Received: from eggs.gnu.org ([2001:4830:134:3::10]:36270) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlnZk-0001mk-K4 for qemu-devel@nongnu.org; Sat, 17 May 2014 18:59:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WlnZe-0002UP-UC for qemu-devel@nongnu.org; Sat, 17 May 2014 18:59:32 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:57683 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlnZe-0002Tl-Ju for qemu-devel@nongnu.org; Sat, 17 May 2014 18:59:26 -0400 From: Peter Lieven Date: Sun, 18 May 2014 00:58:17 +0200 Message-Id: <1400367499-12465-2-git-send-email-pl@kamp.de> In-Reply-To: <1400367499-12465-1-git-send-email-pl@kamp.de> References: <1400367499-12465-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCHv5 1/3] util: add qemu_iovec_is_zero List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, Peter Lieven , stefanha@redhat.com, pbonzini@redhat.com Signed-off-by: Peter Lieven --- include/qemu-common.h | 1 + util/iov.c | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/include/qemu-common.h b/include/qemu-common.h index 3f3fd60..66ceceb 100644 --- a/include/qemu-common.h +++ b/include/qemu-common.h @@ -318,6 +318,7 @@ void qemu_iovec_concat(QEMUIOVector *dst, void qemu_iovec_concat_iov(QEMUIOVector *dst, struct iovec *src_iov, unsigned int src_cnt, size_t soffset, size_t sbytes); +bool qemu_iovec_is_zero(QEMUIOVector *qiov); void qemu_iovec_destroy(QEMUIOVector *qiov); void qemu_iovec_reset(QEMUIOVector *qiov); size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, diff --git a/util/iov.c b/util/iov.c index 6569b5a..622db81 100644 --- a/util/iov.c +++ b/util/iov.c @@ -335,6 +335,27 @@ void qemu_iovec_concat(QEMUIOVector *dst, qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); } +/* + * check if the contents of the iovecs are all zero + */ +bool qemu_iovec_is_zero(QEMUIOVector *qiov) +{ + int i; + for (i = 0; i < qiov->niov; i++) { + size_t offs = QEMU_ALIGN_DOWN(qiov->iov[i].iov_len, 4 * sizeof(long)); + uint8_t *ptr = qiov->iov[i].iov_base; + if (offs && !buffer_is_zero(qiov->iov[i].iov_base, offs)) { + return false; + } + for (; offs < qiov->iov[i].iov_len; offs++) { + if (ptr[offs]) { + return false; + } + } + } + return true; +} + void qemu_iovec_destroy(QEMUIOVector *qiov) { assert(qiov->nalloc != -1); -- 1.7.9.5