/*
* Block driver for Conectix/Microsoft Virtual PC images
- *
+ *
* Copyright (c) 2005 Alex Beregszaszi
- *
+ *
* 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
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
-#include "vl.h"
+#include "qemu-common.h"
#include "block_int.h"
/**************************************************************/
//#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 vpc_subheader {
- char magic[8]; // "conectix" / "cxsparse"
- union {
- struct {
- uint32_t unk1[2];
- uint32_t unk2; // always zero?
- uint32_t subheader_offset;
- uint32_t unk3; // some size?
- char creator[4]; // "vpc "
- uint16_t major;
- uint16_t minor;
- char guest[4]; // "Wi2k"
- uint32_t unk4[7];
- uint8_t vnet_id[16]; // virtual network id, purpose unknown
- // next 16 longs are used, but dunno the purpose
- // next 6 longs unknown, following 7 long maybe a serial
- char padding[HEADER_SIZE - 84];
- } main;
- struct {
- uint32_t unk1[2]; // all bits set
- uint32_t unk2; // always zero?
- uint32_t pagetable_offset;
- uint32_t unk3;
- uint32_t pagetable_entries; // 32bit/entry
- uint32_t pageentry_size; // 512*8*512
- uint32_t nb_sectors;
- char padding[HEADER_SIZE - 40];
- } sparse;
- char padding[HEADER_SIZE - 8];
- } type;
+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 {
- int fd;
-
- int pagetable_entries;
+ 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;
- uint32_t pageentry_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(buf, "conectix", 8))
+ if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
return 100;
return 0;
}
-static int vpc_open(BlockDriverState *bs, const char *filename)
+static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
{
BDRVVPCState *s = bs->opaque;
- int fd, i;
- struct vpc_subheader header;
+ int ret, i;
+ struct vhd_footer* footer;
+ struct vhd_dyndisk_header* dyndisk_header;
+ uint8_t buf[HEADER_SIZE];
+ uint32_t checksum;
- fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
- if (fd < 0) {
- fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
- if (fd < 0)
- return -1;
- }
-
- bs->read_only = 1; // no write support yet
-
- s->fd = fd;
+ ret = bdrv_file_open(&s->hd, filename, flags);
+ if (ret < 0)
+ return ret;
- if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
+ if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
goto fail;
- if (strncmp(header.magic, "conectix", 8))
+ footer = (struct vhd_footer*) s->footer_buf;
+ if (strncmp(footer->creator, "conectix", 8))
goto fail;
- lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);
- if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
+ 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;
- if (strncmp(header.magic, "cxsparse", 8))
- goto fail;
+ dyndisk_header = (struct vhd_dyndisk_header*) buf;
- bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *
- be32_to_cpu(header.type.sparse.pageentry_size)) / 512;
+ if (strncmp(dyndisk_header->magic, "cxsparse", 8))
+ goto fail;
- lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);
- s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);
- s->pagetable = qemu_malloc(s->pagetable_entries * 4);
- if (!s->pagetable)
- goto fail;
- if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
- s->pagetable_entries * 4)
- goto fail;
- for (i = 0; i < s->pagetable_entries; i++)
- be32_to_cpus(&s->pagetable[i]);
+ 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;
- s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);
#ifdef CACHE
s->pageentry_u8 = qemu_malloc(512);
- if (!s->pageentry_u8)
- goto fail;
s->pageentry_u32 = s->pageentry_u8;
s->pageentry_u16 = s->pageentry_u8;
s->last_pagetable = -1;
return 0;
fail:
- close(fd);
+ bdrv_delete(s->hd);
return -1;
}
-static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
+/*
+ * 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->pageentry_size;
- pageentry_index = (offset % s->pageentry_size) / 512;
-
- if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)
- return -1; // not allocated
+ 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];
- bitmap_offset = 512 * s->pagetable[pagetable_index];
- block_offset = bitmap_offset + 512 + (512 * pageentry_index);
-
-// printf("sector: %llx, index: %x, offset: %x, bioff: %llx, bloff: %llx\n",
+ 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);
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);
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
- lseek(s->fd, block_offset, SEEK_SET);
+
+ 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;
}
-static int vpc_read(BlockDriverState *bs, int64_t sector_num,
+/*
+ * 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) {
- if (!seek_to_sector(bs, sector_num))
- {
- ret = read(s->fd, buf, 512);
- if (ret != 512)
- return -1;
- }
- else
+ 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.
+ */
+static void 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)
+ total_sectors = 65535 * 16 * 255;
+
+ 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;
+}
+
+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
+ calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl);
+ 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;
#ifdef CACHE
qemu_free(s->pageentry_u8);
#endif
- close(s->fd);
+ bdrv_delete(s->hd);
}
BlockDriver bdrv_vpc = {
- "vpc",
- sizeof(BDRVVPCState),
- vpc_probe,
- vpc_open,
- vpc_read,
- NULL,
- vpc_close,
+ .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,
};
projects / qemu.git / blobdiff