path: root/src/H5Ocopy.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * 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://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*-------------------------------------------------------------------------
 *
 * Created:     H5Ocopy.c
 *
 * Purpose:     Object copying routines.
 *
 *-------------------------------------------------------------------------
 */

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

#include "H5Omodule.h" /* This source code file is part of the H5O module */

/***********/
/* Headers */
/***********/
#include "H5private.h"   /* Generic Functions                        */
#include "H5Aprivate.h"  /* Attributes                               */
#include "H5CXprivate.h" /* API Contexts                             */
#include "H5Eprivate.h"  /* Error handling                           */
#include "H5FLprivate.h" /* Free lists                               */
#include "H5Iprivate.h"  /* IDs                                      */
#include "H5HGprivate.h" /* Global Heaps                             */
#include "H5FOprivate.h" /* File objects                             */
#include "H5Lprivate.h"  /* Links                                    */
#include "H5MFprivate.h" /* File memory management                   */
#include "H5MMprivate.h" /* Memory management                        */
#include "H5Opkg.h"      /* Object headers                           */
#include "H5Pprivate.h"  /* Property lists                           */
#include "H5VLprivate.h" /* Virtual Object Layer                     */

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

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

/* Key object for skiplist of committed datatypes */
typedef struct H5O_copy_search_comm_dt_key_t {
    H5T_t        *dt;     /* Datatype */
    unsigned long fileno; /* File number */
} H5O_copy_search_comm_dt_key_t;

/* Callback struct for building a list of committed datatypes */
typedef struct H5O_copy_search_comm_dt_ud_t {
    H5SL_t    *dst_dt_list;  /* Skip list of committed datatypes */
    H5G_loc_t *dst_root_loc; /* Starting location for iteration */
    H5O_loc_t  obj_oloc;     /* Object location (for attribute iteration callback) */
} H5O_copy_search_comm_dt_ud_t;

/********************/
/* Package Typedefs */
/********************/

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

static herr_t H5O__copy_free_addrmap_cb(void *item, void *key, void *op_data);
static herr_t H5O__copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out*/,
                                    H5O_copy_t *cpy_info, H5O_type_t *obj_type, void **udata);
static herr_t H5O__copy_header(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out*/, hid_t ocpypl_id,
                               hid_t lcpl_id);
static herr_t H5O__copy_obj(H5G_loc_t *src_loc, H5G_loc_t *dst_loc, const char *dst_name, hid_t ocpypl_id,
                            hid_t lcpl_id);
static herr_t H5O__copy_free_comm_dt_cb(void *item, void *key, void *op_data);
static int    H5O__copy_comm_dt_cmp(const void *dt1, const void *dt2);
static herr_t H5O__copy_search_comm_dt_cb(hid_t group, const char *name, const H5L_info2_t *linfo,
                                          void *udata);
static htri_t H5O__copy_search_comm_dt(H5F_t *file_src, H5O_t *oh_src, H5O_loc_t *oloc_dst /*in, out*/,
                                       H5O_copy_t *cpy_info);
static herr_t H5O__copy_insert_comm_dt(H5F_t *file_src, H5O_t *oh_src, H5O_loc_t *oloc_dst,
                                       H5O_copy_t *cpy_info);

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

/* Declare a free list to manage the H5O_addr_map_t struct */
H5FL_DEFINE(H5O_addr_map_t);

/* Declare a free list to manage the H5O_copy_search_comm_dt_key_t struct */
H5FL_DEFINE(H5O_copy_search_comm_dt_key_t);

/* Declare a free list to manage haddr_t variables */
H5FL_DEFINE(haddr_t);

/*****************************/
/* Library Private Variables */
/*****************************/

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

/*-------------------------------------------------------------------------
 * Function:    H5O__copy
 *
 * Purpose:     Private version of H5Ocopy
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5O__copy(const H5G_loc_t *loc, const char *src_name, H5G_loc_t *dst_loc, const char *dst_name,
          hid_t ocpypl_id, hid_t lcpl_id)
{
    H5G_loc_t  src_loc;             /* Source object group location */
    H5G_name_t src_path;            /* Opened source object hier. path */
    H5O_loc_t  src_oloc;            /* Opened source object object location */
    bool       dst_exists;          /* Does destination name exist already? */
    bool       loc_found = false;   /* Location at 'name' found */
    bool       obj_open  = false;   /* Entry at 'name' found */
    herr_t     ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check arguments */
    assert(loc);
    assert(src_name && *src_name);
    assert(dst_loc);
    assert(dst_name && *dst_name);

    /* Check if destination name already exists */
    dst_exists = false;
    if (H5L_exists_tolerant(dst_loc, dst_name, &dst_exists) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "unable to check if destination name exists");
    if (dst_exists)
        HGOTO_ERROR(H5E_OHDR, H5E_EXISTS, FAIL, "destination object already exists");

    /* Set up opened group location to fill in */
    src_loc.oloc = &src_oloc;
    src_loc.path = &src_path;
    H5G_loc_reset(&src_loc);

    /* Find the source object to copy */
    if (H5G_loc_find(loc, src_name, &src_loc /*out*/) < 0)
        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "source object not found");
    loc_found = true;

    /* Open source object's object header */
    if (H5O_open(&src_oloc) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open object");
    obj_open = true;

    /* Do the actual copying of the object */
    if (H5O__copy_obj(&src_loc, dst_loc, dst_name, ocpypl_id, lcpl_id) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy object");

done:
    if (loc_found && H5G_loc_free(&src_loc) < 0)
        HDONE_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "can't free location");
    if (obj_open && H5O_close(&src_oloc, NULL) < 0)
        HDONE_ERROR(H5E_OHDR, H5E_CLOSEERROR, FAIL, "unable to release object header");

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy() */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_header_real
 *
 * Purpose:     Copy header object from one location to another using
 *              pre-copy, copy, and post-copy callbacks for each message
 *              type.
 *
 *              The source header object is compressed into a single chunk
 *              (since we know how big it is) and any continuation messages
 *              are converted into NULL messages.
 *
 *              By default, NULL messages are not copied.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out*/, H5O_copy_t *cpy_info,
                      H5O_type_t *obj_type, void **udata /*out*/)
{
    H5O_addr_map_t *addr_map = NULL; /* Address mapping of object copied */
    H5O_t          *oh_src   = NULL; /* Object header for source object */
    H5O_t          *oh_dst   = NULL; /* Object header for destination object */
    unsigned        mesgno   = 0;
    haddr_t         addr_new = HADDR_UNDEF;
    bool           *deleted  = NULL; /* Array of flags indicating whether messages should be copied */
    bool        inserted = false; /* Whether the destination object header has been inserted into the cache */
    size_t      null_msgs;        /* Number of NULL messages found in each loop */
    size_t      orig_dst_msgs;    /* Original # of messages in dest. object */
    H5O_mesg_t *mesg_src;         /* Message in source object header */
    H5O_mesg_t *mesg_dst;         /* Message in destination object header */
    const H5O_msg_class_t *copy_type;        /* Type of message to use for copying */
    const H5O_obj_class_t *obj_class = NULL; /* Type of object we are copying */
    void                  *cpy_udata = NULL; /* User data for passing to message callbacks */
    uint64_t               dst_oh_size;      /* Total size of the destination OH */
    size_t                 dst_oh_null;      /* Size of the null message to add to destination OH */
    size_t                 dst_oh_gap;       /* Size of the gap in chunk #0 of destination OH */
    uint8_t               *current_pos;      /* Current position in destination image */
    size_t                 msghdr_size;
    herr_t                 ret_value = SUCCEED;

    FUNC_ENTER_PACKAGE_TAG(oloc_src->addr)

    assert(oloc_src);
    assert(oloc_src->file);
    assert(H5_addr_defined(oloc_src->addr));
    assert(oloc_dst->file);
    assert(cpy_info);

    /* Get pointer to object class for this object */
    if (NULL == (obj_class = H5O__obj_class(oloc_src)))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to determine object type");

    /* Set the pointer to the shared struct for the object if opened in the file */
    cpy_info->shared_fo = H5FO_opened(oloc_src->file, oloc_src->addr);

    /* Get source object header */
    if (NULL == (oh_src = H5O_protect(oloc_src, H5AC__READ_ONLY_FLAG, false)))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTPROTECT, FAIL, "unable to load object header");

    /* Retrieve user data for particular type of object to copy */
    if (obj_class->get_copy_file_udata && (NULL == (cpy_udata = (obj_class->get_copy_file_udata)())))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to retrieve copy user data");

    /* If we are merging committed datatypes, check for a match in the destination
     * file now */
    if (cpy_info->merge_comm_dt && obj_class->type == H5O_TYPE_NAMED_DATATYPE) {
        unsigned long fileno_src; /* fileno for source file */
        unsigned long fileno_dst; /* fileno for destination file */
        htri_t        merge;      /* Whether we found a match in the destination file */

        /* Check if the source and dest file are the same.  If so, just return
         * the source object address */
        H5F_GET_FILENO(oloc_src->file, fileno_src);
        H5F_GET_FILENO(oloc_dst->file, fileno_dst);
        if (fileno_src == fileno_dst) {
            merge          = true;
            oloc_dst->addr = oloc_src->addr;
        } /* end if */
        else
            /* Search for a matching committed datatype, building the list if
             * necessary */
            if ((merge = H5O__copy_search_comm_dt(oloc_src->file, oh_src, oloc_dst, cpy_info)) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't search for matching committed datatype");

        if (merge) {
            /* Found a match, add to skip list and exit */
            /* Allocate space for the address mapping of the object copied */
            if (NULL == (addr_map = H5FL_MALLOC(H5O_addr_map_t)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

            /* Insert the address mapping for the found object into the copied
             * list */
            addr_map->src_obj_pos.fileno = fileno_src;
            addr_map->src_obj_pos.addr   = oloc_src->addr;
            addr_map->dst_addr           = oloc_dst->addr;
            addr_map->is_locked          = true; /* We've locked the object currently */
            addr_map->inc_ref_count      = 0;    /* Start with no additional ref counts to add */
            addr_map->obj_class          = obj_class;
            addr_map->udata              = cpy_udata;

            /* Insert into skip list */
            if (H5SL_insert(cpy_info->map_list, addr_map, &(addr_map->src_obj_pos)) < 0) {
                addr_map = H5FL_FREE(H5O_addr_map_t, addr_map);
                HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");
            } /* end if */

            HGOTO_DONE(SUCCEED);
        } /* end if */
    }     /* end if */

    /* Flush any dirty messages in source object header to update the header chunks */
    if (H5O__flush_msgs(oloc_src->file, oh_src) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTFLUSH, FAIL, "unable to flush object header messages");

    /* Allocate the destination object header and fill in header fields */
    if (NULL == (oh_dst = H5FL_CALLOC(H5O_t)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Initialize header information */
    oh_dst->version = oh_src->version;

    /* Version bounds check for destination object header */
    if (oh_dst->version > H5O_obj_ver_bounds[H5F_HIGH_BOUND(oloc_dst->file)])
        HGOTO_ERROR(H5E_OHDR, H5E_BADRANGE, FAIL, "destination object header version out of bounds");

    oh_dst->flags          = oh_src->flags;
    oh_dst->link_msgs_seen = oh_src->link_msgs_seen;
    oh_dst->attr_msgs_seen = oh_src->attr_msgs_seen;
    oh_dst->sizeof_size    = H5F_SIZEOF_SIZE(oloc_dst->file);
    oh_dst->sizeof_addr    = H5F_SIZEOF_ADDR(oloc_dst->file);
    oh_dst->swmr_write     = !!(H5F_INTENT(oloc_dst->file) & H5F_ACC_SWMR_WRITE);

    /* Copy time fields */
    oh_dst->atime = oh_src->atime;
    oh_dst->mtime = oh_src->mtime;
    oh_dst->ctime = oh_src->ctime;
    oh_dst->btime = oh_src->btime;

    /* Copy attribute storage information */
    oh_dst->max_compact = oh_src->max_compact;
    oh_dst->min_dense   = oh_src->min_dense;

    /* Create object header proxy if doing SWMR writes */
    if (oh_dst->swmr_write) {
        /* Create virtual entry, for use as proxy */
        if (NULL == (oh_dst->proxy = H5AC_proxy_entry_create()))
            HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "can't create object header proxy");
    } /* end if */
    else
        oh_dst->proxy = NULL;

    /* Initialize size of chunk array.  Start off with zero chunks so this field
     * is consistent with the current state of the chunk array.  This is
     * important if an error occurs.
     */
    oh_dst->alloc_nchunks = oh_dst->nchunks = 0;

    /* Allocate memory for the chunk array - always start with 1 chunk */
    if (NULL == (oh_dst->chunk = H5FL_SEQ_MALLOC(H5O_chunk_t, (size_t)1)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Update number of allocated chunks.  There are still no chunks used. */
    oh_dst->alloc_nchunks = 1;

    /* Allocate memory for "deleted" array.  This array marks the message in
     * the source that shouldn't be copied to the destination.
     */
    if (NULL == (deleted = (bool *)H5MM_malloc(sizeof(bool) * oh_src->nmesgs)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
    memset(deleted, false, sizeof(bool) * oh_src->nmesgs);

    /* "pre copy" pass over messages, to gather information for actual message copy operation
     * (for messages which depend on information from other messages)
     * Keep track of how many NULL or deleted messages we find (or create)
     */
    null_msgs = 0;
    for (mesgno = 0; mesgno < oh_src->nmesgs; mesgno++) {
        /* Set up convenience variables */
        mesg_src = &(oh_src->mesg[mesgno]);

        /* Sanity check */
        assert(!mesg_src->dirty); /* Should be cleared by earlier call to flush messages */

        /* Get message class to operate on */
        copy_type = mesg_src->type;

        /* Check for continuation message; these are converted to NULL
         * messages because the destination OH will have only one chunk
         */
        if (H5O_CONT_ID == mesg_src->type->id || H5O_NULL_ID == mesg_src->type->id) {
            deleted[mesgno] = true;
            ++null_msgs;
            copy_type = H5O_MSG_NULL;
        } /* end if */
        assert(copy_type);

        if (copy_type->pre_copy_file) {
            /* Decode the message if necessary. */
            H5O_LOAD_NATIVE(oloc_src->file, 0, oh_src, mesg_src, FAIL)

            /* Save destination file pointer in cpy_info so that it can be used
               in the pre_copy_file callback to obtain the destination file's
               high bound.  The high bound is used to index into the corresponding
               message's array of versions for doing version bounds check. */
            cpy_info->file_dst = oloc_dst->file;

            /* Perform "pre copy" operation on message */
            if ((copy_type->pre_copy_file)(oloc_src->file, mesg_src->native, &(deleted[mesgno]), cpy_info,
                                           cpy_udata) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL,
                            "unable to perform 'pre copy' operation on message");

            /* Check if the message should be deleted in the destination */
            if (deleted[mesgno])
                /* Mark message as deleted */
                ++null_msgs;
        } /* end if(copy_type->pre_copy_file) */
    }     /* end for */

    /* Initialize size of message list.  It may or may not include the NULL messages
     * detected above.
     */
    if (cpy_info->preserve_null)
        oh_dst->alloc_nmesgs = oh_dst->nmesgs = oh_src->nmesgs;
    else
        oh_dst->alloc_nmesgs = oh_dst->nmesgs = (oh_src->nmesgs - null_msgs);

    /* Allocate memory for destination message array */
    if (oh_dst->alloc_nmesgs > 0)
        if (NULL == (oh_dst->mesg = H5FL_SEQ_CALLOC(H5O_mesg_t, oh_dst->alloc_nmesgs)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* "copy" pass over messages, to perform main message copying */
    null_msgs = 0;
    for (mesgno = 0; mesgno < oh_dst->nmesgs; mesgno++) {
        /* Skip any deleted or NULL messages in the source unless the
         * preserve_null flag is set
         */
        if (false == cpy_info->preserve_null) {
            while (deleted[mesgno + null_msgs]) {
                ++null_msgs;
                assert(mesgno + null_msgs < oh_src->nmesgs);
            } /* end while */
        }     /* end if */

        /* Set up convenience variables */
        mesg_src = &(oh_src->mesg[mesgno + null_msgs]);
        mesg_dst = &(oh_dst->mesg[mesgno]);

        /* Initialize non-zero components of destination message */
        mesg_dst->crt_idx  = mesg_src->crt_idx;
        mesg_dst->flags    = mesg_src->flags;
        mesg_dst->raw_size = mesg_src->raw_size;
        mesg_dst->type     = mesg_src->type;

        /* If we're preserving deleted messages, set their types to 'NULL'
         * in the destination.
         */
        if (cpy_info->preserve_null && deleted[mesgno]) {
            mesg_dst->type  = H5O_MSG_NULL;
            mesg_dst->flags = 0;
            mesg_dst->dirty = true;
        } /* end if */

        /* Check for message class to operate on */
        /* (Use destination message, in case the message has been removed (i.e
         *      converted to a nil message) in the destination -QAK)
         */
        copy_type = mesg_dst->type;
        assert(copy_type);

        /* copy this message into destination file */
        if (copy_type->copy_file) {
            bool     recompute_size; /* Whether copy_file callback created a shared message */
            unsigned mesg_flags;     /* Message flags */

            /* Decode the message if necessary. */
            H5O_LOAD_NATIVE(oloc_src->file, 0, oh_src, mesg_src, FAIL)

            /* Get destination message flags, and unset shared and shareable
             * flags.  mesg_dst->flags will contain the original flags for now.
             */
            mesg_flags = (unsigned)mesg_dst->flags & ~H5O_MSG_FLAG_SHARED & ~H5O_MSG_FLAG_SHAREABLE;

            /* Copy the source message */
            recompute_size = false;
            if (NULL == (mesg_dst->native =
                             H5O__msg_copy_file(copy_type, oloc_src->file, mesg_src->native, oloc_dst->file,
                                                &recompute_size, &mesg_flags, cpy_info, cpy_udata)))
                HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy object header message");

            /* Check if the sharing state changed, and recompute the size if so
             */
            if (!(mesg_flags & H5O_MSG_FLAG_SHARED) != !(mesg_dst->flags & H5O_MSG_FLAG_SHARED))
                recompute_size = true;

            /* Set destination message flags */
            mesg_dst->flags = (uint8_t)mesg_flags;

            /* Recompute message's size */
            /* (its sharing status or one of its components (for attributes)
             *  could have changed)
             */
            if (recompute_size)
                mesg_dst->raw_size = H5O_ALIGN_OH(
                    oh_dst, H5O_msg_raw_size(oloc_dst->file, mesg_dst->type->id, false, mesg_dst->native));

            /* Mark the message in the destination as dirty, so it'll get encoded when the object header is
             * flushed */
            mesg_dst->dirty = true;
        } /* end if (mesg_src->type->copy_file) */
    }     /* end of mesgno loop */

    /* Allocate the destination header and copy any messages that didn't have
     * copy callbacks.  They get copied directly from the source image to the
     * destination image.
     */

    /* Calculate how big the destination object header will be on disk.
     * This isn't necessarily the same size as the original.
     */

    /* Compute space for messages. */
    dst_oh_size = 0;
    for (mesgno = 0; mesgno < oh_dst->nmesgs; mesgno++) {
        dst_oh_size += (uint64_t)H5O_SIZEOF_MSGHDR_OH(oh_dst);
        dst_oh_size += oh_dst->mesg[mesgno].raw_size;
    } /* end for */

    /* Check if we need to determine correct value for chunk #0 size bits */
    if (oh_dst->version > H5O_VERSION_1) {
        /* Reset destination object header's "chunk 0 size" flags */
        oh_dst->flags = (uint8_t)(oh_dst->flags & ~H5O_HDR_CHUNK0_SIZE);

        /* Determine correct value for chunk #0 size bits */
        if (dst_oh_size > 4294967295)
            oh_dst->flags |= H5O_HDR_CHUNK0_8;
        else if (dst_oh_size > 65535)
            oh_dst->flags |= H5O_HDR_CHUNK0_4;
        else if (dst_oh_size > 255)
            oh_dst->flags |= H5O_HDR_CHUNK0_2;
    } /* end if */

    /* Check if the chunk's data portion is too small */
    dst_oh_gap = dst_oh_null = 0;
    if (dst_oh_size < H5O_MIN_SIZE) {
        size_t delta = (size_t)(H5O_MIN_SIZE - dst_oh_size); /* Delta in chunk size needed */

        /* Sanity check */
        assert((oh_dst->flags & H5O_HDR_CHUNK0_SIZE) == H5O_HDR_CHUNK0_1);

        /* Determine whether to create gap or NULL message */
        if ((oh_dst->version > H5O_VERSION_1) && (delta < H5O_SIZEOF_MSGHDR_OH(oh_dst)))
            dst_oh_gap = delta;
        else {
            /* NULL message must be at least size of message header */
            if (delta < H5O_SIZEOF_MSGHDR_OH(oh_dst))
                delta = H5O_SIZEOF_MSGHDR_OH(oh_dst);

            dst_oh_null = delta;
        }

        /* Increase destination object header size */
        dst_oh_size += delta;

        /* Sanity check */
        assert(dst_oh_size <= 255);
    } /* end if */

    /* Add in destination's object header size now */
    dst_oh_size += (uint64_t)H5O_SIZEOF_HDR(oh_dst);

    /* Allocate space for chunk in destination file */
    if (HADDR_UNDEF ==
        (oh_dst->chunk[0].addr = H5MF_alloc(oloc_dst->file, H5FD_MEM_OHDR, (hsize_t)dst_oh_size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for object header");
    addr_new = oh_dst->chunk[0].addr;

    /* Create memory image for the new chunk */
    /* Note: we use calloc() instead of malloc() here because older versions of
     *  some messages don't initialize "unused" bytes and because we want to
     *  write out the same version of the object header and older versions of
     *  object headers aligned messages.  In both those situations, it's
     *  complex and error-prone to determine all the proper ways/places to
     *  clear to zero bytes, so we just set the buffer to zero's here.
     *  (QAK - 2010/08/17)
     */
    if (NULL == (oh_dst->chunk[0].image = H5FL_BLK_CALLOC(chunk_image, (size_t)dst_oh_size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Set dest. chunk information */
    oh_dst->chunk[0].size = (size_t)dst_oh_size;
    oh_dst->chunk[0].gap  = dst_oh_gap;

    /* Update size of chunk array.  The destination now has one chunk. */
    oh_dst->nchunks = 1;

    /* Set up raw pointers and copy messages that didn't need special
     * treatment.  This has to happen after the destination header has been
     * allocated.
     */
    assert(H5O_SIZEOF_MSGHDR_OH(oh_src) == H5O_SIZEOF_MSGHDR_OH(oh_dst));
    msghdr_size = H5O_SIZEOF_MSGHDR_OH(oh_dst);

    current_pos = oh_dst->chunk[0].image;

    /* Write the magic number for versions > 1 and skip the rest of the
     * header.  This will be written when the header is flushed to disk.
     */
    if (oh_dst->version > H5O_VERSION_1)
        H5MM_memcpy(current_pos, H5O_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC);
    current_pos += H5O_SIZEOF_HDR(oh_dst) - H5O_SIZEOF_CHKSUM_OH(oh_dst);

    /* Loop through destination messages, updating their "raw" info */
    null_msgs = 0;
    for (mesgno = 0; mesgno < oh_dst->nmesgs; mesgno++) {
        /* Skip any deleted or NULL messages in the source unless the
         * preserve_null flag is set.
         */
        if (false == cpy_info->preserve_null) {
            while (deleted[mesgno + null_msgs]) {
                ++null_msgs;
                assert(mesgno + null_msgs < oh_src->nmesgs);
            } /* end while */
        }     /* end if */

        /* Set up convenience variables */
        mesg_src = &(oh_src->mesg[mesgno + null_msgs]);
        mesg_dst = &(oh_dst->mesg[mesgno]);

        /* Copy each message that wasn't dirtied above */
        if (!mesg_dst->dirty)
            /* Copy the message header plus the message's raw data. */
            H5MM_memcpy(current_pos, mesg_src->raw - msghdr_size, msghdr_size + mesg_src->raw_size);

        /* Set message's raw pointer to destination chunk's new "image" */
        mesg_dst->raw = current_pos + msghdr_size;

        /* Move to location where next message should go */
        current_pos += mesg_dst->raw_size + msghdr_size;
    } /* end for */

    /* Save this in case more messages are added during NULL message checking */
    orig_dst_msgs = oh_dst->nmesgs;

    /* Check if we need to add a NULL message to this header */
    if (dst_oh_null > 0) {
        size_t null_idx; /* Index of new NULL message */

        /* Make sure we have enough space for new NULL message */
        if (oh_dst->nmesgs + 1 > oh_dst->alloc_nmesgs)
            if (H5O__alloc_msgs(oh_dst, (size_t)1) < 0)
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate more space for messages");

        /* Create null message for [rest of] space in new chunk */
        /* (account for chunk's magic # & checksum) */
        null_idx                        = oh_dst->nmesgs++;
        oh_dst->mesg[null_idx].type     = H5O_MSG_NULL;
        oh_dst->mesg[null_idx].dirty    = true;
        oh_dst->mesg[null_idx].native   = NULL;
        oh_dst->mesg[null_idx].raw      = current_pos + msghdr_size;
        oh_dst->mesg[null_idx].raw_size = dst_oh_null - msghdr_size;
        oh_dst->mesg[null_idx].chunkno  = 0;
    } /* end if */

    /* Make sure we filled the chunk, except for room at the end for a checksum */
    assert(current_pos + dst_oh_gap + dst_oh_null + H5O_SIZEOF_CHKSUM_OH(oh_dst) ==
           (size_t)dst_oh_size + oh_dst->chunk[0].image);

    /* Set the dest. object location to the first chunk address */
    assert(H5_addr_defined(addr_new));
    oloc_dst->addr = addr_new;

    /* If we are merging committed datatypes and this is a committed datatype, insert
     * the copied datatype into the list of committed datatypes in the target file.
     */
    if (cpy_info->merge_comm_dt && obj_class->type == H5O_TYPE_NAMED_DATATYPE)
        if (H5O__copy_insert_comm_dt(oloc_src->file, oh_src, oloc_dst, cpy_info) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't insert committed datatype into destination list");

    /* Allocate space for the address mapping of the object copied */
    if (NULL == (addr_map = H5FL_MALLOC(H5O_addr_map_t)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Insert the address mapping for the new object into the copied list */
    /* (Do this here, because "post copy" possibly checks it) */
    H5F_GET_FILENO(oloc_src->file, addr_map->src_obj_pos.fileno);
    addr_map->src_obj_pos.addr = oloc_src->addr;
    addr_map->dst_addr         = oloc_dst->addr;
    addr_map->is_locked        = true; /* We've locked the object currently */
    addr_map->inc_ref_count    = 0;    /* Start with no additional ref counts to add */
    addr_map->obj_class        = obj_class;
    addr_map->udata            = cpy_udata;

    /* Insert into skip list */
    if (H5SL_insert(cpy_info->map_list, addr_map, &(addr_map->src_obj_pos)) < 0) {
        addr_map = H5FL_FREE(H5O_addr_map_t, addr_map);
        HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");
    } /* end if */

    /* "post copy" loop over messages, to fix up any messages which require a complete
     * object header for destination object
     */
    null_msgs = 0;
    for (mesgno = 0; mesgno < orig_dst_msgs; mesgno++) {
        /* Skip any deleted or NULL messages in the source unless the
         * preserve_null flag is set
         */
        if (false == cpy_info->preserve_null) {
            while (deleted[mesgno + null_msgs]) {
                ++null_msgs;
                assert(mesgno + null_msgs < oh_src->nmesgs);
            } /* end while */
        }     /* end if */

        /* Set up convenience variables */
        mesg_src = &(oh_src->mesg[mesgno + null_msgs]);
        mesg_dst = &(oh_dst->mesg[mesgno]);

        /* Check for message class to operate on */
        /* (Use destination message, in case the message has been removed (i.e
         *      converted to a nil message) in the destination -QAK)
         */
        copy_type = mesg_dst->type;
        assert(copy_type);

        if (copy_type->post_copy_file && mesg_src->native) {
            unsigned mesg_flags; /* Message flags */

            /* Sanity check destination message */
            assert(mesg_dst->type == mesg_src->type);
            assert(mesg_dst->native);

            /* Get destination message flags.   mesg_dst->flags will contain the
             * original flags for now. */
            mesg_flags = (unsigned)mesg_dst->flags;

            /* the object header is needed in the post copy for shared message */
            cpy_info->oh_dst = oh_dst;

            /* Perform "post copy" operation on message */
            if ((copy_type->post_copy_file)(oloc_src, mesg_src->native, oloc_dst, mesg_dst->native,
                                            &mesg_flags, cpy_info) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL,
                            "unable to perform 'post copy' operation on message");

            /* Verify that the flags did not change */
            assert(mesg_flags == (unsigned)mesg_dst->flags);
        } /* end if */
    }     /* end for */

    /* Indicate that the destination address will no longer be locked */
    addr_map->is_locked = false;

    /* Increment object header's reference count, if any descendents have created links to this object */
    if (addr_map->inc_ref_count) {
        H5_CHECK_OVERFLOW(addr_map->inc_ref_count, hsize_t, unsigned);
        oh_dst->nlink += (unsigned)addr_map->inc_ref_count;
    } /* end if */

    /* Retag all copied metadata to apply the destination object's tag */
    if (H5AC_retag_copied_metadata(oloc_dst->file, oloc_dst->addr) < 0)
        HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "unable to re-tag metadata entries");

    /* Set metadata tag for destination object's object header */
    H5_BEGIN_TAG(oloc_dst->addr)

    /* Insert destination object header in cache */
    if (H5AC_insert_entry(oloc_dst->file, H5AC_OHDR, oloc_dst->addr, oh_dst, H5AC__NO_FLAGS_SET) < 0)
        HGOTO_ERROR_TAG(H5E_OHDR, H5E_CANTINSERT, FAIL, "unable to cache object header");
    oh_dst   = NULL;
    inserted = true;

    /* Reset metadata tag */
    H5_END_TAG

    /* Set obj_type and udata, if requested */
    if (obj_type) {
        assert(udata);
        *obj_type = obj_class->type;
        *udata    = cpy_udata;
    } /* end if */

done:
    /* Free deleted array */
    if (deleted)
        H5MM_free(deleted);

    /* Release pointer to source object header and its derived objects */
    if (oh_src && H5O_unprotect(oloc_src, oh_src, H5AC__NO_FLAGS_SET) < 0)
        HDONE_ERROR(H5E_OHDR, H5E_CANTUNPROTECT, FAIL, "unable to release object header");

    /* Free destination object header on failure */
    if (ret_value < 0) {
        if (oh_dst && !inserted) {
            if (H5O__free(oh_dst, true) < 0)
                HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to destroy object header data");
            if (H5O_loc_reset(oloc_dst) < 0)
                HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to destroy object header data");
        } /* end if */

        if (addr_map == NULL && cpy_udata) {
            if (obj_class && obj_class->free_copy_file_udata)
                obj_class->free_copy_file_udata(cpy_udata);
        } /* end if */
    }

    FUNC_LEAVE_NOAPI_TAG(ret_value)
} /* end H5O__copy_header_real() */

/*-------------------------------------------------------------------------
 * Function:    H5O_copy_header_map
 *
 * Purpose:     Copy header object from one location to another, detecting
 *              already mapped objects, etc.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5O_copy_header_map(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out*/, H5O_copy_t *cpy_info,
                    bool inc_depth, H5O_type_t *obj_type, void **udata /*out*/)
{
    H5O_addr_map_t *addr_map = NULL; /* Address mapping of object copied */
    H5_obj_t        src_obj_pos;     /* Position of source object */
    bool            inc_link;        /* Whether to increment the link count for the object */
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(FAIL)

    /* Sanity check */
    assert(oloc_src);
    assert(oloc_src->file);
    assert(oloc_dst);
    assert(oloc_dst->file);
    assert(cpy_info);

    /* Create object "position" struct */
    H5F_GET_FILENO(oloc_src->file, src_obj_pos.fileno);
    src_obj_pos.addr = oloc_src->addr;

    /* Search for the object in the skip list of copied objects */
    addr_map = (H5O_addr_map_t *)H5SL_search(cpy_info->map_list, &src_obj_pos);

    /* Check if address is already in list of objects copied */
    if (addr_map == NULL) {
        /* Copy object for the first time */

        /* Check for incrementing the depth of copy */
        /* (Can't do this for all copies, since committed datatypes should always be copied) */
        if (inc_depth)
            cpy_info->curr_depth++;

        /* Copy object referred to */
        if (H5O__copy_header_real(oloc_src, oloc_dst, cpy_info, obj_type, udata) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy object");

        /* Check for incrementing the depth of copy */
        if (inc_depth)
            cpy_info->curr_depth--;

        /* When an object is copied for the first time, increment it's link */
        inc_link = true;

        /* indicate that a new object is created */
        ret_value++;
    } /* end if */
    else {
        /* Object has already been copied, set its address in destination file */
        oloc_dst->addr = addr_map->dst_addr;

        /* Return saved obj_type and udata, if requested */
        if (obj_type) {
            assert(udata);
            *obj_type = addr_map->obj_class->type;
            *udata    = addr_map->udata;
        } /* end if */

        /* If the object is locked currently (because we are copying a group
         * hierarchy and this is a link to a group higher in the hierarchy),
         * increment it's deferred reference count instead of incrementing the
         * reference count now.
         */
        if (addr_map->is_locked) {
            addr_map->inc_ref_count++;
            inc_link = false;
        } /* end if */
        else
            inc_link = true;
    } /* end else */

    /* Increment destination object's link count, if allowed */
    if (inc_link)
        if (H5O_link(oloc_dst, 1) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to increment object link count");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O_copy_header_map() */

/*--------------------------------------------------------------------------
 NAME
    H5O__copy_free_addrmap_cb
 PURPOSE
    Internal routine to free address maps from the skip list for copying objects
 USAGE
    herr_t H5O__copy_free_addrmap_cb(item, key, op_data)
        void *item;             IN/OUT: Pointer to addr
        void *key;              IN/OUT: (unused)
        void *op_data;          IN: (unused)
 RETURNS
    Returns zero on success, negative on failure.
 DESCRIPTION
        Releases the memory for the address.
 GLOBAL VARIABLES
 COMMENTS, BUGS, ASSUMPTIONS
 EXAMPLES
 REVISION LOG
--------------------------------------------------------------------------*/
static herr_t
H5O__copy_free_addrmap_cb(void *_item, void H5_ATTR_UNUSED *key, void H5_ATTR_UNUSED *op_data)
{
    H5O_addr_map_t *item = (H5O_addr_map_t *)_item;

    FUNC_ENTER_PACKAGE_NOERR

    assert(item);

    /* Release user data for particular type of object */
    if (item->udata) {
        assert(item->obj_class);
        assert(item->obj_class->free_copy_file_udata);
        (item->obj_class->free_copy_file_udata)(item->udata);
    } /* end if */

    /* Release the item */
    item = H5FL_FREE(H5O_addr_map_t, item);

    FUNC_LEAVE_NOAPI(0)
} /* H5O__copy_free_addrmap_cb() */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_header
 *
 * Purpose:     copy header object from one location to another.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_header(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */, hid_t ocpypl_id, hid_t lcpl_id)
{
    H5O_copy_t                   cpy_info;       /* Information for copying object */
    H5P_genplist_t              *ocpy_plist;     /* Object copy property list created */
    H5O_copy_dtype_merge_list_t *dt_list = NULL; /* List of datatype merge suggestions */
    H5O_mcdt_cb_info_t           cb_info;        /* Callback info struct */
    unsigned                     cpy_option = 0; /* Copy options */
    herr_t                       ret_value  = SUCCEED;

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(oloc_src);
    assert(oloc_src->file);
    assert(H5_addr_defined(oloc_src->addr));
    assert(oloc_dst->file);

    /* Initialize copy info before errors can be thrown */
    memset(&cpy_info, 0, sizeof(H5O_copy_t));

    /* Get the copy property list */
    if (NULL == (ocpy_plist = (H5P_genplist_t *)H5I_object(ocpypl_id)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list");

    /* Retrieve the copy parameters */
    if (H5P_get(ocpy_plist, H5O_CPY_OPTION_NAME, &cpy_option) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object copy flag");

    /* Retrieve the merge committed datatype list */
    if (H5P_peek(ocpy_plist, H5O_CPY_MERGE_COMM_DT_LIST_NAME, &dt_list) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get merge committed datatype list");

    /* Get callback info */
    if (H5P_get(ocpy_plist, H5O_CPY_MCDT_SEARCH_CB_NAME, &cb_info) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get callback info");

    /* Convert copy flags into copy struct */
    if ((cpy_option & H5O_COPY_SHALLOW_HIERARCHY_FLAG) > 0) {
        cpy_info.copy_shallow = true;
        cpy_info.max_depth    = 1;
    } /* end if */
    else
        cpy_info.max_depth = -1; /* Current default is for full, recursive hier. copy */
    cpy_info.curr_depth = 0;
    if ((cpy_option & H5O_COPY_EXPAND_SOFT_LINK_FLAG) > 0)
        cpy_info.expand_soft_link = true;
    if ((cpy_option & H5O_COPY_EXPAND_EXT_LINK_FLAG) > 0)
        cpy_info.expand_ext_link = true;
    if ((cpy_option & H5O_COPY_EXPAND_REFERENCE_FLAG) > 0)
        cpy_info.expand_ref = true;
    if ((cpy_option & H5O_COPY_WITHOUT_ATTR_FLAG) > 0)
        cpy_info.copy_without_attr = true;
    if ((cpy_option & H5O_COPY_PRESERVE_NULL_FLAG) > 0)
        cpy_info.preserve_null = true;
    if ((cpy_option & H5O_COPY_MERGE_COMMITTED_DTYPE_FLAG) > 0)
        cpy_info.merge_comm_dt = true;

    /* Add dt_list to copy struct */
    cpy_info.dst_dt_suggestion_list = dt_list;

    /* Add set callback information */
    cpy_info.mcdt_cb = cb_info.func;
    cpy_info.mcdt_ud = cb_info.user_data;

    /* Add property lists needed by callbacks */
    cpy_info.lcpl_id = lcpl_id;

    /* Create a skip list to keep track of which objects are copied */
    if (NULL == (cpy_info.map_list = H5SL_create(H5SL_TYPE_OBJ, NULL)))
        HGOTO_ERROR(H5E_SLIST, H5E_CANTCREATE, FAIL, "cannot make skip list");

    /* copy the object from the source file to the destination file */
    if (H5O__copy_header_real(oloc_src, oloc_dst, &cpy_info, NULL, NULL) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy object");

done:
    if (cpy_info.map_list)
        H5SL_destroy(cpy_info.map_list, H5O__copy_free_addrmap_cb, NULL);
    if (cpy_info.dst_dt_list)
        H5SL_destroy(cpy_info.dst_dt_list, H5O__copy_free_comm_dt_cb, NULL);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_header() */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_obj
 *
 * Purpose:     Copy an object to destination location
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_obj(H5G_loc_t *src_loc, H5G_loc_t *dst_loc, const char *dst_name, hid_t ocpypl_id, hid_t lcpl_id)
{
    H5G_name_t new_path;                 /* Copied object group hier. path */
    H5O_loc_t  new_oloc;                 /* Copied object object location */
    H5G_loc_t  new_loc;                  /* Group location of object copied */
    H5F_t     *cached_dst_file;          /* Cached destination file */
    bool       entry_inserted = false;   /* Flag to indicate that the new entry was inserted into a group */
    herr_t     ret_value      = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    assert(src_loc);
    assert(src_loc->oloc->file);
    assert(dst_loc);
    assert(dst_loc->oloc->file);
    assert(dst_name);

    /* Set up copied object location to fill in */
    new_loc.oloc = &new_oloc;
    new_loc.path = &new_path;
    H5G_loc_reset(&new_loc);
    new_oloc.file = dst_loc->oloc->file;

    /* Make a copy of the destination file, in case the original is changed by
     * H5O__copy_header.  If and when oloc's point to the shared file struct,
     * this will no longer be necessary, so this code can be removed. */
    cached_dst_file = dst_loc->oloc->file;

    /* Copy the object from the source file to the destination file */
    if (H5O__copy_header(src_loc->oloc, &new_oloc, ocpypl_id, lcpl_id) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy object");

    /* Patch dst_loc.  Again, this can be removed once oloc's point to shared
     * file structs. */
    dst_loc->oloc->file = cached_dst_file;

    /* Insert the new object in the destination file's group */
    if (H5L_link(dst_loc, dst_name, &new_loc, lcpl_id) < 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to insert link");
    entry_inserted = true;

done:
    /* Free the ID to name buffers */
    if (entry_inserted)
        H5G_loc_free(&new_loc);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_obj() */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_free_comm_dt_cb
 *
 * Purpose:     Frees the merge committed dt skip list key and object.
 *
 * Return:      SUCCEED (never fails)
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_free_comm_dt_cb(void *item, void *_key, void H5_ATTR_UNUSED *_op_data)
{
    haddr_t                       *addr = (haddr_t *)item;
    H5O_copy_search_comm_dt_key_t *key  = (H5O_copy_search_comm_dt_key_t *)_key;

    FUNC_ENTER_PACKAGE_NOERR

    assert(addr);
    assert(key);
    assert(key->dt);

    key->dt = (H5T_t *)H5O_msg_free(H5O_DTYPE_ID, key->dt);
    key     = H5FL_FREE(H5O_copy_search_comm_dt_key_t, key);
    addr    = H5FL_FREE(haddr_t, addr);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5O__copy_free_comm_dt_cb */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_comm_dt_cmp
 *
 * Purpose:     Skiplist callback used to compare 2 keys for the merge
 *              committed dt list.  Mostly a wrapper for H5T_cmp.
 *
 * Return:      0 if key1 and key2 are equal.
 *              <0 if key1 is less than key2.
 *              >0 if key1 is greater than key2.
 *
 *-------------------------------------------------------------------------
 */
static int
H5O__copy_comm_dt_cmp(const void *_key1, const void *_key2)
{
    const H5O_copy_search_comm_dt_key_t *key1      = (const H5O_copy_search_comm_dt_key_t *)_key1;
    const H5O_copy_search_comm_dt_key_t *key2      = (const H5O_copy_search_comm_dt_key_t *)_key2;
    int                                  ret_value = 0;

    FUNC_ENTER_PACKAGE_NOERR

    /* Check fileno.  It is unlikely to be different so check if they are equal
     * first so only one comparison needs to be made. */
    if (key1->fileno != key2->fileno) {
        if (key1->fileno < key2->fileno)
            HGOTO_DONE(-1);
        if (key1->fileno > key2->fileno)
            HGOTO_DONE(1);
    } /* end if */

    ret_value = H5T_cmp(key1->dt, key2->dt, false);

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_comm_dt_cmp */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_search_comm_dt_attr_cb
 *
 * Purpose:     Callback for H5O_attr_iterate_real from
 *              H5O__copy_search_comm_dt_check.  Checks if the attribute's
 *              datatype is committed.  If it is, adds it to the merge
 *              committed dt skiplist present in udata if it does not match
 *              any already present.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_search_comm_dt_attr_cb(const H5A_t *attr, void *_udata)
{
    H5O_copy_search_comm_dt_ud_t  *udata        = (H5O_copy_search_comm_dt_ud_t *)_udata;
    H5T_t                         *dt           = NULL;    /* Datatype */
    H5O_copy_search_comm_dt_key_t *key          = NULL;    /* Skiplist key */
    haddr_t                       *addr         = NULL;    /* Destination address */
    bool                           obj_inserted = false;   /* Object inserted into skip list */
    herr_t                         ret_value    = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(attr);
    assert(udata);
    assert(udata->dst_dt_list);
    assert(H5_addr_defined(udata->obj_oloc.addr));

    /* Get attribute datatype */
    if (NULL == (dt = H5A_type(attr)))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't get attribute datatype");

    /* Check if the datatype is committed and search the skip list if so */
    if (H5T_is_named(dt)) {
        /* Allocate key */
        if (NULL == (key = H5FL_MALLOC(H5O_copy_search_comm_dt_key_t)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

        /* Copy datatype into key */
        if (NULL == (key->dt = (H5T_t *)H5O_msg_copy(H5O_DTYPE_ID, dt, NULL)))
            HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to copy datatype message");

        /* Get datatype object fileno */
        H5F_GET_FILENO(udata->obj_oloc.file, key->fileno);

        if (!H5SL_search(udata->dst_dt_list, key)) {
            /* Allocate destination address */
            if (NULL == (addr = H5FL_MALLOC(haddr_t)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

            /* Add the destination datatype to the skip list */
            *addr = ((H5O_shared_t *)(key->dt))->u.loc.oh_addr;
            if (H5SL_insert(udata->dst_dt_list, addr, key) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");
            obj_inserted = true;
        } /* end if */
    }     /* end if */

done:
    /* Release resources */
    if (!obj_inserted) {
        if (key) {
            if (key->dt)
                key->dt = (H5T_t *)H5O_msg_free(H5O_DTYPE_ID, key->dt);
            key = H5FL_FREE(H5O_copy_search_comm_dt_key_t, key);
        } /* end if */
        if (addr) {
            assert(ret_value < 0);
            addr = H5FL_FREE(haddr_t, addr);
        } /* end if */
    }     /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_search_comm_dt_attr_cb */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_search_comm_dt_check
 *
 * Purpose:     Check if the object at obj_oloc is or contains a reference
 *              to a committed datatype.  If it does, adds it to the merge
 *              committed dt skiplist present in udata if it does not match
 *              any already present.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_search_comm_dt_check(H5O_loc_t *obj_oloc, H5O_copy_search_comm_dt_ud_t *udata)
{
    H5O_copy_search_comm_dt_key_t *key          = NULL;  /* Skiplist key */
    haddr_t                       *addr         = NULL;  /* Destination address */
    bool                           obj_inserted = false; /* Object inserted into skip list */
    H5A_attr_iter_op_t             attr_op;              /* Attribute iteration operator */
    const H5O_obj_class_t         *obj_class = NULL;     /* Type of object */
    herr_t                         ret_value = SUCCEED;  /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(obj_oloc);
    assert(udata);
    assert(udata->dst_dt_list);
    assert(udata->dst_root_loc);

    /* Get pointer to object class for this object */
    if ((obj_class = H5O__obj_class(obj_oloc)) == NULL)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to determine object type");

    /* Check if the object is a datatype, a dataset using a committed
     * datatype, or contains an attribute using a committed datatype */
    if (obj_class->type == H5O_TYPE_NAMED_DATATYPE) {
        /* Allocate key */
        if (NULL == (key = H5FL_MALLOC(H5O_copy_search_comm_dt_key_t)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

        /* Read the destination datatype */
        if (NULL == (key->dt = (H5T_t *)H5O_msg_read(obj_oloc, H5O_DTYPE_ID, NULL)))
            HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't read DTYPE message");

        /* Get destination object fileno */
        H5F_GET_FILENO(obj_oloc->file, key->fileno);

        /* Check if the datatype is already present in the skip list */
        if (!H5SL_search(udata->dst_dt_list, key)) {
            /* Allocate destination address */
            if (NULL == (addr = H5FL_MALLOC(haddr_t)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

            /* Add the destination datatype to the skip list */
            *addr = obj_oloc->addr;
            if (H5SL_insert(udata->dst_dt_list, addr, key) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");
            obj_inserted = true;
        } /* end if */
    }     /* end if */
    else if (obj_class->type == H5O_TYPE_DATASET) {
        /* Allocate key */
        if (NULL == (key = H5FL_MALLOC(H5O_copy_search_comm_dt_key_t)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

        /* Read the destination datatype */
        if (NULL == (key->dt = (H5T_t *)H5O_msg_read(obj_oloc, H5O_DTYPE_ID, NULL)))
            HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't read DTYPE message");

        /* Check if the datatype is committed and search the skip list if so */
        if (H5T_is_named(key->dt)) {
            /* Get datatype object fileno */
            H5F_GET_FILENO(obj_oloc->file, key->fileno);

            if (!H5SL_search(udata->dst_dt_list, key)) {
                /* Allocate destination address */
                if (NULL == (addr = H5FL_MALLOC(haddr_t)))
                    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

                /* Add the destination datatype to the skip list */
                *addr = ((H5O_shared_t *)(key->dt))->u.loc.oh_addr;
                if (H5SL_insert(udata->dst_dt_list, addr, key) < 0)
                    HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");
                obj_inserted = true;
            } /* end if */
        }     /* end if */
    }         /* end else */

    /* Search within attributes */
    attr_op.op_type      = H5A_ATTR_OP_LIB;
    attr_op.u.lib_op     = H5O__copy_search_comm_dt_attr_cb;
    udata->obj_oloc.file = obj_oloc->file;
    udata->obj_oloc.addr = obj_oloc->addr;
    if (H5O_attr_iterate_real((hid_t)-1, obj_oloc, H5_INDEX_NAME, H5_ITER_NATIVE, (hsize_t)0, NULL, &attr_op,
                              udata) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_BADITER, FAIL, "error iterating over attributes");

done:
    /* Release resources */
    if (!obj_inserted) {
        if (key) {
            if (key->dt)
                key->dt = (H5T_t *)H5O_msg_free(H5O_DTYPE_ID, key->dt);
            key = H5FL_FREE(H5O_copy_search_comm_dt_key_t, key);
        } /* end if */
        if (addr) {
            assert(ret_value < 0);
            addr = H5FL_FREE(haddr_t, addr);
        } /* end if */
    }     /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_search_comm_dt_check */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_search_comm_dt_cb
 *
 * Purpose:     H5G_visit callback to add committed datatypes to the merge
 *              committed dt skiplist.  Mostly a wrapper for
 *              H5O__copy_search_comm_dt_check.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_search_comm_dt_cb(hid_t H5_ATTR_UNUSED group, const char *name, const H5L_info2_t *linfo,
                            void *_udata)
{
    H5O_copy_search_comm_dt_ud_t *udata =
        (H5O_copy_search_comm_dt_ud_t *)_udata; /* Skip list of dtypes in dest file */
    H5G_loc_t  obj_loc;                         /* Location of object */
    H5O_loc_t  obj_oloc;                        /* Object's object location */
    H5G_name_t obj_path;                        /* Object's group hier. path */
    bool       obj_found = false;               /* Object at 'name' found */
    herr_t     ret_value = H5_ITER_CONT;        /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(name);
    assert(linfo);
    assert(udata);
    assert(udata->dst_dt_list);
    assert(udata->dst_root_loc);

    /* Check if this is a hard link */
    if (linfo->type == H5L_TYPE_HARD) {
        /* Set up opened group location to fill in */
        obj_loc.oloc = &obj_oloc;
        obj_loc.path = &obj_path;
        H5G_loc_reset(&obj_loc);

        /* Find the object */
        if (H5G_loc_find(udata->dst_root_loc, name, &obj_loc /*out*/) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_NOTFOUND, H5_ITER_ERROR, "object not found");
        obj_found = true;

        /* Check object and add to skip list if appropriate */
        if (H5O__copy_search_comm_dt_check(&obj_oloc, udata) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, H5_ITER_ERROR, "can't check object");
    } /* end if */

done:
    /* Release resources */
    if (obj_found && H5G_loc_free(&obj_loc) < 0)
        HDONE_ERROR(H5E_OHDR, H5E_CANTRELEASE, H5_ITER_ERROR, "can't free location");

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_search_comm_dt_cb */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_search_comm_dt
 *
 * Purpose:     Checks if the committed datatype present in oh_src matches any
 *              in the destination file, building the destination file
 *              skiplist as necessary.
 *
 * Return:      true if a match is found in the destination file
 *                      - oloc_dst will contain the address
 *              false if a match is not found
 *              Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static htri_t
H5O__copy_search_comm_dt(H5F_t *file_src, H5O_t *oh_src, H5O_loc_t *oloc_dst /*in, out*/,
                         H5O_copy_t *cpy_info)
{
    H5O_copy_search_comm_dt_key_t *key = NULL;                  /* Skiplist key */
    haddr_t                       *dst_addr;                    /* Destination datatype address */
    H5G_loc_t                      dst_root_loc = {NULL, NULL}; /* Destination root group location */
    H5O_copy_search_comm_dt_ud_t   udata;                       /* Group iteration user data */
    herr_t                         ret_value = false;           /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(oh_src);
    assert(oloc_dst);
    assert(oloc_dst->file);
    assert(H5F_ID_EXISTS(oloc_dst->file));
    assert(cpy_info);

    /* Allocate key */
    if (NULL == (key = H5FL_MALLOC(H5O_copy_search_comm_dt_key_t)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Read the source datatype */
    if (NULL == (key->dt = (H5T_t *)H5O_msg_read_oh(file_src, oh_src, H5O_DTYPE_ID, NULL)))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't read DTYPE message");

    /* Get destination object fileno */
    H5F_GET_FILENO(oloc_dst->file, key->fileno);

    /* Check if the destination dtype list exists, create it if it does not */
    if (!cpy_info->dst_dt_list) {
        /* Create the skip list */
        if (NULL == (cpy_info->dst_dt_list = H5SL_create(H5SL_TYPE_GENERIC, H5O__copy_comm_dt_cmp)))
            HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "can't create skip list for committed datatypes");

        /* Add suggested types to list, if they are present */
        if (cpy_info->dst_dt_suggestion_list) {
            H5O_copy_dtype_merge_list_t *suggestion = cpy_info->dst_dt_suggestion_list;
            H5G_loc_t                    obj_loc;  /* Location of object */
            H5O_loc_t                    obj_oloc; /* Object's object location */
            H5G_name_t                   obj_path; /* Object's group hier. path */

            /* Set up the root group in the destination file */
            if (NULL == (dst_root_loc.oloc = H5G_oloc(H5G_rootof(oloc_dst->file))))
                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to get object location for root group");
            if (NULL == (dst_root_loc.path = H5G_nameof(H5G_rootof(oloc_dst->file))))
                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to get path for root group");

            /* Set up opened group location to fill in */
            obj_loc.oloc = &obj_oloc;
            obj_loc.path = &obj_path;
            H5G_loc_reset(&obj_loc);

            /* Build udata */
            udata.dst_dt_list   = cpy_info->dst_dt_list;
            udata.dst_root_loc  = &dst_root_loc;
            udata.obj_oloc.file = NULL;
            udata.obj_oloc.addr = HADDR_UNDEF;

            /* Walk through the list of datatype suggestions */
            while (suggestion) {
                /* Find the object */
                if (H5G_loc_find(&dst_root_loc, suggestion->path, &obj_loc /*out*/) < 0)
                    /* Ignore errors - i.e. suggestions not present in
                     * destination file */
                    H5E_clear_stack(NULL);
                else
                    /* Check object and add to skip list if appropriate */
                    if (H5O__copy_search_comm_dt_check(&obj_oloc, &udata) < 0) {
                        if (H5G_loc_free(&obj_loc) < 0)
                            HERROR(H5E_OHDR, H5E_CANTRELEASE, "can't free location");
                        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't check object");
                    } /* end if */

                /* Free location */
                if (H5G_loc_free(&obj_loc) < 0)
                    HGOTO_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "can't free location");

                /* Advance the suggestion pointer */
                suggestion = suggestion->next;
            } /* end while */
        }     /* end if */
    }

    if (!cpy_info->dst_dt_list_complete) {
        /* Search for the type in the destination file, and return its address
         * if found, but only if the list is populated with and only with
         * suggested types.  We will search complete lists later. */
        if (cpy_info->dst_dt_suggestion_list &&
            NULL != (dst_addr = (haddr_t *)H5SL_search(cpy_info->dst_dt_list, key))) {
            oloc_dst->addr = *dst_addr;
            ret_value      = true;
        } /* end if */
        else {
            H5O_mcdt_search_ret_t search_cb_ret = H5O_MCDT_SEARCH_CONT;

            /* Make callback to see if we should search destination file */
            if (cpy_info->mcdt_cb)
                if ((search_cb_ret = cpy_info->mcdt_cb(cpy_info->mcdt_ud)) == H5O_MCDT_SEARCH_ERROR)
                    HGOTO_ERROR(H5E_OHDR, H5E_CALLBACK, FAIL, "callback returned error");

            if (search_cb_ret == H5O_MCDT_SEARCH_CONT) {
                /* Build the complete dst dt list */
                /* Set up the root group in the destination file, if necessary */
                if (!dst_root_loc.oloc) {
                    assert(!dst_root_loc.path);
                    if (NULL == (dst_root_loc.oloc = H5G_oloc(H5G_rootof(oloc_dst->file))))
                        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL,
                                    "unable to get object location for root group");
                    if (NULL == (dst_root_loc.path = H5G_nameof(H5G_rootof(oloc_dst->file))))
                        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to get path for root group");
                } /* end if */
                else
                    assert(dst_root_loc.path);

                /* Build udata.  Note that this may be done twice in some cases, but
                 * it should be rare and should be cheaper on average than trying to
                 * keep track of whether it was done before. */
                udata.dst_dt_list   = cpy_info->dst_dt_list;
                udata.dst_root_loc  = &dst_root_loc;
                udata.obj_oloc.file = NULL;
                udata.obj_oloc.addr = HADDR_UNDEF;

                /* Traverse the destination file, adding committed datatypes to the skip
                 * list */
                if (H5G_visit(&dst_root_loc, "/", H5_INDEX_NAME, H5_ITER_NATIVE, H5O__copy_search_comm_dt_cb,
                              &udata) < 0)
                    HGOTO_ERROR(H5E_OHDR, H5E_BADITER, FAIL, "object visitation failed");
                cpy_info->dst_dt_list_complete = true;
            } /* end if */
            else if (search_cb_ret != H5O_MCDT_SEARCH_STOP)
                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unknown return value for callback");
        } /* end if */
    }     /* end if */

    /* Search for the type in the destination file, and return its address if
     * found, but only if the list is complete */
    if (cpy_info->dst_dt_list_complete) {
        if (NULL != (dst_addr = (haddr_t *)H5SL_search(cpy_info->dst_dt_list, key))) {
            oloc_dst->addr = *dst_addr;
            ret_value      = true;
        } /* end if */
    }     /* end if */

done:
    if (key) {
        if (key->dt)
            key->dt = (H5T_t *)H5O_msg_free(H5O_DTYPE_ID, key->dt);
        key = H5FL_FREE(H5O_copy_search_comm_dt_key_t, key);
    } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_search_comm_dt */

/*-------------------------------------------------------------------------
 * Function:    H5O__copy_insert_comm_dt
 *
 * Purpose:     Insert the committed datatype at oloc_dst into the merge committed
 *              dt skiplist.  The datatype must not be present already.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__copy_insert_comm_dt(H5F_t *file_src, H5O_t *oh_src, H5O_loc_t *oloc_dst, H5O_copy_t *cpy_info)
{
    H5O_copy_search_comm_dt_key_t *key       = NULL;    /* Skiplist key */
    haddr_t                       *addr      = NULL;    /* Destination object address */
    herr_t                         ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(oh_src);
    assert(oloc_dst);
    assert(oloc_dst->file);
    assert(oloc_dst->addr != HADDR_UNDEF);
    assert(cpy_info);
    assert(cpy_info->dst_dt_list);

    /* Allocate key */
    if (NULL == (key = H5FL_MALLOC(H5O_copy_search_comm_dt_key_t)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Read the datatype.  Read from the source file because the destination
     * object could be changed in the post-copy. */
    if (NULL == (key->dt = (H5T_t *)H5O_msg_read_oh(file_src, oh_src, H5O_DTYPE_ID, NULL)))
        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't read DTYPE message");

    /* Get destination object fileno */
    H5F_GET_FILENO(oloc_dst->file, key->fileno);

    /* Allocate destination address */
    if (NULL == (addr = H5FL_MALLOC(haddr_t)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");

    /* Add the destination datatype to the skip list */
    *addr = oloc_dst->addr;
    if (H5SL_insert(cpy_info->dst_dt_list, addr, key) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "can't insert object into skip list");

done:
    if (ret_value < 0) {
        if (key) {
            if (key->dt)
                key->dt = (H5T_t *)H5O_msg_free(H5O_DTYPE_ID, key->dt);
            key = H5FL_FREE(H5O_copy_search_comm_dt_key_t, key);
        } /* end if */
        if (addr)
            addr = H5FL_FREE(haddr_t, addr);
    } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__copy_insert_comm_dt */