On 05/16/2017 10:03 AM, Michal Privoznik wrote:
Add a new flag to virStreamRecvFlags in order to handle being able to stop reading from the stream so that the consumer can generate a "hole" in stream target. Generation of a hole replaces the need to receive and handle a sequence of zero bytes for sparse stream targets.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- include/libvirt/libvirt-stream.h | 4 ++++ src/libvirt-stream.c | 34 +++++++++++++++++++++++++++++++++- 2 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/include/libvirt/libvirt-stream.h b/include/libvirt/libvirt-stream.h index feaa8ad64..c4baaf7a3 100644 --- a/include/libvirt/libvirt-stream.h +++ b/include/libvirt/libvirt-stream.h @@ -45,6 +45,10 @@ int virStreamRecv(virStreamPtr st, char *data, size_t nbytes);
+typedef enum { + VIR_STREAM_RECV_STOP_AT_HOLE = (1 << 0), +} virStreamRecvFlagsValues; + int virStreamRecvFlags(virStreamPtr st, char *data, size_t nbytes, diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c index dc0dc9ea3..bedb6159a 100644 --- a/src/libvirt-stream.c +++ b/src/libvirt-stream.c @@ -290,7 +290,7 @@ virStreamRecv(virStreamPtr stream, * @stream: pointer to the stream object * @data: buffer to read into from stream * @nbytes: size of @data buffer - * @flags: extra flags; not used yet, so callers should always pass 0 + * @flags: bitwise-OR of virStreamRecvFlagsValues * * Reads a series of bytes from the stream. This method may * block the calling application for an arbitrary amount @@ -300,6 +300,33 @@ virStreamRecv(virStreamPtr stream, * @flags. Calling this function with no @flags set (equal to * zero) is equivalent to calling virStreamRecv(stream, data, nbytes). * + * If flag VIR_STREAM_RECV_STOP_AT_HOLE is set, this function + * will stop reading from stream if it has reached a hole. In + * that case, -3 is returned and virStreamRecvHole() should be + * called to get the hole size. An example using this flag might + * look like this: + * + * while (1) { + * char buf[4096]; + * + * int ret = virStreamRecvFlags(st, buf, len, VIR_STREAM_STOP_AT_HOLE); + * if (ret < 0) { + * if (ret == -3) { + * long long len; + * ret = virStreamRecvHole(st, &len, 0); + * if (ret < 0) { + * ...error.. + * } else { + * ...seek len bytes in target...
Do/should we care to point out that @len is a "long long" and seeking is done in chunks of "off_t"? Reviewed-by: John Ferlan <jferlan@redhat.com> John [...]