Annotation of qemu/block/vpc.c, revision 1.1.1.2

1.1       root        1: /*
1.1.1.2 ! root        2:  * Block driver for Connectix / Microsoft Virtual PC images
1.1       root        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: 
                    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: 
1.1.1.2 ! root      514:     memcpy(footer->creator, "conectix", 8);
1.1       root      515:     // TODO Check if "qemu" creator_app is ok for VPC
1.1.1.2 ! root      516:     memcpy(footer->creator_app, "qemu", 4);
        !           517:     memcpy(footer->creator_os, "Wi2k", 4);
1.1       root      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: 
1.1.1.2 ! root      566:     memcpy(dyndisk_header->magic, "cxsparse", 8);
1.1       root      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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