block-qcow2.c.svn-base

我们自己开发的一个OSEK操作系统！不知道可不可以？

            qemu_free(out_buf);
            return -1;
        }
    }

    qemu_free(out_buf);
    return 0;
}

static void qcow_flush(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    bdrv_flush(s->hd);
}

static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
    BDRVQcowState *s = bs->opaque;
    bdi->cluster_size = s->cluster_size;
    bdi->vm_state_offset = (int64_t)s->l1_vm_state_index <<
        (s->cluster_bits + s->l2_bits);
    return 0;
}

/*********************************************************/
/* snapshot support */

/* update the refcounts of snapshots and the copied flag */
static int update_snapshot_refcount(BlockDriverState *bs,
                                    int64_t l1_table_offset,
                                    int l1_size,
                                    int addend)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
    int64_t old_offset, old_l2_offset;
    int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount;

    l2_cache_reset(bs);

    l2_table = NULL;
    l1_table = NULL;
    l1_size2 = l1_size * sizeof(uint64_t);
    l1_allocated = 0;
    if (l1_table_offset != s->l1_table_offset) {
        l1_table = qemu_malloc(l1_size2);
        if (!l1_table)
            goto fail;
        l1_allocated = 1;
        if (bdrv_pread(s->hd, l1_table_offset,
                       l1_table, l1_size2) != l1_size2)
            goto fail;
        for(i = 0;i < l1_size; i++)
            be64_to_cpus(&l1_table[i]);
    } else {
        assert(l1_size == s->l1_size);
        l1_table = s->l1_table;
        l1_allocated = 0;
    }

    l2_size = s->l2_size * sizeof(uint64_t);
    l2_table = qemu_malloc(l2_size);
    if (!l2_table)
        goto fail;
    l1_modified = 0;
    for(i = 0; i < l1_size; i++) {
        l2_offset = l1_table[i];
        if (l2_offset) {
            old_l2_offset = l2_offset;
            l2_offset &= ~QCOW_OFLAG_COPIED;
            l2_modified = 0;
            if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
                goto fail;
            for(j = 0; j < s->l2_size; j++) {
                offset = be64_to_cpu(l2_table[j]);
                if (offset != 0) {
                    old_offset = offset;
                    offset &= ~QCOW_OFLAG_COPIED;
                    if (offset & QCOW_OFLAG_COMPRESSED) {
                        nb_csectors = ((offset >> s->csize_shift) &
                                       s->csize_mask) + 1;
                        if (addend != 0)
                            update_refcount(bs, (offset & s->cluster_offset_mask) & ~511,
                                            nb_csectors * 512, addend);
                        /* compressed clusters are never modified */
                        refcount = 2;
                    } else {
                        if (addend != 0) {
                            refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend);
                        } else {
                            refcount = get_refcount(bs, offset >> s->cluster_bits);
                        }
                    }

                    if (refcount == 1) {
                        offset |= QCOW_OFLAG_COPIED;
                    }
                    if (offset != old_offset) {
                        l2_table[j] = cpu_to_be64(offset);
                        l2_modified = 1;
                    }
                }
            }
            if (l2_modified) {
                if (bdrv_pwrite(s->hd,
                                l2_offset, l2_table, l2_size) != l2_size)
                    goto fail;
            }

            if (addend != 0) {
                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
            } else {
                refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
            }
            if (refcount == 1) {
                l2_offset |= QCOW_OFLAG_COPIED;
            }
            if (l2_offset != old_l2_offset) {
                l1_table[i] = l2_offset;
                l1_modified = 1;
            }
        }
    }
    if (l1_modified) {
        for(i = 0; i < l1_size; i++)
            cpu_to_be64s(&l1_table[i]);
        if (bdrv_pwrite(s->hd, l1_table_offset, l1_table,
                        l1_size2) != l1_size2)
            goto fail;
        for(i = 0; i < l1_size; i++)
            be64_to_cpus(&l1_table[i]);
    }
    if (l1_allocated)
        qemu_free(l1_table);
    qemu_free(l2_table);
    return 0;
 fail:
    if (l1_allocated)
        qemu_free(l1_table);
    qemu_free(l2_table);
    return -EIO;
}

static void qcow_free_snapshots(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    int i;

    for(i = 0; i < s->nb_snapshots; i++) {
        qemu_free(s->snapshots[i].name);
        qemu_free(s->snapshots[i].id_str);
    }
    qemu_free(s->snapshots);
    s->snapshots = NULL;
    s->nb_snapshots = 0;
}

static int qcow_read_snapshots(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshotHeader h;
    QCowSnapshot *sn;
    int i, id_str_size, name_size;
    int64_t offset;
    uint32_t extra_data_size;

    offset = s->snapshots_offset;
    s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
    if (!s->snapshots)
        goto fail;
    for(i = 0; i < s->nb_snapshots; i++) {
        offset = align_offset(offset, 8);
        if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h))
            goto fail;
        offset += sizeof(h);
        sn = s->snapshots + i;
        sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
        sn->l1_size = be32_to_cpu(h.l1_size);
        sn->vm_state_size = be32_to_cpu(h.vm_state_size);
        sn->date_sec = be32_to_cpu(h.date_sec);
        sn->date_nsec = be32_to_cpu(h.date_nsec);
        sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
        extra_data_size = be32_to_cpu(h.extra_data_size);

        id_str_size = be16_to_cpu(h.id_str_size);
        name_size = be16_to_cpu(h.name_size);

        offset += extra_data_size;

        sn->id_str = qemu_malloc(id_str_size + 1);
        if (!sn->id_str)
            goto fail;
        if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
            goto fail;
        offset += id_str_size;
        sn->id_str[id_str_size] = '\0';

        sn->name = qemu_malloc(name_size + 1);
        if (!sn->name)
            goto fail;
        if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
            goto fail;
        offset += name_size;
        sn->name[name_size] = '\0';
    }
    s->snapshots_size = offset - s->snapshots_offset;
    return 0;
 fail:
    qcow_free_snapshots(bs);
    return -1;
}

/* add at the end of the file a new list of snapshots */
static int qcow_write_snapshots(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshot *sn;
    QCowSnapshotHeader h;
    int i, name_size, id_str_size, snapshots_size;
    uint64_t data64;
    uint32_t data32;
    int64_t offset, snapshots_offset;

    /* compute the size of the snapshots */
    offset = 0;
    for(i = 0; i < s->nb_snapshots; i++) {
        sn = s->snapshots + i;
        offset = align_offset(offset, 8);
        offset += sizeof(h);
        offset += strlen(sn->id_str);
        offset += strlen(sn->name);
    }
    snapshots_size = offset;

    snapshots_offset = alloc_clusters(bs, snapshots_size);
    offset = snapshots_offset;

    for(i = 0; i < s->nb_snapshots; i++) {
        sn = s->snapshots + i;
        memset(&h, 0, sizeof(h));
        h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
        h.l1_size = cpu_to_be32(sn->l1_size);
        h.vm_state_size = cpu_to_be32(sn->vm_state_size);
        h.date_sec = cpu_to_be32(sn->date_sec);
        h.date_nsec = cpu_to_be32(sn->date_nsec);
        h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);

        id_str_size = strlen(sn->id_str);
        name_size = strlen(sn->name);
        h.id_str_size = cpu_to_be16(id_str_size);
        h.name_size = cpu_to_be16(name_size);
        offset = align_offset(offset, 8);
        if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
            goto fail;
        offset += sizeof(h);
        if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
            goto fail;
        offset += id_str_size;
        if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
            goto fail;
        offset += name_size;
    }

    /* update the various header fields */
    data64 = cpu_to_be64(snapshots_offset);
    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
                    &data64, sizeof(data64)) != sizeof(data64))
        goto fail;
    data32 = cpu_to_be32(s->nb_snapshots);
    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
                    &data32, sizeof(data32)) != sizeof(data32))
        goto fail;

    /* free the old snapshot table */
    free_clusters(bs, s->snapshots_offset, s->snapshots_size);
    s->snapshots_offset = snapshots_offset;
    s->snapshots_size = snapshots_size;
    return 0;
 fail:
    return -1;
}

static void find_new_snapshot_id(BlockDriverState *bs,
                                 char *id_str, int id_str_size)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshot *sn;
    int i, id, id_max = 0;

    for(i = 0; i < s->nb_snapshots; i++) {
        sn = s->snapshots + i;
        id = strtoul(sn->id_str, NULL, 10);
        if (id > id_max)
            id_max = id;
    }
    snprintf(id_str, id_str_size, "%d", id_max + 1);
}

static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
{
    BDRVQcowState *s = bs->opaque;
    int i;

    for(i = 0; i < s->nb_snapshots; i++) {
        if (!strcmp(s->snapshots[i].id_str, id_str))
            return i;
    }
    return -1;
}

static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
{
    BDRVQcowState *s = bs->opaque;
    int i, ret;

    ret = find_snapshot_by_id(bs, name);
    if (ret >= 0)
        return ret;
    for(i = 0; i < s->nb_snapshots; i++) {
        if (!strcmp(s->snapshots[i].name, name))
            return i;
    }
    return -1;
}

/* if no id is provided, a new one is constructed */
static int qcow_snapshot_create(BlockDriverState *bs,
                                QEMUSnapshotInfo *sn_info)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshot *snapshots1, sn1, *sn = &sn1;
    int i, ret;
    uint64_t *l1_table = NULL;

    memset(sn, 0, sizeof(*sn));

    if (sn_info->id_str[0] == '\0') {
        /* compute a new id */
        find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
    }

    /* check that the ID is unique */
    if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
        return -ENOENT;

    sn->id_str = qemu_strdup(sn_info->id_str);
    if (!sn->id_str)
        goto fail;
    sn->name = qemu_strdup(sn_info->name);
    if (!sn->name)
        goto fail;
    sn->vm_state_size = sn_info->vm_state_size;
    sn->date_sec = sn_info->date_sec;
    sn->date_nsec = sn_info->date_nsec;
    sn->vm_clock_nsec = sn_info->vm_clock_nsec;

    ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
    if (ret < 0)
        goto fail;

    /* create the L1 table of the snapshot */
    sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
    sn->l1_size = s->l1_size;

    l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
    if (!l1_table)
        goto fail;
    for(i = 0; i < s->l1_size; i++) {
        l1_table[i] = cpu_to_be64(s->l1_table[i]);
    }
    if (bdrv_pwrite(s->hd, sn->l1_table_offset,
                    l1_table, s->l1_size * sizeof(uint64_t)) !=
        (s->l1_size * sizeof(uint64_t)))
        goto fail;
    qemu_free(l1_table);
    l1_table = NULL;

    snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
    if (!snapshots1)
        goto fail;
    memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
    s->snapshots = snapshots1;
    s->snapshots[s->nb_snapshots++] = *sn;

    if (qcow_write_snapshots(bs) < 0)
        goto fail;
#ifdef DEBUG_ALLOC
    check_refcounts(bs);
#endif
    return 0;
 fail:
    qemu_free(sn->name);
    qemu_free(l1_table);
    return -1;
}

/* copy the snapshot 'snapshot_name' into the current disk image */
static int qcow_snapshot_goto(BlockDriverState *bs,
                              const char *snapshot_id)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshot *sn;
    int i, snapshot_index, l1_size2;

    snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
    if (snapshot_index < 0)
        return -ENOENT;