path: root/src/H5Olink.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.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*-------------------------------------------------------------------------
 *
 * Created:             H5Olink.c
 *                      Aug 29 2005
 *                      Quincey Koziol <koziol@ncsa.uiuc.edu>
 *
 * Purpose:             Link messages.
 *
 *-------------------------------------------------------------------------
 */

#define H5G_FRIEND		/*suppress error about including H5Gpkg   */
#define H5L_FRIEND		/*suppress error about including H5Lpkg	  */
#include "H5Omodule.h"          /* This source code file is part of the H5O module */


#include "H5private.h"		/* Generic Functions			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5FLprivate.h"	/* Free lists                           */
#include "H5Gpkg.h"		/* Groups		  		*/
#include "H5Iprivate.h"         /* IDs                                  */
#include "H5Lpkg.h"             /* Links                                */
#include "H5MMprivate.h"	/* Memory management			*/
#include "H5Opkg.h"             /* Object headers			*/


/* PRIVATE PROTOTYPES */
static void *H5O__link_decode(H5F_t *f, H5O_t *open_oh, unsigned mesg_flags,
    unsigned *ioflags, size_t p_size, const uint8_t *p);
static herr_t H5O_link_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
static void *H5O_link_copy(const void *_mesg, void *_dest);
static size_t H5O_link_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
static herr_t H5O__link_reset(void *_mesg);
static herr_t H5O__link_free(void *_mesg);
static herr_t H5O_link_pre_copy_file(H5F_t *file_src, const void *mesg_src,
    hbool_t *deleted, const H5O_copy_t *cpy_info, void *udata);
static void *H5O__link_copy_file(H5F_t *file_src, void *native_src,
    H5F_t *file_dst, hbool_t *recompute_size, unsigned *mesg_flags,
    H5O_copy_t *cpy_info, void *udata);
static herr_t H5O__link_post_copy_file(const H5O_loc_t *src_oloc,
    const void *mesg_src, H5O_loc_t *dst_oloc, void *mesg_dst,
    unsigned *mesg_flags, H5O_copy_t *cpy_info);
static herr_t H5O__link_debug(H5F_t *f, const void *_mesg, FILE *stream,
    int indent, int fwidth);

/* This message derives from H5O message class */
const H5O_msg_class_t H5O_MSG_LINK[1] = {{
    H5O_LINK_ID,            	/*message id number             */
    "link",                 	/*message name for debugging    */
    sizeof(H5O_link_t),     	/*native message size           */
    0,				/* messages are sharable?       */
    H5O__link_decode,        	/*decode message                */
    H5O_link_encode,        	/*encode message                */
    H5O_link_copy,          	/*copy the native value         */
    H5O_link_size,          	/*size of symbol table entry    */
    H5O__link_reset,		/* reset method			*/
    H5O__link_free,	        /* free method			*/
    H5O_link_delete,	       	/* file delete method		*/
    NULL,			/* link method			*/
    NULL, 			/*set share method		*/
    NULL,		    	/*can share method		*/
    H5O_link_pre_copy_file,	/* pre copy native value to file */
    H5O__link_copy_file,	/* copy native value to file    */
    H5O__link_post_copy_file,	/* post copy native value to file    */
    NULL,			/* get creation index		*/
    NULL,			/* set creation index		*/
    H5O__link_debug          	/*debug the message             */
}};

/* Current version of link information */
#define H5O_LINK_VERSION 	1

/* Flags for link flag encoding */
#define H5O_LINK_NAME_SIZE              0x03    /* 2-bit field for size of name length */
#define H5O_LINK_STORE_CORDER           0x04    /* Whether to store creation index */
#define H5O_LINK_STORE_LINK_TYPE        0x08    /* Whether to store non-default link type */
#define H5O_LINK_STORE_NAME_CSET        0x10    /* Whether to store non-default name character set */
#define H5O_LINK_ALL_FLAGS              (H5O_LINK_NAME_SIZE | H5O_LINK_STORE_CORDER | H5O_LINK_STORE_LINK_TYPE | H5O_LINK_STORE_NAME_CSET)

/* Individual definitions of name size values */
#define H5O_LINK_NAME_1                 0x00    /* Use 1-byte value for name length */
#define H5O_LINK_NAME_2                 0x01    /* Use 2-byte value for name length */
#define H5O_LINK_NAME_4                 0x02    /* Use 4-byte value for name length */
#define H5O_LINK_NAME_8                 0x03    /* Use 8-byte value for name length */

/* Declare a free list to manage the H5O_link_t struct */
H5FL_DEFINE_STATIC(H5O_link_t);


/*-------------------------------------------------------------------------
 * Function:    H5O__link_decode
 *
 * Purpose:     Decode a message and return a pointer to
 *              a newly allocated one.
 *
 * Return:      Success:        Ptr to new message in native order.
 *
 *              Failure:        NULL
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Aug 29 2005
 *
 *-------------------------------------------------------------------------
 */
static void *
H5O__link_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh,
    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
{
    H5O_link_t          *lnk = NULL;    /* Pointer to link message */
    size_t              len = 0;        /* Length of a string in the message */
    unsigned char       link_flags;     /* Flags for encoding link info */
    void                *ret_value = NULL;      /* Return value */

    FUNC_ENTER_STATIC

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

    /* decode */
    if(*p++ != H5O_LINK_VERSION)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad version number for message")

    /* Allocate space for message */
    if(NULL == (lnk = H5FL_CALLOC(H5O_link_t)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* Get the encoding flags for the link */
    link_flags = *p++;
    if(link_flags & ~H5O_LINK_ALL_FLAGS)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad flag value for message")

    /* Check for non-default link type */
    if(link_flags & H5O_LINK_STORE_LINK_TYPE) {
        /* Get the type of the link */
        lnk->type = (H5L_type_t)*p++;
        if(lnk->type < H5L_TYPE_HARD || lnk->type > H5L_TYPE_MAX)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad link type")
    } /* end if */
    else
        lnk->type = H5L_TYPE_HARD;

    /* Get the link creation time from the file */
    if(link_flags & H5O_LINK_STORE_CORDER) {
        INT64DECODE(p, lnk->corder)
        lnk->corder_valid = TRUE;
    } /* end if */
    else {
        lnk->corder = 0;
        lnk->corder_valid = FALSE;
    } /* end else */

    /* Check for non-default name character set */
    if(link_flags & H5O_LINK_STORE_NAME_CSET) {
        /* Get the link name's character set */
        lnk->cset = (H5T_cset_t)*p++;
        if(lnk->cset < H5T_CSET_ASCII || lnk->cset > H5T_CSET_UTF8)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad cset type")
    } /* end if */
    else
        lnk->cset = H5T_CSET_ASCII;

    /* Get the length of the link's name */
    switch(link_flags & H5O_LINK_NAME_SIZE) {
        case 0:     /* 1 byte size */
            len = *p++;
            break;

        case 1:     /* 2 byte size */
            UINT16DECODE(p, len);
            break;

        case 2:     /* 4 byte size */
            UINT32DECODE(p, len);
            break;

        case 3:     /* 8 byte size */
            UINT64DECODE(p, len);
            break;

        default:
            HDassert(0 && "bad size for name");
    } /* end switch */
    if(len == 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "invalid name length")

    /* Get the link's name */
    if(NULL == (lnk->name = (char *)H5MM_malloc(len + 1)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
    HDmemcpy(lnk->name, p, len);
    lnk->name[len] = '\0';
    p += len;

    /* Get the appropriate information for each type of link */
    switch(lnk->type) {
        case H5L_TYPE_HARD:
            /* Get the address of the object the link points to */
            H5F_addr_decode(f, &p, &(lnk->u.hard.addr));
            break;

        case H5L_TYPE_SOFT:
            /* Get the link value */
            UINT16DECODE(p, len)
            if(len == 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "invalid link length")
            if(NULL == (lnk->u.soft.name = (char *)H5MM_malloc((size_t)len + 1)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
            HDmemcpy(lnk->u.soft.name, p, len);
            lnk->u.soft.name[len] = '\0';
            p += len;
            break;

        /* User-defined links */
        case H5L_TYPE_EXTERNAL:
        case H5L_TYPE_ERROR:
        case H5L_TYPE_MAX:
        default:
            if(lnk->type < H5L_TYPE_UD_MIN || lnk->type > H5L_TYPE_MAX)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "unknown link type")

            /* A UD link.  Get the user-supplied data */
            UINT16DECODE(p, len)
            lnk->u.ud.size = len;
            if(len > 0)
            {
                if(NULL == (lnk->u.ud.udata = H5MM_malloc((size_t)len)))
                    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
                HDmemcpy(lnk->u.ud.udata, p, len);
                p += len;
            }
            else
                lnk->u.ud.udata = NULL;
    } /* end switch */

    /* Set return value */
    ret_value = lnk;

done:
    if(ret_value == NULL)
        if(lnk != NULL) {
            if(lnk->name != NULL)
                H5MM_xfree(lnk->name);
            if(lnk->type == H5L_TYPE_SOFT && lnk->u.soft.name != NULL)
                H5MM_xfree(lnk->u.soft.name);
            if(lnk->type >= H5L_TYPE_UD_MIN && lnk->u.ud.size > 0 && lnk->u.ud.udata != NULL)
                H5MM_xfree(lnk->u.ud.udata);
            lnk = H5FL_FREE(H5O_link_t, lnk);
        } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__link_decode() */


/*-------------------------------------------------------------------------
 * Function:    H5O_link_encode
 *
 * Purpose:     Encodes a link message.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Aug 29 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O_link_encode(H5F_t *f, hbool_t H5_ATTR_UNUSED disable_shared, uint8_t *p, const void *_mesg)
{
    const H5O_link_t    *lnk = (const H5O_link_t *) _mesg;
    uint64_t            len;            /* Length of a string in the message */
    unsigned char       link_flags;     /* Flags for encoding link info */

    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /* check args */
    HDassert(f);
    HDassert(p);
    HDassert(lnk);

    /* Get length of link's name */
    len = (uint64_t)HDstrlen(lnk->name);
    HDassert(len > 0);

    /* encode */
    *p++ = H5O_LINK_VERSION;

    /* The encoding flags for the link */
    if(len > 4294967295)
        link_flags = H5O_LINK_NAME_8;
    else if(len > 65535)
        link_flags = H5O_LINK_NAME_4;
    else if(len > 255)
        link_flags = H5O_LINK_NAME_2;
    else
        link_flags = H5O_LINK_NAME_1;
    link_flags = (unsigned char)(link_flags | (lnk->corder_valid ? H5O_LINK_STORE_CORDER : 0));
    link_flags = (unsigned char)(link_flags | ((lnk->type != H5L_TYPE_HARD) ? H5O_LINK_STORE_LINK_TYPE : 0));
    link_flags = (unsigned char)(link_flags | ((lnk->cset != H5T_CSET_ASCII) ? H5O_LINK_STORE_NAME_CSET : 0));
    *p++ = link_flags;

    /* Store the type of a non-default link */
    if(link_flags & H5O_LINK_STORE_LINK_TYPE)
        *p++ = (uint8_t)lnk->type;

    /* Store the link creation order in the file, if its valid */
    if(lnk->corder_valid)
        INT64ENCODE(p, lnk->corder)

    /* Store a non-default link name character set */
    if(link_flags & H5O_LINK_STORE_NAME_CSET)
        *p++ = (uint8_t)lnk->cset;

    /* Store the link name's length */
    switch(link_flags & H5O_LINK_NAME_SIZE) {
        case 0:     /* 1 byte size */
            *p++ = (uint8_t)len;
            break;

        case 1:     /* 2 byte size */
            UINT16ENCODE(p, len);
            break;

        case 2:     /* 4 byte size */
            UINT32ENCODE(p, len);
            break;

        case 3:     /* 8 byte size */
            UINT64ENCODE(p, len);
            break;

        default:
            HDassert(0 && "bad size for name");
    } /* end switch */

    /* Store the link's name */
    HDmemcpy(p, lnk->name, (size_t)len);
    p += len;

    /* Store the appropriate information for each type of link */
    switch(lnk->type) {
        case H5L_TYPE_HARD:
            /* Store the address of the object the link points to */
            H5F_addr_encode(f, &p, lnk->u.hard.addr);
            break;

        case H5L_TYPE_SOFT:
            /* Store the link value */
            len = (uint16_t)HDstrlen(lnk->u.soft.name);
            HDassert(len > 0);
            UINT16ENCODE(p, len)
            HDmemcpy(p, lnk->u.soft.name, (size_t)len);
            p += len;
            break;

        /* User-defined links */
        case H5L_TYPE_EXTERNAL:
        case H5L_TYPE_ERROR:
        case H5L_TYPE_MAX:
        default:
            HDassert(lnk->type >= H5L_TYPE_UD_MIN && lnk->type <= H5L_TYPE_MAX);

            /* Store the user-supplied data, however long it is */
            len = (uint16_t)lnk->u.ud.size;
            UINT16ENCODE(p, len)
            if(len > 0)
            {
                HDmemcpy(p, lnk->u.ud.udata, (size_t)len);
                p+=len;
            }
            break;
    } /* end switch */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5O_link_encode() */


/*-------------------------------------------------------------------------
 * Function:    H5O_link_copy
 *
 * Purpose:     Copies a message from _MESG to _DEST, allocating _DEST if
 *              necessary.
 *
 * Return:      Success:        Ptr to _DEST
 *
 *              Failure:        NULL
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Aug 29 2005
 *
 *-------------------------------------------------------------------------
 */
static void *
H5O_link_copy(const void *_mesg, void *_dest)
{
    const H5O_link_t    *lnk = (const H5O_link_t *) _mesg;
    H5O_link_t          *dest = (H5O_link_t *) _dest;
    void                *ret_value = NULL;      /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Check args */
    HDassert(lnk);
    if(!dest && NULL == (dest = H5FL_MALLOC(H5O_link_t)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* Copy static information */
    *dest = *lnk;

    /* Duplicate the link's name */
    HDassert(lnk->name);
    if(NULL == (dest->name = H5MM_xstrdup(lnk->name)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't duplicate link name")

    /* Copy other information needed for different link types */
    if(lnk->type == H5L_TYPE_SOFT) {
        if(NULL == (dest->u.soft.name = H5MM_xstrdup(lnk->u.soft.name)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't duplicate soft link value")
    } /* end if */
    else if(lnk->type >= H5L_TYPE_UD_MIN) {
        if(lnk->u.ud.size > 0) {
            if(NULL == (dest->u.ud.udata = H5MM_malloc(lnk->u.ud.size)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
            HDmemcpy(dest->u.ud.udata, lnk->u.ud.udata, lnk->u.ud.size);
        } /* end if */
    } /* end if */

    /* Set return value */
    ret_value = dest;

done:
    if(NULL == ret_value)
        if(dest) {
            if(dest->name && dest->name != lnk->name)
                dest->name = (char *)H5MM_xfree(dest->name);
            if(NULL == _dest)
                dest = H5FL_FREE(H5O_link_t ,dest);
        } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O_link_copy() */


/*-------------------------------------------------------------------------
 * Function:    H5O_link_size
 *
 * Purpose:     Returns the size of the raw message in bytes not counting
 *              the message type or size fields, but only the data fields.
 *              This function doesn't take into account alignment.
 *
 * Return:      Success:        Message data size in bytes without alignment.
 *
 *              Failure:        zero
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Aug 29 2005
 *
 *-------------------------------------------------------------------------
 */
static size_t
H5O_link_size(const H5F_t *f, hbool_t H5_ATTR_UNUSED disable_shared, const void *_mesg)
{
    const H5O_link_t *lnk = (const H5O_link_t *)_mesg;
    uint64_t name_len;          /* Length of name */
    size_t name_size;           /* Size of encoded name length */
    size_t ret_value = 0;       /* Return value */

    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /* Sanity check */
    HDcompile_assert(sizeof(uint64_t) >= sizeof(size_t));

    /* Get name's length */
    name_len = (uint64_t)HDstrlen(lnk->name);

    /* Determine correct value for name size bits */
    if(name_len > 4294967295)
        name_size = 8;
    else if(name_len > 65535)
        name_size = 4;
    else if(name_len > 255)
        name_size = 2;
    else
        name_size = 1;

    /* Set return value */
    ret_value = 1 +                     /* Version */
                1 +                     /* Link encoding flags */
                (lnk->type != H5L_TYPE_HARD ? (size_t)1 : 0) + /* Link type */
                (lnk->corder_valid ? 8 : 0) + /* Creation order */
                (lnk->cset != H5T_CSET_ASCII ? 1 : 0) + /* Character set */
                name_size +             /* Name length */
                name_len;               /* Name */

    /* Add the appropriate length for each type of link */
    switch(lnk->type) {
        case H5L_TYPE_HARD:
            ret_value += H5F_SIZEOF_ADDR(f);
            break;

        case H5L_TYPE_SOFT:
            ret_value += 2 +                            /* Link value length */
                        HDstrlen(lnk->u.soft.name);     /* Link value */
            break;

        case H5L_TYPE_ERROR:
        case H5L_TYPE_EXTERNAL:
        case H5L_TYPE_MAX:
        default: /* Default is user-defined link type */
            HDassert(lnk->type >= H5L_TYPE_UD_MIN);
            ret_value += 2 +                            /* User-defined data size */
                         lnk->u.ud.size;                /* User-defined data */
            break;
    } /* end switch */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O_link_size() */


/*-------------------------------------------------------------------------
 * Function:	H5O__link_reset
 *
 * Purpose:	Frees resources within a message, but doesn't free
 *		the message itself.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Monday, August 29, 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__link_reset(void *_mesg)
{
    H5O_link_t *lnk = (H5O_link_t *)_mesg;

    FUNC_ENTER_STATIC_NOERR

    if(lnk) {
        /* Free information for link (but don't free link pointer) */
        if(lnk->type == H5L_TYPE_SOFT)
            lnk->u.soft.name = (char *)H5MM_xfree(lnk->u.soft.name);
        else if (lnk->type >= H5L_TYPE_UD_MIN) {
            if(lnk->u.ud.size > 0)
                lnk->u.ud.udata = H5MM_xfree(lnk->u.ud.udata);
        } /* end if */
        lnk->name = (char *)H5MM_xfree(lnk->name);
    } /* end if */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5O__link_reset() */


/*-------------------------------------------------------------------------
 * Function:	H5O__link_free
 *
 * Purpose:	Frees the message contents and the message itself
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Monday, August 29, 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__link_free(void *_mesg)
{
    H5O_link_t *lnk = (H5O_link_t *)_mesg;

    FUNC_ENTER_STATIC_NOERR

    HDassert(lnk);

    lnk = H5FL_FREE(H5O_link_t, lnk);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5O__link_free() */


/*-------------------------------------------------------------------------
 * Function:    H5O_link_delete
 *
 * Purpose:     Free file space referenced by message
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  Quincey Koziol
 *              Monday, August 29, 2005
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5O_link_delete(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, void *_mesg)
{
    H5O_link_t *lnk = (H5O_link_t *)_mesg;
    herr_t ret_value = SUCCEED;   /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

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

    /* Check for adjusting the link count when the link is removed */
    /* Adjust the reference count of the object when a hard link is removed */
    if(lnk->type == H5L_TYPE_HARD) {
        H5O_loc_t oloc;

        /* Construct object location for object, in order to decrement it's ref count */
        H5O_loc_reset(&oloc);
        oloc.file = f;
        HDassert(H5F_addr_defined(lnk->u.hard.addr));
        oloc.addr = lnk->u.hard.addr;

        /* Decrement the ref count for the object */
        if(H5O_link(&oloc, -1) < 0)
            HGOTO_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to decrement object link count")
    } /* end if */
    /* Perform the "delete" callback when a user-defined link is removed */
    else if(lnk->type >= H5L_TYPE_UD_MIN) {
        const H5L_class_t   *link_class;         /* User-defined link class */

        /* Get the link class for this type of link. */
        if(NULL == (link_class = H5L_find_class(lnk->type)))
            HGOTO_ERROR(H5E_OHDR, H5E_NOTREGISTERED, FAIL, "link class not registered")

        /* Check for delete callback */
        if(link_class->del_func) {
            hid_t file_id;           /* ID for the file the link is located in (passed to user callback) */

            /* Get a file ID for the file the link is in */
            if((file_id = H5F_get_id(f, FALSE)) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "unable to get file ID")

            /* Call user-defined link's 'delete' callback */
            if((link_class->del_func)(lnk->name, file_id, lnk->u.ud.udata, lnk->u.ud.size) < 0) {
                H5I_dec_ref(file_id);
                HGOTO_ERROR(H5E_OHDR, H5E_CALLBACK, FAIL, "link deletion callback returned failure")
            } /* end if */

            /* Release the file ID */
            if(H5I_dec_ref(file_id) < 0)
                HGOTO_ERROR(H5E_OHDR, H5E_CANTCLOSEFILE, FAIL, "can't close file")
        } /* end if */
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O_link_delete() */


/*-------------------------------------------------------------------------
 * Function:    H5O_link_pre_copy_file
 *
 * Purpose:     Perform any necessary actions before copying message between
 *              files for link messages.
 *
 * Return:      Success:        Non-negative
 *
 *              Failure:        Negative
 *
 * Programmer:  Quincey Koziol
 *              Monday, June 26, 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O_link_pre_copy_file(H5F_t H5_ATTR_UNUSED *file_src, const void H5_ATTR_UNUSED *native_src,
    hbool_t *deleted, const H5O_copy_t *cpy_info, void H5_ATTR_UNUSED *udata)
{
    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /* check args */
    HDassert(deleted);
    HDassert(cpy_info);

    /* If we are performing a 'shallow hierarchy' copy, and this link won't
     *  be included in the final group, indicate that it should be deleted
     *  in the destination object header before performing any other actions
     *  on it.
     */
    if(cpy_info->max_depth >= 0 && cpy_info->curr_depth >= cpy_info->max_depth)
        *deleted = TRUE;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5O_link_pre_copy_file() */


/*-------------------------------------------------------------------------
 * Function:    H5O__link_copy_file
 *
 * Purpose:     Copies a message from _MESG to _DEST in file
 *
 * Return:      Success:        Ptr to _DEST
 *
 *              Failure:        NULL
 *
 * Programmer:  Quincey Koziol
 *              November  7, 2005
 *
 *-------------------------------------------------------------------------
 */
static void *
H5O__link_copy_file(H5F_t H5_ATTR_UNUSED *file_src, void *native_src, H5F_t H5_ATTR_UNUSED *file_dst,
    hbool_t H5_ATTR_UNUSED *recompute_size, unsigned H5_ATTR_UNUSED *mesg_flags,
    H5O_copy_t H5_ATTR_UNUSED *cpy_info, void H5_ATTR_UNUSED *udata)
{
    H5O_link_t  *link_src = (H5O_link_t *)native_src;
    void *ret_value = NULL;     /* Return value */

    FUNC_ENTER_STATIC

    /* check args */
    HDassert(link_src);
    HDassert(cpy_info);
    HDassert(cpy_info->max_depth < 0 || cpy_info->curr_depth < cpy_info->max_depth);

    /* Sanity check source link type */
    if(link_src->type > H5L_TYPE_SOFT && link_src->type < H5L_TYPE_UD_MIN)
        HGOTO_ERROR(H5E_SYM, H5E_BADVALUE, NULL, "unrecognized built-in link type")

    /* Allocate "blank" link for destination */
    /* (values will be filled in during 'post copy' operation) */
    if(NULL == (ret_value = H5FL_CALLOC(H5O_link_t)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5O__link_copy_file() */


/*-------------------------------------------------------------------------
 * Function:    H5O__link_post_copy_file
 *
 * Purpose:     Finish copying a message from between files
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  Quincey Koziol
 *              November  7, 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__link_post_copy_file(const H5O_loc_t *src_oloc, const void *mesg_src,
    H5O_loc_t *dst_oloc, void *mesg_dst, unsigned H5_ATTR_UNUSED *mesg_flags,
    H5O_copy_t *cpy_info)
{
    const H5O_link_t    *link_src = (const H5O_link_t *)mesg_src;
    H5O_link_t          *link_dst = (H5O_link_t *)mesg_dst;
    herr_t              ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_STATIC

    /* check args */
    HDassert(link_src);
    HDassert(dst_oloc);
    HDassert(H5F_addr_defined(dst_oloc->addr));
    HDassert(dst_oloc->file);
    HDassert(link_dst);
    HDassert(cpy_info);
    HDassert(cpy_info->max_depth < 0 || cpy_info->curr_depth < cpy_info->max_depth);

    /* Copy the link (and the object it points to) */
    if(H5L__link_copy_file(dst_oloc->file, link_src, src_oloc, link_dst, cpy_info) < 0)
        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to copy link")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* H5O__link_post_copy_file() */


/*-------------------------------------------------------------------------
 * Function:    H5O__link_debug
 *
 * Purpose:     Prints debugging info for a message.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  Quincey Koziol
 *              koziol@ncsa.uiuc.edu
 *              Aug 29 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5O__link_debug(H5F_t H5_ATTR_UNUSED *f, const void *_mesg, FILE *stream,
    int indent, int fwidth)
{
    const H5O_link_t    *lnk = (const H5O_link_t *) _mesg;
    herr_t               ret_value = SUCCEED;          /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* check args */
    HDassert(f);
    HDassert(lnk);
    HDassert(stream);
    HDassert(indent >= 0);
    HDassert(fwidth >= 0);

    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
	      "Link Type:", (lnk->type == H5L_TYPE_HARD ? "Hard" :
                  (lnk->type == H5L_TYPE_SOFT ? "Soft" :
                  (lnk->type == H5L_TYPE_EXTERNAL ? "External" :
                  (lnk->type >= H5L_TYPE_UD_MIN ? "User-defined" : "Unknown")))));

    if(lnk->corder_valid)
        HDfprintf(stream, "%*s%-*s %a\n", indent, "", fwidth,
                  "Creation Order:", lnk->corder);

    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
	      "Link Name Character Set:", (lnk->cset == H5T_CSET_ASCII ?
                "ASCII" : (lnk->cset == H5T_CSET_UTF8 ? "UTF-8" : "Unknown")));
    HDfprintf(stream, "%*s%-*s '%s'\n", indent, "", fwidth,
	      "Link Name:", lnk->name);

    /* Display link-specific information */
    switch(lnk->type) {
        case H5L_TYPE_HARD:
            HDfprintf(stream, "%*s%-*s %a\n", indent, "", fwidth,
                      "Object address:", lnk->u.hard.addr);
            break;

        case H5L_TYPE_SOFT:
            HDfprintf(stream, "%*s%-*s '%s'\n", indent, "", fwidth,
                      "Link Value:", lnk->u.soft.name);
            break;

        case H5L_TYPE_ERROR:
        case H5L_TYPE_EXTERNAL:
        case H5L_TYPE_MAX:
        default:
            if(lnk->type >= H5L_TYPE_UD_MIN) {
                if(lnk->type == H5L_TYPE_EXTERNAL) {
                    const char *objname = (const char *)lnk->u.ud.udata + (HDstrlen((const char *)lnk->u.ud.udata) + 1);

                    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
                              "External File Name:", lnk->u.ud.udata);
                    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
                              "External Object Name:", objname);
                } /* end if */
                else {
                    HDfprintf(stream, "%*s%-*s %Zu\n", indent, "", fwidth,
                              "User-Defined Link Size:", lnk->u.ud.size);
                } /* end else */
            } /* end if */
            else
                HGOTO_ERROR(H5E_SYM, H5E_BADVALUE, FAIL, "unrecognized link type")
            break;
    } /* end switch */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5O__link_debug() */