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1.1 root 1: /*
2: * Block driver for Conectix/Microsoft Virtual PC images
3: *
4: * Copyright (c) 2005 Alex Beregszaszi
5: * Copyright (c) 2009 Kevin Wolf <[email protected]>
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:
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:
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:
153: static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
154: {
155: BDRVVPCState *s = bs->opaque;
156: int ret, 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: ret = bdrv_file_open(&s->hd, filename, flags);
163: if (ret < 0)
164: return ret;
165:
166: if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
167: goto fail;
168:
169: footer = (struct vhd_footer*) s->footer_buf;
170: if (strncmp(footer->creator, "conectix", 8))
171: goto fail;
172:
173: checksum = be32_to_cpu(footer->checksum);
174: footer->checksum = 0;
175: if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
176: fprintf(stderr, "block-vpc: The header checksum of '%s' is "
177: "incorrect.\n", filename);
178:
179: // The visible size of a image in Virtual PC depends on the geometry
180: // rather than on the size stored in the footer (the size in the footer
181: // is too large usually)
182: bs->total_sectors = (int64_t)
183: be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
184:
185: if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
186: != HEADER_SIZE)
187: goto fail;
188:
189: dyndisk_header = (struct vhd_dyndisk_header*) buf;
190:
191: if (strncmp(dyndisk_header->magic, "cxsparse", 8))
192: goto fail;
193:
194:
195: s->block_size = be32_to_cpu(dyndisk_header->block_size);
196: s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
197:
198: s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
199: s->pagetable = qemu_malloc(s->max_table_entries * 4);
200:
201: s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
202: if (bdrv_pread(s->hd, s->bat_offset, s->pagetable,
203: s->max_table_entries * 4) != s->max_table_entries * 4)
204: goto fail;
205:
206: s->free_data_block_offset =
207: (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
208:
209: for (i = 0; i < s->max_table_entries; i++) {
210: be32_to_cpus(&s->pagetable[i]);
211: if (s->pagetable[i] != 0xFFFFFFFF) {
212: int64_t next = (512 * (int64_t) s->pagetable[i]) +
213: s->bitmap_size + s->block_size;
214:
215: if (next> s->free_data_block_offset)
216: s->free_data_block_offset = next;
217: }
218: }
219:
220: s->last_bitmap_offset = (int64_t) -1;
221:
222: #ifdef CACHE
223: s->pageentry_u8 = qemu_malloc(512);
224: s->pageentry_u32 = s->pageentry_u8;
225: s->pageentry_u16 = s->pageentry_u8;
226: s->last_pagetable = -1;
227: #endif
228:
229: return 0;
230: fail:
231: bdrv_delete(s->hd);
232: return -1;
233: }
234:
235: /*
236: * Returns the absolute byte offset of the given sector in the image file.
237: * If the sector is not allocated, -1 is returned instead.
238: *
239: * The parameter write must be 1 if the offset will be used for a write
240: * operation (the block bitmaps is updated then), 0 otherwise.
241: */
242: static inline int64_t get_sector_offset(BlockDriverState *bs,
243: int64_t sector_num, int write)
244: {
245: BDRVVPCState *s = bs->opaque;
246: uint64_t offset = sector_num * 512;
247: uint64_t bitmap_offset, block_offset;
248: uint32_t pagetable_index, pageentry_index;
249:
250: pagetable_index = offset / s->block_size;
251: pageentry_index = (offset % s->block_size) / 512;
252:
253: if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
254: return -1; // not allocated
255:
256: bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
257: block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
258:
259: // We must ensure that we don't write to any sectors which are marked as
260: // unused in the bitmap. We get away with setting all bits in the block
261: // bitmap each time we write to a new block. This might cause Virtual PC to
262: // miss sparse read optimization, but it's not a problem in terms of
263: // correctness.
264: if (write && (s->last_bitmap_offset != bitmap_offset)) {
265: uint8_t bitmap[s->bitmap_size];
266:
267: s->last_bitmap_offset = bitmap_offset;
268: memset(bitmap, 0xff, s->bitmap_size);
269: bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size);
270: }
271:
272: // printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
273: // sector_num, pagetable_index, pageentry_index,
274: // bitmap_offset, block_offset);
275:
276: // disabled by reason
277: #if 0
278: #ifdef CACHE
279: if (bitmap_offset != s->last_bitmap)
280: {
281: lseek(s->fd, bitmap_offset, SEEK_SET);
282:
283: s->last_bitmap = bitmap_offset;
284:
285: // Scary! Bitmap is stored as big endian 32bit entries,
286: // while we used to look it up byte by byte
287: read(s->fd, s->pageentry_u8, 512);
288: for (i = 0; i < 128; i++)
289: be32_to_cpus(&s->pageentry_u32[i]);
290: }
291:
292: if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
293: return -1;
294: #else
295: lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
296:
297: read(s->fd, &bitmap_entry, 1);
298:
299: if ((bitmap_entry >> (pageentry_index % 8)) & 1)
300: return -1; // not allocated
301: #endif
302: #endif
303:
304: return block_offset;
305: }
306:
307: /*
308: * Writes the footer to the end of the image file. This is needed when the
309: * file grows as it overwrites the old footer
310: *
311: * Returns 0 on success and < 0 on error
312: */
313: static int rewrite_footer(BlockDriverState* bs)
314: {
315: int ret;
316: BDRVVPCState *s = bs->opaque;
317: int64_t offset = s->free_data_block_offset;
318:
319: ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE);
320: if (ret < 0)
321: return ret;
322:
323: return 0;
324: }
325:
326: /*
327: * Allocates a new block. This involves writing a new footer and updating
328: * the Block Allocation Table to use the space at the old end of the image
329: * file (overwriting the old footer)
330: *
331: * Returns the sectors' offset in the image file on success and < 0 on error
332: */
333: static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
334: {
335: BDRVVPCState *s = bs->opaque;
336: int64_t bat_offset;
337: uint32_t index, bat_value;
338: int ret;
339: uint8_t bitmap[s->bitmap_size];
340:
341: // Check if sector_num is valid
342: if ((sector_num < 0) || (sector_num > bs->total_sectors))
343: return -1;
344:
345: // Write entry into in-memory BAT
346: index = (sector_num * 512) / s->block_size;
347: if (s->pagetable[index] != 0xFFFFFFFF)
348: return -1;
349:
350: s->pagetable[index] = s->free_data_block_offset / 512;
351:
352: // Initialize the block's bitmap
353: memset(bitmap, 0xff, s->bitmap_size);
354: bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size);
355:
356: // Write new footer (the old one will be overwritten)
357: s->free_data_block_offset += s->block_size + s->bitmap_size;
358: ret = rewrite_footer(bs);
359: if (ret < 0)
360: goto fail;
361:
362: // Write BAT entry to disk
363: bat_offset = s->bat_offset + (4 * index);
364: bat_value = be32_to_cpu(s->pagetable[index]);
365: ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4);
366: if (ret < 0)
367: goto fail;
368:
369: return get_sector_offset(bs, sector_num, 0);
370:
371: fail:
372: s->free_data_block_offset -= (s->block_size + s->bitmap_size);
373: return -1;
374: }
375:
376: static int vpc_read(BlockDriverState *bs, int64_t sector_num,
377: uint8_t *buf, int nb_sectors)
378: {
379: BDRVVPCState *s = bs->opaque;
380: int ret;
381: int64_t offset;
382:
383: while (nb_sectors > 0) {
384: offset = get_sector_offset(bs, sector_num, 0);
385:
386: if (offset == -1) {
387: memset(buf, 0, 512);
388: } else {
389: ret = bdrv_pread(s->hd, offset, buf, 512);
390: if (ret != 512)
391: return -1;
392: }
393:
394: nb_sectors--;
395: sector_num++;
396: buf += 512;
397: }
398: return 0;
399: }
400:
401: static int vpc_write(BlockDriverState *bs, int64_t sector_num,
402: const uint8_t *buf, int nb_sectors)
403: {
404: BDRVVPCState *s = bs->opaque;
405: int64_t offset;
406: int ret;
407:
408: while (nb_sectors > 0) {
409: offset = get_sector_offset(bs, sector_num, 1);
410:
411: if (offset == -1) {
412: offset = alloc_block(bs, sector_num);
413: if (offset < 0)
414: return -1;
415: }
416:
417: ret = bdrv_pwrite(s->hd, offset, buf, 512);
418: if (ret != 512)
419: return -1;
420:
421: nb_sectors--;
422: sector_num++;
423: buf += 512;
424: }
425:
426: return 0;
427: }
428:
429:
430: /*
431: * Calculates the number of cylinders, heads and sectors per cylinder
432: * based on a given number of sectors. This is the algorithm described
433: * in the VHD specification.
434: *
435: * Note that the geometry doesn't always exactly match total_sectors but
436: * may round it down.
437: *
438: * Returns 0 on success, -EFBIG if the size is larger than 127 GB
439: */
440: static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
441: uint8_t* heads, uint8_t* secs_per_cyl)
442: {
443: uint32_t cyls_times_heads;
444:
445: if (total_sectors > 65535 * 16 * 255)
446: return -EFBIG;
447:
448: if (total_sectors > 65535 * 16 * 63) {
449: *secs_per_cyl = 255;
450: *heads = 16;
451: cyls_times_heads = total_sectors / *secs_per_cyl;
452: } else {
453: *secs_per_cyl = 17;
454: cyls_times_heads = total_sectors / *secs_per_cyl;
455: *heads = (cyls_times_heads + 1023) / 1024;
456:
457: if (*heads < 4)
458: *heads = 4;
459:
460: if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
461: *secs_per_cyl = 31;
462: *heads = 16;
463: cyls_times_heads = total_sectors / *secs_per_cyl;
464: }
465:
466: if (cyls_times_heads >= (*heads * 1024)) {
467: *secs_per_cyl = 63;
468: *heads = 16;
469: cyls_times_heads = total_sectors / *secs_per_cyl;
470: }
471: }
472:
473: // Note: Rounding up deviates from the Virtual PC behaviour
474: // However, we need this to avoid truncating images in qemu-img convert
475: *cyls = (cyls_times_heads + *heads - 1) / *heads;
476:
477: return 0;
478: }
479:
480: static int vpc_create(const char *filename, QEMUOptionParameter *options)
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: int64_t total_sectors = 0;
492:
493: // Read out options
494: while (options && options->name) {
495: if (!strcmp(options->name, "size")) {
496: total_sectors = options->value.n / 512;
497: }
498: options++;
499: }
500:
501: // Create the file
502: fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
503: if (fd < 0)
504: return -EIO;
505:
506: // Calculate matching total_size and geometry
507: if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl))
508: return -EFBIG;
509: total_sectors = (int64_t) cyls * heads * secs_per_cyl;
510:
511: // Prepare the Hard Disk Footer
512: memset(buf, 0, 1024);
513:
514: strncpy(footer->creator, "conectix", 8);
515: // TODO Check if "qemu" creator_app is ok for VPC
516: strncpy(footer->creator_app, "qemu", 4);
517: strncpy(footer->creator_os, "Wi2k", 4);
518:
519: footer->features = be32_to_cpu(0x02);
520: footer->version = be32_to_cpu(0x00010000);
521: footer->data_offset = be64_to_cpu(HEADER_SIZE);
522: footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
523:
524: // Version of Virtual PC 2007
525: footer->major = be16_to_cpu(0x0005);
526: footer->minor =be16_to_cpu(0x0003);
527:
528: footer->orig_size = be64_to_cpu(total_sectors * 512);
529: footer->size = be64_to_cpu(total_sectors * 512);
530:
531: footer->cyls = be16_to_cpu(cyls);
532: footer->heads = heads;
533: footer->secs_per_cyl = secs_per_cyl;
534:
535: footer->type = be32_to_cpu(VHD_DYNAMIC);
536:
537: // TODO uuid is missing
538:
539: footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
540:
541: // Write the footer (twice: at the beginning and at the end)
542: block_size = 0x200000;
543: num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
544:
545: if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
546: return -EIO;
547:
548: if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
549: return -EIO;
550: if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
551: return -EIO;
552:
553: // Write the initial BAT
554: if (lseek(fd, 3 * 512, SEEK_SET) < 0)
555: return -EIO;
556:
557: memset(buf, 0xFF, 512);
558: for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
559: if (write(fd, buf, 512) != 512)
560: return -EIO;
561:
562:
563: // Prepare the Dynamic Disk Header
564: memset(buf, 0, 1024);
565:
566: strncpy(dyndisk_header->magic, "cxsparse", 8);
567:
568: dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
569: dyndisk_header->table_offset = be64_to_cpu(3 * 512);
570: dyndisk_header->version = be32_to_cpu(0x00010000);
571: dyndisk_header->block_size = be32_to_cpu(block_size);
572: dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
573:
574: dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
575:
576: // Write the header
577: if (lseek(fd, 512, SEEK_SET) < 0)
578: return -EIO;
579: if (write(fd, buf, 1024) != 1024)
580: return -EIO;
581:
582: close(fd);
583: return 0;
584: }
585:
586: static void vpc_close(BlockDriverState *bs)
587: {
588: BDRVVPCState *s = bs->opaque;
589: qemu_free(s->pagetable);
590: #ifdef CACHE
591: qemu_free(s->pageentry_u8);
592: #endif
593: bdrv_delete(s->hd);
594: }
595:
596: static QEMUOptionParameter vpc_create_options[] = {
597: {
598: .name = BLOCK_OPT_SIZE,
599: .type = OPT_SIZE,
600: .help = "Virtual disk size"
601: },
602: { NULL }
603: };
604:
605: static BlockDriver bdrv_vpc = {
606: .format_name = "vpc",
607: .instance_size = sizeof(BDRVVPCState),
608: .bdrv_probe = vpc_probe,
609: .bdrv_open = vpc_open,
610: .bdrv_read = vpc_read,
611: .bdrv_write = vpc_write,
612: .bdrv_close = vpc_close,
613: .bdrv_create = vpc_create,
614:
615: .create_options = vpc_create_options,
616: };
617:
618: static void bdrv_vpc_init(void)
619: {
620: bdrv_register(&bdrv_vpc);
621: }
622:
623: block_init(bdrv_vpc_init);
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