Re: [Qemu-devel] [PATCH 5/8] qemu-img: img_create(): use Error object

[Markus Armbruster]

Kevin Wolf <address@hidden> writes:

> Am 18.10.2012 15:49, schrieb Luiz Capitulino:
>> On Thu, 18 Oct 2012 14:11:40 +0200
>> Kevin Wolf <address@hidden> wrote:
>> 
>>> Am 17.10.2012 21:35, schrieb Luiz Capitulino:
>>>> Signed-off-by: Luiz Capitulino <address@hidden>
>>>> ---
>>>>  qemu-img.c | 10 +++++++---
>>>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/qemu-img.c b/qemu-img.c
>>>> index 12fb6c2..dfde588 100644
>>>> --- a/qemu-img.c
>>>> +++ b/qemu-img.c
>>>> @@ -302,6 +302,7 @@ static int img_create(int argc, char **argv)
>>>>      const char *base_filename = NULL;
>>>>      char *options = NULL;
>>>>      QEMUOptionParameter *params = NULL;
>>>> +    Error *local_err = NULL;
>>>>  
>>>>      for(;;) {
>>>>          c = getopt(argc, argv, "F:b:f:he6o:");
>>>> @@ -362,9 +363,12 @@ static int img_create(int argc, char **argv)
>>>>          goto out;
>>>>      }
>>>>  
>>>> -    ret = bdrv_img_create(filename, fmt, base_filename, base_fmt,
>>>> -                          options, img_size, BDRV_O_FLAGS, &params, NULL);
>>>> -    if (ret < 0) {
>>>> +    bdrv_img_create(filename, fmt, base_filename, base_fmt,
>>>> +                    options, img_size, BDRV_O_FLAGS, &params, &local_err);
>>>> +    if (error_is_set(&local_err)) {
>>>> +        fprintf(stderr, "qemu-img: %s\n", error_get_pretty(local_err));
>>>
>>> This should use error_report() instead of adding the "qemu-img:" manually.
>> 
>> If you want to do it for consistency with the current code then ok,
>> I'll do it for v2. But I disagree qemu-img should keep using error_report(),
>> printing to hmp for example is something beyond the interests of a tool like
>> qemu-img.
>
> qemu-img doesn't have an HMP monitor, so it doesn't hurt either. If you
> want to replace it, replace it with a copy of qemu-error.c that only
> removes the monitor_vprintf() case. That is, in particular, leave all of
> the loc_*() functionality there, because this is something that is meant
> for use in command line parsers.

Strongly agreed on use of error_report().  Buys us uniform error
messages that can point to the location causing the error.  The fact
that error_report() does the right thing in monitor context is detail.

I don't see why purging a few monitor references from tools is worth
copying the file.  Stubbing out cur_mon and monitor_vprintf() in tools
is just fine, in my opinion.

> That qemu-img doesn't use these functions yet should be fixed. It has
> some good use cases for them.

Indeed.