From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40432) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z4VXh-0002oc-Cc for qemu-devel@nongnu.org; Mon, 15 Jun 2015 10:39:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z4VXb-0002zl-FS for qemu-devel@nongnu.org; Mon, 15 Jun 2015 10:39:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39816) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z4VXb-0002zZ-AA for qemu-devel@nongnu.org; Mon, 15 Jun 2015 10:39:11 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id C72202CD81E for ; Mon, 15 Jun 2015 14:39:10 +0000 (UTC) Message-ID: <557EE388.7070205@redhat.com> Date: Mon, 15 Jun 2015 16:39:04 +0200 From: Laszlo Ersek MIME-Version: 1.0 References: <557C32AC.7030903@redhat.com> <1434203538-8075-1-git-send-email-lersek@redhat.com> <1434203538-8075-3-git-send-email-lersek@redhat.com> <87pp4xm4nm.fsf@blackfin.pond.sub.org> In-Reply-To: <87pp4xm4nm.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 2/4] hw/core: rebase sysbus_get_fw_dev_path() to g_strdup_printf() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Marcel Apfelbaum , qemu-devel@nongnu.org, "Michael S. Tsirkin" On 06/15/15 16:23, Markus Armbruster wrote: > Laszlo Ersek writes: > >> Cc: Markus Armbruster >> Cc: Marcel Apfelbaum >> Cc: Michael S. Tsirkin >> Signed-off-by: Laszlo Ersek >> --- >> >> Notes: >> v4: >> - unchanged >> >> v3: >> - new in v3 >> >> hw/core/sysbus.c | 16 ++++++---------- >> 1 file changed, 6 insertions(+), 10 deletions(-) >> >> diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c >> index b53c351..0ebb4e2 100644 >> --- a/hw/core/sysbus.c >> +++ b/hw/core/sysbus.c >> @@ -281,19 +281,15 @@ static void sysbus_dev_print(Monitor *mon, DeviceState *dev, int indent) >> static char *sysbus_get_fw_dev_path(DeviceState *dev) >> { >> SysBusDevice *s = SYS_BUS_DEVICE(dev); >> - char path[40]; >> - int off; >> - >> - off = snprintf(path, sizeof(path), "%s", qdev_fw_name(dev)); >> >> if (s->num_mmio) { >> - snprintf(path + off, sizeof(path) - off, "@"TARGET_FMT_plx, >> - s->mmio[0].addr); >> - } else if (s->num_pio) { >> - snprintf(path + off, sizeof(path) - off, "@i%04x", s->pio[0]); >> + return g_strdup_printf("%s@"TARGET_FMT_plx, qdev_fw_name(dev), > > I'd put a space between "%s@" and TARGET_FMT_plx. I tried to copy the original format string very carefully, but you do have a point. I'll do it in the next version. > >> + s->mmio[0].addr); >> } >> - >> - return g_strdup(path); >> + if (s->num_pio) { >> + return g_strdup_printf("%s@i%04x", qdev_fw_name(dev), s->pio[0]); >> + } >> + return g_strdup(qdev_fw_name(dev)); >> } >> >> void sysbus_add_io(SysBusDevice *dev, hwaddr addr, > > Would be nice if we didn't have to triplicate qdev_fw_name(), but I > don't have better ideas. Right, I could "cache it" in a local variable, but then I'd have to triplicate the variable reference. And, runtime-wise, qdev_fw_name() is called only once, it's just spelled out thrice in the source. > > Bonus: no arbitrary length limit. Before your patch, it's 39 > characters, and the code breaks catastrophically when qdev_fw_name() is > longer: the second snprintf() is called with its first argument pointing > beyond path[], and its second argument underflowing to a huge size. > Textbook example of how not to use snprintf(). Worth mentioning in the > commit message? I was afraid that bashing on old code would only earn me some ire (not from you, mind you -- in general), so I didn't mention this fact in the commit message on purpose. :) I will, in the next version. > Reviewed-by: Markus Armbruster > Thanks! Laszlo