Re: [Qemu-devel] [PATCH V4 2/6] qcow2: add error message in qcow2_write_snapshots()

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

于 2013/11/5 3:46, Eric Blake 写道:
> On 11/03/2013 06:48 PM, Wenchao Xia wrote:
>>> On 14.10.2013 23:52, Wenchao Xia wrote:
>>>> The function still returns int since qcow2_snapshot_delete() will
>>>> return the number.
>>>>
>
>
>>>> @@ -227,24 +239,40 @@ static int
>>>> qcow2_write_snapshots(BlockDriverState *bs)
>>>>
>>>>            ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
>>>>            if (ret < 0) {
>>>> +            error_setg(errp,
>>>> +                       "Failed in write of snapshot header at %"
>>>> +                       PRIi64 " with size %" PRIu64 ": %d (%s)",
>>>> +                       offset, sizeof(h), ret, strerror(-ret));
>>>
>>> Again, on 32 bit systems, sizeof(size_t) is generally 4 and not 8 (you
>>> may want to cast sizeof(h) to int and just use %d).
>>>
>>
>>    Maybe caset as (int64_t)sizeof(h) to avoid possible incomplete value?
>
> If we have objects larger than 2G (such that sizeof(h) would require
> more than 31 bits), we have other issues to worry about.  Casting to int
> and using %d is safe enough.
>
  OK, will use %d.