path: root/hl/src/H5DS.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group.                                               *
* Copyright by the Board of Trustees of the University of Illinois.         *
* All rights reserved.                                                      *
*                                                                           *
* This file is part of HDF5.  The full HDF5 copyright notice, including     *
* terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "H5DSprivate.h"
#include "H5LTprivate.h"
#include "H5IMprivate.h"
#include "H5TBprivate.h"


/* Local routines */
static herr_t H5DS_is_reserved(hid_t did);
static hid_t H5DS_get_REFLIST_type(void);

/*-------------------------------------------------------------------------
* Function: H5DSset_scale
*
* Purpose: The dataset DSID is converted to a Dimension Scale dataset.
*   Creates the CLASS attribute, set to the value "DIMENSION_SCALE"
*   and an empty REFERENCE_LIST attribute.
*   If DIMNAME is specified, then an attribute called NAME is created,
*   with the value DIMNAME.
*
* Return: Success: SUCCEED, Failure: FAIL
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 04, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

herr_t H5DSset_scale(hid_t dsid,
                     const char *dimname)
{
    int has_dimlist;
    H5I_type_t it;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(dsid)) < 0)
        return FAIL;

    if (H5I_DATASET!=it)
        return FAIL;

    /*-------------------------------------------------------------------------
    * check if the dataset is a dataset wich has references to dimension scales
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "DIMENSION_LIST"  */
    if ((has_dimlist = H5LT_find_attribute(dsid,DIMENSION_LIST)) < 0)
        return FAIL;

    if (has_dimlist == 1)
        return FAIL;

    /*-------------------------------------------------------------------------
    * write the standard attributes for a Dimension Scale dataset
    *-------------------------------------------------------------------------
    */

    if (H5LT_set_attribute_string(dsid,"CLASS",DIMENSION_SCALE_CLASS) < 0)
        return FAIL;

    if (dimname!=NULL)
    {
        if (H5LT_set_attribute_string(dsid,"NAME",dimname) < 0)
            return FAIL;
    }

    return SUCCEED;
}



/*-------------------------------------------------------------------------
* Function: H5DSattach_scale
*
* Purpose: Define Dimension Scale DSID to be associated with dimension IDX
*  of Dataset DID. Entries are created in the DIMENSION_LIST and
*  REFERENCE_LIST attributes.
*
* Return:
*   Success: SUCCEED
*   Failure: FAIL
*
* Fails if: Bad arguments
*           If DSID is not a Dimension Scale
*           If DID is a Dimension Scale (A Dimension Scale cannot have scales)
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: December 20, 2004
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

herr_t H5DSattach_scale(hid_t did,
                        hid_t dsid,
                        unsigned int idx)
{
    int        has_dimlist;
    int        has_reflist;
    int        is_ds;
    hssize_t   nelmts;
    hid_t      sid;          /* space ID */
    hid_t      tid = -1;     /* attribute type ID */
    hid_t      ntid = -1;    /* attribute native type ID */
    hid_t      aid = -1;     /* attribute ID */
    int        rank;         /* rank of dataset */
    hsize_t    dims[1];      /* dimension of the "REFERENCE_LIST" array */
    ds_list_t  dsl;          /* attribute data in the DS pointing to the dataset */
    ds_list_t  *dsbuf = NULL; /* array of attribute data in the DS pointing to the dataset */
    hobj_ref_t ref_to_ds;    /* reference to the DS */
    hobj_ref_t ref_j;        /* iterator reference */
    hvl_t      *buf = NULL;  /* VL buffer to store in the attribute */
    hid_t      dsid_j;       /* DS dataset ID in DIMENSION_LIST */
    H5O_info_t oi1, oi2;
    H5I_type_t it1, it2;
    int        i;
    size_t len;
    int        found_ds=0;
    htri_t     is_scale;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */

    if ((is_scale = H5DSis_scale(did)) < 0)
        return FAIL;

    /* the dataset cannot be a DS dataset */
    if ( is_scale == 1)
        return FAIL;

    /* get info for the dataset in the parameter list */
    if(H5Oget_info2(did, &oi1, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* get info for the scale in the parameter list */
    if(H5Oget_info2(dsid, &oi2, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* same object, not valid */
    if(oi1.fileno == oi2.fileno && oi1.addr == oi2.addr)
        return FAIL;

    /* get ID type */
    if ((it1 = H5Iget_type(did)) < 0)
        return FAIL;
    if ((it2 = H5Iget_type(dsid)) < 0)
        return FAIL;

    if (H5I_DATASET!=it1 || H5I_DATASET!=it2)
        return FAIL;

    /* the DS dataset cannot have dimension scales */
    if (H5LT_find_attribute(dsid,DIMENSION_LIST)==1)
        return FAIL;

    /* check if the dataset is a "reserved" dataset (image, table) */
    if (H5DS_is_reserved(did)==1)
        return FAIL;


    /*-------------------------------------------------------------------------
    * The dataset may or may not have the associated DS attribute
    * First we try to open to see if it is already there; if not, it is created.
    * If it exists, the array of references is extended to hold the reference
    * to the new DS
    *-------------------------------------------------------------------------
    */

    /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank=H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* scalar rank */
    if (rank==0)
        rank=1;

    /* close dataset space */
    if (H5Sclose(sid) < 0)
        return FAIL;

    /* parameter range checking */
    if (idx>(unsigned)rank-1)
        return FAIL;

    /*-------------------------------------------------------------------------
    * two references are created: one to the DS, saved in "DIMENSION_LIST"
    *  and one to the dataset, saved in "REFERENCE_LIST"
    *-------------------------------------------------------------------------
    */
    /* create a reference for the >>DS<< dataset */
    if (H5Rcreate(&ref_to_ds, dsid, ".", H5R_OBJECT, (hid_t)-1) < 0)
        return FAIL;

    /* create a reference for the >>data<< dataset */
    if (H5Rcreate(&dsl.ref, did, ".", H5R_OBJECT, (hid_t)-1) < 0)
        return FAIL;

    /* try to find the attribute "DIMENSION_LIST" on the >>data<< dataset */
    if ((has_dimlist = H5LT_find_attribute(did,DIMENSION_LIST)) < 0)
        return FAIL;

    /*-------------------------------------------------------------------------
    * it does not exist. we create the attribute and its reference data
    *-------------------------------------------------------------------------
    */
    if (has_dimlist == 0)
    {

        dims[0] = (hsize_t)rank;

        /* space for the attribute */
        if((sid = H5Screate_simple(1, dims, NULL)) < 0)
            return FAIL;

        /* create the type for the attribute "DIMENSION_LIST" */
        if((tid = H5Tvlen_create(H5T_STD_REF_OBJ)) < 0)
            goto out;

        /* create the attribute */
        if((aid = H5Acreate2(did, DIMENSION_LIST, tid, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
            goto out;

        /* allocate and initialize the VL */
        buf = (hvl_t *)HDmalloc((size_t)rank * sizeof(hvl_t));
        if(buf == NULL)
            goto out;

        for(i = 0; i < rank; i++) {
            buf[i].len = 0;
            buf[i].p = NULL;
        }

        /* store the REF information in the index of the dataset that has the DS */
        buf[idx].len = 1;
        buf[idx].p = HDmalloc( 1 * sizeof(hobj_ref_t));
        ((hobj_ref_t *)buf[idx].p)[0] = ref_to_ds;

        /* write the attribute with the reference */
        if(H5Awrite(aid, tid, buf) < 0)
            goto out;

        /* close */
        if(H5Treclaim(tid, sid, H5P_DEFAULT, buf) < 0)
            goto out;
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Tclose(tid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;

        HDfree(buf);
        buf = NULL;
    }

    /*-------------------------------------------------------------------------
    * the attribute already exists, open it, extend the buffer,
    *  and insert the new reference
    *-------------------------------------------------------------------------
    */
    else if(has_dimlist == 1)
    {
        if((aid = H5Aopen(did, DIMENSION_LIST, H5P_DEFAULT)) < 0)
            goto out;

        if((tid = H5Aget_type(aid)) < 0)
            goto out;

        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        /* allocate and initialize the VL */
        buf = (hvl_t *)HDmalloc((size_t)rank * sizeof(hvl_t));
        if(buf == NULL)
            goto out;

        /* read */
        if(H5Aread(aid, tid, buf) < 0)
            goto out;

        /* check to avoid inserting duplicates. it is not FAIL, just do nothing */
        /* iterate all the REFs in this dimension IDX */
        for(i = 0; i < (int)buf[idx].len; i++) {
            /* get the reference */
            ref_j = ((hobj_ref_t *)buf[idx].p)[i];

            /* get the scale id for this REF */
            if((dsid_j = H5Rdereference2(did, H5P_DEFAULT, H5R_OBJECT, &ref_j)) < 0)
                goto out;

            /* get info for DS in the parameter list */
            if(H5Oget_info2(dsid, &oi1, H5O_INFO_BASIC) < 0)
                goto out;

            /* get info for this DS */
            if(H5Oget_info2(dsid_j, &oi2, H5O_INFO_BASIC) < 0)
                goto out;

            /* same object, so this DS scale is already in this DIM IDX */
            if(oi1.fileno == oi2.fileno && oi1.addr == oi2.addr)
                found_ds = 1;

            /* close the dereferenced dataset */
            if(H5Dclose(dsid_j) < 0)
                goto out;
        } /* end for */

        if(found_ds == 0) {
            /* we are adding one more DS to this dimension */
            if(buf[idx].len > 0) {
                buf[idx].len++;
                len = buf[idx].len;
                buf[idx].p = HDrealloc(buf[idx].p, len * sizeof(hobj_ref_t));
                ((hobj_ref_t *)buf[idx].p)[len - 1] = ref_to_ds;
            } /* end if */
            else {
                /* store the REF information in the index of the dataset that has the DS */
                buf[idx].len = 1;
                buf[idx].p = HDmalloc(sizeof(hobj_ref_t));
                ((hobj_ref_t *)buf[idx].p)[0] = ref_to_ds;
            } /* end else */
        } /* end if */

        /* write the attribute with the new references */
        if(H5Awrite(aid, tid, buf) < 0)
            goto out;

        /* close */
        if(H5Treclaim(tid, sid, H5P_DEFAULT, buf) < 0)
            goto out;
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Tclose(tid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;
        HDfree(buf);
        buf = NULL;
    } /* has_dimlist */

    /*-------------------------------------------------------------------------
    * save DS info on the >>DS<< dataset
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "REFERENCE_LIST" on the >>DS<< dataset */
    if((has_reflist = H5LT_find_attribute(dsid, REFERENCE_LIST)) < 0)
        goto out;

    /*-------------------------------------------------------------------------
    * it does not exist. we create the attribute and its reference data
    *-------------------------------------------------------------------------
    */
    if(has_reflist == 0) {
        dims[0] = 1;

        /* space for the attribute */
        if((sid = H5Screate_simple(1,dims,NULL)) < 0)
            goto out;

        /* create the compound datatype for the attribute "REFERENCE_LIST" */
        if((tid = H5Tcreate(H5T_COMPOUND, sizeof(ds_list_t))) < 0)
            goto out;

        /* insert reference field */
        if(H5Tinsert(tid, "dataset", HOFFSET(ds_list_t,ref), H5T_STD_REF_OBJ) < 0)
            goto out;

        /* insert dimension idx of the dataset field */
        if(H5Tinsert(tid, "dimension", HOFFSET(ds_list_t, dim_idx), H5T_NATIVE_INT) < 0)
            goto out;

        /* create the attribute */
        if((aid = H5Acreate2(dsid, REFERENCE_LIST, tid, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
            goto out;

        /* store the IDX information */
        dsl.dim_idx = idx;

        /* write the attribute with the reference */
        if(H5Awrite(aid, tid, &dsl) < 0)
            goto out;

        /* close */
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Tclose(tid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;
    } /* end if */

    /*-------------------------------------------------------------------------
    * the "REFERENCE_LIST" array already exists, open it and extend it
    *-------------------------------------------------------------------------
    */
    else if(has_reflist ==  1) {
        if((aid = H5Aopen(dsid, REFERENCE_LIST, H5P_DEFAULT)) < 0)
            goto out;

        if((tid = H5Aget_type(aid)) < 0)
            goto out;

        /* get native type to read attribute REFERENCE_LIST */
        if((ntid = H5DS_get_REFLIST_type()) < 0)
            goto out;

        /* get and save the old reference(s) */
        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        if((nelmts = H5Sget_simple_extent_npoints(sid)) < 0)
            goto out;

        nelmts++;

        dsbuf = (ds_list_t*) HDmalloc((size_t)nelmts * sizeof(ds_list_t));
        if(dsbuf == NULL)
            goto out;

        if(H5Aread(aid, ntid, dsbuf) < 0)
            goto out;

        /* close */
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;

        /*-------------------------------------------------------------------------
        * create a new attribute
        *-------------------------------------------------------------------------
        */

        /* the attribute must be deleted, in order to the new one can reflect the changes*/
        if(H5Adelete(dsid, REFERENCE_LIST) < 0)
            goto out;

        /* store the IDX information (index of the dataset that has the DS) */
        dsl.dim_idx = idx;
        dsbuf[nelmts - 1] = dsl;

        /* create a new data space for the new references array */
        dims[0] = (hsize_t)nelmts;

        if((sid = H5Screate_simple(1, dims, NULL)) < 0)
            goto out;

        /* create the attribute again with the changes of space */
        if((aid = H5Acreate2(dsid, REFERENCE_LIST, tid, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
            goto out;

        /* write the attribute with the new references */
        if(H5Awrite(aid, ntid, dsbuf) < 0)
            goto out;

        /* close */
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Tclose(tid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;
        if (H5Tclose(ntid) < 0)
            goto out;

        HDfree(dsbuf);
        dsbuf = NULL;
    } /* has_reflist */

    /*-------------------------------------------------------------------------
    * write the standard attributes for a Dimension Scale dataset
    *-------------------------------------------------------------------------
    */

    if((is_ds=H5DSis_scale(dsid)) < 0)
        return FAIL;

    if(is_ds == 0) {
        if (H5LT_set_attribute_string(dsid,"CLASS",DIMENSION_SCALE_CLASS) < 0)
            return FAIL;
    }

    return SUCCEED;

    /* error zone */
out:
    if(buf)
        HDfree(buf);
    if(dsbuf)
        HDfree(dsbuf);

    H5E_BEGIN_TRY {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(ntid);
        H5Tclose(tid);
    } H5E_END_TRY;
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSdetach_scale
*
* Purpose: If possible, deletes association of Dimension Scale DSID with
*     dimension IDX of Dataset DID. This deletes the entries in the
*     DIMENSION_LIST and REFERENCE_LIST attributes.
*
* Return:
*   Success: SUCCEED
*   Failure: FAIL
*
* Fails if: Bad arguments
*           The dataset DID or DSID do not exist.
*           The DSID is not a Dimension Scale
*           DSID is not attached to DID.
* Note that a scale may be associated with more than dimension of the same dataset.
* If so, the detach operation only deletes one of the associations, for DID.
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: December 20, 2004
*
* Comments:
*
* Modifications: Function didn't delete DIMENSION_LIST attribute, when
*                all dimension scales were detached from a dataset; added.
*                                                           2010/05/13 EIP
*
*-------------------------------------------------------------------------
*/

herr_t H5DSdetach_scale(hid_t did,
                        hid_t dsid,
                        unsigned int idx)
{
    int        has_dimlist;
    int        has_reflist;
    hssize_t   nelmts;
    hid_t      dsid_j;       /* DS dataset ID in DIMENSION_LIST */
    hid_t      did_i;        /* dataset ID in REFERENCE_LIST */
    hid_t      sid;          /* space ID */
    hid_t      tid = -1;     /* attribute type ID */
    hid_t      ntid = -1;    /* attribute native type ID */
    hid_t      aid = -1;     /* attribute ID */
    int        rank;         /* rank of dataset */
    ds_list_t  *dsbuf = NULL;  /* array of attribute data in the DS pointing to the dataset */
    hsize_t    dims[1];      /* dimension of the "REFERENCE_LIST" array */
    hobj_ref_t ref;          /* reference to the DS */
    hvl_t      *buf = NULL;  /* VL buffer to store in the attribute */
    int        i;
    size_t     j;
    hssize_t   ii;
    H5O_info_t did_oi, dsid_oi, tmp_oi;
    int        found_dset = 0, found_ds = 0;
    int        have_ds = 0;
    htri_t     is_scale;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */

    /* check for valid types of identifiers */

    if(H5I_DATASET!=H5Iget_type(did) || H5I_DATASET!=H5Iget_type(dsid))
        return FAIL;

    if((is_scale = H5DSis_scale(did)) < 0)
        return FAIL;

    /* the dataset cannot be a DS dataset */
    if( is_scale == 1)
        return FAIL;

    /* get info for the dataset in the parameter list */
    if(H5Oget_info2(did, &did_oi, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* get info for the scale in the parameter list */
    if(H5Oget_info2(dsid, &dsid_oi, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* same object, not valid */
    if(did_oi.fileno == dsid_oi.fileno && did_oi.addr == dsid_oi.addr)
        return FAIL;


    /*-------------------------------------------------------------------------
    * Find "DIMENSION_LIST"
    *-------------------------------------------------------------------------
    */
    /* try to find the attribute "DIMENSION_LIST" on the >>data<< dataset */
    if ((has_dimlist = H5LT_find_attribute(did,DIMENSION_LIST)) < 0)
        return FAIL;

    if (has_dimlist == 0)
        return FAIL;

    /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank=H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if (H5Sclose(sid) < 0)
        return FAIL;

    /* parameter range checking */
    if (idx>(unsigned)rank-1)
        return FAIL;

    /*-------------------------------------------------------------------------
    * find "REFERENCE_LIST"
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "REFERENCE_LIST" on the >>DS<< dataset */
    if((has_reflist = H5LT_find_attribute(dsid, REFERENCE_LIST)) < 0)
        return FAIL;

    if(has_reflist == 0)
        return FAIL;

    /*-------------------------------------------------------------------------
    * open "DIMENSION_LIST", and delete the reference
    *-------------------------------------------------------------------------
    */

    if((aid = H5Aopen(did, DIMENSION_LIST, H5P_DEFAULT)) < 0)
        return FAIL;

    if((tid = H5Aget_type(aid)) < 0)
        goto out;

    if((sid = H5Aget_space(aid)) < 0)
        goto out;

    /* allocate and initialize the VL */
    buf = (hvl_t *)HDmalloc((size_t)rank * sizeof(hvl_t));
    if(buf == NULL)
        goto out;

    /* read */
    if(H5Aread(aid, tid, buf) < 0)
        goto out;

    /* reset */
    if ( buf[idx].len > 0 )
    {
        for (j=0; j<buf[idx].len; j++)
        {
            /* get the reference */
            ref = ((hobj_ref_t *)buf[idx].p)[j];

            /* get the DS id */
            if ((dsid_j = H5Rdereference2(did,H5P_DEFAULT,H5R_OBJECT,&ref)) < 0)
                goto out;

            /* get info for this DS */
            if(H5Oget_info2(dsid_j, &tmp_oi, H5O_INFO_BASIC) < 0)
                goto out;

            /* Close the dereferenced dataset */
            if (H5Dclose(dsid_j) < 0)
                goto out;

            /* same object, reset */
            if(dsid_oi.fileno == tmp_oi.fileno && dsid_oi.addr == tmp_oi.addr)
            {
                /* If there are more than one reference in the VL element
                   and the reference we found is not the last one,
                   copy the last one to replace the found one since the order
                   of the references doesn't matter according to the spec;
                   reduce the size of the VL element by 1;
                   if the length of the element becomes 0, free the pointer
                   and reset to NULL */

                size_t len = buf[idx].len;

                if(j < len - 1)
                    ((hobj_ref_t *)buf[idx].p)[j] = ((hobj_ref_t *)buf[idx].p)[len-1];
                len = --buf[idx].len;
                if(len == 0) {
                    HDfree(buf[idx].p);
                    buf[idx].p = NULL;
                }
                /* Since a reference to a dim. scale can be inserted only once,
                   we do not need to continue the search if it is found */
                found_ds = 1;
                break;
            }
        } /* j */
    } /* if */

    /* the scale must be present to continue */
    if(found_ds == 0)
        goto out;

    /* Write the attribute, but check first, if we have any scales left,
       because if not, we should delete the attribute according to the spec */
    for(i = 0; i < rank; i++) {
        if(buf[i].len > 0)  {
            have_ds = 1;
            break;
        }
    }
    if(have_ds) {
        if(H5Awrite(aid, tid, buf) < 0)
            goto out;
    }
    else {
        if(H5Adelete(did, DIMENSION_LIST) < 0)
            goto out;
    }

    /* close */
    if(H5Treclaim(tid, sid, H5P_DEFAULT, buf) < 0)
        goto out;
    if(H5Sclose(sid) < 0)
        goto out;
    if(H5Tclose(tid) < 0)
        goto out;
    if(H5Aclose(aid) < 0)
        goto out;

    HDfree(buf);
    buf = NULL;


    /*-------------------------------------------------------------------------
    * the "REFERENCE_LIST" array exists, update
    *-------------------------------------------------------------------------
    */

    if((aid = H5Aopen(dsid, REFERENCE_LIST, H5P_DEFAULT)) < 0)
        goto out;

    if((tid = H5Aget_type(aid)) < 0)
        goto out;

    /* get native type to read attribute REFERENCE_LIST */
    if((ntid = H5DS_get_REFLIST_type()) < 0)
        goto out;

    /* get and save the old reference(s) */
    if((sid = H5Aget_space(aid)) < 0)
        goto out;

    if((nelmts = H5Sget_simple_extent_npoints(sid)) < 0)
        goto out;

    dsbuf = (ds_list_t*) HDmalloc((size_t)nelmts * sizeof(ds_list_t));
    if(dsbuf == NULL)
        goto out;

    if(H5Aread(aid, ntid, dsbuf) < 0)
        goto out;

    for(ii=0; ii<nelmts; ii++) {
        /* First check if we have the same dimension index */
      if(idx == dsbuf[ii].dim_idx) {
            /* get the reference to the dataset */
            ref = dsbuf[ii].ref;

            /* get the dataset id */
            if ((did_i = H5Rdereference2(did,H5P_DEFAULT,H5R_OBJECT,&ref)) < 0)
                goto out;

            /* get info for this dataset */
            if(H5Oget_info2(did_i, &tmp_oi, H5O_INFO_BASIC) < 0)
                goto out;

            /* close the dereferenced dataset */
            if(H5Dclose(did_i) < 0)
                goto out;

            /* same object, reset. we want to detach only for this DIM */
            if(did_oi.fileno == tmp_oi.fileno && did_oi.addr == tmp_oi.addr) {
                /* copy the last one to replace the one which is found */
                dsbuf[ii] = dsbuf[nelmts-1];
                nelmts--;
                found_dset=1;
                break;
            } /* if */
        } /* if we have the same dimension index */
    } /* ii */

    /* close space and attribute */
    if (H5Sclose(sid) < 0)
        goto out;
    if (H5Aclose(aid) < 0)
        goto out;

    /*-------------------------------------------------------------------------
    * check if we found the pointed dataset
    *-------------------------------------------------------------------------
    */

    /* the pointed dataset must exist */
    if (found_dset == 0)
        goto out;

    /*-------------------------------------------------------------------------
    * create a new attribute
    *-------------------------------------------------------------------------
    */

    /* the attribute must be deleted, in order to the new one can reflect the changes*/
    if (H5Adelete(dsid, REFERENCE_LIST) < 0)
        goto out;

    /* don't do anything for an empty array */
    if(nelmts)
    {
        /* create a new data space for the new references array */
      dims[0] = (hsize_t)nelmts;

        if((sid = H5Screate_simple(1, dims, NULL)) < 0)
            goto out;

        /* create the attribute again with the changes of space */
        if((aid = H5Acreate2(dsid, REFERENCE_LIST, tid, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
            goto out;

        /* write the new attribute with the new references */
        if(H5Awrite(aid, ntid, dsbuf) < 0)
            goto out;

        /* close space and attribute */
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;
    } /* nelmts */

    /* close type */
    if (H5Tclose(tid) < 0)
        goto out;
    if (H5Tclose(ntid) < 0)
        goto out;

    HDfree(dsbuf);
    dsbuf = NULL;

    return SUCCEED;

    /* error zone */
out:
    H5E_BEGIN_TRY {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(ntid);
        H5Tclose(tid);

        if(dsbuf) {
            HDfree(dsbuf);
            dsbuf = NULL;
        }
        if(buf) {
            /* Failure occured before H5Treclaim was called;
               free the pointers allocated when we read data in */
            for(i = 0; i < rank; i++) {
                if(buf[i].p)
                    HDfree(buf[i].p);
            }
            HDfree(buf);
            buf = NULL;
        }
    } H5E_END_TRY;
    return FAIL;

}

/*-------------------------------------------------------------------------
* Function: H5DSis_attached
*
* Purpose: Report if dimension scale DSID is currently attached to
*  dimension IDX of dataset DID by checking if DID has a pointer in the REFERENCE_LIST
*  attribute and DSID (scale ) has a pointer in the DIMENSION_LIST attribute
*
* Return:
*   1: both the DS and the dataset pointers match
*   0: one of them or both do not match
*   FAIL (-1): error
*
* Fails if: Bad arguments
*           If DSID is not a Dimension Scale
*           If DID is a Dimension Scale (A Dimension Scale cannot have scales)
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: February 18, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

htri_t H5DSis_attached(hid_t did,
                       hid_t dsid,
                       unsigned int idx)
{
    int        has_dimlist;
    int        has_reflist;
    hssize_t   nelmts;
    hid_t      sid;          /* space ID */
    hid_t      tid = -1;     /* attribute type ID */
    hid_t      ntid = -1;    /* attribute native type ID */
    hid_t      aid = -1;     /* attribute ID */
    int        rank;         /* rank of dataset */
    ds_list_t  *dsbuf = NULL;   /* array of attribute data in the DS pointing to the dataset */
    hobj_ref_t ref;          /* reference to the DS */
    hvl_t      *buf = NULL;  /* VL buffer to store in the attribute */
    hid_t      dsid_j;       /* DS dataset ID in DIMENSION_LIST */
    hid_t      did_i;        /* dataset ID in REFERENCE_LIST */
    H5O_info_t oi1, oi2, oi3, oi4;
    H5I_type_t it1, it2;
    int        i;
    int        found_dset=0, found_ds=0;
    htri_t     is_scale;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */

    if ((is_scale = H5DSis_scale(did)) < 0)
        return FAIL;

    /* the dataset cannot be a DS dataset */
    if ( is_scale == 1)
        return FAIL;

    /* get info for the dataset in the parameter list */
    if(H5Oget_info2(did, &oi1, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* get info for the scale in the parameter list */
    if(H5Oget_info2(dsid, &oi2, H5O_INFO_BASIC) < 0)
        return FAIL;

    /* same object, not valid */
    if(oi1.fileno == oi2.fileno && oi1.addr == oi2.addr)
        return FAIL;

    /* get ID type */
    if ((it1 = H5Iget_type(did)) < 0)
        return FAIL;
    if ((it2 = H5Iget_type(dsid)) < 0)
        return FAIL;

    if (H5I_DATASET!=it1 || H5I_DATASET!=it2)
        return FAIL;

    /*-------------------------------------------------------------------------
    * get space
    *-------------------------------------------------------------------------
    */

    /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank=H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if (H5Sclose(sid) < 0)
        goto out;

    /* parameter range checking */
    if(idx > ((unsigned)rank - 1))
        return FAIL;

    /* try to find the attribute "DIMENSION_LIST" on the >>data<< dataset */
    if((has_dimlist = H5LT_find_attribute(did, DIMENSION_LIST)) < 0)
        return FAIL;

    /*-------------------------------------------------------------------------
    * open "DIMENSION_LIST"
    *-------------------------------------------------------------------------
    */

    if(has_dimlist == 1)
    {
        if((aid = H5Aopen(did, DIMENSION_LIST, H5P_DEFAULT)) < 0)
            goto out;

        if((tid = H5Aget_type(aid)) < 0)
            goto out;

        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        /* allocate and initialize the VL */
        buf = (hvl_t*)HDmalloc((size_t)rank * sizeof(hvl_t));
        if(buf == NULL)
            goto out;

        /* read */
        if (H5Aread(aid,tid,buf) < 0)
            goto out;

        /* iterate all the REFs in this dimension IDX */
        for (i=0; i<(int)buf[idx].len; i++)
        {
            /* get the reference */
            ref = ((hobj_ref_t *)buf[idx].p)[i];

            /* get the scale id for this REF */
            if ((dsid_j = H5Rdereference2(did,H5P_DEFAULT,H5R_OBJECT,&ref)) < 0)
                goto out;

            /* get info for DS in the parameter list */
            if(H5Oget_info2(dsid, &oi1, H5O_INFO_BASIC) < 0)
                goto out;

            /* get info for this DS */
            if(H5Oget_info2(dsid_j, &oi2, H5O_INFO_BASIC) < 0)
                goto out;

            /* same object */
            if(oi1.fileno == oi2.fileno && oi1.addr == oi2.addr)
                found_ds = 1;

            /* close the dereferenced dataset */
            if (H5Dclose(dsid_j) < 0)
                goto out;

        }


        /* close */
        if (H5Treclaim(tid,sid,H5P_DEFAULT,buf) < 0)
            goto out;
        if (H5Sclose(sid) < 0)
            goto out;
        if (H5Tclose(tid) < 0)
            goto out;
        if (H5Aclose(aid) < 0)
            goto out;
        HDfree(buf);
        buf = NULL;
    } /* has_dimlist */

    /*-------------------------------------------------------------------------
    * info on the >>DS<< dataset
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "REFERENCE_LIST" on the >>DS<< dataset */
    if((has_reflist = H5LT_find_attribute(dsid, REFERENCE_LIST)) < 0)
        goto out;

    /*-------------------------------------------------------------------------
    * open "REFERENCE_LIST"
    *-------------------------------------------------------------------------
    */

    if(has_reflist ==  1)
    {
        if((aid = H5Aopen(dsid, REFERENCE_LIST, H5P_DEFAULT)) < 0)
            goto out;

        if((tid = H5Aget_type(aid)) < 0)
            goto out;

        /* get native type to read REFERENCE_LIST attribute */
        if((ntid = H5DS_get_REFLIST_type()) < 0)
            goto out;

        /* get and save the old reference(s) */
        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        if((nelmts = H5Sget_simple_extent_npoints(sid)) < 0)
            goto out;

        dsbuf = (ds_list_t*) HDmalloc((size_t)nelmts * sizeof(ds_list_t));

        if (dsbuf == NULL)
            goto out;

        if (H5Aread(aid,ntid,dsbuf) < 0)
            goto out;

        /*-------------------------------------------------------------------------
        * iterate
        *-------------------------------------------------------------------------
        */

        for(i=0; i<nelmts; i++)
        {
            /* get the reference */
            ref = dsbuf[i].ref;

            /* the reference was not deleted  */
            if (ref)
            {
                /* get the dataset id */
                if ((did_i = H5Rdereference2(did,H5P_DEFAULT,H5R_OBJECT,&ref)) < 0)
                    goto out;

                /* get info for dataset in the parameter list */
                if(H5Oget_info2(did, &oi3, H5O_INFO_BASIC) < 0)
                    goto out;

                /* get info for this dataset */
                if(H5Oget_info2(did_i, &oi4, H5O_INFO_BASIC) < 0)
                    goto out;

                /* same object */
                if(oi3.fileno == oi4.fileno && oi3.addr == oi4.addr && idx==dsbuf[i].dim_idx)
                    found_dset=1;

                /* close the dereferenced dataset */
                if (H5Dclose(did_i) < 0)
                    goto out;
            } /* if */
        } /* i */


        /* close */
        if (H5Sclose(sid) < 0)
            goto out;
        if (H5Tclose(ntid) < 0)
            goto out;
        if (H5Tclose(tid) < 0)
            goto out;
        if (H5Aclose(aid) < 0)
            goto out;

        HDfree(dsbuf);
        dsbuf = NULL;
    } /* has_reflist */

    if (found_ds && found_dset)
        return 1;
    else
        return 0;

    /* error zone */
out:
    H5E_BEGIN_TRY {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(tid);
        H5Tclose(ntid);
    } H5E_END_TRY;

    if (buf) {
        HDfree(buf);
        buf = NULL;
    }
    if(dsbuf) {
        HDfree(dsbuf);
        dsbuf = NULL;
    }
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSiterate_scales
*
* Purpose: H5DSiterate_scales iterates over the scales attached to dimension DIM
*  of dataset DID. For each scale in the list, the visitor_data and some
*  additional information, specified below, are passed to the visitor function.
*  The iteration begins with the IDX object in the group and the next element
*  to be processed by the operator is returned in IDX. If IDX is NULL, then the
*  iterator starts at zero.
*
* Parameters:
*
*  hid_t DID;               IN: the dataset
*  unsigned int DIM;        IN: the dimension of the dataset
*  int *DS_IDX;             IN/OUT: on input the dimension scale index to start iterating,
*                               on output the next index to visit. If NULL, start at
*                               the first position.
*  H5DS_iterate_t VISITOR;  IN: the visitor function
*  void *VISITOR_DATA;      IN: arbitrary data to pass to the visitor function.
*
*  Iterate over all scales of DIM, calling an application callback
*   with the item, key and any operator data.
*
*   The operator callback receives a pointer to the item ,
*   and the pointer to the operator data passed
*   in to H5SL_iterate ('op_data').  The return values from an operator are:
*       A. Zero causes the iterator to continue, returning zero when all
*           nodes of that type have been processed.
*       B. Positive causes the iterator to immediately return that positive
*           value, indicating short-circuit success.
*       C. Negative causes the iterator to immediately return that value,
*           indicating failure.
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 31, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

herr_t H5DSiterate_scales(hid_t did,
                          unsigned int dim,
                          int *ds_idx,
                          H5DS_iterate_t visitor,
                          void *visitor_data )
{
    hid_t        scale_id;
    int          rank;
    hobj_ref_t   ref;          /* reference to the DS */
    hid_t        sid;          /* space ID */
    hid_t        tid = -1;     /* attribute type ID */
    hid_t        aid = -1;     /* attribute ID */
    hvl_t        *buf = NULL;    /* VL buffer to store in the attribute */
    H5I_type_t   it;           /* ID type */
    herr_t       ret_value=0;
    int          j_idx;
    int          nscales;
    int          has_dimlist;
    int          i;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(did)) < 0)
        return FAIL;

    if (H5I_DATASET!=it)
        return FAIL;

    /* get the number of scales assotiated with this DIM */
    if ((nscales = H5DSget_num_scales(did,dim)) < 0)
        return FAIL;

    /* parameter range checking */
    if (ds_idx!=NULL)
    {
        if (*ds_idx>=nscales)
            return FAIL;
    }

    /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank=H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if(H5Sclose(sid) < 0)
        goto out;

    if ( dim >= (unsigned)rank )
        return FAIL;

    /* try to find the attribute "DIMENSION_LIST" on the >>data<< dataset */
    if((has_dimlist = H5LT_find_attribute(did, DIMENSION_LIST)) < 0)
        return FAIL;

    if(has_dimlist == 0)
        return SUCCEED;

    else if(has_dimlist == 1)
    {
        if((aid = H5Aopen(did, DIMENSION_LIST, H5P_DEFAULT)) < 0)
            goto out;
        if((tid = H5Aget_type(aid)) < 0)
            goto out;
        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        /* allocate and initialize the VL */
        buf = (hvl_t*)HDmalloc((size_t)rank * sizeof(hvl_t));

        if(buf == NULL)
            goto out;

        /* read */
        if(H5Aread(aid, tid, buf) < 0)
            goto out;

        if ( buf[dim].len > 0 )
        {
            if (ds_idx!=NULL)
                j_idx = *ds_idx;
            else
                j_idx=0;

            /* iterate */
            for(i=j_idx; i<nscales; i++)
            {
                /* get the reference */
                ref = ((hobj_ref_t *)buf[dim].p)[ i ];

                /* disable error reporting, the ID might refer to a deleted dataset */
                H5E_BEGIN_TRY {
                    /* get the DS id */
                    if ((scale_id = H5Rdereference2(did,H5P_DEFAULT,H5R_OBJECT,&ref)) < 0)
                        goto out;
                } H5E_END_TRY;

                /* set the return IDX OUT value at current scale index */
                if (ds_idx!=NULL)
                {
                    *ds_idx = i;
                }

                if((ret_value=(visitor)(did,dim,scale_id,visitor_data))!=0)
                {
                    /* break */

                    /* close the DS id */
                    if (H5Dclose(scale_id) < 0)
                        goto out;

                    break;
                }

                /* close the DS id */
                if (H5Dclose(scale_id) < 0)
                    goto out;

            } /* i */
        } /* if */

        /* close */
        if (H5Treclaim(tid,sid,H5P_DEFAULT,buf) < 0)
            goto out;
        if (H5Sclose(sid) < 0)
            goto out;
        if (H5Tclose(tid) < 0)
            goto out;
        if (H5Aclose(aid) < 0)
            goto out;

        HDfree(buf);
        buf = NULL;
    } /* if has_dimlist */

    return ret_value;

out:
    H5E_BEGIN_TRY {
        if(buf) {
            H5Treclaim(tid,sid,H5P_DEFAULT,buf);
            HDfree(buf);
        }
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(tid);
    } H5E_END_TRY;

    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSset_label
*
* Purpose: Set label for the dimension IDX of dataset DID to the value LABEL
*
* Return: Success: SUCCEED, Failure: FAIL
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 11, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

herr_t H5DSset_label(hid_t did, unsigned int idx, const char *label)
{
    int        has_labels;
    hid_t      sid = -1;      /* space ID */
    hid_t      tid = -1;      /* attribute type ID */
    hid_t      aid = -1;      /* attribute ID */
    int        rank;          /* rank of dataset */
    hsize_t    dims[1];       /* dimensions of dataset */
    H5I_type_t it;            /* ID type */
    unsigned   int i;
    union {                    /* union is needed to eliminate compiler warnings about */
      char  ** buf;            /* discarding the 'const' qualifier in the free */
      char const ** const_buf; /* buf calls */
    } u;
    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(did)) < 0)
        return FAIL;

    if (H5I_DATASET != it)
        return FAIL;

    if (label == NULL)
        return FAIL;

     /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank = H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if (H5Sclose(sid) < 0)
        goto out;

    if ( idx >= (unsigned)rank )
        return FAIL;

    /*-------------------------------------------------------------------------
    * attribute "DIMENSION_LABELS"
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "DIMENSION_LABELS" on the >>data<< dataset */
    if ((has_labels = H5LT_find_attribute(did, DIMENSION_LABELS)) < 0)
        return FAIL;

    /*-------------------------------------------------------------------------
    * make the attribute and insert label
    *-------------------------------------------------------------------------
    */

    if (has_labels == 0)
    {
        dims[0] = (hsize_t)rank;

        /* space for the attribute */
        if ((sid = H5Screate_simple(1, dims, NULL)) < 0)
            goto out;

        /* create the datatype  */
        if ((tid = H5Tcopy(H5T_C_S1)) < 0)
            goto out;
        if (H5Tset_size(tid, H5T_VARIABLE) < 0)
            goto out;

        /* create the attribute */
        if ((aid = H5Acreate2(did, DIMENSION_LABELS, tid, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
            goto out;

        /* allocate and initialize */
        u.const_buf = (char const **) HDmalloc((size_t) rank * sizeof(char *));

        if (u.const_buf == NULL)
            goto out;

        for (i = 0; i < (unsigned int) rank; i++)
            u.const_buf[i] = NULL;

        /* store the label information in the required index */
        u.const_buf[idx] = label;

        /* write the attribute with the label */
        if (H5Awrite(aid, tid, u.const_buf) < 0)
            goto out;

        /* close */
        if (H5Sclose(sid) < 0)
            goto out;
        if (H5Tclose(tid) < 0)
            goto out;
        if (H5Aclose(aid) < 0)
            goto out;
        if (u.const_buf)
        {
            HDfree(u.const_buf);
            u.const_buf = NULL;
        }
    }

    /*-------------------------------------------------------------------------
    * just insert label
    *-------------------------------------------------------------------------
    */

    else
    {

        if ((aid = H5Aopen(did, DIMENSION_LABELS, H5P_DEFAULT)) < 0)
            goto out;

        if ((tid = H5Aget_type(aid)) < 0)
            goto out;

        /* allocate and initialize */
        u.buf = (char **) HDmalloc((size_t) rank * sizeof(char *));

        if (u.buf == NULL)
            goto out;

        /* read */
        if (H5Aread(aid, tid, (void *)u.buf) < 0)
            goto out;

        /* free the ptr that will be replaced by label */
        if (u.buf[idx])
            HDfree(u.buf[idx]);

        /* store the label information in the required index */
        u.const_buf[idx] = label;

        /* write the attribute with the new references */
        if (H5Awrite(aid, tid, u.buf) < 0)
            goto out;

        /* label was brought in, so don't free */
        u.buf[idx] = NULL;

        /* free all the ptr's from the H5Aread() */
        for (i = 0; i < (unsigned int) rank; i++)
        {
            if (u.buf[i])
                HDfree(u.buf[i]);
        }

        /* close */
        if (H5Tclose(tid) < 0)
            goto out;
        if (H5Aclose(aid) < 0)
            goto out;
        if (u.buf)
        {
            HDfree(u.buf);
            u.buf = NULL;
        }
    }

    return SUCCEED;

    /* error zone */

out:
    if (u.buf)
    {
        if (u.buf[idx]) /* check if we errored during H5Awrite */
            u.buf[idx] = NULL; /* don't free label */
        /* free all the ptr's from the H5Aread() */
        for (i = 0; i < (unsigned int) rank; i++)
        {
            if (u.buf[i])
                HDfree(u.buf[i]);
        }
        HDfree(u.buf);
    }
    H5E_BEGIN_TRY
    {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(tid);
    }H5E_END_TRY;
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSget_label
*
* Purpose: Read the label LABEL for dimension IDX of dataset DID
*   Up to 'size' characters are stored in 'label' followed by a '\0' string
*   terminator.  If the label is longer than 'size'-1,
*   the string terminator is stored in the last position of the buffer to
*   properly terminate the string.
*
* Return: 0 if no label found, size of label if found, Failure: FAIL
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 11, 2005
*
* Comments:
*
* Modifications:
*     JIRA HDFFV-7673: Added a check to see if the label name exists,
*     if not then returns zero. July 30, 2011. MSB
*
*-------------------------------------------------------------------------
*/
ssize_t H5DSget_label(hid_t did, unsigned int idx, char *label, size_t size)
{
    int        has_labels;
    hid_t      sid = -1;     /* space ID */
    hid_t      tid = -1;     /* attribute type ID */
    hid_t      aid = -1;     /* attribute ID */
    int        rank;         /* rank of dataset */
    char       **buf = NULL; /* buffer to store in the attribute */
    H5I_type_t it;           /* ID type */
    size_t     nbytes = 0;
    size_t     copy_len;
    int        i;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(did)) < 0)
        return FAIL;

    if (H5I_DATASET != it)
        return FAIL;

     /* get dataset space */
    if ((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if ((rank = H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if (H5Sclose(sid) < 0)
        goto out;

    if ( idx >= (unsigned)rank )
        return FAIL;

    /*-------------------------------------------------------------------------
    * attribute "DIMENSION_LABELS"
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "DIMENSION_LABELS" on the >>data<< dataset */
    if ((has_labels = H5LT_find_attribute(did, DIMENSION_LABELS)) < 0)
        return FAIL;

    /* return 0 and NULL for label if no label found */
    if (has_labels == 0)
    {
        if (label)
            label[0] = 0;
        return 0;
    }

    /*-------------------------------------------------------------------------
    * open the attribute and read label
    *-------------------------------------------------------------------------
    */

    assert (has_labels == 1);
    if ((aid = H5Aopen(did, DIMENSION_LABELS, H5P_DEFAULT)) < 0)
        goto out;


    if ((tid = H5Aget_type(aid)) < 0)
        goto out;

    /* allocate and initialize */
    buf = (char **) HDmalloc((size_t) rank * sizeof(char *));

    if (buf == NULL)
        goto out;

    /* read */
    if (H5Aread(aid, tid, buf) < 0)
        goto out;

    /* do only if the label name exists for the dimension */
    if (buf[idx] != NULL)
    {
        /* get the real string length */
        nbytes = HDstrlen(buf[idx]);

        /* compute the string length which will fit into the user's buffer */
        copy_len = MIN(size-1, nbytes);

        /* copy all/some of the name */
        if (label)
        {
            HDmemcpy(label, buf[idx], copy_len);

            /* terminate the string */
            label[copy_len] = '\0';
        }

    }
    /* free all the ptr's from the H5Aread() */
    for (i = 0; i < rank; i++)
    {
        if (buf[i])
            HDfree(buf[i]);
    }

    /* close */
    if (H5Tclose(tid) < 0)
        goto out;
    if (H5Aclose(aid) < 0)
        goto out;
    if (buf)
    {
        HDfree(buf);
        buf = NULL;
    }

    return (ssize_t) nbytes;

    /* error zone */
out:
    if (buf)
    {
        /* free all the ptr's from the H5Aread() */
        for (i = 0; i < rank; i++)
        {
            if (buf[i])
                HDfree(buf[i]);
        }
        HDfree(buf);
    }
    H5E_BEGIN_TRY
    {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(tid);
    }H5E_END_TRY;
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSget_scale_name
*
* Purpose: Read the name of dataset scale DID into buffer NAME
*   Up to 'size' characters are stored in 'name' followed by a '\0' string
*   terminator.  If the name is longer than 'size'-1,
*   the string terminator is stored in the last position of the buffer to
*   properly terminate the string.
*
* Return: size of name if found, zero if not found,  Failure: FAIL
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 04, 2005
*
* Comments:
*
* Modifications:
*  The size of the name returned should not include the NULL termination
*  in its value so as to be consistent with other HDF5 APIs.
*
*-------------------------------------------------------------------------
*/

ssize_t H5DSget_scale_name(hid_t did,
                           char *name,
                           size_t size)
{
    hid_t      aid;      /* attribute ID  */
    hid_t      tid = -1; /* attribute type ID */
    hid_t      sid;      /* space ID  */
    H5I_type_t it;       /* ID type */
    size_t     nbytes;
    size_t     copy_len;
    int        has_name;
    char       *buf=NULL;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(did)) < 0)
        return FAIL;

    if (H5I_DATASET!=it)
        return FAIL;

    if ((H5DSis_scale(did))<=0)
        return FAIL;

    /*-------------------------------------------------------------------------
    * check if the DS has a name
    *-------------------------------------------------------------------------
    */

    /* try to find the attribute "NAME" on the >>DS<< dataset */
    if ((has_name = H5LT_find_attribute(did, "NAME")) < 0)
        return FAIL;

    if (has_name == 0)
        return 0;

    /*-------------------------------------------------------------------------
    * open the attribute
    *-------------------------------------------------------------------------
    */

    if((aid = H5Aopen(did, "NAME", H5P_DEFAULT)) < 0)
        return FAIL;

    /* get space */
    if((sid = H5Aget_space(aid)) < 0)
        goto out;

    /* get type */
    if((tid = H5Aget_type(aid)) < 0)
        goto out;

    /* get the size */
    if((nbytes = H5Tget_size(tid)) == 0)
        goto out;

    /* allocate a temporary buffer */
    buf = (char*)HDmalloc(nbytes * sizeof(char));
    if (buf == NULL)
        goto out;

    /* read */
    if (H5Aread(aid,tid,buf) < 0)
        goto out;

    /* compute the string length which will fit into the user's buffer */
    copy_len = MIN(size-1, nbytes);

    /* copy all/some of the name */
    if (name) {
        HDmemcpy(name, buf, copy_len);

        /* terminate the string */
        name[copy_len]='\0';
    }

    /* close */
    if (H5Tclose(tid) < 0)
        goto out;
    if (H5Aclose(aid) < 0)
        goto out;
    if (H5Sclose(sid) < 0)
        goto out;
    if (buf)
        HDfree(buf);

    return (ssize_t)(nbytes - 1);

    /* error zone */
out:
    H5E_BEGIN_TRY {
        H5Aclose(aid);
        H5Tclose(tid);
        H5Sclose(sid);
    } H5E_END_TRY;
    if (buf)
        HDfree(buf);
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DSis_scale
*
* Purpose: check if the dataset DID is a dimension scale
*
* Return: 1, is, 0, not, FAIL, error
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 04, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

htri_t H5DSis_scale(hid_t did)
{
    hid_t      tid = -1;   /* attribute type ID */
    hid_t      aid = -1;   /* attribute ID */
    herr_t     has_class;  /* has the "CLASS" attribute */
    htri_t     is_ds;      /* boolean return value */
    H5I_type_t it;           /* ID type */
    char       *buf;         /* Name of attribute */
    hsize_t    storage_size; /* Size of storage for attribute */

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if ((it = H5Iget_type(did)) < 0)
        return FAIL;

    if(H5I_DATASET != it)
        return FAIL;

    /* try to find the attribute "CLASS" on the dataset */
    if((has_class = H5LT_find_attribute(did, "CLASS")) < 0)
        return FAIL;

    if(has_class == 0)
        is_ds = 0;

    else
    {
        if((aid = H5Aopen(did, "CLASS", H5P_DEFAULT)) < 0)
            goto out;

        if((tid = H5Aget_type(aid)) < 0)
            goto out;

        /* check to make sure attribute is a string */
        if(H5T_STRING != H5Tget_class(tid))
            goto out;

        /* check to make sure string is null-terminated */
        if(H5T_STR_NULLTERM != H5Tget_strpad(tid))
            goto out;

        /* allocate buffer large enough to hold string */
        if((storage_size = H5Aget_storage_size(aid)) == 0)
            goto out;

        buf = (char*)HDmalloc( (size_t)storage_size * sizeof(char) + 1);
        if(buf == NULL)
            goto out;

        /* Read the attribute */
        if(H5Aread(aid, tid, buf) < 0)
            goto out;

        /* compare strings */
        if(HDstrncmp(buf, DIMENSION_SCALE_CLASS, MIN(HDstrlen(DIMENSION_SCALE_CLASS),HDstrlen(buf)))==0)
            is_ds = 1;
        else
            is_ds = 0;

        HDfree(buf);

        if(H5Tclose(tid) < 0)
            goto out;

        if (H5Aclose(aid) < 0)
            goto out;


    }

    return is_ds;

    /* error zone */
out:
    H5E_BEGIN_TRY {
        H5Aclose(aid);
        H5Tclose(tid);
    } H5E_END_TRY;
    return FAIL;

}

/*-------------------------------------------------------------------------
* Function: H5DSget_num_scales
*
* Purpose: get the number of scales linked to the IDX dimension of dataset DID
*
* Return:
*   Success: number of scales
*   Failure: FAIL
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: January 13, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

int H5DSget_num_scales(hid_t did,
                       unsigned int idx)
{
    int        has_dimlist;
    hid_t      sid;          /* space ID */
    hid_t      tid = -1;     /* attribute type ID */
    hid_t      aid = -1;     /* attribute ID */
    int        rank;         /* rank of dataset */
    hvl_t      *buf = NULL;  /* VL buffer to store in the attribute */
    H5I_type_t it;           /* ID type */
    int        nscales;

    /*-------------------------------------------------------------------------
    * parameter checking
    *-------------------------------------------------------------------------
    */
    /* get ID type */
    if((it = H5Iget_type(did)) < 0)
        return FAIL;

    if(H5I_DATASET != it)
        return FAIL;

    /*-------------------------------------------------------------------------
    * the attribute "DIMENSION_LIST" on the >>data<< dataset must exist
    *-------------------------------------------------------------------------
    */
    /* get dataset space */
    if((sid = H5Dget_space(did)) < 0)
        return FAIL;

    /* get rank */
    if((rank = H5Sget_simple_extent_ndims(sid)) < 0)
        goto out;

    /* close dataset space */
    if(H5Sclose(sid) < 0)
        goto out;

    /* dimemsion index IDX range checking */
    if(idx >= (unsigned int )rank)
        return FAIL;

    /* try to find the attribute "DIMENSION_LIST" on the >>data<< dataset */
    if((has_dimlist = H5LT_find_attribute(did, DIMENSION_LIST)) < 0)
        return FAIL;

    /* it does not exist */
    if(has_dimlist == 0)
        return 0;

    /*-------------------------------------------------------------------------
    * the attribute exists, open it
    *-------------------------------------------------------------------------
    */
    else {
        if((aid = H5Aopen(did, DIMENSION_LIST, H5P_DEFAULT)) < 0)
            goto out;
        if((tid = H5Aget_type(aid)) < 0)
            goto out;
        if((sid = H5Aget_space(aid)) < 0)
            goto out;

        /* allocate and initialize the VL */
        buf = (hvl_t *)HDmalloc((size_t)rank * sizeof(hvl_t));
        if(buf == NULL)
            goto out;

        /* read */
        if(H5Aread(aid, tid, buf) < 0)
            goto out;

        nscales = (int)buf[idx].len;

        /* close */
        if(H5Treclaim(tid, sid, H5P_DEFAULT, buf) < 0)
            goto out;
        if(H5Sclose(sid) < 0)
            goto out;
        if(H5Tclose(tid) < 0)
            goto out;
        if(H5Aclose(aid) < 0)
            goto out;
        HDfree(buf);
        buf = NULL;
    } /* has_dimlist */

    return nscales;

    /* error zone */
out:
    H5E_BEGIN_TRY {
        H5Sclose(sid);
        H5Aclose(aid);
        H5Tclose(tid);
    } H5E_END_TRY;

    if(buf)
        HDfree(buf);

    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DS_is_reserved
*
* Purpose: Verify that a dataset's CLASS is either an image, palette or table
*
* Return: true, false, fail
*
* Programmer: pvn@ncsa.uiuc.edu
*
* Date: March 19, 2005
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

static
herr_t H5DS_is_reserved(hid_t did)
{
    int    has_class;
    hid_t  tid = -1;
    hid_t  aid = -1;
    char *buf;            /* Name of attribute */
    hsize_t storage_size; /* Size of storage for attribute */
    herr_t ret;

    /* try to find the attribute "CLASS" on the dataset */
    if((has_class = H5LT_find_attribute(did, "CLASS")) < 0)
        return -1;

    if(has_class ==  0)
        return 0;

    assert(has_class ==  1);
    if((aid = H5Aopen(did, "CLASS", H5P_DEFAULT)) < 0)
        goto out;

    if((tid = H5Aget_type(aid)) < 0)
        goto out;

    /* check to make sure attribute is a string */
    if(H5T_STRING != H5Tget_class(tid))
      goto out;

    /* check to make sure string is null-terminated */
    if(H5T_STR_NULLTERM != H5Tget_strpad(tid))
      goto out;

    /* allocate buffer large enough to hold string */
    if((storage_size = H5Aget_storage_size(aid)) == 0)
      goto out;

    buf = (char*)HDmalloc( (size_t)storage_size * sizeof(char) + 1);
    if(buf == NULL)
      goto out;

    /* Read the attribute */
    if(H5Aread(aid, tid, buf) < 0)
      goto out;


    if(HDstrncmp(buf, IMAGE_CLASS, MIN(HDstrlen(IMAGE_CLASS),HDstrlen(buf))) == 0 ||
       HDstrncmp(buf, PALETTE_CLASS, MIN(HDstrlen(PALETTE_CLASS),HDstrlen(buf))) == 0 ||
       HDstrncmp(buf, TABLE_CLASS, MIN(HDstrlen(TABLE_CLASS),HDstrlen(buf))) == 0 )
        ret = 1;
    else
        ret = 0;

    HDfree(buf);

    if (H5Tclose(tid) < 0)
        goto out;

    if (H5Aclose(aid) < 0)
        goto out;


    return ret;

    /* error zone */
out:
    H5E_BEGIN_TRY
    {
        H5Tclose(tid);
        H5Aclose(aid);
    } H5E_END_TRY;
    return FAIL;
}

/*-------------------------------------------------------------------------
* Function: H5DS_get_REFLIST_type
*
* Purpose: This is a helper function to return a native type for
*          the REFERENCE_LIST attribute.
*
* Return: Type identifier on success and negative on failure
*
* Programmer: epourmal@hdfgroup.org
*
* Date: May 22, 2010
*
* Comments:
*
* Modifications:
*
*-------------------------------------------------------------------------
*/

static
hid_t H5DS_get_REFLIST_type(void)
{
    hid_t ntid_t = -1;

    /* Build native type that corresponds to compound datatype
       used to store ds_list_t structure in the REFERENCE_LIST
       attribute */

    if((ntid_t = H5Tcreate(H5T_COMPOUND, sizeof(ds_list_t))) < 0)
        goto out;

    if(H5Tinsert(ntid_t, "dataset", HOFFSET(ds_list_t,ref), H5T_STD_REF_OBJ) < 0)
        goto out;

    if(H5Tinsert(ntid_t, "dimension", HOFFSET(ds_list_t, dim_idx), H5T_NATIVE_INT) < 0)
        goto out;

    return ntid_t;
out:
    H5E_BEGIN_TRY {
        H5Tclose(ntid_t);
    } H5E_END_TRY;
    return FAIL;
}