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Tue, 26 Nov 2019 09:33:14 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3FFFD1138606; Tue, 26 Nov 2019 10:33:13 +0100 (CET) From: Markus Armbruster To: Tao Xu Subject: Re: [PATCH v17 02/14] util/cutils: Use qemu_strtold_finite to parse size References: <20191122074826.1373-1-tao3.xu@intel.com> <20191122074826.1373-3-tao3.xu@intel.com> <87tv6sjvfi.fsf@dusky.pond.sub.org> Date: Tue, 26 Nov 2019 10:33:13 +0100 In-Reply-To: (Tao Xu's message of "Tue, 26 Nov 2019 16:31:56 +0800") Message-ID: <87h82r9e3q.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: n5nQLcM6NCWasNl98fcqwA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "lvivier@redhat.com" , "thuth@redhat.com" , "ehabkost@redhat.com" , "mst@redhat.com" , "sw@weilnetz.de" , "Du, Fan" , "mdroth@linux.vnet.ibm.com" , "qemu-devel@nongnu.org" , "jonathan.cameron@huawei.com" , "imammedo@redhat.com" , "Liu, Jingqi" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Tao Xu writes: > On 11/25/2019 2:56 PM, Markus Armbruster wrote: >> Tao Xu writes: >> >>> Support full 64bit precision, modify related test cases. >> >> That's not true in general: long double need not be any wider than >> double. >> >> It might be true on the host machines we support, but I don't know. If >> we decide to rely on it, we better make the build fail when the host >> machine doesn't meet our expectations, preferably in configure. >> > [...] >>> - if ((val * mul >=3D 0xfffffffffffffc00) || val < 0) { >>> + /* Values > UINT64_MAX overflow uint64_t */ >>> + if ((val * mul > UINT64_MAX) || val < 0) { >>> retval =3D -ERANGE; >>> goto out; >>> } >> >> Not portable. If it was, we'd have made this changd long ago :) >> > > OK. So the suitable solution is what you suggested in v14? > > "A possible alternative is to parse the numeric part both as a double > and as a 64 bit unsigned integer, then use whatever consumes more > characters. This enables providing full 64 bits unless you actually > use > a fraction." Yes, that bypasses the portability issue. > I will try this way. Go ahead.