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Re: [Qemu-devel] [PATCH 03/14] iov: add iov_cpy
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 03/14] iov: add iov_cpy |
Date: |
Mon, 24 Sep 2012 19:34:00 -0500 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
"Michael S. Tsirkin" <address@hidden> writes:
> Add API to copy part of iovec safely.
>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
> 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)
I think the readability f the cde wuld be imprved if yu added the
missing 'o' to iov_cpy.
Otherwise:
Reviewed-by: Anthony Liguori <address@hidden>
Regards,
Anthony Liguori
> +{
> + 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
- [Qemu-devel] [PATCH 00/14] virtio-net: iovec handling cleanup, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 01/14] virtio-net: track host/guest header length, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 03/14] iov: add iov_cpy, Michael S. Tsirkin, 2012/09/24
- Re: [Qemu-devel] [PATCH 03/14] iov: add iov_cpy,
Anthony Liguori <=
- [Qemu-devel] [PATCH 04/14] virtio-net: avoid sg copy, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 05/14] virtio-net: use safe iov operations for rx, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 07/14] virtio-net: first s/g is always at start of buf, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 02/14] iov: add const annotation, Michael S. Tsirkin, 2012/09/24
- [Qemu-devel] [PATCH 08/14] virtio-net: switch tx to safe iov functions, Michael S. Tsirkin, 2012/09/24