Remove fetchers::Tree and move tarball-related stuff into its own header

src/libfetchers/tarball.hh

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "types.hh"
+#include "path.hh"
+
+#include <optional>
+
+namespace nix {
+class Store;
+}
+
+namespace nix::fetchers {
+
+struct DownloadFileResult
+{
+    StorePath storePath;
+    std::string etag;
+    std::string effectiveUrl;
+    std::optional<std::string> immutableUrl;
+};
+
+DownloadFileResult downloadFile(
+    ref<Store> store,
+    const std::string & url,
+    const std::string & name,
+    bool locked,
+    const Headers & headers = {});
+
+struct DownloadTarballResult
+{
+    StorePath storePath;
+    time_t lastModified;
+    std::optional<std::string> immutableUrl;
+};
+
+DownloadTarballResult downloadTarball(
+    ref<Store> store,
+    const std::string & url,
+    const std::string & name,
+    bool locked,
+    const Headers & headers = {});
+
+}