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Mon, 2 Mar 2026 11:58:09 +0000 (UTC) Received: from redhat.com (unknown [10.45.226.21]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B7F8C19560A3; Mon, 2 Mar 2026 11:58:03 +0000 (UTC) Date: Mon, 2 Mar 2026 11:57:59 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: Akihiko Odaki , qemu-devel@nongnu.org, Viktor Prutyanov , Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Michael Roth , Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Keith Busch , Klaus Jensen , Jesper Devantier , qemu-block@nongnu.org Subject: Re: [PATCH v2 3/4] tests: Grow buffers for double string Message-ID: References: <20260302-nvme-v2-0-37ad8b5788c3@rsg.ci.i.u-tokyo.ac.jp> <20260302-nvme-v2-3-37ad8b5788c3@rsg.ci.i.u-tokyo.ac.jp> <87pl5m1mad.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87pl5m1mad.fsf@pond.sub.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -8 X-Spam_score: -0.9 X-Spam_bar: / X-Spam_report: (-0.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.012, RCVD_IN_VALIDITY_RPBL_BLOCKED=1.188, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Mar 02, 2026 at 12:52:10PM +0100, Markus Armbruster wrote: > Akihiko Odaki writes: > > > A string that represents a double can be long if it is an exponentially > > large number. > > > > Signed-off-by: Akihiko Odaki > > --- > > tests/unit/test-qobject-input-visitor.c | 2 +- > > tests/unit/test-qobject-output-visitor.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/tests/unit/test-qobject-input-visitor.c b/tests/unit/test-qobject-input-visitor.c > > index 84bdcdf702e0..baff9243313c 100644 > > --- a/tests/unit/test-qobject-input-visitor.c > > +++ b/tests/unit/test-qobject-input-visitor.c > > @@ -583,7 +583,7 @@ static void test_visitor_in_list_struct(TestInputVisitorData *data, > > > > i = 0; > > for (num_list = arrs->number; num_list; num_list = num_list->next) { > > - char expected[32], actual[32]; > > + char expected[318], actual[318]; > > Where does 318 come from? If we're concerned about buffer sizes being too short, then that is a strong sign we should be using g_strdup_printf instead of sprintf with a bigger magic size. As you say below though, it is better if we eliminate the string formatting entirely here since it is irrelevant for the goals of this test. > > > > > sprintf(expected, "%.6f", (double)i / 3); > > sprintf(actual, "%.6f", num_list->value); > g_assert_cmpstr(expected, ==, actual); > i++; > } > > Existing code is safe, because the numbers run from 0, 1.0/3, ..., > 31.0/3. > > Its purpose is to check the input visitor parses number arrays > correctly. Doing it this way is questionable. Elsewhere in this file, > we get away with the equivalent of > > g_assert_cmpfloat(num_list->value, ==, (double)i / 3); > > Yes, double can't represent the fractions exactly, but if we're > concerned about that, we should test the difference is less than > epsilon, or simply use representable values. > > > diff --git a/tests/unit/test-qobject-output-visitor.c b/tests/unit/test-qobject-output-visitor.c > > index 407ab9ed505a..ae05a726f775 100644 > > --- a/tests/unit/test-qobject-output-visitor.c > > +++ b/tests/unit/test-qobject-output-visitor.c > > @@ -571,7 +571,7 @@ static void test_visitor_out_list_struct(TestOutputVisitorData *data, > > i = 0; > > QLIST_FOREACH_ENTRY(qlist, e) { > > QNum *qvalue = qobject_to(QNum, qlist_entry_obj(e)); > > - char expected[32], actual[32]; > > + char expected[318], actual[318]; > > > > g_assert(qvalue); > > sprintf(expected, "%.6f", (double)i / 3); > > Likewise. > With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|