Am 04.11.2010 14:14, schrieb Anthony Liguori:
> On 11/04/2010 07:54 AM, Kevin Wolf wrote:
>> Am 27.10.2010 20:19, schrieb Anthony Liguori:
>>
>>> Signed-off-by: Anthony Liguori<aligu...@us.ibm.com>
>>>
>>> diff --git a/block.c b/block.c
>>> index 1a965b2..00b6f21 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -603,10 +603,16 @@ int bdrv_open(BlockDriverState *bs, const char
>>> *filename, int flags,
>>> BlockDriver *back_drv = NULL;
>>>
>>> bs->backing_hd = bdrv_new("");
>>> - path_combine(backing_filename, sizeof(backing_filename),
>>> - filename, bs->backing_file);
>>> - if (bs->backing_format[0] != '\0')
>>> - back_drv = bdrv_find_format(bs->backing_format);
>>> + back_drv = bdrv_find_protocol(bs->backing_file);
>>> + if (!back_drv) {
>>>
>> If no protocol is specified, bdrv_find_protocol doesn't return NULL but
>> the file: driver.
>>
>
> An ugly way to handle this would be to do if (strstr(bs->backing_file,
> ":") == NULL) instead.
Ugly indeed.
> A deeper refactoring could return NULL in bdrv_find_protocol and fixup
> the callers to default to file: if none are specified.
NULL is already used for errors, so we'd have to have something like
int bdrv_find_protocol(const char *filename, BlockDriver **drv)
in order to be able to distinguish "invalid protocol" from "no explicit
protocol". You could rename this function and retain a
bdrv_find_protocol with the old prototype as a wrapper that returns file
instead of NULL (there are several callers that expect this behaviour,
so probably it makes sense to have it in a central place).
Does that sound reasonable?
Kevin
