path: root/src/H5Dcontig.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.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Programmer: 	Quincey Koziol <koziol@ncsa.uiuc.edu>
 *	       	Thursday, September 28, 2000
 *
 * Purpose:
 *      Contiguous dataset I/O functions. These routines are similar to
 *      the H5D_chunk_* routines and really only an abstract way of dealing
 *      with the data sieve buffer from H5F_seq_read/write.
 */

/****************/
/* Module Setup */
/****************/

#include "H5Dmodule.h"          /* This source code file is part of the H5D module */


/***********/
/* Headers */
/***********/
#include "H5private.h"      /* Generic Functions            */
#include "H5Dpkg.h"         /* Dataset functions            */
#include "H5Eprivate.h"     /* Error handling               */
#include "H5Fprivate.h"     /* Files                        */
#include "H5FDprivate.h"    /* File drivers                 */
#include "H5FLprivate.h"    /* Free Lists                   */
#include "H5Iprivate.h"     /* IDs                          */
#include "H5MFprivate.h"    /* File memory management       */
#include "H5FOprivate.h"    /* File objects                 */
#include "H5Oprivate.h"     /* Object headers               */
#include "H5Pprivate.h"     /* Property lists               */
#include "H5VMprivate.h"    /* Vector and array functions   */


/****************/
/* Local Macros */
/****************/


/******************/
/* Local Typedefs */
/******************/

/* Callback info for sieve buffer readvv operation */
typedef struct H5D_contig_readvv_sieve_ud_t {
    H5F_t *file;                /* File for dataset */
    H5D_rdcdc_t *dset_contig;   /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig;    /* Contiguous storage info for this I/O operation */
    unsigned char *rbuf;        /* Pointer to buffer to fill */
    hid_t dxpl_id;              /* DXPL for operation */
} H5D_contig_readvv_sieve_ud_t;

/* Callback info for [plain] readvv operation */
typedef struct H5D_contig_readvv_ud_t {
    H5F_t *file;                /* File for dataset */
    haddr_t dset_addr;          /* Address of dataset */
    unsigned char *rbuf;        /* Pointer to buffer to fill */
    hid_t dxpl_id;              /* DXPL for operation */
} H5D_contig_readvv_ud_t;

/* Callback info for sieve buffer writevv operation */
typedef struct H5D_contig_writevv_sieve_ud_t {
    H5F_t *file;                /* File for dataset */
    H5D_rdcdc_t *dset_contig;   /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig;    /* Contiguous storage info for this I/O operation */
    const unsigned char *wbuf;  /* Pointer to buffer to write */
    hid_t dxpl_id;              /* DXPL for operation */
} H5D_contig_writevv_sieve_ud_t;

/* Callback info for [plain] writevv operation */
typedef struct H5D_contig_writevv_ud_t {
    H5F_t *file;                /* File for dataset */
    haddr_t dset_addr;          /* Address of dataset */
    const unsigned char *wbuf;  /* Pointer to buffer to write */
    hid_t dxpl_id;              /* DXPL for operation */
} H5D_contig_writevv_ud_t;


/********************/
/* Local Prototypes */
/********************/

/* Layout operation callbacks */
static herr_t H5D__contig_construct(H5F_t *f, H5D_t *dset);
static herr_t H5D__contig_init(H5F_t *f, hid_t dxpl_id, const H5D_t *dset,
    hid_t dapl_id);
static herr_t H5D__contig_io_init(H5D_io_info_t *io_info, const H5D_type_info_t *type_info, 
    hsize_t nelmts, const H5S_t *file_space, const H5S_t *mem_space, H5D_dset_info_t *dinfo);
static ssize_t H5D__contig_readvv(const H5D_io_info_t *io_info,
    size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_offset_arr[],
    size_t mem_max_nseq, size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_offset_arr[]);
static ssize_t H5D__contig_writevv(const H5D_io_info_t *io_info,
    size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_offset_arr[],
    size_t mem_max_nseq, size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_offset_arr[]);
static herr_t H5D__contig_flush(H5D_t *dset, hid_t dxpl_id);

/* Helper routines */
static herr_t H5D__contig_write_one(H5D_io_info_t *io_info, hsize_t offset,
    size_t size);


/*********************/
/* Package Variables */
/*********************/

/* Contiguous storage layout I/O ops */
const H5D_layout_ops_t H5D_LOPS_CONTIG[1] = {{
    H5D__contig_construct,
    H5D__contig_init,
    H5D__contig_is_space_alloc,
    H5D__contig_io_init,
    H5D__contig_read,
    H5D__contig_write,
#ifdef H5_HAVE_PARALLEL
    H5D__collective_read,
    H5D__collective_write,
#endif /* H5_HAVE_PARALLEL */
    H5D__contig_readvv,
    H5D__contig_writevv,
    H5D__contig_flush,
    H5D__piece_io_term,
    NULL
}};


/*******************/
/* Local Variables */
/*******************/

/* Declare a PQ free list to manage the sieve buffer information */
H5FL_BLK_DEFINE(sieve_buf);

/* Declare extern the free list to manage blocks of type conversion data */
H5FL_BLK_EXTERN(type_conv);

/* Declare extern the free list to manage the H5D_chunk_info_t struct */
H5FL_EXTERN(H5D_chunk_info_t);


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_alloc
 *
 * Purpose:	Allocate file space for a contiguously stored dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		April 19, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_alloc(H5F_t *f, hid_t dxpl_id, H5O_storage_contig_t *storage /*out */ )
{
    herr_t ret_value = SUCCEED;   /* Return value */

    FUNC_ENTER_PACKAGE

    /* check args */
    HDassert(f);
    HDassert(storage);

    /* Allocate space for the contiguous data */
    if(HADDR_UNDEF == (storage->addr = H5MF_alloc(f, H5FD_MEM_DRAW, dxpl_id, storage->size)))
        HGOTO_ERROR(H5E_IO, H5E_NOSPACE, FAIL, "unable to reserve file space")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_alloc */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_fill
 *
 * Purpose:	Write fill values to a contiguously stored dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		August 22, 2002
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_fill(const H5D_io_info_t *io_info)
{
    const H5D_t *dset = io_info->dset;   /* the dataset pointer */
    H5D_io_info_t ioinfo;       /* Dataset I/O info */
    H5D_dset_info_t dset_info;  /* Dset info */
    H5D_storage_t store;        /* Union of storage info for dataset */
    H5D_dxpl_cache_t _dxpl_cache;       /* Data transfer property cache buffer */
    H5D_dxpl_cache_t *dxpl_cache = &_dxpl_cache;   /* Data transfer property cache */
    hssize_t    snpoints;       /* Number of points in space (for error checking) */
    size_t      npoints;        /* Number of points in space */
    hsize_t	offset;         /* Offset of dataset */
#ifdef H5_HAVE_PARALLEL
    MPI_Comm	mpi_comm = MPI_COMM_NULL;	/* MPI communicator for file */
    int         mpi_rank = (-1);  /* This process's rank  */
    int         mpi_code;       /* MPI return code */
    hbool_t     blocks_written = FALSE; /* Flag to indicate that chunk was actually written */
    hbool_t     using_mpi = FALSE;      /* Flag to indicate that the file is being accessed with an MPI-capable file driver */
#endif /* H5_HAVE_PARALLEL */
    hid_t       md_dxpl_id = io_info->md_dxpl_id;
    hid_t       raw_dxpl_id = io_info->raw_dxpl_id;
    H5D_fill_buf_info_t fb_info;        /* Dataset's fill buffer info */
    hbool_t     fb_info_init = FALSE;   /* Whether the fill value buffer has been initialized */
    herr_t	ret_value = SUCCEED;	/* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(TRUE == H5P_isa_class(md_dxpl_id, H5P_DATASET_XFER));
    HDassert(TRUE == H5P_isa_class(raw_dxpl_id, H5P_DATASET_XFER));
    HDassert(dset && H5D_CONTIGUOUS == dset->shared->layout.type);
    HDassert(H5F_addr_defined(dset->shared->layout.storage.u.contig.addr));
    HDassert(dset->shared->layout.storage.u.contig.size > 0);
    HDassert(dset->shared->space);
    HDassert(dset->shared->type);

#ifdef H5_HAVE_PARALLEL
    /* Retrieve MPI parameters */
    if(H5F_HAS_FEATURE(dset->oloc.file, H5FD_FEAT_HAS_MPI)) {
        /* Get the MPI communicator */
        if(MPI_COMM_NULL == (mpi_comm = H5F_mpi_get_comm(dset->oloc.file)))
            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI communicator")

        /* Get the MPI rank */
        if((mpi_rank = H5F_mpi_get_rank(dset->oloc.file)) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank")

        /* Set the MPI-capable file driver flag */
        using_mpi = TRUE;
    } /* end if */
#endif  /* H5_HAVE_PARALLEL */

    /* Fill the DXPL cache values for later use */
    if(H5D__get_dxpl_cache(raw_dxpl_id, &dxpl_cache) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't fill dxpl cache")

    /* Initialize storage info for this dataset */
    store.contig.dset_addr = dset->shared->layout.storage.u.contig.addr;
    store.contig.dset_size = dset->shared->layout.storage.u.contig.size;

    /* Get the number of elements in the dataset's dataspace */
    if((snpoints = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "dataset has negative number of elements")
    H5_CHECKED_ASSIGN(npoints, size_t, snpoints, hssize_t);

    /* Initialize the fill value buffer */
    if(H5D__fill_init(&fb_info, NULL, NULL, NULL, NULL, NULL,
            &dset->shared->dcpl_cache.fill,
            dset->shared->type, dset->shared->type_id, npoints,
            dxpl_cache->max_temp_buf, md_dxpl_id) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't initialize fill buffer info")
    fb_info_init = TRUE;

    /* Start at the beginning of the dataset */
    offset = 0;

    /* Simple setup for dataset I/O info struct */
    ioinfo.dxpl_cache = dxpl_cache;
    ioinfo.op_type = H5D_IO_OP_WRITE;
    ioinfo.md_dxpl_id = H5AC_ind_read_dxpl_id;
    ioinfo.raw_dxpl_id = raw_dxpl_id;

    dset_info.dset = (H5D_t *)dset;
    dset_info.store = &store;
    dset_info.u.wbuf = fb_info.fill_buf;
    ioinfo.dsets_info = &dset_info;

    /*
     * Fill the entire current extent with the fill value.  We can do
     * this quite efficiently by making sure we copy the fill value
     * in relatively large pieces.
     */

    /* Loop through writing the fill value to the dataset */
    while(npoints > 0) {
        size_t curr_points;     /* Number of elements to write on this iteration of the loop */
        size_t size;            /* Size of buffer to write */

        /* Compute # of elements and buffer size to write for this iteration */
        curr_points = MIN(fb_info.elmts_per_buf, npoints);
        size = curr_points * fb_info.file_elmt_size;

        /* Check for VL datatype & non-default fill value */
        if(fb_info.has_vlen_fill_type)
            /* Re-fill the buffer to use for this I/O operation */
            if(H5D__fill_refill_vl(&fb_info, curr_points, md_dxpl_id) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTCONVERT, FAIL, "can't refill fill value buffer")

#ifdef H5_HAVE_PARALLEL
            /* Check if this file is accessed with an MPI-capable file driver */
            if(using_mpi) {
                /* Write the chunks out from only one process */
                /* !! Use the internal "independent" DXPL!! -QAK */
                if(H5_PAR_META_WRITE == mpi_rank)
                    if(H5D__contig_write_one(&ioinfo, offset, size) < 0)
                        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset")

                /* Indicate that blocks are being written */
                blocks_written = TRUE;
            } /* end if */
            else {
#endif /* H5_HAVE_PARALLEL */
                H5_CHECK_OVERFLOW(size, size_t, hsize_t);
                if(H5D__contig_write_one(&ioinfo, offset, size) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset")
#ifdef H5_HAVE_PARALLEL
            } /* end else */
#endif /* H5_HAVE_PARALLEL */

          npoints -= curr_points;
          offset += size;
      } /* end while */

#ifdef H5_HAVE_PARALLEL
    /* Only need to block at the barrier if we actually wrote fill values */
    /* And if we are using an MPI-capable file driver */
    if(using_mpi && blocks_written) {
        /* Wait at barrier to avoid race conditions where some processes are
         * still writing out fill values and other processes race ahead to data
         * in, getting bogus data.
         */
        if(MPI_SUCCESS != (mpi_code = MPI_Barrier(mpi_comm)))
            HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)
    } /* end if */
#endif /* H5_HAVE_PARALLEL */

done:
    /* Release the fill buffer info, if it's been initialized */
    if(fb_info_init && H5D__fill_term(&fb_info) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release fill buffer info")

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_fill() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_delete
 *
 * Purpose:	Delete the file space for a contiguously stored dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		March 20, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_delete(H5F_t *f, hid_t dxpl_id, const H5O_storage_t *storage)
{
    herr_t ret_value = SUCCEED;   /* Return value */

    FUNC_ENTER_PACKAGE

    /* check args */
    HDassert(f);
    HDassert(storage);

    /* Free the file space for the chunk */
    if(H5MF_xfree(f, H5FD_MEM_DRAW, dxpl_id, storage->u.contig.addr, storage->u.contig.size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "unable to free contiguous storage space")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_delete */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_construct
 *
 * Purpose:	Constructs new contiguous layout information for dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, May 22, 2008
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_construct(H5F_t *f, H5D_t *dset)
{
    hssize_t snelmts;                   /* Temporary holder for number of elements in dataspace */
    hsize_t nelmts;                     /* Number of elements in dataspace */
    size_t dt_size;                     /* Size of datatype */
    hsize_t tmp_size;                   /* Temporary holder for raw data size */
    size_t tmp_sieve_buf_size;          /* Temporary holder for sieve buffer size */
    unsigned u;                         /* Local index variable */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_STATIC

    /* Sanity checks */
    HDassert(f);
    HDassert(dset);

    /*
     * The maximum size of the dataset cannot exceed the storage size.
     * Also, only the slowest varying dimension of a simple dataspace
     * can be extendible (currently only for external data storage).
     */

    /* Check for invalid dataset dimensions */
    for(u = 0; u < dset->shared->ndims; u++)
        if(dset->shared->max_dims[u] > dset->shared->curr_dims[u])
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "extendible contiguous non-external dataset not allowed")

    /* Retrieve the number of elements in the dataspace */
    if((snelmts = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve number of elements in dataspace")
    nelmts = (hsize_t)snelmts;

    /* Get the datatype's size */
    if(0 == (dt_size = H5T_GET_SIZE(dset->shared->type)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve size of datatype")

    /* Compute the size of the dataset's contiguous storage */
    tmp_size = nelmts * dt_size;

    /* Check for overflow during multiplication */
    if(nelmts != (tmp_size / dt_size))
        HGOTO_ERROR(H5E_DATASET, H5E_OVERFLOW, FAIL, "size of dataset's storage overflowed")

    /* Assign the dataset's contiguous storage size */
    dset->shared->layout.storage.u.contig.size = tmp_size;

    /* Get the sieve buffer size for the file */
    tmp_sieve_buf_size = H5F_SIEVE_BUF_SIZE(f);

    /* Adjust the sieve buffer size to the smaller one between the dataset size and the buffer size
     * from the file access property. (SLU - 2012/3/30) */
    if(tmp_size < tmp_sieve_buf_size)
        dset->shared->cache.contig.sieve_buf_size = tmp_size;
    else
        dset->shared->cache.contig.sieve_buf_size = tmp_sieve_buf_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_construct() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_init
 *
 * Purpose:	Initialize the contiguous info for a dataset.  This is
 *		called when the dataset is initialized.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Friday, August 28, 2015
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_init(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id,
    const H5D_t *dset, hid_t H5_ATTR_UNUSED dapl_id)
{
    hsize_t tmp_size;                   /* Temporary holder for raw data size */
    size_t tmp_sieve_buf_size;          /* Temporary holder for sieve buffer size */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_STATIC

    /* Sanity check */
    HDassert(f);
    HDassert(dset);

    /* Compute the size of the contiguous storage for versions of the
     * layout message less than version 3 because versions 1 & 2 would
     * truncate the dimension sizes to 32-bits of information. - QAK 5/26/04
     */
    if(dset->shared->layout.version < 3) {
        hssize_t snelmts;                   /* Temporary holder for number of elements in dataspace */
        hsize_t nelmts;                     /* Number of elements in dataspace */
        size_t dt_size;                     /* Size of datatype */

        /* Retrieve the number of elements in the dataspace */
        if((snelmts = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve number of elements in dataspace")
        nelmts = (hsize_t)snelmts;

        /* Get the datatype's size */
        if(0 == (dt_size = H5T_GET_SIZE(dset->shared->type)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve size of datatype")

        /* Compute the size of the dataset's contiguous storage */
        tmp_size = nelmts * dt_size;

        /* Check for overflow during multiplication */
        if(nelmts != (tmp_size / dt_size))
            HGOTO_ERROR(H5E_DATASET, H5E_OVERFLOW, FAIL, "size of dataset's storage overflowed")

        /* Assign the dataset's contiguous storage size */
        dset->shared->layout.storage.u.contig.size = tmp_size;
    } /* end if */
    else
        tmp_size = dset->shared->layout.storage.u.contig.size;

    /* Get the sieve buffer size for the file */
    tmp_sieve_buf_size = H5F_SIEVE_BUF_SIZE(dset->oloc.file);

    /* Adjust the sieve buffer size to the smaller one between the dataset size and the buffer size
     * from the file access property.  (SLU - 2012/3/30) */
    if(tmp_size < tmp_sieve_buf_size)
        dset->shared->cache.contig.sieve_buf_size = tmp_size;
    else
        dset->shared->cache.contig.sieve_buf_size = tmp_sieve_buf_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_init() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_is_space_alloc
 *
 * Purpose:	Query if space is allocated for layout
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, January 15, 2009
 *
 *-------------------------------------------------------------------------
 */
hbool_t
H5D__contig_is_space_alloc(const H5O_storage_t *storage)
{
    hbool_t ret_value = FALSE;          /* Return value */

    FUNC_ENTER_PACKAGE_NOERR

    /* Sanity checks */
    HDassert(storage);

    /* Set return value */
    ret_value = (hbool_t)H5F_addr_defined(storage->u.contig.addr);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_is_space_alloc() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_io_init
 *
 * Purpose:	Performs initialization before any sort of I/O on the raw data
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Jonathan Kim
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_io_init(H5D_io_info_t *io_info,
    const H5D_type_info_t H5_ATTR_UNUSED *type_info, hsize_t nelmts,
    const H5S_t *file_space, const H5S_t *mem_space, H5D_dset_info_t *dinfo)
{
    H5D_t *dataset = dinfo->dset;     /* Local pointer to dataset info */

    hssize_t old_offset[H5O_LAYOUT_NDIMS];  /* Old selection offset */
    htri_t file_space_normalized = FALSE;   /* File dataspace was normalized */

    int sm_ndims;               /* The number of dimensions of the memory buffer's dataspace (signed) */
    int sf_ndims;               /* The number of dimensions of the file dataspace (signed) */
    H5S_class_t fsclass_type;   /* file space class type */
    H5S_sel_type fsel_type;     /* file space selection type */
    hbool_t sel_hyper_flag;

    herr_t ret_value = SUCCEED;	/* Return value		*/

    FUNC_ENTER_STATIC

    dinfo->store->contig.dset_addr = dataset->shared->layout.storage.u.contig.addr;
    dinfo->store->contig.dset_size = dataset->shared->layout.storage.u.contig.size;

    /* Get layout for dataset */
    dinfo->layout = &(dataset->shared->layout);
    /* num of element selected */
    dinfo->nelmts = nelmts;

    /* Check if the memory space is scalar & make equivalent memory space */
    if((sm_ndims = H5S_GET_EXTENT_NDIMS(mem_space)) < 0)
        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "unable to get dimension number")
    /* Set the number of dimensions for the memory dataspace */
    H5_CHECKED_ASSIGN(dinfo->m_ndims, unsigned, sm_ndims, int);

    /* Get dim number and dimensionality for each dataspace */
    if((sf_ndims = H5S_GET_EXTENT_NDIMS(file_space)) < 0)
        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "unable to get dimension number")
    /* Set the number of dimensions for the file dataspace */
    H5_CHECKED_ASSIGN(dinfo->f_ndims, unsigned, sf_ndims, int);

    if(H5S_get_simple_extent_dims(file_space, dinfo->f_dims, NULL) < 0)
        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "unable to get dimensionality")

    /* Normalize hyperslab selections by adjusting them by the offset */
    /* (It might be worthwhile to normalize both the file and memory dataspaces
     * before any (contiguous, chunked, etc) file I/O operation, in order to
     * speed up hyperslab calculations by removing the extra checks and/or
     * additions involving the offset and the hyperslab selection -QAK)
     */
    if((file_space_normalized = H5S_hyper_normalize_offset((H5S_t *)file_space, old_offset)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to normalize dataspace by offset")

    /* Initialize "last chunk" information */
    dinfo->last_index = (hsize_t)-1;
    dinfo->last_piece_info = NULL;

    /* Point at the dataspaces */
    dinfo->file_space = file_space;
    dinfo->mem_space = mem_space;

    /* Only need single skip list point over multiple read/write IO 
     * and multiple dsets until H5D_close. Thus check both 
     * since io_info->sel_pieces only lives single write/read IO, 
     * even cache.sel_pieces lives until Dclose */
    if(NULL == dataset->shared->cache.sel_pieces &&
       NULL == io_info->sel_pieces) {
        if(NULL == (dataset->shared->cache.sel_pieces = H5SL_create(H5SL_TYPE_HADDR, NULL)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTCREATE, FAIL, "can't create skip list for piece selections")

        /* keep the skip list in cache, so do not need to recreate until close */
        io_info->sel_pieces = dataset->shared->cache.sel_pieces;
    } /* end if */

    /* this is need when multiple write/read occurs on the same dsets,
     * just pass the previously created pointer */
    if (NULL == io_info->sel_pieces)
        io_info->sel_pieces = dataset->shared->cache.sel_pieces;

    HDassert(io_info->sel_pieces);

    /* We are not using single element mode */
    dinfo->use_single = FALSE;

    /* Get type of space class on disk */
    if((fsclass_type = H5S_GET_EXTENT_TYPE(file_space)) < H5S_SCALAR)
        HGOTO_ERROR(H5E_FSPACE, H5E_BADTYPE, FAIL, "unable to get fspace class type")

    /* Get type of selection on disk & in memory */
    if((fsel_type = H5S_GET_SELECT_TYPE(file_space)) < H5S_SEL_NONE)
        HGOTO_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to get type of selection")
    if((dinfo->msel_type = H5S_GET_SELECT_TYPE(mem_space)) < H5S_SEL_NONE)
        HGOTO_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to get type of selection")

    /* if class type is scalar or null for contiguous dset */
    if(fsclass_type == H5S_SCALAR || fsclass_type == H5S_NULL)
        sel_hyper_flag = FALSE;
    /* if class type is H5S_SIMPLE & if selection is NONE or POINTS */
    else if(fsel_type == H5S_SEL_POINTS || fsel_type == H5S_SEL_NONE)
        sel_hyper_flag = FALSE;
    else
        sel_hyper_flag = TRUE;

    /* if selected elements exist */
    if (dinfo->nelmts) {
        unsigned    u;
        H5D_chunk_info_t *new_piece_info;   /* piece information to insert into skip list */

        /* Get copy of dset file_space, so it can be changed temporarily 
         * purpose 
         * This tmp_fspace allows multiple write before close dset */
        H5S_t *tmp_fspace;                  /* Temporary file dataspace */
        /* Create "temporary" chunk for selection operations (copy file space) */
        if(NULL == (tmp_fspace = H5S_copy(dinfo->file_space, TRUE, FALSE)))
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space")

        /* Actions specific to hyperslab selections */
        if(sel_hyper_flag) {
            /* Sanity check */
            HDassert(dinfo->f_ndims > 0);

            /* Make certain selections are stored in span tree form (not "optimized hyperslab" or "all") */
            if(H5S_hyper_convert(tmp_fspace) < 0) {
                (void)H5S_close(tmp_fspace);
                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to convert selection to span trees")
            } /* end if */
        } /* end if */

        /* Add temporary chunk to the list of pieces */
        /* collect piece_info into Skip List */
        /* Allocate the file & memory chunk information */
        if (NULL==(new_piece_info = H5FL_MALLOC (H5D_chunk_info_t))) {
            (void)H5S_close(tmp_fspace);
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate chunk info")
        } /* end if */

        /* Set the piece index */
        new_piece_info->index = 0;

        /* Set the file chunk dataspace */
        new_piece_info->fspace = tmp_fspace;
        new_piece_info->fspace_shared = FALSE;

        /* Set the memory chunk dataspace */
        /* same as one chunk, just use dset mem space */
        new_piece_info->mspace = mem_space;

        /* set true for sharing mem space with dset, which means
         * fspace gets free by applicaton H5Sclose(), and
         * doesn't require providing layout_ops.io_term() for H5D_LOPS_CONTIG.
         */
        new_piece_info->mspace_shared = TRUE;

        /* Copy the piece's coordinates */
        for(u = 0; u < dinfo->f_ndims; u++)
            new_piece_info->scaled[u] = 0;
        new_piece_info->scaled[dinfo->f_ndims] = 0;

        /* make connection to related dset info from this piece_info */
        new_piece_info->dset_info = dinfo;

        /* get dset file address for piece */
        new_piece_info->faddr = dinfo->dset->shared->layout.storage.u.contig.addr;

        /* Save piece to last_piece_info so it is freed at the end of the
         * operation */
        dinfo->last_piece_info = new_piece_info;

        /* insert piece info */
        if(H5SL_insert(io_info->sel_pieces, new_piece_info, &new_piece_info->faddr) < 0) {
            /* mimic H5D__free_piece_info */
            H5S_select_all(new_piece_info->fspace, TRUE);
            H5FL_FREE(H5D_chunk_info_t, new_piece_info);
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert chunk into skip list")
        } /* end if */
        H5_CHECKED_ASSIGN(new_piece_info->piece_points, uint32_t, nelmts, hssize_t);
        
        /* only scratch for this dset */
        /* Clean hyperslab span's "scratch" information */
        if(sel_hyper_flag)
            if(H5S_hyper_reset_scratch(new_piece_info->fspace) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "unable to reset span scratch info")
    } /* end if */

done:
    if(ret_value < 0) {
        if(H5D__piece_io_term(io_info, dinfo) < 0)
            HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release chunk mapping")
    } /* end if */

    if(file_space_normalized) {
        /* (Casting away const OK -QAK) */
        if(H5S_hyper_denormalize_offset((H5S_t *)file_space, old_offset) < 0)
            HDONE_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to normalize dataspace by offset")
    } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_io_init() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_read
 *
 * Purpose:	Read from a contiguous dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Raymond Lu
 *		Thursday, April 10, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_read(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
    hsize_t nelmts, const H5S_t *file_space, const H5S_t *mem_space,
    H5D_dset_info_t *dinfo)
{
    herr_t	ret_value = SUCCEED;	/*return value		*/

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    HDassert(io_info);
    HDassert(dinfo->u.rbuf);
    HDassert(type_info);
    HDassert(mem_space);
    HDassert(file_space);

    io_info->dset = io_info->dsets_info[0].dset;

    /* Read data */
    if((io_info->io_ops.single_read)(io_info, type_info, nelmts, file_space, mem_space) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "contiguous read failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_read() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_write
 *
 * Purpose:	Write to a contiguous dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Raymond Lu
 *		Thursday, April 10, 2003
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_write(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
    hsize_t nelmts, const H5S_t *file_space, const H5S_t *mem_space,
    H5D_dset_info_t *dinfo)
{
    herr_t	ret_value = SUCCEED;	/*return value		*/

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    HDassert(io_info);
    HDassert(dinfo->u.wbuf);
    HDassert(type_info);
    HDassert(mem_space);
    HDassert(file_space);

    io_info->dset = io_info->dsets_info[0].dset;

    /* Write data */
    if((io_info->io_ops.single_write)(io_info, type_info, nelmts, file_space, mem_space) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "contiguous write failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_write() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_write_one
 *
 * Purpose:	Writes some data from a dataset into a buffer.
 *		The data is contiguous.	 The address is relative to the base
 *		address for the file.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, September 28, 2000
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_write_one(H5D_io_info_t *io_info, hsize_t offset, size_t size)
{
    hsize_t dset_off = offset;  /* Offset in dataset */
    size_t dset_len = size;     /* Length in dataset */
    size_t dset_curr_seq = 0;   /* "Current sequence" in dataset */
    hsize_t mem_off = 0;        /* Offset in memory */
    size_t mem_len = size;      /* Length in memory */
    size_t mem_curr_seq = 0;    /* "Current sequence" in memory */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    HDassert(io_info);

    if(H5D__contig_writevv(io_info, (size_t)1, &dset_curr_seq, &dset_len, &dset_off,
            (size_t)1, &mem_curr_seq, &mem_len, &mem_off) < 0)
        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "vector write failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_write_one() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv_sieve_cb
 *
 * Purpose:	Callback operator for H5D__contig_readvv() with sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, Sept 30, 2010
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_readvv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
    void *_udata)
{
    H5D_contig_readvv_sieve_ud_t *udata = (H5D_contig_readvv_sieve_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    H5F_t *file = udata->file;        /* File for dataset */
    H5D_rdcdc_t *dset_contig = udata->dset_contig; /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig = udata->store_contig;    /* Contiguous storage info for this I/O operation */
    unsigned char *buf;         /* Pointer to buffer to fill */
    haddr_t addr;               /* Actual address to read */
    haddr_t sieve_start = HADDR_UNDEF, sieve_end = HADDR_UNDEF;     /* Start & end locations of sieve buffer */
    haddr_t contig_end;         /* End locations of block to write */
    size_t sieve_size = (size_t)-1;   /* Size of sieve buffer */
    haddr_t rel_eoa;	        /* Relative end of file address	*/
    hsize_t max_data;           /* Actual maximum size of data to cache */
    hsize_t min;                /* temporary minimum value (avoids some ugly macro nesting) */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    /* Stash local copies of these value */
    if(dset_contig->sieve_buf != NULL) {
        sieve_start = dset_contig->sieve_loc;
        sieve_size = dset_contig->sieve_size;
        sieve_end = sieve_start + sieve_size;
    } /* end if */

    /* Compute offset on disk */
    addr = store_contig->dset_addr + dst_off;

    /* Compute offset in memory */
    buf = udata->rbuf + src_off;

    /* Check if the sieve buffer is allocated yet */
    if(NULL == dset_contig->sieve_buf) {
        /* Check if we can actually hold the I/O request in the sieve buffer */
        if(len > dset_contig->sieve_buf_size) {
            if(H5F_block_read(file, H5FD_MEM_DRAW, addr, len, udata->dxpl_id, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")
        } /* end if */
        else {
            /* Allocate room for the data sieve buffer */
            if(NULL == (dset_contig->sieve_buf = H5FL_BLK_CALLOC(sieve_buf, dset_contig->sieve_buf_size)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "memory allocation failed")

            /* Determine the new sieve buffer size & location */
            dset_contig->sieve_loc = addr;

            /* Make certain we don't read off the end of the file */
            if(HADDR_UNDEF == (rel_eoa = H5F_get_eoa(file, H5FD_MEM_DRAW)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size")

            /* Set up the buffer parameters */
            max_data = store_contig->dset_size - dst_off;

            /* Compute the size of the sieve buffer */
            min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size);
            H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

            /* Read the new sieve buffer */
            if(H5F_block_read(file, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")

            /* Grab the data out of the buffer (must be first piece of data in buffer ) */
            HDmemcpy(buf, dset_contig->sieve_buf, len);

            /* Reset sieve buffer dirty flag */
            dset_contig->sieve_dirty = FALSE;

            /* Stash local copies of these value */
            sieve_start = dset_contig->sieve_loc;
            sieve_size = dset_contig->sieve_size;
            sieve_end = sieve_start+sieve_size;
        } /* end else */
    } /* end if */
    else {
        /* Compute end of sequence to retrieve */
        contig_end = addr + len - 1;

        /* If entire read is within the sieve buffer, read it from the buffer */
        if(addr >= sieve_start && contig_end < sieve_end) {
            unsigned char *base_sieve_buf = dset_contig->sieve_buf + (addr - sieve_start);

            /* Grab the data out of the buffer */
            HDmemcpy(buf, base_sieve_buf, len);
        } /* end if */
        /* Entire request is not within this data sieve buffer */
        else {
            /* Check if we can actually hold the I/O request in the sieve buffer */
            if(len > dset_contig->sieve_buf_size) {
                /* Check for any overlap with the current sieve buffer */
                if((sieve_start >= addr && sieve_start < (contig_end + 1))
                        || ((sieve_end - 1) >= addr && (sieve_end - 1) < (contig_end + 1))) {
                    /* Flush the sieve buffer, if it's dirty */
                    if(dset_contig->sieve_dirty) {
                        /* Write to file */
                        if(H5F_block_write(file, H5FD_MEM_DRAW, sieve_start, sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = FALSE;
                    } /* end if */
                } /* end if */

                /* Read directly into the user's buffer */
                if(H5F_block_read(file, H5FD_MEM_DRAW, addr, len, udata->dxpl_id, buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")
            } /* end if */
            /* Element size fits within the buffer size */
            else {
                /* Flush the sieve buffer if it's dirty */
                if(dset_contig->sieve_dirty) {
                    /* Write to file */
                    if(H5F_block_write(file, H5FD_MEM_DRAW, sieve_start, sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

                    /* Reset sieve buffer dirty flag */
                    dset_contig->sieve_dirty = FALSE;
                } /* end if */

                /* Determine the new sieve buffer size & location */
                dset_contig->sieve_loc = addr;

                /* Make certain we don't read off the end of the file */
                if(HADDR_UNDEF == (rel_eoa = H5F_get_eoa(file, H5FD_MEM_DRAW)))
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size")

                /* Only need this when resizing sieve buffer */
                max_data = store_contig->dset_size - dst_off;

                /* Compute the size of the sieve buffer.
                 * Don't read off the end of the file, don't read past
                 * the end of the data element, and don't read more than
                 * the buffer size.
                 */
                min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size); 
                H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

                /* Update local copies of sieve information */
                sieve_start = dset_contig->sieve_loc;
                sieve_size = dset_contig->sieve_size;
                sieve_end = sieve_start + sieve_size;

                /* Read the new sieve buffer */
                if(H5F_block_read(file, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")

                /* Grab the data out of the buffer (must be first piece of data in buffer ) */
                HDmemcpy(buf, dset_contig->sieve_buf, len);

                /* Reset sieve buffer dirty flag */
                dset_contig->sieve_dirty = FALSE;
            } /* end else */
        } /* end else */
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_readvv_sieve_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv_cb
 *
 * Purpose:	Callback operator for H5D__contig_readvv() without sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, Sept 30, 2010
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_readvv_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_readvv_ud_t *udata = (H5D_contig_readvv_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_STATIC

    /* Write data */
    if(H5F_block_read(udata->file, H5FD_MEM_DRAW, (udata->dset_addr + dst_off),
            len, udata->dxpl_id, (udata->rbuf + src_off)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_readvv_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv
 *
 * Purpose:	Reads some data vectors from a dataset into a buffer.
 *		The data is contiguous.	 The address is the start of the dataset,
 *              relative to the base address for the file and the offsets and
 *              sequence lengths are in bytes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Friday, May 3, 2001
 *
 * Notes:
 *      Offsets in the sequences must be monotonically increasing
 *
 *-------------------------------------------------------------------------
 */
static ssize_t
H5D__contig_readvv(const H5D_io_info_t *io_info,
    size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_off_arr[],
    size_t mem_max_nseq, size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_off_arr[])
{
    H5D_dset_info_t dset_info;
    ssize_t ret_value = -1;     /* Return value */

    FUNC_ENTER_STATIC

    /* Check args */
    HDassert(io_info);
    HDassert(dset_curr_seq);
    HDassert(dset_len_arr);
    HDassert(dset_off_arr);
    HDassert(mem_curr_seq);
    HDassert(mem_len_arr);
    HDassert(mem_off_arr);

    dset_info = io_info->dsets_info[0];

    /* Check if data sieving is enabled */
    if(H5F_HAS_FEATURE(dset_info.dset->oloc.file, H5FD_FEAT_DATA_SIEVE)) {
        H5D_contig_readvv_sieve_ud_t udata;     /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.file = dset_info.dset->oloc.file;
        udata.dset_contig = &(dset_info.dset->shared->cache.contig);
        udata.store_contig = &(dset_info.store->contig);
        udata.rbuf = (unsigned char *)dset_info.u.rbuf;
        udata.dxpl_id = io_info->raw_dxpl_id;

        /* Call generic sequence operation routine */
        if((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr,
                mem_max_nseq, mem_curr_seq, mem_len_arr, mem_off_arr,
                H5D__contig_readvv_sieve_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized sieve buffer read")
    } /* end if */
    else {
        H5D_contig_readvv_ud_t udata;     /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.file = dset_info.dset->oloc.file;
        udata.dset_addr = dset_info.store->contig.dset_addr;
        udata.rbuf = (unsigned char *)dset_info.u.rbuf;
        udata.dxpl_id = io_info->raw_dxpl_id;

        /* Call generic sequence operation routine */
        if((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr,
                mem_max_nseq, mem_curr_seq, mem_len_arr, mem_off_arr,
                H5D__contig_readvv_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized read")
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_readvv() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv_sieve_cb
 *
 * Purpose:	Callback operator for H5D__contig_writevv() with sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, Sept 30, 2010
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_writevv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len,
    void *_udata)
{
    H5D_contig_writevv_sieve_ud_t *udata = (H5D_contig_writevv_sieve_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    H5F_t *file = udata->file;        /* File for dataset */
    H5D_rdcdc_t *dset_contig = udata->dset_contig; /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig = udata->store_contig;    /* Contiguous storage info for this I/O operation */
    const unsigned char *buf;   /* Pointer to buffer to fill */
    haddr_t addr;               /* Actual address to read */
    haddr_t sieve_start = HADDR_UNDEF, sieve_end = HADDR_UNDEF;     /* Start & end locations of sieve buffer */
    haddr_t contig_end;         /* End locations of block to write */
    size_t sieve_size = (size_t)-1; /* size of sieve buffer */
    haddr_t rel_eoa;	        /* Relative end of file address	*/
    hsize_t max_data;           /* Actual maximum size of data to cache */
    hsize_t min;                /* temporary minimum value (avoids some ugly macro nesting) */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    /* Stash local copies of these values */
    if(dset_contig->sieve_buf != NULL) {
        sieve_start = dset_contig->sieve_loc;
        sieve_size = dset_contig->sieve_size;
        sieve_end = sieve_start + sieve_size;
    } /* end if */

    /* Compute offset on disk */
    addr = store_contig->dset_addr + dst_off;

    /* Compute offset in memory */
    buf = udata->wbuf + src_off;

    /* No data sieve buffer yet, go allocate one */
    if(NULL == dset_contig->sieve_buf) {
        /* Check if we can actually hold the I/O request in the sieve buffer */
        if(len > dset_contig->sieve_buf_size) {
            if(H5F_block_write(file, H5FD_MEM_DRAW, addr, len, udata->dxpl_id, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")
        } /* end if */
        else {
            /* Allocate room for the data sieve buffer */
            if(NULL == (dset_contig->sieve_buf = H5FL_BLK_CALLOC(sieve_buf, dset_contig->sieve_buf_size)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "memory allocation failed")

            /* Clear memory */
            if(dset_contig->sieve_size > len)
                HDmemset(dset_contig->sieve_buf + len, 0, (dset_contig->sieve_size - len));

            /* Determine the new sieve buffer size & location */
            dset_contig->sieve_loc = addr;

            /* Make certain we don't read off the end of the file */
            if(HADDR_UNDEF == (rel_eoa = H5F_get_eoa(file, H5FD_MEM_DRAW)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size")

            /* Set up the buffer parameters */
            max_data = store_contig->dset_size - dst_off;

            /* Compute the size of the sieve buffer */
            min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size); 
            H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

            /* Check if there is any point in reading the data from the file */
            if(dset_contig->sieve_size > len) {
                /* Read the new sieve buffer */
                if(H5F_block_read(file, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")
            } /* end if */

            /* Grab the data out of the buffer (must be first piece of data in buffer ) */
            HDmemcpy(dset_contig->sieve_buf, buf, len);

            /* Set sieve buffer dirty flag */
            dset_contig->sieve_dirty = TRUE;

            /* Stash local copies of these values */
            sieve_start = dset_contig->sieve_loc;
            sieve_size = dset_contig->sieve_size;
            sieve_end = sieve_start + sieve_size;
        } /* end else */
    } /* end if */
    else {
        /* Compute end of sequence to retrieve */
        contig_end = addr + len - 1;

        /* If entire write is within the sieve buffer, write it to the buffer */
        if(addr >= sieve_start && contig_end < sieve_end) {
            unsigned char *base_sieve_buf = dset_contig->sieve_buf + (addr - sieve_start);

            /* Put the data into the sieve buffer */
            HDmemcpy(base_sieve_buf, buf, len);

            /* Set sieve buffer dirty flag */
            dset_contig->sieve_dirty = TRUE;
        } /* end if */
        /* Entire request is not within this data sieve buffer */
        else {
            /* Check if we can actually hold the I/O request in the sieve buffer */
            if(len > dset_contig->sieve_buf_size) {
                /* Check for any overlap with the current sieve buffer */
                if((sieve_start >= addr && sieve_start < (contig_end + 1))
                        || ((sieve_end - 1) >= addr && (sieve_end - 1) < (contig_end + 1))) {
                    /* Flush the sieve buffer, if it's dirty */
                    if(dset_contig->sieve_dirty) {
                        /* Write to file */
                        if(H5F_block_write(file, H5FD_MEM_DRAW, sieve_start, sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = FALSE;
                    } /* end if */

                    /* Force the sieve buffer to be re-read the next time */
                    dset_contig->sieve_loc = HADDR_UNDEF;
                    dset_contig->sieve_size = 0;
                } /* end if */

                /* Write directly from the user's buffer */
                if(H5F_block_write(file, H5FD_MEM_DRAW, addr, len, udata->dxpl_id, buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")
            } /* end if */
            /* Element size fits within the buffer size */
            else {
                /* Check if it is possible to (exactly) prepend or append to existing (dirty) sieve buffer */
                if(((addr + len) == sieve_start || addr == sieve_end) &&
                        (len + sieve_size) <= dset_contig->sieve_buf_size &&
                        dset_contig->sieve_dirty) {
                    /* Prepend to existing sieve buffer */
                    if((addr + len) == sieve_start) {
                        /* Move existing sieve information to correct location */
                        HDmemmove(dset_contig->sieve_buf + len, dset_contig->sieve_buf, dset_contig->sieve_size);

                        /* Copy in new information (must be first in sieve buffer) */
                        HDmemcpy(dset_contig->sieve_buf, buf, len);

                        /* Adjust sieve location */
                        dset_contig->sieve_loc = addr;

                    } /* end if */
                    /* Append to existing sieve buffer */
                    else {
                        /* Copy in new information */
                        HDmemcpy(dset_contig->sieve_buf + sieve_size, buf, len);
                    } /* end else */

                    /* Adjust sieve size */
                    dset_contig->sieve_size += len;

                    /* Update local copies of sieve information */
                    sieve_start = dset_contig->sieve_loc;
                    sieve_size = dset_contig->sieve_size;
                    sieve_end = sieve_start + sieve_size;
                } /* end if */
                /* Can't add the new data onto the existing sieve buffer */
                else {
                    /* Flush the sieve buffer if it's dirty */
                    if(dset_contig->sieve_dirty) {
                        /* Write to file */
                        if(H5F_block_write(file, H5FD_MEM_DRAW, sieve_start, sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = FALSE;
                    } /* end if */

                    /* Determine the new sieve buffer size & location */
                    dset_contig->sieve_loc = addr;

                    /* Make certain we don't read off the end of the file */
                    if(HADDR_UNDEF == (rel_eoa = H5F_get_eoa(file, H5FD_MEM_DRAW)))
                        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size")

                    /* Only need this when resizing sieve buffer */
                    max_data = store_contig->dset_size - dst_off;

                    /* Compute the size of the sieve buffer.
                     * Don't read off the end of the file, don't read past
                     * the end of the data element, and don't read more than
                     * the buffer size.
                     */
                    min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size); 
                    H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

                    /* Update local copies of sieve information */
                    sieve_start = dset_contig->sieve_loc;
                    sieve_size = dset_contig->sieve_size;
                    sieve_end = sieve_start + sieve_size;

                    /* Check if there is any point in reading the data from the file */
                    if(dset_contig->sieve_size > len) {
                        /* Read the new sieve buffer */
                        if(H5F_block_read(file, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size, udata->dxpl_id, dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed")
                    } /* end if */

                    /* Grab the data out of the buffer (must be first piece of data in buffer ) */
                    HDmemcpy(dset_contig->sieve_buf, buf, len);

                    /* Set sieve buffer dirty flag */
                    dset_contig->sieve_dirty = TRUE;
                } /* end else */
            } /* end else */
        } /* end else */
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_writevv_sieve_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv_cb
 *
 * Purpose:	Callback operator for H5D__contig_writevv().
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, Sept 30, 2010
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_writevv_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_writevv_ud_t *udata = (H5D_contig_writevv_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    /* Write data */
    if(H5F_block_write(udata->file, H5FD_MEM_DRAW, (udata->dset_addr + dst_off), len, udata->dxpl_id, (udata->wbuf + src_off)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_writevv_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv
 *
 * Purpose:	Writes some data vectors into a dataset from vectors into a
 *              buffer.  The address is the start of the dataset,
 *              relative to the base address for the file and the offsets and
 *              sequence lengths are in bytes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Friday, May 2, 2003
 *
 * Notes:
 *      Offsets in the sequences must be monotonically increasing
 *
 *-------------------------------------------------------------------------
 */
static ssize_t
H5D__contig_writevv(const H5D_io_info_t *io_info,
    size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_off_arr[],
    size_t mem_max_nseq, size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_off_arr[])
{
    H5D_dset_info_t dset_info;
    ssize_t ret_value = -1;             /* Return value (Size of sequence in bytes) */

    FUNC_ENTER_STATIC

    /* Check args */
    HDassert(io_info);
    HDassert(dset_curr_seq);
    HDassert(dset_len_arr);
    HDassert(dset_off_arr);
    HDassert(mem_curr_seq);
    HDassert(mem_len_arr);
    HDassert(mem_off_arr);

    dset_info = io_info->dsets_info[0];

    /* Check if data sieving is enabled */
    if(H5F_HAS_FEATURE(dset_info.dset->oloc.file, H5FD_FEAT_DATA_SIEVE)) {
        H5D_contig_writevv_sieve_ud_t udata;    /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.file = dset_info.dset->oloc.file;
        udata.dset_contig = &(dset_info.dset->shared->cache.contig);
        udata.store_contig = &(dset_info.store->contig);
        udata.wbuf = (const unsigned char *)dset_info.u.wbuf;
        udata.dxpl_id = io_info->raw_dxpl_id;

        /* Call generic sequence operation routine */
        if((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr,
                mem_max_nseq, mem_curr_seq, mem_len_arr, mem_off_arr,
                H5D__contig_writevv_sieve_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized sieve buffer write")
    } /* end if */
    else {
        H5D_contig_writevv_ud_t udata;     /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.file = dset_info.dset->oloc.file;
        udata.dset_addr = dset_info.store->contig.dset_addr;
        udata.wbuf = (const unsigned char *)dset_info.u.wbuf;
        udata.dxpl_id = io_info->raw_dxpl_id;

        /* Call generic sequence operation routine */
        if((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr,
                mem_max_nseq, mem_curr_seq, mem_len_arr, mem_off_arr,
                H5D__contig_writevv_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized read")
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}   /* end H5D__contig_writevv() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_flush
 *
 * Purpose:	Writes all dirty data to disk.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Monday, July 27, 2009
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_flush(H5D_t *dset, hid_t H5_ATTR_UNUSED dxpl_id)
{
    herr_t ret_value = SUCCEED;       /* Return value */

    FUNC_ENTER_STATIC

    /* Sanity check */
    HDassert(dset);

    /* Flush any data in sieve buffer - use the raw data dxpl since
       the one passed in is a metadata dxpl. */
    if(H5D__flush_sieve_buf(dset, H5AC_rawdata_dxpl_id) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTFLUSH, FAIL, "unable to flush sieve buffer")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_flush() */


/*-------------------------------------------------------------------------
 * Function:	H5D__contig_copy
 *
 * Purpose:	Copy contiguous storage raw data from SRC file to DST file.
 *
 * Return:	Non-negative on success, negative on failure.
 *
 * Programmer:  Quincey Koziol
 *	        Monday, November 21, 2005
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_copy(H5F_t *f_src, const H5O_storage_contig_t *storage_src,
    H5F_t *f_dst, H5O_storage_contig_t *storage_dst, H5T_t *dt_src,
    H5O_copy_t *cpy_info, hid_t dxpl_id)
{
    haddr_t     addr_src;               /* File offset in source dataset */
    haddr_t     addr_dst;               /* File offset in destination dataset */
    H5T_path_t  *tpath_src_mem = NULL, *tpath_mem_dst = NULL;   /* Datatype conversion paths */
    H5T_t       *dt_dst = NULL;         /* Destination datatype */
    H5T_t       *dt_mem = NULL;         /* Memory datatype */
    hid_t       tid_src = -1;           /* Datatype ID for source datatype */
    hid_t       tid_dst = -1;           /* Datatype ID for destination datatype */
    hid_t       tid_mem = -1;           /* Datatype ID for memory datatype */
    size_t      src_dt_size = 0;        /* Source datatype size */
    size_t      mem_dt_size = 0;        /* Memory datatype size */
    size_t      dst_dt_size = 0;        /* Destination datatype size */
    size_t      max_dt_size;            /* Max. datatype size */
    size_t      nelmts = 0;             /* Number of elements in buffer */
    size_t      src_nbytes;             /* Number of bytes to read from source */
    size_t      mem_nbytes;             /* Number of bytes to convert in memory */
    size_t      dst_nbytes;             /* Number of bytes to write to destination */
    hsize_t     total_src_nbytes;       /* Total number of bytes to copy */
    size_t      buf_size;               /* Size of copy buffer */
    void       *buf = NULL;             /* Buffer for copying data */
    void       *bkg = NULL;             /* Temporary buffer for copying data */
    void       *reclaim_buf = NULL;     /* Buffer for reclaiming data */
    H5S_t      *buf_space = NULL;       /* Dataspace describing buffer */
    hid_t       buf_sid = -1;           /* ID for buffer dataspace */
    hsize_t     buf_dim[1] = {0};       /* Dimension for buffer */
    hbool_t     is_vlen = FALSE;        /* Flag to indicate that VL type conversion should occur */
    hbool_t     fix_ref = FALSE;        /* Flag to indicate that ref values should be fixed */
    H5D_shared_t    *shared_fo = (H5D_shared_t *)cpy_info->shared_fo;  /* Pointer to the shared struct for dataset object */
    hbool_t     try_sieve = FALSE;      /* Try to get data from the sieve buffer */
    haddr_t     sieve_start = HADDR_UNDEF; /* Start location of sieve buffer */
    haddr_t     sieve_end = HADDR_UNDEF;    /* End locations of sieve buffer */
    herr_t      ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(f_src);
    HDassert(storage_src);
    HDassert(f_dst);
    HDassert(storage_dst);
    HDassert(dt_src);

    /* Allocate space for destination raw data */
    if(H5D__contig_alloc(f_dst, dxpl_id, storage_dst) < 0)
        HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to allocate contiguous storage")

    /* Set up number of bytes to copy, and initial buffer size */
    /* (actually use the destination size, which has been fixed up, if necessary) */
    total_src_nbytes = storage_dst->size;
    H5_CHECK_OVERFLOW(total_src_nbytes, hsize_t, size_t);
    buf_size = MIN(H5D_TEMP_BUF_SIZE, (size_t)total_src_nbytes);

    /* Create datatype ID for src datatype.  We may or may not use this ID,
     * but this ensures that the src datatype will be freed.
     */
    if((tid_src = H5I_register(H5I_DATATYPE, dt_src, FALSE)) < 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTREGISTER, FAIL, "unable to register source file datatype")

    /* If there's a VLEN source datatype, set up type conversion information */
    if(H5T_detect_class(dt_src, H5T_VLEN, FALSE) > 0) {
        /* create a memory copy of the variable-length datatype */
        if(NULL == (dt_mem = H5T_copy(dt_src, H5T_COPY_TRANSIENT)))
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to copy")
        if((tid_mem = H5I_register(H5I_DATATYPE, dt_mem, FALSE)) < 0) {
            H5T_close(dt_mem);
            HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "unable to register memory datatype")
        } /* end if */

        /* create variable-length datatype at the destinaton file */
        if(NULL == (dt_dst = H5T_copy(dt_src, H5T_COPY_TRANSIENT)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to copy")
        if(H5T_set_loc(dt_dst, f_dst, H5T_LOC_DISK) < 0) {
            H5T_close(dt_dst);
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "cannot mark datatype on disk")
        } /* end if */
        if((tid_dst = H5I_register(H5I_DATATYPE, dt_dst, FALSE)) < 0) {
            H5T_close(dt_dst);
            HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "unable to register destination file datatype")
        } /* end if */

        /* Set up the conversion functions */
        if(NULL == (tpath_src_mem = H5T_path_find(dt_src, dt_mem, NULL, NULL, dxpl_id, FALSE)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to convert between src and mem datatypes")
        if(NULL == (tpath_mem_dst = H5T_path_find(dt_mem, dt_dst, NULL, NULL, dxpl_id, FALSE)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to convert between mem and dst datatypes")

        /* Determine largest datatype size */
        if(0 == (src_dt_size = H5T_get_size(dt_src)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size")
        if(0 == (mem_dt_size = H5T_get_size(dt_mem)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size")
        max_dt_size = MAX(src_dt_size, mem_dt_size);
        if(0 == (dst_dt_size = H5T_get_size(dt_dst)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size")
        max_dt_size = MAX(max_dt_size, dst_dt_size);

        /* Set maximum number of whole elements that fit in buffer */
        if(0 == (nelmts = buf_size / max_dt_size))
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "element size too large")

        /* Set the number of bytes to transfer */
        src_nbytes = nelmts * src_dt_size;
        dst_nbytes = nelmts * dst_dt_size;
        mem_nbytes = nelmts * mem_dt_size;

        /* Adjust buffer size to be multiple of elements */
        buf_size = nelmts * max_dt_size;

        /* Create dataspace for number of elements in buffer */
        buf_dim[0] = nelmts;

        /* Create the space and set the initial extent */
        if(NULL == (buf_space = H5S_create_simple((unsigned)1, buf_dim, NULL)))
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create simple dataspace")

        /* Atomize */
        if((buf_sid = H5I_register(H5I_DATASPACE, buf_space, FALSE)) < 0) {
            H5S_close(buf_space);
            HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register dataspace ID")
        } /* end if */

        /* Set flag to do type conversion */
        is_vlen = TRUE;
    } /* end if */
    else {
        /* Check for reference datatype */
        if(H5T_get_class(dt_src, FALSE) == H5T_REFERENCE) {
            /* Need to fix values of references when copying across files */
            if(f_src != f_dst)
                fix_ref = TRUE;
        } /* end if */

        /* Set the number of bytes to read & write to the buffer size */
        src_nbytes = dst_nbytes = mem_nbytes = buf_size;
    } /* end else */

    /* Allocate space for copy buffer */
    HDassert(buf_size);
    if(NULL == (buf = H5FL_BLK_MALLOC(type_conv, buf_size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer")

    /* Need extra buffer for datatype conversions, to prevent stranding/leaking memory */
    if(is_vlen || fix_ref) {
        if(NULL == (reclaim_buf = H5FL_BLK_MALLOC(type_conv, buf_size)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer")

        /* allocate temporary bkg buff for data conversion */
        if(NULL == (bkg = H5FL_BLK_MALLOC(type_conv, buf_size)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer")
    } /* end if */

    /* Loop over copying data */
    addr_src = storage_src->addr;
    addr_dst = storage_dst->addr;

    /* If data sieving is enabled and the dataset is open in the file,
       set up to copy data out of the sieve buffer if deemed possible later */
    if(H5F_HAS_FEATURE(f_src, H5FD_FEAT_DATA_SIEVE) &&
       shared_fo && shared_fo->cache.contig.sieve_buf) {
        try_sieve = TRUE;
        sieve_start = shared_fo->cache.contig.sieve_loc;
        sieve_end = sieve_start + shared_fo->cache.contig.sieve_size;
    }

    while(total_src_nbytes > 0) {
        /* Check if we should reduce the number of bytes to transfer */
        if(total_src_nbytes < src_nbytes) {
            /* Adjust bytes to transfer */
            src_nbytes = (size_t)total_src_nbytes;

            /* Adjust dataspace describing buffer */
            if(is_vlen) {
                /* Adjust destination & memory bytes to transfer */
                nelmts = src_nbytes / src_dt_size;
                dst_nbytes = nelmts * dst_dt_size;
                mem_nbytes = nelmts * mem_dt_size;

                /* Adjust size of buffer's dataspace dimension */
                buf_dim[0] = nelmts;

                /* Adjust size of buffer's dataspace */
                if(H5S_set_extent_real(buf_space, buf_dim) < 0)
                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSET, FAIL, "unable to change buffer dataspace size")
            } /* end if */
            else
                /* Adjust destination & memory bytes to transfer */
                dst_nbytes = mem_nbytes = src_nbytes;
        } /* end if */

        /* If the entire copy is within the sieve buffer, copy data from the sieve buffer */
        if(try_sieve && (addr_src >= sieve_start) && ((addr_src + src_nbytes -1) < sieve_end)) {
            unsigned char *base_sieve_buf = shared_fo->cache.contig.sieve_buf + (addr_src - sieve_start);

            HDmemcpy(buf, base_sieve_buf, src_nbytes);
        } else
            /* Read raw data from source file - use raw dxpl because passed in one is metadata */
            if(H5F_block_read(f_src, H5FD_MEM_DRAW, addr_src, src_nbytes, H5AC_rawdata_dxpl_id, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "unable to read raw data")

        /* Perform datatype conversion, if necessary */
        if(is_vlen) {
            /* Convert from source file to memory */
            if(H5T_convert(tpath_src_mem, tid_src, tid_mem, nelmts, (size_t)0, (size_t)0, buf, bkg, dxpl_id) < 0)
                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "datatype conversion failed")

            /* Copy into another buffer, to reclaim memory later */
            HDmemcpy(reclaim_buf, buf, mem_nbytes);

            /* Set background buffer to all zeros */
            HDmemset(bkg, 0, buf_size);

            /* Convert from memory to destination file */
            if(H5T_convert(tpath_mem_dst, tid_mem, tid_dst, nelmts, (size_t)0, (size_t)0, buf, bkg, dxpl_id) < 0)
                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "datatype conversion failed")

            /* Reclaim space from variable length data */
            if(H5D_vlen_reclaim(tid_mem, buf_space, dxpl_id, reclaim_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_BADITER, FAIL, "unable to reclaim variable-length data")
        } /* end if */
        else if(fix_ref) {
            /* Check for expanding references */
            if(cpy_info->expand_ref) {
                size_t ref_count;

                /* Determine # of reference elements to copy */
                ref_count = src_nbytes / H5T_get_size(dt_src);

                /* Copy the reference elements */
                if(H5O_copy_expand_ref(f_src, buf, dxpl_id, f_dst, bkg, ref_count, H5T_get_ref_type(dt_src), cpy_info) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, FAIL, "unable to copy reference attribute")

                /* After fix ref, copy the new reference elements to the buffer to write out */
                HDmemcpy(buf, bkg,  buf_size);
            } /* end if */
            else
                /* Reset value to zero */
                HDmemset(buf, 0, src_nbytes);
        } /* end if */

        /* Write raw data to destination file - use raw dxpl because passed in one is metadata */
        if(H5F_block_write(f_dst, H5FD_MEM_DRAW, addr_dst, dst_nbytes, H5AC_rawdata_dxpl_id, buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "unable to write raw data")

        /* Adjust loop variables */
        addr_src += src_nbytes;
        addr_dst += dst_nbytes;
        total_src_nbytes -= src_nbytes;
    } /* end while */

done:
    if(buf_sid > 0 && H5I_dec_ref(buf_sid) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "can't decrement temporary dataspace ID")
    if(tid_src > 0 && H5I_dec_ref(tid_src) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't decrement temporary datatype ID")
    if(tid_dst > 0 && H5I_dec_ref(tid_dst) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't decrement temporary datatype ID")
    if(tid_mem > 0 && H5I_dec_ref(tid_mem) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't decrement temporary datatype ID")
    if(buf)
        buf = H5FL_BLK_FREE(type_conv, buf);
    if(reclaim_buf)
        reclaim_buf = H5FL_BLK_FREE(type_conv, reclaim_buf);
    if(bkg)
        bkg = H5FL_BLK_FREE(type_conv, bkg);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_copy() */