On 05/16/2017 10:03 AM, Michal Privoznik wrote: > This API is 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 @length argument, which says how big the hole is. This > skipping is done from the current point of stream. Since our > streams are not rewindable like regular files, we don't need > @whence argument like seek(2) has. > > Signed-off-by: Michal Privoznik <mpriv...@redhat.com> > --- > include/libvirt/libvirt-stream.h | 4 +++ > src/driver-stream.h | 6 ++++ > src/libvirt-stream.c | 61 > ++++++++++++++++++++++++++++++++++++++++ > src/libvirt_public.syms | 1 + > 4 files changed, 72 insertions(+) >
[...] > diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c > index 7535deb3c..a09896dcd 100644 > --- a/src/libvirt-stream.c > +++ b/src/libvirt-stream.c > @@ -344,6 +344,67 @@ virStreamRecvFlags(virStreamPtr stream, > } > > > +/** > + * virStreamSendHole: > + * @stream: pointer to the stream object > + * @length: number of bytes to skip > + * @flags: extra flags; not used yet, so callers should always pass 0 > + * > + * Rather than transmitting empty file space, this API directs > + * the @stream target to create @length bytes of empty space. > + * This API would be used when uploading or downloading sparsely > + * populated files to avoid the needless copy of empty file > + * space. > + * > + * 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... > + * virStreamSendHole(st, len, 0); > + * } else { > + * ...read len bytes... > + * virStreamSend(st, buf, len); > + * } > + * } > + * > + * Returns 0 on success, > + * -1 error > + */ > +int > +virStreamSendHole(virStreamPtr stream, > + long long length, > + unsigned int flags) > +{ > + VIR_DEBUG("stream=%p, length=%lld flags=%x", > + stream, length, flags); > + > + virResetLastError(); > + > + virCheckStreamReturn(stream, -1); Perhaps some preventative programming: virCheckNonNegativeArgGoto(length, error); Although that would mean calling virDispatchError unless there was some sort of virCheck*ArgReturn(length, -1) Reviewed-by: John Ferlan <jfer...@redhat.com> John [...] -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list