[Qemu-devel] [RfC PATCH 05/10] io: add qio_buffer_move_empty

[Gerd Hoffmann <kraxel@redhat.com>]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/io/buffer.h | 10 ++++++++++
 io/buffer.c         | 14 ++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/io/buffer.h b/include/io/buffer.h
index cffad19..1dddc73 100644
--- a/include/io/buffer.h
+++ b/include/io/buffer.h
@@ -127,4 +127,14 @@ uint8_t *qio_buffer_end(QIOBuffer *buffer);
  */
 gboolean qio_buffer_empty(QIOBuffer *buffer);
 
+/**
+ * qio_buffer_move_empty:
+ * @to: destination buffer object
+ * @from: source buffer object
+ *
+ * Moves buffer, without copying data.  'to' buffer must be empty.
+ * 'from' buffer is empty and zero-sized on return.
+ */
+void qio_buffer_move_empty(QIOBuffer *to, QIOBuffer *from);
+
 #endif /* QIO_BUFFER_H__ */
diff --git a/io/buffer.c b/io/buffer.c
index daa3ebf..09ca321 100644
--- a/io/buffer.c
+++ b/io/buffer.c
@@ -77,3 +77,17 @@ void qio_buffer_advance(QIOBuffer *buffer, size_t len)
             (buffer->offset - len));
     buffer->offset -= len;
 }
+
+void qio_buffer_move_empty(QIOBuffer *to, QIOBuffer *from)
+{
+    assert(to->offset == 0);
+
+    g_free(to->buffer);
+    to->offset = from->offset;
+    to->capacity = from->capacity;
+    to->buffer = from->buffer;
+
+    from->offset = 0;
+    from->capacity = 0;
+    from->buffer = NULL;
+}
-- 
1.8.3.1