Commit da557aac authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

block: Add bdrv_open_image() 



Add a common function for opening images to be used for block drivers
specified through BlockdevRefs in an option QDict. The difference from
bdrv_file_open() is that this function may invoke bdrv_open() instead,
allowing auto-detection of the driver to be used; and second, it
automatically extracts the BlockdevRef from the option QDict.

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 2a05cbe4

block.c

+73 −0
Original line number Diff line number Diff line
@@ -1040,6 +1040,79 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) 
    return 0;

}



/*

 * Opens a disk image whose options are given as BlockdevRef in another block

 * device's options.

 *

 * If force_raw is true, bdrv_file_open() will be used, thereby preventing any

 * image format auto-detection. If it is false and a filename is given,

 * bdrv_open() will be used for auto-detection.

 *

 * If allow_none is true, no image will be opened if filename is false and no

 * BlockdevRef is given. *pbs will remain unchanged and 0 will be returned.

 *

 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.

 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict

 * itself, all options starting with "${bdref_key}." are considered part of the

 * BlockdevRef.

 *

 * The BlockdevRef will be removed from the options QDict.

 */

int bdrv_open_image(BlockDriverState **pbs, const char *filename,

                    QDict *options, const char *bdref_key, int flags,

                    bool force_raw, bool allow_none, Error **errp)

{

    QDict *image_options;

    int ret;

    char *bdref_key_dot;

    const char *reference;



    bdref_key_dot = g_strdup_printf("%s.", bdref_key);

    qdict_extract_subqdict(options, &image_options, bdref_key_dot);

    g_free(bdref_key_dot);



    reference = qdict_get_try_str(options, bdref_key);

    if (!filename && !reference && !qdict_size(image_options)) {

        if (allow_none) {

            ret = 0;

        } else {

            error_setg(errp, "A block device must be specified for \"%s\"",

                       bdref_key);

            ret = -EINVAL;

        }

        goto done;

    }



    if (filename && !force_raw) {

        /* If a filename is given and the block driver should be detected

           automatically (instead of using none), use bdrv_open() in order to do

           that auto-detection. */

        BlockDriverState *bs;



        if (reference) {

            error_setg(errp, "Cannot reference an existing block device while "

                       "giving a filename");

            ret = -EINVAL;

            goto done;

        }



        bs = bdrv_new("");

        ret = bdrv_open(bs, filename, image_options, flags, NULL, errp);

        if (ret < 0) {

            bdrv_unref(bs);

        } else {

            *pbs = bs;

        }

    } else {

        ret = bdrv_file_open(pbs, filename, reference, image_options, flags,

                             errp);

    }



done:

    qdict_del(options, bdref_key);

    return ret;

}



/*

 * Opens a disk image (raw, qcow2, vmdk, ...)

 *

include/block/block.h

+3 −0
Original line number Diff line number Diff line
@@ -186,6 +186,9 @@ int bdrv_parse_discard_flags(const char *mode, int *flags); 
int bdrv_file_open(BlockDriverState **pbs, const char *filename,

                   const char *reference, QDict *options, int flags,

                   Error **errp);

int bdrv_open_image(BlockDriverState **pbs, const char *filename,

                    QDict *options, const char *bdref_key, int flags,

                    bool force_raw, bool allow_none, Error **errp);

int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);

int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,

              int flags, BlockDriver *drv, Error **errp);