Merge remote-tracking branch 'upstream/master' into more-rust-ffi

34 files changed, 917 insertions, 159 deletions

diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index 1ca734e75..890310b3e 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -274,7 +274,8 @@ int checkSignature(SV * publicKey_, SV * sig_, char * msg)
 SV * addToStore(char * srcPath, int recursive, char * algo)
     PPCODE:
         try {
-            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, recursive, parseHashType(algo));
+            auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, method, parseHashType(algo));
             XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -285,7 +286,8 @@ SV * makeFixedOutputPath(int recursive, char * algo, char * hash, char * name)
     PPCODE:
         try {
             Hash h(hash, parseHashType(algo));
-            auto path = store()->makeFixedOutputPath(recursive, h, name);
+            auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+            auto path = store()->makeFixedOutputPath(method, h, name);
             XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index d04b4bbbf..157e8ddb4 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -31,7 +31,7 @@ readonly NIX_FIRST_BUILD_UID="30001"
 readonly NIX_ROOT="/nix"
 readonly NIX_EXTRA_CONF=${NIX_EXTRA_CONF:-}
 
-readonly PROFILE_TARGETS=("/etc/bashrc" "/etc/profile.d/nix.sh" "/etc/zshrc")
+readonly PROFILE_TARGETS=("/etc/bashrc" "/etc/profile.d/nix.sh" "/etc/zshenv")
 readonly PROFILE_BACKUP_SUFFIX=".backup-before-nix"
 readonly PROFILE_NIX_FILE="$NIX_ROOT/var/nix/profiles/default/etc/profile.d/nix-daemon.sh"
 
diff --git a/scripts/install.in b/scripts/install.in
index 6709f00d4..1d26c4ff0 100644
--- a/scripts/install.in
+++ b/scripts/install.in
@@ -36,7 +36,9 @@ tarball="$tmpDir/$(basename "$tmpDir/nix-@nixVersion@-$system.tar.xz")"
 
 require_util curl "download the binary tarball"
 require_util tar "unpack the binary tarball"
-require_util xz "unpack the binary tarball"
+if [ "$(uname -s)" != "Darwin" ]; then
+    require_util xz "unpack the binary tarball"
+fi
 
 echo "downloading Nix @nixVersion@ binary tarball for $system from '$url' to '$tmpDir'..."
 curl -L "$url" -o "$tarball" || oops "failed to download '$url'"
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index f2c20dd68..82eb1582e 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1669,7 +1669,7 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
     else {
         auto p = settings.readOnlyMode
             ? store->computeStorePathForPath(std::string(baseNameOf(path)), checkSourcePath(path)).first
-            : store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), true, htSHA256, defaultPathFilter, repair);
+            : store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, repair);
         dstPath = store->printStorePath(p);
         srcToStore.insert_or_assign(path, std::move(p));
         printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 0a4236da4..d458ab272 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -562,7 +562,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
 
     std::optional<std::string> outputHash;
     std::string outputHashAlgo;
-    bool outputHashRecursive = false;
+    auto ingestionMethod = FileIngestionMethod::Flat;
 
     StringSet outputs;
     outputs.insert("out");
@@ -573,8 +573,8 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         vomit("processing attribute '%1%'", key);
 
         auto handleHashMode = [&](const std::string & s) {
-            if (s == "recursive") outputHashRecursive = true;
-            else if (s == "flat") outputHashRecursive = false;
+            if (s == "recursive") ingestionMethod = FileIngestionMethod::Recursive;
+            else if (s == "flat") ingestionMethod = FileIngestionMethod::Flat;
             else throw EvalError("invalid value '%s' for 'outputHashMode' attribute, at %s", s, posDrvName);
         };
 
@@ -721,11 +721,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         HashType ht = outputHashAlgo.empty() ? htUnknown : parseHashType(outputHashAlgo);
         Hash h(*outputHash, ht);
 
-        auto outPath = state.store->makeFixedOutputPath(outputHashRecursive, h, drvName);
+        auto outPath = state.store->makeFixedOutputPath(ingestionMethod, h, drvName);
         if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);
-        drv.outputs.insert_or_assign("out", DerivationOutput(std::move(outPath),
-                (outputHashRecursive ? "r:" : "") + printHashType(h.type),
-                h.to_string(Base16, false)));
+        drv.outputs.insert_or_assign("out", DerivationOutput {
+            std::move(outPath),
+            (ingestionMethod == FileIngestionMethod::Recursive ? "r:" : "")
+                + printHashType(h.type),
+            h.to_string(Base16, false),
+        });
     }
 
     else {
@@ -1039,7 +1042,7 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
 
 
 static void addPath(EvalState & state, const Pos & pos, const string & name, const Path & path_,
-    Value * filterFun, bool recursive, const Hash & expectedHash, Value & v)
+    Value * filterFun, FileIngestionMethod method, const Hash & expectedHash, Value & v)
 {
     const auto path = evalSettings.pureEval && expectedHash ?
         path_ :
@@ -1070,12 +1073,12 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
 
     std::optional<StorePath> expectedStorePath;
     if (expectedHash)
-        expectedStorePath = state.store->makeFixedOutputPath(recursive, expectedHash, name);
+        expectedStorePath = state.store->makeFixedOutputPath(method, expectedHash, name);
     Path dstPath;
     if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
         dstPath = state.store->printStorePath(settings.readOnlyMode
-            ? state.store->computeStorePathForPath(name, path, recursive, htSHA256, filter).first
-            : state.store->addToStore(name, path, recursive, htSHA256, filter, state.repair));
+            ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
+            : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
         if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
             throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
     } else
@@ -1096,7 +1099,7 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
     if (args[0]->type != tLambda)
         throw TypeError(format("first argument in call to 'filterSource' is not a function but %1%, at %2%") % showType(*args[0]) % pos);
 
-    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], true, Hash(), v);
+    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, Hash(), v);
 }
 
 static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1105,7 +1108,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     Path path;
     string name;
     Value * filterFun = nullptr;
-    auto recursive = true;
+    auto method = FileIngestionMethod::Recursive;
     Hash expectedHash;
 
     for (auto & attr : *args[0]->attrs) {
@@ -1121,7 +1124,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
             state.forceValue(*attr.value, pos);
             filterFun = attr.value;
         } else if (n == "recursive")
-            recursive = state.forceBool(*attr.value, *attr.pos);
+            method = FileIngestionMethod { state.forceBool(*attr.value, *attr.pos) };
         else if (n == "sha256")
             expectedHash = Hash(state.forceStringNoCtx(*attr.value, *attr.pos), htSHA256);
         else
@@ -1132,7 +1135,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     if (name.empty())
         name = baseNameOf(path);
 
-    addPath(state, pos, name, path, filterFun, recursive, expectedHash, v);
+    addPath(state, pos, name, path, filterFun, method, expectedHash, v);
 }
 
 
diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 7c18cf67f..17cc60228 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -195,7 +195,7 @@ struct GitInput : Input
                     return files.count(file);
                 };
 
-                auto storePath = store->addToStore("source", actualUrl, true, htSHA256, filter);
+                auto storePath = store->addToStore("source", actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
 
                 auto tree = Tree {
                     .actualPath = store->printStorePath(storePath),
@@ -347,7 +347,7 @@ struct GitInput : Input
             unpackTarfile(*source, tmpDir);
         }
 
-        auto storePath = store->addToStore(name, tmpDir, true, htSHA256, filter);
+        auto storePath = store->addToStore(name, tmpDir, FileIngestionMethod::Recursive, htSHA256, filter);
 
         auto lastModified = std::stoull(runProgram("git", true, { "-C", repoDir, "log", "-1", "--format=%ct", input->rev->gitRev() }));
 
diff --git a/src/libfetchers/mercurial.cc b/src/libfetchers/mercurial.cc
index 1d6571571..2e0d4bf4d 100644
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@@ -114,7 +114,7 @@ struct MercurialInput : Input
                     return files.count(file);
                 };
 
-                auto storePath = store->addToStore("source", actualUrl, true, htSHA256, filter);
+                auto storePath = store->addToStore("source", actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
 
                 return {Tree {
                     .actualPath = store->printStorePath(storePath),
diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 695525b31..bf2b2a5ff 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -67,10 +67,10 @@ DownloadFileResult downloadFile(
         StringSink sink;
         dumpString(*res.data, sink);
         auto hash = hashString(htSHA256, *res.data);
-        ValidPathInfo info(store->makeFixedOutputPath(false, hash, name));
+        ValidPathInfo info(store->makeFixedOutputPath(FileIngestionMethod::Flat, hash, name));
         info.narHash = hashString(htSHA256, *sink.s);
         info.narSize = sink.s->size();
-        info.ca = makeFixedOutputCA(false, hash);
+        info.ca = makeFixedOutputCA(FileIngestionMethod::Flat, hash);
         store->addToStore(info, sink.s, NoRepair, NoCheckSigs);
         storePath = std::move(info.path);
     }
@@ -141,7 +141,7 @@ Tree downloadTarball(
             throw nix::Error("tarball '%s' contains an unexpected number of top-level files", url);
         auto topDir = tmpDir + "/" + members.begin()->name;
         lastModified = lstat(topDir).st_mtime;
-        unpackedStorePath = store->addToStore(name, topDir, true, htSHA256, defaultPathFilter, NoRepair);
+        unpackedStorePath = store->addToStore(name, topDir, FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, NoRepair);
     }
 
     Attrs infoAttrs({
diff --git a/src/libfetchers/tree-info.cc b/src/libfetchers/tree-info.cc
index 5788e94a1..b2d8cfc8d 100644
--- a/src/libfetchers/tree-info.cc
+++ b/src/libfetchers/tree-info.cc
@@ -8,7 +8,7 @@ namespace nix::fetchers {
 StorePath TreeInfo::computeStorePath(Store & store) const
 {
     assert(narHash);
-    return store.makeFixedOutputPath(true, narHash, "source");
+    return store.makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, "source");
 }
 
 }
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 3a2d84861..f13736c58 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -327,7 +327,7 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
 }
 
 StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     // FIXME: some cut&paste from LocalStore::addToStore().
 
@@ -336,7 +336,7 @@ StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath
        small files. */
     StringSink sink;
     Hash h;
-    if (recursive) {
+    if (method == FileIngestionMethod::Recursive) {
         dumpPath(srcPath, sink, filter);
         h = hashString(hashAlgo, *sink.s);
     } else {
@@ -345,7 +345,7 @@ StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath
         h = hashString(hashAlgo, s);
     }
 
-    ValidPathInfo info(makeFixedOutputPath(recursive, h, name));
+    ValidPathInfo info(makeFixedOutputPath(method, h, name));
 
     addToStore(info, sink.s, repair, CheckSigs, nullptr);
 
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index aa13c1cb4..4ff5609ed 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -79,7 +79,7 @@ public:
         std::shared_ptr<FSAccessor> accessor) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive, HashType hashAlgo,
+        FileIngestionMethod method, HashType hashAlgo,
         PathFilter & filter, RepairFlag repair) override;
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index a2b16f95c..f5c132a83 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2734,7 +2734,7 @@ struct RestrictedStore : public LocalFSStore
     { throw Error("queryPathFromHashPart"); }
 
     StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive = true, HashType hashAlgo = htSHA256,
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
         PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override
     { throw Error("addToStore"); }
 
@@ -2747,9 +2747,9 @@ struct RestrictedStore : public LocalFSStore
     }
 
     StorePath addToStoreFromDump(const string & dump, const string & name,
-        bool recursive = true, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override
     {
-        auto path = next->addToStoreFromDump(dump, name, recursive, hashAlgo, repair);
+        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair);
         goal.addDependency(path);
         return path;
     }
@@ -3692,10 +3692,10 @@ void DerivationGoal::registerOutputs()
 
         if (fixedOutput) {
 
-            bool recursive; Hash h;
-            i.second.parseHashInfo(recursive, h);
+            FileIngestionMethod outputHashMode; Hash h;
+            i.second.parseHashInfo(outputHashMode, h);
 
-            if (!recursive) {
+            if (outputHashMode == FileIngestionMethod::Flat) {
                 /* The output path should be a regular file without execute permission. */
                 if (!S_ISREG(st.st_mode) || (st.st_mode & S_IXUSR) != 0)
                     throw BuildError(
@@ -3705,9 +3705,11 @@ void DerivationGoal::registerOutputs()
 
             /* Check the hash. In hash mode, move the path produced by
                the derivation to its content-addressed location. */
-            Hash h2 = recursive ? hashPath(h.type, actualPath).first : hashFile(h.type, actualPath);
+            Hash h2 = outputHashMode == FileIngestionMethod::Recursive
+                ? hashPath(h.type, actualPath).first
+                : hashFile(h.type, actualPath);
 
-            auto dest = worker.store.makeFixedOutputPath(recursive, h2, i.second.path.name());
+            auto dest = worker.store.makeFixedOutputPath(outputHashMode, h2, i.second.path.name());
 
             if (h != h2) {
 
@@ -3736,7 +3738,7 @@ void DerivationGoal::registerOutputs()
             else
                 assert(worker.store.parseStorePath(path) == dest);
 
-            ca = makeFixedOutputCA(recursive, h2);
+            ca = makeFixedOutputCA(outputHashMode, h2);
         }
 
         /* Get rid of all weird permissions.  This also checks that
@@ -3957,7 +3959,9 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
 
                 auto spec = parseReferenceSpecifiers(worker.store, *drv, *value);
 
-                auto used = recursive ? cloneStorePathSet(getClosure(info.path).first) : cloneStorePathSet(info.references);
+                auto used = recursive
+                    ? cloneStorePathSet(getClosure(info.path).first)
+                    : cloneStorePathSet(info.references);
 
                 if (recursive && checks.ignoreSelfRefs)
                     used.erase(info.path);
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 8e9f9d71b..f1afdff69 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -355,20 +355,24 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddToStore: {
-        bool fixed, recursive;
         std::string s, baseName;
-        from >> baseName >> fixed /* obsolete */ >> recursive >> s;
-        /* Compatibility hack. */
-        if (!fixed) {
-            s = "sha256";
-            recursive = true;
+        FileIngestionMethod method;
+        {
+            bool fixed, recursive;
+            from >> baseName >> fixed /* obsolete */ >> recursive >> s;
+            method = FileIngestionMethod { recursive };
+            /* Compatibility hack. */
+            if (!fixed) {
+                s = "sha256";
+                method = FileIngestionMethod::Recursive;
+            }
         }
         HashType hashAlgo = parseHashType(s);
 
         TeeSource savedNAR(from);
         RetrieveRegularNARSink savedRegular;
 
-        if (recursive) {
+        if (method == FileIngestionMethod::Recursive) {
             /* Get the entire NAR dump from the client and save it to
                a string so that we can pass it to
                addToStoreFromDump(). */
@@ -380,7 +384,11 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         if (!savedRegular.regular) throw Error("regular file expected");
 
-        auto path = store->addToStoreFromDump(recursive ? *savedNAR.data : savedRegular.s, baseName, recursive, hashAlgo);
+        auto path = store->addToStoreFromDump(
+            method == FileIngestionMethod::Recursive ? *savedNAR.data : savedRegular.s,
+            baseName,
+            method,
+            hashAlgo);
         logger->stopWork();
 
         to << store->printStorePath(path);
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 0067032af..c68e7b16b 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -9,13 +9,13 @@
 namespace nix {
 
 
-void DerivationOutput::parseHashInfo(bool & recursive, Hash & hash) const
+void DerivationOutput::parseHashInfo(FileIngestionMethod & recursive, Hash & hash) const
 {
-    recursive = false;
+    recursive = FileIngestionMethod::Flat;
     string algo = hashAlgo;
 
     if (string(algo, 0, 2) == "r:") {
-        recursive = true;
+        recursive = FileIngestionMethod::Recursive;
         algo = string(algo, 2);
     }
 
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index f010318ce..ea517a78c 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -25,7 +25,7 @@ struct DerivationOutput
     DerivationOutput(const DerivationOutput &) = default;
     DerivationOutput(DerivationOutput &&) = default;
     DerivationOutput & operator = (const DerivationOutput &) = default;
-    void parseHashInfo(bool & recursive, Hash & hash) const;
+    void parseHashInfo(FileIngestionMethod & recursive, Hash & hash) const;
 };
 
 typedef std::map<string, DerivationOutput> DerivationOutputs;
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 458266be0..af20d389b 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -195,7 +195,7 @@ struct LegacySSHStore : public Store
     { unsupported("queryPathFromHashPart"); }
 
     StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive, HashType hashAlgo,
+        FileIngestionMethod method, HashType hashAlgo,
         PathFilter & filter, RepairFlag repair) override
     { unsupported("addToStore"); }
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index ae7513ad8..80851b591 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -557,10 +557,10 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
         if (out == drv.outputs.end())
             throw Error("derivation '%s' does not have an output named 'out'", printStorePath(drvPath));
 
-        bool recursive; Hash h;
-        out->second.parseHashInfo(recursive, h);
+        FileIngestionMethod method; Hash h;
+        out->second.parseHashInfo(method, h);
 
-        check(makeFixedOutputPath(recursive, h, drvName), out->second.path, "out");
+        check(makeFixedOutputPath(method, h, drvName), out->second.path, "out");
     }
 
     else {
@@ -1043,11 +1043,11 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
 
 StorePath LocalStore::addToStoreFromDump(const string & dump, const string & name,
-    bool recursive, HashType hashAlgo, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
 {
     Hash h = hashString(hashAlgo, dump);
 
-    auto dstPath = makeFixedOutputPath(recursive, h, name);
+    auto dstPath = makeFixedOutputPath(method, h, name);
 
     addTempRoot(dstPath);
 
@@ -1067,7 +1067,7 @@ StorePath LocalStore::addToStoreFromDump(const string & dump, const string & nam
 
             autoGC();
 
-            if (recursive) {
+            if (method == FileIngestionMethod::Recursive) {
                 StringSource source(dump);
                 restorePath(realPath, source);
             } else
@@ -1080,7 +1080,7 @@ StorePath LocalStore::addToStoreFromDump(const string & dump, const string & nam
                above (if called with recursive == true and hashAlgo ==
                sha256); otherwise, compute it here. */
             HashResult hash;
-            if (recursive) {
+            if (method == FileIngestionMethod::Recursive) {
                 hash.first = hashAlgo == htSHA256 ? h : hashString(htSHA256, dump);
                 hash.second = dump.size();
             } else
@@ -1091,7 +1091,7 @@ StorePath LocalStore::addToStoreFromDump(const string & dump, const string & nam
             ValidPathInfo info(dstPath.clone());
             info.narHash = hash.first;
             info.narSize = hash.second;
-            info.ca = makeFixedOutputCA(recursive, h);
+            info.ca = makeFixedOutputCA(method, h);
             registerValidPath(info);
         }
 
@@ -1103,7 +1103,7 @@ StorePath LocalStore::addToStoreFromDump(const string & dump, const string & nam
 
 
 StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     Path srcPath(absPath(_srcPath));
 
@@ -1111,12 +1111,12 @@ StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
        method for very large paths, but `copyPath' is mainly used for
        small files. */
     StringSink sink;
-    if (recursive)
+    if (method == FileIngestionMethod::Recursive)
         dumpPath(srcPath, sink, filter);
     else
         sink.s = make_ref<std::string>(readFile(srcPath));
 
-    return addToStoreFromDump(*sink.s, name, recursive, hashAlgo, repair);
+    return addToStoreFromDump(*sink.s, name, method, hashAlgo, repair);
 }
 
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 16aeab0ad..c1e75390c 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -149,7 +149,7 @@ public:
         std::shared_ptr<FSAccessor> accessor) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive, HashType hashAlgo,
+        FileIngestionMethod method, HashType hashAlgo,
         PathFilter & filter, RepairFlag repair) override;
 
     /* Like addToStore(), but the contents of the path are contained
@@ -157,7 +157,7 @@ public:
        true) or simply the contents of a regular file (if recursive ==
        false). */
     StorePath addToStoreFromDump(const string & dump, const string & name,
-        bool recursive = true, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override;
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override;
 
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
diff --git a/src/libstore/path.hh b/src/libstore/path.hh
index 186976855..f3ed6ca39 100644
--- a/src/libstore/path.hh
+++ b/src/libstore/path.hh
@@ -87,6 +87,11 @@ const size_t storePathHashLen = 32; // i.e. 160 bits
 /* Extension of derivations in the Nix store. */
 const std::string drvExtension = ".drv";
 
+enum struct FileIngestionMethod : uint8_t {
+    Flat = false,
+    Recursive = true
+};
+
 struct StorePathWithOutputs
 {
     StorePath path;
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 8c55da268..5c36693e6 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -484,7 +484,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
 
 
 StorePath RemoteStore::addToStore(const string & name, const Path & _srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     if (repair) throw Error("repairing is not supported when building through the Nix daemon");
 
@@ -492,10 +492,12 @@ StorePath RemoteStore::addToStore(const string & name, const Path & _srcPath,
 
     Path srcPath(absPath(_srcPath));
 
-    conn->to << wopAddToStore << name
-       << ((hashAlgo == htSHA256 && recursive) ? 0 : 1) /* backwards compatibility hack */
-       << (recursive ? 1 : 0)
-       << printHashType(hashAlgo);
+    conn->to
+        << wopAddToStore
+        << name
+        << ((hashAlgo == htSHA256 && method == FileIngestionMethod::Recursive) ? 0 : 1) /* backwards compatibility hack */
+        << (method == FileIngestionMethod::Recursive ? 1 : 0)
+        << printHashType(hashAlgo);
 
     try {
         conn->to.written = 0;
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index f301a97d8..3c86b4524 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -65,7 +65,7 @@ public:
         std::shared_ptr<FSAccessor> accessor) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive = true, HashType hashAlgo = htSHA256,
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
         PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override;
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 91ba64cfc..472595b5a 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -172,19 +172,22 @@ static std::string makeType(
 
 
 StorePath Store::makeFixedOutputPath(
-    bool recursive,
+    FileIngestionMethod recursive,
     const Hash & hash,
     std::string_view name,
     const StorePathSet & references,
     bool hasSelfReference) const
 {
-    if (hash.type == htSHA256 && recursive) {
+    if (hash.type == htSHA256 && recursive == FileIngestionMethod::Recursive) {
         return makeStorePath(makeType(*this, "source", references, hasSelfReference), hash, name);
     } else {
         assert(references.empty());
-        return makeStorePath("output:out", hashString(htSHA256,
-                "fixed:out:" + (recursive ? (string) "r:" : "") +
-                hash.to_string(Base16) + ":"), name);
+        return makeStorePath("output:out",
+            hashString(htSHA256,
+                "fixed:out:"
+                + (recursive == FileIngestionMethod::Recursive ? (string) "r:" : "")
+                + hash.to_string(Base16) + ":"),
+            name);
     }
 }
 
@@ -201,10 +204,12 @@ StorePath Store::makeTextPath(std::string_view name, const Hash & hash,
 
 
 std::pair<StorePath, Hash> Store::computeStorePathForPath(std::string_view name,
-    const Path & srcPath, bool recursive, HashType hashAlgo, PathFilter & filter) const
+    const Path & srcPath, FileIngestionMethod method, HashType hashAlgo, PathFilter & filter) const
 {
-    Hash h = recursive ? hashPath(hashAlgo, srcPath, filter).first : hashFile(hashAlgo, srcPath);
-    return std::make_pair(makeFixedOutputPath(recursive, h, name), h);
+    Hash h = method == FileIngestionMethod::Recursive
+        ? hashPath(hashAlgo, srcPath, filter).first
+        : hashFile(hashAlgo, srcPath);
+    return std::make_pair(makeFixedOutputPath(method, h, name), h);
 }
 
 
@@ -767,8 +772,8 @@ bool ValidPathInfo::isContentAddressed(const Store & store) const
     }
 
     else if (hasPrefix(ca, "fixed:")) {
-        bool recursive = ca.compare(6, 2, "r:") == 0;
-        Hash hash(std::string(ca, recursive ? 8 : 6));
+        FileIngestionMethod recursive { ca.compare(6, 2, "r:") == 0 };
+        Hash hash(std::string(ca, recursive == FileIngestionMethod::Recursive ? 8 : 6));
         auto refs = cloneStorePathSet(references);
         bool hasSelfReference = false;
         if (refs.count(path)) {
@@ -812,9 +817,11 @@ Strings ValidPathInfo::shortRefs() const
 }
 
 
-std::string makeFixedOutputCA(bool recursive, const Hash & hash)
+std::string makeFixedOutputCA(FileIngestionMethod recursive, const Hash & hash)
 {
-    return "fixed:" + (recursive ? (std::string) "r:" : "") + hash.to_string();
+    return "fixed:"
+        + (recursive == FileIngestionMethod::Recursive ? (std::string) "r:" : "")
+        + hash.to_string();
 }
 
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 7832aed23..cd9e97ed9 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -44,7 +44,6 @@ enum CheckSigsFlag : bool { NoCheckSigs = false, CheckSigs = true };
 enum SubstituteFlag : bool { NoSubstitute = false, Substitute = true };
 enum AllowInvalidFlag : bool { DisallowInvalid = false, AllowInvalid = true };
 
-
 /* Magic header of exportPath() output (obsolete). */
 const uint32_t exportMagic = 0x4558494e;
 
@@ -348,7 +347,7 @@ public:
     StorePath makeOutputPath(const string & id,
         const Hash & hash, std::string_view name) const;
 
-    StorePath makeFixedOutputPath(bool recursive,
+    StorePath makeFixedOutputPath(FileIngestionMethod method,
         const Hash & hash, std::string_view name,
         const StorePathSet & references = {},
         bool hasSelfReference = false) const;
@@ -360,7 +359,7 @@ public:
        store path to which srcPath is to be copied.  Returns the store
        path and the cryptographic hash of the contents of srcPath. */
     std::pair<StorePath, Hash> computeStorePathForPath(std::string_view name,
-        const Path & srcPath, bool recursive = true,
+        const Path & srcPath, FileIngestionMethod method = FileIngestionMethod::Recursive,
         HashType hashAlgo = htSHA256, PathFilter & filter = defaultPathFilter) const;
 
     /* Preparatory part of addTextToStore().
@@ -464,12 +463,12 @@ public:
        The function object `filter' can be used to exclude files (see
        libutil/archive.hh). */
     virtual StorePath addToStore(const string & name, const Path & srcPath,
-        bool recursive = true, HashType hashAlgo = htSHA256,
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
         PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) = 0;
 
     // FIXME: remove?
     virtual StorePath addToStoreFromDump(const string & dump, const string & name,
-        bool recursive = true, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair)
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair)
     {
         throw Error("addToStoreFromDump() is not supported by this store");
     }
@@ -852,7 +851,7 @@ std::optional<ValidPathInfo> decodeValidPathInfo(
 
 /* Compute the content-addressability assertion (ValidPathInfo::ca)
    for paths created by makeFixedOutputPath() / addToStore(). */
-std::string makeFixedOutputCA(bool recursive, const Hash & hash);
+std::string makeFixedOutputCA(FileIngestionMethod method, const Hash & hash);
 
 
 /* Split URI into protocol+hierarchy part and its parameter set. */
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index f03e444ec..8fc700a2b 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -65,60 +65,63 @@ void Config::getSettings(std::map<std::string, SettingInfo> & res, bool override
             res.emplace(opt.first, SettingInfo{opt.second.setting->to_string(), opt.second.setting->description});
 }
 
-void AbstractConfig::applyConfigFile(const Path & path)
-{
-    try {
-        string contents = readFile(path);
-
-        unsigned int pos = 0;
-
-        while (pos < contents.size()) {
-            string line;
-            while (pos < contents.size() && contents[pos] != '\n')
-                line += contents[pos++];
-            pos++;
-
-            string::size_type hash = line.find('#');
-            if (hash != string::npos)
-                line = string(line, 0, hash);
-
-            vector<string> tokens = tokenizeString<vector<string> >(line);
-            if (tokens.empty()) continue;
+void AbstractConfig::applyConfig(const std::string & contents, const std::string & path) {
+    unsigned int pos = 0;
+
+    while (pos < contents.size()) {
+        string line;
+        while (pos < contents.size() && contents[pos] != '\n')
+            line += contents[pos++];
+        pos++;
+
+        string::size_type hash = line.find('#');
+        if (hash != string::npos)
+            line = string(line, 0, hash);
+
+        vector<string> tokens = tokenizeString<vector<string> >(line);
+        if (tokens.empty()) continue;
+
+        if (tokens.size() < 2)
+            throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
+
+        auto include = false;
+        auto ignoreMissing = false;
+        if (tokens[0] == "include")
+            include = true;
+        else if (tokens[0] == "!include") {
+            include = true;
+            ignoreMissing = true;
+        }
 
-            if (tokens.size() < 2)
+        if (include) {
+            if (tokens.size() != 2)
                 throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
-
-            auto include = false;
-            auto ignoreMissing = false;
-            if (tokens[0] == "include")
-                include = true;
-            else if (tokens[0] == "!include") {
-                include = true;
-                ignoreMissing = true;
+            auto p = absPath(tokens[1], dirOf(path));
+            if (pathExists(p)) {
+                applyConfigFile(p);
+            } else if (!ignoreMissing) {
+                throw Error("file '%1%' included from '%2%' not found", p, path);
             }
+            continue;
+        }
 
-            if (include) {
-                if (tokens.size() != 2)
-                    throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
-                auto p = absPath(tokens[1], dirOf(path));
-                if (pathExists(p)) {
-                    applyConfigFile(p);
-                } else if (!ignoreMissing) {
-                    throw Error("file '%1%' included from '%2%' not found", p, path);
-                }
-                continue;
-            }
+        if (tokens[1] != "=")
+            throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
 
-            if (tokens[1] != "=")
-                throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
+        string name = tokens[0];
 
-            string name = tokens[0];
+        vector<string>::iterator i = tokens.begin();
+        advance(i, 2);
 
-            vector<string>::iterator i = tokens.begin();
-            advance(i, 2);
+        set(name, concatStringsSep(" ", Strings(i, tokens.end()))); // FIXME: slow
+    };
+}
 
-            set(name, concatStringsSep(" ", Strings(i, tokens.end()))); // FIXME: slow
-        };
+void AbstractConfig::applyConfigFile(const Path & path)
+{
+    try {
+        string contents = readFile(path);
+        applyConfig(contents, path);
     } catch (SysError &) { }
 }
 
diff --git a/src/libutil/config.hh b/src/libutil/config.hh
index 7ea78fdaf..5c7a70a2e 100644
--- a/src/libutil/config.hh
+++ b/src/libutil/config.hh
@@ -7,6 +7,38 @@
 
 namespace nix {
 
+/**
+ * The Config class provides Nix runtime configurations.
+ *
+ * What is a Configuration?
+ *   A collection of uniquely named Settings.
+ *
+ * What is a Setting?
+ *   Each property that you can set in a configuration corresponds to a
+ *   `Setting`. A setting records value and description of a property
+ *   with a default and optional aliases.
+ *
+ * A valid configuration consists of settings that are registered to a
+ * `Config` object instance:
+ *
+ *   Config config;
+ *   Setting<std::string> systemSetting{&config, "x86_64-linux", "system", "the current system"};
+ *
+ * The above creates a `Config` object and registers a setting called "system"
+ * via the variable `systemSetting` with it. The setting defaults to the string
+ * "x86_64-linux", it's description is "the current system". All of the
+ * registered settings can then be accessed as shown below:
+ *
+ *   std::map<std::string, Config::SettingInfo> settings;
+ *   config.getSettings(settings);
+ *   config["system"].description == "the current system"
+ *   config["system"].value == "x86_64-linux"
+ *
+ *
+ * The above retrieves all currently known settings from the `Config` object
+ * and adds them to the `settings` map.
+ */
+
 class Args;
 class AbstractSetting;
 class JSONPlaceholder;
@@ -23,6 +55,10 @@ protected:
 
 public:
 
+    /**
+     * Sets the value referenced by `name` to `value`. Returns true if the
+     * setting is known, false otherwise.
+     */
     virtual bool set(const std::string & name, const std::string & value) = 0;
 
     struct SettingInfo
@@ -31,18 +67,52 @@ public:
         std::string description;
     };
 
+    /**
+     * Adds the currently known settings to the given result map `res`.
+     * - res: map to store settings in
+     * - overridenOnly: when set to true only overridden settings will be added to `res`
+     */
     virtual void getSettings(std::map<std::string, SettingInfo> & res, bool overridenOnly = false) = 0;
 
+    /**
+     * Parses the configuration in `contents` and applies it
+     * - contents: configuration contents to be parsed and applied
+     * - path: location of the configuration file
+     */
+    void applyConfig(const std::string & contents, const std::string & path = "<unknown>");
+
+    /**
+     * Applies a nix configuration file
+     * - path: the location of the config file to apply
+     */
     void applyConfigFile(const Path & path);
 
+    /**
+     * Resets the `overridden` flag of all Settings
+     */
     virtual void resetOverriden() = 0;
 
+    /**
+     * Outputs all settings to JSON
+     * - out: JSONObject to write the configuration to
+     */
     virtual void toJSON(JSONObject & out) = 0;
 
+    /**
+     * Converts settings to `Args` to be used on the command line interface
+     * - args: args to write to
+     * - category: category of the settings
+     */
     virtual void convertToArgs(Args & args, const std::string & category) = 0;
 
+    /**
+     * Logs a warning for each unregistered setting
+     */
     void warnUnknownSettings();
 
+    /**
+     * Re-applies all previously attempted changes to unknown settings
+     */
     void reapplyUnknownSettings();
 };
 
diff --git a/src/libutil/tests/config.cc b/src/libutil/tests/config.cc
new file mode 100644
index 000000000..74c59fd31
--- /dev/null
+++ b/src/libutil/tests/config.cc
@@ -0,0 +1,264 @@
+#include "json.hh"
+#include "config.hh"
+#include "args.hh"
+
+#include <sstream>
+#include <gtest/gtest.h>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * Config
+     * --------------------------------------------------------------------------*/
+
+    TEST(Config, setUndefinedSetting) {
+        Config config;
+        ASSERT_EQ(config.set("undefined-key", "value"), false);
+    }
+
+    TEST(Config, setDefinedSetting) {
+        Config config;
+        std::string value;
+        Setting<std::string> foo{&config, value, "name-of-the-setting", "description"};
+        ASSERT_EQ(config.set("name-of-the-setting", "value"), true);
+    }
+
+    TEST(Config, getDefinedSetting) {
+        Config config;
+        std::string value;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> foo{&config, value, "name-of-the-setting", "description"};
+
+        config.getSettings(settings, /* overridenOnly = */ false);
+        const auto iter = settings.find("name-of-the-setting");
+        ASSERT_NE(iter, settings.end());
+        ASSERT_EQ(iter->second.value, "");
+        ASSERT_EQ(iter->second.description, "description");
+    }
+
+    TEST(Config, getDefinedOverridenSettingNotSet) {
+        Config config;
+        std::string value;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> foo{&config, value, "name-of-the-setting", "description"};
+
+        config.getSettings(settings, /* overridenOnly = */ true);
+        const auto e = settings.find("name-of-the-setting");
+        ASSERT_EQ(e, settings.end());
+    }
+
+    TEST(Config, getDefinedSettingSet1) {
+        Config config;
+        std::string value;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> setting{&config, value, "name-of-the-setting", "description"};
+
+        setting.assign("value");
+
+        config.getSettings(settings, /* overridenOnly = */ false);
+        const auto iter = settings.find("name-of-the-setting");
+        ASSERT_NE(iter, settings.end());
+        ASSERT_EQ(iter->second.value, "value");
+        ASSERT_EQ(iter->second.description, "description");
+    }
+
+    TEST(Config, getDefinedSettingSet2) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+
+        ASSERT_TRUE(config.set("name-of-the-setting", "value"));
+
+        config.getSettings(settings, /* overridenOnly = */ false);
+        const auto e = settings.find("name-of-the-setting");
+        ASSERT_NE(e, settings.end());
+        ASSERT_EQ(e->second.value, "value");
+        ASSERT_EQ(e->second.description, "description");
+    }
+
+    TEST(Config, addSetting) {
+        class TestSetting : public AbstractSetting {
+            public:
+            TestSetting() : AbstractSetting("test", "test", {}) {}
+            void set(const std::string & value) {}
+            std::string to_string() const { return {}; }
+        };
+
+        Config config;
+        TestSetting setting;
+
+        ASSERT_FALSE(config.set("test", "value"));
+        config.addSetting(&setting);
+        ASSERT_TRUE(config.set("test", "value"));
+    }
+
+    TEST(Config, withInitialValue) {
+        const StringMap initials = {
+            { "key", "value" },
+        };
+        Config config(initials);
+
+        {
+            std::map<std::string, Config::SettingInfo> settings;
+            config.getSettings(settings, /* overridenOnly = */ false);
+            ASSERT_EQ(settings.find("key"), settings.end());
+        }
+
+        Setting<std::string> setting{&config, "default-value", "key", "description"};
+
+        {
+            std::map<std::string, Config::SettingInfo> settings;
+            config.getSettings(settings, /* overridenOnly = */ false);
+            ASSERT_EQ(settings["key"].value, "value");
+        }
+    }
+
+    TEST(Config, resetOverriden) {
+        Config config;
+        config.resetOverriden();
+    }
+
+    TEST(Config, resetOverridenWithSetting) {
+        Config config;
+        Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+
+        {
+            std::map<std::string, Config::SettingInfo> settings;
+
+            setting.set("foo");
+            ASSERT_EQ(setting.get(), "foo");
+            config.getSettings(settings, /* overridenOnly = */ true);
+            ASSERT_TRUE(settings.empty());
+        }
+
+        {
+            std::map<std::string, Config::SettingInfo> settings;
+
+            setting.override("bar");
+            ASSERT_TRUE(setting.overriden);
+            ASSERT_EQ(setting.get(), "bar");
+            config.getSettings(settings, /* overridenOnly = */ true);
+            ASSERT_FALSE(settings.empty());
+        }
+
+        {
+            std::map<std::string, Config::SettingInfo> settings;
+
+            config.resetOverriden();
+            ASSERT_FALSE(setting.overriden);
+            config.getSettings(settings, /* overridenOnly = */ true);
+            ASSERT_TRUE(settings.empty());
+        }
+    }
+
+    TEST(Config, toJSONOnEmptyConfig) {
+        std::stringstream out;
+        { // Scoped to force the destructor of JSONObject to write the final `}`
+            JSONObject obj(out);
+            Config config;
+            config.toJSON(obj);
+        }
+
+        ASSERT_EQ(out.str(), "{}");
+    }
+
+    TEST(Config, toJSONOnNonEmptyConfig) {
+        std::stringstream out;
+        { // Scoped to force the destructor of JSONObject to write the final `}`
+            JSONObject obj(out);
+
+            Config config;
+            std::map<std::string, Config::SettingInfo> settings;
+            Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+            setting.assign("value");
+
+            config.toJSON(obj);
+        }
+        ASSERT_EQ(out.str(), R"#({"name-of-the-setting":{"description":"description","value":"value"}})#");
+    }
+
+    TEST(Config, setSettingAlias) {
+        Config config;
+        Setting<std::string> setting{&config, "", "some-int", "best number", { "another-int" }};
+        ASSERT_TRUE(config.set("some-int", "1"));
+        ASSERT_EQ(setting.get(), "1");
+        ASSERT_TRUE(config.set("another-int", "2"));
+        ASSERT_EQ(setting.get(), "2");
+        ASSERT_TRUE(config.set("some-int", "3"));
+        ASSERT_EQ(setting.get(), "3");
+    }
+
+    /* FIXME: The reapplyUnknownSettings method doesn't seem to do anything
+     * useful (these days).  Whenever we add a new setting to Config the
+     * unknown settings are always considered.  In which case is this function
+     * actually useful? Is there some way to register a Setting without calling
+     * addSetting? */
+    TEST(Config, DISABLED_reapplyUnknownSettings) {
+        Config config;
+        ASSERT_FALSE(config.set("name-of-the-setting", "unknownvalue"));
+        Setting<std::string> setting{&config, "default", "name-of-the-setting", "description"};
+        ASSERT_EQ(setting.get(), "default");
+        config.reapplyUnknownSettings();
+        ASSERT_EQ(setting.get(), "unknownvalue");
+    }
+
+    TEST(Config, applyConfigEmpty) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        config.applyConfig("");
+        config.getSettings(settings);
+        ASSERT_TRUE(settings.empty());
+    }
+
+    TEST(Config, applyConfigEmptyWithComment) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        config.applyConfig("# just a comment");
+        config.getSettings(settings);
+        ASSERT_TRUE(settings.empty());
+    }
+
+    TEST(Config, applyConfigAssignment) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+        config.applyConfig(
+            "name-of-the-setting = value-from-file #useful comment\n"
+            "# name-of-the-setting = foo\n"
+        );
+        config.getSettings(settings);
+        ASSERT_FALSE(settings.empty());
+        ASSERT_EQ(settings["name-of-the-setting"].value, "value-from-file");
+    }
+
+    TEST(Config, applyConfigWithReassignedSetting) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+        config.applyConfig(
+            "name-of-the-setting = first-value\n"
+            "name-of-the-setting = second-value\n"
+        );
+        config.getSettings(settings);
+        ASSERT_FALSE(settings.empty());
+        ASSERT_EQ(settings["name-of-the-setting"].value, "second-value");
+    }
+
+    TEST(Config, applyConfigFailsOnMissingIncludes) {
+        Config config;
+        std::map<std::string, Config::SettingInfo> settings;
+        Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
+
+        ASSERT_THROW(config.applyConfig(
+            "name-of-the-setting = value-from-file\n"
+            "# name-of-the-setting = foo\n"
+            "include /nix/store/does/not/exist.nix"
+        ), Error);
+    }
+
+    TEST(Config, applyConfigInvalidThrows) {
+        Config config;
+        ASSERT_THROW(config.applyConfig("value == key"), UsageError);
+        ASSERT_THROW(config.applyConfig("value "), UsageError);
+    }
+}
diff --git a/src/libutil/tests/hash.cc b/src/libutil/tests/hash.cc
new file mode 100644
index 000000000..7cb439817
--- /dev/null
+++ b/src/libutil/tests/hash.cc
@@ -0,0 +1,80 @@
+#include "hash.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * hashString
+     * --------------------------------------------------------------------------*/
+
+    TEST(hashString, testKnownMD5Hashes1) {
+        // values taken from: https://tools.ietf.org/html/rfc1321
+        auto s1 = "";
+        auto hash = hashString(HashType::htMD5, s1);
+        ASSERT_EQ(hash.to_string(Base::Base16), "md5:d41d8cd98f00b204e9800998ecf8427e");
+    }
+
+    TEST(hashString, testKnownMD5Hashes2) {
+        // values taken from: https://tools.ietf.org/html/rfc1321
+        auto s2 = "abc";
+        auto hash = hashString(HashType::htMD5, s2);
+        ASSERT_EQ(hash.to_string(Base::Base16), "md5:900150983cd24fb0d6963f7d28e17f72");
+    }
+
+    TEST(hashString, testKnownSHA1Hashes1) {
+        // values taken from: https://tools.ietf.org/html/rfc3174
+        auto s = "abc";
+        auto hash = hashString(HashType::htSHA1, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:a9993e364706816aba3e25717850c26c9cd0d89d");
+    }
+
+    TEST(hashString, testKnownSHA1Hashes2) {
+        // values taken from: https://tools.ietf.org/html/rfc3174
+        auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
+        auto hash = hashString(HashType::htSHA1, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:84983e441c3bd26ebaae4aa1f95129e5e54670f1");
+    }
+
+    TEST(hashString, testKnownSHA256Hashes1) {
+        // values taken from: https://tools.ietf.org/html/rfc4634
+        auto s = "abc";
+
+        auto hash = hashString(HashType::htSHA256, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),
+                "sha256:ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad");
+    }
+
+    TEST(hashString, testKnownSHA256Hashes2) {
+        // values taken from: https://tools.ietf.org/html/rfc4634
+        auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
+        auto hash = hashString(HashType::htSHA256, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),
+                "sha256:248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1");
+    }
+
+    TEST(hashString, testKnownSHA512Hashes1) {
+        // values taken from: https://tools.ietf.org/html/rfc4634
+        auto s = "abc";
+        auto hash = hashString(HashType::htSHA512, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),
+                "sha512:ddaf35a193617abacc417349ae20413112e6fa4e89a9"
+                "7ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd"
+                "454d4423643ce80e2a9ac94fa54ca49f");
+    }
+
+    TEST(hashString, testKnownSHA512Hashes2) {
+        // values taken from: https://tools.ietf.org/html/rfc4634
+        auto s = "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu";
+
+        auto hash = hashString(HashType::htSHA512, s);
+        ASSERT_EQ(hash.to_string(Base::Base16),
+                "sha512:8e959b75dae313da8cf4f72814fc143f8f7779c6eb9f7fa1"
+                "7299aeadb6889018501d289e4900f7e4331b99dec4b5433a"
+                "c7d329eeb6dd26545e96e55b874be909");
+    }
+
+    TEST(hashString, hashingWithUnknownAlgoExits) {
+        auto s = "unknown";
+        ASSERT_DEATH(hashString(HashType::htUnknown, s), "");
+    }
+}
diff --git a/src/libutil/tests/json.cc b/src/libutil/tests/json.cc
new file mode 100644
index 000000000..dea73f53a
--- /dev/null
+++ b/src/libutil/tests/json.cc
@@ -0,0 +1,193 @@
+#include "json.hh"
+#include <gtest/gtest.h>
+#include <sstream>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * toJSON
+     * --------------------------------------------------------------------------*/
+
+    TEST(toJSON, quotesCharPtr) {
+        const char* input = "test";
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "\"test\"");
+    }
+
+    TEST(toJSON, quotesStdString) {
+        std::string input = "test";
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "\"test\"");
+    }
+
+    TEST(toJSON, convertsNullptrtoNull) {
+        auto input = nullptr;
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "null");
+    }
+
+    TEST(toJSON, convertsNullToNull) {
+        const char* input = 0;
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "null");
+    }
+
+
+    TEST(toJSON, convertsFloat) {
+        auto input = 1.024f;
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "1.024");
+    }
+
+    TEST(toJSON, convertsDouble) {
+        const double input = 1.024;
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "1.024");
+    }
+
+    TEST(toJSON, convertsBool) {
+        auto input = false;
+        std::stringstream out;
+        toJSON(out, input);
+
+        ASSERT_EQ(out.str(), "false");
+    }
+
+    TEST(toJSON, quotesTab) {
+        std::stringstream out;
+        toJSON(out, "\t");
+
+        ASSERT_EQ(out.str(), "\"\\t\"");
+    }
+
+    TEST(toJSON, quotesNewline) {
+        std::stringstream out;
+        toJSON(out, "\n");
+
+        ASSERT_EQ(out.str(), "\"\\n\"");
+    }
+
+    TEST(toJSON, quotesCreturn) {
+        std::stringstream out;
+        toJSON(out, "\r");
+
+        ASSERT_EQ(out.str(), "\"\\r\"");
+    }
+
+    TEST(toJSON, quotesCreturnNewLine) {
+        std::stringstream out;
+        toJSON(out, "\r\n");
+
+        ASSERT_EQ(out.str(), "\"\\r\\n\"");
+    }
+
+    TEST(toJSON, quotesDoublequotes) {
+        std::stringstream out;
+        toJSON(out, "\"");
+
+        ASSERT_EQ(out.str(), "\"\\\"\"");
+    }
+
+    TEST(toJSON, substringEscape) {
+        std::stringstream out;
+        const char *s = "foo\t";
+        toJSON(out, s+3, s + strlen(s));
+
+        ASSERT_EQ(out.str(), "\"\\t\"");
+    }
+
+    /* ----------------------------------------------------------------------------
+     * JSONObject
+     * --------------------------------------------------------------------------*/
+
+    TEST(JSONObject, emptyObject) {
+        std::stringstream out;
+        {
+            JSONObject t(out);
+        }
+        ASSERT_EQ(out.str(), "{}");
+    }
+
+    TEST(JSONObject, objectWithList) {
+        std::stringstream out;
+        {
+            JSONObject t(out);
+            auto l = t.list("list");
+            l.elem("element");
+        }
+        ASSERT_EQ(out.str(), R"#({"list":["element"]})#");
+    }
+
+    TEST(JSONObject, objectWithListIndent) {
+        std::stringstream out;
+        {
+            JSONObject t(out, true);
+            auto l = t.list("list");
+            l.elem("element");
+        }
+        ASSERT_EQ(out.str(),
+R"#({
+  "list": [
+    "element"
+  ]
+})#");
+    }
+
+    TEST(JSONObject, objectWithPlaceholderAndList) {
+        std::stringstream out;
+        {
+            JSONObject t(out);
+            auto l = t.placeholder("list");
+            l.list().elem("element");
+        }
+
+        ASSERT_EQ(out.str(), R"#({"list":["element"]})#");
+    }
+
+    TEST(JSONObject, objectWithPlaceholderAndObject) {
+        std::stringstream out;
+        {
+            JSONObject t(out);
+            auto l = t.placeholder("object");
+            l.object().attr("key", "value");
+        }
+
+        ASSERT_EQ(out.str(), R"#({"object":{"key":"value"}})#");
+    }
+
+    /* ----------------------------------------------------------------------------
+     * JSONList
+     * --------------------------------------------------------------------------*/
+
+    TEST(JSONList, empty) {
+        std::stringstream out;
+        {
+            JSONList l(out);
+        }
+        ASSERT_EQ(out.str(), R"#([])#");
+    }
+
+    TEST(JSONList, withElements) {
+        std::stringstream out;
+        {
+            JSONList l(out);
+            l.elem("one");
+            l.object();
+            l.placeholder().write("three");
+        }
+        ASSERT_EQ(out.str(), R"#(["one",{},"three"])#");
+    }
+}
+
diff --git a/src/libutil/tests/xml-writer.cc b/src/libutil/tests/xml-writer.cc
new file mode 100644
index 000000000..adcde25c9
--- /dev/null
+++ b/src/libutil/tests/xml-writer.cc
@@ -0,0 +1,105 @@
+#include "xml-writer.hh"
+#include <gtest/gtest.h>
+#include <sstream>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * XMLWriter
+     * --------------------------------------------------------------------------*/
+
+    TEST(XMLWriter, emptyObject) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n");
+    }
+
+    TEST(XMLWriter, objectWithEmptyElement) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            t.openElement("foobar");
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar></foobar>");
+    }
+
+    TEST(XMLWriter, objectWithElementWithAttrs) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            XMLAttrs attrs = {
+                { "foo", "bar" }
+            };
+            t.openElement("foobar", attrs);
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar foo=\"bar\"></foobar>");
+    }
+
+    TEST(XMLWriter, objectWithElementWithEmptyAttrs) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            XMLAttrs attrs = {};
+            t.openElement("foobar", attrs);
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar></foobar>");
+    }
+
+    TEST(XMLWriter, objectWithElementWithAttrsEscaping) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            XMLAttrs attrs = {
+                { "<key>", "<value>" }
+            };
+            t.openElement("foobar", attrs);
+        }
+
+        // XXX: While "<value>" is escaped, "<key>" isn't which I think is a bug.
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar <key>=\"&lt;value&gt;\"></foobar>");
+    }
+
+    TEST(XMLWriter, objectWithElementWithAttrsIndented) {
+        std::stringstream out;
+        {
+            XMLWriter t(true, out);
+            XMLAttrs attrs = {
+                { "foo", "bar" }
+            };
+            t.openElement("foobar", attrs);
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar foo=\"bar\">\n</foobar>\n");
+    }
+
+    TEST(XMLWriter, writeEmptyElement) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            t.writeEmptyElement("foobar");
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar />");
+    }
+
+    TEST(XMLWriter, writeEmptyElementWithAttributes) {
+        std::stringstream out;
+        {
+            XMLWriter t(false, out);
+            XMLAttrs attrs = {
+                { "foo", "bar" }
+            };
+            t.writeEmptyElement("foobar", attrs);
+
+        }
+
+        ASSERT_EQ(out.str(), "<?xml version='1.0' encoding='utf-8'?>\n<foobar foo=\"bar\" />");
+    }
+
+}
diff --git a/src/nix-prefetch-url/nix-prefetch-url.cc b/src/nix-prefetch-url/nix-prefetch-url.cc
index 748554b9c..5a686c8cd 100644
--- a/src/nix-prefetch-url/nix-prefetch-url.cc
+++ b/src/nix-prefetch-url/nix-prefetch-url.cc
@@ -159,7 +159,8 @@ static int _main(int argc, char * * argv)
         std::optional<StorePath> storePath;
         if (args.size() == 2) {
             expectedHash = Hash(args[1], ht);
-            storePath = store->makeFixedOutputPath(unpack, expectedHash, name);
+            const auto recursive = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+            storePath = store->makeFixedOutputPath(recursive, expectedHash, name);
             if (store->isValidPath(*storePath))
                 hash = expectedHash;
             else
@@ -208,13 +209,15 @@ static int _main(int argc, char * * argv)
             if (expectedHash != Hash(ht) && expectedHash != hash)
                 throw Error(format("hash mismatch for '%1%'") % uri);
 
+            const auto recursive = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+
             /* Copy the file to the Nix store. FIXME: if RemoteStore
                implemented addToStoreFromDump() and downloadFile()
                supported a sink, we could stream the download directly
                into the Nix store. */
-            storePath = store->addToStore(name, tmpFile, unpack, ht);
+            storePath = store->addToStore(name, tmpFile, recursive, ht);
 
-            assert(*storePath == store->makeFixedOutputPath(unpack, hash, name));
+            assert(*storePath == store->makeFixedOutputPath(recursive, hash, name));
         }
 
         stopProgressBar();
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index fcc00175a..3a3060ad8 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -174,10 +174,10 @@ static void opAdd(Strings opFlags, Strings opArgs)
    store. */
 static void opAddFixed(Strings opFlags, Strings opArgs)
 {
-    bool recursive = false;
+    auto recursive = FileIngestionMethod::Flat;
 
     for (auto & i : opFlags)
-        if (i == "--recursive") recursive = true;
+        if (i == "--recursive") recursive = FileIngestionMethod::Recursive;
         else throw UsageError(format("unknown flag '%1%'") % i);
 
     if (opArgs.empty())
@@ -194,10 +194,10 @@ static void opAddFixed(Strings opFlags, Strings opArgs)
 /* Hack to support caching in `nix-prefetch-url'. */
 static void opPrintFixedPath(Strings opFlags, Strings opArgs)
 {
-    bool recursive = false;
+    auto recursive = FileIngestionMethod::Flat;
 
     for (auto i : opFlags)
-        if (i == "--recursive") recursive = true;
+        if (i == "--recursive") recursive = FileIngestionMethod::Recursive;
         else throw UsageError(format("unknown flag '%1%'") % i);
 
     if (opArgs.size() != 3)
diff --git a/src/nix/add-to-store.cc b/src/nix/add-to-store.cc
index 1d298903b..4b4ba81cb 100644
--- a/src/nix/add-to-store.cc
+++ b/src/nix/add-to-store.cc
@@ -45,10 +45,10 @@ struct CmdAddToStore : MixDryRun, StoreCommand
 
         auto narHash = hashString(htSHA256, *sink.s);
 
-        ValidPathInfo info(store->makeFixedOutputPath(true, narHash, *namePart));
+        ValidPathInfo info(store->makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, *namePart));
         info.narHash = narHash;
         info.narSize = sink.s->size();
-        info.ca = makeFixedOutputCA(true, info.narHash);
+        info.ca = makeFixedOutputCA(FileIngestionMethod::Recursive, info.narHash);
 
         if (!dryRun)
             store->addToStore(info, sink.s);
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 366314227..0a7c343d0 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -9,15 +9,14 @@ using namespace nix;
 
 struct CmdHash : Command
 {
-    enum Mode { mFile, mPath };
-    Mode mode;
+    FileIngestionMethod mode;
     Base base = SRI;
     bool truncate = false;
     HashType ht = htSHA256;
     std::vector<std::string> paths;
     std::optional<std::string> modulus;
 
-    CmdHash(Mode mode) : mode(mode)
+    CmdHash(FileIngestionMethod mode) : mode(mode)
     {
         mkFlag(0, "sri", "print hash in SRI format", &base, SRI);
         mkFlag(0, "base64", "print hash in base-64", &base, Base64);
@@ -36,9 +35,14 @@ struct CmdHash : Command
 
     std::string description() override
     {
-        return mode == mFile
-            ? "print cryptographic hash of a regular file"
-            : "print cryptographic hash of the NAR serialisation of a path";
+        const char* d;
+        switch (mode) {
+        case FileIngestionMethod::Flat:
+            d = "print cryptographic hash of a regular file";
+        case FileIngestionMethod::Recursive:
+            d = "print cryptographic hash of the NAR serialisation of a path";
+        };
+        return d;
     }
 
     Category category() override { return catUtility; }
@@ -53,10 +57,14 @@ struct CmdHash : Command
             else
                 hashSink = std::make_unique<HashSink>(ht);
 
-            if (mode == mFile)
+            switch (mode) {
+            case FileIngestionMethod::Flat:
                 readFile(path, *hashSink);
-            else
+                break;
+            case FileIngestionMethod::Recursive:
                 dumpPath(path, *hashSink);
+                break;
+            }
 
             Hash h = hashSink->finish().first;
             if (truncate && h.hashSize > 20) h = compressHash(h, 20);
@@ -65,8 +73,8 @@ struct CmdHash : Command
     }
 };
 
-static RegisterCommand r1("hash-file", [](){ return make_ref<CmdHash>(CmdHash::mFile); });
-static RegisterCommand r2("hash-path", [](){ return make_ref<CmdHash>(CmdHash::mPath); });
+static RegisterCommand r1("hash-file", [](){ return make_ref<CmdHash>(FileIngestionMethod::Flat); });
+static RegisterCommand r2("hash-path", [](){ return make_ref<CmdHash>(FileIngestionMethod::Recursive); });
 
 struct CmdToBase : Command
 {
@@ -137,7 +145,7 @@ static int compatNixHash(int argc, char * * argv)
     });
 
     if (op == opHash) {
-        CmdHash cmd(flat ? CmdHash::mFile : CmdHash::mPath);
+        CmdHash cmd(flat ? FileIngestionMethod::Flat : FileIngestionMethod::Recursive);
         cmd.ht = ht;
         cmd.base = base32 ? Base32 : Base16;
         cmd.truncate = truncate;
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
index 8803461f4..3e7ff544d 100644
--- a/src/nix/make-content-addressable.cc
+++ b/src/nix/make-content-addressable.cc
@@ -77,12 +77,12 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
 
             auto narHash = hashModuloSink.finish().first;
 
-            ValidPathInfo info(store->makeFixedOutputPath(true, narHash, path.name(), references, hasSelfReference));
+            ValidPathInfo info(store->makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, path.name(), references, hasSelfReference));
             info.references = std::move(references);
             if (hasSelfReference) info.references.insert(info.path.clone());
             info.narHash = narHash;
             info.narSize = sink.s->size();
-            info.ca = makeFixedOutputCA(true, info.narHash);
+            info.ca = makeFixedOutputCA(FileIngestionMethod::Recursive, info.narHash);
 
             if (!json)
                 printError("rewrote '%s' to '%s'", pathS, store->printStorePath(info.path));