[netcdf-hdf] canonical create of HDF5 file

• To: netcdf-hdf@xxxxxxxxxxxxxxxx
• Subject: [netcdf-hdf] canonical create of HDF5 file
• From: Ed Hartnett <ed@xxxxxxxxxxxxxxxx>
• Date: Sun, 13 Jul 2008 07:27:05 -0600

Howdy HDF5 Programmers!

Here's the way that netcdf-4 is creating HDF5 files. Any comments? Is
all the necessary? Is there something missing?


      hid_t fapl_id, fcpl_id, fileid, grpid;

      /* Create file access and create property lists. */
      if ((fapl_id = H5Pcreate(H5P_FILE_ACCESS)) < 0) ERR;
      if ((fcpl_id = H5Pcreate(H5P_FILE_CREATE)) < 0) ERR;
      
      /* Set latest_format in access propertly list. This ensures that
       * the latest, greatest, HDF5 versions are used in the file. */ 
      if (H5Pset_libver_bounds(fapl_id, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 
0) ERR;

      /* Set H5P_CRT_ORDER_TRACKED in the creation property list. This
       * turns on HDF5 creation ordering in the file. */
      if (H5Pset_link_creation_order(fcpl_id, (H5P_CRT_ORDER_TRACKED |
                                               H5P_CRT_ORDER_INDEXED)) < 0) ERR;
      if (H5Pset_attr_creation_order(fcpl_id, (H5P_CRT_ORDER_TRACKED |
                                               H5P_CRT_ORDER_INDEXED)) < 0) ERR;

      /* Create the file. */
      if ((fileid = H5Fcreate(FILE_NAME, H5F_ACC_TRUNC, fcpl_id, fapl_id)) < 0) 
ERR;

      /* Open the root group. */
      if ((grpid = H5Gopen2(fileid, "/", H5P_DEFAULT)) < 0) ERR;

      /* Close up. */
      if (H5Pclose(fapl_id) < 0 ||
          H5Pclose(fcpl_id) < 0 ||
          H5Gclose(grpid) < 0 ||
          H5Fclose(fileid) < 0)
         ERR;


How do I specify the libver_bounds for H5Pset_libver_bounds?

The function accepts a H5F_libver_t. But that is defined as an enum:

/* Library's file format versions */
typedef enum H5F_libver_t {
    H5F_LIBVER_EARLIEST,        /* Use the earliest possible format for storing 
objects */
    H5F_LIBVER_LATEST           /* Use the latest possible format available for 
storing objects*/
} H5F_libver_t;

How then do I specify that I want "1.8.1" to be the value for the
second parameter in the function?

As I read the documentation, if I don't do that, I will be committing
a Microsoftian error. Any time a user upgrades his HDF5 version, and
creates a netCDF-4 file, *all* his users will also have to upgrade
HDF5 to read the file, even if it uses none of the new features
available in that HDF5 release.

We don't want that, do we? So I need to set the first parameter to
1.8.1...

Thanks,

Ed

-- 
Ed Hartnett  -- ed@xxxxxxxxxxxxxxxx

• Follow-Ups:
  • Re: [netcdf-hdf] canonical create of HDF5 file
    • From: Quincey Koziol