Get data needed by getBuildOutput() from the incoming NAR in a streaming fashion

src/hydra-queue-runner/nar-extractor.hh

@@ -0,0 +1,23 @@
+#pragma once
+
+#include "fs-accessor.hh"
+#include "types.hh"
+#include "serialise.hh"
+#include "hash.hh"
+
+struct NarMemberData
+{
+    nix::FSAccessor::Type type;
+    std::optional<unsigned long long> fileSize;
+    std::optional<std::string> contents;
+    std::optional<nix::Hash> sha256;
+};
+
+typedef std::map<nix::Path, NarMemberData> NarMemberDatas;
+
+/* Read a NAR from a source and get to some info about every file
+   inside the NAR. */
+void extractNarData(
+    nix::Source & source,
+    const nix::Path & prefix,
+    NarMemberDatas & members);