From nobody Sat Sep 27 13:02:51 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 15460213813011002.8406687339277; Fri, 28 Dec 2018 10:23:01 -0800 (PST) Received: from localhost ([127.0.0.1]:32769 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gcwmh-0001ia-PS for importer@patchew.org; Fri, 28 Dec 2018 13:22:59 -0500 Received: from eggs.gnu.org ([208.118.235.92]:47710) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gcwl0-0001GL-Fa for qemu-devel@nongnu.org; Fri, 28 Dec 2018 13:22:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gcwkI-0006zZ-Br for qemu-devel@nongnu.org; Fri, 28 Dec 2018 13:21:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42206) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gcw1j-0001Wc-G3 for qemu-devel@nongnu.org; Fri, 28 Dec 2018 12:34:30 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BF48A13A9B; Fri, 28 Dec 2018 17:34:18 +0000 (UTC) Received: from x1w.redhat.com (ovpn-204-58.brq.redhat.com [10.40.204.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C655A1001944; Fri, 28 Dec 2018 17:34:13 +0000 (UTC) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Date: Fri, 28 Dec 2018 18:33:52 +0100 Message-Id: <20181228173356.15359-2-philmd@redhat.com> In-Reply-To: <20181228173356.15359-1-philmd@redhat.com> References: <20181228173356.15359-1-philmd@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 28 Dec 2018 17:34:18 +0000 (UTC) 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: 209.132.183.28 Subject: [Qemu-devel] [PATCH v4 1/5] qemu/compiler: Define QEMU_NONSTRING X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Juan Quintela , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , David Hildenbrand , "Dr. David Alan Gilbert" , Markus Armbruster , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , "Michael S. Tsirkin" , Igor Mammedov , Paolo Bonzini , David Gibson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" GCC 8 introduced the -Wstringop-truncation checker to detect truncation by the strncat and strncpy functions (closely related to -Wstringop-overflow, which detect buffer overflow by string-modifying functions declared in ). In tandem of -Wstringop-truncation, the "nonstring" attribute was added: The nonstring variable attribute specifies that an object or member declaration with type array of char, signed char, or unsigned char, or pointer to such a type is intended to store character arrays that do not necessarily contain a terminating NUL. This is useful in detecting uses of such arrays or pointers with functions that expect NUL-terminated strings, and to avoid warnings when such an array or pointer is used as an argument to a bounded string manipulation function such as strncpy. From the GCC manual: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-A= ttributes.html#index-nonstring-variable-attribute Add the QEMU_NONSTRING macro which checks if the compiler supports this attribute. Suggested-by: Michael S. Tsirkin Reviewed-by: Eric Blake Reviewed-by: Michael S. Tsirkin Signed-off-by: Philippe Mathieu-Daud=C3=A9 Reviewed-by: Richard Henderson Reviewed-by: Thomas Huth --- v4: reordered the commit description to make sens (eblake) Note this trigger the following checkpatch warning (patchew): WARNING: architecture specific defines should be avoided #50: FILE: include/qemu/compiler.h:163: +#if __has_attribute(nonstring) --- include/qemu/compiler.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 261842beae..2d8f507c73 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -151,6 +151,21 @@ # define QEMU_ERROR(X) #endif =20 +/* + * The nonstring variable attribute specifies that an object or member + * declaration with type array of char or pointer to char is intended + * to store character arrays that do not necessarily contain a terminating + * NUL character. This is useful in detecting uses of such arrays or point= ers + * with functions that expect NUL-terminated strings, and to avoid warnings + * when such an array or pointer is used as an argument to a bounded string + * manipulation function such as strncpy. + */ +#if __has_attribute(nonstring) +# define QEMU_NONSTRING __attribute__((nonstring)) +#else +# define QEMU_NONSTRING +#endif + /* Implement C11 _Generic via GCC builtins. Example: * * QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x) --=20 2.17.2