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authorKevin Wolf <kwolf@redhat.com>2013-03-18 16:40:51 +0100
committerKevin Wolf <kwolf@redhat.com>2013-03-22 17:51:32 +0100
commitc2ad1b0c465a9ea8375eaff14bbd85705c673f73 (patch)
tree705456a5885c9ac7223fa2b75158e09adbc1d38f /include
parentf5866fa438bff586f215c137dc71edb4e0770536 (diff)
block: Allow omitting the file name when using driver-specific options
After this patch, using -drive with an empty file name continues to open the file if driver-specific options are used. If no driver-specific options are specified, the semantics stay as it was: It defines a drive without an inserted medium. In order to achieve this, bdrv_open() must be made safe to work with a NULL filename parameter. The assumption that is made is that only block drivers which implement bdrv_parse_filename() support using driver specific options and could therefore work without a filename. These drivers must make sure to cope with NULL in their implementation of .bdrv_open() (this is only NBD for now). For all other drivers, the block layer code will make sure to error out before calling into their code - they can't possibly work without a filename. Now an NBD connection can be opened like this: qemu-system-x86_64 -drive file.driver=nbd,file.port=1234,file.host=::1 Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/block/block_int.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 1b06a11590..0986a2d6ac 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -75,6 +75,9 @@ struct BlockDriver {
int instance_size;
int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
int (*bdrv_probe_device)(const char *filename);
+
+ /* Any driver implementing this callback is expected to be able to handle
+ * NULL file names in its .bdrv_open() implementation */
void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp);
/* For handling image reopen for split or non-split files */