Re: [Qemu-devel] [PATCH RFC] qemu-io: Prefer stderr for error messages

[Eric Blake <eblake@redhat.com>]

On 12/13/18 6:21 AM, Wainer dos Santos Moschetta wrote:
> 
> On 12/12/2018 08:04 PM, Eric Blake wrote:
>> When a qemu-io command fails, it's best if the failure message
>> goes to stderr rather than stdout.
>>
>> Reported-by: Richard W.M. Jones <rjones@redhat.com>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>
>> RFC because at least iotest 60 (found by -qcow2 -g quick) breaks due
>> to reordering of output lines, and I'd rather know if we like this
>> idea before bothering to revisit all affected iotests (including
>> discovering if other slower ones have similar problems).

>>           if (!QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)) {
>> -            printf("%"PRId64" is not a sector-aligned value for 
>> 'count'\n",
>> -                   count);
>> +            fprintf(stderr,
>> +                    "%"PRId64" is not a sector-aligned value for 
>> 'count'\n",
> 
> Adding one space before and after PRId64 as in '"%" PRId64 " is not 
> (...)"' increases readability IMHO.

Pre-existing, but I don't mind fixing it while touching in the area.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org