From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:47533) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1geyoa-0003Fr-NB for qemu-devel@nongnu.org; Thu, 03 Jan 2019 03:57:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1geyoZ-0001Cs-P5 for qemu-devel@nongnu.org; Thu, 03 Jan 2019 03:57:20 -0500 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Thu, 3 Jan 2019 09:56:35 +0100 Message-Id: <20190103085638.17600-3-philmd@redhat.com> In-Reply-To: <20190103085638.17600-1-philmd@redhat.com> References: <20190103085638.17600-1-philmd@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v5 2/5] block/sheepdog: Use QEMU_NONSTRING for non NUL-terminated arrays List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Dr. David Alan Gilbert" , Thomas Huth , David Hildenbrand , Igor Mammedov , Paolo Bonzini , Markus Armbruster , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Eric Blake , "Michael S. Tsirkin" , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Liu Yuan , Jeff Cody , Kevin Wolf , Max Reitz , "open list:Sheepdog" GCC 8 added a -Wstringop-truncation warning: The -Wstringop-truncation warning added in GCC 8.0 via r254630 for bug 81117 is specifically intended to highlight likely unintended uses of the strncpy function that truncate the terminating NUL character from the source string. This new warning leads to compilation failures: CC block/sheepdog.o qemu/block/sheepdog.c: In function 'find_vdi_name': qemu/block/sheepdog.c:1239:5: error: 'strncpy' specified bound 256 equa= ls destination size [-Werror=3Dstringop-truncation] strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ make: *** [qemu/rules.mak:69: block/sheepdog.o] Error 1 As described previous to the strncpy() calls, the use of strncpy() is correct here: /* This pair of strncpy calls ensures that the buffer is zero-filled, * which is desirable since we'll soon be sending those bytes, and * don't want the send_req to read uninitialized data. */ strncpy(buf, filename, SD_MAX_VDI_LEN); strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN); Use the QEMU_NONSTRING attribute, since this array is intended to store character arrays that do not necessarily contain a terminating NUL. Suggested-by: Michael S. Tsirkin Reviewed-by: Eric Blake Reviewed-by: Michael S. Tsirkin Signed-off-by: Philippe Mathieu-Daud=C3=A9 --- block/sheepdog.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/sheepdog.c b/block/sheepdog.c index 0125df9d49..5cd9618432 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -1224,7 +1224,7 @@ static int find_vdi_name(BDRVSheepdogState *s, cons= t char *filename, SheepdogVdiReq hdr; SheepdogVdiRsp *rsp =3D (SheepdogVdiRsp *)&hdr; unsigned int wlen, rlen =3D 0; - char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN]; + char buf[SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN] QEMU_NONSTRING; =20 fd =3D connect_to_sdog(s, errp); if (fd < 0) { --=20 2.17.2