From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53795) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TgLsn-00056L-4g for qemu-devel@nongnu.org; Wed, 05 Dec 2012 15:47:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TgLsk-0002NI-I2 for qemu-devel@nongnu.org; Wed, 05 Dec 2012 15:47:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48752) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TgLsk-0002NB-AV for qemu-devel@nongnu.org; Wed, 05 Dec 2012 15:47:50 -0500 From: Stefan Hajnoczi Date: Wed, 5 Dec 2012 21:47:08 +0100 Message-Id: <1354740430-22452-10-git-send-email-stefanha@redhat.com> In-Reply-To: <1354740430-22452-1-git-send-email-stefanha@redhat.com> References: <1354740430-22452-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH v5 09/11] iov: add qemu_iovec_concat_iov() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Anthony Liguori , "Michael S. Tsirkin" , Blue Swirl , khoa@us.ibm.com, Stefan Hajnoczi , Paolo Bonzini , asias@redhat.com The qemu_iovec_concat() function copies a subset of a QEMUIOVector. The new qemu_iovec_concat_iov() function does the same for a iov/cnt pair. It is easy to define qemu_iovec_concat() in terms of qemu_iovec_concat_iov(). The existing code is mostly unchanged, except for the assertion src->size >= soffset, which cannot be efficiently checked upfront on a iov/cnt pair. Instead we assert upon hitting the end of src with an unsatisfied soffset. Signed-off-by: Stefan Hajnoczi --- iov.c | 39 +++++++++++++++++++++++++++------------ qemu-common.h | 3 +++ 2 files changed, 30 insertions(+), 12 deletions(-) diff --git a/iov.c b/iov.c index 6eed089..1d4c5fe 100644 --- a/iov.c +++ b/iov.c @@ -289,34 +289,49 @@ void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len) } /* - * Concatenates (partial) iovecs from src to the end of dst. + * Concatenates (partial) iovecs from src_iov to the end of dst. * It starts copying after skipping `soffset' bytes at the * beginning of src and adds individual vectors from src to * dst copies up to `sbytes' bytes total, or up to the end - * of src if it comes first. This way, it is okay to specify + * of src_iov if it comes first. This way, it is okay to specify * very large value for `sbytes' to indicate "up to the end * of src". * Only vector pointers are processed, not the actual data buffers. */ -void qemu_iovec_concat(QEMUIOVector *dst, - QEMUIOVector *src, size_t soffset, size_t sbytes) +void qemu_iovec_concat_iov(QEMUIOVector *dst, + struct iovec *src_iov, unsigned int src_cnt, + size_t soffset, size_t sbytes) { int i; size_t done; - struct iovec *siov = src->iov; assert(dst->nalloc != -1); - assert(src->size >= soffset); - for (i = 0, done = 0; done < sbytes && i < src->niov; i++) { - if (soffset < siov[i].iov_len) { - size_t len = MIN(siov[i].iov_len - soffset, sbytes - done); - qemu_iovec_add(dst, siov[i].iov_base + soffset, len); + for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) { + if (soffset < src_iov[i].iov_len) { + size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done); + qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len); done += len; soffset = 0; } else { - soffset -= siov[i].iov_len; + soffset -= src_iov[i].iov_len; } } - /* return done; */ + assert(soffset == 0); /* offset beyond end of src */ +} + +/* + * Concatenates (partial) iovecs from src to the end of dst. + * It starts copying after skipping `soffset' bytes at the + * beginning of src and adds individual vectors from src to + * dst copies up to `sbytes' bytes total, or up to the end + * of src if it comes first. This way, it is okay to specify + * very large value for `sbytes' to indicate "up to the end + * of src". + * Only vector pointers are processed, not the actual data buffers. + */ +void qemu_iovec_concat(QEMUIOVector *dst, + QEMUIOVector *src, size_t soffset, size_t sbytes) +{ + qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes); } void qemu_iovec_destroy(QEMUIOVector *qiov) diff --git a/qemu-common.h b/qemu-common.h index cef264c..4cc63e1 100644 --- a/qemu-common.h +++ b/qemu-common.h @@ -379,6 +379,9 @@ void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov); void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len); void qemu_iovec_concat(QEMUIOVector *dst, QEMUIOVector *src, size_t soffset, size_t sbytes); +void qemu_iovec_concat_iov(QEMUIOVector *dst, + struct iovec *src_iov, unsigned int src_cnt, + size_t soffset, size_t sbytes); void qemu_iovec_destroy(QEMUIOVector *qiov); void qemu_iovec_reset(QEMUIOVector *qiov); size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, -- 1.8.0.1