1 files changed, 56 insertions, 1 deletions

diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index d1a16b6ba..16f3476c2 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -201,6 +201,62 @@ static DefaultStackAllocator defaultAllocatorSingleton;
 StackAllocator *StackAllocator::defaultAllocator = &defaultAllocatorSingleton;
 
 
+std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
+{
+    struct SourceToSink : FinishSink
+    {
+        typedef boost::coroutines2::coroutine<bool> coro_t;
+
+        std::function<void(Source &)> fun;
+        std::optional<coro_t::push_type> coro;
+
+        SourceToSink(std::function<void(Source &)> fun) : fun(fun)
+        {
+        }
+
+        std::string_view cur;
+
+        void operator () (std::string_view in) override
+        {
+            if (in.empty()) return;
+            cur = in;
+
+            if (!coro)
+                coro = coro_t::push_type(VirtualStackAllocator{}, [&](coro_t::pull_type & yield) {
+                    LambdaSource source([&](char *out, size_t out_len) {
+                        if (cur.empty()) {
+                            yield();
+                            if (yield.get()) {
+                                return (size_t)0;
+                            }
+                        }
+
+                        size_t n = std::min(cur.size(), out_len);
+                        memcpy(out, cur.data(), n);
+                        cur.remove_prefix(n);
+                        return n;
+                    });
+                    fun(source);
+                });
+
+            if (!*coro) { abort(); }
+
+            if (!cur.empty()) (*coro)(false);
+        }
+
+        void finish() override
+        {
+            if (!coro) return;
+            if (!*coro) abort();
+            (*coro)(true);
+            if (*coro) abort();
+        }
+    };
+
+    return std::make_unique<SourceToSink>(fun);
+}
+
+
 std::unique_ptr<Source> sinkToSource(
     std::function<void(Sink &)> fun,
     std::function<void()> eof)
@@ -212,7 +268,6 @@ std::unique_ptr<Source> sinkToSource(
         std::function<void(Sink &)> fun;
         std::function<void()> eof;
         std::optional<coro_t::pull_type> coro;
-        bool started = false;
 
         SinkToSource(std::function<void(Sink &)> fun, std::function<void()> eof)
             : fun(fun), eof(eof)