1 /*
2 * Block driver for Connectix / 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 #include "module.h"
28
29 /**************************************************************/
30
31 #define HEADER_SIZE 512
32
33 //#define CACHE
34
35 enum vhd_type {
36 VHD_FIXED = 2,
37 VHD_DYNAMIC = 3,
38 VHD_DIFFERENCING = 4,
39 };
40
41 // Seconds since Jan 1, 2000 0:00:00 (UTC)
42 #define VHD_TIMESTAMP_BASE 946684800
43
44 // always big-endian
45 struct vhd_footer {
46 char creator[8]; // "conectix"
47 uint32_t features;
48 uint32_t version;
49
50 // Offset of next header structure, 0xFFFFFFFF if none
51 uint64_t data_offset;
52
53 // Seconds since Jan 1, 2000 0:00:00 (UTC)
54 uint32_t timestamp;
55
56 char creator_app[4]; // "vpc "
57 uint16_t major;
58 uint16_t minor;
59 char creator_os[4]; // "Wi2k"
60
61 uint64_t orig_size;
62 uint64_t size;
63
64 uint16_t cyls;
65 uint8_t heads;
66 uint8_t secs_per_cyl;
67
68 uint32_t type;
69
70 // Checksum of the Hard Disk Footer ("one's complement of the sum of all
71 // the bytes in the footer without the checksum field")
72 uint32_t checksum;
73
74 // UUID used to identify a parent hard disk (backing file)
75 uint8_t uuid[16];
76
77 uint8_t in_saved_state;
78 };
79
80 struct vhd_dyndisk_header {
81 char magic[8]; // "cxsparse"
82
83 // Offset of next header structure, 0xFFFFFFFF if none
84 uint64_t data_offset;
85
86 // Offset of the Block Allocation Table (BAT)
87 uint64_t table_offset;
88
89 uint32_t version;
90 uint32_t max_table_entries; // 32bit/entry
91
92 // 2 MB by default, must be a power of two
93 uint32_t block_size;
94
95 uint32_t checksum;
96 uint8_t parent_uuid[16];
97 uint32_t parent_timestamp;
98 uint32_t reserved;
99
100 // Backing file name (in UTF-16)
101 uint8_t parent_name[512];
102
103 struct {
104 uint32_t platform;
105 uint32_t data_space;
106 uint32_t data_length;
107 uint32_t reserved;
108 uint64_t data_offset;
109 } parent_locator[8];
110 };
111
112 typedef struct BDRVVPCState {
113 BlockDriverState *hd;
114
115 uint8_t footer_buf[HEADER_SIZE];
116 uint64_t free_data_block_offset;
117 int max_table_entries;
118 uint32_t *pagetable;
119 uint64_t bat_offset;
120 uint64_t last_bitmap_offset;
121
122 uint32_t block_size;
123 uint32_t bitmap_size;
124
125 #ifdef CACHE
126 uint8_t *pageentry_u8;
127 uint32_t *pageentry_u32;
128 uint16_t *pageentry_u16;
129
130 uint64_t last_bitmap;
131 #endif
132 } BDRVVPCState;
133
vpc_checksum(uint8_t * buf,size_t size)134 static uint32_t vpc_checksum(uint8_t* buf, size_t size)
135 {
136 uint32_t res = 0;
137 int i;
138
139 for (i = 0; i < size; i++)
140 res += buf[i];
141
142 return ~res;
143 }
144
145
vpc_probe(const uint8_t * buf,int buf_size,const char * filename)146 static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
147 {
148 if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
149 return 100;
150 return 0;
151 }
152
vpc_open(BlockDriverState * bs,int flags)153 static int vpc_open(BlockDriverState *bs, int flags)
154 {
155 BDRVVPCState *s = bs->opaque;
156 int i;
157 struct vhd_footer* footer;
158 struct vhd_dyndisk_header* dyndisk_header;
159 uint8_t buf[HEADER_SIZE];
160 uint32_t checksum;
161
162 if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
163 goto fail;
164
165 footer = (struct vhd_footer*) s->footer_buf;
166 if (strncmp(footer->creator, "conectix", 8))
167 goto fail;
168
169 checksum = be32_to_cpu(footer->checksum);
170 footer->checksum = 0;
171 if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
172 fprintf(stderr, "block-vpc: The header checksum of '%s' is "
173 "incorrect.\n", bs->filename);
174
175 // The visible size of a image in Virtual PC depends on the geometry
176 // rather than on the size stored in the footer (the size in the footer
177 // is too large usually)
178 bs->total_sectors = (int64_t)
179 be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
180
181 if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
182 != HEADER_SIZE)
183 goto fail;
184
185 dyndisk_header = (struct vhd_dyndisk_header*) buf;
186
187 if (strncmp(dyndisk_header->magic, "cxsparse", 8))
188 goto fail;
189
190
191 s->block_size = be32_to_cpu(dyndisk_header->block_size);
192 s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
193
194 s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
195 s->pagetable = qemu_malloc(s->max_table_entries * 4);
196
197 s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
198 if (bdrv_pread(bs->file, s->bat_offset, s->pagetable,
199 s->max_table_entries * 4) != s->max_table_entries * 4)
200 goto fail;
201
202 s->free_data_block_offset =
203 (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
204
205 for (i = 0; i < s->max_table_entries; i++) {
206 be32_to_cpus(&s->pagetable[i]);
207 if (s->pagetable[i] != 0xFFFFFFFF) {
208 int64_t next = (512 * (int64_t) s->pagetable[i]) +
209 s->bitmap_size + s->block_size;
210
211 if (next> s->free_data_block_offset)
212 s->free_data_block_offset = next;
213 }
214 }
215
216 s->last_bitmap_offset = (int64_t) -1;
217
218 #ifdef CACHE
219 s->pageentry_u8 = qemu_malloc(512);
220 s->pageentry_u32 = s->pageentry_u8;
221 s->pageentry_u16 = s->pageentry_u8;
222 s->last_pagetable = -1;
223 #endif
224
225 return 0;
226 fail:
227 return -1;
228 }
229
230 /*
231 * Returns the absolute byte offset of the given sector in the image file.
232 * If the sector is not allocated, -1 is returned instead.
233 *
234 * The parameter write must be 1 if the offset will be used for a write
235 * operation (the block bitmaps is updated then), 0 otherwise.
236 */
get_sector_offset(BlockDriverState * bs,int64_t sector_num,int write)237 static inline int64_t get_sector_offset(BlockDriverState *bs,
238 int64_t sector_num, int write)
239 {
240 BDRVVPCState *s = bs->opaque;
241 uint64_t offset = sector_num * 512;
242 uint64_t bitmap_offset, block_offset;
243 uint32_t pagetable_index, pageentry_index;
244
245 pagetable_index = offset / s->block_size;
246 pageentry_index = (offset % s->block_size) / 512;
247
248 if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
249 return -1; // not allocated
250
251 bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
252 block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
253
254 // We must ensure that we don't write to any sectors which are marked as
255 // unused in the bitmap. We get away with setting all bits in the block
256 // bitmap each time we write to a new block. This might cause Virtual PC to
257 // miss sparse read optimization, but it's not a problem in terms of
258 // correctness.
259 if (write && (s->last_bitmap_offset != bitmap_offset)) {
260 uint8_t bitmap[s->bitmap_size];
261
262 s->last_bitmap_offset = bitmap_offset;
263 memset(bitmap, 0xff, s->bitmap_size);
264 bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
265 }
266
267 // printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
268 // sector_num, pagetable_index, pageentry_index,
269 // bitmap_offset, block_offset);
270
271 // disabled by reason
272 #if 0
273 #ifdef CACHE
274 if (bitmap_offset != s->last_bitmap)
275 {
276 lseek(s->fd, bitmap_offset, SEEK_SET);
277
278 s->last_bitmap = bitmap_offset;
279
280 // Scary! Bitmap is stored as big endian 32bit entries,
281 // while we used to look it up byte by byte
282 read(s->fd, s->pageentry_u8, 512);
283 for (i = 0; i < 128; i++)
284 be32_to_cpus(&s->pageentry_u32[i]);
285 }
286
287 if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
288 return -1;
289 #else
290 lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
291
292 read(s->fd, &bitmap_entry, 1);
293
294 if ((bitmap_entry >> (pageentry_index % 8)) & 1)
295 return -1; // not allocated
296 #endif
297 #endif
298
299 return block_offset;
300 }
301
302 /*
303 * Writes the footer to the end of the image file. This is needed when the
304 * file grows as it overwrites the old footer
305 *
306 * Returns 0 on success and < 0 on error
307 */
rewrite_footer(BlockDriverState * bs)308 static int rewrite_footer(BlockDriverState* bs)
309 {
310 int ret;
311 BDRVVPCState *s = bs->opaque;
312 int64_t offset = s->free_data_block_offset;
313
314 ret = bdrv_pwrite_sync(bs->file, offset, s->footer_buf, HEADER_SIZE);
315 if (ret < 0)
316 return ret;
317
318 return 0;
319 }
320
321 /*
322 * Allocates a new block. This involves writing a new footer and updating
323 * the Block Allocation Table to use the space at the old end of the image
324 * file (overwriting the old footer)
325 *
326 * Returns the sectors' offset in the image file on success and < 0 on error
327 */
alloc_block(BlockDriverState * bs,int64_t sector_num)328 static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
329 {
330 BDRVVPCState *s = bs->opaque;
331 int64_t bat_offset;
332 uint32_t index, bat_value;
333 int ret;
334 uint8_t bitmap[s->bitmap_size];
335
336 // Check if sector_num is valid
337 if ((sector_num < 0) || (sector_num > bs->total_sectors))
338 return -1;
339
340 // Write entry into in-memory BAT
341 index = (sector_num * 512) / s->block_size;
342 if (s->pagetable[index] != 0xFFFFFFFF)
343 return -1;
344
345 s->pagetable[index] = s->free_data_block_offset / 512;
346
347 // Initialize the block's bitmap
348 memset(bitmap, 0xff, s->bitmap_size);
349 bdrv_pwrite_sync(bs->file, s->free_data_block_offset, bitmap,
350 s->bitmap_size);
351
352 // Write new footer (the old one will be overwritten)
353 s->free_data_block_offset += s->block_size + s->bitmap_size;
354 ret = rewrite_footer(bs);
355 if (ret < 0)
356 goto fail;
357
358 // Write BAT entry to disk
359 bat_offset = s->bat_offset + (4 * index);
360 bat_value = be32_to_cpu(s->pagetable[index]);
361 ret = bdrv_pwrite_sync(bs->file, bat_offset, &bat_value, 4);
362 if (ret < 0)
363 goto fail;
364
365 return get_sector_offset(bs, sector_num, 0);
366
367 fail:
368 s->free_data_block_offset -= (s->block_size + s->bitmap_size);
369 return -1;
370 }
371
vpc_read(BlockDriverState * bs,int64_t sector_num,uint8_t * buf,int nb_sectors)372 static int vpc_read(BlockDriverState *bs, int64_t sector_num,
373 uint8_t *buf, int nb_sectors)
374 {
375 BDRVVPCState *s = bs->opaque;
376 int ret;
377 int64_t offset;
378 int64_t sectors, sectors_per_block;
379
380 while (nb_sectors > 0) {
381 offset = get_sector_offset(bs, sector_num, 0);
382
383 sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
384 sectors = sectors_per_block - (sector_num % sectors_per_block);
385 if (sectors > nb_sectors) {
386 sectors = nb_sectors;
387 }
388
389 if (offset == -1) {
390 memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
391 } else {
392 ret = bdrv_pread(bs->file, offset, buf,
393 sectors * BDRV_SECTOR_SIZE);
394 if (ret != sectors * BDRV_SECTOR_SIZE) {
395 return -1;
396 }
397 }
398
399 nb_sectors -= sectors;
400 sector_num += sectors;
401 buf += sectors * BDRV_SECTOR_SIZE;
402 }
403 return 0;
404 }
405
vpc_write(BlockDriverState * bs,int64_t sector_num,const uint8_t * buf,int nb_sectors)406 static int vpc_write(BlockDriverState *bs, int64_t sector_num,
407 const uint8_t *buf, int nb_sectors)
408 {
409 BDRVVPCState *s = bs->opaque;
410 int64_t offset;
411 int64_t sectors, sectors_per_block;
412 int ret;
413
414 while (nb_sectors > 0) {
415 offset = get_sector_offset(bs, sector_num, 1);
416
417 sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
418 sectors = sectors_per_block - (sector_num % sectors_per_block);
419 if (sectors > nb_sectors) {
420 sectors = nb_sectors;
421 }
422
423 if (offset == -1) {
424 offset = alloc_block(bs, sector_num);
425 if (offset < 0)
426 return -1;
427 }
428
429 ret = bdrv_pwrite(bs->file, offset, buf, sectors * BDRV_SECTOR_SIZE);
430 if (ret != sectors * BDRV_SECTOR_SIZE) {
431 return -1;
432 }
433
434 nb_sectors -= sectors;
435 sector_num += sectors;
436 buf += sectors * BDRV_SECTOR_SIZE;
437 }
438
439 return 0;
440 }
441
442
443 /*
444 * Calculates the number of cylinders, heads and sectors per cylinder
445 * based on a given number of sectors. This is the algorithm described
446 * in the VHD specification.
447 *
448 * Note that the geometry doesn't always exactly match total_sectors but
449 * may round it down.
450 *
451 * Returns 0 on success, -EFBIG if the size is larger than 127 GB
452 */
calculate_geometry(int64_t total_sectors,uint16_t * cyls,uint8_t * heads,uint8_t * secs_per_cyl)453 static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
454 uint8_t* heads, uint8_t* secs_per_cyl)
455 {
456 uint32_t cyls_times_heads;
457
458 if (total_sectors > 65535 * 16 * 255)
459 return -EFBIG;
460
461 if (total_sectors > 65535 * 16 * 63) {
462 *secs_per_cyl = 255;
463 *heads = 16;
464 cyls_times_heads = total_sectors / *secs_per_cyl;
465 } else {
466 *secs_per_cyl = 17;
467 cyls_times_heads = total_sectors / *secs_per_cyl;
468 *heads = (cyls_times_heads + 1023) / 1024;
469
470 if (*heads < 4)
471 *heads = 4;
472
473 if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
474 *secs_per_cyl = 31;
475 *heads = 16;
476 cyls_times_heads = total_sectors / *secs_per_cyl;
477 }
478
479 if (cyls_times_heads >= (*heads * 1024)) {
480 *secs_per_cyl = 63;
481 *heads = 16;
482 cyls_times_heads = total_sectors / *secs_per_cyl;
483 }
484 }
485
486 *cyls = cyls_times_heads / *heads;
487
488 return 0;
489 }
490
vpc_create(const char * filename,QEMUOptionParameter * options)491 static int vpc_create(const char *filename, QEMUOptionParameter *options)
492 {
493 uint8_t buf[1024];
494 struct vhd_footer* footer = (struct vhd_footer*) buf;
495 struct vhd_dyndisk_header* dyndisk_header =
496 (struct vhd_dyndisk_header*) buf;
497 int fd, i;
498 uint16_t cyls = 0;
499 uint8_t heads = 0;
500 uint8_t secs_per_cyl = 0;
501 size_t block_size, num_bat_entries;
502 int64_t total_sectors = 0;
503
504 // Read out options
505 while (options && options->name) {
506 if (!strcmp(options->name, "size")) {
507 total_sectors = options->value.n / 512;
508 }
509 options++;
510 }
511
512 // Create the file
513 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
514 if (fd < 0)
515 return -EIO;
516
517 /* Calculate matching total_size and geometry. Increase the number of
518 sectors requested until we get enough (or fail). */
519 for (i = 0; total_sectors > (int64_t)cyls * heads * secs_per_cyl; i++) {
520 if (calculate_geometry(total_sectors + i,
521 &cyls, &heads, &secs_per_cyl)) {
522 return -EFBIG;
523 }
524 }
525 total_sectors = (int64_t) cyls * heads * secs_per_cyl;
526
527 // Prepare the Hard Disk Footer
528 memset(buf, 0, 1024);
529
530 memcpy(footer->creator, "conectix", 8);
531 // TODO Check if "qemu" creator_app is ok for VPC
532 memcpy(footer->creator_app, "qemu", 4);
533 memcpy(footer->creator_os, "Wi2k", 4);
534
535 footer->features = be32_to_cpu(0x02);
536 footer->version = be32_to_cpu(0x00010000);
537 footer->data_offset = be64_to_cpu(HEADER_SIZE);
538 footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
539
540 // Version of Virtual PC 2007
541 footer->major = be16_to_cpu(0x0005);
542 footer->minor =be16_to_cpu(0x0003);
543
544 footer->orig_size = be64_to_cpu(total_sectors * 512);
545 footer->size = be64_to_cpu(total_sectors * 512);
546
547 footer->cyls = be16_to_cpu(cyls);
548 footer->heads = heads;
549 footer->secs_per_cyl = secs_per_cyl;
550
551 footer->type = be32_to_cpu(VHD_DYNAMIC);
552
553 // TODO uuid is missing
554
555 footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
556
557 // Write the footer (twice: at the beginning and at the end)
558 block_size = 0x200000;
559 num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
560
561 if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
562 return -EIO;
563
564 if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
565 return -EIO;
566 if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
567 return -EIO;
568
569 // Write the initial BAT
570 if (lseek(fd, 3 * 512, SEEK_SET) < 0)
571 return -EIO;
572
573 memset(buf, 0xFF, 512);
574 for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
575 if (write(fd, buf, 512) != 512)
576 return -EIO;
577
578
579 // Prepare the Dynamic Disk Header
580 memset(buf, 0, 1024);
581
582 memcpy(dyndisk_header->magic, "cxsparse", 8);
583
584 dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
585 dyndisk_header->table_offset = be64_to_cpu(3 * 512);
586 dyndisk_header->version = be32_to_cpu(0x00010000);
587 dyndisk_header->block_size = be32_to_cpu(block_size);
588 dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
589
590 dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
591
592 // Write the header
593 if (lseek(fd, 512, SEEK_SET) < 0)
594 return -EIO;
595 if (write(fd, buf, 1024) != 1024)
596 return -EIO;
597
598 close(fd);
599 return 0;
600 }
601
vpc_close(BlockDriverState * bs)602 static void vpc_close(BlockDriverState *bs)
603 {
604 BDRVVPCState *s = bs->opaque;
605 qemu_free(s->pagetable);
606 #ifdef CACHE
607 qemu_free(s->pageentry_u8);
608 #endif
609 }
610
611 static QEMUOptionParameter vpc_create_options[] = {
612 {
613 .name = BLOCK_OPT_SIZE,
614 .type = OPT_SIZE,
615 .help = "Virtual disk size"
616 },
617 { NULL }
618 };
619
620 static BlockDriver bdrv_vpc = {
621 .format_name = "vpc",
622 .instance_size = sizeof(BDRVVPCState),
623 .bdrv_probe = vpc_probe,
624 .bdrv_open = vpc_open,
625 .bdrv_read = vpc_read,
626 .bdrv_write = vpc_write,
627 .bdrv_close = vpc_close,
628 .bdrv_create = vpc_create,
629
630 .create_options = vpc_create_options,
631 };
632
bdrv_vpc_init(void)633 static void bdrv_vpc_init(void)
634 {
635 bdrv_register(&bdrv_vpc);
636 }
637
638 block_init(bdrv_vpc_init);
639