Archipelago » qemu

/*

 * Block driver for the VMDK format

 * 

 * Copyright (c) 2004 Fabrice Bellard

 * Copyright (c) 2005 Filip Navara

 * 

 * 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 "vl.h"

#include "block_int.h"

#define VMDK3_MAGIC (('C' << 24) | ('O' << 16) | ('W' << 8) | 'D')

#define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')

typedef struct {

    uint32_t version;

    uint32_t flags;

    uint32_t disk_sectors;

    uint32_t granularity;

    uint32_t l1dir_offset;

    uint32_t l1dir_size;

    uint32_t file_sectors;

    uint32_t cylinders;

    uint32_t heads;

    uint32_t sectors_per_track;

} VMDK3Header;

typedef struct {

    uint32_t version;

    uint32_t flags;

    int64_t capacity;

    int64_t granularity;

    int64_t desc_offset;

    int64_t desc_size;

    int32_t num_gtes_per_gte;

    int64_t rgd_offset;

    int64_t gd_offset;

    int64_t grain_offset;

    char filler[1];

    char check_bytes[4];

} __attribute__((packed)) VMDK4Header;

#define L2_CACHE_SIZE 16

typedef struct BDRVVmdkState {

    BlockDriverState *hd;

    int64_t l1_table_offset;

    int64_t l1_backup_table_offset;

    uint32_t *l1_table;

    uint32_t *l1_backup_table;

    unsigned int l1_size;

    uint32_t l1_entry_sectors;

    unsigned int l2_size;

    uint32_t *l2_cache;

    uint32_t l2_cache_offsets[L2_CACHE_SIZE];

    uint32_t l2_cache_counts[L2_CACHE_SIZE];

    unsigned int cluster_sectors;

    uint32_t parent_cid;

    int is_parent;

} BDRVVmdkState;

typedef struct VmdkMetaData {

    uint32_t offset;

    unsigned int l1_index;

    unsigned int l2_index;

    unsigned int l2_offset;

    int valid;

} VmdkMetaData;

typedef struct ActiveBDRVState{

    BlockDriverState *hd;            // active image handler

    uint64_t cluster_offset;         // current write offset

}ActiveBDRVState;

static ActiveBDRVState activeBDRV;

static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)

{

    uint32_t magic;

    if (buf_size < 4)

        return 0;

    magic = be32_to_cpu(*(uint32_t *)buf);

    if (magic == VMDK3_MAGIC ||

        magic == VMDK4_MAGIC)

        return 100;

    else

        return 0;

}

#define CHECK_CID 1

#define SECTOR_SIZE 512                                

#define DESC_SIZE 20*SECTOR_SIZE        // 20 sectors of 512 bytes each

#define HEADER_SIZE 512                           // first sector of 512 bytes 

static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent)

{

    BDRVVmdkState *s = bs->opaque;

    char desc[DESC_SIZE];

    uint32_t cid;

    char *p_name, *cid_str; 

    size_t cid_str_size;

    /* the descriptor offset = 0x200 */

    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)

        return 0;

    if (parent) {

        cid_str = "parentCID";

        cid_str_size = sizeof("parentCID");

    } else {

        cid_str = "CID";

        cid_str_size = sizeof("CID");

    }

    if ((p_name = strstr(desc,cid_str)) != 0) {

        p_name += cid_str_size;

        sscanf(p_name,"%x",&cid);

    }

    return cid;

}

static int vmdk_write_cid(BlockDriverState *bs, uint32_t cid)

{

    BDRVVmdkState *s = bs->opaque;

    char desc[DESC_SIZE], tmp_desc[DESC_SIZE];

    char *p_name, *tmp_str;

    /* the descriptor offset = 0x200 */

    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)

        return -1;

    tmp_str = strstr(desc,"parentCID");

    strcpy(tmp_desc, tmp_str);

    if ((p_name = strstr(desc,"CID")) != 0) {

        p_name += sizeof("CID");

        sprintf(p_name,"%x\n",cid);

        strcat(desc,tmp_desc);

    }

    if (bdrv_pwrite(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)

        return -1;

    return 0;

}

static int vmdk_is_cid_valid(BlockDriverState *bs)

{

#ifdef CHECK_CID

    BDRVVmdkState *s = bs->opaque;

    BlockDriverState *p_bs = s->hd->backing_hd;

    uint32_t cur_pcid;

    if (p_bs) {

        cur_pcid = vmdk_read_cid(p_bs,0);

        if (s->parent_cid != cur_pcid)

            // CID not valid

            return 0;

    }

#endif

    // CID valid

    return 1;

}

static int vmdk_snapshot_create(const char *filename, const char *backing_file)

{

    int snp_fd, p_fd;

    uint32_t p_cid;

    char *p_name, *gd_buf, *rgd_buf; 

    const char *real_filename, *temp_str;

    VMDK4Header header;

    uint32_t gde_entries, gd_size;

    int64_t gd_offset, rgd_offset, capacity, gt_size;

    char p_desc[DESC_SIZE], s_desc[DESC_SIZE], hdr[HEADER_SIZE];

    char *desc_template =

    "# Disk DescriptorFile\n"

    "version=1\n"

    "CID=%x\n"

    "parentCID=%x\n"

    "createType=\"monolithicSparse\"\n"

    "parentFileNameHint=\"%s\"\n"

    "\n"

    "# Extent description\n"

    "RW %lu SPARSE \"%s\"\n"

    "\n"

    "# The Disk Data Base \n"

    "#DDB\n"

    "\n";

    snp_fd = open(filename, O_RDWR | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, 0644);

    if (snp_fd < 0)

        return -1;

    p_fd = open(backing_file, O_RDONLY | O_BINARY | O_LARGEFILE);

    if (p_fd < 0) {

        close(snp_fd);

        return -1;

    }

    /* read the header */

    if (lseek(p_fd, 0x0, SEEK_SET) == -1)

        goto fail;

    if (read(p_fd, hdr, HEADER_SIZE) != HEADER_SIZE)

        goto fail;

    /* write the header */

    if (lseek(snp_fd, 0x0, SEEK_SET) == -1)

        goto fail;

    if (write(snp_fd, hdr, HEADER_SIZE) == -1)

        goto fail;

    memset(&header, 0, sizeof(header));

    memcpy(&header,&hdr[4], sizeof(header)); // skip the VMDK4_MAGIC

    ftruncate(snp_fd, header.grain_offset << 9);

    /* the descriptor offset = 0x200 */

    if (lseek(p_fd, 0x200, SEEK_SET) == -1)

        goto fail;

    if (read(p_fd, p_desc, DESC_SIZE) != DESC_SIZE)

        goto fail;

    if ((p_name = strstr(p_desc,"CID")) != 0) {

        p_name += sizeof("CID");

        sscanf(p_name,"%x",&p_cid);

    }

    real_filename = filename;

    if ((temp_str = strrchr(real_filename, '\\')) != NULL)

        real_filename = temp_str + 1;

    if ((temp_str = strrchr(real_filename, '/')) != NULL)

        real_filename = temp_str + 1;

    if ((temp_str = strrchr(real_filename, ':')) != NULL)

        real_filename = temp_str + 1;

    sprintf(s_desc, desc_template, p_cid, p_cid, backing_file

            , (uint32_t)header.capacity, real_filename);

    /* write the descriptor */

    if (lseek(snp_fd, 0x200, SEEK_SET) == -1)

        goto fail;

    if (write(snp_fd, s_desc, strlen(s_desc)) == -1)

        goto fail;

    gd_offset = header.gd_offset * SECTOR_SIZE;     // offset of GD table

    rgd_offset = header.rgd_offset * SECTOR_SIZE;   // offset of RGD table

    capacity = header.capacity * SECTOR_SIZE;       // Extent size

    /*

     * Each GDE span 32M disk, means:

     * 512 GTE per GT, each GTE points to grain

     */

    gt_size = (int64_t)header.num_gtes_per_gte * header.granularity * SECTOR_SIZE;

    if (!gt_size)

        goto fail;

    gde_entries = (uint32_t)(capacity / gt_size);  // number of gde/rgde 

    gd_size = gde_entries * sizeof(uint32_t);

    /* write RGD */

    rgd_buf = qemu_malloc(gd_size);

    if (!rgd_buf)

        goto fail;

    if (lseek(p_fd, rgd_offset, SEEK_SET) == -1)

        goto fail_rgd;

    if (read(p_fd, rgd_buf, gd_size) != gd_size)

        goto fail_rgd;

    if (lseek(snp_fd, rgd_offset, SEEK_SET) == -1)

        goto fail_rgd;

    if (write(snp_fd, rgd_buf, gd_size) == -1)

        goto fail_rgd;

    qemu_free(rgd_buf);

    /* write GD */

    gd_buf = qemu_malloc(gd_size);

    if (!gd_buf)

        goto fail_rgd;

    if (lseek(p_fd, gd_offset, SEEK_SET) == -1)

        goto fail_gd;

    if (read(p_fd, gd_buf, gd_size) != gd_size)

        goto fail_gd;

    if (lseek(snp_fd, gd_offset, SEEK_SET) == -1)

        goto fail_gd;

    if (write(snp_fd, gd_buf, gd_size) == -1)

        goto fail_gd;

    qemu_free(gd_buf);

    close(p_fd);

    close(snp_fd);

    return 0;

    fail_gd:

    qemu_free(gd_buf);

    fail_rgd:   

    qemu_free(rgd_buf);

    fail:

    close(p_fd);

    close(snp_fd);

    return -1;

}

static void vmdk_parent_close(BlockDriverState *bs)

{

    if (bs->backing_hd)

        bdrv_close(bs->backing_hd);

}

int parent_open = 0;

static int vmdk_parent_open(BlockDriverState *bs, const char * filename)

{

    BDRVVmdkState *s = bs->opaque;

    char *p_name; 

    char desc[DESC_SIZE];

    char parent_img_name[1024];

    /* the descriptor offset = 0x200 */

    if (bdrv_pread(s->hd, 0x200, desc, DESC_SIZE) != DESC_SIZE)

        return -1;

    if ((p_name = strstr(desc,"parentFileNameHint")) != 0) {

        char *end_name;

        struct stat file_buf;

        p_name += sizeof("parentFileNameHint") + 1;

        if ((end_name = strchr(p_name,'\"')) == 0)

            return -1;

        strncpy(s->hd->backing_file, p_name, end_name - p_name);

        if (stat(s->hd->backing_file, &file_buf) != 0) {

            path_combine(parent_img_name, sizeof(parent_img_name),

                         filename, s->hd->backing_file);

        } else {

            strcpy(parent_img_name, s->hd->backing_file);

        }

        s->hd->backing_hd = bdrv_new("");

        if (!s->hd->backing_hd) {

            failure:

            bdrv_close(s->hd);

            return -1;

        }

        parent_open = 1;

        if (bdrv_open(s->hd->backing_hd, parent_img_name, BDRV_O_RDONLY) < 0)

            goto failure;

        parent_open = 0;

    }

    return 0;

}

static int vmdk_open(BlockDriverState *bs, const char *filename, int flags)

{

    BDRVVmdkState *s = bs->opaque;

    uint32_t magic;

    int l1_size, i, ret;

    if (parent_open)

        // Parent must be opened as RO.

        flags = BDRV_O_RDONLY;

    fprintf(stderr, "(VMDK) image open: flags=0x%x filename=%s\n", flags, bs->filename);

    ret = bdrv_file_open(&s->hd, filename, flags);

    if (ret < 0)

        return ret;

    if (bdrv_pread(s->hd, 0, &magic, sizeof(magic)) != sizeof(magic))

        goto fail;

    magic = be32_to_cpu(magic);

    if (magic == VMDK3_MAGIC) {

        VMDK3Header header;

        if (bdrv_pread(s->hd, sizeof(magic), &header, sizeof(header)) != sizeof(header))

            goto fail;

        s->cluster_sectors = le32_to_cpu(header.granularity);

        s->l2_size = 1 << 9;

        s->l1_size = 1 << 6;

        bs->total_sectors = le32_to_cpu(header.disk_sectors);

        s->l1_table_offset = le32_to_cpu(header.l1dir_offset) << 9;

        s->l1_backup_table_offset = 0;

        s->l1_entry_sectors = s->l2_size * s->cluster_sectors;

    } else if (magic == VMDK4_MAGIC) {

        VMDK4Header header;

        if (bdrv_pread(s->hd, sizeof(magic), &header, sizeof(header)) != sizeof(header))

            goto fail;

        bs->total_sectors = le64_to_cpu(header.capacity);

        s->cluster_sectors = le64_to_cpu(header.granularity);

        s->l2_size = le32_to_cpu(header.num_gtes_per_gte);

        s->l1_entry_sectors = s->l2_size * s->cluster_sectors;

        if (s->l1_entry_sectors <= 0)

            goto fail;

        s->l1_size = (bs->total_sectors + s->l1_entry_sectors - 1) 

            / s->l1_entry_sectors;

        s->l1_table_offset = le64_to_cpu(header.rgd_offset) << 9;

        s->l1_backup_table_offset = le64_to_cpu(header.gd_offset) << 9;

        if (parent_open)

            s->is_parent = 1;

        else

            s->is_parent = 0;

        // try to open parent images, if exist

        if (vmdk_parent_open(bs, filename) != 0)

            goto fail;

        // write the CID once after the image creation

        s->parent_cid = vmdk_read_cid(bs,1);

    } else {

        goto fail;

    }

    /* read the L1 table */

    l1_size = s->l1_size * sizeof(uint32_t);

    s->l1_table = qemu_malloc(l1_size);

    if (!s->l1_table)

        goto fail;

    if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, l1_size) != l1_size)

        goto fail;

    for(i = 0; i < s->l1_size; i++) {

        le32_to_cpus(&s->l1_table[i]);

    }

    if (s->l1_backup_table_offset) {

        s->l1_backup_table = qemu_malloc(l1_size);

        if (!s->l1_backup_table)

            goto fail;

        if (bdrv_pread(s->hd, s->l1_backup_table_offset, s->l1_backup_table, l1_size) != l1_size)

            goto fail;

        for(i = 0; i < s->l1_size; i++) {

            le32_to_cpus(&s->l1_backup_table[i]);

        }

    }

    s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint32_t));

    if (!s->l2_cache)

        goto fail;

    return 0;

 fail:

    qemu_free(s->l1_backup_table);

    qemu_free(s->l1_table);

    qemu_free(s->l2_cache);

    bdrv_delete(s->hd);

    return -1;

}

static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,

                                   uint64_t offset, int allocate);

static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset,

                             uint64_t offset, int allocate)

{

    uint64_t parent_cluster_offset;

    BDRVVmdkState *s = bs->opaque;

    uint8_t  whole_grain[s->cluster_sectors*512];        // 128 sectors * 512 bytes each = grain size 64KB

    // we will be here if it's first write on non-exist grain(cluster).

    // try to read from parent image, if exist

    if (s->hd->backing_hd) {

        BDRVVmdkState *ps = s->hd->backing_hd->opaque;

        if (!vmdk_is_cid_valid(bs))

            return -1;

        parent_cluster_offset = get_cluster_offset(s->hd->backing_hd, NULL, offset, allocate);

        if (parent_cluster_offset) {

            BDRVVmdkState *act_s = activeBDRV.hd->opaque;

            if (bdrv_pread(ps->hd, parent_cluster_offset, whole_grain, ps->cluster_sectors*512) != ps->cluster_sectors*512)

                return -1;

            //Write grain only into the active image

            if (bdrv_pwrite(act_s->hd, activeBDRV.cluster_offset << 9, whole_grain, sizeof(whole_grain)) != sizeof(whole_grain))

                return -1;

        }

    }

    return 0;

}

static int vmdk_L2update(BlockDriverState *bs, VmdkMetaData *m_data)

{

    BDRVVmdkState *s = bs->opaque;

    /* update L2 table */

    if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),

                    &(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))

        return -1;

    /* update backup L2 table */

    if (s->l1_backup_table_offset != 0) {

        m_data->l2_offset = s->l1_backup_table[m_data->l1_index];

        if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),

                        &(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))

            return -1;

    }

    return 0;

}

static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,

                                   uint64_t offset, int allocate)

{

    BDRVVmdkState *s = bs->opaque;

    unsigned int l1_index, l2_offset, l2_index;

    int min_index, i, j;

    uint32_t min_count, *l2_table, tmp = 0;

    uint64_t cluster_offset;

    int status;

    if (m_data)

        m_data->valid = 0;

    l1_index = (offset >> 9) / s->l1_entry_sectors;

    if (l1_index >= s->l1_size)

        return 0;

    l2_offset = s->l1_table[l1_index];

    if (!l2_offset)

        return 0;

    for(i = 0; i < L2_CACHE_SIZE; i++) {

        if (l2_offset == s->l2_cache_offsets[i]) {

            /* increment the hit count */

            if (++s->l2_cache_counts[i] == 0xffffffff) {

                for(j = 0; j < L2_CACHE_SIZE; j++) {

                    s->l2_cache_counts[j] >>= 1;

                }

            }

            l2_table = s->l2_cache + (i * s->l2_size);

            goto found;

        }

    }

    /* not found: load a new entry in the least used one */

    min_index = 0;

    min_count = 0xffffffff;

    for(i = 0; i < L2_CACHE_SIZE; i++) {

        if (s->l2_cache_counts[i] < min_count) {

            min_count = s->l2_cache_counts[i];

            min_index = i;

        }

    }

    l2_table = s->l2_cache + (min_index * s->l2_size);

    if (bdrv_pread(s->hd, (int64_t)l2_offset * 512, l2_table, s->l2_size * sizeof(uint32_t)) != 

                                                                        s->l2_size * sizeof(uint32_t))

        return 0;

    s->l2_cache_offsets[min_index] = l2_offset;

    s->l2_cache_counts[min_index] = 1;

 found:

    l2_index = ((offset >> 9) / s->cluster_sectors) % s->l2_size;

    cluster_offset = le32_to_cpu(l2_table[l2_index]);

    if (!cluster_offset) {

        struct stat file_buf;

        if (!allocate)

            return 0;

        // Avoid the L2 tables update for the images that have snapshots.

        if (!s->is_parent) {

            status = stat(s->hd->filename, &file_buf);

            if (status == -1) {

                fprintf(stderr, "(VMDK) Fail file stat: filename =%s size=0x%llx errno=%s\n",

                                s->hd->filename, (uint64_t)file_buf.st_size, strerror(errno));

                return 0;

            }

            cluster_offset = file_buf.st_size;

            bdrv_truncate(s->hd, cluster_offset + (s->cluster_sectors << 9));

            cluster_offset >>= 9;

            tmp = cpu_to_le32(cluster_offset);

            l2_table[l2_index] = tmp;

            // Save the active image state

            activeBDRV.cluster_offset = cluster_offset;

            activeBDRV.hd = bs;

        }

        /* First of all we write grain itself, to avoid race condition

         * that may to corrupt the image.

         * This problem may occur because of insufficient space on host disk

         * or inappropriate VM shutdown.

         */

        if (get_whole_cluster(bs, cluster_offset, offset, allocate) == -1)

            return 0;

        if (m_data) {

            m_data->offset = tmp;

            m_data->l1_index = l1_index;

            m_data->l2_index = l2_index;

            m_data->l2_offset = l2_offset;

            m_data->valid = 1;

        }

    }

    cluster_offset <<= 9;

    return cluster_offset;

}

static int vmdk_is_allocated(BlockDriverState *bs, int64_t sector_num, 

                             int nb_sectors, int *pnum)

{

    BDRVVmdkState *s = bs->opaque;

    int index_in_cluster, n;

    uint64_t cluster_offset;

    cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);

    index_in_cluster = sector_num % s->cluster_sectors;

    n = s->cluster_sectors - index_in_cluster;

    if (n > nb_sectors)

        n = nb_sectors;

    *pnum = n;

    return (cluster_offset != 0);

}

static int vmdk_read(BlockDriverState *bs, int64_t sector_num, 

                    uint8_t *buf, int nb_sectors)

{

    BDRVVmdkState *s = bs->opaque;

    int index_in_cluster, n, ret;

    uint64_t cluster_offset;

    while (nb_sectors > 0) {

        cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);

        index_in_cluster = sector_num % s->cluster_sectors;

        n = s->cluster_sectors - index_in_cluster;

        if (n > nb_sectors)

            n = nb_sectors;

        if (!cluster_offset) {

            // try to read from parent image, if exist

            if (s->hd->backing_hd) {

                if (!vmdk_is_cid_valid(bs))

                    return -1;

                ret = bdrv_read(s->hd->backing_hd, sector_num, buf, n);

                if (ret < 0)

                    return -1;

            } else {

                memset(buf, 0, 512 * n);

            }

        } else {

            if(bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)

                return -1;

        }

        nb_sectors -= n;

        sector_num += n;

        buf += n * 512;

    }

    return 0;

}

static int vmdk_write(BlockDriverState *bs, int64_t sector_num, 

                     const uint8_t *buf, int nb_sectors)

{

    BDRVVmdkState *s = bs->opaque;

    VmdkMetaData m_data;

    int index_in_cluster, n;

    uint64_t cluster_offset;

    static int cid_update = 0;

    if (sector_num > bs->total_sectors) {

        fprintf(stderr,

                "(VMDK) Wrong offset: sector_num=0x%llx total_sectors=0x%llx\n",

                sector_num, bs->total_sectors);

        return -1;

    }

    while (nb_sectors > 0) {

        index_in_cluster = sector_num & (s->cluster_sectors - 1);

        n = s->cluster_sectors - index_in_cluster;

        if (n > nb_sectors)

            n = nb_sectors;

        cluster_offset = get_cluster_offset(bs, &m_data, sector_num << 9, 1);

        if (!cluster_offset)

            return -1;

        if (bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)

            return -1;

        if (m_data.valid) {

            /* update L2 tables */

            if (vmdk_L2update(bs, &m_data) == -1)

                return -1;

        }

        nb_sectors -= n;

        sector_num += n;

        buf += n * 512;

        // update CID on the first write every time the virtual disk is opened

        if (!cid_update) {

            vmdk_write_cid(bs, time(NULL));

            cid_update++;

        }

    }

    return 0;

}

static int vmdk_create(const char *filename, int64_t total_size,

                       const char *backing_file, int flags)

{

    int fd, i;

    VMDK4Header header;

    uint32_t tmp, magic, grains, gd_size, gt_size, gt_count;

    char *desc_template =

        "# Disk DescriptorFile\n"

        "version=1\n"

        "CID=%x\n"

        "parentCID=ffffffff\n"

        "createType=\"monolithicSparse\"\n"

        "\n"

        "# Extent description\n"

        "RW %lu SPARSE \"%s\"\n"

        "\n"

        "# The Disk Data Base \n"

        "#DDB\n"

        "\n"

        "ddb.virtualHWVersion = \"4\"\n"

        "ddb.geometry.cylinders = \"%lu\"\n"

        "ddb.geometry.heads = \"16\"\n"

        "ddb.geometry.sectors = \"63\"\n"

        "ddb.adapterType = \"ide\"\n";

    char desc[1024];

    const char *real_filename, *temp_str;

    /* XXX: add support for backing file */

    if (backing_file) {

        return vmdk_snapshot_create(filename, backing_file);

    }

    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,

              0644);

    if (fd < 0)

        return -1;

    magic = cpu_to_be32(VMDK4_MAGIC);

    memset(&header, 0, sizeof(header));

    header.version = cpu_to_le32(1);

    header.flags = cpu_to_le32(3); /* ?? */

    header.capacity = cpu_to_le64(total_size);

    header.granularity = cpu_to_le64(128);

    header.num_gtes_per_gte = cpu_to_le32(512);

    grains = (total_size + header.granularity - 1) / header.granularity;

    gt_size = ((header.num_gtes_per_gte * sizeof(uint32_t)) + 511) >> 9;

    gt_count = (grains + header.num_gtes_per_gte - 1) / header.num_gtes_per_gte;

    gd_size = (gt_count * sizeof(uint32_t) + 511) >> 9;

    header.desc_offset = 1;

    header.desc_size = 20;

    header.rgd_offset = header.desc_offset + header.desc_size;

    header.gd_offset = header.rgd_offset + gd_size + (gt_size * gt_count);

    header.grain_offset =

       ((header.gd_offset + gd_size + (gt_size * gt_count) +

         header.granularity - 1) / header.granularity) *

        header.granularity;

    header.desc_offset = cpu_to_le64(header.desc_offset);

    header.desc_size = cpu_to_le64(header.desc_size);

    header.rgd_offset = cpu_to_le64(header.rgd_offset);

    header.gd_offset = cpu_to_le64(header.gd_offset);

    header.grain_offset = cpu_to_le64(header.grain_offset);

    header.check_bytes[0] = 0xa;

    header.check_bytes[1] = 0x20;

    header.check_bytes[2] = 0xd;

    header.check_bytes[3] = 0xa;

    /* write all the data */    

    write(fd, &magic, sizeof(magic));

    write(fd, &header, sizeof(header));

    ftruncate(fd, header.grain_offset << 9);

    /* write grain directory */

    lseek(fd, le64_to_cpu(header.rgd_offset) << 9, SEEK_SET);

    for (i = 0, tmp = header.rgd_offset + gd_size;

         i < gt_count; i++, tmp += gt_size)

        write(fd, &tmp, sizeof(tmp));

    /* write backup grain directory */

    lseek(fd, le64_to_cpu(header.gd_offset) << 9, SEEK_SET);

    for (i = 0, tmp = header.gd_offset + gd_size;

         i < gt_count; i++, tmp += gt_size)

        write(fd, &tmp, sizeof(tmp));

    /* compose the descriptor */

    real_filename = filename;

    if ((temp_str = strrchr(real_filename, '\\')) != NULL)

        real_filename = temp_str + 1;

    if ((temp_str = strrchr(real_filename, '/')) != NULL)

        real_filename = temp_str + 1;

    if ((temp_str = strrchr(real_filename, ':')) != NULL)

        real_filename = temp_str + 1;

    sprintf(desc, desc_template, time(NULL), (unsigned long)total_size,

            real_filename, total_size / (63 * 16));

    /* write the descriptor */

    lseek(fd, le64_to_cpu(header.desc_offset) << 9, SEEK_SET);

    write(fd, desc, strlen(desc));

    close(fd);

    return 0;

}

static void vmdk_close(BlockDriverState *bs)

{

    BDRVVmdkState *s = bs->opaque;

    qemu_free(s->l1_table);

    qemu_free(s->l2_cache);

    bdrv_delete(s->hd);

    // try to close parent image, if exist

    vmdk_parent_close(s->hd);

}

static void vmdk_flush(BlockDriverState *bs)

{

    BDRVVmdkState *s = bs->opaque;

    bdrv_flush(s->hd);

}

BlockDriver bdrv_vmdk = {

    "vmdk",

    sizeof(BDRVVmdkState),

    vmdk_probe,

    vmdk_open,

    vmdk_read,

    vmdk_write,

    vmdk_close,

    vmdk_create,

    vmdk_flush,

    vmdk_is_allocated,

};