Re: [PATCH 2/3] utils: Deprecate hex-with-suffix sizes

[Eric Blake <eblake@redhat.com>]

On 2/5/21 5:13 AM, Daniel P. Berrangé wrote:
> On Thu, Feb 04, 2021 at 01:07:07PM -0600, Eric Blake wrote:
>> Supporting '0x20M' looks odd, particularly since we have an 'E' suffix
>> that is ambiguous between a hex digit and the extremely large exibyte
>> suffix, as well as a 'B' suffix for bytes.  In practice, people using
>> hex inputs are specifying values in bytes (and would have written
>> 0x2000000, or possibly relied on default_suffix in the case of
>> qemu_strtosz_MiB), and the use of scaling suffixes makes the most
>> sense for inputs in decimal (where the user would write 32M).  But
>> rather than outright dropping support for hex-with-suffix, let's
>> follow our deprecation policy.  Sadly, since qemu_strtosz() does not
>> have an Err** parameter, we pollute to stderr.
> 
> Err** is only appropriate for errors, not warnings, so this statement
> can be removed.

The point of the comment was that we have no other mechanism for
reporting the deprecation other than polluting to stderr.  And if we
ever remove the support, we'll either have to silently reject input that
we used to accept, or plumb through Err** handling to allow better
reporting of WHY we are rejecting input.  But I didn't feel like adding
Err** support now.

>> @@ -309,6 +309,10 @@ static int do_strtosz(const char *nptr, const char **end,
>>      c = *endptr;
>>      mul = suffix_mul(c, unit);
>>      if (mul > 0) {
>> +        if (hex) {
>> +            fprintf(stderr, "Using a multiplier suffix on hex numbers "
>> +                    "is deprecated: %s\n", nptr);
> 
> warn_report(), since IIUC, that'll get into HMP response correctly.

Yes, that sounds better.  I'll use that in v2, as well as tweaking the
commit message.

> 
>> +        }
>>          endptr++;
>>      } else {
>>          mul = suffix_mul(default_suffix, unit);
> 
> Regards,
> Daniel
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org