Merge remote-tracking branch 'hdf5/develop' into add-werror-and-squash-some

20 files changed, 595 insertions, 141 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9bb73a9..c794c1a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -254,7 +254,7 @@ set (H5FD_HDRS
     ${HDF5_SRC_DIR}/H5FDmulti.h
     ${HDF5_SRC_DIR}/H5FDpublic.h
     ${HDF5_SRC_DIR}/H5FDros3.h
-    ${HDF5_SRC_DIR}/H5FDs3comms.c
+    ${HDF5_SRC_DIR}/H5FDs3comms.h
     ${HDF5_SRC_DIR}/H5FDsec2.h
     ${HDF5_SRC_DIR}/H5FDstdio.h
     ${HDF5_SRC_DIR}/H5FDwindows.h
diff --git a/src/H5CX.c b/src/H5CX.c
index 96c1d72..649bd8f 100644
--- a/src/H5CX.c
+++ b/src/H5CX.c
@@ -181,6 +181,10 @@ typedef struct H5CX_t {
     hid_t dxpl_id;              /* DXPL ID for API operation */
     H5P_genplist_t *dxpl;       /* Dataset Transfer Property List */
 
+    /* LCPL */
+    hid_t lcpl_id;              /* LCPL ID for API operation */
+    H5P_genplist_t *lcpl;       /* Link Creation Property List */
+
     /* LAPL */
     hid_t lapl_id;              /* LAPL ID for API operation */
     H5P_genplist_t *lapl;       /* Link Access Property List */
@@ -278,6 +282,12 @@ typedef struct H5CX_t {
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 #endif /* H5_HAVE_PARALLEL */
 
+    /* Cached LCPL properties */
+    H5T_cset_t encoding;     /* Link name character encoding */
+    hbool_t encoding_valid;  /* Whether link name character encoding is valid */
+    unsigned intermediate_group;       /* Whether to create intermediate groups */
+    hbool_t intermediate_group_valid;  /* Whether create intermediate group flag is valid */
+
     /* Cached LAPL properties */
     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 */
@@ -285,6 +295,8 @@ typedef struct H5CX_t {
     /* Cached DCPL properties */
     hbool_t   do_min_dset_ohdr;   /* Whether to minimize dataset object header */
     hbool_t   do_min_dset_ohdr_valid;   /* Whether minimize dataset object header flag is valid */
+    uint8_t ohdr_flags;  /* Object header flags */
+    hbool_t ohdr_flags_valid;  /* Whether the object headers flags are valid */
 
     /* Cached DAPL properties */
     const char *extfile_prefix;         /* Prefix for external file                      */
@@ -346,6 +358,13 @@ typedef struct H5CX_dxpl_cache_t {
     H5T_conv_cb_t dt_conv_cb;       /* Datatype conversion struct (H5D_XFER_CONV_CB_NAME) */
 } H5CX_dxpl_cache_t;
 
+/* Typedef for cached default link creation property list information */
+/* (Same as the cached DXPL struct, above, except for the default LCPL) */
+typedef struct H5CX_lcpl_cache_t {
+    H5T_cset_t encoding;         /* Link name character encoding */
+    unsigned intermediate_group; /* Whether to create intermediate groups  */
+} H5CX_lcpl_cache_t;
+
 /* Typedef for cached default link access property list information */
 /* (Same as the cached DXPL struct, above, except for the default LAPL) */
 typedef struct H5CX_lapl_cache_t {
@@ -356,6 +375,7 @@ typedef struct H5CX_lapl_cache_t {
 /* (Same as the cached DXPL struct, above, except for the default DCPL) */
 typedef struct H5CX_dcpl_cache_t {
     hbool_t do_min_dset_ohdr;   /* Whether to minimize dataset object header */
+    uint8_t ohdr_flags;  /* Object header flags */
 } H5CX_dcpl_cache_t;
 
 /* Typedef for cached default dataset access property list information */
@@ -401,6 +421,9 @@ static H5CX_node_t *H5CX_head_g = NULL;         /* Pointer to head of context st
 /* Define a "default" dataset transfer property list cache structure to use for default DXPLs */
 static H5CX_dxpl_cache_t H5CX_def_dxpl_cache;
 
+/* Define a "default" link creation property list cache structure to use for default LCPLs */
+static H5CX_lcpl_cache_t H5CX_def_lcpl_cache;
+
 /* Define a "default" link access property list cache structure to use for default LAPLs */
 static H5CX_lapl_cache_t H5CX_def_lapl_cache;
 
@@ -435,6 +458,7 @@ herr_t
 H5CX__init_package(void)
 {
     H5P_genplist_t *dx_plist;           /* Data transfer property list */
+    H5P_genplist_t *lc_plist;           /* Link creation property list */
     H5P_genplist_t *la_plist;           /* Link access property list */
     H5P_genplist_t *dc_plist;           /* Dataset creation property list */
     H5P_genplist_t *da_plist;           /* Dataset access property list */
@@ -525,6 +549,23 @@ H5CX__init_package(void)
     if(H5P_get(dx_plist, H5D_XFER_CONV_CB_NAME, &H5CX_def_dxpl_cache.dt_conv_cb) < 0)
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve datatype conversion exception callback")
 
+    /* Reset the "default LCPL cache" information */
+    HDmemset(&H5CX_def_lcpl_cache, 0, sizeof(H5CX_lcpl_cache_t));
+
+    /* Get the default LCPL cache information */
+
+    /* Get the default link creation property list */
+    if(NULL == (lc_plist = (H5P_genplist_t *)H5I_object(H5P_LINK_CREATE_DEFAULT)))
+        HGOTO_ERROR(H5E_CONTEXT, H5E_BADTYPE, FAIL, "not a link creation property list")
+
+    /* Get link name character encoding */
+    if(H5P_get(lc_plist, H5P_STRCRT_CHAR_ENCODING_NAME, &H5CX_def_lcpl_cache.encoding) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve link name encoding")
+
+    /* Get flag whether to create intermediate groups */
+    if(H5P_get(lc_plist, H5L_CRT_INTERMEDIATE_GROUP_NAME, &H5CX_def_lcpl_cache.intermediate_group) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve intermediate group creation flag")
+
     /* Reset the "default LAPL cache" information */
     HDmemset(&H5CX_def_lapl_cache, 0, sizeof(H5CX_lapl_cache_t));
 
@@ -552,6 +593,10 @@ H5CX__init_package(void)
     if(H5P_get(dc_plist, H5D_CRT_MIN_DSET_HDR_SIZE_NAME, &H5CX_def_dcpl_cache.do_min_dset_ohdr) < 0)
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve dataset minimize flag")
 
+    /* Get object header flags */
+    if(H5P_get(dc_plist, H5O_CRT_OHDR_FLAGS_NAME, &H5CX_def_dcpl_cache.ohdr_flags) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve object header flags")
+
     /* Reset the "default DAPL cache" information */
     HDmemset(&H5CX_def_dapl_cache, 0, sizeof(H5CX_dapl_cache_t));
 
@@ -710,6 +755,7 @@ H5CX__push_common(H5CX_node_t *cnode)
     cnode->ctx.dxpl_id = H5P_DATASET_XFER_DEFAULT;
     cnode->ctx.dcpl_id = H5P_DATASET_CREATE_DEFAULT;
     cnode->ctx.dapl_id = H5P_DATASET_ACCESS_DEFAULT;
+    cnode->ctx.lcpl_id = H5P_LINK_CREATE_DEFAULT;
     cnode->ctx.lapl_id = H5P_LINK_ACCESS_DEFAULT;
     cnode->ctx.fapl_id = H5P_FILE_ACCESS_DEFAULT;
     cnode->ctx.tag = H5AC__INVALID_TAG;
@@ -820,6 +866,18 @@ H5CX_retrieve_state(H5CX_state_t **api_state)
     if(NULL == (*api_state = H5FL_CALLOC(H5CX_state_t)))
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTALLOC, FAIL, "unable to allocate new API context state")
 
+    /* Check for non-default DCPL */
+    if(H5P_DATASET_CREATE_DEFAULT != (*head)->ctx.dcpl_id) {
+        /* Retrieve the DCPL property list */
+        H5CX_RETRIEVE_PLIST(dcpl, FAIL)
+
+        /* Copy the DCPL ID */
+        if(((*api_state)->dcpl_id = H5P_copy_plist((H5P_genplist_t *)(*head)->ctx.dcpl, FALSE)) < 0)
+            HGOTO_ERROR(H5E_CONTEXT, H5E_CANTCOPY, FAIL, "can't copy property list")
+    } /* end if */
+    else
+        (*api_state)->dcpl_id = H5P_DATASET_CREATE_DEFAULT;
+
     /* Check for non-default DXPL */
     if(H5P_DATASET_XFER_DEFAULT != (*head)->ctx.dxpl_id) {
         /* Retrieve the DXPL property list */
@@ -844,6 +902,18 @@ H5CX_retrieve_state(H5CX_state_t **api_state)
     else
         (*api_state)->lapl_id = H5P_LINK_ACCESS_DEFAULT;
 
+    /* Check for non-default LCPL */
+    if(H5P_LINK_CREATE_DEFAULT != (*head)->ctx.lcpl_id) {
+        /* Retrieve the LCPL property list */
+        H5CX_RETRIEVE_PLIST(lcpl, FAIL)
+
+        /* Copy the LCPL ID */
+        if(((*api_state)->lcpl_id = H5P_copy_plist((H5P_genplist_t *)(*head)->ctx.lcpl, FALSE)) < 0)
+            HGOTO_ERROR(H5E_CONTEXT, H5E_CANTCOPY, FAIL, "can't copy property list")
+    } /* end if */
+    else
+        (*api_state)->lcpl_id = H5P_LINK_CREATE_DEFAULT;
+
     /* Keep a reference to the current VOL wrapping context */
     (*api_state)->vol_wrap_ctx = (*head)->ctx.vol_wrap_ctx;
     if(NULL != (*api_state)->vol_wrap_ctx)
@@ -916,6 +986,10 @@ H5CX_restore_state(const H5CX_state_t *api_state)
     HDassert(head && *head);
     HDassert(api_state);
 
+    /* Restore the DCPL info */
+    (*head)->ctx.dcpl_id = api_state->dcpl_id;
+    (*head)->ctx.dcpl = NULL;
+
     /* Restore the DXPL info */
     (*head)->ctx.dxpl_id = api_state->dxpl_id;
     (*head)->ctx.dxpl = NULL;
@@ -924,6 +998,10 @@ H5CX_restore_state(const H5CX_state_t *api_state)
     (*head)->ctx.lapl_id = api_state->lapl_id;
     (*head)->ctx.lapl = NULL;
 
+    /* Restore the LCPL info */
+    (*head)->ctx.lcpl_id = api_state->lcpl_id;
+    (*head)->ctx.lcpl = NULL;
+
     /* Restore the VOL wrapper context */
     (*head)->ctx.vol_wrap_ctx = api_state->vol_wrap_ctx;
 
@@ -964,6 +1042,11 @@ H5CX_free_state(H5CX_state_t *api_state)
     /* Sanity check */
     HDassert(api_state);
 
+    /* Release the DCPL */
+    if(api_state->dcpl_id != H5P_DATASET_CREATE_DEFAULT)
+        if(H5I_dec_ref(api_state->dcpl_id) < 0)
+            HGOTO_ERROR(H5E_CONTEXT, H5E_CANTDEC, FAIL, "can't decrement refcount on DCPL")
+
     /* Release the DXPL */
     if(api_state->dxpl_id != H5P_DATASET_XFER_DEFAULT)
         if(H5I_dec_ref(api_state->dxpl_id) < 0)
@@ -974,6 +1057,11 @@ H5CX_free_state(H5CX_state_t *api_state)
         if(H5I_dec_ref(api_state->lapl_id) < 0)
             HGOTO_ERROR(H5E_CONTEXT, H5E_CANTDEC, FAIL, "can't decrement refcount on LAPL")
 
+    /* Release the LCPL */
+    if(api_state->lcpl_id != H5P_LINK_CREATE_DEFAULT)
+        if(H5I_dec_ref(api_state->lcpl_id) < 0)
+            HGOTO_ERROR(H5E_CONTEXT, H5E_CANTDEC, FAIL, "can't decrement refcount on LCPL")
+
     /* Release the VOL wrapper context */
     if(api_state->vol_wrap_ctx)
         if(H5VL_dec_vol_wrapper(api_state->vol_wrap_ctx) < 0)
@@ -1119,6 +1207,35 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_set_lcpl
+ *
+ * Purpose:     Sets the LCPL for the current API call context.
+ *
+ * Return:      <none>
+ *
+ * Programmer:  Chris Hogan
+ *              October 28, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+void
+H5CX_set_lcpl(hid_t lcpl_id)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Sanity check */
+    HDassert(*head);
+
+    /* Set the API context's LCPL to a new value */
+    (*head)->ctx.lcpl_id = lcpl_id;
+
+    FUNC_LEAVE_NOAPI_VOID
+} /* end H5CX_set_lcpl() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX_set_lapl
  *
  * Purpose:     Sets the LAPL for the current API call context.
@@ -2371,6 +2488,76 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_get_encoding
+ *
+ * Purpose:     Retrieves the character encoding for the current API call context.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Gerd Heber
+ *              October 21, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_encoding(H5T_cset_t* encoding)
+{
+    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(encoding);
+    HDassert(head && *head);
+    HDassert(H5P_DEFAULT != (*head)->ctx.lcpl_id);
+
+    H5CX_RETRIEVE_PROP_VALID(lcpl, H5P_LINK_CREATE_DEFAULT, H5P_STRCRT_CHAR_ENCODING_NAME, encoding)
+
+    /* Get the value */
+    *encoding = (*head)->ctx.encoding;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_encoding() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_get_intermediate_group
+ *
+ * Purpose:     Retrieves the create intermediate group flag for the current API call context.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Gerd Heber
+ *              October 21, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_intermediate_group(unsigned* crt_intermed_group)
+{
+    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(crt_intermed_group);
+    HDassert(head && *head);
+    HDassert(H5P_DEFAULT != (*head)->ctx.lcpl_id);
+
+    H5CX_RETRIEVE_PROP_VALID(lcpl, H5P_LINK_CREATE_DEFAULT, H5L_CRT_INTERMEDIATE_GROUP_NAME, intermediate_group)
+
+    /* Get the value */
+    *crt_intermed_group = (*head)->ctx.intermediate_group;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_create_intermediate_group() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX_get_nlinks
  *
  * Purpose:     Retrieves the # of soft / UD links to traverse for the current API call context.
@@ -3284,6 +3471,41 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_get_ohdr_flags
+ *
+ * Purpose:     Retrieves the object header flags for the current API call context.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Chris Hogan
+ *              November 15, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_ohdr_flags(uint8_t *ohdr_flags)
+{
+    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(ohdr_flags);
+    HDassert(head && *head);
+    HDassert(H5P_DEFAULT != (*head)->ctx.dcpl_id);
+
+    H5CX_RETRIEVE_PROP_VALID(dcpl, H5P_DATASET_CREATE_DEFAULT, H5O_CRT_OHDR_FLAGS_NAME, ohdr_flags)
+
+    /* Get the value */
+    *ohdr_flags = (*head)->ctx.ohdr_flags;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* End H5CX_get_ohdr_flags() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX__pop_common
  *
  * Purpose:     Common code for popping the context for an API call.
diff --git a/src/H5CXprivate.h b/src/H5CXprivate.h
index 2f86adf..2ae71f3 100644
--- a/src/H5CXprivate.h
+++ b/src/H5CXprivate.h
@@ -41,8 +41,10 @@
 
 /* API context state */
 typedef struct H5CX_state_t {
+    hid_t dcpl_id;              /* DCPL for operation */
     hid_t dxpl_id;              /* DXPL for operation */
     hid_t lapl_id;              /* LAPL for operation */
+    hid_t lcpl_id;              /* LCPL for operation */
     void *vol_wrap_ctx;         /* VOL connector's "wrap context" for creating IDs */
     H5VL_connector_prop_t vol_connector_prop;   /* VOL connector property */
 
@@ -77,6 +79,7 @@ H5_DLL herr_t H5CX_free_state(H5CX_state_t *api_state);
 
 /* "Setter" routines for API context info */
 H5_DLL void H5CX_set_dxpl(hid_t dxpl_id);
+H5_DLL void H5CX_set_lcpl(hid_t lcpl_id);
 H5_DLL void H5CX_set_lapl(hid_t lapl_id);
 H5_DLL void H5CX_set_dcpl(hid_t dcpl_id);
 H5_DLL herr_t H5CX_set_libver_bounds(H5F_t *f);
@@ -122,11 +125,16 @@ H5_DLL herr_t H5CX_get_data_transform(H5Z_data_xform_t **data_transform);
 H5_DLL herr_t H5CX_get_vlen_alloc_info(H5T_vlen_alloc_info_t *vl_alloc_info);
 H5_DLL herr_t H5CX_get_dt_conv_cb(H5T_conv_cb_t *cb_struct);
 
+/* "Getter" routines for LCPL properties cached in API context */
+H5_DLL herr_t H5CX_get_encoding(H5T_cset_t* encoding);
+H5_DLL herr_t H5CX_get_intermediate_group(unsigned* crt_intermed_group);
+
 /* "Getter" routines for LAPL properties cached in API context */
 H5_DLL herr_t H5CX_get_nlinks(size_t *nlinks);
 
 /* "Getter" routines for DCPL properties cached in API context */
 H5_DLL herr_t H5CX_get_dset_min_ohdr_flag(hbool_t *dset_min_ohdr_flag);
+H5_DLL herr_t H5CX_get_ohdr_flags(uint8_t *ohdr_flags);
 
 /* "Getter" routines for DAPL properties cached in API context */
 H5_DLL herr_t H5CX_get_ext_file_prefix(const char **prefix_extfile);
diff --git a/src/H5D.c b/src/H5D.c
index 9d811c6..a2e6f0a 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -137,6 +137,9 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     /* Set the DCPL for the API context */
     H5CX_set_dcpl(dcpl_id);
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&dapl_id, H5P_CLS_DACC, loc_id, TRUE) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
diff --git a/src/H5Dvirtual.c b/src/H5Dvirtual.c
index 53640e7..877aadb 100644
--- a/src/H5Dvirtual.c
+++ b/src/H5Dvirtual.c
@@ -2406,7 +2406,7 @@ H5D__virtual_pre_io(H5D_io_info_t *io_info,
                         /* Project intersection of virtual space and clipped
                          * virtual space onto source space (create
                          * clipped_source_select) */
-                        if(H5S_select_project_intersection(storage->list[i].sub_dset[j].virtual_select, storage->list[i].source_select, storage->list[i].sub_dset[j].clipped_virtual_select, &storage->list[i].sub_dset[j].clipped_source_select) < 0)
+                        if(H5S_select_project_intersection(storage->list[i].sub_dset[j].virtual_select, storage->list[i].source_select, storage->list[i].sub_dset[j].clipped_virtual_select, &storage->list[i].sub_dset[j].clipped_source_select, TRUE) < 0)
                             HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto memory space")
 
                         /* Set extents of virtual_select and
@@ -2423,7 +2423,7 @@ H5D__virtual_pre_io(H5D_io_info_t *io_info,
                 if(storage->list[i].sub_dset[j].clipped_virtual_select) {
                     /* Project intersection of file space and mapping virtual space
                      * onto memory space */
-                    if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].sub_dset[j].clipped_virtual_select, &storage->list[i].sub_dset[j].projected_mem_space) < 0)
+                    if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].sub_dset[j].clipped_virtual_select, &storage->list[i].sub_dset[j].projected_mem_space, TRUE) < 0)
                         HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto memory space")
 
                     /* Check number of elements selected */
@@ -2460,7 +2460,7 @@ H5D__virtual_pre_io(H5D_io_info_t *io_info,
             if(storage->list[i].source_dset.clipped_virtual_select) {
                 /* Project intersection of file space and mapping virtual space onto
                  * memory space */
-                if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].source_dset.clipped_virtual_select, &storage->list[i].source_dset.projected_mem_space) < 0)
+                if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].source_dset.clipped_virtual_select, &storage->list[i].source_dset.projected_mem_space, TRUE) < 0)
                     HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto memory space")
 
                 /* Check number of elements selected, add to tot_nelmts */
@@ -2590,7 +2590,7 @@ H5D__virtual_read_one(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
 
         /* Project intersection of file space and mapping virtual space onto
          * mapping source space */
-        if(H5S_select_project_intersection(source_dset->clipped_virtual_select, source_dset->clipped_source_select, file_space, &projected_src_space) < 0)
+        if(H5S_select_project_intersection(source_dset->clipped_virtual_select, source_dset->clipped_source_select, file_space, &projected_src_space, TRUE) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto source space")
 
         /* Perform read on source dataset */
@@ -2781,7 +2781,7 @@ H5D__virtual_write_one(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
          * extent in the unlimited dimension.  -NAF */
         /* Project intersection of file space and mapping virtual space onto
          * mapping source space */
-        if(H5S_select_project_intersection(source_dset->virtual_select, source_dset->clipped_source_select, file_space, &projected_src_space) < 0)
+        if(H5S_select_project_intersection(source_dset->virtual_select, source_dset->clipped_source_select, file_space, &projected_src_space, TRUE) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto source space")
 
         /* Perform write on source dataset */
diff --git a/src/H5G.c b/src/H5G.c
index fdf613c..85515d3 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -345,6 +345,9 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id,
         if(TRUE != H5P_isa_class(gcpl_id, H5P_GROUP_CREATE))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a group creation property list")
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&gapl_id, H5P_CLS_GACC, loc_id, TRUE) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
diff --git a/src/H5L.c b/src/H5L.c
index 1e554a9..c8c8cde 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -299,6 +299,9 @@ H5Lmove(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&lapl_id, H5P_CLS_LACC, 
             ((src_loc_id != H5L_SAME_LOC) ? src_loc_id : dst_loc_id), TRUE) < 0)
@@ -386,6 +389,9 @@ H5Lcopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&lapl_id, H5P_CLS_LACC, 
             ((src_loc_id != H5L_SAME_LOC) ? src_loc_id : dst_loc_id), TRUE) < 0)
@@ -473,10 +479,13 @@ H5Lcreate_soft(const char *link_target, hid_t link_loc_id, const char *link_name
     if(lcpl_id != H5P_DEFAULT && (TRUE != H5P_isa_class(lcpl_id, H5P_LINK_CREATE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a link creation property list")
 
-    /* Check the group access property list */
+    /* Get the link creation property list */
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Set location fields */
     loc_params.type                         = H5VL_OBJECT_BY_NAME;
     loc_params.loc_data.loc_by_name.name    = link_name;
@@ -549,6 +558,9 @@ H5Lcreate_hard(hid_t cur_loc_id, const char *cur_name,
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&lapl_id, H5P_CLS_LACC, cur_loc_id, TRUE) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTSET, FAIL, "can't set access property list info")
@@ -635,10 +647,13 @@ H5Lcreate_ud(hid_t link_loc_id, const char *link_name, H5L_type_t link_type,
     if(!udata && udata_size)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "udata cannot be NULL if udata_size is non-zero")
 
-    /* Check the group access property list */
+    /* Get the link creation property list */
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&lapl_id, H5P_CLS_LACC, link_loc_id, TRUE) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTSET, FAIL, "can't set access property list info")
@@ -1850,8 +1865,8 @@ H5L__link_cb(H5G_loc_t *grp_loc/*in*/, const char *name, const H5O_link_t H5_ATT
     /* Check for non-default link creation properties */
     if(udata->lc_plist) {
         /* Get character encoding property */
-        if(H5P_get(udata->lc_plist, H5P_STRCRT_CHAR_ENCODING_NAME, &udata->lnk->cset) < 0)
-            HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't get property value for character encoding")
+        if(H5CX_get_encoding(&udata->lnk->cset) < 0)
+            HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't get 'character set' property")
     } /* end if */
     else
         udata->lnk->cset = H5F_DEFAULT_CSET;   /* Default character encoding for link */
@@ -1992,8 +2007,8 @@ H5L__create_real(const H5G_loc_t *link_loc, const char *link_name,
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
 
         /* Get intermediate group creation property */
-        if(H5P_get(lc_plist, H5L_CRT_INTERMEDIATE_GROUP_NAME, &crt_intmd_group) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for creating missing groups")
+        if(H5CX_get_intermediate_group(&crt_intmd_group) < 0)
+            HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't get 'create intermediate group' property")
 
         if(crt_intmd_group > 0)
             target_flags |= H5G_CRT_INTMD_GROUP;
@@ -2881,7 +2896,7 @@ H5L_move(const H5G_loc_t *src_loc, const char *src_name, const H5G_loc_t *dst_lo
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
 
         /* Get intermediate group creation property */
-        if(H5P_get(lc_plist, H5L_CRT_INTERMEDIATE_GROUP_NAME, &crt_intmd_group) < 0)
+        if(H5CX_get_intermediate_group(&crt_intmd_group) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for creating missing groups")
 
         /* Set target flags for source and destination */
@@ -2889,7 +2904,7 @@ H5L_move(const H5G_loc_t *src_loc, const char *src_name, const H5G_loc_t *dst_lo
             dst_target_flags |= H5G_CRT_INTMD_GROUP;
 
         /* Get character encoding property */
-        if(H5P_get(lc_plist, H5P_STRCRT_CHAR_ENCODING_NAME, &char_encoding) < 0)
+        if(H5CX_get_encoding(&char_encoding) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for character encoding")
     } /* end if */
 
diff --git a/src/H5Lexternal.c b/src/H5Lexternal.c
index 3c4ffcc..e075ed7 100644
--- a/src/H5Lexternal.c
+++ b/src/H5Lexternal.c
@@ -364,10 +364,13 @@ H5Lcreate_external(const char *file_name, const char *obj_name,
     if(!link_name || !*link_name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no link name specified")
 
-    /* Check the group access property list */
+    /* Get the link creation property list */
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Get normalized copy of the link target */
     if(NULL == (norm_obj_name = H5G_normalize(obj_name)))
         HGOTO_ERROR(H5E_LINK, H5E_BADVALUE, FAIL, "can't normalize object name")
diff --git a/src/H5O.c b/src/H5O.c
index ffb49d9..b79914c 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -360,10 +360,13 @@ H5Olink(hid_t obj_id, hid_t new_loc_id, const char *new_name, hid_t lcpl_id,
     if(lcpl_id != H5P_DEFAULT && (TRUE != H5P_isa_class(lcpl_id, H5P_LINK_CREATE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a link creation property list")
 
-    /* Check the group access property list */
+    /* Get the link creation property list */
     if(H5P_DEFAULT == lcpl_id)
         lcpl_id = H5P_LINK_CREATE_DEFAULT;
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&lapl_id, H5P_CLS_LACC, obj_id, TRUE) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set access property list info")
diff --git a/src/H5Ocopy.c b/src/H5Ocopy.c
index 6e0db25..55013c9 100644
--- a/src/H5Ocopy.c
+++ b/src/H5Ocopy.c
@@ -227,6 +227,9 @@ H5Ocopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
         if(TRUE != H5P_isa_class(ocpypl_id, H5P_OBJECT_COPY))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not object copy property list")
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Set up collective metadata if appropriate */
     if(H5CX_set_loc(src_loc_id) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set collective metadata read info")
diff --git a/src/H5Oint.c b/src/H5Oint.c
index ecf347c..b97ff30 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -352,8 +352,18 @@ H5O__create_ohdr(H5F_t *f, hid_t ocpl_id)
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, NULL, "not a property list")
 
     /* Get any object header status flags set by properties */
-    if(H5P_get(oc_plist, H5O_CRT_OHDR_FLAGS_NAME, &oh_flags) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get object header flags")
+    if(H5P_DATASET_CREATE_DEFAULT == ocpl_id)
+    {
+        /* If the OCPL is the default DCPL, we can get the header flags from the
+         * API context. Otherwise we have to call H5P_get */
+        if(H5CX_get_ohdr_flags(&oh_flags) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get object header flags")
+    }
+    else
+    {
+        if(H5P_get(oc_plist, H5O_CRT_OHDR_FLAGS_NAME, &oh_flags) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get object header flags")
+    }
 
     if(H5O_set_version(f, oh, oh_flags, H5F_STORE_MSG_CRT_IDX(f)) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, NULL, "can't set version of object header")
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index cd702e0..2c7502a 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -96,6 +96,7 @@ typedef struct {
     hsize_t skip;           /* Number of elements to skip in projected space */
     hsize_t nelem;          /* Number of elements to add to projected space (after skip) */
     uint64_t op_gen;        /* Operation generation for counting elements */
+    hbool_t share_selection; /* Whether span trees in dst_space can be shared with proj_space */
 } H5S_hyper_project_intersect_ud_t;
 
 /* Assert that H5S_MAX_RANK is <= 32 so our trick with using a 32 bit bitmap
@@ -112,6 +113,9 @@ typedef struct {
 static H5S_hyper_span_t *H5S__hyper_new_span(hsize_t low, hsize_t high,
     H5S_hyper_span_info_t *down, H5S_hyper_span_t *next);
 static H5S_hyper_span_info_t *H5S__hyper_new_span_info(unsigned rank);
+static H5S_hyper_span_info_t *H5S__hyper_copy_span_helper(
+    H5S_hyper_span_info_t *spans, unsigned rank, unsigned op_info_i,
+    uint64_t op_gen);
 static H5S_hyper_span_info_t *H5S__hyper_copy_span(H5S_hyper_span_info_t *spans,
     unsigned rank);
 static hbool_t H5S__hyper_cmp_spans(const H5S_hyper_span_info_t *span_info1,
@@ -132,7 +136,7 @@ static herr_t H5S__hyper_clip_spans(H5S_hyper_span_info_t *a_spans,
     H5S_hyper_span_info_t **a_and_b, H5S_hyper_span_info_t **b_not_a);
 static herr_t H5S__hyper_merge_spans(H5S_t *space, H5S_hyper_span_info_t *new_spans);
 static hsize_t H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans,
-    uint64_t op_gen);
+    unsigned op_info_i, uint64_t op_gen);
 static hsize_t H5S__hyper_spans_nelem(H5S_hyper_span_info_t *spans);
 static herr_t H5S__hyper_add_disjoint_spans(H5S_t *space, H5S_hyper_span_info_t *new_spans);
 static H5S_hyper_span_info_t *H5S__hyper_make_spans(unsigned rank,
@@ -2852,9 +2856,10 @@ done:
  PURPOSE
     Helper routine to copy a hyperslab span tree
  USAGE
-    H5S_hyper_span_info_t * H5S__hyper_copy_span_helper(spans, rank)
+    H5S_hyper_span_info_t * H5S__hyper_copy_span_helper(spans, rank, op_info_i, op_gen)
         H5S_hyper_span_info_t *spans;   IN: Span tree to copy
         unsigned rank;                  IN: Rank of span tree
+        unsigned op_info_i;             IN: Index of op info to use
         uint64_t op_gen;                IN: Operation generation
  RETURNS
     Pointer to the copied span tree on success, NULL on failure
@@ -2867,7 +2872,7 @@ done:
 --------------------------------------------------------------------------*/
 static H5S_hyper_span_info_t *
 H5S__hyper_copy_span_helper(H5S_hyper_span_info_t *spans, unsigned rank,
-    uint64_t op_gen)
+    unsigned op_info_i, uint64_t op_gen)
 {
     H5S_hyper_span_t *span;         /* Hyperslab span */
     H5S_hyper_span_t *new_span;     /* Temporary hyperslab span */
@@ -2881,9 +2886,9 @@ H5S__hyper_copy_span_helper(H5S_hyper_span_info_t *spans, unsigned rank,
     HDassert(spans);
 
     /* Check if the span tree was already copied */
-    if(spans->op_gen == op_gen) {
+    if(spans->op_info[op_info_i].op_gen == op_gen) {
         /* Just return the value of the already copied span tree */
-        ret_value = spans->u.copied;
+        ret_value = spans->op_info[op_info_i].u.copied;
 
         /* Increment the reference count of the span tree */
         ret_value->count++;
@@ -2899,10 +2904,10 @@ H5S__hyper_copy_span_helper(H5S_hyper_span_info_t *spans, unsigned rank,
         ret_value->count = 1;
 
         /* Set the operation generation for the span info, to avoid future copies */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
 
         /* Set the 'copied' pointer in the node being copied to the newly allocated node */
-        spans->u.copied = ret_value;
+        spans->op_info[op_info_i].u.copied = ret_value;
 
         /* Copy over the nodes in the span list */
         span = spans->head;
@@ -2920,7 +2925,7 @@ H5S__hyper_copy_span_helper(H5S_hyper_span_info_t *spans, unsigned rank,
 
             /* Recurse to copy the 'down' spans, if there are any */
             if(span->down != NULL) {
-                if(NULL == (new_down = H5S__hyper_copy_span_helper(span->down, rank - 1, op_gen)))
+                if(NULL == (new_down = H5S__hyper_copy_span_helper(span->down, rank - 1, op_info_i, op_gen)))
                     HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy hyperslab spans")
                 new_span->down = new_down;
             } /* end if */
@@ -2976,7 +2981,9 @@ H5S__hyper_copy_span(H5S_hyper_span_info_t *spans, unsigned rank)
     op_gen = H5S__hyper_get_op_gen();
 
     /* Copy the hyperslab span tree */
-    if(NULL == (ret_value = H5S__hyper_copy_span_helper(spans, rank, op_gen)))
+    /* Always use op_info[0] since we own this op_info, so there can be no
+     * simultaneous operations */
+    if(NULL == (ret_value = H5S__hyper_copy_span_helper(spans, rank, 0, op_gen)))
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy hyperslab span tree")
 
 done:
@@ -3315,8 +3322,9 @@ done:
  PURPOSE
     Helper routine to count the number of blocks in a span tree
  USAGE
-    hsize_t H5S__hyper_span_nblocks_helper(spans)
+    hsize_t H5S__hyper_span_nblocks_helper(spans, op_info_i, op_gen)
         H5S_hyper_span_info_t *spans; IN: Hyperslab span tree to count blocks of
+        unsigned op_info_i; IN: Index of op info to use
         uint64_t op_gen;   IN: Operation generation
  RETURNS
     Number of blocks in span tree on success; negative on failure
@@ -3328,7 +3336,8 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 static hsize_t
-H5S__hyper_span_nblocks_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
+H5S__hyper_span_nblocks_helper(H5S_hyper_span_info_t *spans, unsigned op_info_i,
+    uint64_t op_gen)
 {
     hsize_t ret_value = 0;      /* Return value */
 
@@ -3338,9 +3347,9 @@ H5S__hyper_span_nblocks_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
     HDassert(spans);
 
     /* Check if the span tree was already counted */
-    if(spans->op_gen == op_gen)
+    if(spans->op_info[op_info_i].op_gen == op_gen)
         /* Just return the # of blocks in the already counted span tree */
-        ret_value = spans->u.nblocks;
+        ret_value = spans->op_info[op_info_i].u.nblocks;
     else {      /* Count the number of elements in the span tree */
         H5S_hyper_span_t *span;     /* Hyperslab span */
 
@@ -3348,7 +3357,7 @@ H5S__hyper_span_nblocks_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
         if(span->down) {
             while(span) {
                 /* If there are down spans, add the total down span blocks */
-                ret_value += H5S__hyper_span_nblocks_helper(span->down, op_gen);
+                ret_value += H5S__hyper_span_nblocks_helper(span->down, op_info_i, op_gen);
 
                 /* Advance to next span */
                 span = span->next;
@@ -3365,10 +3374,10 @@ H5S__hyper_span_nblocks_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
         } /* end else */
 
         /* Set the operation generation for this span tree, to avoid re-computing */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
 
         /* Hold a copy of the # of blocks */
-        spans->u.nblocks = ret_value;
+        spans->op_info[op_info_i].u.nblocks = ret_value;
     } /* end else */
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -3406,7 +3415,10 @@ H5S__hyper_span_nblocks(H5S_hyper_span_info_t *spans)
         /* Acquire an operation generation value for this operation */
         op_gen = H5S__hyper_get_op_gen();
 
-        ret_value = H5S__hyper_span_nblocks_helper(spans, op_gen);
+        /* Count the blocks */
+        /* Always use op_info[0] since we own this op_info, so there can be no
+         * simultaneous operations */
+        ret_value = H5S__hyper_span_nblocks_helper(spans, 0, op_gen);
     } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -5946,7 +5958,7 @@ H5S__hyper_add_span_element_helper(H5S_hyper_span_info_t *span_tree,
                     /* Check if we've compared the 'stop' span's "down tree" to
                      *      this span's "down tree" already.
                      */
-                    if(tmp_span->down->op_gen != op_gen) {
+                    if(tmp_span->down->op_info[0].op_gen != op_gen) {
                         if(H5S__hyper_cmp_spans(tmp_span->down, stop_span->down))
                             attempt_merge_spans = TRUE;
 
@@ -5954,7 +5966,7 @@ H5S__hyper_add_span_element_helper(H5S_hyper_span_info_t *span_tree,
                         /* (Because it wasn't the same as the 'stop' span's down tree
                          *      and we don't need to compare it again)
                          */
-                        tmp_span->down->op_gen = op_gen;
+                        tmp_span->down->op_info[0].op_gen = op_gen;
                     } /* end if */
                 } /* end else */
 
@@ -6159,11 +6171,12 @@ done:
  PURPOSE
     Helper routine to detect intersections in span trees
  USAGE
-    hbool_t H5S__hyper_intersect_block_helper(spans, start, end)
+    hbool_t H5S__hyper_intersect_block_helper(spans, rank, start, end, op_info_i, op_gen)
         H5S_hyper_span_info_t *spans;     IN: First span tree to operate with
         unsigned rank;     IN: Number of dimensions for span tree
         hsize_t *start;    IN: Starting coordinate for block
         hsize_t *end;      IN: Ending coordinate for block
+        unsigned op_info_i;             IN: Index of op info to use
         uint64_t op_gen;   IN: Operation generation
  RETURN
     Non-negative (TRUE/FALSE) on success, can't fail
@@ -6176,7 +6189,8 @@ done:
 --------------------------------------------------------------------------*/
 static hbool_t
 H5S__hyper_intersect_block_helper(H5S_hyper_span_info_t *spans,
-    unsigned rank, const hsize_t *start, const hsize_t *end, uint64_t op_gen)
+    unsigned rank, const hsize_t *start, const hsize_t *end, unsigned op_info_i,
+    uint64_t op_gen)
 {
     hbool_t ret_value = FALSE;      /* Return value */
 
@@ -6188,7 +6202,7 @@ H5S__hyper_intersect_block_helper(H5S_hyper_span_info_t *spans,
     HDassert(end);
 
     /* Check if we've already visited this span tree */
-    if(spans->op_gen != op_gen) {
+    if(spans->op_info[op_info_i].op_gen != op_gen) {
         H5S_hyper_span_t *curr;         /* Pointer to current span in 1st span tree */
         unsigned u;                     /* Local index variable */
 
@@ -6221,7 +6235,7 @@ H5S__hyper_intersect_block_helper(H5S_hyper_span_info_t *spans,
                     /* If there is an intersection in the "down" dimensions,
                      * the span trees overlap.
                      */
-                    if(H5S__hyper_intersect_block_helper(curr->down, rank - 1, start + 1, end + 1, op_gen))
+                    if(H5S__hyper_intersect_block_helper(curr->down, rank - 1, start + 1, end + 1, op_info_i, op_gen))
                         HGOTO_DONE(TRUE)
 
                     /* No intersection in down dimensions, advance to next span */
@@ -6231,7 +6245,7 @@ H5S__hyper_intersect_block_helper(H5S_hyper_span_info_t *spans,
         } /* end while */
 
         /* Set the tree's operation generation */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
     } /* end if */
 
     /* Fall through with 'FALSE' return value */
@@ -6363,7 +6377,9 @@ H5S__hyper_intersect_block(const H5S_t *space, const hsize_t *start, const hsize
         op_gen = H5S__hyper_get_op_gen();
 
         /* Perform the span-by-span intersection check */
-        ret_value = H5S__hyper_intersect_block_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, start, end, op_gen);
+        /* Always use op_info[0] since we own this op_info, so there can be no
+         * simultaneous operations */
+        ret_value = H5S__hyper_intersect_block_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, start, end, 0, op_gen);
     } /* end else */
 
 done:
@@ -6377,10 +6393,11 @@ done:
  PURPOSE
     Helper routine to adjust offsets in span trees
  USAGE
-    void H5S__hyper_adjust_u_helper(spans, offset)
+    void H5S__hyper_adjust_u_helper(spans, rank, offset, op_info_i, op_gen)
         H5S_hyper_span_info_t *spans;   IN: Span tree to operate with
         unsigned rank;                  IN: Number of dimensions for span tree
         const hsize_t *offset;          IN: Offset to subtract
+        unsigned op_info_i;             IN: Index of op info to use
         uint64_t op_gen;                IN: Operation generation
  RETURNS
     None
@@ -6393,7 +6410,7 @@ done:
 --------------------------------------------------------------------------*/
 static void
 H5S__hyper_adjust_u_helper(H5S_hyper_span_info_t *spans, unsigned rank,
-    const hsize_t *offset, uint64_t op_gen)
+    const hsize_t *offset, unsigned op_info_i, uint64_t op_gen)
 {
     FUNC_ENTER_STATIC_NOERR
 
@@ -6402,7 +6419,7 @@ H5S__hyper_adjust_u_helper(H5S_hyper_span_info_t *spans, unsigned rank,
     HDassert(offset);
 
     /* Check if we've already set this span tree */
-    if(spans->op_gen != op_gen) {
+    if(spans->op_info[op_info_i].op_gen != op_gen) {
         H5S_hyper_span_t *span;     /* Pointer to current span in span tree */
         unsigned u;                 /* Local index variable */
 
@@ -6423,14 +6440,14 @@ H5S__hyper_adjust_u_helper(H5S_hyper_span_info_t *spans, unsigned rank,
 
             /* Recursively adjust spans in next dimension down */
             if(span->down != NULL)
-                H5S__hyper_adjust_u_helper(span->down, rank - 1, offset + 1, op_gen);
+                H5S__hyper_adjust_u_helper(span->down, rank - 1, offset + 1, op_info_i, op_gen);
 
             /* Advance to next span in this dimension */
             span = span->next;
         } /* end while */
 
         /* Set the tree's operation generation */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
     } /* end if */
 
     FUNC_LEAVE_NOAPI_VOID
@@ -6487,7 +6504,10 @@ H5S__hyper_adjust_u(H5S_t *space, const hsize_t *offset)
         /* Acquire an operation generation value for this operation */
         op_gen = H5S__hyper_get_op_gen();
 
-        H5S__hyper_adjust_u_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, offset, op_gen);
+        /* Perform adjustment */
+        /* Always use op_info[0] since we own this op_info, so there can be no
+         * simultaneous operations */
+        H5S__hyper_adjust_u_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, offset, 0, op_gen);
     } /* end if */
 
     FUNC_LEAVE_NOAPI(SUCCEED)
@@ -6897,10 +6917,11 @@ done:
  PURPOSE
     Helper routine to adjust offsets in span trees
  USAGE
-    void H5S__hyper_adjust_s_helper(spans, offset)
+    void H5S__hyper_adjust_s_helper(spans, rank, offset, op_info_i, op_gen)
         H5S_hyper_span_info_t *spans;   IN: Span tree to operate with
         unsigned rank;                  IN: Number of dimensions for span tree
         const hssize_t *offset;         IN: Offset to subtract
+        unsigned op_info_i;             IN: Index of op info to use
         uint64_t op_gen;                IN: Operation generation
  RETURNS
     None
@@ -6913,7 +6934,7 @@ done:
 --------------------------------------------------------------------------*/
 static void
 H5S__hyper_adjust_s_helper(H5S_hyper_span_info_t *spans, unsigned rank,
-    const hssize_t *offset, uint64_t op_gen)
+    const hssize_t *offset, unsigned op_info_i, uint64_t op_gen)
 {
     FUNC_ENTER_STATIC_NOERR
 
@@ -6922,7 +6943,7 @@ H5S__hyper_adjust_s_helper(H5S_hyper_span_info_t *spans, unsigned rank,
     HDassert(offset);
 
     /* Check if we've already set this span tree */
-    if(spans->op_gen != op_gen) {
+    if(spans->op_info[op_info_i].op_gen != op_gen) {
         H5S_hyper_span_t *span;     /* Pointer to current span in span tree */
         unsigned u;                 /* Local index variable */
 
@@ -6943,14 +6964,14 @@ H5S__hyper_adjust_s_helper(H5S_hyper_span_info_t *spans, unsigned rank,
 
             /* Recursively adjust spans in next dimension down */
             if(span->down != NULL)
-                H5S__hyper_adjust_s_helper(span->down, rank - 1, offset + 1, op_gen);
+                H5S__hyper_adjust_s_helper(span->down, rank - 1, offset + 1, op_info_i, op_gen);
 
             /* Advance to next span in this dimension */
             span = span->next;
         } /* end while */
 
         /* Set the tree's operation generation */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
     } /* end if */
 
     FUNC_LEAVE_NOAPI_VOID
@@ -7018,7 +7039,10 @@ H5S_hyper_adjust_s(H5S_t *space, const hssize_t *offset)
             /* Acquire an operation generation value for this operation */
             op_gen = H5S__hyper_get_op_gen();
 
-            H5S__hyper_adjust_s_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, offset, op_gen);
+            /* Perform the adjustment */
+            /* Always use op_info[0] since we own this op_info, so there can be no
+             * simultaneous operations */
+            H5S__hyper_adjust_s_helper(space->select.sel_info.hslab->span_lst, space->extent.rank, offset, 0, op_gen);
         } /* end if */
     } /* end if */
 
@@ -8281,8 +8305,9 @@ done:
  PURPOSE
     Count the number of elements in a span tree
  USAGE
-    hsize_t H5S__hyper_spans_nelem_helper(spans, op_gen)
+    hsize_t H5S__hyper_spans_nelem_helper(spans, op_info_i, op_gen)
         const H5S_hyper_span_info_t *spans; IN: Hyperslan span tree to count elements of
+        unsigned op_info_i;             IN: Index of op info to use
         uint64_t op_gen;                IN: Operation generation
  RETURNS
     Number of elements in span tree on success; negative on failure
@@ -8294,7 +8319,8 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 static hsize_t
-H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
+H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans, unsigned op_info_i,
+    uint64_t op_gen)
 {
     hsize_t ret_value = 0;          /* Return value */
 
@@ -8304,9 +8330,9 @@ H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
     HDassert(spans);
 
     /* Check if the span tree was already counted */
-    if(spans->op_gen == op_gen)
+    if(spans->op_info[op_info_i].op_gen == op_gen)
         /* Just return the # of elements in the already counted span tree */
-        ret_value = spans->u.nelmts;
+        ret_value = spans->op_info[op_info_i].u.nelmts;
     else {      /* Count the number of elements in the span tree */
         const H5S_hyper_span_t *span;     /* Hyperslab span */
 
@@ -8328,7 +8354,7 @@ H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
                 nelmts = (span->high - span->low) + 1;
 
                 /* Multiply the size of this span by the total down span elements */
-                ret_value += nelmts * H5S__hyper_spans_nelem_helper(span->down, op_gen);
+                ret_value += nelmts * H5S__hyper_spans_nelem_helper(span->down, op_info_i, op_gen);
 
                 /* Advance to next span */
                 span = span->next;
@@ -8336,10 +8362,10 @@ H5S__hyper_spans_nelem_helper(H5S_hyper_span_info_t *spans, uint64_t op_gen)
         } /* end else */
 
         /* Set the operation generation for this span tree, to avoid re-computing */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
 
         /* Hold a copy of the # of elements */
-        spans->u.nelmts = ret_value;
+        spans->op_info[op_info_i].u.nelmts = ret_value;
     } /* end else */
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -8378,7 +8404,9 @@ H5S__hyper_spans_nelem(H5S_hyper_span_info_t *spans)
     op_gen = H5S__hyper_get_op_gen();
 
     /* Count the number of elements in the span tree */
-    ret_value = H5S__hyper_spans_nelem_helper(spans, op_gen);
+    /* Always use op_info[0] since we own this op_info, so there can be no
+     * simultaneous operations */
+    ret_value = H5S__hyper_spans_nelem_helper(spans, 0, op_gen);
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5S__hyper_spans_nelem() */
@@ -8808,10 +8836,8 @@ H5S__hyper_update_diminfo(H5S_t *space, H5S_seloper_t op,
     (It can be recovered with regular selection)
  USAGE
     herr_t H5S__hyper_rebuild_helper(space)
-        const H5S_hyper_span_t *span;   IN: Portion of span tree to check
-        H5S_hyper_dim_t span_slab[];    OUT: Rebuilt section of hyperslab description
-        unsigned rank;                  IN: Current dimension to work on
-        uint64_t op_gen;                IN: Operation generation
+        const H5S_hyper_span_t *spans;  IN: Portion of span tree to check
+        H5S_hyper_dim_t span_slab_info[]; OUT: Rebuilt section of hyperslab description
  RETURNS
     TRUE/FALSE for hyperslab selection rebuilt
  DESCRIPTION
@@ -10833,6 +10859,7 @@ done:
 --------------------------------------------------------------------------*/
 static herr_t
 H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
+    H5S_hyper_span_info_t *copied_span_info = NULL; /* Temporary span info pointer */
     herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_STATIC
@@ -10852,15 +10879,15 @@ H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
                     /* If we will run out of elements to skip in this span,
                      * advance to the first not fully skipped span and break
                      * out of this loop (start moving downwards) */
-                    if(udata->skip < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, udata->op_gen)
+                    if(udata->skip < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, 0, udata->op_gen)
                             * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1)) {
-                        udata->ds_low[udata->depth] += udata->skip / udata->ds_span[udata->depth]->down->u.nelmts;
-                        udata->skip %= udata->ds_span[udata->depth]->down->u.nelmts;
+                        udata->ds_low[udata->depth] += udata->skip / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
+                        udata->skip %= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
                         break;
                     } /* end if */
 
                     /* Skip over this entire span */
-                    udata->skip -= udata->ds_span[udata->depth]->down->u.nelmts
+                    udata->skip -= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts
                             * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1);
                 } /* end if */
             } /* end if */
@@ -10919,15 +10946,15 @@ H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
                     /* If we will run out of elements to skip in this span,
                      * advance to the first not fully skipped span and
                      * continue down */
-                    if(udata->skip < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, udata->op_gen)
+                    if(udata->skip < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, 0, udata->op_gen)
                             * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1)) {
-                        udata->ds_low[udata->depth] += udata->skip / udata->ds_span[udata->depth]->down->u.nelmts;
-                        udata->skip %= udata->ds_span[udata->depth]->down->u.nelmts;
+                        udata->ds_low[udata->depth] += udata->skip / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
+                        udata->skip %= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
                         break;
                     } /* end if */
 
                     /* Skip over this entire span */
-                    udata->skip -= udata->ds_span[udata->depth]->down->u.nelmts
+                    udata->skip -= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts
                             * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1);
 
                     /* Advance to next span */
@@ -10972,27 +10999,59 @@ H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
                  * any complete spans, advance to the first not fully added
                  * span, and break out of this loop (start moving downwards)
                  */
-                if(udata->nelem < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, udata->op_gen)
+                if(udata->nelem < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, 0, udata->op_gen)
                         * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1)) {
-                    if(udata->nelem >= udata->ds_span[udata->depth]->down->u.nelmts) {
-                        if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
-                                udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
-                                udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->u.nelmts) - 1,
-                                udata->ds_span[udata->depth]->down) < 0)
-                            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
-                        udata->ds_low[udata->depth] += udata->nelem / udata->ds_span[udata->depth]->down->u.nelmts;
-                        udata->nelem %= udata->ds_span[udata->depth]->down->u.nelmts;
+                    if(udata->nelem >= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) {
+                        if(udata->share_selection) {
+                            if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                                    udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                                    udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) - 1,
+                                    udata->ds_span[udata->depth]->down) < 0)
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                        } /* end if */
+                        else {
+                            /* If we're not sharing the destination space's
+                             * spans, we must copy it first (then release it
+                             * afterwards) */
+                            if(NULL == (copied_span_info = H5S__hyper_copy_span_helper(udata->ds_span[udata->depth]->down, udata->ds_rank - udata->depth, 1, udata->op_gen)))
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination spans")
+                            if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                                    udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                                    udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) - 1,
+                                    copied_span_info) < 0)
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                            H5S__hyper_free_span_info(copied_span_info);
+                            copied_span_info = NULL;
+                        } /* end else */
+                        udata->ds_low[udata->depth] += udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
+                        udata->nelem %= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
                     } /* end if */
                     break;
                 } /* end if */
 
                 /* Append span tree for entire span */
-                if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                if(udata->share_selection) {
+                    if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
                             udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
                             udata->ds_span[udata->depth]->high,
                             udata->ds_span[udata->depth]->down) < 0)
                         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
-                udata->nelem -= udata->ds_span[udata->depth]->down->u.nelmts
+                } /* end if */
+                else {
+                    /* If we're not sharing the destination space's
+                     * spans, we must copy it first (then release it
+                     * afterwards) */
+                    if(NULL == (copied_span_info = H5S__hyper_copy_span_helper(udata->ds_span[udata->depth]->down, udata->ds_rank - udata->depth, 1, udata->op_gen)))
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination spans")
+                    if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                            udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                            udata->ds_span[udata->depth]->high,
+                            copied_span_info) < 0)
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                    H5S__hyper_free_span_info(copied_span_info);
+                    copied_span_info = NULL;
+                } /* end else */
+                udata->nelem -= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts
                         * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1);
             } /* end if */
         } /* end if */
@@ -11063,27 +11122,59 @@ H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
                  * span and continue down
                  */
                 HDassert(udata->ds_low[udata->depth] <= udata->ds_span[udata->depth]->high);
-                if(udata->nelem < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, udata->op_gen)
+                if(udata->nelem < H5S__hyper_spans_nelem_helper(udata->ds_span[udata->depth]->down, 0, udata->op_gen)
                         * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1)) {
-                    if(udata->nelem >= udata->ds_span[udata->depth]->down->u.nelmts) {
-                        if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
-                                udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
-                                udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->u.nelmts) - 1,
-                                udata->ds_span[udata->depth]->down) < 0)
-                            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
-                        udata->ds_low[udata->depth] += udata->nelem / udata->ds_span[udata->depth]->down->u.nelmts;
-                        udata->nelem %= udata->ds_span[udata->depth]->down->u.nelmts;
+                    if(udata->nelem >= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) {
+                        if(udata->share_selection) {
+                            if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                                    udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                                    udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) - 1,
+                                    udata->ds_span[udata->depth]->down) < 0)
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                        } /* end if */
+                        else {
+                            /* If we're not sharing the destination space's
+                             * spans, we must copy it first (then release it
+                             * afterwards) */
+                            if(NULL == (copied_span_info = H5S__hyper_copy_span_helper(udata->ds_span[udata->depth]->down, udata->ds_rank - udata->depth, 1, udata->op_gen)))
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination spans")
+                            if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                                    udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                                    udata->ds_low[udata->depth] + (udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts) - 1,
+                                    copied_span_info) < 0)
+                                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                            H5S__hyper_free_span_info(copied_span_info);
+                            copied_span_info = NULL;
+                        } /* end else */
+                        udata->ds_low[udata->depth] += udata->nelem / udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
+                        udata->nelem %= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts;
                     } /* end if */
                     break;
                 } /* end if */
 
                 /* Append span tree for entire span */
-                if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                if(udata->share_selection) {
+                    if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
                             udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
                             udata->ds_span[udata->depth]->high,
                             udata->ds_span[udata->depth]->down) < 0)
                         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
-                udata->nelem -= udata->ds_span[udata->depth]->down->u.nelmts
+                } /* end if */
+                else {
+                    /* If we're not sharing the destination space's
+                     * spans, we must copy it first (then release it
+                     * afterwards) */
+                    if(NULL == (copied_span_info = H5S__hyper_copy_span_helper(udata->ds_span[udata->depth]->down, udata->ds_rank - udata->depth, 1, udata->op_gen)))
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination spans")
+                    if(H5S__hyper_append_span(&udata->ps_span_info[udata->depth],
+                            udata->ds_rank - udata->depth, udata->ds_low[udata->depth],
+                            udata->ds_span[udata->depth]->high,
+                            copied_span_info) < 0)
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTAPPEND, FAIL, "can't allocate hyperslab span")
+                    H5S__hyper_free_span_info(copied_span_info);
+                    copied_span_info = NULL;
+                } /* end else */
+                udata->nelem -= udata->ds_span[udata->depth]->down->op_info[0].u.nelmts
                         * (udata->ds_span[udata->depth]->high - udata->ds_low[udata->depth] + 1);
 
                 /* Advance to next span */
@@ -11128,6 +11219,13 @@ H5S__hyper_proj_int_build_proj(H5S_hyper_project_intersect_ud_t *udata) {
     udata->ps_clean_bitmap = 0;
 
 done:
+    /* Cleanup on failure */
+    if(copied_span_info) {
+        HDassert(ret_value < 0);
+        H5S__hyper_free_span_info(copied_span_info);
+        copied_span_info = NULL;
+    } /* end if */
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5S__hyper_proj_int_build_proj() */
 
@@ -11217,7 +11315,7 @@ H5S__hyper_proj_int_iterate(const H5S_hyper_span_info_t *ss_span_info,
                         /* Add skipped elements if there's a pre-gap */
                         if(ss_low < sis_low) {
                             low = sis_low;
-                            H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, udata->op_gen) * (sis_low - ss_low), FAIL);
+                            H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, 0, udata->op_gen) * (sis_low - ss_low), FAIL);
                         } /* end if */
                         else
                             low = ss_low;
@@ -11273,7 +11371,7 @@ H5S__hyper_proj_int_iterate(const H5S_hyper_span_info_t *ss_span_info,
                     if(ss_span->high < sis_low) {
                         /* Add skipped elements */
                         if(ss_span->down)
-                            H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, udata->op_gen) * (ss_span->high - ss_low + 1), FAIL);
+                            H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, 0, udata->op_gen) * (ss_span->high - ss_low + 1), FAIL);
                         else
                             H5S_HYPER_PROJ_INT_ADD_SKIP(udata, ss_span->high - ss_low + 1, FAIL);
 
@@ -11295,10 +11393,10 @@ H5S__hyper_proj_int_iterate(const H5S_hyper_span_info_t *ss_span_info,
             if(ss_span && !((depth == 0) && (u == count - 1))) {
                 /* Count remaining elements in ss_span_info */
                 if(ss_span->down) {
-                    H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, udata->op_gen) * (ss_span->high - ss_low + 1), FAIL);
+                    H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, 0, udata->op_gen) * (ss_span->high - ss_low + 1), FAIL);
                     ss_span = ss_span->next;
                     while(ss_span) {
-                        H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, udata->op_gen) * (ss_span->high - ss_span->low + 1), FAIL);
+                        H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper(ss_span->down, 0, udata->op_gen) * (ss_span->high - ss_span->low + 1), FAIL);
                         ss_span = ss_span->next;
                     } /* end while */
                 } /* end if */
@@ -11356,7 +11454,7 @@ H5S__hyper_proj_int_iterate(const H5S_hyper_span_info_t *ss_span_info,
     } /* end if */
     else if(depth > 0)
         /* Just count skipped elements */
-        H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper((H5S_hyper_span_info_t *)ss_span_info, udata->op_gen) * count, FAIL); /* Casting away const OK -NAF */
+        H5S_HYPER_PROJ_INT_ADD_SKIP(udata, H5S__hyper_spans_nelem_helper((H5S_hyper_span_info_t *)ss_span_info, 0, udata->op_gen) * count, FAIL); /* Casting away const OK -NAF */
 
     /* Clean up if we are done */
     if(depth == 0) {
@@ -11391,11 +11489,12 @@ done:
     src_intersect_space within the selection of src_space as a selection
     within the selection of dst_space
  USAGE
-    herr_t H5S__hyper_project_intersection(src_space,dst_space,src_intersect_space,proj_space)
+    herr_t H5S__hyper_project_intersection(src_space,dst_space,src_intersect_space,proj_space,share_selection)
         H5S_t *src_space;       IN: Selection that is mapped to dst_space, and intersected with src_intersect_space
         H5S_t *dst_space;       IN: Selection that is mapped to src_space, and which contains the result
         H5S_t *src_intersect_space; IN: Selection whose intersection with src_space is projected to dst_space to obtain the result
         H5S_t *proj_space;      OUT: Will contain the result (intersection of src_intersect_space and src_space projected from src_space to dst_space) after the operation
+        hbool_t share_selection; IN: Whether we are allowed to share structures inside dst_space with proj_space
  RETURNS
     Non-negative on success/Negative on failure.
  DESCRIPTION
@@ -11414,7 +11513,8 @@ done:
 --------------------------------------------------------------------------*/
 herr_t
 H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
-    const H5S_t *src_intersect_space, H5S_t *proj_space)
+    const H5S_t *src_intersect_space, H5S_t *proj_space,
+    hbool_t share_selection)
 {
     H5S_hyper_project_intersect_ud_t  udata; /* User data for subroutines */
     const H5S_hyper_span_info_t *ss_span_info;
@@ -11485,12 +11585,14 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
             HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "can't construct span tree for source intersect hyperslab selection")
 
     /* Initialize udata */
+    /* We will use op_info[0] for nelem and op_info[1] for copied spans */
     HDmemset(&udata, 0, sizeof(udata));
     udata.ds_span[0] = ds_span_info->head;
     udata.ds_low[0] = udata.ds_span[0]->low;
     udata.ss_rank = H5S_GET_EXTENT_NDIMS(src_space);
     udata.ds_rank = H5S_GET_EXTENT_NDIMS(dst_space);
     udata.op_gen = H5S__hyper_get_op_gen();
+    udata.share_selection = share_selection;
 
     /* Iterate over selections and build projected span tree */
     if(H5S__hyper_proj_int_iterate(ss_span_info, src_intersect_space->select.sel_info.hslab->span_lst, 1, 0, &udata) < 0)
diff --git a/src/H5Smpio.c b/src/H5Smpio.c
index f605a8a..800913f 100644
--- a/src/H5Smpio.c
+++ b/src/H5Smpio.c
@@ -86,7 +86,7 @@ static herr_t H5S__mpio_span_hyper_type(const H5S_t *space, size_t elmt_size,
 static herr_t H5S__release_datatype(H5S_mpio_mpitype_list_t *type_list);
 static herr_t H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
     size_t elmt_size, const MPI_Datatype *elmt_type, MPI_Datatype *span_type,
-    H5S_mpio_mpitype_list_t *type_list, uint64_t op_gen);
+    H5S_mpio_mpitype_list_t *type_list, unsigned op_info_i, uint64_t op_gen);
 
 
 /*****************************/
@@ -1007,8 +1007,10 @@ H5S__mpio_span_hyper_type(const H5S_t *space, size_t elmt_size,
     op_gen = H5S__hyper_get_op_gen();
 
     /* Obtain derived MPI data type */
+    /* Always use op_info[0] since we own this op_info, so there can be no
+     * simultaneous operations */
     type_list.head = type_list.tail = NULL;
-    if(H5S__obtain_datatype(space->select.sel_info.hslab->span_lst, down, elmt_size, &elmt_type, &span_type, &type_list, op_gen) < 0)
+    if(H5S__obtain_datatype(space->select.sel_info.hslab->span_lst, down, elmt_size, &elmt_type, &span_type, &type_list, 0, op_gen) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't obtain MPI derived data type")
     if(MPI_SUCCESS != (mpi_code = MPI_Type_dup(span_type, new_type)))
         HMPI_GOTO_ERROR(FAIL, "MPI_Type_commit failed", mpi_code)
@@ -1096,7 +1098,7 @@ done:
 static herr_t
 H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
     size_t elmt_size, const MPI_Datatype *elmt_type, MPI_Datatype *span_type,
-    H5S_mpio_mpitype_list_t *type_list, uint64_t op_gen)
+    H5S_mpio_mpitype_list_t *type_list, unsigned op_info_i, uint64_t op_gen)
 {
     H5S_hyper_span_t      *span;                /* Hyperslab span to iterate with */
     hsize_t               bigio_count;          /* Transition point to create derived type */
@@ -1119,7 +1121,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
 
     bigio_count = H5_mpi_get_bigio_count();
     /* Check if we've visited this span tree before */
-    if(spans->op_gen != op_gen) {
+    if(spans->op_info[op_info_i].op_gen != op_gen) {
         H5S_mpio_mpitype_node_t *type_node;     /* Pointer to new node in MPI data type list */
 
         /* Allocate the initial displacement & block length buffers */
@@ -1172,7 +1174,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
 
             /* Everything fits into integers, so cast them and use hindexed */
             if(bigio_count >= outercount && large_block == FALSE) {
-                if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hindexed((int)outercount, blocklen, disp, *elmt_type, &spans->u.down_type)))
+                if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hindexed((int)outercount, blocklen, disp, *elmt_type, &spans->op_info[op_info_i].u.down_type)))
                    HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hindexed failed", mpi_code)
             } /* end if */
             else {      /* LARGE_DATATYPE:: Something doesn't fit into a 32 bit integer */
@@ -1190,17 +1192,17 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
 
                     /* Combine the current datatype that is created with this current block type */
                     if(0 == u)      /* first iteration, there is no combined datatype yet */
-                        spans->u.down_type = temp_type;
+                        spans->op_info[op_info_i].u.down_type = temp_type;
                     else {
                         int bl[2] = {1, 1};
                         MPI_Aint ds[2] = {disp[u - 1], disp[u]};
-                        MPI_Datatype dt[2] = {spans->u.down_type, temp_type};
+                        MPI_Datatype dt[2] = {spans->op_info[op_info_i].u.down_type, temp_type};
 
                         if(MPI_SUCCESS != (mpi_code = MPI_Type_create_struct(2,              /* count */
                                                                              bl,             /* blocklength */
                                                                              ds,             /* stride in bytes*/
                                                                              dt,             /* old type */
-                                                                             &spans->u.down_type)))  /* new type */
+                                                                             &spans->op_info[op_info_i].u.down_type)))  /* new type */
                             HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_struct failed", mpi_code)
 
                         /* Release previous temporary datatype */
@@ -1253,7 +1255,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
                 blocklen[outercount]  = 1;
 
                 /* Generate MPI datatype for next dimension down */
-                if(H5S__obtain_datatype(span->down, down + 1, elmt_size, elmt_type, &down_type, type_list, op_gen) < 0)
+                if(H5S__obtain_datatype(span->down, down + 1, elmt_size, elmt_type, &down_type, type_list, op_info_i, op_gen) < 0)
                     HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't obtain MPI derived data type")
 
                 /* Compute the number of elements to attempt in this span */
@@ -1270,7 +1272,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
 
             /* Building the whole vector datatype */
             H5_CHECK_OVERFLOW(outercount, size_t, int)
-            if(MPI_SUCCESS != (mpi_code = MPI_Type_create_struct((int)outercount, blocklen, disp, inner_type, &spans->u.down_type)))
+            if(MPI_SUCCESS != (mpi_code = MPI_Type_create_struct((int)outercount, blocklen, disp, inner_type, &spans->op_info[op_info_i].u.down_type)))
                 HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_struct failed", mpi_code)
 
             /* Release inner node types */
@@ -1285,7 +1287,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate MPI data type list node")
 
         /* Set up MPI type node */
-        type_node->type = spans->u.down_type;
+        type_node->type = spans->op_info[op_info_i].u.down_type;
         type_node->next = NULL;
 
         /* Add MPI type node to list */
@@ -1297,11 +1299,11 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
         } /* end else */
 
         /* Remember that we've visited this span tree */
-        spans->op_gen = op_gen;
+        spans->op_info[op_info_i].op_gen = op_gen;
     } /* end else */
 
     /* Return MPI data type for span tree */
-    *span_type = spans->u.down_type;
+    *span_type = spans->op_info[op_info_i].u.down_type;
 
 done:
     /* General cleanup */
diff --git a/src/H5Spkg.h b/src/H5Spkg.h
index 278f08d..6809643 100644
--- a/src/H5Spkg.h
+++ b/src/H5Spkg.h
@@ -147,6 +147,21 @@ struct H5S_hyper_span_t {
     struct H5S_hyper_span_t *next;      /* Pointer to next span in list */
 };
 
+/* "Operation info" struct.  Used to hold temporary information during  copies,
+ * 'adjust', 'nelem', and 'rebuild' operations, and higher level algorithms that
+ * generate this information. */
+typedef struct H5S_hyper_op_info_t {
+    uint64_t op_gen;            /* Generation of the scratch info */
+    union {
+        struct H5S_hyper_span_info_t *copied;  /* Pointer to already copied span tree */
+        hsize_t nelmts;         /* # of elements */
+        hsize_t nblocks;        /* # of blocks */
+#ifdef H5_HAVE_PARALLEL
+        MPI_Datatype down_type; /* MPI datatype for span tree */
+#endif  /* H5_HAVE_PARALLEL */
+    }u;
+} H5S_hyper_op_info_t;
+
 /* Information about a list of hyperslab spans in one dimension (typedef'd in H5Sprivate.h) */
 struct H5S_hyper_span_info_t {
     unsigned count;     /* Ref. count of number of spans which share this span */
@@ -165,17 +180,10 @@ struct H5S_hyper_span_info_t {
     hsize_t *low_bounds;        /* The smallest element selected in each dimension */
     hsize_t *high_bounds;       /* The largest element selected in each dimension */
 
-    /* "Operation generation" fields */
+    /* "Operation info" fields */
     /* (Used during copies, 'adjust', 'nelem', and 'rebuild' operations) */
-    uint64_t op_gen;            /* Generation of the scratch info */
-    union {
-        struct H5S_hyper_span_info_t *copied;  /* Pointer to already copied span tree */
-        hsize_t nelmts;         /* # of elements */
-        hsize_t nblocks;        /* # of blocks */
-#ifdef H5_HAVE_PARALLEL
-        MPI_Datatype down_type; /* MPI datatype for span tree */
-#endif  /* H5_HAVE_PARALLEL */
-    }u;
+    /* Currently the maximum number of simultaneous operations is 2 */
+    H5S_hyper_op_info_t op_info[2];
 
     struct H5S_hyper_span_t *head;  /* Pointer to the first span of list of spans in the current dimension */
     struct H5S_hyper_span_t *tail;  /* Pointer to the last span of list of spans in the current dimension */
@@ -377,7 +385,8 @@ H5_DLL uint64_t H5S__hyper_get_op_gen(void);
 H5_DLL void H5S__hyper_rebuild(H5S_t *space);
 H5_DLL herr_t H5S__modify_select(H5S_t *space1, H5S_seloper_t op, H5S_t *space2);
 H5_DLL herr_t H5S__hyper_project_intersection(const H5S_t *src_space,
-    const H5S_t *dst_space, const H5S_t *src_intersect_space, H5S_t *proj_space);
+    const H5S_t *dst_space, const H5S_t *src_intersect_space, H5S_t *proj_space,
+    hbool_t share_space);
 
 /* Testing functions */
 #ifdef H5S_TESTING
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 3d68de0..41c8b95 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -261,7 +261,7 @@ H5_DLL herr_t H5S_select_project_scalar(const H5S_t *space, hsize_t *offset);
 H5_DLL herr_t H5S_select_project_simple(const H5S_t *space, H5S_t *new_space, hsize_t *offset);
 H5_DLL herr_t H5S_select_project_intersection(const H5S_t *src_space,
     const H5S_t *dst_space, const H5S_t *src_intersect_space,
-    H5S_t **new_space_ptr);
+    H5S_t **new_space_ptr, hbool_t share_space);
 H5_DLL herr_t H5S_select_subtract(H5S_t *space, H5S_t *subtract_space);
 
 /* Operations on all selections */
diff --git a/src/H5Spublic.h b/src/H5Spublic.h
index a04f3c1..263a880 100644
--- a/src/H5Spublic.h
+++ b/src/H5Spublic.h
@@ -172,6 +172,8 @@ H5_DLL hssize_t H5Sget_select_hyper_nblocks(hid_t spaceid);
 H5_DLL herr_t H5Sget_select_hyper_blocklist(hid_t spaceid, hsize_t startblock,
     hsize_t numblocks, hsize_t buf[/*numblocks*/]);
 H5_DLL herr_t H5Shyper_adjust_s(hid_t space_id, const hssize_t *offset);
+H5_DLL hid_t H5Sselect_project_intersection(hid_t src_space_id,
+    hid_t dst_space_id, hid_t src_intersect_space_id);
 
 /* Operations on dataspace selection iterators */
 H5_DLL hid_t H5Ssel_iter_create(hid_t spaceid, size_t elmt_size, unsigned flags);
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index 1a13f2c..c506218 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -2533,11 +2533,12 @@ done:
     within the selection of dst_space
 
  USAGE
-    herr_t H5S_select_project_intersection(src_space,dst_space,src_intersect_space,proj_space)
+    herr_t H5S_select_project_intersection(src_space,dst_space,src_intersect_space,proj_space,share_selection)
         H5S_t *src_space;       IN: Selection that is mapped to dst_space, and intersected with src_intersect_space
-        H5S_t *dst_space;       IN: Selection that is mapped to src_space, and which contains the result
+        H5S_t *dst_space;       IN: Selection that is mapped to src_space
         H5S_t *src_intersect_space; IN: Selection whose intersection with src_space is projected to dst_space to obtain the result
         H5S_t **new_space_ptr;  OUT: Will contain the result (intersection of src_intersect_space and src_space projected from src_space to dst_space) after the operation
+        hbool_t share_selection; IN: Whether we are allowed to share structures inside dst_space with proj_space
 
  RETURNS
     Non-negative on success/Negative on failure.
@@ -2555,7 +2556,8 @@ done:
 --------------------------------------------------------------------------*/
 herr_t
 H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
-    const H5S_t *src_intersect_space, H5S_t **new_space_ptr)
+    const H5S_t *src_intersect_space, H5S_t **new_space_ptr,
+    hbool_t share_selection)
 {
     H5S_t *new_space = NULL;           /* New dataspace constructed */
     herr_t ret_value = SUCCEED;         /* Return value */
@@ -2602,8 +2604,8 @@ H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
 
         /* Intersecting space is hyperslab selection.  Call the hyperslab
          * routine to project to another hyperslab selection. */
-        if(H5S__hyper_project_intersection(src_space, dst_space, src_intersect_space, new_space) < 0)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't project hyperslab ondot destination selection")
+        if(H5S__hyper_project_intersection(src_space, dst_space, src_intersect_space, new_space, share_selection) < 0)
+            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't project hyperslab onto destination selection")
     } /* end else */
 
     /* load the address of the new space into *new_space_ptr */
@@ -2621,6 +2623,75 @@ done:
 
 /*--------------------------------------------------------------------------
  NAME
+    H5Sselect_project_intersection
+
+ PURPOSE
+    Projects the intersection of of the selections of src_space_id and
+    src_intersect_space_id within the selection of src_space_id as a
+    selection within the selection of dst_space_id.  Currently does not
+    support point selections.
+
+ USAGE
+    hid_t H5Sselect_project_intersection(src_space_id,dst_space_d,src_intersect_space_id)
+        hid_t src_space_id;         IN: Selection that is mapped to dst_space_id, and intersected with src_intersect_space_id
+        hid_t dst_space_id;         IN: Selection that is mapped to src_space_id
+        hid_t src_intersect_space_id; IN: Selection whose intersection with src_space_id is projected to dst_space_id to obtain the result
+
+ RETURNS
+    A dataspace with a selection equal to the intersection of
+    src_intersect_space_id and src_space_id projected from src_space to
+    dst_space on success, negative on failure.
+
+ DESCRIPTION
+    Projects the intersection of of the selections of src_space and
+    src_intersect_space within the selection of src_space as a selection
+    within the selection of dst_space.  The result is placed in the
+    selection of new_space_ptr.
+
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+hid_t
+H5Sselect_project_intersection(hid_t src_space_id, hid_t dst_space_id,
+    hid_t src_intersect_space_id)
+{
+    H5S_t *src_space, *dst_space, *src_intersect_space; /* Input dataspaces */
+    H5S_t *proj_space = NULL;  /* Output dataspace */
+    hid_t ret_value;           /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("i", "iii", src_space_id, dst_space_id, src_intersect_space_id);
+
+    /* Check args */
+    if(NULL == (src_space = (H5S_t *)H5I_object_verify(src_space_id, H5I_DATASPACE)))
+        HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "not a dataspace")
+    if(NULL == (dst_space = (H5S_t *)H5I_object_verify(dst_space_id, H5I_DATASPACE)))
+        HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "not a dataspace")
+    if(NULL == (src_intersect_space = (H5S_t *)H5I_object_verify(src_intersect_space_id, H5I_DATASPACE)))
+        HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "not a dataspace")
+
+    /* Perform operation */
+    if(H5S_select_project_intersection(src_space, dst_space,
+            src_intersect_space, &proj_space, FALSE) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project dataspace intersection")
+
+    /* Atomize */
+    if((ret_value = H5I_register(H5I_DATASPACE, proj_space, TRUE)) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register dataspace atom")
+
+done:
+    if(ret_value < 0)
+        if(proj_space && H5S_close(proj_space) < 0)
+            HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release dataspace")
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Sselect_project_intersection() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
     H5S_select_subtract
 
  PURPOSE
@@ -2836,7 +2907,7 @@ H5Ssel_iter_get_seq_list(hid_t sel_iter_id, size_t maxseq, size_t maxbytes,
         HGOTO_ERROR(H5E_DATASPACE, H5E_BADVALUE, FAIL, "length array pointer is NULL")
 
     /* Get the sequences of bytes */
-    if(maxseq > 0 && maxbytes > 0) {
+    if(maxseq > 0 && maxbytes > 0 && sel_iter->elmt_left > 0) {
         if(H5S_SELECT_ITER_GET_SEQ_LIST(sel_iter, maxseq, maxbytes, nseq, nbytes, off, len) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "sequence length generation failed")
     } /* end if */
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index e582995..e5d12c0 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -137,6 +137,9 @@ H5Tcommit2(hid_t loc_id, const char *name, hid_t type_id, hid_t lcpl_id,
         if(TRUE != H5P_isa_class(tcpl_id, H5P_DATATYPE_CREATE))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not datatype creation property list")
 
+    /* Set the LCPL for the API context */
+    H5CX_set_lcpl(lcpl_id);
+
     /* Verify access property list and set up collective metadata if appropriate */
     if(H5CX_set_apl(&tapl_id, H5P_CLS_TACC, loc_id, TRUE) < 0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "can't set access property list info")
diff --git a/src/H5VLnative_link.c b/src/H5VLnative_link.c
index 5d5935d..2a8c27a 100644
--- a/src/H5VLnative_link.c
+++ b/src/H5VLnative_link.c
@@ -43,15 +43,10 @@ H5VL__native_link_create(H5VL_link_create_type_t create_type, void *obj,
     const H5VL_loc_params_t *loc_params, hid_t lcpl_id, hid_t H5_ATTR_UNUSED lapl_id,
     hid_t H5_ATTR_UNUSED dxpl_id, void H5_ATTR_UNUSED **req, va_list arguments)
 {
-    H5P_genplist_t   *plist;                     /* Property list pointer */
     herr_t           ret_value = SUCCEED;        /* Return value */
 
     FUNC_ENTER_PACKAGE
 
-    /* Get the plist structure */
-    if(NULL == (plist = (H5P_genplist_t *)H5I_object(lcpl_id)))
-        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
     switch(create_type) {
         case H5VL_LINK_CREATE_HARD:
             {
diff --git a/src/H5private.h b/src/H5private.h
index b5ee984..2b35bd4 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -2688,7 +2688,7 @@ H5_DLL herr_t   H5_combine_path(const char *path1, const char *path2, char **ful
 #ifdef H5_HAVE_PARALLEL
 /* Generic MPI functions */
 H5_DLL hsize_t  H5_mpi_set_bigio_count(hsize_t new_count);
-H5_DLL hsize_t  H5_mpi_get_bigio_count();
+H5_DLL hsize_t  H5_mpi_get_bigio_count(void);
 H5_DLL herr_t   H5_mpi_comm_dup(MPI_Comm comm, MPI_Comm *comm_new);
 H5_DLL herr_t   H5_mpi_info_dup(MPI_Info info, MPI_Info *info_new);
 H5_DLL herr_t   H5_mpi_comm_free(MPI_Comm *comm);