Replace a few bool flags with enums

Functions like copyClosure() had 3 bool arguments, which creates a
severe risk of mixing up arguments.

Also, implement copyClosure() using copyPaths().

22 files changed, 138 insertions, 141 deletions

diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index 7ffbdca7c..8719959f0 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -201,7 +201,7 @@ connected:
             printError("somebody is hogging the upload lock for ‘%s’, continuing...");
         alarm(0);
         signal(SIGALRM, old);
-        copyPaths(store, ref<Store>(sshStore), inputs, false, true);
+        copyPaths(store, ref<Store>(sshStore), inputs, NoRepair, NoCheckSigs);
         uploadLock = -1;
 
         BasicDerivation drv(readDerivation(drvPath));
@@ -219,7 +219,7 @@ connected:
 
         if (!missing.empty()) {
             setenv("NIX_HELD_LOCKS", concatStringsSep(" ", missing).c_str(), 1); /* FIXME: ugly */
-            copyPaths(ref<Store>(sshStore), store, missing, false, true);
+            copyPaths(ref<Store>(sshStore), store, missing, NoRepair, NoCheckSigs);
         }
 
         return;
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 0cdce602d..ca4c9a373 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -293,6 +293,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sWrong(symbols.create("wrong"))
     , sStructuredAttrs(symbols.create("__structuredAttrs"))
     , sBuilder(symbols.create("builder"))
+    , repair(NoRepair)
     , store(store)
     , baseEnv(allocEnv(128))
     , staticBaseEnv(false, 0)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 46d5a1cc8..1e32db1e8 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -14,6 +14,7 @@ namespace nix {
 
 class Store;
 class EvalState;
+enum RepairFlag : bool;
 
 
 typedef void (* PrimOpFun) (EvalState & state, const Pos & pos, Value * * args, Value & v);
@@ -73,7 +74,7 @@ public:
 
     /* If set, force copying files to the Nix store even if they
        already exist there. */
-    bool repair = false;
+    RepairFlag repair;
 
     /* If set, don't allow access to files outside of the Nix search
        path or to environment variables. */
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 46c5aa21b..8ce5f5bbc 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -134,7 +134,7 @@ Path BinaryCacheStore::narInfoFileFor(const Path & storePath)
 }
 
 void BinaryCacheStore::addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-    bool repair, bool dontCheckSigs, std::shared_ptr<FSAccessor> accessor)
+    RepairFlag repair, CheckSigsFlag checkSigs, std::shared_ptr<FSAccessor> accessor)
 {
     if (!repair && isValidPath(info.path)) return;
 
@@ -328,7 +328,7 @@ void BinaryCacheStore::queryPathInfoUncached(const Path & storePath,
 }
 
 Path BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, bool repair)
+    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     // FIXME: some cut&paste from LocalStore::addToStore().
 
@@ -349,13 +349,13 @@ Path BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
     ValidPathInfo info;
     info.path = makeFixedOutputPath(recursive, h, name);
 
-    addToStore(info, sink.s, repair, false, 0);
+    addToStore(info, sink.s, repair, CheckSigs, nullptr);
 
     return info.path;
 }
 
 Path BinaryCacheStore::addTextToStore(const string & name, const string & s,
-    const PathSet & references, bool repair)
+    const PathSet & references, RepairFlag repair)
 {
     ValidPathInfo info;
     info.path = computeStorePathForText(name, s, references);
@@ -364,7 +364,7 @@ Path BinaryCacheStore::addTextToStore(const string & name, const string & s,
     if (repair || !isValidPath(info.path)) {
         StringSink sink;
         dumpString(s, sink);
-        addToStore(info, sink.s, repair, false, 0);
+        addToStore(info, sink.s, repair, CheckSigs, nullptr);
     }
 
     return info.path;
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 87d4aa438..bf5a56ab4 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -85,15 +85,15 @@ public:
     bool wantMassQuery() override { return wantMassQuery_; }
 
     void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-        bool repair, bool dontCheckSigs,
+        RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override;
 
     Path addToStore(const string & name, const Path & srcPath,
         bool recursive, HashType hashAlgo,
-        PathFilter & filter, bool repair) override;
+        PathFilter & filter, RepairFlag repair) override;
 
     Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, bool repair) override;
+        const PathSet & references, RepairFlag repair) override;
 
     void narFromPath(const Path & path, Sink & sink) override;
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index c34083d2e..6c740d99c 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -262,7 +262,7 @@ public:
     GoalPtr makeDerivationGoal(const Path & drvPath, const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
     std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(const Path & drvPath,
         const BasicDerivation & drv, BuildMode buildMode = bmNormal);
-    GoalPtr makeSubstitutionGoal(const Path & storePath, bool repair = false);
+    GoalPtr makeSubstitutionGoal(const Path & storePath, RepairFlag repair = NoRepair);
 
     /* Remove a dead goal. */
     void removeGoal(GoalPtr goal);
@@ -1087,7 +1087,7 @@ void DerivationGoal::haveDerivation()
        them. */
     if (settings.useSubstitutes && drv->substitutesAllowed())
         for (auto & i : invalidOutputs)
-            addWaitee(worker.makeSubstitutionGoal(i, buildMode == bmRepair));
+            addWaitee(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair));
 
     if (waitees.empty()) /* to prevent hang (no wake-up event) */
         outputsSubstituted();
@@ -1195,7 +1195,7 @@ void DerivationGoal::repairClosure()
         printError(format("found corrupted or missing path ‘%1%’ in the output closure of ‘%2%’") % i % drvPath);
         Path drvPath2 = outputsToDrv[i];
         if (drvPath2 == "")
-            addWaitee(worker.makeSubstitutionGoal(i, true));
+            addWaitee(worker.makeSubstitutionGoal(i, Repair));
         else
             addWaitee(worker.makeDerivationGoal(drvPath2, PathSet(), bmRepair));
     }
@@ -3291,7 +3291,7 @@ private:
     std::promise<void> promise;
 
     /* Whether to try to repair a valid path. */
-    bool repair;
+    RepairFlag repair;
 
     /* Location where we're downloading the substitute.  Differs from
        storePath when doing a repair. */
@@ -3301,7 +3301,7 @@ private:
     GoalState state;
 
 public:
-    SubstitutionGoal(const Path & storePath, Worker & worker, bool repair = false);
+    SubstitutionGoal(const Path & storePath, Worker & worker, RepairFlag repair = NoRepair);
     ~SubstitutionGoal();
 
     void timedOut() override { abort(); };
@@ -3337,7 +3337,7 @@ public:
 };
 
 
-SubstitutionGoal::SubstitutionGoal(const Path & storePath, Worker & worker, bool repair)
+SubstitutionGoal::SubstitutionGoal(const Path & storePath, Worker & worker, RepairFlag repair)
     : Goal(worker)
     , hasSubstitute(false)
     , repair(repair)
@@ -3600,7 +3600,7 @@ std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(const Path & drv
 }
 
 
-GoalPtr Worker::makeSubstitutionGoal(const Path & path, bool repair)
+GoalPtr Worker::makeSubstitutionGoal(const Path & path, RepairFlag repair)
 {
     GoalPtr goal = substitutionGoals[path].lock();
     if (!goal) {
@@ -3953,7 +3953,7 @@ void LocalStore::buildPaths(const PathSet & drvPaths, BuildMode buildMode)
         if (isDerivation(i2.first))
             goals.insert(worker.makeDerivationGoal(i2.first, i2.second, buildMode));
         else
-            goals.insert(worker.makeSubstitutionGoal(i, buildMode));
+            goals.insert(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair));
     }
 
     worker.run(goals);
@@ -4011,7 +4011,7 @@ void LocalStore::ensurePath(const Path & path)
 void LocalStore::repairPath(const Path & path)
 {
     Worker worker(*this);
-    GoalPtr goal = worker.makeSubstitutionGoal(path, true);
+    GoalPtr goal = worker.makeSubstitutionGoal(path, Repair);
     Goals goals = {goal};
 
     worker.run(goals);
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 0c6ceb9f6..bb7b8fe62 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -71,7 +71,7 @@ bool BasicDerivation::canBuildLocally() const
 
 
 Path writeDerivation(ref<Store> store,
-    const Derivation & drv, const string & name, bool repair)
+    const Derivation & drv, const string & name, RepairFlag repair)
 {
     PathSet references;
     references.insert(drv.inputSrcs.begin(), drv.inputSrcs.end());
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index 9717a81e4..7b97730d3 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -2,6 +2,7 @@
 
 #include "types.hh"
 #include "hash.hh"
+#include "store-api.hh"
 
 #include <map>
 
@@ -85,7 +86,7 @@ class Store;
 
 /* Write a derivation to the Nix store, and return its path. */
 Path writeDerivation(ref<Store> store,
-    const Derivation & drv, const string & name, bool repair = false);
+    const Derivation & drv, const string & name, RepairFlag repair = NoRepair);
 
 /* Read a derivation from a file. */
 Derivation readDerivation(const Path & drvPath);
diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 33ab1f027..4f3bf2d14 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -631,7 +631,7 @@ Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpa
                 info.narHash = hashString(htSHA256, *sink.s);
                 info.narSize = sink.s->size();
                 info.ca = makeFixedOutputCA(false, hash);
-                store->addToStore(info, sink.s, false, true);
+                store->addToStore(info, sink.s, NoRepair, NoCheckSigs);
                 storePath = info.path;
             }
 
@@ -660,7 +660,7 @@ Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpa
             AutoDelete autoDelete(tmpDir, true);
             // FIXME: this requires GNU tar for decompression.
             runProgram("tar", true, {"xf", storePath, "-C", tmpDir, "--strip-components", "1"});
-            unpackedStorePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, false);
+            unpackedStorePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, NoRepair);
         }
         replaceSymlink(unpackedStorePath, unpackedLink);
         storePath = unpackedStorePath;
diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index 6e8bc692c..1b3a43df3 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -61,7 +61,7 @@ void Store::exportPath(const Path & path, Sink & sink)
     hashAndWriteSink << exportMagic << path << info->references << info->deriver << 0;
 }
 
-Paths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> accessor, bool dontCheckSigs)
+Paths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> accessor, CheckSigsFlag checkSigs)
 {
     Paths res;
     while (true) {
@@ -95,7 +95,7 @@ Paths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> accessor,
         if (readInt(source) == 1)
             readString(source);
 
-        addToStore(info, tee.source.data, false, dontCheckSigs, accessor);
+        addToStore(info, tee.source.data, NoRepair, checkSigs, accessor);
 
         res.push_back(info.path);
     }
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index e09932e3d..a84f85c1b 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -113,7 +113,7 @@ struct LegacySSHStore : public Store
     }
 
     void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-        bool repair, bool dontCheckSigs,
+        RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override
     {
         debug("adding path ‘%s’ to remote host ‘%s’", info.path, host);
@@ -168,11 +168,11 @@ struct LegacySSHStore : public Store
 
     Path addToStore(const string & name, const Path & srcPath,
         bool recursive, HashType hashAlgo,
-        PathFilter & filter, bool repair) override
+        PathFilter & filter, RepairFlag repair) override
     { unsupported(); }
 
     Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, bool repair) override
+        const PathSet & references, RepairFlag repair) override
     { unsupported(); }
 
     BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
@@ -249,7 +249,8 @@ struct LegacySSHStore : public Store
         out.insert(res.begin(), res.end());
     }
 
-    PathSet queryValidPaths(const PathSet & paths, bool maybeSubstitute = false) override
+    PathSet queryValidPaths(const PathSet & paths,
+        SubstituteFlag maybeSubstitute = NoSubstitute) override
     {
         auto conn(connections->get());
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index c76294dcc..a7a94a8b9 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -718,7 +718,7 @@ bool LocalStore::isValidPathUncached(const Path & path)
 }
 
 
-PathSet LocalStore::queryValidPaths(const PathSet & paths, bool maybeSubstitute)
+PathSet LocalStore::queryValidPaths(const PathSet & paths, SubstituteFlag maybeSubstitute)
 {
     PathSet res;
     for (auto & i : paths)
@@ -961,7 +961,7 @@ void LocalStore::invalidatePath(State & state, const Path & path)
 
 
 void LocalStore::addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-    bool repair, bool dontCheckSigs, std::shared_ptr<FSAccessor> accessor)
+    RepairFlag repair, CheckSigsFlag checkSigs, std::shared_ptr<FSAccessor> accessor)
 {
     assert(info.narHash);
 
@@ -974,7 +974,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, const ref<std::string> &
         throw Error("size mismatch importing path ‘%s’; expected %s, got %s",
             info.path, info.narSize, nar->size());
 
-    if (requireSigs && !dontCheckSigs && !info.checkSignatures(*this, publicKeys))
+    if (requireSigs && checkSigs && !info.checkSignatures(*this, publicKeys))
         throw Error("cannot add path ‘%s’ because it lacks a valid signature", info.path);
 
     addTempRoot(info.path);
@@ -1012,7 +1012,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, const ref<std::string> &
 
 
 Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
-    bool recursive, HashType hashAlgo, bool repair)
+    bool recursive, HashType hashAlgo, RepairFlag repair)
 {
     Hash h = hashString(hashAlgo, dump);
 
@@ -1070,7 +1070,7 @@ Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
 
 
 Path LocalStore::addToStore(const string & name, const Path & _srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, bool repair)
+    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     Path srcPath(absPath(_srcPath));
 
@@ -1088,7 +1088,7 @@ Path LocalStore::addToStore(const string & name, const Path & _srcPath,
 
 
 Path LocalStore::addTextToStore(const string & name, const string & s,
-    const PathSet & references, bool repair)
+    const PathSet & references, RepairFlag repair)
 {
     auto hash = hashString(htSHA256, s);
     auto dstPath = makeTextPath(name, hash, references);
@@ -1170,7 +1170,7 @@ void LocalStore::invalidatePathChecked(const Path & path)
 }
 
 
-bool LocalStore::verifyStore(bool checkContents, bool repair)
+bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 {
     printError(format("reading the Nix store..."));
 
@@ -1255,7 +1255,7 @@ bool LocalStore::verifyStore(bool checkContents, bool repair)
 
 
 void LocalStore::verifyPath(const Path & path, const PathSet & store,
-    PathSet & done, PathSet & validPaths, bool repair, bool & errors)
+    PathSet & done, PathSet & validPaths, RepairFlag repair, bool & errors)
 {
     checkInterrupt();
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index f2c40e964..551c6b506 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -98,7 +98,8 @@ public:
 
     bool isValidPathUncached(const Path & path) override;
 
-    PathSet queryValidPaths(const PathSet & paths, bool maybeSubstitute = false) override;
+    PathSet queryValidPaths(const PathSet & paths,
+        SubstituteFlag maybeSubstitute = NoSubstitute) override;
 
     PathSet queryAllValidPaths() override;
 
@@ -122,22 +123,22 @@ public:
         SubstitutablePathInfos & infos) override;
 
     void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-        bool repair, bool dontCheckSigs,
+        RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override;
 
     Path addToStore(const string & name, const Path & srcPath,
         bool recursive, HashType hashAlgo,
-        PathFilter & filter, bool repair) override;
+        PathFilter & filter, RepairFlag repair) override;
 
     /* Like addToStore(), but the contents of the path are contained
        in `dump', which is either a NAR serialisation (if recursive ==
        true) or simply the contents of a regular file (if recursive ==
        false). */
     Path addToStoreFromDump(const string & dump, const string & name,
-        bool recursive = true, HashType hashAlgo = htSHA256, bool repair = false);
+        bool recursive = true, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair);
 
     Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, bool repair) override;
+        const PathSet & references, RepairFlag repair) override;
 
     void buildPaths(const PathSet & paths, BuildMode buildMode) override;
 
@@ -174,7 +175,7 @@ public:
     /* Optimise a single store path. */
     void optimisePath(const Path & path);
 
-    bool verifyStore(bool checkContents, bool repair) override;
+    bool verifyStore(bool checkContents, RepairFlag repair) override;
 
     /* Register the validity of a path, i.e., that `path' exists, that
        the paths referenced by it exists, and in the case of an output
@@ -212,7 +213,7 @@ private:
     void invalidatePathChecked(const Path & path);
 
     void verifyPath(const Path & path, const PathSet & store,
-        PathSet & done, PathSet & validPaths, bool repair, bool & errors);
+        PathSet & done, PathSet & validPaths, RepairFlag repair, bool & errors);
 
     void updatePathInfo(State & state, const ValidPathInfo & info);
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index be8819bbc..7337e406d 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -185,7 +185,7 @@ bool RemoteStore::isValidPathUncached(const Path & path)
 }
 
 
-PathSet RemoteStore::queryValidPaths(const PathSet & paths, bool maybeSubstitute)
+PathSet RemoteStore::queryValidPaths(const PathSet & paths, SubstituteFlag maybeSubstitute)
 {
     auto conn(connections->get());
     if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 12) {
@@ -357,7 +357,7 @@ Path RemoteStore::queryPathFromHashPart(const string & hashPart)
 
 
 void RemoteStore::addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-    bool repair, bool dontCheckSigs, std::shared_ptr<FSAccessor> accessor)
+    RepairFlag repair, CheckSigsFlag checkSigs, std::shared_ptr<FSAccessor> accessor)
 {
     auto conn(connections->get());
 
@@ -390,7 +390,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, const ref<std::string>
                  << info.path << info.deriver << printHash(info.narHash)
                  << info.references << info.registrationTime << info.narSize
                  << info.ultimate << info.sigs << info.ca
-                 << repair << dontCheckSigs;
+                 << repair << !checkSigs;
         conn->to(*nar);
         conn->processStderr();
     }
@@ -398,7 +398,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, const ref<std::string>
 
 
 Path RemoteStore::addToStore(const string & name, const Path & _srcPath,
-    bool recursive, HashType hashAlgo, PathFilter & filter, bool repair)
+    bool recursive, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     if (repair) throw Error("repairing is not supported when building through the Nix daemon");
 
@@ -434,7 +434,7 @@ Path RemoteStore::addToStore(const string & name, const Path & _srcPath,
 
 
 Path RemoteStore::addTextToStore(const string & name, const string & s,
-    const PathSet & references, bool repair)
+    const PathSet & references, RepairFlag repair)
 {
     if (repair) throw Error("repairing is not supported when building through the Nix daemon");
 
@@ -570,7 +570,7 @@ void RemoteStore::optimiseStore()
 }
 
 
-bool RemoteStore::verifyStore(bool checkContents, bool repair)
+bool RemoteStore::verifyStore(bool checkContents, RepairFlag repair)
 {
     auto conn(connections->get());
     conn->to << wopVerifyStore << checkContents << repair;
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index ed430e4ca..e370e4797 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -31,7 +31,8 @@ public:
 
     bool isValidPathUncached(const Path & path) override;
 
-    PathSet queryValidPaths(const PathSet & paths, bool maybeSubstitute = false) override;
+    PathSet queryValidPaths(const PathSet & paths,
+        SubstituteFlag maybeSubstitute = NoSubstitute) override;
 
     PathSet queryAllValidPaths() override;
 
@@ -55,15 +56,15 @@ public:
         SubstitutablePathInfos & infos) override;
 
     void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-        bool repair, bool dontCheckSigs,
+        RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override;
 
     Path addToStore(const string & name, const Path & srcPath,
         bool recursive = true, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, bool repair = false) override;
+        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override;
 
     Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, bool repair = false) override;
+        const PathSet & references, RepairFlag repair) override;
 
     void buildPaths(const PathSet & paths, BuildMode buildMode) override;
 
@@ -84,7 +85,7 @@ public:
 
     void optimiseStore() override;
 
-    bool verifyStore(bool checkContents, bool repair) override;
+    bool verifyStore(bool checkContents, RepairFlag repair) override;
 
     void addSignatures(const Path & storePath, const StringSet & sigs) override;
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 76ed99422..39b946616 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -378,7 +378,7 @@ void Store::queryPathInfo(const Path & storePath,
 }
 
 
-PathSet Store::queryValidPaths(const PathSet & paths, bool maybeSubstitute)
+PathSet Store::queryValidPaths(const PathSet & paths, SubstituteFlag maybeSubstitute)
 {
     struct State
     {
@@ -537,14 +537,14 @@ void Store::buildPaths(const PathSet & paths, BuildMode buildMode)
 
 
 void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
-    const Path & storePath, bool repair, bool dontCheckSigs)
+    const Path & storePath, RepairFlag repair, CheckSigsFlag checkSigs)
 {
     auto info = srcStore->queryPathInfo(storePath);
 
     StringSink sink;
     srcStore->narFromPath({storePath}, sink);
 
-    if (!info->narHash && dontCheckSigs) {
+    if (!info->narHash && !checkSigs) {
         auto info2 = make_ref<ValidPathInfo>(*info);
         info2->narHash = hashString(htSHA256, *sink.s);
         if (!info->narSize) info2->narSize = sink.s->size();
@@ -561,33 +561,47 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
 
     assert(info->narHash);
 
-    dstStore->addToStore(*info, sink.s, repair, dontCheckSigs);
+    dstStore->addToStore(*info, sink.s, repair, checkSigs);
 }
 
 
-void copyClosure(ref<Store> srcStore, ref<Store> dstStore,
-    const PathSet & storePaths, bool repair, bool dontCheckSigs)
+void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const PathSet & storePaths,
+    RepairFlag repair, CheckSigsFlag checkSigs, SubstituteFlag substitute)
 {
-    PathSet closure;
+    PathSet valid = dstStore->queryValidPaths(storePaths, substitute);
+
+    PathSet missing;
     for (auto & path : storePaths)
-        srcStore->computeFSClosure(path, closure);
+        if (!valid.count(path)) missing.insert(path);
 
-    // FIXME: use copyStorePaths()
+    ThreadPool pool;
 
-    PathSet valid = dstStore->queryValidPaths(closure);
+    processGraph<Path>(pool,
+        PathSet(missing.begin(), missing.end()),
 
-    if (valid.size() == closure.size()) return;
+        [&](const Path & storePath) {
+            if (dstStore->isValidPath(storePath)) return PathSet();
+            return srcStore->queryPathInfo(storePath)->references;
+        },
 
-    Paths sorted = srcStore->topoSortPaths(closure);
+        [&](const Path & storePath) {
+            checkInterrupt();
 
-    Paths missing;
-    for (auto i = sorted.rbegin(); i != sorted.rend(); ++i)
-        if (!valid.count(*i)) missing.push_back(*i);
+            if (!dstStore->isValidPath(storePath)) {
+                printError("copying ‘%s’...", storePath);
+                copyStorePath(srcStore, dstStore, storePath, repair, checkSigs);
+            }
+        });
+}
 
-    printMsg(lvlDebug, format("copying %1% missing paths") % missing.size());
 
-    for (auto & i : missing)
-        copyStorePath(srcStore, dstStore, i, repair, dontCheckSigs);
+void copyClosure(ref<Store> srcStore, ref<Store> dstStore,
+    const PathSet & storePaths, RepairFlag repair, CheckSigsFlag checkSigs,
+    SubstituteFlag substitute)
+{
+    PathSet closure;
+    srcStore->computeFSClosure({storePaths}, closure);
+    copyPaths(srcStore, dstStore, closure, repair, checkSigs, substitute);
 }
 
 
@@ -812,45 +826,4 @@ std::list<ref<Store>> getDefaultSubstituters()
 }
 
 
-void copyPaths(ref<Store> from, ref<Store> to, const PathSet & storePaths,
-    bool substitute, bool dontCheckSigs)
-{
-    PathSet valid = to->queryValidPaths(storePaths, substitute);
-
-    PathSet missing;
-    for (auto & path : storePaths)
-        if (!valid.count(path)) missing.insert(path);
-
-    std::string copiedLabel = "copied";
-
-    //logger->setExpected(copiedLabel, missing.size());
-
-    ThreadPool pool;
-
-    processGraph<Path>(pool,
-        PathSet(missing.begin(), missing.end()),
-
-        [&](const Path & storePath) {
-            if (to->isValidPath(storePath)) return PathSet();
-            return from->queryPathInfo(storePath)->references;
-        },
-
-        [&](const Path & storePath) {
-            checkInterrupt();
-
-            if (!to->isValidPath(storePath)) {
-                //Activity act(*logger, lvlInfo, format("copying ‘%s’...") % storePath);
-
-                copyStorePath(from, to, storePath, false, dontCheckSigs);
-
-                //logger->incProgress(copiedLabel);
-            } else
-                ;
-                //logger->incExpected(copiedLabel, -1);
-        });
-
-    pool.process();
-}
-
-
 }
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 929c95a0f..c625a3630 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -32,6 +32,11 @@ class Store;
 class JSONPlaceholder;
 
 
+enum RepairFlag : bool { NoRepair = false, Repair = true };
+enum CheckSigsFlag : bool { NoCheckSigs = false, CheckSigs = true };
+enum SubstituteFlag : bool { NoSubstitute = false, Substitute = true };
+
+
 /* Size of the hash part of store paths, in base-32 characters. */
 const size_t storePathHashLen = 32; // i.e. 160 bits
 
@@ -332,7 +337,7 @@ public:
     /* Query which of the given paths is valid. Optionally, try to
        substitute missing paths. */
     virtual PathSet queryValidPaths(const PathSet & paths,
-        bool maybeSubstitute = false);
+        SubstituteFlag maybeSubstitute = NoSubstitute);
 
     /* Query the set of all valid paths. Note that for some store
        backends, the name part of store paths may be omitted
@@ -392,7 +397,7 @@ public:
 
     /* Import a path into the store. */
     virtual void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
-        bool repair = false, bool dontCheckSigs = false,
+        RepairFlag repair = NoRepair, CheckSigsFlag checkSigs = CheckSigs,
         std::shared_ptr<FSAccessor> accessor = 0) = 0;
 
     /* Copy the contents of a path to the store and register the
@@ -401,12 +406,12 @@ public:
        libutil/archive.hh). */
     virtual Path addToStore(const string & name, const Path & srcPath,
         bool recursive = true, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, bool repair = false) = 0;
+        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) = 0;
 
     /* Like addToStore, but the contents written to the output path is
        a regular file containing the given string. */
     virtual Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, bool repair = false) = 0;
+        const PathSet & references, RepairFlag repair = NoRepair) = 0;
 
     /* Write a NAR dump of a store path. */
     virtual void narFromPath(const Path & path, Sink & sink) = 0;
@@ -496,7 +501,7 @@ public:
 
     /* Check the integrity of the Nix store.  Returns true if errors
        remain. */
-    virtual bool verifyStore(bool checkContents, bool repair) { return false; };
+    virtual bool verifyStore(bool checkContents, RepairFlag repair = NoRepair) { return false; };
 
     /* Return an object to access files in the Nix store. */
     virtual ref<FSAccessor> getFSAccessor() = 0;
@@ -548,7 +553,7 @@ public:
        preloaded into the specified FS accessor to speed up subsequent
        access. */
     Paths importPaths(Source & source, std::shared_ptr<FSAccessor> accessor,
-        bool dontCheckSigs = false);
+        CheckSigsFlag checkSigs = CheckSigs);
 
     struct Stats
     {
@@ -650,12 +655,26 @@ void checkStoreName(const string & name);
 
 /* Copy a path from one store to another. */
 void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
-    const Path & storePath, bool repair = false, bool dontCheckSigs = false);
+    const Path & storePath, RepairFlag repair = NoRepair, CheckSigsFlag checkSigs = CheckSigs);
+
+
+/* Copy store paths from one store to another. The paths may be copied
+   in parallel. They are copied in a topologically sorted order
+   (i.e. if A is a reference of B, then A is copied before B), but
+   the set of store paths is not automatically closed; use
+   copyClosure() for that. */
+void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const PathSet & storePaths,
+    RepairFlag repair = NoRepair,
+    CheckSigsFlag checkSigs = CheckSigs,
+    SubstituteFlag substitute = NoSubstitute);
 
 
 /* Copy the closure of the specified paths from one store to another. */
 void copyClosure(ref<Store> srcStore, ref<Store> dstStore,
-    const PathSet & storePaths, bool repair = false, bool dontCheckSigs = false);
+    const PathSet & storePaths,
+    RepairFlag repair = NoRepair,
+    CheckSigsFlag checkSigs = CheckSigs,
+    SubstituteFlag substitute = NoSubstitute);
 
 
 /* Remove the temporary roots file for this process.  Any temporary
@@ -694,9 +713,6 @@ ref<Store> openStore(const std::string & uri = getEnv("NIX_REMOTE"),
     const Store::Params & extraParams = Store::Params());
 
 
-void copyPaths(ref<Store> from, ref<Store> to, const PathSet & storePaths,
-    bool substitute = false, bool dontCheckSigs = false);
-
 enum StoreType {
     tDaemon,
     tLocal,
diff --git a/src/nix-copy-closure/nix-copy-closure.cc b/src/nix-copy-closure/nix-copy-closure.cc
index dc324abcb..0c69bd413 100755
--- a/src/nix-copy-closure/nix-copy-closure.cc
+++ b/src/nix-copy-closure/nix-copy-closure.cc
@@ -12,7 +12,7 @@ int main(int argc, char ** argv)
         auto toMode = true;
         auto includeOutputs = false;
         auto dryRun = false;
-        auto useSubstitutes = false;
+        auto useSubstitutes = NoSubstitute;
         std::string sshHost;
         PathSet storePaths;
 
@@ -36,7 +36,7 @@ int main(int argc, char ** argv)
             else if (*arg == "--dry-run")
                 dryRun = true;
             else if (*arg == "--use-substitutes" || *arg == "-s")
-                useSubstitutes = true;
+                useSubstitutes = Substitute;
             else if (sshHost.empty())
                 sshHost = *arg;
             else
@@ -58,6 +58,6 @@ int main(int argc, char ** argv)
         PathSet closure;
         from->computeFSClosure(storePaths2, closure, false, includeOutputs);
 
-        copyPaths(from, to, closure, useSubstitutes, true);
+        copyPaths(from, to, closure, NoRepair, NoCheckSigs, useSubstitutes);
     });
 }
diff --git a/src/nix-daemon/nix-daemon.cc b/src/nix-daemon/nix-daemon.cc
index 44127635d..c9c167766 100644
--- a/src/nix-daemon/nix-daemon.cc
+++ b/src/nix-daemon/nix-daemon.cc
@@ -304,7 +304,7 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
         string s = readString(from);
         PathSet refs = readStorePaths<PathSet>(*store, from);
         startWork();
-        Path path = store->addTextToStore(suffix, s, refs, false);
+        Path path = store->addTextToStore(suffix, s, refs, NoRepair);
         stopWork();
         to << path;
         break;
@@ -324,7 +324,8 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
     case wopImportPaths: {
         startWork();
         TunnelSource source(from);
-        Paths paths = store->importPaths(source, 0, trusted);
+        Paths paths = store->importPaths(source, nullptr,
+            trusted ? NoCheckSigs : CheckSigs);
         stopWork();
         to << paths;
         break;
@@ -576,7 +577,7 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
         startWork();
         if (repair && !trusted)
             throw Error("you are not privileged to repair paths");
-        bool errors = store->verifyStore(checkContents, repair);
+        bool errors = store->verifyStore(checkContents, (RepairFlag) repair);
         stopWork();
         to << errors;
         break;
@@ -623,7 +624,8 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
         parseDump(tee, tee.source);
 
         startWork();
-        store->addToStore(info, tee.source.data, repair, dontCheckSigs, nullptr);
+        store->addToStore(info, tee.source.data, (RepairFlag) repair,
+            dontCheckSigs ? NoCheckSigs : CheckSigs, nullptr);
         stopWork();
         break;
     }
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 464bcee4a..10100d6a6 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -1310,7 +1310,7 @@ int main(int argc, char * * argv)
         Strings opFlags, opArgs, searchPath;
         std::map<string, string> autoArgs_;
         Operation op = 0;
-        bool repair = false;
+        RepairFlag repair = NoRepair;
         string file;
 
         Globals globals;
@@ -1372,7 +1372,7 @@ int main(int argc, char * * argv)
             else if (*arg == "--prebuilt-only" || *arg == "-b")
                 globals.prebuiltOnly = true;
             else if (*arg == "--repair")
-                repair = true;
+                repair = Repair;
             else if (*arg != "" && arg->at(0) == '-') {
                 opFlags.push_back(*arg);
                 /* FIXME: hacky */
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 25f0b1bd6..a5d12c146 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -108,7 +108,7 @@ int main(int argc, char * * argv)
         Strings attrPaths;
         bool wantsReadWrite = false;
         std::map<string, string> autoArgs_;
-        bool repair = false;
+        RepairFlag repair = NoRepair;
 
         parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) {
             if (*arg == "--help")
@@ -146,7 +146,7 @@ int main(int argc, char * * argv)
             else if (*arg == "--strict")
                 strict = true;
             else if (*arg == "--repair")
-                repair = true;
+                repair = Repair;
             else if (*arg == "--dry-run")
                 settings.readOnlyMode = true;
             else if (*arg != "" && arg->at(0) == '-')
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 950222812..314c94239 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -677,7 +677,7 @@ static void opImport(Strings opFlags, Strings opArgs)
     if (!opArgs.empty()) throw UsageError("no arguments expected");
 
     FdSource source(STDIN_FILENO);
-    Paths paths = store->importPaths(source, nullptr, true);
+    Paths paths = store->importPaths(source, nullptr, NoCheckSigs);
 
     for (auto & i : paths)
         cout << format("%1%\n") % i << std::flush;
@@ -702,11 +702,11 @@ static void opVerify(Strings opFlags, Strings opArgs)
         throw UsageError("no arguments expected");
 
     bool checkContents = false;
-    bool repair = false;
+    RepairFlag repair = NoRepair;
 
     for (auto & i : opFlags)
         if (i == "--check-contents") checkContents = true;
-        else if (i == "--repair") repair = true;
+        else if (i == "--repair") repair = Repair;
         else throw UsageError(format("unknown flag ‘%1%’") % i);
 
     if (store->verifyStore(checkContents, repair)) {
@@ -871,7 +871,7 @@ static void opServe(Strings opFlags, Strings opArgs)
 
             case cmdImportPaths: {
                 if (!writeAllowed) throw Error("importing paths is not allowed");
-                store->importPaths(in, 0, true); // FIXME: should we skip sig checking?
+                store->importPaths(in, nullptr, NoCheckSigs); // FIXME: should we skip sig checking?
                 out << 1; // indicate success
                 break;
             }