On 21/06/2016 11:32, Stefan Hajnoczi wrote:
> I think the issue comes from the fact that you are considering something
> like load_block_module(const char *filename) as the API instead of
> request_block_driver(const char *driver_name). In the latter case it's
> possible to return a BlockDriver pointer. In the former it's not.
>
> The request_block_driver() approach requires a mapping from block driver
> names to modules. This can be achieved using a directory layout with
> symlinks (hmm...Windows portability?):
>
> /usr/lib/qemu/block/
> +--- sheepdog.so
> +--- by-protocol/
> +--- sheepdog+unix -> ../sheepdog.so
>
> request_block_driver() would look at
> /usr/lib/qemu/block/by-protocol/<protocol> to find the module file.
Another possibility is to add a ".loaded" element to the
block_driver_modules[] array and break the recursion (or infinite loop):
retry:
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (!strcmp(drv1->format_name, format_name)) {
return drv1;
}
}
for (i = 0; i < ARRAY_SIZE(block_driver_modules); ++i) {
if (!block_driver_modules[i].loaded &&
!strcmp(block_driver_modules[i].format_name, format_name)) {
block_driver_modules[i].loaded = true;
block_module_load_one(block_driver_modules[i].library_name);
goto retry;
}
}
BTW, please give a name to block_driver_modules[x]'s type, so that you
can assign &block_driver_modules[i] to a pointer and use that as a
shortcut.
Thanks,
Paolo
