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

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 <>
Signed-off-by: default avatarKevin Wolf <>
parent 2a05cbe4
......@@ -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);
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\"",
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) {
} else {
*pbs = bs;
} else {
ret = bdrv_file_open(pbs, filename, reference, image_options, flags,
qdict_del(options, bdref_key);
return ret;
* Opens a disk image (raw, qcow2, vmdk, ...)
......@@ -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);
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