/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *
 *  (C) 2003 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 *
 */
#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include "mpitest.h"

static char MTEST_Descrip[] = "Test writing and reading an integer a particular file offset";

int main( int argc, char *argv[] )
{
    int errs = 0;
    int size, rank, i, errcode;
    MPI_File fh1, fh2;
    MPI_Comm comm;
    MPI_Status status;

    MTest_Init( &argc, &argv );

    comm = MPI_COMM_WORLD;

    MPI_Comm_size( comm, &size );
    MPI_Comm_rank( comm, &rank );

    MPI_File_open( comm, "test.at", 
		   MPI_MODE_WRONLY | MPI_MODE_CREATE,
		   MPI_INFO_NULL, &fh1 );

    MPI_File_write_at( fh1, rank * sizeof(int), &rank, 1, MPI_INT, &status );

    MPI_File_close( &fh1 );

    MPI_Barrier(comm);

    errcode = MPI_File_open( comm, "test.at", 
		   MPI_MODE_RDONLY | MPI_MODE_DELETE_ON_CLOSE,
		   MPI_INFO_NULL, &fh2 );
    if (errcode != MPI_SUCCESS) {
      char str[MPI_MAX_ERROR_STRING];
      int len;
      MPI_Error_string( errcode, str, &len);
      errs++;
      fprintf( stderr, "%d: MPI_File_open() failed: %s\n", rank, str );
    } else {
      MPI_File_read_at( fh2, rank * sizeof(int), &i, 1, MPI_INT, &status );
      if (i != rank) {
        errs++;
        fprintf( stderr, "%d: i = %d\n", rank, i );
      }
      MPI_File_close( &fh2 );
    }

    MTest_Finalize( errs );
    MPI_Finalize();
    return 0;
}