From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:39514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TGHgW-0006Ae-4P for qemu-devel@nongnu.org; Mon, 24 Sep 2012 19:03:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TGHgT-0005XN-MJ for qemu-devel@nongnu.org; Mon, 24 Sep 2012 19:03:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4044) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TGHgT-0005X7-D6 for qemu-devel@nongnu.org; Mon, 24 Sep 2012 19:03:25 -0400 Date: Tue, 25 Sep 2012 01:04:36 +0200 From: "Michael S. Tsirkin" Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: [Qemu-devel] [PATCH 03/14] iov: add iov_cpy List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Jason Wang , Anthony Liguori , stefanha@linux.vnet.ibm.com, aurelien@aurel32.net 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..0dfcb28 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_cpy(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..f0daefa 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. Actual size is returned. + */ +size_t iov_cpy(struct iovec *dst_iov, unsigned int dst_iov_cnt, + const struct iovec *iov, unsigned int iov_cnt, + size_t offset, size_t bytes); -- MST