compound types on different machines - is this expected?

Howdy HDF5 People!

I have a program called tst_h_wrt_cmp, which write a little array of a
compound type.

Then I have another program called tst_h_rd_cmp.c, which reads them
back in and checks the value. This works on any one machine, but when
I run tst_h_wrt_cmp on a Sun, and try to read the resulting file on a
Linux machine, I get garbled data because the two machines use
different padding for the struct.

Is this expected behavior?

tst_h_wrt_cmp.c:


#include "tests.h"

#define FILE_NAME "tst_h_wrt_cmp.h5"
#define DIM1_LEN 3
#define COMPOUND_NAME "cmp"
#define VAR_NAME "var"

int
main()
{
   hid_t fileid, access_plist, spaceid, typeid;
   hid_t datasetid, datasetid1, typeid1;
   int bool_out[DIM1_LEN] = {0, 1, 0}, bool_in[DIM1_LEN];
   hsize_t dims[1];
   struct s1 {
         unsigned char c1;
         double d;
   } data[DIM1_LEN];
   int i;

   for (i=0; i<DIM1_LEN; i++)
   {
      data[i].c1 = 126;
      data[i].d = -9999999;
   }

   printf("*** Checking packing of HDF5 compound types...");
   
   /* Open file and create group. */
   if ((access_plist = H5Pcreate(H5P_FILE_ACCESS)) < 0) ERR;
   if (H5Pset_fclose_degree(access_plist, H5F_CLOSE_STRONG)) ERR;
   if ((fileid = H5Fcreate(FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, 
                           access_plist)) < 0) ERR;

   /* Create a simple compound type. */
   if ((typeid = H5Tcreate(H5T_COMPOUND, sizeof(struct s1))) < 0) ERR;
   if (H5Tinsert(typeid, "c1", HOFFSET(struct s1, c1), H5T_NATIVE_UCHAR) < 0) 
ERR;
   if (H5Tinsert(typeid, "d", HOFFSET(struct s1, d), H5T_NATIVE_DOUBLE) < 0) 
ERR;
   if (H5Tcommit(fileid, COMPOUND_NAME, typeid) < 0) ERR;

   /* Create a space. */
   dims[0] = DIM1_LEN;
   if ((spaceid = H5Screate_simple(1, dims, dims)) < 0) ERR;

   /* Create a dataset of this compound type. */
   if ((datasetid = H5Dcreate(fileid, VAR_NAME, typeid, spaceid, 
                              H5P_DEFAULT)) < 0) ERR;

   /* Write some data. */
   if (H5Dwrite(datasetid, typeid, H5S_ALL, H5S_ALL, 
                H5P_DEFAULT, data) < 0) ERR;

   /* Release all resources. */
   if (H5Fclose(fileid) < 0) ERR;

   SUMMARIZE_ERR;

   /* Print out our number of errors, if any, and exit badly. */
   if (total_err)
   {
      printf("%d errors detected! Sorry!\n", total_err);
      return 2;
   }
   
   printf("*** Tests successful!\n");
   return 0;
}


tst_h_rd_cmp.c:

#include "tests.h"

#define FILE_NAME "tst_h_wrt_cmp.h5"
#define DIM1_LEN 3
#define COMPOUND_NAME "cmp"
#define VAR_NAME "var"

int
main()
{
   hid_t fileid, access_plist, spaceid, typeid;
   hid_t datasetid, datasetid1, typeid1;
   int bool_out[DIM1_LEN] = {0, 1, 0}, bool_in[DIM1_LEN];
   hsize_t dims[1];
   struct s1 {
         unsigned char c1;
         double d;
   } data[DIM1_LEN];
   int i;

   printf("*** Checking packing of HDF5 compound types...");
   
   /* Open file. */
   if ((access_plist = H5Pcreate(H5P_FILE_ACCESS)) < 0) ERR;
   if (H5Pset_fclose_degree(access_plist, H5F_CLOSE_STRONG)) ERR;
   if ((fileid = H5Fopen(FILE_NAME, H5F_ACC_RDONLY, access_plist)) < 0) ERR;

   /* Open dataset. */
   if ((datasetid = H5Dopen(fileid, VAR_NAME)) < 0) ERR;

   /* Check space. */
   if ((spaceid = H5Dget_space(datasetid)) < 0) ERR;
   if (H5Sget_simple_extent_ndims(spaceid) != 1) ERR;
   if (H5Sget_simple_extent_npoints(spaceid) != DIM1_LEN) ERR;

   /* Get type. */
   if ((typeid = H5Dget_type(datasetid)) < 0) ERR;

   /* Read the data. */
   if (H5Dread(datasetid, typeid, H5S_ALL, H5S_ALL, 
               H5P_DEFAULT, data) < 0) ERR;

   /* Check the data. */
   for (i=0; i<DIM1_LEN; i++)
      if (data[i].c1 != 126 || data[i].d != -9999999) ERR;

   /* Release all resources. */
   if (H5Fclose(fileid) < 0) ERR;

   SUMMARIZE_ERR;

   /* Print out our number of errors, if any, and exit badly. */
   if (total_err)
   {
      printf("%d errors detected! Sorry!\n", total_err);
      return 2;
   }
   
   printf("*** Tests successful!\n");
   return 0;
}

-- 
Ed Hartnett  -- ed@xxxxxxxxxxxxxxxx