aboutsummaryrefslogtreecommitdiff
path: root/block-vmdk.c
blob: 197fb5a620c011daeee51ae1c438e2d9995658a3 (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
/*
 * Block driver for the VMDK format
 *
 * Copyright (c) 2004 Fabrice Bellard
 * Copyright (c) 2005 Filip Navara
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "vl.h"
#include "block_int.h"

#define VMDK3_MAGIC (('C' << 24) | ('O' << 16) | ('W' << 8) | 'D')
#define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')

typedef struct {
    uint32_t version;
    uint32_t flags;
    uint32_t disk_sectors;
    uint32_t granularity;
    uint32_t l1dir_offset;
    uint32_t l1dir_size;
    uint32_t file_sectors;
    uint32_t cylinders;
    uint32_t heads;
    uint32_t sectors_per_track;
} VMDK3Header;

typedef struct {
    uint32_t version;
    uint32_t flags;
    int64_t capacity;
    int64_t granularity;
    int64_t desc_offset;
    int64_t desc_size;
    int32_t num_gtes_per_gte;
    int64_t rgd_offset;
    int64_t gd_offset;
    int64_t grain_offset;
    char filler[1];
    char check_bytes[4];
} __attribute__((packed)) VMDK4Header;

#define L2_CACHE_SIZE 16

typedef struct BDRVVmdkState {
    BlockDriverState *hd;
    int64_t l1_table_offset;
    int64_t l1_backup_table_offset;
    uint32_t *l1_table;
    uint32_t *l1_backup_table;
    unsigned int l1_size;
    uint32_t l1_entry_sectors;

    unsigned int l2_size;
    uint32_t *l2_cache;
    uint32_t l2_cache_offsets[L2_CACHE_SIZE];
    uint32_t l2_cache_counts[L2_CACHE_SIZE];

    unsigned int cluster_sectors;
    uint32_t parent_cid;
    int is_parent;
} BDRVVmdkState;

typedef struct VmdkMetaData {
    uint32_t offset;
    unsigned int l1_index;
    unsigned int l2_index;
    unsigned int l2_offset;
    int valid;
} VmdkMetaData;

typedef struct ActiveBDRVState{
    BlockDriverState *hd;            // active image handler
    uint64_t cluster_offset;         // current write offset
}ActiveBDRVState;

static ActiveBDRVState activeBDRV;


static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
{
    uint32_t magic;

    if (buf_size < 4)
        return 0;
    magic = be32_to_cpu(*(uint32_t *)buf);
    if (magic == VMDK3_MAGIC ||
        magic == VMDK4_MAGIC)
        return 100;
    else
        return 0;
}

#define CHECK_CID 1

#define SECTOR_SIZE 512			
#define DESC_SIZE 20*SECTOR_SIZE	// 20 sectors of 512 bytes each
#define HEADER_SIZE 512   			// first sector of 512 bytes

static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent)
{
    BDRVVmdkState *s = bs->opaque;
    char desc[DESC_SIZE];
    uint32_t cid;
    char *p_name, *cid_str;
    size_t cid_str_size;

    /* the descriptor offset = 0x200 */
    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)
        return 0;

    if (parent) {
        cid_str = "parentCID";
        cid_str_size = sizeof("parentCID");
    } else {
        cid_str = "CID";
        cid_str_size = sizeof("CID");
    }

    if ((p_name = strstr(desc,cid_str)) != 0) {
        p_name += cid_str_size;
        sscanf(p_name,"%x",&cid);
    }

    return cid;
}

static int vmdk_write_cid(BlockDriverState *bs, uint32_t cid)
{
    BDRVVmdkState *s = bs->opaque;
    char desc[DESC_SIZE], tmp_desc[DESC_SIZE];
    char *p_name, *tmp_str;

    /* the descriptor offset = 0x200 */
    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)
        return -1;

    tmp_str = strstr(desc,"parentCID");
    strcpy(tmp_desc, tmp_str);
    if ((p_name = strstr(desc,"CID")) != 0) {
        p_name += sizeof("CID");
        sprintf(p_name,"%x\n",cid);
        strcat(desc,tmp_desc);
    }

    if (bdrv_pwrite(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)
        return -1;
    return 0;
}

static int vmdk_is_cid_valid(BlockDriverState *bs)
{
#ifdef CHECK_CID
    BDRVVmdkState *s = bs->opaque;
    BlockDriverState *p_bs = s->hd->backing_hd;
    uint32_t cur_pcid;

    if (p_bs) {
        cur_pcid = vmdk_read_cid(p_bs,0);
        if (s->parent_cid != cur_pcid)
            // CID not valid
            return 0;
    }
#endif
    // CID valid
    return 1;
}

static int vmdk_snapshot_create(const char *filename, const char *backing_file)
{
    int snp_fd, p_fd;
    uint32_t p_cid;
    char *p_name, *gd_buf, *rgd_buf;
    const char *real_filename, *temp_str;
    VMDK4Header header;
    uint32_t gde_entries, gd_size;
    int64_t gd_offset, rgd_offset, capacity, gt_size;
    char p_desc[DESC_SIZE], s_desc[DESC_SIZE], hdr[HEADER_SIZE];
    char *desc_template =
    "# Disk DescriptorFile\n"
    "version=1\n"
    "CID=%x\n"
    "parentCID=%x\n"
    "createType=\"monolithicSparse\"\n"
    "parentFileNameHint=\"%s\"\n"
    "\n"
    "# Extent description\n"
    "RW %lu SPARSE \"%s\"\n"
    "\n"
    "# The Disk Data Base \n"
    "#DDB\n"
    "\n";

    snp_fd = open(filename, O_RDWR | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, 0644);
    if (snp_fd < 0)
        return -1;
    p_fd = open(backing_file, O_RDONLY | O_BINARY | O_LARGEFILE);
    if (p_fd < 0) {
        close(snp_fd);
        return -1;
    }

    /* read the header */
    if (lseek(p_fd, 0x0, SEEK_SET) == -1)
        goto fail;
    if (read(p_fd, hdr, HEADER_SIZE) != HEADER_SIZE)
        goto fail;

    /* write the header */
    if (lseek(snp_fd, 0x0, SEEK_SET) == -1)
        goto fail;
    if (write(snp_fd, hdr, HEADER_SIZE) == -1)
        goto fail;

    memset(&header, 0, sizeof(header));
    memcpy(&header,&hdr[4], sizeof(header)); // skip the VMDK4_MAGIC

    ftruncate(snp_fd, header.grain_offset << 9);
    /* the descriptor offset = 0x200 */
    if (lseek(p_fd, 0x200, SEEK_SET) == -1)
        goto fail;
    if (read(p_fd, p_desc, DESC_SIZE) != DESC_SIZE)
        goto fail;

    if ((p_name = strstr(p_desc,"CID")) != 0) {
        p_name += sizeof("CID");
        sscanf(p_name,"%x",&p_cid);
    }

    real_filename = filename;
    if ((temp_str = strrchr(real_filename, '\\')) != NULL)
        real_filename = temp_str + 1;
    if ((temp_str = strrchr(real_filename, '/')) != NULL)
        real_filename = temp_str + 1;
    if ((temp_str = strrchr(real_filename, ':')) != NULL)
        real_filename = temp_str + 1;

    sprintf(s_desc, desc_template, p_cid, p_cid, backing_file
            , (uint32_t)header.capacity, real_filename);

    /* write the descriptor */
    if (lseek(snp_fd, 0x200, SEEK_SET) == -1)
        goto fail;
    if (write(snp_fd, s_desc, strlen(s_desc)) == -1)
        goto fail;

    gd_offset = header.gd_offset * SECTOR_SIZE;     // offset of GD table
    rgd_offset = header.rgd_offset * SECTOR_SIZE;   // offset of RGD table
    capacity = header.capacity * SECTOR_SIZE;       // Extent size
    /*
     * Each GDE span 32M disk, means:
     * 512 GTE per GT, each GTE points to grain
     */
    gt_size = (int64_t)header.num_gtes_per_gte * header.granularity * SECTOR_SIZE;
    if (!gt_size)
        goto fail;
    gde_entries = (uint32_t)(capacity / gt_size);  // number of gde/rgde
    gd_size = gde_entries * sizeof(uint32_t);

    /* write RGD */
    rgd_buf = qemu_malloc(gd_size);
    if (!rgd_buf)
        goto fail;
    if (lseek(p_fd, rgd_offset, SEEK_SET) == -1)
        goto fail_rgd;
    if (read(p_fd, rgd_buf, gd_size) != gd_size)
        goto fail_rgd;
    if (lseek(snp_fd, rgd_offset, SEEK_SET) == -1)
        goto fail_rgd;
    if (write(snp_fd, rgd_buf, gd_size) == -1)
        goto fail_rgd;
    qemu_free(rgd_buf);

    /* write GD */
    gd_buf = qemu_malloc(gd_size);
    if (!gd_buf)
        goto fail_rgd;
    if (lseek(p_fd, gd_offset, SEEK_SET) == -1)
        goto fail_gd;
    if (read(p_fd, gd_buf, gd_size) != gd_size)
        goto fail_gd;
    if (lseek(snp_fd, gd_offset, SEEK_SET) == -1)
        goto fail_gd;
    if (write(snp_fd, gd_buf, gd_size) == -1)
        goto fail_gd;
    qemu_free(gd_buf);

    close(p_fd);
    close(snp_fd);
    return 0;

    fail_gd:
    qemu_free(gd_buf);
    fail_rgd:  
    qemu_free(rgd_buf);
    fail:
    close(p_fd);
    close(snp_fd);
    return -1;
}

static void vmdk_parent_close(BlockDriverState *bs)
{
    if (bs->backing_hd)
        bdrv_close(bs->backing_hd);
}

int parent_open = 0;
static int vmdk_parent_open(BlockDriverState *bs, const char * filename)
{
    BDRVVmdkState *s = bs->opaque;
    char *p_name;
    char desc[DESC_SIZE];
    char parent_img_name[1024];

    /* the descriptor offset = 0x200 */
    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)
        return -1;

    if ((p_name = strstr(desc,"parentFileNameHint")) != 0) {
        char *end_name;
        struct stat file_buf;

        p_name += sizeof("parentFileNameHint") + 1;
        if ((end_name = strchr(p_name,'\"')) == 0)
            return -1;
               
        strncpy(s->hd->backing_file, p_name, end_name - p_name);
        if (stat(s->hd->backing_file, &file_buf) != 0) {
            path_combine(parent_img_name, sizeof(parent_img_name),
                         filename, s->hd->backing_file);
        } else {
            strcpy(parent_img_name, s->hd->backing_file);
        }

        s->hd->backing_hd = bdrv_new("");
        if (!s->hd->backing_hd) {
            failure:
            bdrv_close(s->hd);
            return -1;
        }
        parent_open = 1;
        if (bdrv_open(s->hd->backing_hd, parent_img_name, BDRV_O_RDONLY) < 0)
            goto failure;
        parent_open = 0;
    }

    return 0;
}

static int vmdk_open(BlockDriverState *bs, const char *filename, int flags)
{
    BDRVVmdkState *s = bs->opaque;
    uint32_t magic;
    int l1_size, i, ret;

    if (parent_open)
        // Parent must be opened as RO.
        flags = BDRV_O_RDONLY;
    fprintf(stderr, "(VMDK) image open: flags=0x%x filename=%s\n", flags, bs->filename);

    ret = bdrv_file_open(&s->hd, filename, flags);
    if (ret < 0)
        return ret;
    if (bdrv_pread(s->hd, 0, &magic, sizeof(magic)) != sizeof(magic))
        goto fail;

    magic = be32_to_cpu(magic);
    if (magic == VMDK3_MAGIC) {
        VMDK3Header header;

        if (bdrv_pread(s->hd, sizeof(magic), &header, sizeof(header)) != sizeof(header))
            goto fail;
        s->cluster_sectors = le32_to_cpu(header.granularity);
        s->l2_size = 1 << 9;
        s->l1_size = 1 << 6;
        bs->total_sectors = le32_to_cpu(header.disk_sectors);
        s->l1_table_offset = le32_to_cpu(header.l1dir_offset) << 9;
        s->l1_backup_table_offset = 0;
        s->l1_entry_sectors = s->l2_size * s->cluster_sectors;
    } else if (magic == VMDK4_MAGIC) {
        VMDK4Header header;

        if (bdrv_pread(s->hd, sizeof(magic), &header, sizeof(header)) != sizeof(header))
            goto fail;
        bs->total_sectors = le64_to_cpu(header.capacity);
        s->cluster_sectors = le64_to_cpu(header.granularity);
        s->l2_size = le32_to_cpu(header.num_gtes_per_gte);
        s->l1_entry_sectors = s->l2_size * s->cluster_sectors;
        if (s->l1_entry_sectors <= 0)
            goto fail;
        s->l1_size = (bs->total_sectors + s->l1_entry_sectors - 1)
            / s->l1_entry_sectors;
        s->l1_table_offset = le64_to_cpu(header.rgd_offset) << 9;
        s->l1_backup_table_offset = le64_to_cpu(header.gd_offset) << 9;

        if (parent_open)
            s->is_parent = 1;
        else
            s->is_parent = 0;

        // try to open parent images, if exist
        if (vmdk_parent_open(bs, filename) != 0)
            goto fail;
        // write the CID once after the image creation
        s->parent_cid = vmdk_read_cid(bs,1);
    } else {
        goto fail;
    }

    /* read the L1 table */
    l1_size = s->l1_size * sizeof(uint32_t);
    s->l1_table = qemu_malloc(l1_size);
    if (!s->l1_table)
        goto fail;
    if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, l1_size) != l1_size)
        goto fail;
    for(i = 0; i < s->l1_size; i++) {
        le32_to_cpus(&s->l1_table[i]);
    }

    if (s->l1_backup_table_offset) {
        s->l1_backup_table = qemu_malloc(l1_size);
        if (!s->l1_backup_table)
            goto fail;
        if (bdrv_pread(s->hd, s->l1_backup_table_offset, s->l1_backup_table, l1_size) != l1_size)
            goto fail;
        for(i = 0; i < s->l1_size; i++) {
            le32_to_cpus(&s->l1_backup_table[i]);
        }
    }

    s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint32_t));
    if (!s->l2_cache)
        goto fail;
    return 0;
 fail:
    qemu_free(s->l1_backup_table);
    qemu_free(s->l1_table);
    qemu_free(s->l2_cache);
    bdrv_delete(s->hd);
    return -1;
}

static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,
                                   uint64_t offset, int allocate);

static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset,
                             uint64_t offset, int allocate)
{
    uint64_t parent_cluster_offset;
    BDRVVmdkState *s = bs->opaque;
    uint8_t  whole_grain[s->cluster_sectors*512];        // 128 sectors * 512 bytes each = grain size 64KB

    // we will be here if it's first write on non-exist grain(cluster).
    // try to read from parent image, if exist
    if (s->hd->backing_hd) {
        BDRVVmdkState *ps = s->hd->backing_hd->opaque;

        if (!vmdk_is_cid_valid(bs))
            return -1;

        parent_cluster_offset = get_cluster_offset(s->hd->backing_hd, NULL, offset, allocate);

        if (parent_cluster_offset) {
            BDRVVmdkState *act_s = activeBDRV.hd->opaque;

            if (bdrv_pread(ps->hd, parent_cluster_offset, whole_grain, ps->cluster_sectors*512) != ps->cluster_sectors*512)
                return -1;

            //Write grain only into the active image
            if (bdrv_pwrite(act_s->hd, activeBDRV.cluster_offset << 9, whole_grain, sizeof(whole_grain)) != sizeof(whole_grain))
                return -1;
        }
    }
    return 0;
}

static int vmdk_L2update(BlockDriverState *bs, VmdkMetaData *m_data)
{
    BDRVVmdkState *s = bs->opaque;

    /* update L2 table */
    if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),
                    &(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))
        return -1;
    /* update backup L2 table */
    if (s->l1_backup_table_offset != 0) {
        m_data->l2_offset = s->l1_backup_table[m_data->l1_index];
        if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),
                        &(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))
            return -1;
    }

    return 0;
}

static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,
                                   uint64_t offset, int allocate)
{
    BDRVVmdkState *s = bs->opaque;
    unsigned int l1_index, l2_offset, l2_index;
    int min_index, i, j;
    uint32_t min_count, *l2_table, tmp = 0;
    uint64_t cluster_offset;

    if (m_data)
        m_data->valid = 0;

    l1_index = (offset >> 9) / s->l1_entry_sectors;
    if (l1_index >= s->l1_size)
        return 0;
    l2_offset = s->l1_table[l1_index];
    if (!l2_offset)
        return 0;
    for(i = 0; i < L2_CACHE_SIZE; i++) {
        if (l2_offset == s->l2_cache_offsets[i]) {
            /* increment the hit count */
            if (++s->l2_cache_counts[i] == 0xffffffff) {
                for(j = 0; j < L2_CACHE_SIZE; j++) {
                    s->l2_cache_counts[j] >>= 1;
                }
            }
            l2_table = s->l2_cache + (i * s->l2_size);
            goto found;
        }
    }
    /* not found: load a new entry in the least used one */
    min_index = 0;
    min_count = 0xffffffff;
    for(i = 0; i < L2_CACHE_SIZE; i++) {
        if (s->l2_cache_counts[i] < min_count) {
            min_count = s->l2_cache_counts[i];
            min_index = i;
        }
    }
    l2_table = s->l2_cache + (min_index * s->l2_size);
    if (bdrv_pread(s->hd, (int64_t)l2_offset * 512, l2_table, s->l2_size * sizeof(uint32_t)) !=
                                                                        s->l2_size * sizeof(uint32_t))
        return 0;

    s->l2_cache_offsets[min_index] = l2_offset;
    s->l2_cache_counts[min_index] = 1;
 found:
    l2_index = ((offset >> 9) / s->cluster_sectors) % s->l2_size;
    cluster_offset = le32_to_cpu(l2_table[l2_index]);

    if (!cluster_offset) {
        if (!allocate)
            return 0;
        // Avoid the L2 tables update for the images that have snapshots.
        if (!s->is_parent) {
            cluster_offset = bdrv_getlength(s->hd);
            bdrv_truncate(s->hd, cluster_offset + (s->cluster_sectors << 9));

            cluster_offset >>= 9;
            tmp = cpu_to_le32(cluster_offset);
            l2_table[l2_index] = tmp;
            // Save the active image state
            activeBDRV.cluster_offset = cluster_offset;
            activeBDRV.hd = bs;
        }
        /* First of all we write grain itself, to avoid race condition
         * that may to corrupt the image.
         * This problem may occur because of insufficient space on host disk
         * or inappropriate VM shutdown.
         */
        if (get_whole_cluster(bs, cluster_offset, offset, allocate) == -1)
            return 0;

        if (m_data) {
            m_data->offset = tmp;
            m_data->l1_index = l1_index;
            m_data->l2_index = l2_index;
            m_data->l2_offset = l2_offset;
            m_data->valid = 1;
        }
    }
    cluster_offset <<= 9;
    return cluster_offset;
}

static int vmdk_is_allocated(BlockDriverState *bs, int64_t sector_num,
                             int nb_sectors, int *pnum)
{
    BDRVVmdkState *s = bs->opaque;
    int index_in_cluster, n;
    uint64_t cluster_offset;

    cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);
    index_in_cluster = sector_num % s->cluster_sectors;
    n = s->cluster_sectors - index_in_cluster;
    if (n > nb_sectors)
        n = nb_sectors;
    *pnum = n;
    return (cluster_offset != 0);
}

static int vmdk_read(BlockDriverState *bs, int64_t sector_num,
                    uint8_t *buf, int nb_sectors)
{
    BDRVVmdkState *s = bs->opaque;
    int index_in_cluster, n, ret;
    uint64_t cluster_offset;

    while (nb_sectors > 0) {
        cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);
        index_in_cluster = sector_num % s->cluster_sectors;
        n = s->cluster_sectors - index_in_cluster;
        if (n > nb_sectors)
            n = nb_sectors;
        if (!cluster_offset) {
            // try to read from parent image, if exist
            if (s->hd->backing_hd) {
                if (!vmdk_is_cid_valid(bs))
                    return -1;
                ret = bdrv_read(s->hd->backing_hd, sector_num, buf, n);
                if (ret < 0)
                    return -1;
            } else {
                memset(buf, 0, 512 * n);
            }
        } else {
            if(bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)
                return -1;
        }
        nb_sectors -= n;
        sector_num += n;
        buf += n * 512;
    }
    return 0;
}

static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
                     const uint8_t *buf, int nb_sectors)
{
    BDRVVmdkState *s = bs->opaque;
    VmdkMetaData m_data;
    int index_in_cluster, n;
    uint64_t cluster_offset;
    static int cid_update = 0;

    if (sector_num > bs->total_sectors) {
        fprintf(stderr,
                "(VMDK) Wrong offset: sector_num=0x%llx total_sectors=0x%llx\n",
                sector_num, bs->total_sectors);
        return -1;
    }

    while (nb_sectors > 0) {
        index_in_cluster = sector_num & (s->cluster_sectors - 1);
        n = s->cluster_sectors - index_in_cluster;
        if (n > nb_sectors)
            n = nb_sectors;
        cluster_offset = get_cluster_offset(bs, &m_data, sector_num << 9, 1);
        if (!cluster_offset)
            return -1;

        if (bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)
            return -1;
        if (m_data.valid) {
            /* update L2 tables */
            if (vmdk_L2update(bs, &m_data) == -1)
                return -1;
        }
        nb_sectors -= n;
        sector_num += n;
        buf += n * 512;

        // update CID on the first write every time the virtual disk is opened
        if (!cid_update) {
            vmdk_write_cid(bs, time(NULL));
            cid_update++;
        }
    }
    return 0;
}

static int vmdk_create(const char *filename, int64_t total_size,
                       const char *backing_file, int flags)
{
    int fd, i;
    VMDK4Header header;
    uint32_t tmp, magic, grains, gd_size, gt_size, gt_count;
    char *desc_template =
        "# Disk DescriptorFile\n"
        "version=1\n"
        "CID=%x\n"
        "parentCID=ffffffff\n"
        "createType=\"monolithicSparse\"\n"
        "\n"
        "# Extent description\n"
        "RW %lu SPARSE \"%s\"\n"
        "\n"
        "# The Disk Data Base \n"
        "#DDB\n"
        "\n"
        "ddb.virtualHWVersion = \"4\"\n"
        "ddb.geometry.cylinders = \"%lu\"\n"
        "ddb.geometry.heads = \"16\"\n"
        "ddb.geometry.sectors = \"63\"\n"
        "ddb.adapterType = \"ide\"\n";
    char desc[1024];
    const char *real_filename, *temp_str;

    /* XXX: add support for backing file */
    if (backing_file) {
        return vmdk_snapshot_create(filename, backing_file);
    }

    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
              0644);
    if (fd < 0)
        return -1;
    magic = cpu_to_be32(VMDK4_MAGIC);
    memset(&header, 0, sizeof(header));
    header.version = cpu_to_le32(1);
    header.flags = cpu_to_le32(3); /* ?? */
    header.capacity = cpu_to_le64(total_size);
    header.granularity = cpu_to_le64(128);
    header.num_gtes_per_gte = cpu_to_le32(512);

    grains = (total_size + header.granularity - 1) / header.granularity;
    gt_size = ((header.num_gtes_per_gte * sizeof(uint32_t)) + 511) >> 9;
    gt_count = (grains + header.num_gtes_per_gte - 1) / header.num_gtes_per_gte;
    gd_size = (gt_count * sizeof(uint32_t) + 511) >> 9;

    header.desc_offset = 1;
    header.desc_size = 20;
    header.rgd_offset = header.desc_offset + header.desc_size;
    header.gd_offset = header.rgd_offset + gd_size + (gt_size * gt_count);
    header.grain_offset =
       ((header.gd_offset + gd_size + (gt_size * gt_count) +
         header.granularity - 1) / header.granularity) *
        header.granularity;

    header.desc_offset = cpu_to_le64(header.desc_offset);
    header.desc_size = cpu_to_le64(header.desc_size);
    header.rgd_offset = cpu_to_le64(header.rgd_offset);
    header.gd_offset = cpu_to_le64(header.gd_offset);
    header.grain_offset = cpu_to_le64(header.grain_offset);

    header.check_bytes[0] = 0xa;
    header.check_bytes[1] = 0x20;
    header.check_bytes[2] = 0xd;
    header.check_bytes[3] = 0xa;
   
    /* write all the data */   
    write(fd, &magic, sizeof(magic));
    write(fd, &header, sizeof(header));

    ftruncate(fd, header.grain_offset << 9);

    /* write grain directory */
    lseek(fd, le64_to_cpu(header.rgd_offset) << 9, SEEK_SET);
    for (i = 0, tmp = header.rgd_offset + gd_size;
         i < gt_count; i++, tmp += gt_size)
        write(fd, &tmp, sizeof(tmp));
  
    /* write backup grain directory */
    lseek(fd, le64_to_cpu(header.gd_offset) << 9, SEEK_SET);
    for (i = 0, tmp = header.gd_offset + gd_size;
         i < gt_count; i++, tmp += gt_size)
        write(fd, &tmp, sizeof(tmp));

    /* compose the descriptor */
    real_filename = filename;
    if ((temp_str = strrchr(real_filename, '\\')) != NULL)
        real_filename = temp_str + 1;
    if ((temp_str = strrchr(real_filename, '/')) != NULL)
        real_filename = temp_str + 1;
    if ((temp_str = strrchr(real_filename, ':')) != NULL)
        real_filename = temp_str + 1;
    sprintf(desc, desc_template, time(NULL), (unsigned long)total_size,
            real_filename, total_size / (63 * 16));

    /* write the descriptor */
    lseek(fd, le64_to_cpu(header.desc_offset) << 9, SEEK_SET);
    write(fd, desc, strlen(desc));

    close(fd);
    return 0;
}

static void vmdk_close(BlockDriverState *bs)
{
    BDRVVmdkState *s = bs->opaque;

    qemu_free(s->l1_table);
    qemu_free(s->l2_cache);
    bdrv_delete(s->hd);
    // try to close parent image, if exist
    vmdk_parent_close(s->hd);
}

static void vmdk_flush(BlockDriverState *bs)
{
    BDRVVmdkState *s = bs->opaque;
    bdrv_flush(s->hd);
}

BlockDriver bdrv_vmdk = {
    "vmdk",
    sizeof(BDRVVmdkState),
    vmdk_probe,
    vmdk_open,
    vmdk_read,
    vmdk_write,
    vmdk_close,
    vmdk_create,
    vmdk_flush,
    vmdk_is_allocated,
};