Re: [Qemu-devel] [PATCH 2/3] qemu-io: Respect early image end for map

[Max Reitz <mreitz@redhat.com>]

Am 10.10.2014 um 14:03 schrieb Benoît Canet:
>> +        } else if (!num) {
>> +            error_report("Unexpected end of image");
>> +            return 0;
> I think this test can miss some case of Unexpected end of image.
>
> For example supose that in map_is_allocated the first bdrv_is_allocated
> actually succeed then *pnum = num. Then the bottom loop has exit on failure
> and the function return.
>
> in map_f &num is map_is_allocated *pnum so map_f's num != 0 and this very test
> fails to see the unexpected end of image error.

num != 0 because some sectors where successfully queried. In my opinion, 
we should print the information about them we have. Then, the do-while 
loop is repeated; and this time, map_is_allocated() either again returns 
num > 0 (for whatever reason, but I'd be fine with it) or, more 
probably, it'll be num == 0 this time. So the error is not missed, it's 
just printed one iteration later.

Max

> Best regards
>
> Benoît
>
>>           }
>>   
>>           retstr = ret ? "    allocated" : "not allocated";
>> -- 
>> 2.0.4
>>
>>