io/ompio: add verification for data representations.

check for providing a data representation that is actually supported
by ompio.

Add also one check for a non-NULL pointer in mpi/c/file_set_view
for the data representation.

Also fixes parts of issue #5643

Signed-off-by: Edgar Gabriel <egabriel@central.uh.edu>

ompi/mca/io/ompio/io_ompio_file_set_view.c

@@ -9,7 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
- * Copyright (c) 2008-2016 University of Houston. All rights reserved.
+ * Copyright (c) 2008-2018 University of Houston. All rights reserved.
  * Copyright (c) 2015-2018 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2016-2017 IBM Corporation. All rights reserved.
@@ -66,6 +66,10 @@ int mca_io_ompio_file_set_view (ompi_file_t *fp,
     mca_common_ompio_data_t *data;
     ompio_file_t *fh;
 
+    if ( (strcmp(datarep, "native") && strcmp(datarep, "NATIVE"))) {
+        return MPI_ERR_UNSUPPORTED_DATAREP;
+    }
+
     data = (mca_common_ompio_data_t *) fp->f_io_selected_data;
 
     /* we need to call the internal file set view twice: once for the individual

ompi/mpi/c/file_set_view.c

@@ -64,6 +64,10 @@ int MPI_File_set_view(MPI_File fh, MPI_Offset disp, MPI_Datatype etype,
                OMPI_CHECK_DATATYPE_FOR_VIEW(rc, filetype, 0);
            }
         }
+        if ( NULL == datarep) {
+            rc = MPI_ERR_UNSUPPORTED_DATAREP;
+            fh = MPI_FILE_NULL;            
+        }
         OMPI_ERRHANDLER_CHECK(rc, fh, rc, FUNC_NAME);
     }