[libvirt] [PATCH 04/27] Introduce virStreamSkip

Eric Blake eblake at redhat.com
Thu May 5 14:37:54 UTC 2016


On 04/28/2016 04:04 AM, Michal Privoznik wrote:
> This API can be used to tell the other side of the stream to skip
> some bytes in the stream. This can be used to create a sparse
> file on the receiving side of a stream.
> 
> It takes just one argument @offset, which says how big the hole
> is. Since our streams are not rewindable like regular files, we
> don't need @whence argument like seek(2) has.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  include/libvirt/libvirt-stream.h |  3 +++
>  src/driver-stream.h              |  5 +++++
>  src/libvirt-stream.c             | 40 ++++++++++++++++++++++++++++++++++++++++
>  src/libvirt_public.syms          |  5 +++++
>  4 files changed, 53 insertions(+)
> 

> +++ b/src/libvirt-stream.c
> @@ -286,6 +286,46 @@ virStreamRecv(virStreamPtr stream,
>  
>  
>  /**
> + * virStreamSkip:
> + * @stream: pointer to the stream object
> + * @offset: number of bytes to skip
> + *
> + * Skip @offset bytes in the stream. This is useful when there's
> + * no actual data in the stream, just a hole. If that's the case,
> + * this API can be used to skip the hole properly instead of
> + * transmitting zeroes to the other side.
> + *
> + * Returns 0 on success,
> + *        -1 error
> + */
> +int
> +virStreamSkip(virStreamPtr stream,
> +              unsigned long long offset)

'offset' is a bit misleading - you're not skipping _to_ the given
offset, so much as _over_ length bytes.  I'd name it 'length'.

Otherwise looks okay.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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