File:  [Qemu by Fabrice Bellard] / qemu / block-vpc.c
Revision 1.1.1.5 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:51:00 2018 UTC (3 years, 1 month ago) by root
Branches: qemu, MAIN
CVS tags: qemu0102, qemu0101, qemu0100, HEAD
qemu 0.10.0

    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: static void calculate_geometry(int64_t total_sectors, uint16_t* cyls,
  438:     uint8_t* heads, uint8_t* secs_per_cyl)
  439: {
  440:     uint32_t cyls_times_heads;
  441: 
  442:     if (total_sectors > 65535 * 16 * 255)
  443:         total_sectors = 65535 * 16 * 255;
  444: 
  445:     if (total_sectors > 65535 * 16 * 63) {
  446:         *secs_per_cyl = 255;
  447:         *heads = 16;
  448:         cyls_times_heads = total_sectors / *secs_per_cyl;
  449:     } else {
  450:         *secs_per_cyl = 17;
  451:         cyls_times_heads = total_sectors / *secs_per_cyl;
  452:         *heads = (cyls_times_heads + 1023) / 1024;
  453: 
  454:         if (*heads < 4)
  455:             *heads = 4;
  456: 
  457:         if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
  458:             *secs_per_cyl = 31;
  459:             *heads = 16;
  460:             cyls_times_heads = total_sectors / *secs_per_cyl;
  461:         }
  462: 
  463:         if (cyls_times_heads >= (*heads * 1024)) {
  464:             *secs_per_cyl = 63;
  465:             *heads = 16;
  466:             cyls_times_heads = total_sectors / *secs_per_cyl;
  467:         }
  468:     }
  469: 
  470:     // Note: Rounding up deviates from the Virtual PC behaviour
  471:     // However, we need this to avoid truncating images in qemu-img convert
  472:     *cyls = (cyls_times_heads + *heads - 1) / *heads;
  473: }
  474: 
  475: static int vpc_create(const char *filename, int64_t total_sectors,
  476:     const char *backing_file, int flags)
  477: {
  478:     uint8_t buf[1024];
  479:     struct vhd_footer* footer = (struct vhd_footer*) buf;
  480:     struct vhd_dyndisk_header* dyndisk_header =
  481:         (struct vhd_dyndisk_header*) buf;
  482:     int fd, i;
  483:     uint16_t cyls;
  484:     uint8_t heads;
  485:     uint8_t secs_per_cyl;
  486:     size_t block_size, num_bat_entries;
  487: 
  488:     if (backing_file != NULL)
  489:         return -ENOTSUP;
  490: 
  491:     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
  492:     if (fd < 0)
  493:         return -EIO;
  494: 
  495:     // Calculate matching total_size and geometry
  496:     calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl);
  497:     total_sectors = (int64_t) cyls * heads * secs_per_cyl;
  498: 
  499:     // Prepare the Hard Disk Footer
  500:     memset(buf, 0, 1024);
  501: 
  502:     strncpy(footer->creator, "conectix", 8);
  503:     // TODO Check if "qemu" creator_app is ok for VPC
  504:     strncpy(footer->creator_app, "qemu", 4);
  505:     strncpy(footer->creator_os, "Wi2k", 4);
  506: 
  507:     footer->features = be32_to_cpu(0x02);
  508:     footer->version = be32_to_cpu(0x00010000);
  509:     footer->data_offset = be64_to_cpu(HEADER_SIZE);
  510:     footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
  511: 
  512:     // Version of Virtual PC 2007
  513:     footer->major = be16_to_cpu(0x0005);
  514:     footer->minor =be16_to_cpu(0x0003);
  515: 
  516:     footer->orig_size = be64_to_cpu(total_sectors * 512);
  517:     footer->size = be64_to_cpu(total_sectors * 512);
  518: 
  519:     footer->cyls = be16_to_cpu(cyls);
  520:     footer->heads = heads;
  521:     footer->secs_per_cyl = secs_per_cyl;
  522: 
  523:     footer->type = be32_to_cpu(VHD_DYNAMIC);
  524: 
  525:     // TODO uuid is missing
  526: 
  527:     footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
  528: 
  529:     // Write the footer (twice: at the beginning and at the end)
  530:     block_size = 0x200000;
  531:     num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
  532: 
  533:     if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
  534:         return -EIO;
  535: 
  536:     if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
  537:         return -EIO;
  538:     if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
  539:         return -EIO;
  540: 
  541:     // Write the initial BAT
  542:     if (lseek(fd, 3 * 512, SEEK_SET) < 0)
  543:         return -EIO;
  544: 
  545:     memset(buf, 0xFF, 512);
  546:     for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
  547:         if (write(fd, buf, 512) != 512)
  548:             return -EIO;
  549: 
  550: 
  551:     // Prepare the Dynamic Disk Header
  552:     memset(buf, 0, 1024);
  553: 
  554:     strncpy(dyndisk_header->magic, "cxsparse", 8);
  555: 
  556:     dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
  557:     dyndisk_header->table_offset = be64_to_cpu(3 * 512);
  558:     dyndisk_header->version = be32_to_cpu(0x00010000);
  559:     dyndisk_header->block_size = be32_to_cpu(block_size);
  560:     dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
  561: 
  562:     dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
  563: 
  564:     // Write the header
  565:     if (lseek(fd, 512, SEEK_SET) < 0)
  566:         return -EIO;
  567:     if (write(fd, buf, 1024) != 1024)
  568:         return -EIO;
  569: 
  570:     close(fd);
  571:     return 0;
  572: }
  573: 
  574: static void vpc_close(BlockDriverState *bs)
  575: {
  576:     BDRVVPCState *s = bs->opaque;
  577:     qemu_free(s->pagetable);
  578: #ifdef CACHE
  579:     qemu_free(s->pageentry_u8);
  580: #endif
  581:     bdrv_delete(s->hd);
  582: }
  583: 
  584: BlockDriver bdrv_vpc = {
  585:     "vpc",
  586:     sizeof(BDRVVPCState),
  587:     vpc_probe,
  588:     vpc_open,
  589:     vpc_read,
  590:     vpc_write,
  591:     vpc_close,
  592:     vpc_create,
  593: };

unix.superglobalmegacorp.com