From patchwork Tue Sep 25 11:12:14 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 186788 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 061082C0089 for ; Tue, 25 Sep 2012 21:44:55 +1000 (EST) Received: from localhost ([::1]:38871 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TGT3I-0002GE-5F for incoming@patchwork.ozlabs.org; Tue, 25 Sep 2012 07:11:44 -0400 Received: from eggs.gnu.org ([208.118.235.92]:47577) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TGT2c-0000dk-Ow for qemu-devel@nongnu.org; Tue, 25 Sep 2012 07:11:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TGT2R-0002ce-DZ for qemu-devel@nongnu.org; Tue, 25 Sep 2012 07:11:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55930) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TGT2R-0002bN-3n for qemu-devel@nongnu.org; Tue, 25 Sep 2012 07:10:51 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q8PBAeZ5002787 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 25 Sep 2012 07:10:41 -0400 Received: from redhat.com (vpn1-4-15.ams2.redhat.com [10.36.4.15]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id q8PBAc3L021972; Tue, 25 Sep 2012 07:10:39 -0400 Date: Tue, 25 Sep 2012 13:12:14 +0200 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org, Jason Wang , Anthony Liguori , stefanha@linux.vnet.ibm.com, aurelien@aurel32.net Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCHv2 03/14] iov: add iov_cpy X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Add API to copy part of iovec safely. Signed-off-by: Michael S. Tsirkin --- iov.c | 23 +++++++++++++++++++++++ iov.h | 9 +++++++++ 2 files changed, 32 insertions(+) diff --git a/iov.c b/iov.c index c6a66f0..b7378bf 100644 --- a/iov.c +++ b/iov.c @@ -228,3 +228,26 @@ void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, fprintf(fp, "\n"); } } + +unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, + const struct iovec *iov, unsigned int iov_cnt, + size_t offset, size_t bytes) +{ + size_t len; + unsigned int i, j; + for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) { + if (offset >= iov[i].iov_len) { + offset -= iov[i].iov_len; + continue; + } + len = MIN(bytes, iov[i].iov_len - offset); + + dst_iov[j].iov_base = iov[i].iov_base + offset; + dst_iov[j].iov_len = len; + j++; + bytes -= len; + offset = 0; + } + assert(offset == 0); + return j; +} diff --git a/iov.h b/iov.h index a73569f..34c8ec9 100644 --- a/iov.h +++ b/iov.h @@ -86,3 +86,12 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, */ void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt, FILE *fp, const char *prefix, size_t limit); + +/* + * Partial copy of vector from iov to dst_iov (data is not copied). + * dst_iov overlaps iov at a specified offset. + * size of dst_iov is at most bytes. dst vector count is returned. + */ +unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt, + const struct iovec *iov, unsigned int iov_cnt, + size_t offset, size_t bytes);