[svn-r26411] Add support for I/O in very simple cases (virtual mapping and file space are

both H5S_ALL).
Note make check  fails in h5dump test (unrelated to this checkin).

Tested: ummon

8 files changed, 411 insertions, 56 deletions

diff --git a/src/H5D.c b/src/H5D.c
index a81fb8b..d19e3a6 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -323,14 +323,9 @@ hid_t
 H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
 {
     H5D_t       *dset = NULL;
-    H5G_loc_t	 loc;		        /* Object location of group */
-    H5G_loc_t	 dset_loc;		/* Object location of dataset */
-    H5G_name_t   path;            	/* Dataset group hier. path */
-    H5O_loc_t    oloc;            	/* Dataset object location */
-    H5O_type_t   obj_type;              /* Type of object at location */
-    hbool_t      loc_found = FALSE;     /* Location at 'name' found */
-    hid_t        dxpl_id = H5AC_dxpl_id;    /* dxpl to use to open datset */
-    hid_t        ret_value;
+    H5G_loc_t   loc;                    /* Object location of group */
+    hid_t       dxpl_id = H5AC_dxpl_id; /* dxpl to use to open datset */
+    hid_t       ret_value;
 
     FUNC_ENTER_API(FAIL)
     H5TRACE3("i", "i*si", loc_id, name, dapl_id);
@@ -348,41 +343,18 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
         if(TRUE != H5P_isa_class(dapl_id, H5P_DATASET_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not dataset access property list")
 
-    /* Set up dataset location to fill in */
-    dset_loc.oloc = &oloc;
-    dset_loc.path = &path;
-    H5G_loc_reset(&dset_loc);
-
-    /* Find the dataset object */
-    if(H5G_loc_find(&loc, name, &dset_loc, dapl_id, dxpl_id) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "not found")
-    loc_found = TRUE;
-
-    /* Check that the object found is the correct type */
-    if(H5O_obj_type(&oloc, &obj_type, dxpl_id) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get object type")
-    if(obj_type != H5O_TYPE_DATASET)
-        HGOTO_ERROR(H5E_DATASET, H5E_BADTYPE, FAIL, "not a dataset")
-
     /* Open the dataset */
-    if(NULL == (dset = H5D_open(&dset_loc, dapl_id, dxpl_id)))
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't open dataset")
+    if(NULL == (dset = H5D__open_name(&loc, name, dapl_id, dxpl_id)))
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open dataset")
 
     /* Register an atom for the dataset */
     if((ret_value = H5I_register(H5I_DATASET, dset, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "can't register dataset atom")
 
 done:
-    if(ret_value < 0) {
-        if(dset) {
-            if(H5D_close(dset) < 0)
-                HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
-        } /* end if */
-        else {
-            if(loc_found && H5G_loc_free(&dset_loc) < 0)
-                HDONE_ERROR(H5E_DATASET, H5E_CANTRELEASE, FAIL, "can't free location")
-        } /* end else */
-    } /* end if */
+    if(ret_value < 0)
+        if(dset && H5D_close(dset) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
 
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dopen2() */
diff --git a/src/H5Dint.c b/src/H5Dint.c
index 5035a67..a36b8b3 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -1105,6 +1105,69 @@ done:
 } /* end H5D__create() */
 
 
+/*-------------------------------------------------------------------------
+ * Function:    H5D__open_name
+ *
+ * Purpose:     Opens an existing dataset by name.
+ *
+ * Return:      Success:        Ptr to a new dataset.
+ *              Failure:        NULL
+ *
+ * Programmer:  Neil Fortner
+ *              Friday, March 6, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+H5D_t *
+H5D__open_name(const H5G_loc_t *loc, const char *name, hid_t dapl_id,
+    hid_t dxpl_id)
+{
+    H5D_t       *dset = NULL;
+    H5G_loc_t   dset_loc;               /* Object location of dataset */
+    H5G_name_t  path;                   /* Dataset group hier. path */
+    H5O_loc_t   oloc;                   /* Dataset object location */
+    H5O_type_t  obj_type;               /* Type of object at location */
+    hbool_t     loc_found = FALSE;      /* Location at 'name' found */
+    H5D_t       *ret_value;             /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Check args */
+    HDassert(loc);
+    HDassert(name);
+
+    /* Set up dataset location to fill in */
+    dset_loc.oloc = &oloc;
+    dset_loc.path = &path;
+    H5G_loc_reset(&dset_loc);
+
+    /* Find the dataset object */
+    if(H5G_loc_find(loc, name, &dset_loc, dapl_id, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, NULL, "not found")
+    loc_found = TRUE;
+
+    /* Check that the object found is the correct type */
+    if(H5O_obj_type(&oloc, &obj_type, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, NULL, "can't get object type")
+    if(obj_type != H5O_TYPE_DATASET)
+        HGOTO_ERROR(H5E_DATASET, H5E_BADTYPE, NULL, "not a dataset")
+
+    /* Open the dataset */
+    if(NULL == (dset = H5D_open(&dset_loc, dapl_id, dxpl_id)))
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "can't open dataset")
+
+    /* Set return value */
+    ret_value = dset;
+
+done:
+    if(!ret_value)
+        if(loc_found && H5G_loc_free(&dset_loc) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CANTRELEASE, NULL, "can't free location")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5D__open_name() */
+
+
 /*
  *-------------------------------------------------------------------------
  * Function:	H5D_open
@@ -1449,8 +1512,21 @@ H5D_close(H5D_t *dataset)
                 break;
 
             case H5D_VIRTUAL:
-                /* Close datasets here?  VDSINC */
-                break;
+            {
+                size_t i;
+
+                HDassert(dataset->shared->layout.storage.u.virt.list || (dataset->shared->layout.storage.u.virt.list_nused == 0));
+
+                /* Close source datasets */
+                for(i = 0; i < dataset->shared->layout.storage.u.virt.list_nused; i++)
+                    if(dataset->shared->layout.storage.u.virt.list[i].source_dset) {
+                        HDassert(dataset->shared->layout.storage.u.virt.list[i].source_dset != dataset);
+                        if(H5D_close(dataset->shared->layout.storage.u.virt.list[i].source_dset) < 0)
+                            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to close source dataset")
+                        dataset->shared->layout.storage.u.virt.list[i].source_dset = NULL;
+                    } /* end if */
+            } /* end block */
+            break;
 
             case H5D_LAYOUT_ERROR:
             case H5D_NLAYOUTS:
diff --git a/src/H5Dio.c b/src/H5Dio.c
index 88f75b1..296e529 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -52,9 +52,6 @@
 /********************/
 
 /* Internal I/O routines */
-static herr_t H5D__write(H5D_t *dataset, hid_t mem_type_id,
-    const H5S_t *mem_space, const H5S_t *file_space, hid_t dset_xfer_plist,
-    const void *buf);
 static herr_t H5D__pre_write(H5D_t *dset, hbool_t direct_write, hid_t mem_type_id, 
     const H5S_t *mem_space, const H5S_t *file_space, hid_t dxpl_id, const void *buf);
 
@@ -586,7 +583,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5D__write(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
 	  const H5S_t *file_space, hid_t dxpl_id, const void *buf)
 {
diff --git a/src/H5Dpkg.h b/src/H5Dpkg.h
index 82c4d2f..d448406 100644
--- a/src/H5Dpkg.h
+++ b/src/H5Dpkg.h
@@ -536,6 +536,8 @@ H5_DLL H5D_t *H5D__create(H5F_t *file, hid_t type_id, const H5S_t *space,
 H5_DLL H5D_t *H5D__create_named(const H5G_loc_t *loc, const char *name,
     hid_t type_id, const H5S_t *space, hid_t lcpl_id, hid_t dcpl_id,
     hid_t dapl_id, hid_t dxpl_id);
+H5_DLL H5D_t *H5D__open_name(const H5G_loc_t *loc, const char *name,
+    hid_t dapl_id, hid_t dxpl_id);
 H5_DLL herr_t H5D__get_space_status(H5D_t *dset, H5D_space_status_t *allocation,
     hid_t dxpl_id);
 H5_DLL herr_t H5D__alloc_storage(const H5D_t *dset, hid_t dxpl_id, H5D_time_alloc_t time_alloc,
@@ -558,6 +560,9 @@ H5_DLL herr_t H5D__flush_real(H5D_t *dataset, hid_t dxpl_id);
 H5_DLL herr_t H5D__read(H5D_t *dataset, hid_t mem_type_id,
     const H5S_t *mem_space, const H5S_t *file_space, hid_t dset_xfer_plist,
     void *buf/*out*/);
+H5_DLL herr_t H5D__write(H5D_t *dataset, hid_t mem_type_id,
+    const H5S_t *mem_space, const H5S_t *file_space, hid_t dset_xfer_plist,
+    const void *buf);
 
 /* Functions that perform direct serial I/O operations */
 H5_DLL herr_t H5D__select_read(const H5D_io_info_t *io_info,
diff --git a/src/H5Dvirtual.c b/src/H5Dvirtual.c
index 1bc4b75..ac7af54 100644
--- a/src/H5Dvirtual.c
+++ b/src/H5Dvirtual.c
@@ -35,6 +35,7 @@
 #include "H5Dpkg.h"             /* Dataset functions                    */
 #include "H5Eprivate.h"         /* Error handling                       */
 #include "H5Fprivate.h"         /* Files                                */
+#include "H5Gprivate.h"         /* Groups                               */
 #include "H5HGprivate.h"        /* Global Heaps                         */
 #include "H5MMprivate.h"        /* Memory management                    */
 #include "H5Oprivate.h"         /* Object headers                       */
@@ -68,6 +69,10 @@ static herr_t H5D__virtual_write(H5D_io_info_t *io_info,
     const H5S_t *mem_space, H5D_chunk_map_t *fm);
 static herr_t H5D__virtual_flush(H5D_t *dset, hid_t dxpl_id);
 
+/* Other functions */
+static htri_t H5D__virtual_open_source_dset(const H5D_t *vdset,
+    H5O_storage_virtual_ent_t *virtual_ent, hid_t dxpl_id);
+
 
 /*********************/
 /* Package Variables */
@@ -171,6 +176,68 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5D__virtual_open_source_dset
+ *
+ * Purpose:     Attempts to open a source dataset.
+ *
+ * Return:      TRUE: Source dataset opened
+ *              FALSE: Source dataset not opened
+ *              Negative: Error
+ *
+ * Programmer:  Neil Fortner
+ *              March 6, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+static htri_t
+H5D__virtual_open_source_dset(const H5D_t *vdset,
+    H5O_storage_virtual_ent_t *virtual_ent, hid_t dxpl_id)
+{
+    H5F_t       *src_file = NULL;       /* Source file */
+    hbool_t     src_file_open = FALSE;  /* Whether we have opened and need to close src_file */
+    H5G_loc_t   src_root_loc;           /* Object location of source file root group */
+    htri_t      ret_value = TRUE;       /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(virtual_ent);
+    HDassert(!virtual_ent->source_dset);
+
+    /* Get dapl and fapl from current (virtual dataset) location? VDSINC */
+    /* Write code to check if these exist and return FALSE otherwise VDSINC */
+
+    /* Check if we need to open the source file */
+    if(HDstrcmp(virtual_ent->source_file_name, ".")) {
+        /* Open the source file */
+        if(NULL == (src_file = H5F_open(virtual_ent->source_file_name, H5F_ACC_RDONLY, H5P_FILE_CREATE_DEFAULT, H5P_FILE_ACCESS_DEFAULT, dxpl_id)))
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENFILE, FAIL, "unable to open source file")
+        src_file_open = TRUE;
+    } /* end if */
+    else
+        /* Source file is ".", use the virtual dataset's file */
+        src_file = vdset->oloc.file;
+
+    /* Set up the root group in the destination file */
+    if(NULL == (src_root_loc.oloc = H5G_oloc(H5G_rootof(src_file))))
+        HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "unable to get object location for root group")
+    if(NULL == (src_root_loc.path = H5G_nameof(H5G_rootof(src_file))))
+        HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "unable to get path for root group")
+
+    /* Open the source dataset */
+    if(NULL == (virtual_ent->source_dset = H5D__open_name(&src_root_loc, virtual_ent->source_dset_name, H5P_DATASET_ACCESS_DEFAULT, dxpl_id)))
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open dataset")
+
+done:
+    if(src_file_open)
+        if(H5F_try_close(src_file) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEFILE, FAIL, "can't close source file")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5D__virtual_open_source_dset() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5D__virtual_reset_layout
  *
  * Purpose:     Frees internal structures in a virtual storage layout
@@ -307,7 +374,7 @@ H5D__virtual_is_space_alloc(const H5O_storage_t *storage)
 
     /* Need to decide what to do here.  For now just return TRUE if the global
      * heap block has been allocated.  VDSINC */
-    ret_value = storage->u.virt.serial_list_hobjid.addr != HADDR_UNDEF;
+    ret_value = TRUE;//storage->u.virt.serial_list_hobjid.addr != HADDR_UNDEF;
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_is_space_alloc() */
@@ -332,7 +399,7 @@ H5D__virtual_io_init(const H5D_io_info_t UNUSED *io_info, const H5D_type_info_t
 {
     FUNC_ENTER_STATIC_NOERR
 
-    HDassert(0 && "Not yet implemented...");//VDSINC
+    /* No-op for now.  Delete if we never add anything here. VDSINC */
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5D__virtual_io_init() */
@@ -350,16 +417,86 @@ H5D__virtual_io_init(const H5D_io_info_t UNUSED *io_info, const H5D_type_info_t
  *
  *-------------------------------------------------------------------------
  */
-herr_t
-H5D__virtual_read(H5D_io_info_t UNUSED *io_info, const H5D_type_info_t UNUSED *type_info,
-    hsize_t UNUSED nelmts, const H5S_t UNUSED *file_space, const H5S_t UNUSED *mem_space,
+static herr_t
+H5D__virtual_read(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
+    hsize_t UNUSED nelmts, const H5S_t *file_space, const H5S_t *mem_space,
     H5D_chunk_map_t UNUSED *fm)
 {
-    FUNC_ENTER_PACKAGE_NOERR
+    H5O_storage_virtual_t *storage;         /* Convenient pointer into layout struct */
+    H5S_t       *projected_mem_space = NULL; /* Memory space for selection in a single mapping */
+    H5S_t       *projected_src_space = NULL; /* File space for selection in a single source dataset */
+    hssize_t    select_nelmts;              /* Number of elements in selection */
+    htri_t      opened_dset;                /* Whether we opened the source dataset */
+    size_t      i;                          /* Local index variable */
+    herr_t      ret_value = SUCCEED;        /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(io_info);
+    HDassert(io_info->u.rbuf);
+    HDassert(type_info);
+    HDassert(mem_space);
+    HDassert(file_space);
+
+    storage = &io_info->dset->shared->layout.storage.u.virt;
+
+    /* Iterate over mappings */
+    for(i = 0; i < storage->list_nused; i++) {
+        /* Project intersection of file space and mapping virtual space onto
+         * memory space */
+        if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].virtual_select, &projected_mem_space) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto memory space")
+
+            /* Get number of elements in projected dataspace */
+        if((select_nelmts = (hssize_t)H5S_GET_SELECT_NPOINTS(projected_mem_space)) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTCOUNT, FAIL, "unable to get number of elements in selection")
+
+        /* Only perform I/O if there are any elements */
+        if(nelmts > 0) {
+            /* Open source dataset, fail if cannot open */
+            if(!storage->list[i].source_dset) {
+                if((opened_dset = H5D__virtual_open_source_dset(io_info->dset, &storage->list[i], io_info->dxpl_id)) < 0)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open source dataset")
+                if(!opened_dset)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "did not open source dataset")
+            } /* end if */
+
+            /* Project intersection of file space and mapping virtual space onto
+             * mapping source space */
+            if(H5S_select_project_intersection(storage->list[i].virtual_select, storage->list[i].source_select, file_space, &projected_src_space) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto source space")
+
+            /* Perform read on source dataset */
+            if(H5D__read(storage->list[i].source_dset, type_info->dst_type_id, projected_mem_space, projected_src_space, io_info->dxpl_id, io_info->u.rbuf) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read source dataset")
+
+            /* Close projected_src_space */
+            if(H5S_close(projected_src_space) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected source space")
+            projected_src_space = NULL;
+        } /* end if */
+
+        /* Close projected_mem_space */
+        if(H5S_close(projected_mem_space) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected memory space")
+        projected_mem_space = NULL;
+    } /* end for */
 
-    HDassert(0 && "Not yet implemented...");//VDSINC
+done:
+    /* Release allocated resources on failure */
+    if(projected_src_space) {
+        HDassert(ret_value < 0);
+        if(H5S_close(projected_src_space) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected source space")
+    } /* end if */
+    if(projected_mem_space) {
+        HDassert(ret_value < 0);
+        if(H5S_close(projected_mem_space) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected memory space")
+    } /* end if */
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_read() */
 
 
@@ -375,16 +512,86 @@ H5D__virtual_read(H5D_io_info_t UNUSED *io_info, const H5D_type_info_t UNUSED *t
  *
  *-------------------------------------------------------------------------
  */
-herr_t
-H5D__virtual_write(H5D_io_info_t UNUSED *io_info, const H5D_type_info_t UNUSED *type_info,
-    hsize_t UNUSED nelmts, const H5S_t UNUSED *file_space, const H5S_t UNUSED *mem_space,
+static herr_t
+H5D__virtual_write(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
+    hsize_t UNUSED nelmts, const H5S_t *file_space, const H5S_t *mem_space,
     H5D_chunk_map_t UNUSED *fm)
 {
-    FUNC_ENTER_PACKAGE_NOERR
+    H5O_storage_virtual_t *storage;         /* Convenient pointer into layout struct */
+    H5S_t       *projected_mem_space = NULL; /* Memory space for selection in a single mapping */
+    H5S_t       *projected_src_space = NULL; /* File space for selection in a single source dataset */
+    hssize_t    select_nelmts;              /* Number of elements in selection */
+    htri_t      opened_dset;                /* Whether we opened the source dataset */
+    size_t      i;                          /* Local index variable */
+    herr_t      ret_value = SUCCEED;        /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(io_info);
+    HDassert(io_info->u.rbuf);
+    HDassert(type_info);
+    HDassert(mem_space);
+    HDassert(file_space);
+
+    storage = &io_info->dset->shared->layout.storage.u.virt;
+
+    /* Iterate over mappings */
+    for(i = 0; i < storage->list_nused; i++) {
+        /* Project intersection of file space and mapping virtual space onto
+         * memory space */
+        if(H5S_select_project_intersection(file_space, mem_space, storage->list[i].virtual_select, &projected_mem_space) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto memory space")
+
+            /* Get number of elements in projected dataspace */
+        if((select_nelmts = (hssize_t)H5S_GET_SELECT_NPOINTS(projected_mem_space)) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTCOUNT, FAIL, "unable to get number of elements in selection")
+
+        /* Only perform I/O if there are any elements */
+        if(nelmts > 0) {
+            /* Open source dataset, fail if cannot open */
+            if(!storage->list[i].source_dset) {
+                if((opened_dset = H5D__virtual_open_source_dset(io_info->dset, &storage->list[i], io_info->dxpl_id)) < 0)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open source dataset")
+                if(!opened_dset)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "did not open source dataset")
+            } /* end if */
+
+            /* Project intersection of file space and mapping virtual space onto
+             * mapping source space */
+            if(H5S_select_project_intersection(storage->list[i].virtual_select, storage->list[i].source_select, file_space, &projected_src_space) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTCLIP, FAIL, "can't project virtual intersection onto source space")
+
+            /* Perform read on source dataset */
+            if(H5D__write(storage->list[i].source_dset, type_info->dst_type_id, projected_mem_space, projected_src_space, io_info->dxpl_id, io_info->u.wbuf) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write to source dataset")
+
+            /* Close projected_src_space */
+            if(H5S_close(projected_src_space) < 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected source space")
+            projected_src_space = NULL;
+        } /* end if */
+
+        /* Close projected_mem_space */
+        if(H5S_close(projected_mem_space) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected memory space")
+        projected_mem_space = NULL;
+    } /* end for */
 
-    HDassert(0 && "Not yet implemented...");//VDSINC
+done:
+    /* Release allocated resources on failure */
+    if(projected_src_space) {
+        HDassert(ret_value < 0);
+        if(H5S_close(projected_src_space) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected source space")
+    } /* end if */
+    if(projected_mem_space) {
+        HDassert(ret_value < 0);
+        if(H5S_close(projected_mem_space) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "can't close projected memory space")
+    } /* end if */
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_write() */
 
 
diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index de3ab86..9c5833d 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -1615,6 +1615,8 @@ H5Pset_virtual(hid_t dcpl_id, hid_t vspace_id, const char *src_file_name,
     if(NULL == (src_space = (H5S_t *)H5I_object_verify(src_space_id, H5I_DATASPACE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataspace")
 
+    //VDSINC add check for overlaping virtual spaces
+
 #ifndef H5_HAVE_C99_DESIGNATED_INITIALIZER
     /* If the compiler doesn't support C99 designated initializers, check if
      *  the default layout structs have been initialized yet or not.  *ick* -QAK
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 7cb5285..6ce2821 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -235,6 +235,9 @@ H5_DLL htri_t H5S_select_is_regular(const H5S_t *space);
 H5_DLL herr_t H5S_select_adjust_u(H5S_t *space, const hsize_t *offset);
 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);
 
 /* Operations on all selections */
 H5_DLL herr_t H5S_select_all(H5S_t *space, hbool_t rel_prev);
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index a4f13d7..4085e7f 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -2101,3 +2101,96 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* H5S_select_fill() */
 
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5S_select_project_intersection
+
+ PURPOSE
+    VDSINC
+
+ USAGE
+    VDSINC
+
+ RETURNS
+    Non-negative on success/Negative on failure.
+
+ DESCRIPTION
+    VDSINC
+    
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+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 = NULL;           /* New dataspace constructed */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity checks */
+    HDassert(src_space);
+    HDassert(dst_space);
+    HDassert(src_intersect_space);
+    HDassert(new_space_ptr);
+
+    /* Create new space, using dst extent.  Start wil "all" selection. */
+    if(NULL == (new_space = H5S_create(H5S_SIMPLE)))
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "unable to create output dataspace")
+    if(H5S_extent_copy_real(&new_space->extent, &dst_space->extent, TRUE) < 0)
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy destination space extent")
+
+    /* Check intersecting space's selection type */
+    switch(src_intersect_space->select.type->type) {
+        case H5S_SEL_NONE:
+            /* Since the intersecting space is "none", the intersection has no
+             * selection and so does the projection.  Change to "none" selection
+             */
+            if(H5S_select_none(new_space) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
+
+            break;
+
+        case H5S_SEL_POINTS:
+            HDassert(0 && "Not yet implemented...");//VDSINC
+
+            break;
+
+        case H5S_SEL_HYPERSLABS:
+            HDassert(0 && "Not yet implemented...");//VDSINC
+
+            break;
+
+        case H5S_SEL_ALL:
+            /* Since the intersecting space is "all", the intersection must be
+             * equal to the source space and the projection must be equal to the
+             * destination space.  Copy the destination selection.
+             */
+            if(H5S_select_copy(new_space, dst_space, FALSE) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination space selection")
+
+            break;
+
+        case H5S_SEL_ERROR:
+        case H5S_SEL_N:
+        default:
+            HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "invalid source dataspace selection type")
+    } /* end switch */
+
+    /* load the address of the new space into *new_space_ptr */
+    *new_space_ptr = new_space;
+
+done:
+    /* Cleanup on error */
+    if(ret_value < 0) {
+        if(new_space && H5S_close(new_space) < 0)
+            HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release dataspace")
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5S_select_project_intersection() */
+