I was wondering why this never made it to the list - seems I just sent it to Michal... So here's what I sent... John On 05/16/2017 05:34 PM, John Ferlan wrote:

On 05/16/2017 10:03 AM, Michal Privoznik wrote:

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This is just a wrapper over new functions that have been just introduced: virStreamRecvFlags(), virStreamRecvHole(). It's very similar to virStreamRecvAll() except it handles sparse streams well.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- include/libvirt/libvirt-stream.h | 33 ++++++++++- src/libvirt-stream.c | 123 +++++++++++++++++++++++++++++++++++++++ src/libvirt_public.syms | 1 + 3 files changed, 154 insertions(+), 3 deletions(-)

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diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c index bedb6159a..6bf4c4f29 100644 --- a/src/libvirt-stream.c +++ b/src/libvirt-stream.c @@ -668,6 +668,129 @@ virStreamRecvAll(virStreamPtr stream, }

+/** + * virStreamSparseRecvAll: + * @stream: pointer to the stream object + * @handler: sink callback for writing data to application + * @holeHandler: stream hole callback for skipping holes + * @opaque: application defined data + * + * Receive the entire data stream, sending the data to the + * requested data sink @handler and calling the skip @holeHandler + * to generate holes for sparse stream targets. This is simply a + * convenient alternative to virStreamRecvFlags, for apps that do + * blocking-I/O. + * + * An example using this with a hypothetical file download + * API looks like: + * + * int mysink(virStreamPtr st, const char *buf, int nbytes, void *opaque) { + * int *fd = opaque; + * + * return write(*fd, buf, nbytes); + * } + * + * int myskip(virStreamPtr st, long long offset, void *opaque) { + * int *fd = opaque; + *

I think this is where perhaps the example of lseek in "off_t" chunks of "long long offset" would be applicable... Perhaps why I ended up in the off_t rathole before.

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+ * return lseek(*fd, offset, SEEK_CUR) == (off_t) -1 ? -1 : 0; + * } + * + * virStreamPtr st = virStreamNew(conn, 0); + * int fd = open("demo.iso", O_WRONLY); + * + * virConnectDownloadSparseFile(conn, st);

^^ This API doesn't exist... Of course neither did virConnectDownloadFile from whence you copied the example. Maybe both should be 'adjusted'.

Reviewed-by: John Ferlan <jferlan@redhat.com>

John

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+ * if (virStreamSparseRecvAll(st, mysink, myskip, &fd) < 0) { + * ...report an error ... + * goto done; + * } + * if (virStreamFinish(st) < 0) + * ...report an error... + * virStreamFree(st); + * close(fd); + * + * Note that @opaque data is shared between both @handler and + * @holeHandler callbacks. + * + * Returns 0 if all the data was successfully received. The caller + * should invoke virStreamFinish(st) to flush the stream upon + * success and then virStreamFree(st). + * + * Returns -1 upon any error, with virStreamAbort() already + * having been called, so the caller need only call virStreamFree(). + */

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