text: /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
  /*
   *  (C) 2014 by Argonne National Laboratory.
   *      See COPYRIGHT in top-level directory.
   */
  #include <mpi.h>
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #include <unistd.h>
  
  #define DATA_SIZE 324*4
  #define PAD 256
  #define HEADER 144
  #define BLK_COUNT 3
  
  static void handle_error(int errcode, char *str)
  {
      char msg[MPI_MAX_ERROR_STRING];
      int resultlen;
      MPI_Error_string(errcode, msg, &resultlen);
      fprintf(stderr, "%s: %s\n", str, msg);
      MPI_Abort(MPI_COMM_WORLD, 1);
  }
  
  #define CHECK(fn) { int errcode; errcode = (fn); if (errcode != MPI_SUCCESS) handle_error(errcode, #fn); }
  
  int main(int argc, char **argv)
  {
      MPI_File fh;
      MPI_Datatype file_type, mem_type;
      int *data = NULL;
      int *verify = NULL;
      int data_size = DATA_SIZE;
      int i, j, k, nr_errors = 0;
      MPI_Aint disp[BLK_COUNT];
      int block_lens[BLK_COUNT];
      char *filename = "unnamed.dat";
      MPI_Status status;
      MPI_Request request;
  
      MPI_Init(&argc, &argv);
      disp[0] = (MPI_Aint) (PAD);
      disp[1] = (MPI_Aint) (data_size * 1 + PAD);
      disp[2] = (MPI_Aint) (data_size * 2 + PAD);
  
      block_lens[0] = data_size;
      block_lens[1] = data_size;
      block_lens[2] = data_size;
  
      data = malloc(data_size);
      verify = malloc(data_size * BLK_COUNT + HEADER + PAD);
      for (i = 0; i < data_size / sizeof(int); i++)
          data[i] = i;
  
      MPI_Type_create_hindexed_block(BLK_COUNT, data_size, disp, MPI_BYTE, &file_type);
      MPI_Type_commit(&file_type);
  
      MPI_Type_create_hvector(BLK_COUNT, data_size, 0, MPI_BYTE, &mem_type);
      MPI_Type_commit(&mem_type);
  
      if (1 < argc)
          filename = argv[1];
  
      CHECK(MPI_File_open(MPI_COMM_WORLD, filename,
                          MPI_MODE_RDWR | MPI_MODE_CREATE | MPI_MODE_DELETE_ON_CLOSE,
                          MPI_INFO_NULL, &fh) != 0);
  
      CHECK(MPI_File_set_view(fh, HEADER, MPI_BYTE, file_type, "native", MPI_INFO_NULL));
  
      /* write everything */
      CHECK(MPI_File_iwrite_at_all(fh, 0, data, 1, mem_type, &request));
      MPI_Wait(&request, &status);
  
      /* verify */
      CHECK(MPI_File_set_view(fh, 0, MPI_BYTE, MPI_BYTE, "native", MPI_INFO_NULL));
      CHECK(MPI_File_iread_at_all(fh, 0,
                                  verify, (HEADER + PAD + BLK_COUNT * DATA_SIZE) / sizeof(int),
                                  MPI_INT, &request));
      MPI_Wait(&request, &status);
  
      /* header and block padding should have no data */
      for (i = 0; i < (HEADER + PAD) / sizeof(int); i++) {
          if (verify[i] != 0) {
              nr_errors++;
              fprintf(stderr, "expected 0, read %d\n", verify[i]);
          }
      }
      /* blocks are replicated */
      for (j = 0; j < BLK_COUNT; j++) {
          for (k = 0; k < (DATA_SIZE / sizeof(int)); k++) {
              if (verify[(HEADER + PAD) / sizeof(int) + k + j * (DATA_SIZE / sizeof(int))]
                  != data[k]) {
                  nr_errors++;
                  fprintf(stderr, "expcted %d, read %d\n", data[k],
                          verify[(HEADER + PAD) / sizeof(int) + k + j * (DATA_SIZE / sizeof(int))]);
              }
              i++;
          }
      }
  
      MPI_File_close(&fh);
  
      MPI_Type_free(&mem_type);
      MPI_Type_free(&file_type);
  
      if (nr_errors == 0)
          printf(" No Errors\n");
  
      MPI_Finalize();
  
      free(data);
      free(verify);
      return 0;
  }
  