On Wed, Jun 22, 2016 at 04:43:24PM +0200, 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 @length, 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@xxxxxxxxxx>
> ---
> include/libvirt/libvirt-stream.h | 3 +++
> src/driver-stream.h | 5 ++++
> src/libvirt-stream.c | 57 ++++++++++++++++++++++++++++++++++++++++
> src/libvirt_public.syms | 1 +
> 4 files changed, 66 insertions(+)
>
> diff --git a/include/libvirt/libvirt-stream.h b/include/libvirt/libvirt-stream.h
> index bee2516..4e0a599 100644
> --- a/include/libvirt/libvirt-stream.h
> +++ b/include/libvirt/libvirt-stream.h
> @@ -50,6 +50,9 @@ int virStreamRecvFlags(virStreamPtr st,
> size_t nbytes,
> unsigned int flags);
>
> +int virStreamSkip(virStreamPtr st,
> + unsigned long long length);
> +
>
> /**
> * virStreamSourceFunc:
> diff --git a/src/driver-stream.h b/src/driver-stream.h
> index d4b0480..20ea13f 100644
> --- a/src/driver-stream.h
> +++ b/src/driver-stream.h
> @@ -42,6 +42,10 @@ typedef int
> unsigned int flags);
>
> typedef int
> +(*virDrvStreamSkip)(virStreamPtr st,
> + unsigned long long length);
> +
> +typedef int
> (*virDrvStreamEventAddCallback)(virStreamPtr stream,
> int events,
> virStreamEventCallback cb,
> @@ -68,6 +72,7 @@ struct _virStreamDriver {
> virDrvStreamSend streamSend;
> virDrvStreamRecv streamRecv;
> virDrvStreamRecvFlags streamRecvFlags;
> + virDrvStreamSkip streamSkip;
> virDrvStreamEventAddCallback streamEventAddCallback;
> virDrvStreamEventUpdateCallback streamEventUpdateCallback;
> virDrvStreamEventRemoveCallback streamEventRemoveCallback;
> diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c
> index 80b2d47..55f3ef5 100644
> --- a/src/libvirt-stream.c
> +++ b/src/libvirt-stream.c
> @@ -346,6 +346,63 @@ virStreamRecvFlags(virStreamPtr stream,
>
>
> /**
> + * virStreamSkip:
> + * @stream: pointer to the stream object
> + * @length: number of bytes to skip
> + *
> + * Skip @length 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.
> + *
> + * An example using this with a hypothetical file upload API
> + * looks like:
> + *
> + * virStream st;
> + *
> + * while (1) {
> + * char buf[4096];
> + * size_t len;
> + * if (..in hole...) {
> + * ..get hole size...
> + * virStreamSkip(st, len);
> + * } else {
> + * ...read len bytes...
> + * virStreamSend(st, buf, len);
> + * }
> + * }
> + *
> + * Returns 0 on success,
> + * -1 error
> + */
> +int
> +virStreamSkip(virStreamPtr stream,
> + unsigned long long length)
> +{
> + VIR_DEBUG("stream=%p, length=%llu", stream, length);
> +
> + virResetLastError();
> +
> + virCheckStreamReturn(stream, -1);
> +
> + if (stream->driver &&
> + stream->driver->streamSkip) {
> + int ret;
> + ret = (stream->driver->streamSkip)(stream, length);
> + if (ret < 0)
> + goto error;
> + return ret;
> + }
> +
> + virReportUnsupportedError();
> +
> + error:
> + virDispatchError(stream->conn);
> + return -1;
> +}
> +
> +
> +/**
> * virStreamSendAll:
> * @stream: pointer to the stream object
> * @handler: source callback for reading data from application
> diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms
> index d013d9f..5b536eb 100644
> --- a/src/libvirt_public.syms
> +++ b/src/libvirt_public.syms
> @@ -739,6 +739,7 @@ LIBVIRT_2.0.0 {
> virDomainSetGuestVcpus;
> virConnectStoragePoolEventRegisterAny;
> virStreamRecvFlags;
> + virStreamSkip;
> } LIBVIRT_1.3.3;
We can put this in a 2.1.0 block now
ACK
Regards,
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list