Merge remote-tracking branch 'upstream/master' into single-ca-drv-build

1 files changed, 11 insertions, 0 deletions

diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 3650857aa..5309828bc 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -231,6 +231,17 @@ struct SizedSource : Source
     }
 };
 
+/* A sink that that just counts the number of bytes given to it */
+struct LengthSink : Sink
+{
+    uint64_t length = 0;
+
+    virtual void operator () (const unsigned char * _, size_t len)
+    {
+        length += len;
+    }
+};
+
 /* Convert a function into a sink. */
 struct LambdaSink : Sink
 {