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1
/*
2
 * Block driver for Conectix/Microsoft Virtual PC images
3
 *
4
 * Copyright (c) 2005 Alex Beregszaszi
5
 * Copyright (c) 2009 Kevin Wolf <kwolf@suse.de>
6
 *
7
 * Permission is hereby granted, free of charge, to any person obtaining a copy
8
 * of this software and associated documentation files (the "Software"), to deal
9
 * in the Software without restriction, including without limitation the rights
10
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11
 * copies of the Software, and to permit persons to whom the Software is
12
 * furnished to do so, subject to the following conditions:
13
 *
14
 * The above copyright notice and this permission notice shall be included in
15
 * all copies or substantial portions of the Software.
16
 *
17
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23
 * THE SOFTWARE.
24
 */
25
#include "qemu-common.h"
26
#include "block_int.h"
27

    
28
/**************************************************************/
29

    
30
#define HEADER_SIZE 512
31

    
32
//#define CACHE
33

    
34
enum vhd_type {
35
    VHD_FIXED           = 2,
36
    VHD_DYNAMIC         = 3,
37
    VHD_DIFFERENCING    = 4,
38
};
39

    
40
// Seconds since Jan 1, 2000 0:00:00 (UTC)
41
#define VHD_TIMESTAMP_BASE 946684800
42

    
43
// always big-endian
44
struct vhd_footer {
45
    char        creator[8]; // "conectix"
46
    uint32_t    features;
47
    uint32_t    version;
48

    
49
    // Offset of next header structure, 0xFFFFFFFF if none
50
    uint64_t    data_offset;
51

    
52
    // Seconds since Jan 1, 2000 0:00:00 (UTC)
53
    uint32_t    timestamp;
54

    
55
    char        creator_app[4]; // "vpc "
56
    uint16_t    major;
57
    uint16_t    minor;
58
    char        creator_os[4]; // "Wi2k"
59

    
60
    uint64_t    orig_size;
61
    uint64_t    size;
62

    
63
    uint16_t    cyls;
64
    uint8_t     heads;
65
    uint8_t     secs_per_cyl;
66

    
67
    uint32_t    type;
68

    
69
    // Checksum of the Hard Disk Footer ("one's complement of the sum of all
70
    // the bytes in the footer without the checksum field")
71
    uint32_t    checksum;
72

    
73
    // UUID used to identify a parent hard disk (backing file)
74
    uint8_t     uuid[16];
75

    
76
    uint8_t     in_saved_state;
77
};
78

    
79
struct vhd_dyndisk_header {
80
    char        magic[8]; // "cxsparse"
81

    
82
    // Offset of next header structure, 0xFFFFFFFF if none
83
    uint64_t    data_offset;
84

    
85
    // Offset of the Block Allocation Table (BAT)
86
    uint64_t    table_offset;
87

    
88
    uint32_t    version;
89
    uint32_t    max_table_entries; // 32bit/entry
90

    
91
    // 2 MB by default, must be a power of two
92
    uint32_t    block_size;
93

    
94
    uint32_t    checksum;
95
    uint8_t     parent_uuid[16];
96
    uint32_t    parent_timestamp;
97
    uint32_t    reserved;
98

    
99
    // Backing file name (in UTF-16)
100
    uint8_t     parent_name[512];
101

    
102
    struct {
103
        uint32_t    platform;
104
        uint32_t    data_space;
105
        uint32_t    data_length;
106
        uint32_t    reserved;
107
        uint64_t    data_offset;
108
    } parent_locator[8];
109
};
110

    
111
typedef struct BDRVVPCState {
112
    BlockDriverState *hd;
113

    
114
    uint8_t footer_buf[HEADER_SIZE];
115
    uint64_t free_data_block_offset;
116
    int max_table_entries;
117
    uint32_t *pagetable;
118
    uint64_t bat_offset;
119
    uint64_t last_bitmap_offset;
120

    
121
    uint32_t block_size;
122
    uint32_t bitmap_size;
123

    
124
#ifdef CACHE
125
    uint8_t *pageentry_u8;
126
    uint32_t *pageentry_u32;
127
    uint16_t *pageentry_u16;
128

    
129
    uint64_t last_bitmap;
130
#endif
131
} BDRVVPCState;
132

    
133
static uint32_t vpc_checksum(uint8_t* buf, size_t size)
134
{
135
    uint32_t res = 0;
136
    int i;
137

    
138
    for (i = 0; i < size; i++)
139
        res += buf[i];
140

    
141
    return ~res;
142
}
143

    
144

    
145
static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
146
{
147
    if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
148
        return 100;
149
    return 0;
150
}
151

    
152
static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
153
{
154
    BDRVVPCState *s = bs->opaque;
155
    int ret, i;
156
    struct vhd_footer* footer;
157
    struct vhd_dyndisk_header* dyndisk_header;
158
    uint8_t buf[HEADER_SIZE];
159
    uint32_t checksum;
160

    
161
    ret = bdrv_file_open(&s->hd, filename, flags);
162
    if (ret < 0)
163
        return ret;
164

    
165
    if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
166
        goto fail;
167

    
168
    footer = (struct vhd_footer*) s->footer_buf;
169
    if (strncmp(footer->creator, "conectix", 8))
170
        goto fail;
171

    
172
    checksum = be32_to_cpu(footer->checksum);
173
    footer->checksum = 0;
174
    if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
175
        fprintf(stderr, "block-vpc: The header checksum of '%s' is "
176
            "incorrect.\n", filename);
177

    
178
    // The visible size of a image in Virtual PC depends on the geometry
179
    // rather than on the size stored in the footer (the size in the footer
180
    // is too large usually)
181
    bs->total_sectors = (int64_t)
182
        be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
183

    
184
    if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
185
            != HEADER_SIZE)
186
        goto fail;
187

    
188
    dyndisk_header = (struct vhd_dyndisk_header*) buf;
189

    
190
    if (strncmp(dyndisk_header->magic, "cxsparse", 8))
191
        goto fail;
192

    
193

    
194
    s->block_size = be32_to_cpu(dyndisk_header->block_size);
195
    s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
196

    
197
    s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
198
    s->pagetable = qemu_malloc(s->max_table_entries * 4);
199

    
200
    s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
201
    if (bdrv_pread(s->hd, s->bat_offset, s->pagetable,
202
            s->max_table_entries * 4) != s->max_table_entries * 4)
203
            goto fail;
204

    
205
    s->free_data_block_offset =
206
        (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
207

    
208
    for (i = 0; i < s->max_table_entries; i++) {
209
        be32_to_cpus(&s->pagetable[i]);
210
        if (s->pagetable[i] != 0xFFFFFFFF) {
211
            int64_t next = (512 * (int64_t) s->pagetable[i]) +
212
                s->bitmap_size + s->block_size;
213

    
214
            if (next> s->free_data_block_offset)
215
                s->free_data_block_offset = next;
216
        }
217
    }
218

    
219
    s->last_bitmap_offset = (int64_t) -1;
220

    
221
#ifdef CACHE
222
    s->pageentry_u8 = qemu_malloc(512);
223
    s->pageentry_u32 = s->pageentry_u8;
224
    s->pageentry_u16 = s->pageentry_u8;
225
    s->last_pagetable = -1;
226
#endif
227

    
228
    return 0;
229
 fail:
230
    bdrv_delete(s->hd);
231
    return -1;
232
}
233

    
234
/*
235
 * Returns the absolute byte offset of the given sector in the image file.
236
 * If the sector is not allocated, -1 is returned instead.
237
 *
238
 * The parameter write must be 1 if the offset will be used for a write
239
 * operation (the block bitmaps is updated then), 0 otherwise.
240
 */
241
static inline int64_t get_sector_offset(BlockDriverState *bs,
242
    int64_t sector_num, int write)
243
{
244
    BDRVVPCState *s = bs->opaque;
245
    uint64_t offset = sector_num * 512;
246
    uint64_t bitmap_offset, block_offset;
247
    uint32_t pagetable_index, pageentry_index;
248

    
249
    pagetable_index = offset / s->block_size;
250
    pageentry_index = (offset % s->block_size) / 512;
251

    
252
    if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
253
        return -1; // not allocated
254

    
255
    bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
256
    block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
257

    
258
    // We must ensure that we don't write to any sectors which are marked as
259
    // unused in the bitmap. We get away with setting all bits in the block
260
    // bitmap each time we write to a new block. This might cause Virtual PC to
261
    // miss sparse read optimization, but it's not a problem in terms of
262
    // correctness.
263
    if (write && (s->last_bitmap_offset != bitmap_offset)) {
264
        uint8_t bitmap[s->bitmap_size];
265

    
266
        s->last_bitmap_offset = bitmap_offset;
267
        memset(bitmap, 0xff, s->bitmap_size);
268
        bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size);
269
    }
270

    
271
//    printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
272
//        sector_num, pagetable_index, pageentry_index,
273
//        bitmap_offset, block_offset);
274

    
275
// disabled by reason
276
#if 0
277
#ifdef CACHE
278
    if (bitmap_offset != s->last_bitmap)
279
    {
280
        lseek(s->fd, bitmap_offset, SEEK_SET);
281

282
        s->last_bitmap = bitmap_offset;
283

284
        // Scary! Bitmap is stored as big endian 32bit entries,
285
        // while we used to look it up byte by byte
286
        read(s->fd, s->pageentry_u8, 512);
287
        for (i = 0; i < 128; i++)
288
            be32_to_cpus(&s->pageentry_u32[i]);
289
    }
290

291
    if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
292
        return -1;
293
#else
294
    lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
295

    
296
    read(s->fd, &bitmap_entry, 1);
297

    
298
    if ((bitmap_entry >> (pageentry_index % 8)) & 1)
299
        return -1; // not allocated
300
#endif
301
#endif
302

    
303
    return block_offset;
304
}
305

    
306
/*
307
 * Writes the footer to the end of the image file. This is needed when the
308
 * file grows as it overwrites the old footer
309
 *
310
 * Returns 0 on success and < 0 on error
311
 */
312
static int rewrite_footer(BlockDriverState* bs)
313
{
314
    int ret;
315
    BDRVVPCState *s = bs->opaque;
316
    int64_t offset = s->free_data_block_offset;
317

    
318
    ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE);
319
    if (ret < 0)
320
        return ret;
321

    
322
    return 0;
323
}
324

    
325
/*
326
 * Allocates a new block. This involves writing a new footer and updating
327
 * the Block Allocation Table to use the space at the old end of the image
328
 * file (overwriting the old footer)
329
 *
330
 * Returns the sectors' offset in the image file on success and < 0 on error
331
 */
332
static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
333
{
334
    BDRVVPCState *s = bs->opaque;
335
    int64_t bat_offset;
336
    uint32_t index, bat_value;
337
    int ret;
338
    uint8_t bitmap[s->bitmap_size];
339

    
340
    // Check if sector_num is valid
341
    if ((sector_num < 0) || (sector_num > bs->total_sectors))
342
        return -1;
343

    
344
    // Write entry into in-memory BAT
345
    index = (sector_num * 512) / s->block_size;
346
    if (s->pagetable[index] != 0xFFFFFFFF)
347
        return -1;
348

    
349
    s->pagetable[index] = s->free_data_block_offset / 512;
350

    
351
    // Initialize the block's bitmap
352
    memset(bitmap, 0xff, s->bitmap_size);
353
    bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size);
354

    
355
    // Write new footer (the old one will be overwritten)
356
    s->free_data_block_offset += s->block_size + s->bitmap_size;
357
    ret = rewrite_footer(bs);
358
    if (ret < 0)
359
        goto fail;
360

    
361
    // Write BAT entry to disk
362
    bat_offset = s->bat_offset + (4 * index);
363
    bat_value = be32_to_cpu(s->pagetable[index]);
364
    ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4);
365
    if (ret < 0)
366
        goto fail;
367

    
368
    return get_sector_offset(bs, sector_num, 0);
369

    
370
fail:
371
    s->free_data_block_offset -= (s->block_size + s->bitmap_size);
372
    return -1;
373
}
374

    
375
static int vpc_read(BlockDriverState *bs, int64_t sector_num,
376
                    uint8_t *buf, int nb_sectors)
377
{
378
    BDRVVPCState *s = bs->opaque;
379
    int ret;
380
    int64_t offset;
381

    
382
    while (nb_sectors > 0) {
383
        offset = get_sector_offset(bs, sector_num, 0);
384

    
385
        if (offset == -1) {
386
            memset(buf, 0, 512);
387
        } else {
388
            ret = bdrv_pread(s->hd, offset, buf, 512);
389
            if (ret != 512)
390
                return -1;
391
        }
392

    
393
        nb_sectors--;
394
        sector_num++;
395
        buf += 512;
396
    }
397
    return 0;
398
}
399

    
400
static int vpc_write(BlockDriverState *bs, int64_t sector_num,
401
    const uint8_t *buf, int nb_sectors)
402
{
403
    BDRVVPCState *s = bs->opaque;
404
    int64_t offset;
405
    int ret;
406

    
407
    while (nb_sectors > 0) {
408
        offset = get_sector_offset(bs, sector_num, 1);
409

    
410
        if (offset == -1) {
411
            offset = alloc_block(bs, sector_num);
412
            if (offset < 0)
413
                return -1;
414
        }
415

    
416
        ret = bdrv_pwrite(s->hd, offset, buf, 512);
417
        if (ret != 512)
418
            return -1;
419

    
420
        nb_sectors--;
421
        sector_num++;
422
        buf += 512;
423
    }
424

    
425
    return 0;
426
}
427

    
428

    
429
/*
430
 * Calculates the number of cylinders, heads and sectors per cylinder
431
 * based on a given number of sectors. This is the algorithm described
432
 * in the VHD specification.
433
 *
434
 * Note that the geometry doesn't always exactly match total_sectors but
435
 * may round it down.
436
 *
437
 * Returns 0 on success, -EFBIG if the size is larger than 127 GB
438
 */
439
static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
440
    uint8_t* heads, uint8_t* secs_per_cyl)
441
{
442
    uint32_t cyls_times_heads;
443

    
444
    if (total_sectors > 65535 * 16 * 255)
445
        return -EFBIG;
446

    
447
    if (total_sectors > 65535 * 16 * 63) {
448
        *secs_per_cyl = 255;
449
        *heads = 16;
450
        cyls_times_heads = total_sectors / *secs_per_cyl;
451
    } else {
452
        *secs_per_cyl = 17;
453
        cyls_times_heads = total_sectors / *secs_per_cyl;
454
        *heads = (cyls_times_heads + 1023) / 1024;
455

    
456
        if (*heads < 4)
457
            *heads = 4;
458

    
459
        if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
460
            *secs_per_cyl = 31;
461
            *heads = 16;
462
            cyls_times_heads = total_sectors / *secs_per_cyl;
463
        }
464

    
465
        if (cyls_times_heads >= (*heads * 1024)) {
466
            *secs_per_cyl = 63;
467
            *heads = 16;
468
            cyls_times_heads = total_sectors / *secs_per_cyl;
469
        }
470
    }
471

    
472
    // Note: Rounding up deviates from the Virtual PC behaviour
473
    // However, we need this to avoid truncating images in qemu-img convert
474
    *cyls = (cyls_times_heads + *heads - 1) / *heads;
475

    
476
    return 0;
477
}
478

    
479
static int vpc_create(const char *filename, int64_t total_sectors,
480
    const char *backing_file, int flags)
481
{
482
    uint8_t buf[1024];
483
    struct vhd_footer* footer = (struct vhd_footer*) buf;
484
    struct vhd_dyndisk_header* dyndisk_header =
485
        (struct vhd_dyndisk_header*) buf;
486
    int fd, i;
487
    uint16_t cyls;
488
    uint8_t heads;
489
    uint8_t secs_per_cyl;
490
    size_t block_size, num_bat_entries;
491

    
492
    if (backing_file != NULL)
493
        return -ENOTSUP;
494

    
495
    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
496
    if (fd < 0)
497
        return -EIO;
498

    
499
    // Calculate matching total_size and geometry
500
    if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl))
501
        return -EFBIG;
502
    total_sectors = (int64_t) cyls * heads * secs_per_cyl;
503

    
504
    // Prepare the Hard Disk Footer
505
    memset(buf, 0, 1024);
506

    
507
    strncpy(footer->creator, "conectix", 8);
508
    // TODO Check if "qemu" creator_app is ok for VPC
509
    strncpy(footer->creator_app, "qemu", 4);
510
    strncpy(footer->creator_os, "Wi2k", 4);
511

    
512
    footer->features = be32_to_cpu(0x02);
513
    footer->version = be32_to_cpu(0x00010000);
514
    footer->data_offset = be64_to_cpu(HEADER_SIZE);
515
    footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
516

    
517
    // Version of Virtual PC 2007
518
    footer->major = be16_to_cpu(0x0005);
519
    footer->minor =be16_to_cpu(0x0003);
520

    
521
    footer->orig_size = be64_to_cpu(total_sectors * 512);
522
    footer->size = be64_to_cpu(total_sectors * 512);
523

    
524
    footer->cyls = be16_to_cpu(cyls);
525
    footer->heads = heads;
526
    footer->secs_per_cyl = secs_per_cyl;
527

    
528
    footer->type = be32_to_cpu(VHD_DYNAMIC);
529

    
530
    // TODO uuid is missing
531

    
532
    footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
533

    
534
    // Write the footer (twice: at the beginning and at the end)
535
    block_size = 0x200000;
536
    num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
537

    
538
    if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
539
        return -EIO;
540

    
541
    if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
542
        return -EIO;
543
    if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
544
        return -EIO;
545

    
546
    // Write the initial BAT
547
    if (lseek(fd, 3 * 512, SEEK_SET) < 0)
548
        return -EIO;
549

    
550
    memset(buf, 0xFF, 512);
551
    for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
552
        if (write(fd, buf, 512) != 512)
553
            return -EIO;
554

    
555

    
556
    // Prepare the Dynamic Disk Header
557
    memset(buf, 0, 1024);
558

    
559
    strncpy(dyndisk_header->magic, "cxsparse", 8);
560

    
561
    dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
562
    dyndisk_header->table_offset = be64_to_cpu(3 * 512);
563
    dyndisk_header->version = be32_to_cpu(0x00010000);
564
    dyndisk_header->block_size = be32_to_cpu(block_size);
565
    dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
566

    
567
    dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
568

    
569
    // Write the header
570
    if (lseek(fd, 512, SEEK_SET) < 0)
571
        return -EIO;
572
    if (write(fd, buf, 1024) != 1024)
573
        return -EIO;
574

    
575
    close(fd);
576
    return 0;
577
}
578

    
579
static void vpc_close(BlockDriverState *bs)
580
{
581
    BDRVVPCState *s = bs->opaque;
582
    qemu_free(s->pagetable);
583
#ifdef CACHE
584
    qemu_free(s->pageentry_u8);
585
#endif
586
    bdrv_delete(s->hd);
587
}
588

    
589
BlockDriver bdrv_vpc = {
590
    .format_name        = "vpc",
591
    .instance_size        = sizeof(BDRVVPCState),
592
    .bdrv_probe                = vpc_probe,
593
    .bdrv_open                = vpc_open,
594
    .bdrv_read                = vpc_read,
595
    .bdrv_write                = vpc_write,
596
    .bdrv_close                = vpc_close,
597
    .bdrv_create        = vpc_create,
598
};