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From: Eric Blake <eblake@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org, Michael Roth <mdroth@linux.vnet.ibm.com>,
	programmingkidx@gmail.com, pbonzini@redhat.com
Subject: Re: [Qemu-devel] [PATCH 1/3] qmp-event: Avoid qobject_from_jsonf("%"PRId64)
Date: Wed, 23 Nov 2016 07:56:38 -0600	[thread overview]
Message-ID: <1fb53e28-ccb0-c83b-e4a2-d92d819e1b43@redhat.com> (raw)
In-Reply-To: <87wpfupaww.fsf@dusky.pond.sub.org>

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On 11/23/2016 07:45 AM, Markus Armbruster wrote:
> Eric Blake <eblake@redhat.com> writes:
> 
>> The qobject_from_jsonf() function implements a pseudo-printf
>> language for creating a QObject; however, it is hard-coded to
>> only parse a subset of formats understood by printf().  In
>> particular, any use of a 64-bit integer works only if the
>> system's definition of PRId64 matches what the parser expects;
>> which works on glibc (%lld) and mingw (%I64d), but not on
>> Mac OS (%qd).  Rather than enhance the parser, it is just as
>> easy to open-code the few callers that were relying on this
>> particular conversion.
>>
>> Reported by: G 3 <programmingkidx@gmail.com>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>  qapi/qmp-event.c | 12 +++++++-----
>>  1 file changed, 7 insertions(+), 5 deletions(-)

> Commit message claims to change "the few callers", patch changes just
> one.  Which of the two is right?

Rebase churn - there were four callers of qobject_from_jsonf() that I
originally identified, then I split it up into the one caller that used
%PRId64 vs. the other three that can be done differently.

> 
> In my opinion, the code becomes less readable.
> 
> We want to convert struct timeval members tv_sec (of type time_t) and
> tv_usec (of type suseconds_t) here.  Since qobject_from_jsonf() lacks
> conversion specifiers for time_t and suseconds_t, we convert to int64_t
> first, then use PRId64.  The problem is that we don't actually implement
> PRId64 everywhere.  Why not simply long long and %lld?

For 2.8, I can leave %lld support in qobject_from_jsonf(), and just cast
to long long instead of int64_t. I'd still like to propose the series
that kills all dynamic JSON for 2.9, but I don't mind posting a v2 of
this series.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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  reply	other threads:[~2016-11-23 13:56 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-23  4:16 [Qemu-devel] [PATCH for-2.8 0/3] Fix MacOS runtime failure of qobject_from_jsonf() Eric Blake
2016-11-23  4:16 ` [Qemu-devel] [PATCH 1/3] qmp-event: Avoid qobject_from_jsonf("%"PRId64) Eric Blake
2016-11-23 13:45   ` Markus Armbruster
2016-11-23 13:56     ` Eric Blake [this message]
2016-11-23 14:04       ` Eric Blake
2016-11-23  4:16 ` [Qemu-devel] [PATCH 2/3] test-qga: " Eric Blake
2016-11-23  9:23   ` Paolo Bonzini
2016-11-23 10:36     ` Eric Blake
2016-11-23 11:08       ` Eric Blake
2016-11-23 12:06       ` Paolo Bonzini
2016-11-23 14:05   ` Markus Armbruster
2016-11-23 14:14     ` Eric Blake
2016-11-23 16:55       ` Markus Armbruster
2016-11-23  4:16 ` [Qemu-devel] [PATCH 3/3] qapi: Drop support for qobject_from_jsonf("%"PRId64) Eric Blake
2016-11-23  9:25   ` Paolo Bonzini
2016-11-23 10:54     ` Eric Blake
2016-11-23 14:17       ` Markus Armbruster
2016-11-23 14:24         ` Eric Blake
2016-11-23 16:56           ` Markus Armbruster
2016-11-23 16:59             ` Eric Blake

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