block.c

qemu虚拟机代码

                }
                i++;
	    }
	} else {
            i += n;
        }
    }

    if (bs->drv->bdrv_make_empty)
	return bs->drv->bdrv_make_empty(bs);

    return 0;
}

/* return -1 if error */
int bdrv_read(BlockDriverState *bs, int64_t sector_num, 
              uint8_t *buf, int nb_sectors)
{
    int ret, n;
    BlockDriver *drv = bs->drv;

    if (!bs->inserted)
        return -1;

    while (nb_sectors > 0) {
        if (sector_num == 0 && bs->boot_sector_enabled) {
            memcpy(buf, bs->boot_sector_data, 512);
            n = 1;
        } else if (bs->backing_hd) {
            if (drv->bdrv_is_allocated(bs, sector_num, nb_sectors, &n)) {
                ret = drv->bdrv_read(bs, sector_num, buf, n);
                if (ret < 0)
                    return -1;
            } else {
                /* read from the base image */
                ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
                if (ret < 0)
                    return -1;
            }
        } else {
            ret = drv->bdrv_read(bs, sector_num, buf, nb_sectors);
            if (ret < 0)
                return -1;
            /* no need to loop */
            break;
        }
        nb_sectors -= n;
        sector_num += n;
        buf += n * 512;
    }
    return 0;
}

/* return -1 if error */
int bdrv_write(BlockDriverState *bs, int64_t sector_num, 
               const uint8_t *buf, int nb_sectors)
{
    if (!bs->inserted)
        return -1;
    if (bs->read_only)
        return -1;
    if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {
        memcpy(bs->boot_sector_data, buf, 512);   
    }
    return bs->drv->bdrv_write(bs, sector_num, buf, nb_sectors);
}

void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
{
    *nb_sectors_ptr = bs->total_sectors;
}

/* force a given boot sector. */
void bdrv_set_boot_sector(BlockDriverState *bs, const uint8_t *data, int size)
{
    bs->boot_sector_enabled = 1;
    if (size > 512)
        size = 512;
    memcpy(bs->boot_sector_data, data, size);
    memset(bs->boot_sector_data + size, 0, 512 - size);
}

void bdrv_set_geometry_hint(BlockDriverState *bs, 
                            int cyls, int heads, int secs)
{
    bs->cyls = cyls;
    bs->heads = heads;
    bs->secs = secs;
}

void bdrv_set_type_hint(BlockDriverState *bs, int type)
{
    bs->type = type;
    bs->removable = ((type == BDRV_TYPE_CDROM ||
                      type == BDRV_TYPE_FLOPPY));
}

void bdrv_set_translation_hint(BlockDriverState *bs, int translation)
{
    bs->translation = translation;
}

void bdrv_get_geometry_hint(BlockDriverState *bs, 
                            int *pcyls, int *pheads, int *psecs)
{
    *pcyls = bs->cyls;
    *pheads = bs->heads;
    *psecs = bs->secs;
}

int bdrv_get_type_hint(BlockDriverState *bs)
{
    return bs->type;
}

int bdrv_get_translation_hint(BlockDriverState *bs)
{
    return bs->translation;
}

int bdrv_is_removable(BlockDriverState *bs)
{
    return bs->removable;
}

int bdrv_is_read_only(BlockDriverState *bs)
{
    return bs->read_only;
}

int bdrv_is_inserted(BlockDriverState *bs)
{
    return bs->inserted;
}

int bdrv_is_locked(BlockDriverState *bs)
{
    return bs->locked;
}

void bdrv_set_locked(BlockDriverState *bs, int locked)
{
    bs->locked = locked;
}

void bdrv_set_change_cb(BlockDriverState *bs, 
                        void (*change_cb)(void *opaque), void *opaque)
{
    bs->change_cb = change_cb;
    bs->change_opaque = opaque;
}

int bdrv_is_encrypted(BlockDriverState *bs)
{
    if (bs->backing_hd && bs->backing_hd->encrypted)
        return 1;
    return bs->encrypted;
}

int bdrv_set_key(BlockDriverState *bs, const char *key)
{
    int ret;
    if (bs->backing_hd && bs->backing_hd->encrypted) {
        ret = bdrv_set_key(bs->backing_hd, key);
        if (ret < 0)
            return ret;
        if (!bs->encrypted)
            return 0;
    }
    if (!bs->encrypted || !bs->drv || !bs->drv->bdrv_set_key)
        return -1;
    return bs->drv->bdrv_set_key(bs, key);
}

void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size)
{
    if (!bs->inserted || !bs->drv) {
        buf[0] = '\0';
    } else {
        pstrcpy(buf, buf_size, bs->drv->format_name);
    }
}

void bdrv_iterate_format(void (*it)(void *opaque, const char *name), 
                         void *opaque)
{
    BlockDriver *drv;

    for (drv = first_drv; drv != NULL; drv = drv->next) {
        it(opaque, drv->format_name);
    }
}

BlockDriverState *bdrv_find(const char *name)
{
    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
        if (!strcmp(name, bs->device_name))
            return bs;
    }
    return NULL;
}

void bdrv_iterate(void (*it)(void *opaque, const char *name), void *opaque)
{
    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
        it(opaque, bs->device_name);
    }
}

const char *bdrv_get_device_name(BlockDriverState *bs)
{
    return bs->device_name;
}

void bdrv_info(void)
{
    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
        term_printf("%s:", bs->device_name);
        term_printf(" type=");
        switch(bs->type) {
        case BDRV_TYPE_HD:
            term_printf("hd");
            break;
        case BDRV_TYPE_CDROM:
            term_printf("cdrom");
            break;
        case BDRV_TYPE_FLOPPY:
            term_printf("floppy");
            break;
        }
        term_printf(" removable=%d", bs->removable);
        if (bs->removable) {
            term_printf(" locked=%d", bs->locked);
        }
        if (bs->inserted) {
            term_printf(" file=%s", bs->filename);
            if (bs->backing_file[0] != '\0')
                term_printf(" backing_file=%s", bs->backing_file);
            term_printf(" ro=%d", bs->read_only);
            term_printf(" drv=%s", bs->drv->format_name);
            if (bs->encrypted)
                term_printf(" encrypted");
        } else {
            term_printf(" [not inserted]");
        }
        term_printf("\n");
    }
}

/**************************************************************/
/* RAW block driver */

typedef struct BDRVRawState {
    int fd;
} BDRVRawState;

static int raw_probe(const uint8_t *buf, int buf_size, const char *filename)
{
    return 1; /* maybe */
}

static int raw_open(BlockDriverState *bs, const char *filename)
{
    BDRVRawState *s = bs->opaque;
    int fd;
    int64_t size;
#ifdef _BSD
    struct stat sb;
#endif
#ifdef __sun__
    struct dk_minfo minfo;
    int rv;
#endif

    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;
    }
#ifdef _BSD
    if (!fstat(fd, &sb) && (S_IFCHR & sb.st_mode)) {
#ifdef DIOCGMEDIASIZE
	if (ioctl(fd, DIOCGMEDIASIZE, (off_t *)&size))
#endif
#ifdef CONFIG_COCOA
        size = LONG_LONG_MAX;
#else
        size = lseek(fd, 0LL, SEEK_END);
#endif
    } else
#endif
#ifdef __sun__
    /*
     * use the DKIOCGMEDIAINFO ioctl to read the size.
     */
    rv = ioctl ( fd, DKIOCGMEDIAINFO, &minfo );
    if ( rv != -1 ) {
        size = minfo.dki_lbsize * minfo.dki_capacity;
    } else /* there are reports that lseek on some devices
              fails, but irc discussion said that contingency
              on contingency was overkill */
#endif
    {
        size = lseek(fd, 0, SEEK_END);
    }
#ifdef _WIN32
    /* On Windows hosts it can happen that we're unable to get file size
       for CD-ROM raw device (it's inherent limitation of the CDFS driver). */
    if (size == -1)
        size = LONG_LONG_MAX;
#endif
    bs->total_sectors = size / 512;
    s->fd = fd;
    return 0;
}

static int raw_read(BlockDriverState *bs, int64_t sector_num, 
                    uint8_t *buf, int nb_sectors)
{
    BDRVRawState *s = bs->opaque;
    int ret;
    
    lseek(s->fd, sector_num * 512, SEEK_SET);
    ret = read(s->fd, buf, nb_sectors * 512);
    if (ret != nb_sectors * 512) 
        return -1;
    return 0;
}

static int raw_write(BlockDriverState *bs, int64_t sector_num, 
                     const uint8_t *buf, int nb_sectors)
{
    BDRVRawState *s = bs->opaque;
    int ret;
    
    lseek(s->fd, sector_num * 512, SEEK_SET);
    ret = write(s->fd, buf, nb_sectors * 512);
    if (ret != nb_sectors * 512) 
        return -1;
    return 0;
}

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

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 | O_LARGEFILE, 
              0644);
    if (fd < 0)
        return -EIO;
    ftruncate(fd, total_size * 512);
    close(fd);
    return 0;
}

BlockDriver bdrv_raw = {
    "raw",
    sizeof(BDRVRawState),
    raw_probe,
    raw_open,
    raw_read,
    raw_write,
    raw_close,
    raw_create,
};

void bdrv_init(void)
{
    bdrv_register(&bdrv_raw);
#ifndef _WIN32
    bdrv_register(&bdrv_cow);
#endif
    bdrv_register(&bdrv_qcow);
    bdrv_register(&bdrv_vmdk);
    bdrv_register(&bdrv_cloop);
    bdrv_register(&bdrv_dmg);
    bdrv_register(&bdrv_bochs);
    bdrv_register(&bdrv_vpc);
    bdrv_register(&bdrv_vvfat);
}