/* * Block driver for Conectix/Microsoft Virtual PC images * * Copyright (c) 2005 Alex Beregszaszi * Copyright (c) 2009 Kevin Wolf * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu-common.h" #include "block_int.h" /**************************************************************/ #define HEADER_SIZE 512 //#define CACHE enum vhd_type { VHD_FIXED = 2, VHD_DYNAMIC = 3, VHD_DIFFERENCING = 4, }; // Seconds since Jan 1, 2000 0:00:00 (UTC) #define VHD_TIMESTAMP_BASE 946684800 // always big-endian struct vhd_footer { char creator[8]; // "conectix" uint32_t features; uint32_t version; // Offset of next header structure, 0xFFFFFFFF if none uint64_t data_offset; // Seconds since Jan 1, 2000 0:00:00 (UTC) uint32_t timestamp; char creator_app[4]; // "vpc " uint16_t major; uint16_t minor; char creator_os[4]; // "Wi2k" uint64_t orig_size; uint64_t size; uint16_t cyls; uint8_t heads; uint8_t secs_per_cyl; uint32_t type; // Checksum of the Hard Disk Footer ("one's complement of the sum of all // the bytes in the footer without the checksum field") uint32_t checksum; // UUID used to identify a parent hard disk (backing file) uint8_t uuid[16]; uint8_t in_saved_state; }; struct vhd_dyndisk_header { char magic[8]; // "cxsparse" // Offset of next header structure, 0xFFFFFFFF if none uint64_t data_offset; // Offset of the Block Allocation Table (BAT) uint64_t table_offset; uint32_t version; uint32_t max_table_entries; // 32bit/entry // 2 MB by default, must be a power of two uint32_t block_size; uint32_t checksum; uint8_t parent_uuid[16]; uint32_t parent_timestamp; uint32_t reserved; // Backing file name (in UTF-16) uint8_t parent_name[512]; struct { uint32_t platform; uint32_t data_space; uint32_t data_length; uint32_t reserved; uint64_t data_offset; } parent_locator[8]; }; typedef struct BDRVVPCState { BlockDriverState *hd; uint8_t footer_buf[HEADER_SIZE]; uint64_t free_data_block_offset; int max_table_entries; uint32_t *pagetable; uint64_t bat_offset; uint64_t last_bitmap_offset; uint32_t block_size; uint32_t bitmap_size; #ifdef CACHE uint8_t *pageentry_u8; uint32_t *pageentry_u32; uint16_t *pageentry_u16; uint64_t last_bitmap; #endif } BDRVVPCState; static uint32_t vpc_checksum(uint8_t* buf, size_t size) { uint32_t res = 0; int i; for (i = 0; i < size; i++) res += buf[i]; return ~res; } static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename) { if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8)) return 100; return 0; } static int vpc_open(BlockDriverState *bs, const char *filename, int flags) { BDRVVPCState *s = bs->opaque; int ret, i; struct vhd_footer* footer; struct vhd_dyndisk_header* dyndisk_header; uint8_t buf[HEADER_SIZE]; uint32_t checksum; ret = bdrv_file_open(&s->hd, filename, flags); if (ret < 0) return ret; if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE) goto fail; footer = (struct vhd_footer*) s->footer_buf; if (strncmp(footer->creator, "conectix", 8)) goto fail; checksum = be32_to_cpu(footer->checksum); footer->checksum = 0; if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum) fprintf(stderr, "block-vpc: The header checksum of '%s' is " "incorrect.\n", filename); // The visible size of a image in Virtual PC depends on the geometry // rather than on the size stored in the footer (the size in the footer // is too large usually) bs->total_sectors = (int64_t) be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl; if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE) != HEADER_SIZE) goto fail; dyndisk_header = (struct vhd_dyndisk_header*) buf; if (strncmp(dyndisk_header->magic, "cxsparse", 8)) goto fail; s->block_size = be32_to_cpu(dyndisk_header->block_size); s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511; s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries); s->pagetable = qemu_malloc(s->max_table_entries * 4); s->bat_offset = be64_to_cpu(dyndisk_header->table_offset); if (bdrv_pread(s->hd, s->bat_offset, s->pagetable, s->max_table_entries * 4) != s->max_table_entries * 4) goto fail; s->free_data_block_offset = (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511; for (i = 0; i < s->max_table_entries; i++) { be32_to_cpus(&s->pagetable[i]); if (s->pagetable[i] != 0xFFFFFFFF) { int64_t next = (512 * (int64_t) s->pagetable[i]) + s->bitmap_size + s->block_size; if (next> s->free_data_block_offset) s->free_data_block_offset = next; } } s->last_bitmap_offset = (int64_t) -1; #ifdef CACHE s->pageentry_u8 = qemu_malloc(512); s->pageentry_u32 = s->pageentry_u8; s->pageentry_u16 = s->pageentry_u8; s->last_pagetable = -1; #endif return 0; fail: bdrv_delete(s->hd); return -1; } /* * Returns the absolute byte offset of the given sector in the image file. * If the sector is not allocated, -1 is returned instead. * * The parameter write must be 1 if the offset will be used for a write * operation (the block bitmaps is updated then), 0 otherwise. */ static inline int64_t get_sector_offset(BlockDriverState *bs, int64_t sector_num, int write) { BDRVVPCState *s = bs->opaque; uint64_t offset = sector_num * 512; uint64_t bitmap_offset, block_offset; uint32_t pagetable_index, pageentry_index; pagetable_index = offset / s->block_size; pageentry_index = (offset % s->block_size) / 512; if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff) return -1; // not allocated bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index]; block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index); // We must ensure that we don't write to any sectors which are marked as // unused in the bitmap. We get away with setting all bits in the block // bitmap each time we write to a new block. This might cause Virtual PC to // miss sparse read optimization, but it's not a problem in terms of // correctness. if (write && (s->last_bitmap_offset != bitmap_offset)) { uint8_t bitmap[s->bitmap_size]; s->last_bitmap_offset = bitmap_offset; memset(bitmap, 0xff, s->bitmap_size); bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size); } // printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n", // sector_num, pagetable_index, pageentry_index, // bitmap_offset, block_offset); // disabled by reason #if 0 #ifdef CACHE if (bitmap_offset != s->last_bitmap) { lseek(s->fd, bitmap_offset, SEEK_SET); s->last_bitmap = bitmap_offset; // Scary! Bitmap is stored as big endian 32bit entries, // while we used to look it up byte by byte read(s->fd, s->pageentry_u8, 512); for (i = 0; i < 128; i++) be32_to_cpus(&s->pageentry_u32[i]); } if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1) return -1; #else lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET); read(s->fd, &bitmap_entry, 1); if ((bitmap_entry >> (pageentry_index % 8)) & 1) return -1; // not allocated #endif #endif return block_offset; } /* * Writes the footer to the end of the image file. This is needed when the * file grows as it overwrites the old footer * * Returns 0 on success and < 0 on error */ static int rewrite_footer(BlockDriverState* bs) { int ret; BDRVVPCState *s = bs->opaque; int64_t offset = s->free_data_block_offset; ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE); if (ret < 0) return ret; return 0; } /* * Allocates a new block. This involves writing a new footer and updating * the Block Allocation Table to use the space at the old end of the image * file (overwriting the old footer) * * Returns the sectors' offset in the image file on success and < 0 on error */ static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num) { BDRVVPCState *s = bs->opaque; int64_t bat_offset; uint32_t index, bat_value; int ret; uint8_t bitmap[s->bitmap_size]; // Check if sector_num is valid if ((sector_num < 0) || (sector_num > bs->total_sectors)) return -1; // Write entry into in-memory BAT index = (sector_num * 512) / s->block_size; if (s->pagetable[index] != 0xFFFFFFFF) return -1; s->pagetable[index] = s->free_data_block_offset / 512; // Initialize the block's bitmap memset(bitmap, 0xff, s->bitmap_size); bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size); // Write new footer (the old one will be overwritten) s->free_data_block_offset += s->block_size + s->bitmap_size; ret = rewrite_footer(bs); if (ret < 0) goto fail; // Write BAT entry to disk bat_offset = s->bat_offset + (4 * index); bat_value = be32_to_cpu(s->pagetable[index]); ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4); if (ret < 0) goto fail; return get_sector_offset(bs, sector_num, 0); fail: s->free_data_block_offset -= (s->block_size + s->bitmap_size); return -1; } static int vpc_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors) { BDRVVPCState *s = bs->opaque; int ret; int64_t offset; while (nb_sectors > 0) { offset = get_sector_offset(bs, sector_num, 0); if (offset == -1) { memset(buf, 0, 512); } else { ret = bdrv_pread(s->hd, offset, buf, 512); if (ret != 512) return -1; } nb_sectors--; sector_num++; buf += 512; } return 0; } static int vpc_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { BDRVVPCState *s = bs->opaque; int64_t offset; int ret; while (nb_sectors > 0) { offset = get_sector_offset(bs, sector_num, 1); if (offset == -1) { offset = alloc_block(bs, sector_num); if (offset < 0) return -1; } ret = bdrv_pwrite(s->hd, offset, buf, 512); if (ret != 512) return -1; nb_sectors--; sector_num++; buf += 512; } return 0; } /* * Calculates the number of cylinders, heads and sectors per cylinder * based on a given number of sectors. This is the algorithm described * in the VHD specification. * * Note that the geometry doesn't always exactly match total_sectors but * may round it down. * * Returns 0 on success, -EFBIG if the size is larger than 127 GB */ static int calculate_geometry(int64_t total_sectors, uint16_t* cyls, uint8_t* heads, uint8_t* secs_per_cyl) { uint32_t cyls_times_heads; if (total_sectors > 65535 * 16 * 255) return -EFBIG; if (total_sectors > 65535 * 16 * 63) { *secs_per_cyl = 255; *heads = 16; cyls_times_heads = total_sectors / *secs_per_cyl; } else { *secs_per_cyl = 17; cyls_times_heads = total_sectors / *secs_per_cyl; *heads = (cyls_times_heads + 1023) / 1024; if (*heads < 4) *heads = 4; if (cyls_times_heads >= (*heads * 1024) || *heads > 16) { *secs_per_cyl = 31; *heads = 16; cyls_times_heads = total_sectors / *secs_per_cyl; } if (cyls_times_heads >= (*heads * 1024)) { *secs_per_cyl = 63; *heads = 16; cyls_times_heads = total_sectors / *secs_per_cyl; } } // Note: Rounding up deviates from the Virtual PC behaviour // However, we need this to avoid truncating images in qemu-img convert *cyls = (cyls_times_heads + *heads - 1) / *heads; return 0; } static int vpc_create(const char *filename, int64_t total_sectors, const char *backing_file, int flags) { uint8_t buf[1024]; struct vhd_footer* footer = (struct vhd_footer*) buf; struct vhd_dyndisk_header* dyndisk_header = (struct vhd_dyndisk_header*) buf; int fd, i; uint16_t cyls; uint8_t heads; uint8_t secs_per_cyl; size_t block_size, num_bat_entries; if (backing_file != NULL) return -ENOTSUP; fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644); if (fd < 0) return -EIO; // Calculate matching total_size and geometry if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl)) return -EFBIG; total_sectors = (int64_t) cyls * heads * secs_per_cyl; // Prepare the Hard Disk Footer memset(buf, 0, 1024); strncpy(footer->creator, "conectix", 8); // TODO Check if "qemu" creator_app is ok for VPC strncpy(footer->creator_app, "qemu", 4); strncpy(footer->creator_os, "Wi2k", 4); footer->features = be32_to_cpu(0x02); footer->version = be32_to_cpu(0x00010000); footer->data_offset = be64_to_cpu(HEADER_SIZE); footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE); // Version of Virtual PC 2007 footer->major = be16_to_cpu(0x0005); footer->minor =be16_to_cpu(0x0003); footer->orig_size = be64_to_cpu(total_sectors * 512); footer->size = be64_to_cpu(total_sectors * 512); footer->cyls = be16_to_cpu(cyls); footer->heads = heads; footer->secs_per_cyl = secs_per_cyl; footer->type = be32_to_cpu(VHD_DYNAMIC); // TODO uuid is missing footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE)); // Write the footer (twice: at the beginning and at the end) block_size = 0x200000; num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512); if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) return -EIO; if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0) return -EIO; if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) return -EIO; // Write the initial BAT if (lseek(fd, 3 * 512, SEEK_SET) < 0) return -EIO; memset(buf, 0xFF, 512); for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++) if (write(fd, buf, 512) != 512) return -EIO; // Prepare the Dynamic Disk Header memset(buf, 0, 1024); strncpy(dyndisk_header->magic, "cxsparse", 8); dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF); dyndisk_header->table_offset = be64_to_cpu(3 * 512); dyndisk_header->version = be32_to_cpu(0x00010000); dyndisk_header->block_size = be32_to_cpu(block_size); dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries); dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024)); // Write the header if (lseek(fd, 512, SEEK_SET) < 0) return -EIO; if (write(fd, buf, 1024) != 1024) return -EIO; close(fd); return 0; } static void vpc_close(BlockDriverState *bs) { BDRVVPCState *s = bs->opaque; qemu_free(s->pagetable); #ifdef CACHE qemu_free(s->pageentry_u8); #endif bdrv_delete(s->hd); } BlockDriver bdrv_vpc = { .format_name = "vpc", .instance_size = sizeof(BDRVVPCState), .bdrv_probe = vpc_probe, .bdrv_open = vpc_open, .bdrv_read = vpc_read, .bdrv_write = vpc_write, .bdrv_close = vpc_close, .bdrv_create = vpc_create, };