block-raw.c

qemu性能直逼VMware的仿真器QEMU 的模擬速度約為實機的 25％；約為 Bochs 的 60 倍。Plex86、User-Mode-Linux、VMware 和 Virtual PC 則比

    }
    if (flags & BDRV_O_CREAT) {
        create_flags = CREATE_ALWAYS;
    } else {
        create_flags = OPEN_EXISTING;
    }
#ifdef QEMU_TOOL
    overlapped = FILE_ATTRIBUTE_NORMAL;
#else
    overlapped = FILE_FLAG_OVERLAPPED;
#endif
    s->hfile = CreateFile(filename, access_flags, 
                          FILE_SHARE_READ, NULL,
                          create_flags, overlapped, NULL);
    if (s->hfile == INVALID_HANDLE_VALUE) {
        int err = GetLastError();

        if (err == ERROR_ACCESS_DENIED)
            return -EACCES;
        return -1;
    }
    return 0;
}

static int raw_pread(BlockDriverState *bs, int64_t offset, 
                     uint8_t *buf, int count)
{
    BDRVRawState *s = bs->opaque;
    OVERLAPPED ov;
    DWORD ret_count;
    int ret;
    
    memset(&ov, 0, sizeof(ov));
    ov.Offset = offset;
    ov.OffsetHigh = offset >> 32;
    ret = ReadFile(s->hfile, buf, count, &ret_count, &ov);
    if (!ret) {
        ret = GetOverlappedResult(s->hfile, &ov, &ret_count, TRUE);
        if (!ret)
            return -EIO;
        else
            return ret_count;
    }
    return ret_count;
}

static int raw_pwrite(BlockDriverState *bs, int64_t offset, 
                      const uint8_t *buf, int count)
{
    BDRVRawState *s = bs->opaque;
    OVERLAPPED ov;
    DWORD ret_count;
    int ret;
    
    memset(&ov, 0, sizeof(ov));
    ov.Offset = offset;
    ov.OffsetHigh = offset >> 32;
    ret = WriteFile(s->hfile, buf, count, &ret_count, &ov);
    if (!ret) {
        ret = GetOverlappedResult(s->hfile, &ov, &ret_count, TRUE);
        if (!ret)
            return -EIO;
        else
            return ret_count;
    }
    return ret_count;
}

#if 0
#ifndef QEMU_TOOL
static void raw_aio_cb(void *opaque)
{
    RawAIOCB *acb = opaque;
    BlockDriverState *bs = acb->common.bs;
    BDRVRawState *s = bs->opaque;
    DWORD ret_count;
    int ret;

    ret = GetOverlappedResult(s->hfile, &acb->ov, &ret_count, TRUE);
    if (!ret || ret_count != acb->count) {
        acb->common.cb(acb->common.opaque, -EIO);
    } else {
        acb->common.cb(acb->common.opaque, 0);
    }
}
#endif

static RawAIOCB *raw_aio_setup(BlockDriverState *bs,
        int64_t sector_num, uint8_t *buf, int nb_sectors,
        BlockDriverCompletionFunc *cb, void *opaque)
{
    RawAIOCB *acb;
    int64_t offset;

    acb = qemu_aio_get(bs, cb, opaque);
    if (acb->hEvent) {
        acb->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
        if (!acb->hEvent) {
            qemu_aio_release(acb);
            return NULL;
        }
    }
    memset(&acb->ov, 0, sizeof(acb->ov));
    offset = sector_num * 512;
    acb->ov.Offset = offset;
    acb->ov.OffsetHigh = offset >> 32;
    acb->ov.hEvent = acb->hEvent;
    acb->count = nb_sectors * 512;
#ifndef QEMU_TOOL
    qemu_add_wait_object(acb->ov.hEvent, raw_aio_cb, acb);
#endif
    return acb;
}

static BlockDriverAIOCB *raw_aio_read(BlockDriverState *bs,
        int64_t sector_num, uint8_t *buf, int nb_sectors,
        BlockDriverCompletionFunc *cb, void *opaque)
{
    BDRVRawState *s = bs->opaque;
    RawAIOCB *acb;
    int ret;

    acb = raw_aio_setup(bs, sector_num, buf, nb_sectors, cb, opaque);
    if (!acb)
        return NULL;
    ret = ReadFile(s->hfile, buf, acb->count, NULL, &acb->ov);
    if (!ret) {
        qemu_aio_release(acb);
        return NULL;
    }
#ifdef QEMU_TOOL
    qemu_aio_release(acb);
#endif
    return (BlockDriverAIOCB *)acb;
}

static BlockDriverAIOCB *raw_aio_write(BlockDriverState *bs,
        int64_t sector_num, uint8_t *buf, int nb_sectors,
        BlockDriverCompletionFunc *cb, void *opaque)
{
    BDRVRawState *s = bs->opaque;
    RawAIOCB *acb;
    int ret;

    acb = raw_aio_setup(bs, sector_num, buf, nb_sectors, cb, opaque);
    if (!acb)
        return NULL;
    ret = WriteFile(s->hfile, buf, acb->count, NULL, &acb->ov);
    if (!ret) {
        qemu_aio_release(acb);
        return NULL;
    }
#ifdef QEMU_TOOL
    qemu_aio_release(acb);
#endif
    return (BlockDriverAIOCB *)acb;
}

static void raw_aio_cancel(BlockDriverAIOCB *blockacb)
{
#ifndef QEMU_TOOL
    RawAIOCB *acb = (RawAIOCB *)blockacb;
    BlockDriverState *bs = acb->common.bs;
    BDRVRawState *s = bs->opaque;

    qemu_del_wait_object(acb->ov.hEvent, raw_aio_cb, acb);
    /* XXX: if more than one async I/O it is not correct */
    CancelIo(s->hfile);
    qemu_aio_release(acb);
#endif
}
#endif /* #if 0 */

static void raw_flush(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    FlushFileBuffers(s->hfile);
}

static void raw_close(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    CloseHandle(s->hfile);
}

static int raw_truncate(BlockDriverState *bs, int64_t offset)
{
    BDRVRawState *s = bs->opaque;
    DWORD low, high;

    low = offset;
    high = offset >> 32;
    if (!SetFilePointer(s->hfile, low, &high, FILE_BEGIN))
	return -EIO;
    if (!SetEndOfFile(s->hfile))
        return -EIO;
    return 0;
}

static int64_t raw_getlength(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    LARGE_INTEGER l;
    ULARGE_INTEGER available, total, total_free; 
    DISK_GEOMETRY dg;
    DWORD count;
    BOOL status;

    switch(s->type) {
    case FTYPE_FILE:
        l.LowPart = GetFileSize(s->hfile, &l.HighPart);
        if (l.LowPart == 0xffffffffUL && GetLastError() != NO_ERROR)
            return -EIO;
        break;
    case FTYPE_CD:
        if (!GetDiskFreeSpaceEx(s->drive_path, &available, &total, &total_free))
            return -EIO;
        l.QuadPart = total.QuadPart;
        break;
    case FTYPE_HARDDISK:
        status = DeviceIoControl(s->hfile, IOCTL_DISK_GET_DRIVE_GEOMETRY,
                                 NULL, 0, &dg, sizeof(dg), &count, NULL);
        if (status != FALSE) {
            l.QuadPart = dg.Cylinders.QuadPart * dg.TracksPerCylinder
                * dg.SectorsPerTrack * dg.BytesPerSector;
        }
        break;
    default:
        return -EIO;
    }
    return l.QuadPart;
}

static int raw_create(const char *filename, int64_t total_size,
                      const char *backing_file, int flags)
{
    int fd;

    if (flags || backing_file)
        return -ENOTSUP;

    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 
              0644);
    if (fd < 0)
        return -EIO;
    set_sparse(fd);
    ftruncate(fd, total_size * 512);
    close(fd);
    return 0;
}

void qemu_aio_init(void)
{
}

void qemu_aio_poll(void)
{
}

void qemu_aio_flush(void)
{
}

void qemu_aio_wait_start(void)
{
}

void qemu_aio_wait(void)
{
#ifndef QEMU_TOOL
    qemu_bh_poll();
#endif
}

void qemu_aio_wait_end(void)
{
}

BlockDriver bdrv_raw = {
    "raw",
    sizeof(BDRVRawState),
    NULL, /* no probe for protocols */
    raw_open,
    NULL,
    NULL,
    raw_close,
    raw_create,
    raw_flush,
    
#if 0
    .bdrv_aio_read = raw_aio_read,
    .bdrv_aio_write = raw_aio_write,
    .bdrv_aio_cancel = raw_aio_cancel,
    .aiocb_size = sizeof(RawAIOCB);
#endif
    .protocol_name = "file",
    .bdrv_pread = raw_pread,
    .bdrv_pwrite = raw_pwrite,
    .bdrv_truncate = raw_truncate,
    .bdrv_getlength = raw_getlength,
};

/***********************************************/
/* host device */

static int find_cdrom(char *cdrom_name, int cdrom_name_size)
{
    char drives[256], *pdrv = drives;
    UINT type;

    memset(drives, 0, sizeof(drives));
    GetLogicalDriveStrings(sizeof(drives), drives);
    while(pdrv[0] != '\0') {
        type = GetDriveType(pdrv);
        switch(type) {
        case DRIVE_CDROM:
            snprintf(cdrom_name, cdrom_name_size, "\\\\.\\%c:", pdrv[0]);
            return 0;
            break;
        }
        pdrv += lstrlen(pdrv) + 1;
    }
    return -1;
}

static int find_device_type(BlockDriverState *bs, const char *filename)
{
    BDRVRawState *s = bs->opaque;
    UINT type;
    const char *p;

    if (strstart(filename, "\\\\.\\", &p) ||
        strstart(filename, "//./", &p)) {
        if (stristart(p, "PhysicalDrive", NULL))
            return FTYPE_HARDDISK;
        snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\", p[0]);
        type = GetDriveType(s->drive_path);
        if (type == DRIVE_CDROM)
            return FTYPE_CD;
        else
            return FTYPE_FILE;
    } else {
        return FTYPE_FILE;
    }
}

static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
{
    BDRVRawState *s = bs->opaque;
    int access_flags, create_flags;
    DWORD overlapped;
    char device_name[64];

    if (strstart(filename, "/dev/cdrom", NULL)) {
        if (find_cdrom(device_name, sizeof(device_name)) < 0)
            return -ENOENT;
        filename = device_name;
    } else {
        /* transform drive letters into device name */
        if (((filename[0] >= 'a' && filename[0] <= 'z') ||
             (filename[0] >= 'A' && filename[0] <= 'Z')) &&
            filename[1] == ':' && filename[2] == '\0') {
            snprintf(device_name, sizeof(device_name), "\\\\.\\%c:", filename[0]);
            filename = device_name;
        }
    }
    s->type = find_device_type(bs, filename);
    
    if ((flags & BDRV_O_ACCESS) == O_RDWR) {
        access_flags = GENERIC_READ | GENERIC_WRITE;
    } else {
        access_flags = GENERIC_READ;
    }
    create_flags = OPEN_EXISTING;

#ifdef QEMU_TOOL
    overlapped = FILE_ATTRIBUTE_NORMAL;
#else
    overlapped = FILE_FLAG_OVERLAPPED;
#endif
    s->hfile = CreateFile(filename, access_flags, 
                          FILE_SHARE_READ, NULL,
                          create_flags, overlapped, NULL);
    if (s->hfile == INVALID_HANDLE_VALUE) {
        int err = GetLastError();

        if (err == ERROR_ACCESS_DENIED)
            return -EACCES;
        return -1;
    }
    return 0;
}

#if 0
/***********************************************/
/* removable device additionnal commands */

static int raw_is_inserted(BlockDriverState *bs)
{
    return 1;
}

static int raw_media_changed(BlockDriverState *bs)
{
    return -ENOTSUP;
}

static int raw_eject(BlockDriverState *bs, int eject_flag)
{
    DWORD ret_count;

    if (s->type == FTYPE_FILE)
        return -ENOTSUP;
    if (eject_flag) {
        DeviceIoControl(s->hfile, IOCTL_STORAGE_EJECT_MEDIA, 
                        NULL, 0, NULL, 0, &lpBytesReturned, NULL);
    } else {
        DeviceIoControl(s->hfile, IOCTL_STORAGE_LOAD_MEDIA, 
                        NULL, 0, NULL, 0, &lpBytesReturned, NULL);
    }
}

static int raw_set_locked(BlockDriverState *bs, int locked)
{
    return -ENOTSUP;
}
#endif

BlockDriver bdrv_host_device = {
    "host_device",
    sizeof(BDRVRawState),
    NULL, /* no probe for protocols */
    hdev_open,
    NULL,
    NULL,
    raw_close,
    NULL,
    raw_flush,
    
#if 0
    .bdrv_aio_read = raw_aio_read,
    .bdrv_aio_write = raw_aio_write,
    .bdrv_aio_cancel = raw_aio_cancel,
    .aiocb_size = sizeof(RawAIOCB);
#endif
    .bdrv_pread = raw_pread,
    .bdrv_pwrite = raw_pwrite,
    .bdrv_getlength = raw_getlength,
};
#endif /* _WIN32 */