lib: add new stream function to reorganize buffer

The function was originally implemented for zebra data plane FPM plugin,
but another code places could use it.

Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/stream.c b/lib/stream.c
index dc207c16a4..e4e37b7315 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -1372,3 +1372,19 @@ void stream_fifo_free(struct stream_fifo *fifo)
 	stream_fifo_deinit(fifo);
 	XFREE(MTYPE_STREAM_FIFO, fifo);
 }
+
+void stream_pulldown(struct stream *s)
+{
+	size_t rlen = STREAM_READABLE(s);
+
+	/* No more data, so just move the pointers. */
+	if (rlen == 0) {
+		stream_reset(s);
+		return;
+	}
+
+	/* Move the available data to the beginning. */
+	memmove(s->data, &s->data[s->getp], rlen);
+	s->getp = 0;
+	s->endp = rlen;
+}