summaryrefslogtreecommitdiffstats
path: root/src/H5Dio.c
blob: 026f64e1249d6f7b0f7b682161b792383aa981e4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * 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.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

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

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


/***********/
/* Headers */
/***********/
#include "H5private.h"          /* Generic Functions                        */
#include "H5CXprivate.h"        /* API Contexts                             */
#include "H5Dpkg.h"             /* Dataset functions                        */
#include "H5Eprivate.h"         /* Error handling                           */
#include "H5FLprivate.h"        /* Free Lists                               */
#include "H5Iprivate.h"         /* IDs                                      */
#include "H5MMprivate.h"        /* Memory management                        */
#include "H5Sprivate.h"         /* Dataspace                                */
#include "H5VLnative.h"         /* Native VOL connector                     */

#ifdef H5_HAVE_PARALLEL
/* Remove this if H5R_DATASET_REGION is no longer used in this file */
#include "H5Rpublic.h"
#endif /*H5_HAVE_PARALLEL*/


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


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


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

/* Setup/teardown routines */
static herr_t H5D__ioinfo_init(H5D_t *dset, const H5D_type_info_t *type_info,
    H5D_storage_t *store, H5D_io_info_t *io_info);
static herr_t H5D__typeinfo_init(const H5D_t *dset, hid_t mem_type_id,
    hbool_t do_write, H5D_type_info_t *type_info);
#ifdef H5_HAVE_PARALLEL
static herr_t H5D__ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset,
    const H5S_t *file_space, const H5S_t *mem_space, const H5D_type_info_t *type_info);
#endif /* H5_HAVE_PARALLEL */
static herr_t H5D__typeinfo_term(const H5D_type_info_t *type_info);


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


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

/* Declare a free list to manage blocks of type conversion data */
H5FL_BLK_DEFINE(type_conv);

/* Declare a free list to manage the H5D_chunk_map_t struct */
H5FL_DEFINE(H5D_chunk_map_t);



/*-------------------------------------------------------------------------
 * Function:    H5D__get_offset_copy
 *
 * Purpose:     Copies an offset buffer and performs bounds checks on the
 *              values.
 *
 *              This helper function ensures that the offset buffer given
 *              by the user is suitable for use with the rest of the library.
 *
 * Return:      SUCCEED/FAIL
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__get_offset_copy(const H5D_t *dset, const hsize_t *offset, hsize_t *offset_copy)
{
    unsigned u;
    herr_t ret_value = SUCCEED;     /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

    HDassert(dset);
    HDassert(offset);
    HDassert(offset_copy);

    /* The library's chunking code requires the offset to terminate with a zero.
     * So transfer the offset array to an internal offset array that we
     * can properly terminate (handled via the calloc call).
     */

    HDmemset(offset_copy, 0, H5O_LAYOUT_NDIMS * sizeof(hsize_t));

    for (u = 0; u < dset->shared->ndims; u++) {
        /* Make sure the offset doesn't exceed the dataset's dimensions */
        if (offset[u] > dset->shared->curr_dims[u])
            HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "offset exceeds dimensions of dataset")

        /* Make sure the offset fall right on a chunk's boundary */
        if (offset[u] % dset->shared->layout.u.chunk.dim[u])
            HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "offset doesn't fall on chunks's boundary")

        offset_copy[u] = offset[u];
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)

} /* end H5D__get_offset_copy() */


/*-------------------------------------------------------------------------
 * Function:    H5Dread
 *
 * Purpose:     Reads (part of) a DSET from the file into application
 *              memory BUF. The part of the dataset to read is defined with
 *              MEM_SPACE_ID and FILE_SPACE_ID. The data points are
 *              converted from their file type to the MEM_TYPE_ID specified.
 *              Additional miscellaneous data transfer properties can be
 *              passed to this function with the PLIST_ID argument.
 *
 *              The FILE_SPACE_ID can be the constant H5S_ALL which indicates
 *              that the entire file dataspace is to be referenced.
 *
 *              The MEM_SPACE_ID can be the constant H5S_ALL in which case
 *              the memory dataspace is the same as the file dataspace
 *              defined when the dataset was created.
 *
 *              The number of elements in the memory dataspace must match
 *              the number of elements in the file dataspace.
 *
 *              The PLIST_ID can be the constant H5P_DEFAULT in which
 *              case the default data transfer properties are used.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Robb Matzke
 *              Thursday, December 4, 1997
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
    hid_t file_space_id, hid_t dxpl_id, void *buf/*out*/)
{
    H5VL_object_t  *vol_obj     = NULL;
    herr_t          ret_value   = SUCCEED;      /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE6("e", "iiiiix", dset_id, mem_type_id, mem_space_id, file_space_id,
             dxpl_id, buf);

    /* Check arguments */
    if (mem_space_id < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid memory dataspace ID")
    if (file_space_id < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid file dataspace ID")

    /* Get dataset pointer */
    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(dset_id, H5I_DATASET)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "dset_id is not a dataset ID")

    /* Get the default dataset transfer property list if the user didn't provide one */
    if (H5P_DEFAULT == dxpl_id)
        dxpl_id = H5P_DATASET_XFER_DEFAULT;
    else
        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")

    /* Set DXPL for operation */
    H5CX_set_dxpl(dxpl_id);

    /* Read the data */
    if ((ret_value = H5VL_dataset_read(vol_obj, mem_type_id, mem_space_id, file_space_id, dxpl_id, buf, H5_REQUEST_NULL)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read data")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Dread() */


/*-------------------------------------------------------------------------
 * Function:    H5Dread_chunk
 *
 * Purpose:     Reads an entire chunk from the file directly.
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:  Matthew Strong (GE Healthcare)
 *              14 February 2016
 *
 *---------------------------------------------------------------------------
 */
herr_t
H5Dread_chunk(hid_t dset_id, hid_t dxpl_id, const hsize_t *offset, uint32_t *filters,
         void *buf)
{
    H5VL_object_t  *vol_obj = NULL;
    herr_t          ret_value = SUCCEED;            /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE5("e", "ii*h*Iu*x", dset_id, dxpl_id, offset, filters, buf);

    /* Check arguments */
    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(dset_id, H5I_DATASET)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "dset_id is not a dataset ID")
    if (!buf)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "buf cannot be NULL")
    if (!offset)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset cannot be NULL")
    if (!filters)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "filters cannot be NULL")

    /* Get the default dataset transfer property list if the user didn't provide one */
    if (H5P_DEFAULT == dxpl_id)
        dxpl_id = H5P_DATASET_XFER_DEFAULT;
    else
        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "dxpl_id is not a dataset transfer property list ID")

    /* Set DXPL for operation */
    H5CX_set_dxpl(dxpl_id);

    /* Read the raw chunk */
    if(H5VL_dataset_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_NATIVE_DATASET_CHUNK_READ, offset, filters, buf) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read unprocessed chunk data")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Dread_chunk() */


/*-------------------------------------------------------------------------
 * Function:    H5Dwrite
 *
 * Purpose:     Writes (part of) a DSET from application memory BUF to the
 *              file. The part of the dataset to write is defined with the
 *              MEM_SPACE_ID and FILE_SPACE_ID arguments. The data points
 *              are converted from their current type (MEM_TYPE_ID) to their
 *              file datatype. Additional miscellaneous data transfer
 *              properties can be passed to this function with the
 *              PLIST_ID argument.
 *
 *              The FILE_SPACE_ID can be the constant H5S_ALL which indicates
 *              that the entire file dataspace is to be referenced.
 *
 *              The MEM_SPACE_ID can be the constant H5S_ALL in which case
 *              the memory dataspace is the same as the file dataspace
 *              defined when the dataset was created.
 *
 *              The number of elements in the memory dataspace must match
 *              the number of elements in the file dataspace.
 *
 *              The PLIST_ID can be the constant H5P_DEFAULT in which
 *              case the default data transfer properties are used.
 *
 * Return:      SUCCEED/FAIL
 *
 * Programmer:  Robb Matzke
 *              Thursday, December 4, 1997
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
	 hid_t file_space_id, hid_t dxpl_id, const void *buf)
{
    H5VL_object_t          *vol_obj = NULL;
    herr_t                  ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE6("e", "iiiii*x", dset_id, mem_type_id, mem_space_id, file_space_id,
             dxpl_id, buf);

    /* Check arguments */
    if (mem_space_id < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid memory dataspace ID")
    if (file_space_id < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid file dataspace ID")

    /* Get dataset pointer */
    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(dset_id, H5I_DATASET)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "dset_id is not a dataset ID")

    /* Get the default dataset transfer property list if the user didn't provide one */
    if (H5P_DEFAULT == dxpl_id)
        dxpl_id = H5P_DATASET_XFER_DEFAULT;
    else
        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")

    /* Set DXPL for operation */
    H5CX_set_dxpl(dxpl_id);

    /* Write the data */
    if ((ret_value = H5VL_dataset_write(vol_obj, mem_type_id, mem_space_id, file_space_id, dxpl_id, buf, H5_REQUEST_NULL)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write data")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Dwrite() */


/*-------------------------------------------------------------------------
 * Function:    H5Dwrite_chunk
 *
 * Purpose:     Writes an entire chunk to the file directly.	
 *
 * Return:      Non-negative on success/Negative on failure
 *
 * Programmer:	Raymond Lu
 *		        30 July 2012
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Dwrite_chunk(hid_t dset_id, hid_t dxpl_id, uint32_t filters, const hsize_t *offset, 
         size_t data_size, const void *buf)
{
    H5VL_object_t  *vol_obj = NULL;
    uint32_t        data_size_32;                   /* Chunk data size (limited to 32-bits currently) */
    herr_t          ret_value = SUCCEED;            /* Return value */
    
    FUNC_ENTER_API(FAIL)
    H5TRACE6("e", "iiIu*hz*x", dset_id, dxpl_id, filters, offset, data_size, buf);

    /* Check arguments */
    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(dset_id, H5I_DATASET)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset ID")
    if (!buf)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "buf cannot be NULL")
    if (!offset)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset cannot be NULL")
    if (0 == data_size)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "data_size cannot be zero")

    /* Make sure data size is less than 4 GiB */
    data_size_32 = (uint32_t)data_size;
    if (data_size != (size_t)data_size_32)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid data_size - chunks cannot be > 4 GiB")

    /* Get the default dataset transfer property list if the user didn't provide one */
    if (H5P_DEFAULT == dxpl_id)
        dxpl_id = H5P_DATASET_XFER_DEFAULT;
    else
        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "dxpl_id is not a dataset transfer property list ID")

    /* Set DXPL for operation */
    H5CX_set_dxpl(dxpl_id);

    /* Write chunk */
    if(H5VL_dataset_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_NATIVE_DATASET_CHUNK_WRITE, filters, offset, data_size_32, buf) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write unprocessed chunk data")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Dwrite_chunk() */


/*-------------------------------------------------------------------------
 * Function:	H5D__read
 *
 * Purpose:	Reads (part of) a DATASET into application memory BUF. See
 *		H5Dread() for complete details.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Thursday, December  4, 1997
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__read(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
    const H5S_t *file_space, void *buf/*out*/)
{
    H5D_chunk_map_t *fm = NULL;         /* Chunk file<->memory mapping */
    H5D_io_info_t io_info;              /* Dataset I/O info     */
    H5D_type_info_t type_info;          /* Datatype info for operation */
    hbool_t type_info_init = FALSE;     /* Whether the datatype info has been initialized */
    H5S_t * projected_mem_space = NULL; /* If not NULL, ptr to dataspace containing a     */
                                        /* projection of the supplied mem_space to a new  */
                                        /* dataspace with rank equal to that of           */
                                        /* file_space.                                    */
                                        /*                                                */
                                        /* This field is only used if                     */
                                        /* H5S_select_shape_same() returns TRUE when      */
                                        /* comparing the mem_space and the data_space,    */
                                        /* and the mem_space have different rank.         */
                                        /*                                                */
                                        /* Note that if this variable is used, the        */
                                        /* projected mem space must be discarded at the   */
                                        /* end of the function to avoid a memory leak.    */
    H5D_storage_t store;                /*union of EFL and chunk pointer in file space */
    hssize_t	snelmts;                /*total number of elmts	(signed) */
    hsize_t	nelmts;                 /*total number of elmts	*/
    hbool_t     io_op_init = FALSE;     /* Whether the I/O op has been initialized */
    char        fake_char;              /* Temporary variable for NULL buffer pointers */
    herr_t	ret_value = SUCCEED;	/* Return value	*/

    FUNC_ENTER_PACKAGE_TAG(dataset->oloc.addr)

    /* check args */
    HDassert(dataset && dataset->oloc.file);

    if(!file_space)
        file_space = dataset->shared->space;
    if(!mem_space)
        mem_space = file_space;
    if((snelmts = H5S_GET_SELECT_NPOINTS(mem_space)) < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "dst dataspace has invalid selection")
    H5_CHECKED_ASSIGN(nelmts, hsize_t, snelmts, hssize_t);

    /* Set up datatype info for operation */
    if(H5D__typeinfo_init(dataset, mem_type_id, FALSE, &type_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to set up type info")
    type_info_init = TRUE;

#ifdef H5_HAVE_PARALLEL
    /* Check for non-MPI-based VFD */
    if(!(H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI))) {
        H5FD_mpio_xfer_t io_xfer_mode;      /* MPI I/O transfer mode */

        /* Get I/O transfer mode */
        if(H5CX_get_io_xfer_mode(&io_xfer_mode) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")

        /* Collective access is not permissible without a MPI based VFD */
        if(io_xfer_mode == H5FD_MPIO_COLLECTIVE)
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPI-based drivers only")
    } /* end if */
#endif /*H5_HAVE_PARALLEL*/

    /* Make certain that the number of elements in each selection is the same */
    if(nelmts != (hsize_t)H5S_GET_SELECT_NPOINTS(file_space))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "src and dest dataspaces have different number of elements selected")

    /* Check for a NULL buffer, after the H5S_ALL dataspace selection has been handled */
    if(NULL == buf) {
        /* Check for any elements selected (which is invalid) */
        if(nelmts > 0)
            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer")

	/* If the buffer is nil, and 0 element is selected, make a fake buffer.
	 * This is for some MPI package like ChaMPIon on NCSA's tungsten which
	 * doesn't support this feature.
	 */
        buf = &fake_char;
    } /* end if */

    /* Make sure that both selections have their extents set */
    if(!(H5S_has_extent(file_space)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "file dataspace does not have extent set")
    if(!(H5S_has_extent(mem_space)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "memory dataspace does not have extent set")

    /* H5S_select_shape_same() has been modified to accept topologically identical
     * selections with different rank as having the same shape (if the most 
     * rapidly changing coordinates match up), but the I/O code still has 
     * difficulties with the notion.
     *
     * To solve this, we check to see if H5S_select_shape_same() returns true, 
     * and if the ranks of the mem and file spaces are different.  If the are, 
     * construct a new mem space that is equivalent to the old mem space, and 
     * use that instead.
     *
     * Note that in general, this requires us to touch up the memory buffer as 
     * well.
     */
    if(TRUE == H5S_select_shape_same(mem_space, file_space) &&
            H5S_GET_EXTENT_NDIMS(mem_space) != H5S_GET_EXTENT_NDIMS(file_space)) {
        void *adj_buf = NULL;   /* Pointer to the location in buf corresponding  */
                                /* to the beginning of the projected mem space.  */

        /* Attempt to construct projected dataspace for memory dataspace */
        if(H5S_select_construct_projection(mem_space, &projected_mem_space,
                (unsigned)H5S_GET_EXTENT_NDIMS(file_space), buf, (const void **)&adj_buf, type_info.dst_type_size) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to construct projected memory dataspace")
        HDassert(projected_mem_space);
        HDassert(adj_buf);

        /* Switch to using projected memory dataspace & adjusted buffer */
        mem_space = projected_mem_space;
        buf = adj_buf;
    } /* end if */


    /* Retrieve dataset properties */
    /* <none needed in the general case> */

    /* If space hasn't been allocated and not using external storage,
     * return fill value to buffer if fill time is upon allocation, or
     * do nothing if fill time is never.  If the dataset is compact and
     * fill time is NEVER, there is no way to tell whether part of data
     * has been overwritten.  So just proceed in reading.
     */
    if(nelmts > 0 && dataset->shared->dcpl_cache.efl.nused == 0 &&
            !(*dataset->shared->layout.ops->is_space_alloc)(&dataset->shared->layout.storage)) {
        H5D_fill_value_t fill_status;   /* Whether/How the fill value is defined */

        /* Retrieve dataset's fill-value properties */
        if(H5P_is_fill_value_defined(&dataset->shared->dcpl_cache.fill, &fill_status) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined")

        /* Should be impossible, but check anyway... */
        if(fill_status == H5D_FILL_VALUE_UNDEFINED &&
                (dataset->shared->dcpl_cache.fill.fill_time == H5D_FILL_TIME_ALLOC || dataset->shared->dcpl_cache.fill.fill_time == H5D_FILL_TIME_IFSET))
            HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "read failed: dataset doesn't exist, no data can be read")

        /* If we're never going to fill this dataset, just leave the junk in the user's buffer */
        if(dataset->shared->dcpl_cache.fill.fill_time == H5D_FILL_TIME_NEVER)
            HGOTO_DONE(SUCCEED)

        /* Go fill the user's selection with the dataset's fill value */
        if(H5D__fill(dataset->shared->dcpl_cache.fill.buf, dataset->shared->type, buf, type_info.mem_type, mem_space) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "filling buf failed")
        else
            HGOTO_DONE(SUCCEED)
    } /* end if */

    /* Set up I/O operation */
    io_info.op_type = H5D_IO_OP_READ;
    io_info.u.rbuf = buf;
    if(H5D__ioinfo_init(dataset, &type_info, &store, &io_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "unable to set up I/O operation")

    /* Sanity check that space is allocated, if there are elements */
    if(nelmts > 0)
        HDassert((*dataset->shared->layout.ops->is_space_alloc)(&dataset->shared->layout.storage)
                || dataset->shared->dcpl_cache.efl.nused > 0
                || dataset->shared->layout.type == H5D_COMPACT);

    /* Allocate the chunk map */
    if(NULL == (fm = H5FL_CALLOC(H5D_chunk_map_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate chunk map")

    /* Call storage method's I/O initialization routine */
    if(io_info.layout_ops.io_init && (*io_info.layout_ops.io_init)(&io_info, &type_info, nelmts, file_space, mem_space, fm) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't initialize I/O info")
    io_op_init = TRUE;

#ifdef H5_HAVE_PARALLEL
    /* Adjust I/O info for any parallel I/O */
    if(H5D__ioinfo_adjust(&io_info, dataset, file_space, mem_space, &type_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to adjust I/O info for parallel I/O")
#endif /*H5_HAVE_PARALLEL*/

    /* Invoke correct "high level" I/O routine */
    if((*io_info.io_ops.multi_read)(&io_info, &type_info, nelmts, file_space, mem_space, fm) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read data")

done:
    /* Shut down the I/O op information */
    if(io_op_init && io_info.layout_ops.io_term && (*io_info.layout_ops.io_term)(fm) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down I/O op info")
    if(fm)
        fm = H5FL_FREE(H5D_chunk_map_t, fm);

    /* Shut down datatype info for operation */
    if(type_info_init && H5D__typeinfo_term(&type_info) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down type info")

    /* discard projected mem space if it was created */
    if(NULL != projected_mem_space)
        if(H5S_close(projected_mem_space) < 0)
            HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down projected memory dataspace")

    FUNC_LEAVE_NOAPI_TAG(ret_value)
} /* end H5D__read() */


/*-------------------------------------------------------------------------
 * Function:	H5D__write
 *
 * Purpose:	Writes (part of) a DATASET to a file from application memory
 *		BUF. See H5Dwrite() for complete details.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Thursday, December  4, 1997
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__write(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
    const H5S_t *file_space, const void *buf)
{
    H5D_chunk_map_t *fm = NULL;         /* Chunk file<->memory mapping */
    H5D_io_info_t io_info;              /* Dataset I/O info     */
    H5D_type_info_t type_info;          /* Datatype info for operation */
    hbool_t type_info_init = FALSE;     /* Whether the datatype info has been initialized */
    H5S_t * projected_mem_space = NULL; /* If not NULL, ptr to dataspace containing a     */
                                        /* projection of the supplied mem_space to a new  */
                                        /* dataspace with rank equal to that of           */
                                        /* file_space.                                    */
                                        /*                                                */
                                        /* This field is only used if                     */
                                        /* H5S_select_shape_same() returns TRUE when      */
                                        /* comparing the mem_space and the data_space,    */
                                        /* and the mem_space have different rank.         */
                                        /*                                                */
                                        /* Note that if this variable is used, the        */
                                        /* projected mem space must be discarded at the   */
                                        /* end of the function to avoid a memory leak.    */
    H5D_storage_t store;                /*union of EFL and chunk pointer in file space */
    hssize_t	snelmts;                /*total number of elmts	(signed) */
    hsize_t	nelmts;                 /*total number of elmts	*/
    hbool_t     io_op_init = FALSE;     /* Whether the I/O op has been initialized */
    char        fake_char;              /* Temporary variable for NULL buffer pointers */
    herr_t	ret_value = SUCCEED;	/* Return value	*/

    FUNC_ENTER_PACKAGE_TAG(dataset->oloc.addr)

    /* check args */
    HDassert(dataset && dataset->oloc.file);

    /* All filters in the DCPL must have encoding enabled. */
    if(!dataset->shared->checked_filters) {
        if(H5Z_can_apply(dataset->shared->dcpl_id, dataset->shared->type_id) < 0)
            HGOTO_ERROR(H5E_PLINE, H5E_CANAPPLY, FAIL, "can't apply filters")

        dataset->shared->checked_filters = TRUE;
    } /* end if */

    /* Check if we are allowed to write to this file */
    if(0 == (H5F_INTENT(dataset->oloc.file) & H5F_ACC_RDWR))
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "no write intent on file")

    /* Set up datatype info for operation */
    if(H5D__typeinfo_init(dataset, mem_type_id, TRUE, &type_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to set up type info")
    type_info_init = TRUE;

    /* Various MPI based checks */
#ifdef H5_HAVE_PARALLEL
    if H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI) {
        /* If MPI based VFD is used, no VL datatype support yet. */
        /* This is because they use the global heap in the file and we don't */
        /* support parallel access of that yet */
        if(H5T_detect_class(type_info.mem_type, H5T_VLEN, FALSE) > 0)
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing VL datatypes yet")

        /* If MPI based VFD is used, no VL datatype support yet. */
        /* This is because they use the global heap in the file and we don't */
        /* support parallel access of that yet */
        /* We should really use H5T_detect_class() here, but it will be difficult
         * to detect the type of the reference if it is nested... -QAK
         */
        if(H5T_get_class(type_info.mem_type, TRUE) == H5T_REFERENCE &&
                H5T_get_ref_type(type_info.mem_type) == H5R_DATASET_REGION)
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing region reference datatypes yet")
    } /* end if */
    else {
        H5FD_mpio_xfer_t io_xfer_mode;      /* MPI I/O transfer mode */

        /* Get I/O transfer mode */
        if(H5CX_get_io_xfer_mode(&io_xfer_mode) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")

        /* Collective access is not permissible without a MPI based VFD */
        if(io_xfer_mode == H5FD_MPIO_COLLECTIVE)
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPI-based driver only")
    } /* end else */
#endif /*H5_HAVE_PARALLEL*/

    /* Initialize dataspace information */
    if(!file_space)
        file_space = dataset->shared->space;
    if(!mem_space)
        mem_space = file_space;

    if((snelmts = H5S_GET_SELECT_NPOINTS(mem_space)) < 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "src dataspace has invalid selection")
    H5_CHECKED_ASSIGN(nelmts, hsize_t, snelmts, hssize_t);

    /* Make certain that the number of elements in each selection is the same */
    if(nelmts != (hsize_t)H5S_GET_SELECT_NPOINTS(file_space))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "src and dest dataspaces have different number of elements selected")

    /* Check for a NULL buffer, after the H5S_ALL dataspace selection has been handled */
    if(NULL == buf) {
        /* Check for any elements selected (which is invalid) */
        if(nelmts > 0)
            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer")

	/* If the buffer is nil, and 0 element is selected, make a fake buffer.
	 * This is for some MPI package like ChaMPIon on NCSA's tungsten which
	 * doesn't support this feature.
	 */
        buf = &fake_char;
    } /* end if */

    /* Make sure that both selections have their extents set */
    if(!(H5S_has_extent(file_space)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "file dataspace does not have extent set")
    if(!(H5S_has_extent(mem_space)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "memory dataspace does not have extent set")

    /* H5S_select_shape_same() has been modified to accept topologically 
     * identical selections with different rank as having the same shape 
     * (if the most rapidly changing coordinates match up), but the I/O 
     * code still has difficulties with the notion.
     *
     * To solve this, we check to see if H5S_select_shape_same() returns 
     * true, and if the ranks of the mem and file spaces are different.  
     * If the are, construct a new mem space that is equivalent to the 
     * old mem space, and use that instead.
     *
     * Note that in general, this requires us to touch up the memory buffer 
     * as well.
     */
    if(TRUE == H5S_select_shape_same(mem_space, file_space) &&
            H5S_GET_EXTENT_NDIMS(mem_space) != H5S_GET_EXTENT_NDIMS(file_space)) {
        void *adj_buf = NULL;   /* Pointer to the location in buf corresponding  */
                                /* to the beginning of the projected mem space.  */

        /* Attempt to construct projected dataspace for memory dataspace */
        if(H5S_select_construct_projection(mem_space, &projected_mem_space,
                (unsigned)H5S_GET_EXTENT_NDIMS(file_space), buf, (const void **)&adj_buf, type_info.src_type_size) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to construct projected memory dataspace")
        HDassert(projected_mem_space);
        HDassert(adj_buf);

        /* Switch to using projected memory dataspace & adjusted buffer */
        mem_space = projected_mem_space;
        buf = adj_buf;
    } /* end if */

    /* Retrieve dataset properties */
    /* <none needed currently> */

    /* Set up I/O operation */
    io_info.op_type = H5D_IO_OP_WRITE;
    io_info.u.wbuf = buf;
    if(H5D__ioinfo_init(dataset, &type_info, &store, &io_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to set up I/O operation")

    /* Allocate dataspace and initialize it if it hasn't been. */
    if(nelmts > 0 && dataset->shared->dcpl_cache.efl.nused == 0 &&
            !(*dataset->shared->layout.ops->is_space_alloc)(&dataset->shared->layout.storage)) {
        hssize_t file_nelmts;   /* Number of elements in file dataset's dataspace */
        hbool_t full_overwrite; /* Whether we are over-writing all the elements */

        /* Get the number of elements in file dataset's dataspace */
        if((file_nelmts = H5S_GET_EXTENT_NPOINTS(file_space)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "can't retrieve number of elements in file dataset")

        /* Always allow fill values to be written if the dataset has a VL datatype */
        if(H5T_detect_class(dataset->shared->type, H5T_VLEN, FALSE))
            full_overwrite = FALSE;
        else
            full_overwrite = (hbool_t)((hsize_t)file_nelmts == nelmts ? TRUE : FALSE);

        /* Allocate storage */
        if(H5D__alloc_storage(&io_info, H5D_ALLOC_WRITE, full_overwrite, NULL) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize storage")
    } /* end if */

    /* Allocate the chunk map */
    if(NULL == (fm = H5FL_CALLOC(H5D_chunk_map_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate chunk map")

    /* Call storage method's I/O initialization routine */
    if(io_info.layout_ops.io_init && (*io_info.layout_ops.io_init)(&io_info, &type_info, nelmts, file_space, mem_space, fm) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't initialize I/O info")
    io_op_init = TRUE;

#ifdef H5_HAVE_PARALLEL
    /* Adjust I/O info for any parallel I/O */
    if(H5D__ioinfo_adjust(&io_info, dataset, file_space, mem_space, &type_info) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to adjust I/O info for parallel I/O")
#endif /*H5_HAVE_PARALLEL*/

    /* Invoke correct "high level" I/O routine */
    if((*io_info.io_ops.multi_write)(&io_info, &type_info, nelmts, file_space, mem_space, fm) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write data")

#ifdef OLD_WAY
/*
 * This was taken out because it can be called in a parallel program with
 * independent access, causing the metadata cache to get corrupted. Its been
 * disabled for all types of access (serial as well as parallel) to make the
 * modification time consistent for all programs. -QAK
 *
 * We should set a value in the dataset's shared information instead and flush
 * it to the file when the dataset is being closed. -QAK
 */
    /*
     * Update modification time.  We have to do this explicitly because
     * writing to a dataset doesn't necessarily change the object header.
     */
    if(H5O_touch(&(dataset->oloc), FALSE) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update modification time")
#endif /* OLD_WAY */

done:
    /* Shut down the I/O op information */
    if(io_op_init && io_info.layout_ops.io_term && (*io_info.layout_ops.io_term)(fm) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down I/O op info")
    if(fm)
        fm = H5FL_FREE(H5D_chunk_map_t, fm);

    /* Shut down datatype info for operation */
    if(type_info_init && H5D__typeinfo_term(&type_info) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down type info")

    /* discard projected mem space if it was created */
    if(NULL != projected_mem_space)
        if(H5S_close(projected_mem_space) < 0)
            HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "unable to shut down projected memory dataspace")

    FUNC_LEAVE_NOAPI_TAG(ret_value)
} /* end H5D__write() */


/*-------------------------------------------------------------------------
 * Function:	H5D__ioinfo_init
 *
 * Purpose:	Routine for determining correct I/O operations for
 *              each I/O action.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Thursday, September 30, 2004
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__ioinfo_init(H5D_t *dset, const H5D_type_info_t *type_info,
    H5D_storage_t *store, H5D_io_info_t *io_info)
{
    FUNC_ENTER_STATIC_NOERR

    /* check args */
    HDassert(dset);
    HDassert(dset->oloc.file);
    HDassert(type_info);
    HDassert(type_info->tpath);
    HDassert(io_info);

    /* Set up "normal" I/O fields */
    io_info->dset = dset;
    io_info->store = store;

    /* Set I/O operations to initial values */
    io_info->layout_ops = *dset->shared->layout.ops;

    /* Set the "high-level" I/O operations for the dataset */
    io_info->io_ops.multi_read = dset->shared->layout.ops->ser_read;
    io_info->io_ops.multi_write = dset->shared->layout.ops->ser_write;

    /* Set the I/O operations for reading/writing single blocks on disk */
    if(type_info->is_xform_noop && type_info->is_conv_noop) {
        /*
         * If there is no data transform or type conversion then read directly into
         *  the application's buffer.  This saves at least one mem-to-mem copy.
         */
        io_info->io_ops.single_read = H5D__select_read;
        io_info->io_ops.single_write = H5D__select_write;
    } /* end if */
    else {
        /*
         * This is the general case (type conversion, usually).
         */
        io_info->io_ops.single_read = H5D__scatgath_read;
        io_info->io_ops.single_write = H5D__scatgath_write;
    } /* end else */

#ifdef H5_HAVE_PARALLEL
    /* Determine if the file was opened with an MPI VFD */
    io_info->using_mpi_vfd = H5F_HAS_FEATURE(dset->oloc.file, H5FD_FEAT_HAS_MPI);
#endif /* H5_HAVE_PARALLEL */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5D__ioinfo_init() */


/*-------------------------------------------------------------------------
 * Function:	H5D__typeinfo_init
 *
 * Purpose:	Routine for determining correct datatype information for
 *              each I/O action.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Tuesday, March  4, 2008
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__typeinfo_init(const H5D_t *dset, hid_t mem_type_id, hbool_t do_write,
    H5D_type_info_t *type_info)
{
    const H5T_t	*src_type;              /* Source datatype */
    const H5T_t	*dst_type;              /* Destination datatype */
    H5Z_data_xform_t *data_transform;   /* Data transform info */
    herr_t ret_value = SUCCEED;	        /* Return value	*/

    FUNC_ENTER_STATIC

    /* check args */
    HDassert(type_info);
    HDassert(dset);

    /* Patch the top level file pointer for dt->shared->u.vlen.f if needed */
    if(H5T_patch_vlen_file(dset->shared->type, dset->oloc.file) < 0 )
        HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "can't patch VL datatype file pointer")

    /* Initialize type info safely */
    HDmemset(type_info, 0, sizeof(*type_info));

    /* Get the memory & dataset datatypes */
    if(NULL == (type_info->mem_type = (const H5T_t *)H5I_object_verify(mem_type_id, H5I_DATATYPE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a datatype")
    type_info->dset_type = dset->shared->type;

    if(do_write) {
        src_type = type_info->mem_type;
        dst_type = dset->shared->type;
        type_info->src_type_id = mem_type_id;
        type_info->dst_type_id = dset->shared->type_id;
    } /* end if */
    else {
        src_type = dset->shared->type;
        dst_type = type_info->mem_type;
        type_info->src_type_id = dset->shared->type_id;
        type_info->dst_type_id = mem_type_id;
    } /* end else */

    /* Locate the type conversion function and dataspace conversion
     * functions, and set up the element numbering information. If a data
     * type conversion is necessary then register datatype atoms. Data type
     * conversion is necessary if the user has set the `need_bkg' to a high
     * enough value in xfer_parms since turning off datatype conversion also
     * turns off background preservation.
     */
    if(NULL == (type_info->tpath = H5T_path_find(src_type, dst_type)))
        HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "unable to convert between src and dest datatype")

    /* Retrieve info from API context */
    if(H5CX_get_data_transform(&data_transform) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get data transform info")

    /* Precompute some useful information */
    type_info->src_type_size = H5T_get_size(src_type);
    type_info->dst_type_size = H5T_get_size(dst_type);
    type_info->max_type_size = MAX(type_info->src_type_size, type_info->dst_type_size);
    type_info->is_conv_noop = H5T_path_noop(type_info->tpath);
    type_info->is_xform_noop = H5Z_xform_noop(data_transform);
    if(type_info->is_xform_noop && type_info->is_conv_noop) {
        type_info->cmpd_subset = NULL;
        type_info->need_bkg = H5T_BKG_NO;
    } /* end if */
    else {
        void	*tconv_buf;		/* Temporary conversion buffer pointer */
        void	*bkgr_buf;		/* Background conversion buffer pointer */
        size_t	max_temp_buf;		/* Maximum temporary buffer size */
        H5T_bkg_t bkgr_buf_type;        /* Background buffer type */
        size_t	target_size;		/* Desired buffer size	*/

        /* Get info from API context */
        if(H5CX_get_max_temp_buf(&max_temp_buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve max. temp. buf size")
        if(H5CX_get_tconv_buf(&tconv_buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve temp. conversion buffer pointer")
        if(H5CX_get_bkgr_buf(&bkgr_buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve background conversion buffer pointer")
        if(H5CX_get_bkgr_buf_type(&bkgr_buf_type) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve background buffer type")

        /* Check if the datatypes are compound subsets of one another */
        type_info->cmpd_subset = H5T_path_compound_subset(type_info->tpath);

        /* Check if we need a background buffer */
        if(do_write && H5T_detect_class(dset->shared->type, H5T_VLEN, FALSE))
            type_info->need_bkg = H5T_BKG_YES;
        else {
            H5T_bkg_t path_bkg;     /* Type conversion's background info */

            if((path_bkg = H5T_path_bkg(type_info->tpath))) {
                /* Retrieve the bkgr buffer property */
                type_info->need_bkg = bkgr_buf_type;
                type_info->need_bkg = MAX(path_bkg, type_info->need_bkg);
            } /* end if */
            else
                type_info->need_bkg = H5T_BKG_NO; /*never needed even if app says yes*/
        } /* end else */


        /* Set up datatype conversion/background buffers */

        target_size = max_temp_buf;

        /* If the buffer is too small to hold even one element, try to make it bigger */
        if(target_size < type_info->max_type_size) {
            hbool_t default_buffer_info;    /* Whether the buffer information are the defaults */

            /* Detect if we have all default settings for buffers */
            default_buffer_info = (hbool_t)((H5D_TEMP_BUF_SIZE == max_temp_buf)
                    && (NULL == tconv_buf) && (NULL == bkgr_buf));

            /* Check if we are using the default buffer info */
            if(default_buffer_info)
                /* OK to get bigger for library default settings */
                target_size = type_info->max_type_size;
            else
                /* Don't get bigger than the application has requested */
                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "temporary buffer max size is too small")
        } /* end if */

        /* Compute the number of elements that will fit into buffer */
        type_info->request_nelmts = target_size / type_info->max_type_size;

        /* Sanity check elements in temporary buffer */
        if(type_info->request_nelmts == 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "temporary buffer max size is too small")

        /*
         * Get a temporary buffer for type conversion unless the app has already
         * supplied one through the xfer properties. Instead of allocating a
         * buffer which is the exact size, we allocate the target size.  The
         * malloc() is usually less resource-intensive if we allocate/free the
         * same size over and over.
         */
        if(NULL == (type_info->tconv_buf = (uint8_t *)tconv_buf)) {
            /* Allocate temporary buffer */
            if(NULL == (type_info->tconv_buf = H5FL_BLK_MALLOC(type_conv, target_size)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion")
            type_info->tconv_buf_allocated = TRUE;
        } /* end if */
        if(type_info->need_bkg && NULL == (type_info->bkg_buf = (uint8_t *)bkgr_buf)) {
            size_t	bkg_size;		/* Desired background buffer size	*/

            /* Compute the background buffer size */
            /* (don't try to use buffers smaller than the default size) */
            bkg_size = type_info->request_nelmts * type_info->dst_type_size;
            if(bkg_size < max_temp_buf)
                bkg_size = max_temp_buf;

            /* Allocate background buffer */
            /* (Need calloc()-like call since memory needs to be initialized) */
            if(NULL == (type_info->bkg_buf = H5FL_BLK_CALLOC(type_conv, bkg_size)))
                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for background conversion")
            type_info->bkg_buf_allocated = TRUE;
        } /* end if */
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__typeinfo_init() */

#ifdef H5_HAVE_PARALLEL

/*-------------------------------------------------------------------------
 * Function:	H5D__ioinfo_adjust
 *
 * Purpose:	Adjust operation's I/O info for any parallel I/O
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Thursday, March 27, 2008
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset,
    const H5S_t *file_space, const H5S_t *mem_space,
    const H5D_type_info_t *type_info)
{
    herr_t	ret_value = SUCCEED;	/* Return value	*/

    FUNC_ENTER_STATIC

    /* check args */
    HDassert(dset);
    HDassert(dset->oloc.file);
    HDassert(mem_space);
    HDassert(file_space);
    HDassert(type_info);
    HDassert(type_info->tpath);
    HDassert(io_info);

    /* Reset the actual io mode properties to the default values in case
     * the DXPL (if it's non-default) was previously used in a collective
     * I/O operation.
     */
    if(!H5CX_is_def_dxpl()) {
        H5CX_set_mpio_actual_chunk_opt(H5D_MPIO_NO_CHUNK_OPTIMIZATION);
        H5CX_set_mpio_actual_io_mode(H5D_MPIO_NO_COLLECTIVE);
    } /* end if */

    /* Make any parallel I/O adjustments */
    if(io_info->using_mpi_vfd) {
        H5FD_mpio_xfer_t xfer_mode; /* Parallel transfer for this request */
        htri_t opt;         /* Flag whether a selection is optimizable */

        /* Get the original state of parallel I/O transfer mode */
        if(H5CX_get_io_xfer_mode(&xfer_mode) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")

        /* Get MPI communicator */
        if(MPI_COMM_NULL == (io_info->comm = H5F_mpi_get_comm(dset->oloc.file)))
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "can't retrieve MPI communicator")

        /* Check if we can set direct MPI-IO read/write functions */
        if((opt = H5D__mpio_opt_possible(io_info, file_space, mem_space, type_info)) < 0)
            HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "invalid check for direct IO dataspace ")

        /* Check if we can use the optimized parallel I/O routines */
        if(opt == TRUE) {
            /* Override the I/O op pointers to the MPI-specific routines */
            io_info->io_ops.multi_read = dset->shared->layout.ops->par_read;
            io_info->io_ops.multi_write = dset->shared->layout.ops->par_write;
            io_info->io_ops.single_read = H5D__mpio_select_read;
            io_info->io_ops.single_write = H5D__mpio_select_write;
        } /* end if */
        else {
            /* Check if there are any filters in the pipeline. If there are,
             * we cannot break to independent I/O if this is a write operation;
             * otherwise there will be metadata inconsistencies in the file.
             */
            if (io_info->op_type == H5D_IO_OP_WRITE && io_info->dset->shared->dcpl_cache.pline.nused > 0) {
                H5D_mpio_no_collective_cause_t  cause;
                uint32_t                        local_no_collective_cause;
                uint32_t                        global_no_collective_cause;
                hbool_t                         local_error_message_previously_written = FALSE;
                hbool_t                         global_error_message_previously_written = FALSE;
                size_t                          index;
                char                            local_no_collective_cause_string[256] = "";
                char                            global_no_collective_cause_string[256] = "";
                const char                     *cause_strings[] = { "independent I/O was requested",
                                                                    "datatype conversions were required",
                                                                    "data transforms needed to be applied",
                                                                    "optimized MPI types flag wasn't set",
                                                                    "one of the dataspaces was neither simple nor scalar",
                                                                    "dataset was not contiguous or chunked",
                                                                    "parallel writes to filtered datasets are disabled" };

                if(H5CX_get_mpio_local_no_coll_cause(&local_no_collective_cause) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to get local no collective cause value")
                if(H5CX_get_mpio_global_no_coll_cause(&global_no_collective_cause) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to get global no collective cause value")

                /* Append each of the "reason for breaking collective I/O" error messages to the
                 * local and global no collective cause strings */
                for (cause = 1, index = 0; cause < H5D_MPIO_NO_COLLECTIVE_MAX_CAUSE; cause <<= 1, index++) {
                    size_t cause_strlen = HDstrlen(cause_strings[index]);

                    if (cause & local_no_collective_cause) {
                        /* Check if there were any previous error messages included. If so, prepend a semicolon
                         * to separate the messages.
                         */
                        if(local_error_message_previously_written)
                            HDstrncat(local_no_collective_cause_string, "; ", 2);

                        HDstrncat(local_no_collective_cause_string, cause_strings[index], cause_strlen);

                        local_error_message_previously_written = TRUE;
                    } /* end if */

                    if(cause & global_no_collective_cause) {
                        /* Check if there were any previous error messages included. If so, prepend a semicolon
                         * to separate the messages.
                         */
                        if(global_error_message_previously_written)
                            HDstrncat(global_no_collective_cause_string, "; ", 2);

                        HDstrncat(global_no_collective_cause_string, cause_strings[index], cause_strlen);

                        global_error_message_previously_written = TRUE;
                    } /* end if */
                } /* end for */

                HGOTO_ERROR(H5E_IO, H5E_NO_INDEPENDENT, FAIL, "Can't perform independent write with filters in pipeline.\n"
                                                              "    The following caused a break from collective I/O:\n"
                                                              "        Local causes: %s\n"
                                                              "        Global causes: %s",
                                                              local_no_collective_cause_string,
                                                              global_no_collective_cause_string);
            } /* end if */

            /* If we won't be doing collective I/O, but the user asked for
             * collective I/O, change the request to use independent I/O
             */
            if(xfer_mode == H5FD_MPIO_COLLECTIVE) {
                /* Change the xfer_mode to independent for handling the I/O */
                if(H5CX_set_io_xfer_mode(H5FD_MPIO_INDEPENDENT) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, FAIL, "can't set MPI-I/O transfer mode")
            } /* end if */
        } /* end else */
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__ioinfo_adjust() */
#endif /* H5_HAVE_PARALLEL */


/*-------------------------------------------------------------------------
 * Function:	H5D__typeinfo_term
 *
 * Purpose:	Common logic for terminating a type info object
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Thursday, March  6, 2008
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__typeinfo_term(const H5D_type_info_t *type_info)
{
    FUNC_ENTER_STATIC_NOERR

    /* Check for releasing datatype conversion & background buffers */
    if(type_info->tconv_buf_allocated) {
        HDassert(type_info->tconv_buf);
        (void)H5FL_BLK_FREE(type_conv, type_info->tconv_buf);
    } /* end if */
    if(type_info->bkg_buf_allocated) {
        HDassert(type_info->bkg_buf);
        (void)H5FL_BLK_FREE(type_conv, type_info->bkg_buf);
    } /* end if */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5D__typeinfo_term() */