naive lfs support

src/libfetchers/git-utils.cc

@@ -318,6 +318,8 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
 
     std::vector<std::tuple<Submodule, Hash>> getSubmodules(const Hash & rev, bool exportIgnore) override;
 
+    void smudgeLfs() override;
+
     std::string resolveSubmoduleUrl(
         const std::string & url,
         const std::string & base) override
@@ -1007,6 +1009,15 @@ std::vector<std::tuple<GitRepoImpl::Submodule, Hash>> GitRepoImpl::getSubmodules
     return result;
 }
 
+void GitRepoImpl::smudgeLfs() {
+    runProgram(RunOptions{
+            .program = "git",
+            .searchPath = true,
+            .args = { "lfs", "pull" },
+            .chdir = std::make_optional(this->path)
+            });
+}
+
 ref<GitRepo> getTarballCache()
 {
     static auto repoDir = std::filesystem::path(getCacheDir()) / "nix" / "tarball-cache";

src/libfetchers/git-utils.hh

@@ -69,6 +69,8 @@ struct GitRepo
      */
     virtual std::vector<std::tuple<Submodule, Hash>> getSubmodules(const Hash & rev, bool exportIgnore) = 0;
 
+    virtual void smudgeLfs() = 0;
+
     virtual std::string resolveSubmoduleUrl(
         const std::string & url,
         const std::string & base) = 0;

src/libfetchers/git.cc

@@ -381,6 +381,11 @@ struct GitInputScheme : InputScheme
         return maybeGetBoolAttr(input.attrs, "submodules").value_or(false);
     }
 
+    bool getLfsAttr(const Input & input) const
+    {
+        return maybeGetBoolAttr(input.attrs, "lfs").value_or(false);
+    }
+
     bool getExportIgnoreAttr(const Input & input) const
     {
         return maybeGetBoolAttr(input.attrs, "exportIgnore").value_or(false);
@@ -648,6 +653,11 @@ struct GitInputScheme : InputScheme
             }
         }
 
+        if (getLfsAttr(input)) {
+            // urlencoded `?lfs=1` param is set,
+            repo->smudgeLfs();
+        }
+
         assert(!origRev || origRev == rev);
         if (!getShallowAttr(input))
             input.attrs.insert_or_assign("revCount", getIntAttr(infoAttrs, "revCount"));