Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 53 insertions, 0 deletions

diff --git a/include/hw/stream.h b/include/hw/stream.h
new file mode 100644
index 000000000..f166facb0
--- /dev/null
+++ b/include/hw/stream.h
@@ -0,0 +1,53 @@
+#ifndef STREAM_H
+#define STREAM_H
+
+#include "qom/object.h"
+
+#define TYPE_STREAM_SINK "stream-sink"
+
+typedef struct StreamSinkClass StreamSinkClass;
+DECLARE_CLASS_CHECKERS(StreamSinkClass, STREAM_SINK,
+                       TYPE_STREAM_SINK)
+#define STREAM_SINK(obj) \
+     INTERFACE_CHECK(StreamSink, (obj), TYPE_STREAM_SINK)
+
+typedef struct StreamSink StreamSink;
+
+typedef void (*StreamCanPushNotifyFn)(void *opaque);
+
+struct StreamSinkClass {
+    InterfaceClass parent;
+    /**
+     * can push - determine if a stream sink is capable of accepting at least
+     * one byte of data. Returns false if cannot accept. If not implemented, the
+     * sink is assumed to always be capable of receiving.
+     * @notify: Optional callback that the sink will call when the sink is
+     * capable of receiving again. Only called if false is returned.
+     * @notify_opaque: opaque data to pass to notify call.
+     */
+    bool (*can_push)(StreamSink *obj, StreamCanPushNotifyFn notify,
+                     void *notify_opaque);
+    /**
+     * push - push data to a Stream sink. The number of bytes pushed is
+     * returned. If the sink short returns, the master must wait before trying
+     * again, the sink may continue to just return 0 waiting for the vm time to
+     * advance. The can_push() function can be used to trap the point in time
+     * where the sink is ready to receive again, otherwise polling on a QEMU
+     * timer will work.
+     * @obj: Stream sink to push to
+     * @buf: Data to write
+     * @len: Maximum number of bytes to write
+     * @eop: End of packet flag
+     */
+    size_t (*push)(StreamSink *obj, unsigned char *buf, size_t len, bool eop);
+};
+
+size_t
+stream_push(StreamSink *sink, uint8_t *buf, size_t len, bool eop);
+
+bool
+stream_can_push(StreamSink *sink, StreamCanPushNotifyFn notify,
+                void *notify_opaque);
+
+
+#endif /* STREAM_H */