From 9daec82f17f5b204d9f64701e62473349e14b6c3 Mon Sep 17 00:00:00 2001
From: Edgar Gabriel <gabriel@cs.uh.edu>
Date: Thu, 30 May 2013 21:33:13 +0000
Subject: [PATCH] - make a fileview of 0 bytes work in ompio - fixes the bug
 reported in ticket 3619 (which is already closed) also for ompio

This commit was SVN r28575.
---
 ompi/mca/io/ompio/io_ompio.c               | 8 ++++++++
 ompi/mca/io/ompio/io_ompio_file_read.c     | 9 +++++++--
 ompi/mca/io/ompio/io_ompio_file_set_view.c | 4 +++-
 ompi/mca/io/ompio/io_ompio_file_write.c    | 9 ++++++++-
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/ompi/mca/io/ompio/io_ompio.c b/ompi/mca/io/ompio/io_ompio.c
index 415580a4f4..5faba1ae54 100644
--- a/ompi/mca/io/ompio/io_ompio.c
+++ b/ompi/mca/io/ompio/io_ompio.c
@@ -491,6 +491,14 @@ int ompi_io_ompio_decode_datatype (mca_io_ompio_file_t *fh,
         opal_output (1, "Cannot attach the datatype to a convertor\n");
         return OMPI_ERROR;
     }
+
+    if ( 0 == datatype->super.size ) {
+	*max_data = 0;
+	*iovec_count = 0;
+	*iov = NULL;
+	return OMPI_SUCCESS;
+    }
+
     remaining_length = count * datatype->super.size;
 
     temp_count = OMPIO_IOVEC_INITIAL_SIZE;
diff --git a/ompi/mca/io/ompio/io_ompio_file_read.c b/ompi/mca/io/ompio/io_ompio_file_read.c
index fd31b67b96..ef1b5e61df 100644
--- a/ompi/mca/io/ompio/io_ompio_file_read.c
+++ b/ompi/mca/io/ompio/io_ompio_file_read.c
@@ -62,11 +62,17 @@ mca_io_ompio_file_read (ompi_file_t *fp,
     data = (mca_io_ompio_data_t *) fp->f_io_selected_data;
     fh = &data->ompio_fh;
 
+    if ( 0 == count ) {
+	if ( MPI_STATUS_IGNORE != status ) {
+	    status->_ucount = max_data;
+	}
+	return ret;
+    }
 
     if (fh->f_amode & MPI_MODE_WRONLY){
       printf("Improper use of FILE Mode, Using WRONLY for Read!\n");
       ret = OMPI_ERROR;
-      goto exit;
+      return ret;
     }
 
     ompi_io_ompio_decode_datatype (fh, 
@@ -218,7 +224,6 @@ mca_io_ompio_file_read (ompi_file_t *fp,
 	status->_ucount = max_data;
     }
 
- exit:
     return ret;
 }
 
diff --git a/ompi/mca/io/ompio/io_ompio_file_set_view.c b/ompi/mca/io/ompio/io_ompio_file_set_view.c
index c4eee8b2fe..1b554d402a 100644
--- a/ompi/mca/io/ompio/io_ompio_file_set_view.c
+++ b/ompi/mca/io/ompio/io_ompio_file_set_view.c
@@ -167,7 +167,9 @@ OMPI_MPI_OFFSET_TYPE get_contiguous_chunk_size (mca_io_ompio_file_t *fh)
             }
         }
     }
-    avg = avg/fh->f_iov_count;
+    if ( 0 != fh->f_iov_count ) {
+	avg = avg/fh->f_iov_count;
+    }
     fh->f_comm->c_coll.coll_allreduce (&avg,
                                        &global_avg,
                                        1,
diff --git a/ompi/mca/io/ompio/io_ompio_file_write.c b/ompi/mca/io/ompio/io_ompio_file_write.c
index 23b1f6bda5..f3508d5628 100644
--- a/ompi/mca/io/ompio/io_ompio_file_write.c
+++ b/ompi/mca/io/ompio/io_ompio_file_write.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) 2008-2012 University of Houston. All rights reserved.
+ *  Copyright (c) 2008-2013 University of Houston. All rights reserved.
  *  $COPYRIGHT$
  *  
  *  Additional copyrights may follow
@@ -59,6 +59,13 @@ mca_io_ompio_file_write (ompi_file_t *fp,
     size_t sum_previous_counts = 0;
     size_t sum_previous_length = 0;
 
+    if ( 0 == count ) {
+	if ( MPI_STATUS_IGNORE != status ) {
+	    status->_ucount = 0;
+	}
+	return ret;
+    }
+
     data = (mca_io_ompio_data_t *) fp->f_io_selected_data;
     fh = &data->ompio_fh;