Specify the default VOL connector to use with an environment variable.

This implicitly adds support for changing the VOL connector for command-line
tools or any application linked with the library.

Also, add 'make check-vol' support for all directories, clearing up necessary
issues in testing scripts, etc.

13 files changed, 840 insertions, 286 deletions

diff --git a/src/H5.c b/src/H5.c
index bf4643c..104c9fd 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -214,7 +214,7 @@ H5_init_library(void)
      */
     if(H5E_init() < 0)
         HGOTO_ERROR(H5E_FUNC, H5E_CANTINIT, FAIL, "unable to initialize error interface")
-    if(H5VL_init() < 0)
+    if(H5VL_init_phase1() < 0)
         HGOTO_ERROR(H5E_FUNC, H5E_CANTINIT, FAIL, "unable to initialize vol interface")
     if(H5P_init() < 0)
         HGOTO_ERROR(H5E_FUNC, H5E_CANTINIT, FAIL, "unable to initialize property list interface")
@@ -229,6 +229,10 @@ H5_init_library(void)
     if(H5FS_init() < 0)
         HGOTO_ERROR(H5E_FUNC, H5E_CANTINIT, FAIL, "unable to initialize FS interface")
 
+    /* Finish initializing interfaces that depend on the interfaces above */
+    if(H5VL_init_phase2() < 0)
+        HGOTO_ERROR(H5E_FUNC, H5E_CANTINIT, FAIL, "unable to initialize vol interface")
+
     /* Debugging? */
     H5_debug_mask("-all");
     H5_debug_mask(HDgetenv("HDF5_DEBUG"));
diff --git a/src/H5Dcontig.c b/src/H5Dcontig.c
index ad12ba0..8bd5e31 100644
--- a/src/H5Dcontig.c
+++ b/src/H5Dcontig.c
@@ -755,11 +755,6 @@ H5D__contig_readvv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
 
             /* Reset sieve buffer dirty flag */
             dset_contig->sieve_dirty = FALSE;
-
-            /* Stash local copies of these value */
-            sieve_start = dset_contig->sieve_loc;
-            sieve_size = dset_contig->sieve_size;
-            sieve_end = sieve_start+sieve_size;
         } /* end else */
     } /* end if */
     else {
@@ -825,11 +820,6 @@ H5D__contig_readvv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
                 min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size); 
                 H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);
 
-                /* Update local copies of sieve information */
-                sieve_start = dset_contig->sieve_loc;
-                sieve_size = dset_contig->sieve_size;
-                sieve_end = sieve_start + sieve_size;
-
                 /* Read the new sieve buffer */
                 if(H5F_block_read(file, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size, dset_contig->sieve_buf) < 0)
                     HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")
@@ -1110,11 +1100,6 @@ H5D__contig_writevv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
 
                     /* Adjust sieve size */
                     dset_contig->sieve_size += len;
-
-                    /* Update local copies of sieve information */
-                    sieve_start = dset_contig->sieve_loc;
-                    sieve_size = dset_contig->sieve_size;
-                    sieve_end = sieve_start + sieve_size;
                 } /* end if */
                 /* Can't add the new data onto the existing sieve buffer */
                 else {
@@ -1146,11 +1131,6 @@ H5D__contig_writevv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
                     min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size); 
                     H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);
 
-                    /* Update local copies of sieve information */
-                    sieve_start = dset_contig->sieve_loc;
-                    sieve_size = dset_contig->sieve_size;
-                    sieve_end = sieve_start + sieve_size;
-
                     /* Check if there is any point in reading the data from the file */
                     if(dset_contig->sieve_size > len) {
                         /* Read the new sieve buffer */
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 8a7019d..339c61b 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -1362,19 +1362,10 @@ H5F__dest(H5F_t *f, hbool_t flush)
             HDONE_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "can't close property list")
 
         /* Clean up the cached VOL connector ID & info */
-        if(f->shared->vol_info) {
-            H5VL_class_t *connector;       /* Pointer to connector */
-
-            /* Retrieve the connector for the ID */
-            if(NULL == (connector = (H5VL_class_t *)H5I_object(f->shared->vol_id)))
-                /* Push error, but keep going*/
-                HDONE_ERROR(H5E_FILE, H5E_BADTYPE, FAIL, "not a VOL connector ID")
-
-            /* Free the connector info */
-            if(H5VL_free_connector_info(connector, f->shared->vol_info) < 0)
+        if(f->shared->vol_info)
+            if(H5VL_free_connector_info(f->shared->vol_id, f->shared->vol_info) < 0)
                 /* Push error, but keep going*/
                 HDONE_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to release VOL connector info object")
-        } /* end if */
         if(f->shared->vol_id > 0)
             if(H5I_dec_ref(f->shared->vol_id) < 0)
                 /* Push error, but keep going*/
diff --git a/src/H5Pfapl.c b/src/H5Pfapl.c
index bfb52ff..4b9bbdc 100644
--- a/src/H5Pfapl.c
+++ b/src/H5Pfapl.c
@@ -4907,6 +4907,43 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5P_reset_vol_class
+ *
+ * Purpose:     Change the VOL connector for a file access property class.
+ *
+ * Note:	The VOL property will be copied into the property list and
+ *		the reference count on the previous VOL will _NOT_ be decremented.
+ *		The reference count on the new VOL will _NOT_ be incremented.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Quincey Koziol
+ *              March 8, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5P_reset_vol_class(const H5P_genclass_t *pclass, const H5VL_connector_prop_t *vol_prop)
+{
+    H5VL_connector_prop_t old_vol_prop;         /* Previous VOL connector property */
+    herr_t  ret_value = SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Get the connector ID & info property */
+    if(H5P__class_get(pclass, H5F_ACS_VOL_CONN_NAME, &old_vol_prop) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get VOL connector ID & info")
+
+    /* Set the new connector ID & info property */
+    if(H5P__class_set(pclass, H5F_ACS_VOL_CONN_NAME, vol_prop) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set VOL connector ID & info")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5P_set_vol_class() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5Pset_vol
  *
  * Purpose:     Set the file VOL connector (VOL_ID) for a file access
diff --git a/src/H5Pint.c b/src/H5Pint.c
index e2ae792..79b6cf5 100644
--- a/src/H5Pint.c
+++ b/src/H5Pint.c
@@ -3061,6 +3061,116 @@ done:
 
 /*--------------------------------------------------------------------------
  NAME
+    H5P__class_get
+ PURPOSE
+    Internal routine to get a property's value from a property class.
+ USAGE
+    herr_t H5P__class_get(pclass, name, value)
+        const H5P_genclass_t *pclass; IN: Property class to find property in
+        const char *name;       IN: Name of property to get
+        void *value;            IN: Pointer to the value for the property
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+        Gets the current value for a property in a property class.  The property
+    name must exist or this routine will fail.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+        The 'get' callback routine registered for this property will _NOT_ be
+    called, this routine is designed for internal library use only!
+    
+        This routine may not be called for zero-sized properties and will
+    return an error in that case.
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5P__class_get(const H5P_genclass_t *pclass, const char *name, void *value)
+{
+    H5P_genprop_t *prop;        /* Temporary property pointer */
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Sanity check */
+    HDassert(pclass);
+    HDassert(name);
+    HDassert(value);
+
+    /* Find property in list */
+    if(NULL == (prop = (H5P_genprop_t *)H5SL_search(pclass->props, name)))
+        HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist")
+
+    /* Check for property size >0 */
+    if(0 == prop->size)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size")
+
+    /* Copy the property value */
+    HDmemcpy(value, prop->value, prop->size);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5P__class_get() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5P__class_set
+ PURPOSE
+    Internal routine to set a property's value in a property class.
+ USAGE
+    herr_t H5P__class_set(pclass, name, value)
+        const H5P_genclass_t *pclass; IN: Property class to find property in
+        const char *name;       IN: Name of property to set
+        const void *value;      IN: Pointer to the value for the property
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+        Sets a new value for a property in a property class.  The property name
+    must exist or this routine will fail.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+        The 'set' callback routine registered for this property will _NOT_ be
+    called, this routine is designed for internal library use only!
+    
+        This routine may not be called for zero-sized properties and will
+    return an error in that case.
+
+        The previous value is overwritten, not released in any way.
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5P__class_set(const H5P_genclass_t *pclass, const char *name, const void *value)
+{
+    H5P_genprop_t *prop;        /* Temporary property pointer */
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Sanity check */
+    HDassert(pclass);
+    HDassert(name);
+    HDassert(value);
+
+    /* Find property in list */
+    if(NULL == (prop = (H5P_genprop_t *)H5SL_search(pclass->props, name)))
+        HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist")
+
+    /* Check for property size >0 */
+    if(0 == prop->size)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size")
+
+    /* Copy the property value */
+    HDmemcpy(prop->value, value, prop->size);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5P__class_set() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
     H5P_exist_plist
  PURPOSE
     Internal routine to query the existance of a property in a property list.
diff --git a/src/H5Ppkg.h b/src/H5Ppkg.h
index 13f3b13..c8e5e98 100644
--- a/src/H5Ppkg.h
+++ b/src/H5Ppkg.h
@@ -151,6 +151,10 @@ H5_DLL herr_t H5P__register(H5P_genclass_t **pclass, const char *name, size_t si
     H5P_prp_close_func_t prp_close);
 H5_DLL herr_t H5P__add_prop(H5SL_t *props, H5P_genprop_t *prop);
 H5_DLL herr_t H5P__access_class(H5P_genclass_t *pclass, H5P_class_mod_t mod);
+H5_DLL herr_t H5P__class_get(const H5P_genclass_t *pclass, const char *name,
+    void *value);
+H5_DLL herr_t H5P__class_set(const H5P_genclass_t *pclass, const char *name,
+    const void *value);
 H5_DLL htri_t H5P__exist_pclass(H5P_genclass_t *pclass, const char *name);
 H5_DLL herr_t H5P__get_size_plist(const H5P_genplist_t *plist, const char *name,
     size_t *size);
diff --git a/src/H5Pprivate.h b/src/H5Pprivate.h
index 866f088..49f7a12 100644
--- a/src/H5Pprivate.h
+++ b/src/H5Pprivate.h
@@ -148,6 +148,7 @@ H5_DLLVAR const struct H5P_libclass_t H5P_CLS_OCPY[1];  /* Object copy */
 /* Forward declaration of structs used below */
 struct H5O_fill_t;
 struct H5T_t;
+struct H5VL_connector_prop_t;
 
 /* Package initialization routine */
 H5_DLL herr_t H5P_init(void);
@@ -178,6 +179,8 @@ H5_DLL const void *H5P_peek_driver_info(H5P_genplist_t *plist);
 H5_DLL herr_t H5P_set_driver(H5P_genplist_t *plist, hid_t new_driver_id,
             const void *new_driver_info);
 H5_DLL herr_t H5P_set_vol(H5P_genplist_t *plist, hid_t vol_id, const void *vol_info);
+H5_DLL herr_t H5P_reset_vol_class(const H5P_genclass_t *pclass,
+    const struct H5VL_connector_prop_t *vol_prop);
 H5_DLL herr_t H5P_set_vlen_mem_manager(H5P_genplist_t *plist,
         H5MM_allocate_t alloc_func, void *alloc_info, H5MM_free_t free_func,
         void *free_info);
diff --git a/src/H5VL.c b/src/H5VL.c
index aa276ec..6e21acb 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -29,11 +29,8 @@
 /***********/
 
 #include "H5private.h"          /* Generic Functions                    */
-#include "H5Aprivate.h"         /* Attributes                           */
 #include "H5Eprivate.h"         /* Error handling                       */
 #include "H5Iprivate.h"         /* IDs                                  */
-#include "H5MMprivate.h"        /* Memory management                    */
-#include "H5PLprivate.h"        /* Plugins                              */
 #include "H5VLpkg.h"            /* Virtual Object Layer                 */
 
 
@@ -46,29 +43,10 @@
 /* Local Typedefs */
 /******************/
 
-/* Information needed for iterating over the registered VOL connector hid_t IDs.
- * The name or value of the new VOL connector that is being registered is
- * stored in the name (or value) field and the found_id field is initialized to
- * H5I_INVALID_HID (-1).  If we find a VOL connector with the same name / value,
- * we set the found_id field to the existing ID for return to the function.
- */
-typedef struct {
-    /* IN */
-    H5VL_get_connector_kind_t kind;     /* Which kind of connector search to make */
-    union {
-        const char *name;               /* The name of the VOL connector to check */
-        H5VL_class_value_t value;       /* The value of the VOL connector to check */
-    } u;
-
-    /* OUT */
-    hid_t found_id;                     /* The connector ID, if we found a match */
-} H5VL_get_connector_ud_t;
-
 
 /********************/
 /* Local Prototypes */
 /********************/
-static int H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data);
 
 
 /*********************/
@@ -88,45 +66,6 @@ static int H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data);
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL__get_connector_cb
- *
- * Purpose:     Callback routine to search through registered VOLs
- *
- * Return:      Success:    H5_ITER_STOP if the class and op_data name
- *                          members match. H5_ITER_CONT otherwise.
- *
- *              Failure:    Can't fail
- *
- *-------------------------------------------------------------------------
- */
-static int
-H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data)
-{
-    H5VL_get_connector_ud_t *op_data = (H5VL_get_connector_ud_t *)_op_data; /* User data for callback */
-    H5VL_class_t *cls = (H5VL_class_t *)obj;
-    int ret_value = H5_ITER_CONT;     /* Callback return value */
-
-    FUNC_ENTER_STATIC_NOERR
-
-    if(H5VL_GET_CONNECTOR_BY_NAME == op_data->kind) {
-        if(0 == HDstrcmp(cls->name, op_data->u.name)) {
-            op_data->found_id = id;
-            ret_value = H5_ITER_STOP;
-        } /* end if */
-    } /* end if */
-    else {
-        HDassert(H5VL_GET_CONNECTOR_BY_VALUE == op_data->kind);
-        if(cls->value == op_data->u.value) {
-            op_data->found_id = id;
-            ret_value = H5_ITER_STOP;
-        } /* end if */
-    } /* end else */
-
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL__get_connector_cb() */
-
-
-/*-------------------------------------------------------------------------
  * Function:    H5VLregister_connector
  *
  * Purpose:     Registers a new VOL connector as a member of the virtual object
@@ -143,8 +82,7 @@ H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data)
 hid_t
 H5VLregister_connector(const H5VL_class_t *cls, hid_t vipl_id)
 {
-    H5VL_get_connector_ud_t op_data;       /* Callback info for connector search */
-    hid_t ret_value = H5I_INVALID_HID;
+    hid_t ret_value = H5I_INVALID_HID;          /* Return value */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE2("i", "*xi", cls, vipl_id);
@@ -161,25 +99,9 @@ H5VLregister_connector(const H5VL_class_t *cls, hid_t vipl_id)
     if (cls->wrap_cls.get_wrap_ctx && !cls->wrap_cls.free_wrap_ctx)
         HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "VOL connector must provide free callback for object wrapping contexts when a get callback is provided")
 
-    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
-    op_data.u.name = cls->name;
-    op_data.found_id = H5I_INVALID_HID;
-
-    /* check if connector is already registered */
-    if (H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL IDs")
-
-    /* Increment the ref count on the existing VOL connector ID, if it's already registered */
-    if(op_data.found_id != H5I_INVALID_HID) {
-        if (H5I_inc_ref(op_data.found_id, TRUE) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
-        ret_value = op_data.found_id;
-    } /* end if */
-    else {
-        /* Create a new class ID */
-        if ((ret_value = H5VL_register_connector(cls, TRUE, vipl_id)) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector")
-    } /* end else */
+    /* Register connector */
+    if((ret_value = H5VL__register_connector(cls, TRUE, vipl_id)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector")
 
 done:
     FUNC_LEAVE_API(ret_value)
@@ -203,8 +125,7 @@ done:
 hid_t
 H5VLregister_connector_by_name(const char *name, hid_t vipl_id)
 {
-    H5VL_get_connector_ud_t op_data;       /* Callback info for connector search */
-    hid_t ret_value = H5I_INVALID_HID;
+    hid_t ret_value = H5I_INVALID_HID;          /* Return value */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE2("i", "*si", name, vipl_id);
@@ -215,34 +136,9 @@ H5VLregister_connector_by_name(const char *name, hid_t vipl_id)
     if (0 == HDstrlen(name))
         HGOTO_ERROR(H5E_ARGS, H5E_UNINITIALIZED, H5I_INVALID_HID, "zero-length VOL connector name is disallowed")
 
-    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
-    op_data.u.name = name;
-    op_data.found_id = H5I_INVALID_HID;
-
-    /* Check if connector is already registered */
-    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL ids")
-
-    /* If connector alread registered, increment ref count on ID and return ID */
-    if(op_data.found_id != H5I_INVALID_HID) {
-        if(H5I_inc_ref(op_data.found_id, TRUE) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
-        ret_value = op_data.found_id;
-    } /* end if */
-    else {
-        H5PL_key_t key;
-        const H5VL_class_t *cls;
-
-        /* Try loading the connector */
-        key.vol.kind = H5VL_GET_CONNECTOR_BY_NAME;
-        key.vol.u.name = name;
-        if(NULL == (cls = (const H5VL_class_t *)H5PL_load(H5PL_TYPE_VOL, &key)))
-            HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to load VOL connector")
-
-        /* Register the connector we loaded */
-        if((ret_value = H5VL_register_connector(cls, TRUE, vipl_id)) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector ID")
-    } /* end else */
+    /* Register connector */
+    if((ret_value = H5VL__register_connector_by_name(name, TRUE, vipl_id)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector")
 
 done:
     FUNC_LEAVE_API(ret_value)
@@ -266,8 +162,7 @@ done:
 hid_t
 H5VLregister_connector_by_value(H5VL_class_value_t value, hid_t vipl_id)
 {
-    H5VL_get_connector_ud_t op_data;       /* Callback info for connector search */
-    hid_t ret_value = H5I_INVALID_HID;
+    hid_t ret_value = H5I_INVALID_HID;          /* Return value */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE2("i", "VCi", value, vipl_id);
@@ -276,34 +171,9 @@ H5VLregister_connector_by_value(H5VL_class_value_t value, hid_t vipl_id)
     if(value < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_UNINITIALIZED, H5I_INVALID_HID, "negative VOL connector value is disallowed")
 
-    op_data.kind = H5VL_GET_CONNECTOR_BY_VALUE;
-    op_data.u.value = value;
-    op_data.found_id = H5I_INVALID_HID;
-
-    /* Check if connector is already registered */
-    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL ids")
-
-    /* If connector alread registered, increment ref count on ID and return ID */
-    if(op_data.found_id != H5I_INVALID_HID) {
-        if(H5I_inc_ref(op_data.found_id, TRUE) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
-        ret_value = op_data.found_id;
-    } /* end if */
-    else {
-        H5PL_key_t key;
-        const H5VL_class_t *cls;
-
-        /* Try loading the connector */
-        key.vol.kind = H5VL_GET_CONNECTOR_BY_VALUE;
-        key.vol.u.value = value;
-        if(NULL == (cls = (const H5VL_class_t *)H5PL_load(H5PL_TYPE_VOL, &key)))
-            HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to load VOL connector")
-
-        /* Register the connector we loaded */
-        if((ret_value = H5VL_register_connector(cls, TRUE, vipl_id)) < 0)
-            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector ID")
-    } /* end else */
+    /* Register connector */
+    if((ret_value = H5VL__register_connector_by_value(value, TRUE, vipl_id)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector")
 
 done:
     FUNC_LEAVE_API(ret_value)
@@ -315,33 +185,26 @@ done:
  *
  * Purpose:     Tests whether a VOL class has been registered or not
  *
- * Return:      Positive if the VOL class has been registered
- *
- *              Zero if it is unregistered
+ * Return:      >0 if the VOL class has been registered
+ *              0 if it is unregistered
+ *              <0 on error (if the class is not a valid class ID)
  *
- *              Negative on error (if the class is not a valid class ID)
+ * Programmer:  Dana Robinson
+ *              June 17, 2017
  *
  *-------------------------------------------------------------------------
  */
 htri_t
 H5VLis_connector_registered(const char *name)
 {
-    H5VL_get_connector_ud_t op_data;       /* Callback info for connector search */
     htri_t ret_value = FALSE;           /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE1("t", "*s", name);
 
-    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
-    op_data.u.name = name;
-    op_data.found_id = H5I_INVALID_HID;
-
-    /* Check arguments */
-    if (H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "can't iterate over VOL ids")
-
-    if (op_data.found_id != H5I_INVALID_HID)
-        ret_value = TRUE;
+    /* Check if connector with this name is registered */
+    if((ret_value = H5VL__is_connector_registered(name)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't check for VOL")
 
 done:
     FUNC_LEAVE_API(ret_value)
@@ -356,30 +219,22 @@ done:
  * Return:      Positive if the VOL class has been registered
  *              Negative on error (if the class is not a valid class or not registered)
  *
+ * Programmer:  Dana Robinson
+ *              June 17, 2017
+ *
  *-------------------------------------------------------------------------
  */
 hid_t
 H5VLget_connector_id(const char *name)
 {
-    H5VL_get_connector_ud_t op_data;       /* Callback info for connector search */
     hid_t ret_value = H5I_INVALID_HID;  /* Return value */
 
     FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE1("i", "*s", name);
 
-    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
-    op_data.u.name = name;
-    op_data.found_id = H5I_INVALID_HID;
-
-    /* Check arguments */
-    if (H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL connector IDs")
-
-    if (op_data.found_id != H5I_INVALID_HID) {
-        if (H5I_inc_ref(op_data.found_id, TRUE) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
-        ret_value = op_data.found_id;
-    } /* end if */
+    /* Get connector ID with this name */
+    if((ret_value = H5VL__get_connector_id(name, TRUE)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, H5I_INVALID_HID, "can't get VOL id")
 
 done:
     FUNC_LEAVE_API(ret_value)
@@ -406,7 +261,8 @@ H5VLget_connector_name(hid_t obj_id, char *name/*out*/, size_t size)
     FUNC_ENTER_API(FAIL)
     H5TRACE3("Zs", "ixz", obj_id, name, size);
 
-    if ((ret_value = H5VL_get_connector_name(obj_id, name, size)) < 0)
+    /* Call internal routine */
+    if((ret_value = H5VL__get_connector_name(obj_id, name, size)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Can't get connector name")
 
 done:
diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index 5a5d9ee..d77c9f6 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -506,20 +506,25 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_free_connector_info(const H5VL_class_t *connector, void *info)
+H5VL_free_connector_info(hid_t connector_id, void *info)
 {
-    herr_t ret_value = SUCCEED;   /* Return value */
+    H5VL_class_t *cls;                  /* VOL connector's class struct */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    /* Sanity checks */
-    HDassert(connector);
+    /* Sanity check */
+    HDassert(connector_id > 0);
+
+    /* Check args and get class pointer */
+    if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_VOL, H5E_BADTYPE, FAIL, "not a VOL connector ID")
 
     /* Only free info object, if it's non-NULL */
     if(info) {
         /* Allow the connector to free info or do it ourselves */
-        if(connector->info_cls.free) {
-            if((connector->info_cls.free)(info) < 0)
+        if(cls->info_cls.free) {
+            if((cls->info_cls.free)(info) < 0)
                 HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "connector info free request failed")
         } /* end if */
         else
@@ -544,18 +549,13 @@ done:
 herr_t
 H5VLfree_connector_info(hid_t connector_id, void *info)
 {
-    H5VL_class_t *cls;                  /* VOL connector's class struct */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_API_NOINIT
     H5TRACE2("e", "i*x", connector_id, info);
 
-    /* Check args and get class pointer */
-    if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL connector ID")
-
     /* Free the VOL connector info object */
-    if(H5VL_free_connector_info(cls, info) < 0)
+    if(H5VL_free_connector_info(connector_id, info) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to release VOL connector info object")
 
 done:
@@ -623,24 +623,9 @@ H5VLconnector_str_to_info(const char *str, hid_t connector_id, void **info)
     FUNC_ENTER_API_NOINIT
     H5TRACE3("e", "*si**x", str, connector_id, info);
 
-    /* Only deserialize string, if it's non-NULL */
-    if(str) {
-        H5VL_class_t *cls;                  /* VOL connector's class struct */
-
-        /* Check args and get class pointer */
-        if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL connector ID")
-
-        /* Allow the connector to deserialize info */
-        if(cls->info_cls.from_str) {
-            if((cls->info_cls.from_str)(str, info) < 0)
-                HGOTO_ERROR(H5E_VOL, H5E_CANTUNSERIALIZE, FAIL, "can't deserialize connector info")
-        } /* end if */
-        else
-            *info = NULL;
-    } /* end if */
-    else
-        *info = NULL;
+    /* Call internal routine */
+    if(H5VL__connector_str_to_info(str, connector_id, info) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTDECODE, FAIL, "can't deserialize connector info")
 
 done:
     FUNC_LEAVE_API_NOINIT(ret_value)
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 5aa25d2..3d1be61 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -29,14 +29,19 @@
 /* Headers */
 /***********/
 
-#include "H5private.h"          /* Generic Functions                                */
-#include "H5CXprivate.h"        /* API Contexts                                     */
-#include "H5Eprivate.h"         /* Error handling                                   */
-#include "H5FLprivate.h"        /* Free lists                                       */
-#include "H5Iprivate.h"         /* IDs                                              */
-#include "H5MMprivate.h"        /* Memory management                                */
-#include "H5Tprivate.h"         /* Datatypes                                        */
-#include "H5VLpkg.h"            /* Virtual Object Layer                             */
+#include "H5private.h"          /* Generic Functions                    */
+#include "H5CXprivate.h"        /* API Contexts                         */
+#include "H5Eprivate.h"         /* Error handling                       */
+#include "H5FLprivate.h"        /* Free lists                           */
+#include "H5Iprivate.h"         /* IDs                                  */
+#include "H5MMprivate.h"        /* Memory management                    */
+#include "H5PLprivate.h"        /* Plugins                              */
+#include "H5Tprivate.h"         /* Datatypes                            */
+#include "H5VLpkg.h"            /* Virtual Object Layer                 */
+
+/* VOL connectors */
+#include "H5VLnative.h"         /* Native VOL connector                 */
+#include "H5VLpassthru.h"       /* Pass-through VOL connector           */
 
 
 /****************/
@@ -55,6 +60,24 @@ typedef struct H5VL_wrap_ctx_t {
     void *obj_wrap_ctx;         /* "wrap context" for outermost connector */
 } H5VL_wrap_ctx_t;
 
+/* Information needed for iterating over the registered VOL connector hid_t IDs.
+ * The name or value of the new VOL connector that is being registered is
+ * stored in the name (or value) field and the found_id field is initialized to
+ * H5I_INVALID_HID (-1).  If we find a VOL connector with the same name / value,
+ * we set the found_id field to the existing ID for return to the function.
+ */
+typedef struct {
+    /* IN */
+    H5VL_get_connector_kind_t kind;     /* Which kind of connector search to make */
+    union {
+        const char *name;               /* The name of the VOL connector to check */
+        H5VL_class_value_t value;       /* The value of the VOL connector to check */
+    } u;
+
+    /* OUT */
+    hid_t found_id;                     /* The connector ID, if we found a match */
+} H5VL_get_connector_ud_t;
+
 
 /********************/
 /* Package Typedefs */
@@ -65,6 +88,8 @@ typedef struct H5VL_wrap_ctx_t {
 /* Local Prototypes */
 /********************/
 static herr_t H5VL__free_cls(H5VL_class_t *cls);
+static int H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data);
+static herr_t H5VL__set_def_conn(void);
 static void *H5VL__wrap_obj(void *obj, H5I_type_t obj_type);
 static H5VL_object_t *H5VL__new_vol_obj(H5I_type_t type, void *object,
     H5VL_t *vol_connector, hbool_t wrap_obj);
@@ -83,6 +108,7 @@ hbool_t H5_PKG_INIT_VAR = FALSE;
 /* Library Private Variables */
 /*****************************/
 
+
 /*******************/
 /* Local Variables */
 /*******************/
@@ -107,21 +133,27 @@ H5FL_DEFINE(H5VL_object_t);
 /* Declare a free list to manage the H5VL_wrap_ctx_t struct */
 H5FL_DEFINE_STATIC(H5VL_wrap_ctx_t);
 
+/* Default VOL connector */
+static H5VL_connector_prop_t H5VL_def_conn_s = {-1, NULL};
+
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_init
+ * Function:    H5VL_init_phase1
  *
- * Purpose:     Initialize the interface from some other package
+ * Purpose:     Initialize the interface from some other package.  This should
+ *		be followed with a call to H5VL_init_phase2 after the H5P
+ *		interface is completely set up, finish setting up the H5VL
+ *		information.
  *
- * Return:      Success:    Non-negative
  *
+ * Return:      Success:    Non-negative
  *              Failure:    Negative
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_init(void)
+H5VL_init_phase1(void)
 {
     herr_t ret_value = SUCCEED;   /* Return value */
 
@@ -131,7 +163,36 @@ H5VL_init(void)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_init() */
+} /* end H5VL_init_phase1() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL_init_phase2
+ *
+ * Purpose:     Finish initializing the interface from some other package.
+ *
+ * Note:	This is broken out as a separate routine to avoid a circular
+ *		reference with the H5P package.
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_init_phase2(void)
+{
+    herr_t ret_value = SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Set up the default VOL connector in the default FAPL */
+    if(H5VL__set_def_conn() < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTSET, FAIL, "unable to set default VOL connector")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_init_phase2() */
 
 
 /*-------------------------------------------------------------------------
@@ -148,12 +209,12 @@ done:
 herr_t
 H5VL__init_package(void)
 {
-    herr_t ret_value = SUCCEED;   /* Return value */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_PACKAGE
 
     /* Initialize the atom group for the VL IDs */
-    if (H5I_register_type(H5I_VOL_CLS) < 0)
+    if(H5I_register_type(H5I_VOL_CLS) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to initialize H5VL interface")
 
 done:
@@ -180,17 +241,27 @@ H5VL_term_package(void)
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
     if(H5_PKG_INIT_VAR) {
-        if (H5I_nmembers(H5I_VOL) > 0) {
-            (void)H5I_clear_type(H5I_VOL, FALSE, FALSE);
+        if(H5VL_def_conn_s.connector_id > 0) {
+            /* Release the default VOL connector */
+            (void)H5VL_conn_free(&H5VL_def_conn_s);
+            H5VL_def_conn_s.connector_id = -1;
+            H5VL_def_conn_s.connector_info = NULL;
             n++;
         } /* end if */
         else {
-            /* Destroy the VOL connector ID group */
-            n += (H5I_dec_type_ref(H5I_VOL) > 0);
-
-            /* Mark interface as closed */
-            if (0 == n)
-                H5_PKG_INIT_VAR = FALSE;
+            if(H5I_nmembers(H5I_VOL) > 0) {
+                /* Unregister all VOL connectors */
+                (void)H5I_clear_type(H5I_VOL, FALSE, FALSE);
+                n++;
+            } /* end if */
+            else {
+                /* Destroy the VOL connector ID group */
+                n += (H5I_dec_type_ref(H5I_VOL) > 0);
+
+                /* Mark interface as closed */
+                if(0 == n)
+                    H5_PKG_INIT_VAR = FALSE;
+            } /* end else */
         } /* end else */
     } /* end if */
 
@@ -234,6 +305,182 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5VL__get_connector_cb
+ *
+ * Purpose:     Callback routine to search through registered VOLs
+ *
+ * Return:      Success:    H5_ITER_STOP if the class and op_data name
+ *                          members match. H5_ITER_CONT otherwise.
+ *              Failure:    Can't fail
+ *
+ * Programmer:  Dana Robinson
+ *              June 22, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5VL__get_connector_cb(void *obj, hid_t id, void *_op_data)
+{
+    H5VL_get_connector_ud_t *op_data = (H5VL_get_connector_ud_t *)_op_data; /* User data for callback */
+    H5VL_class_t *cls = (H5VL_class_t *)obj;
+    int ret_value = H5_ITER_CONT;     /* Callback return value */
+
+    FUNC_ENTER_STATIC_NOERR
+
+    if(H5VL_GET_CONNECTOR_BY_NAME == op_data->kind) {
+        if(0 == HDstrcmp(cls->name, op_data->u.name)) {
+            op_data->found_id = id;
+            ret_value = H5_ITER_STOP;
+        } /* end if */
+    } /* end if */
+    else {
+        HDassert(H5VL_GET_CONNECTOR_BY_VALUE == op_data->kind);
+        if(cls->value == op_data->u.value) {
+            op_data->found_id = id;
+            ret_value = H5_ITER_STOP;
+        } /* end if */
+    } /* end else */
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__get_connector_cb() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__set_def_conn
+ *
+ * Purpose:     Parses a string that contains the default VOL connector for
+ *              the library.
+ *
+ * Note:	Usually from the environment variable "HDF5_VOL_CONNECTOR",
+ *		but could be from elsewhere.
+ *
+ * Return:      Success:    0
+ *              Failure:    -1
+ *
+ * Programmer:  Jordan Henderson
+ *              November 2018
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5VL__set_def_conn(void)
+{
+    H5P_genplist_t *def_fapl;           /* Default file access property list */
+    H5P_genclass_t *def_fapclass;       /* Default file access property class */
+    const char *env_var;                /* Environment variable for default VOL connector */
+    char *buf = NULL;                   /* Buffer for tokenizing string */
+    hid_t connector_id = -1;            /* VOL conntector ID */
+    void *vol_info = NULL;              /* VOL connector info */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(H5VL_def_conn_s.connector_id == (-1));
+    HDassert(H5VL_def_conn_s.connector_info == NULL);
+
+    /* Check for environment variable set */
+    env_var = HDgetenv("HDF5_VOL_CONNECTOR");
+
+    /* Only parse the string if it's set */
+    if(env_var && *env_var) {
+        char *lasts = NULL;             /* Context pointer for strtok_r() call */
+        const char *tok = NULL;         /* Token from strtok_r call */
+        htri_t connector_is_registered; /* Whether connector is already registered */
+
+        /* Duplicate the string to parse, as it is modified as we go */
+        if(NULL == (buf = H5MM_strdup(env_var)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, FAIL, "can't allocate memory for environment variable string")
+
+        /* Get the first 'word' of the environment variable.
+         * If it's nothing (environment variable was whitespace) return error.
+         */
+        if(NULL == (tok = HDstrtok_r(buf, " \t\n\r", &lasts)))
+            HGOTO_ERROR(H5E_VOL, H5E_BADVALUE, FAIL, "VOL connector environment variable set empty?")
+
+        /* First, check to see if the connector is already registered */
+        if((connector_is_registered = H5VL__is_connector_registered(tok)) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't check if VOL connector already registered")
+        else if(connector_is_registered) {
+            /* Retrieve the ID of the already-registered VOL connector */
+            if((connector_id = H5VL__get_connector_id(tok, FALSE)) < 0)
+                HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "can't get VOL connector ID")
+        } /* end else-if */
+        else {
+            /* Check for VOL connectors that ship with the library */
+            if(!HDstrcmp(tok, "native")) {
+                connector_id = H5VL_NATIVE;
+                if(H5I_inc_ref(connector_id, FALSE) < 0)
+                    HGOTO_ERROR(H5E_VOL, H5E_CANTINC, FAIL, "can't increment VOL connector refcount")
+            } /* end if */
+            else if(!HDstrcmp(tok, "pass_through")) {
+                connector_id = H5VL_PASSTHRU;
+                if(H5I_inc_ref(connector_id, FALSE) < 0)
+                    HGOTO_ERROR(H5E_VOL, H5E_CANTINC, FAIL, "can't increment VOL connector refcount")
+            } /* end else-if */
+            else {
+                /* Register the VOL connector */
+                /* (NOTE: No provisions for vipl_id currently) */
+                if((connector_id = H5VL__register_connector_by_name(tok, FALSE, H5P_DEFAULT)) < 0)
+                    HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, FAIL, "can't register connector")
+            } /* end else */
+        } /* end else */
+
+        /* Was there any connector info specified in the environment variable? */
+        if(NULL != (tok = HDstrtok_r(NULL, " \t\n\r", &lasts)))
+            if(H5VL__connector_str_to_info(tok, connector_id, &vol_info) < 0)
+                HGOTO_ERROR(H5E_VOL, H5E_CANTDECODE, FAIL, "can't deserialize connector info")
+
+        /* Set the default VOL connector */
+        H5VL_def_conn_s.connector_id = connector_id;
+        H5VL_def_conn_s.connector_info = vol_info;
+    } /* end if */
+    else {
+        /* Set the default VOL connector */
+        H5VL_def_conn_s.connector_id = H5_DEFAULT_VOL;
+        H5VL_def_conn_s.connector_info = NULL;
+
+        /* Increment the ref count on the default connector */
+        if(H5I_inc_ref(H5VL_def_conn_s.connector_id, FALSE) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, FAIL, "can't increment VOL connector refcount")
+    } /* end else */
+
+    /* Get default file access pclass */
+    if(NULL == (def_fapclass = (H5P_genclass_t *)H5I_object(H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_VOL, H5E_BADATOM, FAIL, "can't find object for default file access property class ID")
+
+    /* Change the default VOL for the default file access pclass */
+    if(H5P_reset_vol_class(def_fapclass, &H5VL_def_conn_s) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTSET, FAIL, "can't set default VOL connector for default file access property class")
+
+    /* Get default file access plist */
+    if(NULL == (def_fapl = (H5P_genplist_t *)H5I_object(H5P_FILE_ACCESS_DEFAULT)))
+        HGOTO_ERROR(H5E_VOL, H5E_BADATOM, FAIL, "can't find object for default fapl ID")
+
+    /* Change the default VOL for the default FAPL */
+    if(H5P_set_vol(def_fapl, H5VL_def_conn_s.connector_id, H5VL_def_conn_s.connector_info) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTSET, FAIL, "can't set default VOL connector for default FAPL")
+
+done:
+    /* Clean up on error */
+    if(ret_value < 0) {
+        if(vol_info)
+            if(H5VL_free_connector_info(connector_id, vol_info) < 0)
+                HDONE_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "can't free VOL connector info")
+        if(connector_id >= 0)
+            /* The H5VL_class_t struct will be freed by this function */
+            if(H5I_dec_ref(connector_id) < 0)
+                HDONE_ERROR(H5E_VOL, H5E_CANTDEC, FAIL, "unable to unregister VOL connector")
+    } /* end if */
+
+    /* Clean up */
+    H5MM_xfree(buf);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__set_def_conn() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5VL__wrap_obj
  *
  * Purpose:     Wraps a library object with possible VOL connector wrappers, to
@@ -393,29 +640,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_conn_free(const H5VL_connector_prop_t *info)
+H5VL_conn_free(const H5VL_connector_prop_t *connector_prop)
 {
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(info) {
+    if(connector_prop) {
         /* Free the connector info (if it exists) and decrement the ID */
-        if(info->connector_id > 0) {
-            if(info->connector_info) {
-                H5VL_class_t *connector;       /* Pointer to connector */
-
-                /* Retrieve the connector for the ID */
-                if(NULL == (connector = (H5VL_class_t *)H5I_object(info->connector_id)))
-                    HGOTO_ERROR(H5E_VOL, H5E_BADTYPE, FAIL, "not a VOL connector ID")
-
+        if(connector_prop->connector_id > 0) {
+            if(connector_prop->connector_info)
                 /* Free the connector info */
-                if(H5VL_free_connector_info(connector, (void *)info->connector_info) < 0)        /* Casting away const OK - QAK */
+                if(H5VL_free_connector_info(connector_prop->connector_id, (void *)connector_prop->connector_info) < 0)        /* Casting away const OK - QAK */
                     HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to release VOL connector info object")
-            } /* end if */
 
             /* Decrement reference count for connector ID */
-            if(H5I_dec_ref(info->connector_id) < 0)
+            if(H5I_dec_ref(connector_prop->connector_id) < 0)
                 HGOTO_ERROR(H5E_VOL, H5E_CANTDEC, FAIL, "can't decrement reference count for connector ID")
         } /* end if */
     } /* end if */
@@ -595,6 +835,9 @@ done:
  *
  *              Failure:    H5I_INVALID_HID 
  *
+ * Programmer:  Dana Robinson
+ *              June 22, 2017
+ *
  *-------------------------------------------------------------------------
  */
 hid_t
@@ -610,7 +853,7 @@ H5VL_register_connector(const void *_cls, hbool_t app_ref, hid_t vipl_id)
     HDassert(cls);
 
     /* Copy the class structure so the caller can reuse or free it */
-    if (NULL == (saved = H5FL_CALLOC(H5VL_class_t)))
+    if(NULL == (saved = H5FL_MALLOC(H5VL_class_t)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, H5I_INVALID_HID, "memory allocation failed for VOL connector class struct")
     HDmemcpy(saved, cls, sizeof(H5VL_class_t));
     if(NULL == (saved->name = H5MM_strdup(cls->name)))
@@ -621,23 +864,319 @@ H5VL_register_connector(const void *_cls, hbool_t app_ref, hid_t vipl_id)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to init VOL connector")
 
     /* Create the new class ID */
-    if ((ret_value = H5I_register(H5I_VOL, saved, app_ref)) < 0)
+    if((ret_value = H5I_register(H5I_VOL, saved, app_ref)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector ID")
 
 done:
-    if (ret_value < 0 && saved) {
-        if (saved->name)
+    if(ret_value < 0 && saved) {
+        if(saved->name)
             H5MM_xfree((void *)(saved->name));  /* Casting away const OK -QAK */
 
         H5FL_FREE(H5VL_class_t, saved);
-    }
+    } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_register_connector() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_get_connector_name
+ * Function:    H5VL__register_connector
+ *
+ * Purpose:     Registers a new VOL connector as a member of the virtual object
+ *              layer class.
+ *
+ * Return:      Success:    A VOL connector ID which is good until the
+ *                          library is closed or the connector is
+ *                          unregistered.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ * Programmer:  Dana Robinson
+ *              June 22, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL__register_connector(const H5VL_class_t *cls, hbool_t app_ref, hid_t vipl_id)
+{
+    H5VL_get_connector_ud_t op_data;        /* Callback info for connector search */
+    hid_t ret_value = H5I_INVALID_HID;      /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Set up op data for iteration */
+    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
+    op_data.u.name = cls->name;
+    op_data.found_id = H5I_INVALID_HID;
+
+    /* Check if connector is already registered */
+    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL IDs")
+
+    /* Increment the ref count on the existing VOL connector ID, if it's already registered */
+    if(op_data.found_id != H5I_INVALID_HID) {
+        if(H5I_inc_ref(op_data.found_id, app_ref) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
+        ret_value = op_data.found_id;
+    } /* end if */
+    else {
+        /* Create a new class ID */
+        if((ret_value = H5VL_register_connector(cls, app_ref, vipl_id)) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector")
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__register_connector() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__register_connector_by_name
+ *
+ * Purpose:     Registers a new VOL connector as a member of the virtual object
+ *              layer class.
+ *
+ * Return:      Success:    A VOL connector ID which is good until the
+ *                          library is closed or the connector is
+ *                          unregistered.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ * Programmer:  Dana Robinson
+ *              June 22, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL__register_connector_by_name(const char *name, hbool_t app_ref, hid_t vipl_id)
+{
+    H5VL_get_connector_ud_t op_data;        /* Callback info for connector search */
+    hid_t ret_value = H5I_INVALID_HID;      /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Set up op data for iteration */
+    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
+    op_data.u.name = name;
+    op_data.found_id = H5I_INVALID_HID;
+
+    /* Check if connector is already registered */
+    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL ids")
+
+    /* If connector alread registered, increment ref count on ID and return ID */
+    if(op_data.found_id != H5I_INVALID_HID) {
+        if(H5I_inc_ref(op_data.found_id, app_ref) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
+        ret_value = op_data.found_id;
+    } /* end if */
+    else {
+        H5PL_key_t key;
+        const H5VL_class_t *cls;
+
+        /* Try loading the connector */
+        key.vol.kind = H5VL_GET_CONNECTOR_BY_NAME;
+        key.vol.u.name = name;
+        if(NULL == (cls = (const H5VL_class_t *)H5PL_load(H5PL_TYPE_VOL, &key)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to load VOL connector")
+
+        /* Register the connector we loaded */
+        if((ret_value = H5VL_register_connector(cls, app_ref, vipl_id)) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector ID")
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__register_connector_by_name() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__register_connector_by_value
+ *
+ * Purpose:     Registers a new VOL connector as a member of the virtual object
+ *              layer class.
+ *
+ * Return:      Success:    A VOL connector ID which is good until the
+ *                          library is closed or the connector is
+ *                          unregistered.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ * Programmer:  Dana Robinson
+ *              June 22, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL__register_connector_by_value(H5VL_class_value_t value, hbool_t app_ref, hid_t vipl_id)
+{
+    H5VL_get_connector_ud_t op_data;        /* Callback info for connector search */
+    hid_t ret_value = H5I_INVALID_HID;      /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Set up op data for iteration */
+    op_data.kind = H5VL_GET_CONNECTOR_BY_VALUE;
+    op_data.u.value = value;
+    op_data.found_id = H5I_INVALID_HID;
+
+    /* Check if connector is already registered */
+    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL ids")
+
+    /* If connector alread registered, increment ref count on ID and return ID */
+    if(op_data.found_id != H5I_INVALID_HID) {
+        if(H5I_inc_ref(op_data.found_id, app_ref) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
+        ret_value = op_data.found_id;
+    } /* end if */
+    else {
+        H5PL_key_t key;
+        const H5VL_class_t *cls;
+
+        /* Try loading the connector */
+        key.vol.kind = H5VL_GET_CONNECTOR_BY_VALUE;
+        key.vol.u.value = value;
+        if(NULL == (cls = (const H5VL_class_t *)H5PL_load(H5PL_TYPE_VOL, &key)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to load VOL connector")
+
+        /* Register the connector we loaded */
+        if((ret_value = H5VL_register_connector(cls, app_ref, vipl_id)) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL connector ID")
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__register_connector_by_value() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__is_connector_registered
+ *
+ * Purpose:     Checks if a connector with a particular name is registered.
+ *
+ * Return:      Success:    0
+ *              Failure:    -1
+ *
+ * Programmer:  Dana Robinson
+ *              June 17, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5VL__is_connector_registered(const char *name)
+{
+    H5VL_get_connector_ud_t op_data;    /* Callback info for connector search */
+    htri_t ret_value = FALSE;           /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Set up op data for iteration */
+    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
+    op_data.u.name = name;
+    op_data.found_id = H5I_INVALID_HID;
+
+    /* Find connector with name */
+    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "can't iterate over VOL connectors")
+
+    /* Found a connector with that name */
+    if(op_data.found_id != H5I_INVALID_HID)
+        ret_value = TRUE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__is_connector_registered() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__get_connector_id
+ *
+ * Purpose:     Retrieves the ID for a registered VOL connector.
+ *
+ * Return:      Positive if the VOL class has been registered
+ *              Negative on error (if the class is not a valid class or not registered)
+ *
+ * Programmer:  Dana Robinson
+ *              June 17, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL__get_connector_id(const char *name, hbool_t is_api)
+{
+    H5VL_get_connector_ud_t op_data;        /* Callback info for connector search */
+    hid_t ret_value = H5I_INVALID_HID;      /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Set up op data for iteration */
+    op_data.kind = H5VL_GET_CONNECTOR_BY_NAME;
+    op_data.u.name = name;
+    op_data.found_id = H5I_INVALID_HID;
+
+    /* Find connector with name */
+    if(H5I_iterate(H5I_VOL, H5VL__get_connector_cb, &op_data, TRUE) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_BADITER, H5I_INVALID_HID, "can't iterate over VOL connectors")
+
+    /* Found a connector with that name */
+    if(op_data.found_id != H5I_INVALID_HID) {
+        if(H5I_inc_ref(op_data.found_id, is_api) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL connector")
+        ret_value = op_data.found_id;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__get_connector_id() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__connector_str_to_info
+ *
+ * Purpose:     Deserializes a string into a connector's info object
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              March 2, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL__connector_str_to_info(const char *str, hid_t connector_id, void **info)
+{
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Only deserialize string, if it's non-NULL */
+    if(str) {
+        H5VL_class_t *cls;                  /* VOL connector's class struct */
+
+        /* Check args and get class pointer */
+        if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
+            HGOTO_ERROR(H5E_VOL, H5E_BADTYPE, FAIL, "not a VOL connector ID")
+
+        /* Allow the connector to deserialize info */
+        if(cls->info_cls.from_str) {
+            if((cls->info_cls.from_str)(str, info) < 0)
+                HGOTO_ERROR(H5E_VOL, H5E_CANTUNSERIALIZE, FAIL, "can't deserialize connector info")
+        } /* end if */
+        else
+            *info = NULL;
+    } /* end if */
+    else
+        *info = NULL;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__connector_str_to_info() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__get_connector_name
  *
  * Purpose:     Private version of H5VLget_connector_name
  *
@@ -647,14 +1186,14 @@ done:
  *-------------------------------------------------------------------------
  */
 ssize_t
-H5VL_get_connector_name(hid_t id, char *name /*out*/, size_t size)
+H5VL__get_connector_name(hid_t id, char *name /*out*/, size_t size)
 {
     H5VL_object_t       *vol_obj;
     const H5VL_class_t  *cls;
     size_t              len;
     ssize_t             ret_value = -1;
 
-    FUNC_ENTER_NOAPI(FAIL)
+    FUNC_ENTER_PACKAGE
 
     /* get the object pointer */
     if (NULL == (vol_obj = H5VL_vol_object(id)))
@@ -674,7 +1213,7 @@ H5VL_get_connector_name(hid_t id, char *name /*out*/, size_t size)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_get_connector_name() */
+} /* end H5VL__get_connector_name() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5VLpassthru.c b/src/H5VLpassthru.c
index fe72000..a4c85cc 100644
--- a/src/H5VLpassthru.c
+++ b/src/H5VLpassthru.c
@@ -20,6 +20,11 @@
  *              include _any_ private HDF5 header files.  This connector should
  *              therefore only make public HDF5 API calls and use standard C /
  *              POSIX calls.
+ *
+ *              Note that the HDF5 error stack must be preserved on code paths
+ *              that could be invoked when the underlying VOL connector's
+ *              callback can fail.
+ *
  */
 
 
@@ -297,6 +302,9 @@ H5VL_pass_through_new_obj(void *under_obj, hid_t under_vol_id)
  *
  * Purpose:     Release a pass through object
  *
+ * Note:	Take care to preserve the current HDF5 error stack
+ *		when calling HDF5 API calls.
+ *
  * Return:      Success:    0
  *              Failure:    -1
  *
@@ -308,7 +316,14 @@ H5VL_pass_through_new_obj(void *under_obj, hid_t under_vol_id)
 static herr_t
 H5VL_pass_through_free_obj(H5VL_pass_through_t *obj)
 {
+    hid_t err_id;
+
+    err_id = H5Eget_current_stack();
+
     H5Idec_ref(obj->under_vol_id);
+
+    H5Eset_current_stack(err_id);
+
     free(obj);
 
     return 0;
@@ -332,11 +347,8 @@ H5VL_pass_through_free_obj(H5VL_pass_through_t *obj)
 hid_t
 H5VL_pass_through_register(void)
 {
-    /* Clear the error stack */
-    H5Eclear2(H5E_DEFAULT);
-
     /* Singleton register the pass-through VOL connector ID */
-    if(H5I_VOL != H5Iget_type(H5VL_PASSTHRU_g))
+    if(H5VL_PASSTHRU_g < 0)
         H5VL_PASSTHRU_g = H5VLregister_connector(&H5VL_pass_through_g, H5P_DEFAULT);
 
     return H5VL_PASSTHRU_g;
@@ -476,6 +488,9 @@ H5VL_pass_through_info_cmp(int *cmp_value, const void *_info1, const void *_info
  *
  * Purpose:     Release an info object for the connector.
  *
+ * Note:	Take care to preserve the current HDF5 error stack
+ *		when calling HDF5 API calls.
+ *
  * Return:      Success:    0
  *              Failure:    -1
  *
@@ -485,16 +500,21 @@ static herr_t
 H5VL_pass_through_info_free(void *_info)
 {
     H5VL_pass_through_info_t *info = (H5VL_pass_through_info_t *)_info;
+    hid_t err_id;
 
 #ifdef ENABLE_PASSTHRU_LOGGING
     printf("------- PASS THROUGH VOL INFO Free\n");
 #endif
 
+    err_id = H5Eget_current_stack();
+
     /* Release underlying VOL ID and info */
     if(info->under_vol_info)
         H5VLfree_connector_info(info->under_vol_id, info->under_vol_info);
     H5Idec_ref(info->under_vol_id);
 
+    H5Eset_current_stack(err_id);
+
     /* Free pass through info object itself */
     free(info);
 
@@ -695,6 +715,9 @@ H5VL_pass_through_wrap_object(void *obj, H5I_type_t obj_type, void *_wrap_ctx)
  *
  * Purpose:     Release a "wrapper context" for an object
  *
+ * Note:	Take care to preserve the current HDF5 error stack
+ *		when calling HDF5 API calls.
+ *
  * Return:      Success:    0
  *              Failure:    -1
  *
@@ -704,16 +727,21 @@ static herr_t
 H5VL_pass_through_free_wrap_ctx(void *_wrap_ctx)
 {
     H5VL_pass_through_wrap_ctx_t *wrap_ctx = (H5VL_pass_through_wrap_ctx_t *)_wrap_ctx;
+    hid_t err_id;
 
 #ifdef ENABLE_PASSTHRU_LOGGING
     printf("------- PASS THROUGH VOL WRAP CTX Free\n");
 #endif
 
+    err_id = H5Eget_current_stack();
+
     /* Release underlying VOL ID and wrap context */
     if(wrap_ctx->under_wrap_ctx)
         H5VLfree_wrap_ctx(wrap_ctx->under_wrap_ctx, wrap_ctx->under_vol_id);
     H5Idec_ref(wrap_ctx->under_vol_id);
 
+    H5Eset_current_stack(err_id);
+
     /* Free pass through wrap context object itself */
     free(wrap_ctx);
 
diff --git a/src/H5VLpkg.h b/src/H5VLpkg.h
index bbdb0cc..69e51c2 100644
--- a/src/H5VLpkg.h
+++ b/src/H5VLpkg.h
@@ -28,21 +28,36 @@
 
 /* Other private headers needed by this file */
 
+
 /**************************/
 /* Package Private Macros */
 /**************************/
 
+
 /****************************/
 /* Package Private Typedefs */
 /****************************/
 
+
 /*****************************/
 /* Package Private Variables */
 /*****************************/
 
+
 /******************************/
 /* Package Private Prototypes */
 /******************************/
+H5_DLL hid_t H5VL__register_connector(const H5VL_class_t *cls, hbool_t app_ref,
+    hid_t vipl_id);
+H5_DLL hid_t H5VL__register_connector_by_name(const char *name, hbool_t app_ref,
+    hid_t vipl_id);
+H5_DLL hid_t H5VL__register_connector_by_value(H5VL_class_value_t value,
+    hbool_t app_ref, hid_t vipl_id);
+H5_DLL htri_t H5VL__is_connector_registered(const char *name);
+H5_DLL hid_t H5VL__get_connector_id(const char *name, hbool_t is_api);
+H5_DLL herr_t H5VL__connector_str_to_info(const char *str, hid_t connector_id,
+    void **info);
+H5_DLL ssize_t H5VL__get_connector_name(hid_t id, char *name/*out*/, size_t size);
 
 #endif /* _H5VLpkg_H */
 
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index 283c77a..6b948f6 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -18,10 +18,12 @@
 
 /* Private headers needed by this file */
 
+
 /**************************/
 /* Library Private Macros */
 /**************************/
 
+
 /****************************/
 /* Library Private Typedefs */
 /****************************/
@@ -62,14 +64,14 @@ typedef enum H5VL_get_connector_kind_t {
 /******************************/
 
 /* Utility functions */
-H5_DLL herr_t H5VL_init(void);
+H5_DLL herr_t H5VL_init_phase1(void);
+H5_DLL herr_t H5VL_init_phase2(void);
 H5_DLL herr_t H5VL_cmp_connector_cls(int *cmp_value, const H5VL_class_t *cls1, const H5VL_class_t *cls2);
 H5_DLL herr_t H5VL_conn_copy(H5VL_connector_prop_t *value);
 H5_DLL herr_t H5VL_conn_free(const H5VL_connector_prop_t *info);
 
 /* Functions that deal with VOL connectors */
 H5_DLL hid_t H5VL_register_connector(const void *cls, hbool_t app_ref, hid_t vipl_id);
-H5_DLL ssize_t H5VL_get_connector_name(hid_t id, char *name/*out*/, size_t size);
 
 /* NOTE:    The object and ID functions below deal in VOL objects (i.e.;
  *          H5VL_object_t). Similar non-VOL calls exist in H5Iprivate.h. Use
@@ -112,7 +114,7 @@ H5_DLL int H5VL_copy_connector_info(const H5VL_class_t *connector, void **dst_in
     const void *src_info);
 H5_DLL herr_t H5VL_cmp_connector_info(const H5VL_class_t *connector, int *cmp_value,
     const void *info1, const void *info2);
-H5_DLL herr_t H5VL_free_connector_info(const H5VL_class_t *connector, void *info);
+H5_DLL herr_t H5VL_free_connector_info(hid_t connector_id, void *info);
 
 /* Attribute functions */
 H5_DLL void *H5VL_attr_create(const H5VL_object_t *vol_obj, const H5VL_loc_params_t *loc_params, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);