGIN}", 1))
-        TEST_ERROR
-
-    if(HDmkdir("extern_dir", (mode_t)0755) < 0 && errno != EEXIST)
-        TEST_ERROR;
-
-    h5_fixname(FILENAME[4], fapl, filename, sizeof(filename));
-    if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
-        FAIL_STACK_ERROR
-
-    /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
-        TEST_ERROR
-
-    /* Create the dataset */
-    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
-        FAIL_STACK_ERROR
-    if(NULL == HDgetcwd(cwdpath, sizeof(cwdpath)))
-        TEST_ERROR
-    for(i = 0; i < N_EXT_FILES; i++) {
-        HDsnprintf(filename, sizeof(filename), "..%sextern_%dr.raw", H5_DIR_SEPS, (int) i + 1);
-        if(H5Pset_external(dcpl, filename, (off_t)(i * GARBAGE_PER_FILE), (hsize_t)sizeof(part)) < 0)
-            FAIL_STACK_ERROR
-    } /* end for */
-
-    cur_size = TOTAL_SIZE;
-    if((space = H5Screate_simple(1, &cur_size, NULL)) < 0)
-        FAIL_STACK_ERROR
-    if((dapl = H5Pcreate(H5P_DATASET_ACCESS)) < 0)
-        FAIL_STACK_ERROR
-
-    /* Set prefix to a nonexistent directory, will be overwritten by environment variable */
-    if(H5Pset_efile_prefix(dapl, "someprefix") < 0)
-        FAIL_STACK_ERROR
-    if(H5Pget_efile_prefix(dapl, buffer, sizeof(buffer)) < 0)
-        FAIL_STACK_ERROR
-    if(HDstrcmp(buffer, "someprefix") != 0)
-        FAIL_PUTS_ERROR("efile prefix not set correctly");
-
-    /* Create dataset */
-    if((dset = H5Dcreate2(file, "dset1", H5T_NATIVE_INT, space, H5P_DEFAULT, dcpl, dapl)) < 0)
-        FAIL_STACK_ERROR
-
-    /* Read the entire dataset and compare with the original */
-    HDmemset(whole, 0, sizeof(whole));
-    if(H5Dread(dset, H5T_NATIVE_INT, space, space, H5P_DEFAULT, whole) < 0)
-        FAIL_STACK_ERROR
-    for(i = 0; i < TOTAL_SIZE; i++)
-        if(whole[i] != (signed)i)
-            FAIL_PUTS_ERROR("Incorrect value(s) read.");
-
-    if(H5Dclose(dset) < 0) FAIL_STACK_ERROR
-    if(H5Pclose(dapl) < 0) FAIL_STACK_ERROR
-    if(H5Pclose(dcpl) < 0) FAIL_STACK_ERROR
-    if(H5Sclose(space) < 0) FAIL_STACK_ERROR
-    if(H5Fclose(file) < 0) FAIL_STACK_ERROR
-    PASSED();
-    return 0;
-
-error:
-    H5E_BEGIN_TRY {
-        H5Pclose(dapl);
-        H5Dclose(dset);
-        H5Pclose(dcpl);
-        H5Sclose(space);
-        H5Fclose(file);
-    } H5E_END_TRY;
-    return 1;
-} /* end test_path_env() */
-
-
-/*-------------------------------------------------------------------------
  * Function:    test_h5d_get_access_plist
  *
  * Purpose:     Ensure that H5Dget_access_plist returns correct values.
@@ -1437,11 +1210,11 @@ test_h5d_get_access_plist(hid_t fapl_id)
         TEST_ERROR
 
     /* Reset the raw data files */
-    if(reset_raw_data_files() < 0)
+    if(reset_raw_data_files(FALSE) < 0)
         TEST_ERROR
 
     /* Create the file */
-    h5_fixname(FILENAME[5], fapl_id, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[5], fapl_id, filename, sizeof(filename));
     if((fid = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id)) < 0)
         FAIL_STACK_ERROR
 
@@ -1532,7 +1305,7 @@ main(void)
 
     /* Get a fapl for the old (default) file format */
     fapl_id_old = h5_fileaccess();
-    h5_fixname(FILENAME[0], fapl_id_old, filename, sizeof(filename));
+    h5_fixname(EXT_FNAME[0], fapl_id_old, filename, sizeof(filename));
 
     /* Copy and set up a fapl for the latest file format */
     if((fapl_id_new = H5Pcopy(fapl_id_old)) < 0)
@@ -1585,10 +1358,9 @@ main(void)
         nerrors += test_path_absolute(current_fapl_id);
         nerrors += test_path_relative(current_fapl_id);
         nerrors += test_path_relative_cwd(current_fapl_id);
-        nerrors += test_path_env(current_fapl_id);
  
         /* Verify symbol table messages are cached */
-        nerrors += (h5_verify_cached_stabs(FILENAME, current_fapl_id) < 0 ? 1 : 0);
+        nerrors += (h5_verify_cached_stabs(EXT_FNAME, current_fapl_id) < 0 ? 1 : 0);
 
         /* Close the common file */
         if(H5Fclose(fid) < 0) FAIL_STACK_ERROR
@@ -1603,7 +1375,7 @@ main(void)
     HDputs("All external storage tests passed.");
 
     /* Clean up files used by file set tests */
-    if(h5_cleanup(FILENAME, fapl_id_old)) {
+    if(h5_cleanup(EXT_FNAME, fapl_id_old)) {
         HDremove("extern_1r.raw");
         HDremove("extern_2r.raw");
         HDremove("extern_3r.raw");
diff --git a/test/external_common.c b/test/external_common.c
new file mode 100644
index 0000000..c9b6584
--- /dev/null
+++ b/test/external_common.c
@@ -0,0 +1,127 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * 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.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Programmer:  Raymond Lu <songyulu@hdfgroup.org>
+ *              April, 2019
+ *
+ * Purpose:     Private function for external.c and external_env.c
+ */
+
+#include "external_common.h"
+
+
+/*-------------------------------------------------------------------------
+ * Function:    reset_raw_data_files
+ *
+ * Purpose:     Resets the data in the raw data files for tests that
+ *              perform dataset I/O on a set of files.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Dana Robinson
+ *              February 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+reset_raw_data_files(hbool_t is_env)
+{
+    int		    fd = 0;             /* external file descriptor             */
+    size_t	    i, j;               /* iterators                            */
+    hssize_t	n;                  /* bytes of I/O                         */
+    char	    filename[1024];     /* file name                            */
+    int		    data[PART_SIZE];    /* raw data buffer                      */
+    uint8_t     *garbage = NULL;    /* buffer of garbage data               */
+    size_t      garbage_count;      /* size of garbage buffer               */
+    size_t      garbage_bytes;      /* # of garbage bytes written to file   */
+
+    /* Set up garbage buffer */
+    garbage_count = N_EXT_FILES * GARBAGE_PER_FILE;
+    if(NULL == (garbage = (uint8_t *)HDcalloc(garbage_count, sizeof(uint8_t))))
+        goto error;
+    for(i = 0; i < garbage_count; i++)
+        garbage[i] = 0xFF;
+
+    /* The *r files are pre-filled with data and are used to
+     * verify that read operations work correctly.
+     */
+    for(i = 0; i < N_EXT_FILES; i++) {
+
+        /* Open file */
+        if(is_env)
+            HDsprintf(filename, "extern_env_%lur.raw", (unsigned long)i + 1);
+        else
+            HDsprintf(filename, "extern_%lur.raw", (unsigned long)i + 1);
+        if((fd = HDopen(filename, O_RDWR|O_CREAT|O_TRUNC, H5_POSIX_CREATE_MODE_RW)) < 0)
+            goto error;
+        
+        /* Write garbage data to the file. This allows us to test the
+         * the ability to set an offset in the raw data file.
+         */
+        garbage_bytes = i * 10;
+        n = HDwrite(fd, garbage, garbage_bytes);
+        if(n < 0 || (size_t)n != garbage_bytes)
+            goto error;
+
+        /* Fill array with data */
+        for(j = 0; j < PART_SIZE; j++) {
+            data[j] = (int)(i * 25 + j);
+        } /* end for */
+
+        /* Write raw data to the file. */
+        n = HDwrite(fd, data, sizeof(data));
+        if(n != sizeof(data))
+            goto error;
+
+        /* Close this file */
+        HDclose(fd);
+
+    } /* end for */
+
+    /* The *w files are only pre-filled with the garbage data and are
+     * used to verify that write operations work correctly. The individual
+     * tests fill in the actual data.
+     */
+    for(i = 0; i < N_EXT_FILES; i++) {
+
+        /* Open file */
+        if(is_env)
+            HDsprintf(filename, "extern_env_%luw.raw", (unsigned long)i + 1);
+        else
+            HDsprintf(filename, "extern_%luw.raw", (unsigned long)i + 1);
+        if((fd = HDopen(filename, O_RDWR|O_CREAT|O_TRUNC, H5_POSIX_CREATE_MODE_RW)) < 0)
+            goto error;
+        
+        /* Write garbage data to the file. This allows us to test the
+         * the ability to set an offset in the raw data file.
+         */
+        garbage_bytes = i * 10;
+        n = HDwrite(fd, garbage, garbage_bytes);
+        if(n < 0 || (size_t)n != garbage_bytes)
+            goto error;
+
+        /* Close this file */
+        HDclose(fd);
+
+    } /* end for */
+    HDfree(garbage);
+    return SUCCEED;
+
+error:
+    if(fd)
+        HDclose(fd);
+    if(garbage)
+        HDfree(garbage);
+    return FAIL;
+}
diff --git a/test/external_common.h b/test/external_common.h
new file mode 100644
index 0000000..304f3fb
--- /dev/null
+++ b/test/external_common.h
@@ -0,0 +1,46 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * 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.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Programmer:  Raymond Lu <songyulu@hdfgroup.org>
+ *              April, 2019
+ *
+ * Purpose:     Private function for external.c and external_env.c
+ */
+#ifndef _EXTERNAL_COMMON_H
+#define _EXTERNAL_COMMON_H
+
+/* Include test header files */
+#include "h5test.h"
+
+static const char *EXT_FNAME[] = {
+    "extern_1",
+    "extern_2",
+    "extern_3",
+    "extern_4",
+    "extern_dir/file_1",
+    "extern_5",
+    "extern_env_dir/file_2",
+    NULL
+};
+
+/* A similar collection of files is used for the tests that
+ * perform file I/O.
+ */
+#define N_EXT_FILES         4
+#define PART_SIZE           25
+#define TOTAL_SIZE          100
+#define GARBAGE_PER_FILE    10
+
+herr_t reset_raw_data_files(hbool_t is_env);
+#endif /* _EXTERNAL_COMMON_H */
diff --git a/test/external_env.c b/test/external_env.c
new file mode 100644
index 0000000..284a2f0
--- /dev/null
+++ b/test/external_env.c
@@ -0,0 +1,212 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * 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:	Tests datasets stored in external raw files.
+ */
+#include "external_common.h"
+
+
+/*-------------------------------------------------------------------------
+ * Function:    test_path_env
+ *
+ * Purpose:     Test whether the value of HDF5_EXTFILE_PREFIX will overwrite
+ *              the efile_prefix dataset access property.
+ *              This will create an HDF5 file in a subdirectory which will
+ *              refer to ../extern_*a.raw
+ *              The files are then accessed by setting the HDF5_EXTFILE_PREFIX
+ *              environment variable to "${ORIGIN}".
+ *              The efile_prefix dataset access property is set to "someprefix",
+ *              which will cause an error if the value is not overwritten by
+ *              the environment variable.
+ *
+ * Return:      Success:    0
+ *              Failure:    1
+ *
+ * Programmer:  Steffen Kiess
+ *              March 10, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+test_path_env(hid_t fapl)
+{
+    hid_t	file = -1;          /* file to write to                     */
+    hid_t	dcpl = -1;          /* dataset creation properties          */
+    hid_t	space = -1;         /* data space                           */
+    hid_t	dapl = -1;          /* dataset access property list         */
+    hid_t	dset = -1;          /* dataset                              */
+    size_t	i;                  /* miscellaneous counters               */
+    char	cwdpath[1024];		/* working directory                    */
+    char	filename[1024];		/* file name                            */
+    int	    part[PART_SIZE];    /* raw data buffer (partial)            */
+    int     whole[TOTAL_SIZE];  /* raw data buffer (total)              */
+    hsize_t	cur_size;           /* current data space size              */
+    char	buffer[1024];       /* buffer to read efile_prefix          */
+
+    TESTING("prefix in HDF5_EXTFILE_PREFIX");
+
+    if(HDmkdir("extern_env_dir", (mode_t)0755) < 0 && errno != EEXIST)
+        TEST_ERROR;
+
+    h5_fixname(EXT_FNAME[6], fapl, filename, sizeof(filename));
+    if((file = H5Fcreate(filename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Reset the raw data files */
+    if(reset_raw_data_files(TRUE) < 0)
+        TEST_ERROR
+
+    /* Create the dataset */
+    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
+        FAIL_STACK_ERROR
+    if(NULL == HDgetcwd(cwdpath, sizeof(cwdpath)))
+        TEST_ERROR
+    for(i = 0; i < N_EXT_FILES; i++) {
+        HDsnprintf(filename, sizeof(filename), "..%sextern_env_%dr.raw", H5_DIR_SEPS, (int) i + 1);
+        if(H5Pset_external(dcpl, filename, (off_t)(i * GARBAGE_PER_FILE), (hsize_t)sizeof(part)) < 0)
+            FAIL_STACK_ERROR
+    } /* end for */
+
+    cur_size = TOTAL_SIZE;
+    if((space = H5Screate_simple(1, &cur_size, NULL)) < 0)
+        FAIL_STACK_ERROR
+    if((dapl = H5Pcreate(H5P_DATASET_ACCESS)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set prefix to a nonexistent directory, will be overwritten by environment variable */
+    if(H5Pset_efile_prefix(dapl, "someprefix") < 0)
+        FAIL_STACK_ERROR
+    if(H5Pget_efile_prefix(dapl, buffer, sizeof(buffer)) < 0)
+        FAIL_STACK_ERROR
+    if(HDstrcmp(buffer, "someprefix") != 0)
+        FAIL_PUTS_ERROR("efile prefix not set correctly");
+
+    /* Create dataset */
+    if((dset = H5Dcreate2(file, "dset1", H5T_NATIVE_INT, space, H5P_DEFAULT, dcpl, dapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Read the entire dataset and compare with the original */
+    HDmemset(whole, 0, sizeof(whole));
+    if(H5Dread(dset, H5T_NATIVE_INT, space, space, H5P_DEFAULT, whole) < 0)
+        FAIL_STACK_ERROR
+    for(i = 0; i < TOTAL_SIZE; i++)
+        if(whole[i] != (signed)i)
+            FAIL_PUTS_ERROR("Incorrect value(s) read.");
+
+    if(H5Dclose(dset) < 0) FAIL_STACK_ERROR
+    if(H5Pclose(dapl) < 0) FAIL_STACK_ERROR
+    if(H5Pclose(dcpl) < 0) FAIL_STACK_ERROR
+    if(H5Sclose(space) < 0) FAIL_STACK_ERROR
+    if(H5Fclose(file) < 0) FAIL_STACK_ERROR
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY {
+        H5Pclose(dapl);
+        H5Dclose(dset);
+        H5Pclose(dcpl);
+        H5Sclose(space);
+        H5Fclose(file);
+    } H5E_END_TRY;
+    return 1;
+} /* end test_path_env() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    main
+ *
+ * Purpose:     Runs external dataset tests.
+ *
+ * Return:      EXIT_SUCCESS/EXIT_FAILURE
+ *
+ * Programmer:	Robb Matzke
+ *              Tuesday, March  3, 1998
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+main(void)
+{
+    hid_t	fapl_id_old = -1;   /* file access properties (old format)  */
+    hid_t	fapl_id_new = -1;   /* file access properties (new format)  */
+    hid_t	fid = -1;           /* file for test_1* functions           */
+    hid_t	gid = -1;           /* group to emit diagnostics            */
+    unsigned latest_format;     /* default or latest file format        */
+    int		nerrors = 0;        /* number of errors                     */
+
+    h5_reset();
+
+    /* Get a fapl for the old (default) file format */
+    fapl_id_old = h5_fileaccess();
+
+    /* Copy and set up a fapl for the latest file format */
+    if((fapl_id_new = H5Pcopy(fapl_id_old)) < 0)
+        FAIL_STACK_ERROR
+    if(H5Pset_libver_bounds(fapl_id_new, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0)
+        FAIL_STACK_ERROR
+
+    /* Test with old & new format groups */
+    for(latest_format = FALSE; latest_format <= TRUE; latest_format++) {
+        hid_t current_fapl_id = -1;
+
+        /* Set the fapl for different file formats */
+        if(latest_format) {
+            HDputs("\nTesting with the latest file format:");
+            current_fapl_id = fapl_id_new;
+        } /* end if */
+        else {
+            HDputs("Testing with the default file format:");
+            current_fapl_id = fapl_id_old;
+        } /* end else */
+
+        nerrors += test_path_env(current_fapl_id);
+    } /* end for */
+
+    if(nerrors > 0) goto error;
+
+    /* Close the new ff fapl. h5_cleanup will take care of the old ff fapl */
+    if(H5Pclose(fapl_id_new) < 0) FAIL_STACK_ERROR
+
+    HDputs("All external storage tests passed.");
+
+    /* Clean up files used by file set tests */
+    if(h5_cleanup(EXT_FNAME, fapl_id_old)) {
+        HDremove("extern_env_1r.raw");
+        HDremove("extern_env_2r.raw");
+        HDremove("extern_env_3r.raw");
+        HDremove("extern_env_4r.raw");
+
+        HDremove("extern_env_1w.raw");
+        HDremove("extern_env_2w.raw");
+        HDremove("extern_env_3w.raw");
+        HDremove("extern_env_4w.raw");
+
+        HDrmdir("extern_dir");
+    } /* end if */
+
+    return EXIT_SUCCESS;
+
+error:
+    H5E_BEGIN_TRY {
+        H5Fclose(fid);
+        H5Pclose(fapl_id_old);
+        H5Pclose(fapl_id_new);
+        H5Gclose(gid);
+    } H5E_END_TRY;
+    nerrors = MAX(1, nerrors);
+    printf("%d TEST%s FAILED.\n", nerrors, 1 == nerrors ? "" : "s");
+    return EXIT_FAILURE;
+} /* end main() */
diff --git a/test/testexternal_env.sh.in b/test/testexternal_env.sh.in
new file mode 100644
index 0000000..cfd0825
--- /dev/null
+++ b/test/testexternal_env.sh.in
@@ -0,0 +1,39 @@
+# Copyright by the Board of Trustees of the University of Illinois.
+# 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.
+#
+# Test for external file with environment variable: HDF5_EXTFILE_PREFIX
+
+srcdir=@srcdir@
+
+nerrors=0
+
+##############################################################################
+##############################################################################
+###			  T H E   T E S T S                                ###
+##############################################################################
+##############################################################################
+
+# test for external file with HDF5_EXTFILE_PREFIX
+echo "Testing external file with HDF5_EXTFILE_PREFIX"
+TEST_NAME=external_env                         # The test name
+TEST_BIN=`pwd`/$TEST_NAME                      # The path of the test binary
+ENVCMD="env HDF5_EXTFILE_PREFIX=\${ORIGIN}"    # The environment variable & value
+#
+# Run the test
+# echo "$ENVCMD $RUNSERIAL $TEST_BIN"
+$ENVCMD $RUNSERIAL $TEST_BIN
+exitcode=$?
+if [ $exitcode -eq 0 ]; then
+        echo "Test prefix for HDF5_EXTFILE_PREFIX PASSED"
+    else
+ 	nerrors="`expr $nerrors + 1`"
+	echo "***Error encountered for HDF5_EXTFILE_PREFIX test***"
+fi
+exit $nerrors
diff --git a/test/testvds_env.sh.in b/test/testvds_env.sh.in
new file mode 100644
index 0000000..894e52e
--- /dev/null
+++ b/test/testvds_env.sh.in
@@ -0,0 +1,44 @@
+#! /bin/sh
+#
+# Copyright by The HDF Group.
+# Copyright by the Board of Trustees of the University of Illinois.
+# All rights reserved.
+#
+# This file is part of HDF5.  The full HDF5 copyright notice, including
+# terms governing use, modification, and redistribution, is contained in
+# the COPYING file, which can be found at the root of the source code
+# distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.
+# If you do not have access to either file, you may request a copy from
+# help@hdfgroup.org.
+#
+# Test for external file with environment variable: HDF5_VDS_PREFIX
+
+srcdir=@srcdir@
+
+nerrors=0
+
+##############################################################################
+##############################################################################
+###			  T H E   T E S T S                                ###
+##############################################################################
+##############################################################################
+
+# test for VDS with HDF5_VDS_PREFIX
+echo "Testing basic virtual dataset I/O via H5Pset_vds_prefix(): all selection with ENV prefix"
+TEST_NAME=vds_env                               # The test name
+TEST_BIN=`pwd`/$TEST_NAME                       # The path of the test binary
+ENVCMD="env HDF5_VDS_PREFIX=\${ORIGIN}/tmp"     # Set the environment variable & value
+UNENVCMD="unset HDF5_VDS_PREFIX"                # Unset the environment variable & value
+#
+# Run the test
+# echo "$ENVCMD $RUNSERIAL $TEST_BIN"
+$ENVCMD $RUNSERIAL $TEST_BIN
+exitcode=$?
+if [ $exitcode -eq 0 ]; then
+        echo "Test prefix for HDF5_VDS_PREFIX PASSED"
+    else
+ 	nerrors="`expr $nerrors + 1`"
+	echo "***Error encountered for HDF5_VDS_PREFIX test***"
+fi
+$UNENVCMD
+exit $nerrors
diff --git a/test/vds.c b/test/vds.c
index e4f886e..fd5a431 100644
--- a/test/vds.c
+++ b/test/vds.c
@@ -1121,7 +1121,7 @@ error:
 } /* end test_api() */
 
 /*-------------------------------------------------------------------------
- * Function:    vds_link_prefix
+ * Function:    vds_link_prefix_first
  *
  * Purpose:     Set up vds link prefix via H5Pset_virtual_prefix() to be "tmp"
  *        Should be able to access the target source files in tmp directory via the prefix set
@@ -1132,7 +1132,7 @@ error:
  *-------------------------------------------------------------------------
  */
 static int
-test_vds_prefix(unsigned config, hid_t fapl)
+test_vds_prefix_first(unsigned config, hid_t fapl)
 {
     char        srcfilename[FILENAME_BUF_SIZE];
     char        srcfilename_map[FILENAME_BUF_SIZE];
@@ -1158,7 +1158,7 @@ test_vds_prefix(unsigned config, hid_t fapl)
     int         i, j;
     char        buffer[1024];   /* buffer to read vds_prefix       */
 
-    TESTING("basic virtual dataset I/O via H5Pset_vds_prefix()")
+    TESTING("basic virtual dataset I/O via H5Pset_vds_prefix(): all selection")
 
     h5_fixname(FILENAME[0], fapl, vfilename, sizeof vfilename);
     h5_fixname(FILENAME[7], fapl, vfilename2, sizeof vfilename2);
@@ -1191,9 +1191,6 @@ test_vds_prefix(unsigned config, hid_t fapl)
     if(HDstrcmp(buffer, TMPDIR) != 0)
         FAIL_PUTS_ERROR("vds prefix not set correctly");
 
-    /*
-     * Test 1: All - all selection
-     */
     /* Create source dataspace */
     if((srcspace[0] = H5Screate_simple(2, dims, NULL)) < 0)
         TEST_ERROR
@@ -1346,187 +1343,6 @@ test_vds_prefix(unsigned config, hid_t fapl)
         TEST_ERROR
     dcpl = -1;
 
-    /*
-     * Test 2: All - all selection with ENV prefix
-     */
-    if(HDsetenv("HDF5_VDS_PREFIX", "${ORIGIN}/tmp", 1))
-        TEST_ERROR
-
-    /* Create DCPL */
-    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
-        TEST_ERROR
-
-    /* Set fill value */
-    if(H5Pset_fill_value(dcpl, H5T_NATIVE_INT, &fill) < 0)
-        TEST_ERROR
-
-    /* Set prefix to a nonexistent directory, will be overwritten by environment variable */
-    if((dapl = H5Pcreate(H5P_DATASET_ACCESS)) < 0)
-        TEST_ERROR
-
-    if(H5Pset_virtual_prefix(dapl, "someprefix") < 0)
-        TEST_ERROR
-    if(H5Pget_virtual_prefix(dapl, buffer, sizeof(buffer)) < 0)
-        TEST_ERROR
-
-    if(HDstrcmp(buffer, "someprefix") != 0)
-        FAIL_PUTS_ERROR("vds prefix not set correctly");
-
-    /* Create source dataspace */
-    if((srcspace[0] = H5Screate_simple(2, dims, NULL)) < 0)
-        TEST_ERROR
-
-    /* Create virtual dataspace */
-    if((vspace[0] = H5Screate_simple(2, dims, NULL)) < 0)
-        TEST_ERROR
-
-    /* Select all (should not be necessary, but just to be sure) */
-    if(H5Sselect_all(srcspace[0]) < 0)
-        TEST_ERROR
-    if(H5Sselect_all(vspace[0]) < 0)
-        TEST_ERROR
-
-    /* Add virtual layout mapping */
-    if(H5Pset_virtual(dcpl, vspace[0], config & TEST_IO_DIFFERENT_FILE ? srcfilename_map : ".", "src_dset", srcspace[0]) < 0)
-        TEST_ERROR
-
-    /* Create virtual file */
-    if((vfile = H5Fcreate(vfilename2, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
-        TEST_ERROR
-
-    /* Create source file if requested */
-    if(config & TEST_IO_DIFFERENT_FILE) {
-        HDgetcwd(buffer, 1024);
-        HDchdir(TMPDIR);
-        if((srcfile[0] = H5Fcreate(srcfilename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
-            TEST_ERROR
-        HDchdir(buffer);
-    }
-    else {
-        srcfile[0] = vfile;
-        if(H5Iinc_ref(srcfile[0]) < 0)
-            TEST_ERROR
-    }
-
-    /* Create source dataset */
-    if((srcdset[0] = H5Dcreate2(srcfile[0], "src_dset", H5T_NATIVE_INT, srcspace[0], H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
-        TEST_ERROR
-
-    /* Create virtual dataset */
-    if((vdset = H5Dcreate2(vfile, "v_dset", H5T_NATIVE_INT, vspace[0], H5P_DEFAULT, dcpl, dapl)) < 0)
-        TEST_ERROR
-
-    /* Populate write buffer */
-    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
-        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
-            buf[i][j] = (i * (int)(sizeof(buf[0]) / sizeof(buf[0][0]))) + j;
-
-    /* Write data directly to source dataset */
-    if(H5Dwrite(srcdset[0], H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf[0]) < 0)
-        TEST_ERROR
-
-    /* Close srcdset and srcfile if config option specified */
-    if(config & TEST_IO_CLOSE_SRC) {
-        if(H5Dclose(srcdset[0]) < 0)
-            TEST_ERROR
-        srcdset[0] = -1;
-
-        if(config & TEST_IO_DIFFERENT_FILE) {
-            if(H5Fclose(srcfile[0]) < 0)
-                TEST_ERROR
-            srcfile[0] = -1;
-        }
-    }
-
-    /* Reopen virtual dataset and file if config option specified */
-    if(config & TEST_IO_REOPEN_VIRT) {
-        if(H5Dclose(vdset) < 0)
-            TEST_ERROR
-        vdset = -1;
-        if(H5Fclose(vfile) < 0)
-            TEST_ERROR
-        vfile = -1;
-        if((vfile = H5Fopen(vfilename2, H5F_ACC_RDWR, fapl)) < 0)
-            TEST_ERROR
-        if((vdset = H5Dopen2(vfile, "v_dset", dapl)) < 0)
-            TEST_ERROR
-    }
-
-    /* Read data through virtual dataset */
-    HDmemset(rbuf[0], 0, sizeof(rbuf));
-    if(H5Dread(vdset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf[0]) < 0)
-        TEST_ERROR
-
-    /* Verify read data */
-    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++) {
-        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
-            if(rbuf[i][j] != buf[i][j]) {
-                TEST_ERROR
-            }
-    }
-
-    /* Adjust write buffer */
-    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
-        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
-            buf[i][j] += (int)(sizeof(buf) / sizeof(buf[0][0]));
-
-    /* Write data through virtual dataset */
-    if(H5Dwrite(vdset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf[0]) < 0)
-        TEST_ERROR
-
-    /* Reopen srcdset and srcfile if config option specified */
-    if(config & TEST_IO_CLOSE_SRC) {
-        if(config & TEST_IO_DIFFERENT_FILE) {
-            HDgetcwd(buffer, 1024);
-            HDchdir(TMPDIR);
-            if((srcfile[0] = H5Fopen(srcfilename, H5F_ACC_RDONLY, fapl)) < 0)
-                TEST_ERROR
-            HDchdir(buffer);
-        }
-        if((srcdset[0] = H5Dopen2(srcfile[0], "src_dset", H5P_DEFAULT)) < 0)
-            TEST_ERROR
-    }
-
-    /* Read data directly from source dataset */
-    HDmemset(rbuf[0], 0, sizeof(rbuf));
-    if(H5Dread(srcdset[0], H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf[0]) < 0)
-        TEST_ERROR
-
-    /* Verify read data */
-    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
-        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
-            if(rbuf[i][j] != buf[i][j])
-                TEST_ERROR
-
-    /* Close */
-    if(H5Dclose(vdset) < 0)
-        TEST_ERROR
-    vdset = -1;
-    if(H5Dclose(srcdset[0]) < 0)
-        TEST_ERROR
-    srcdset[0] = -1;
-    if(H5Fclose(srcfile[0]) < 0)
-        TEST_ERROR
-    srcfile[0] = -1;
-    if(H5Fclose(vfile) < 0)
-        TEST_ERROR
-    vfile = -1;
-    if(H5Sclose(srcspace[0]) < 0)
-        TEST_ERROR
-    srcspace[0] = -1;
-    if(H5Sclose(vspace[0]) < 0)
-        TEST_ERROR
-    vspace[0] = -1;
-    if(H5Pclose(dapl) < 0)
-        TEST_ERROR
-    dapl = -1;
-    if(H5Pclose(dcpl) < 0)
-        TEST_ERROR
-    dcpl = -1;
-
-    if(HDsetenv("HDF5_VDS_PREFIX", "", 1) < 0)
-        TEST_ERROR
-
     PASSED();
     return 0;
 
@@ -1538,7 +1354,6 @@ test_vds_prefix(unsigned config, hid_t fapl)
         for(i = 0; i < (int)(sizeof(srcfile) / sizeof(srcfile[0])); i++)
             H5Fclose(srcfile[i]);
         H5Fclose(vfile);
-        H5Fclose(vfile2);
         for(i = 0; i < (int)(sizeof(srcspace) / sizeof(srcspace[0])); i++)
             H5Sclose(srcspace[i]);
         for(i = 0; i < (int)(sizeof(vspace) / sizeof(vspace[0])); i++)
@@ -1552,7 +1367,7 @@ test_vds_prefix(unsigned config, hid_t fapl)
         TEST_ERROR
 
     return 1;
-} /* end vds_link_prefix() */
+} /* end test_vds_prefix() */
 
 
 /*-------------------------------------------------------------------------
@@ -11623,7 +11438,7 @@ main(void)
     for(bit_config = 0; bit_config < TEST_IO_NTESTS; bit_config++) {
         printf("Config: %s%s%s\n", bit_config & TEST_IO_CLOSE_SRC ? "closed source dataset, " : "", bit_config & TEST_IO_DIFFERENT_FILE ? "different source file" : "same source file", bit_config & TEST_IO_REOPEN_VIRT ? ", reopen virtual file" : "");
         nerrors += test_basic_io(bit_config, fapl);
-        nerrors += test_vds_prefix(bit_config, fapl);
+        nerrors += test_vds_prefix_first(bit_config, fapl);
         nerrors += test_unlim(bit_config, fapl);
         nerrors += test_printf(bit_config, fapl);
         nerrors += test_all(bit_config, fapl);
diff --git a/test/vds_env.c b/test/vds_env.c
new file mode 100644
index 0000000..1c2dba9
--- /dev/null
+++ b/test/vds_env.c
@@ -0,0 +1,327 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Programmer:  Neil Fortner <nfortne2@hdfgroup.org>
+ *              Monday, February 16, 2015
+ *
+ * Purpose:     Tests datasets with virtual layout.
+ */
+#include "h5test.h"
+
+const char *FILENAME[] = {
+    "vds_env_virt_0",
+    "vds_env_virt_3",
+    "vds_env_src_2",
+    "vds_env_%%_src2",
+    NULL
+};
+
+/* I/O test config flags */
+#define TEST_IO_CLOSE_SRC       0x01u
+#define TEST_IO_DIFFERENT_FILE  0x02u
+#define TEST_IO_REOPEN_VIRT     0x04u
+#define TEST_IO_NTESTS          0x08u
+
+#define FILENAME_BUF_SIZE       1024
+
+#define TMPDIR          "tmp/"
+
+/*-------------------------------------------------------------------------
+ * Function:    test_vds_prefix_second
+ *
+ * Purpose:     Set up vds link prefix via H5Pset_virtual_prefix() to be "tmp"
+ *        Should be able to access the target source files in tmp directory via the prefix set
+ *        by H5Pset_virtual_prefix()
+ *
+ * Return:      Success:        0
+ *              Failure:        -1
+ *-------------------------------------------------------------------------
+ */
+static int
+test_vds_prefix_second(unsigned config, hid_t fapl)
+{
+    char        srcfilename[FILENAME_BUF_SIZE];
+    char        srcfilename_map[FILENAME_BUF_SIZE];
+    char        vfilename[FILENAME_BUF_SIZE];
+    char        vfilename2[FILENAME_BUF_SIZE];
+    char        srcfilenamepct[FILENAME_BUF_SIZE];
+    char        srcfilenamepct_map[FILENAME_BUF_SIZE];
+    const char *srcfilenamepct_map_orig = "vds%%%%_src";
+    hid_t       srcfile[4] = {-1, -1, -1, -1}; /* Files with source dsets */
+    hid_t       vfile = -1;     /* File with virtual dset */
+    hid_t       dcpl = -1;      /* Dataset creation property list */
+    hid_t       dapl = -1;      /* Dataset access property list */
+    hid_t       srcspace[4] = {-1, -1, -1, -1}; /* Source dataspaces */
+    hid_t       vspace[4] = {-1, -1, -1, -1}; /* Virtual dset dataspaces */
+    hid_t       memspace = -1;  /* Memory dataspace */
+    hid_t       srcdset[4] = {-1, -1, -1, -1}; /* Source datsets */
+    hid_t       vdset = -1;     /* Virtual dataset */
+    hsize_t     dims[4] = {10, 26, 0, 0}; /* Data space current size */
+    int         buf[10][26];    /* Write and expected read buffer */
+    int         rbuf[10][26];   /* Read buffer */
+    int         fill = -1;      /* Fill value */
+    int         i, j;
+    char        buffer[1024];   /* buffer to read vds_prefix       */
+
+    TESTING("basic virtual dataset I/O via H5Pset_vds_prefix(): all selection with ENV prefix")
+
+    h5_fixname(FILENAME[0], fapl, vfilename, sizeof vfilename);
+    h5_fixname(FILENAME[1], fapl, vfilename2, sizeof vfilename2);
+    h5_fixname(FILENAME[2], fapl, srcfilename, sizeof srcfilename);
+    h5_fixname_printf(FILENAME[2], fapl, srcfilename_map, sizeof srcfilename_map);
+    h5_fixname(FILENAME[3], fapl, srcfilenamepct, sizeof srcfilenamepct);
+    h5_fixname_printf(srcfilenamepct_map_orig, fapl, srcfilenamepct_map, sizeof srcfilenamepct_map);
+
+    /* create tmp directory and get current working directory path */
+    if (HDmkdir(TMPDIR, (mode_t)0755) < 0 && errno != EEXIST)
+        TEST_ERROR
+
+    /* Create DCPL */
+    if((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
+        TEST_ERROR
+
+    /* Set fill value */
+    if(H5Pset_fill_value(dcpl, H5T_NATIVE_INT, &fill) < 0)
+        TEST_ERROR
+
+    /* Set prefix to a nonexistent directory, will be overwritten by environment variable */
+    if((dapl = H5Pcreate(H5P_DATASET_ACCESS)) < 0)
+        TEST_ERROR
+
+    if(H5Pset_virtual_prefix(dapl, "someprefix") < 0)
+        TEST_ERROR
+    if(H5Pget_virtual_prefix(dapl, buffer, sizeof(buffer)) < 0)
+        TEST_ERROR
+
+    if(HDstrcmp(buffer, "someprefix") != 0)
+        FAIL_PUTS_ERROR("vds prefix not set correctly");
+
+    /* Create source dataspace */
+    if((srcspace[0] = H5Screate_simple(2, dims, NULL)) < 0)
+        TEST_ERROR
+
+    /* Create virtual dataspace */
+    if((vspace[0] = H5Screate_simple(2, dims, NULL)) < 0)
+        TEST_ERROR
+
+    /* Select all (should not be necessary, but just to be sure) */
+    if(H5Sselect_all(srcspace[0]) < 0)
+        TEST_ERROR
+    if(H5Sselect_all(vspace[0]) < 0)
+        TEST_ERROR
+
+    /* Add virtual layout mapping */
+    if(H5Pset_virtual(dcpl, vspace[0], config & TEST_IO_DIFFERENT_FILE ? srcfilename_map : ".", "src_dset", srcspace[0]) < 0)
+        TEST_ERROR
+
+    /* Create virtual file */
+    if((vfile = H5Fcreate(vfilename2, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
+        TEST_ERROR
+
+    /* Create source file if requested */
+    if(config & TEST_IO_DIFFERENT_FILE) {
+        HDgetcwd(buffer, 1024);
+        HDchdir(TMPDIR);
+        if((srcfile[0] = H5Fcreate(srcfilename, H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0)
+            TEST_ERROR
+        HDchdir(buffer);
+    }
+    else {
+        srcfile[0] = vfile;
+        if(H5Iinc_ref(srcfile[0]) < 0)
+            TEST_ERROR
+    }
+
+    /* Create source dataset */
+    if((srcdset[0] = H5Dcreate2(srcfile[0], "src_dset", H5T_NATIVE_INT, srcspace[0], H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
+        TEST_ERROR
+
+    /* Create virtual dataset */
+    if((vdset = H5Dcreate2(vfile, "v_dset", H5T_NATIVE_INT, vspace[0], H5P_DEFAULT, dcpl, dapl)) < 0)
+        TEST_ERROR
+
+    /* Populate write buffer */
+    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
+        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
+            buf[i][j] = (i * (int)(sizeof(buf[0]) / sizeof(buf[0][0]))) + j;
+
+    /* Write data directly to source dataset */
+    if(H5Dwrite(srcdset[0], H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf[0]) < 0)
+        TEST_ERROR
+
+    /* Close srcdset and srcfile if config option specified */
+    if(config & TEST_IO_CLOSE_SRC) {
+        if(H5Dclose(srcdset[0]) < 0)
+            TEST_ERROR
+        srcdset[0] = -1;
+
+        if(config & TEST_IO_DIFFERENT_FILE) {
+            if(H5Fclose(srcfile[0]) < 0)
+                TEST_ERROR
+            srcfile[0] = -1;
+        }
+    }
+
+    /* Reopen virtual dataset and file if config option specified */
+    if(config & TEST_IO_REOPEN_VIRT) {
+        if(H5Dclose(vdset) < 0)
+            TEST_ERROR
+        vdset = -1;
+        if(H5Fclose(vfile) < 0)
+            TEST_ERROR
+        vfile = -1;
+        if((vfile = H5Fopen(vfilename2, H5F_ACC_RDWR, fapl)) < 0)
+            TEST_ERROR
+        if((vdset = H5Dopen2(vfile, "v_dset", dapl)) < 0)
+            TEST_ERROR
+    }
+
+    /* Read data through virtual dataset */
+    HDmemset(rbuf[0], 0, sizeof(rbuf));
+    if(H5Dread(vdset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf[0]) < 0)
+        TEST_ERROR
+
+    /* Verify read data */
+    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++) {
+        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
+            if(rbuf[i][j] != buf[i][j]) {
+                TEST_ERROR
+            }
+    }
+
+    /* Adjust write buffer */
+    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
+        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
+            buf[i][j] += (int)(sizeof(buf) / sizeof(buf[0][0]));
+
+    /* Write data through virtual dataset */
+    if(H5Dwrite(vdset, H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf[0]) < 0)
+        TEST_ERROR
+
+    /* Reopen srcdset and srcfile if config option specified */
+    if(config & TEST_IO_CLOSE_SRC) {
+        if(config & TEST_IO_DIFFERENT_FILE) {
+            HDgetcwd(buffer, 1024);
+            HDchdir(TMPDIR);
+            if((srcfile[0] = H5Fopen(srcfilename, H5F_ACC_RDONLY, fapl)) < 0)
+                TEST_ERROR
+            HDchdir(buffer);
+        }
+        if((srcdset[0] = H5Dopen2(srcfile[0], "src_dset", H5P_DEFAULT)) < 0)
+            TEST_ERROR
+    }
+
+    /* Read data directly from source dataset */
+    HDmemset(rbuf[0], 0, sizeof(rbuf));
+    if(H5Dread(srcdset[0], H5T_NATIVE_INT, H5S_ALL, H5S_ALL, H5P_DEFAULT, rbuf[0]) < 0)
+        TEST_ERROR
+
+    /* Verify read data */
+    for(i = 0; i < (int)(sizeof(buf) / sizeof(buf[0])); i++)
+        for(j = 0; j < (int)(sizeof(buf[0]) / sizeof(buf[0][0])); j++)
+            if(rbuf[i][j] != buf[i][j])
+                TEST_ERROR
+
+    /* Close */
+    if(H5Dclose(vdset) < 0)
+        TEST_ERROR
+    vdset = -1;
+    if(H5Dclose(srcdset[0]) < 0)
+        TEST_ERROR
+    srcdset[0] = -1;
+    if(H5Fclose(srcfile[0]) < 0)
+        TEST_ERROR
+    srcfile[0] = -1;
+    if(H5Fclose(vfile) < 0)
+        TEST_ERROR
+    vfile = -1;
+    if(H5Sclose(srcspace[0]) < 0)
+        TEST_ERROR
+    srcspace[0] = -1;
+    if(H5Sclose(vspace[0]) < 0)
+        TEST_ERROR
+    vspace[0] = -1;
+    if(H5Pclose(dapl) < 0)
+        TEST_ERROR
+    dapl = -1;
+    if(H5Pclose(dcpl) < 0)
+        TEST_ERROR
+    dcpl = -1;
+
+    PASSED();
+    return 0;
+
+ error:
+    H5E_BEGIN_TRY {
+        for(i = 0; i < (int)(sizeof(srcdset) / sizeof(srcdset[0])); i++)
+            H5Dclose(srcdset[i]);
+        H5Dclose(vdset);
+        for(i = 0; i < (int)(sizeof(srcfile) / sizeof(srcfile[0])); i++)
+            H5Fclose(srcfile[i]);
+        H5Fclose(vfile);
+        for(i = 0; i < (int)(sizeof(srcspace) / sizeof(srcspace[0])); i++)
+            H5Sclose(srcspace[i]);
+        for(i = 0; i < (int)(sizeof(vspace) / sizeof(vspace[0])); i++)
+            H5Sclose(vspace[i]);
+        H5Sclose(memspace);
+        H5Pclose(dapl);
+        H5Pclose(dcpl);
+    } H5E_END_TRY;
+
+    return 1;
+} /* end test_vds_prefix2 */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    main
+ *
+ * Purpose:     Tests datasets with virtual layout
+ *
+ * Return:      EXIT_SUCCESS/EXIT_FAILURE
+ *-------------------------------------------------------------------------
+ */
+int
+main(void)
+{
+    hid_t fapl;
+    int test_api_config;
+    unsigned bit_config;
+    H5F_libver_t low, high;     /* Low and high bounds */
+    unsigned latest = FALSE;    /* Using the latest library version bound */
+    int nerrors = 0;
+
+    /* Testing setup */
+    h5_reset();
+    fapl = h5_fileaccess();
+
+    for(bit_config = 0; bit_config < TEST_IO_NTESTS; bit_config++) {
+	HDprintf("Config: %s%s%s\n", bit_config & TEST_IO_CLOSE_SRC ? "closed source dataset, " : "", bit_config & TEST_IO_DIFFERENT_FILE ? "different source file" : "same source file", bit_config & TEST_IO_REOPEN_VIRT ? ", reopen virtual file" : "");
+	nerrors += test_vds_prefix_second(bit_config, fapl);
+    }
+
+    /* Verify symbol table messages are cached */
+    nerrors += (h5_verify_cached_stabs(FILENAME, fapl) < 0 ? 1 : 0);
+
+    if(nerrors)
+        goto error;
+    HDprintf("All virtual dataset tests passed.\n");
+    h5_cleanup(FILENAME, fapl);
+
+    return EXIT_SUCCESS;
+
+error:
+    nerrors = MAX(1, nerrors);
+    HDprintf("***** %d VIRTUAL DATASET TEST%s FAILED! *****\n",
+            nerrors, 1 == nerrors ? "" : "S");
+    return EXIT_FAILURE;
+} /* end main() */