Merge remote-tracking branch 'origin/master' into markdown

2020-07-31 16:07:04 +02:00 · 2020-07-31 16:07:04 +02:00 · bf290c2306
parent 2ae9ac2369 0604cfd0eb
commit bf290c2306
38 changed files with 475 additions and 197 deletions
--- a/doc/manual/src/command-ref/conf-file.md
+++ b/doc/manual/src/command-ref/conf-file.md
@ -206,26 +206,6 @@ The following settings are currently available:
    robustness in case of system crashes, but reduces performance. The
    default is `true`.

-  - `hashed-mirrors`  
-    A list of web servers used by `builtins.fetchurl` to obtain files by
-    hash. The default is `http://tarballs.nixos.org/`. Given a hash type
-    *ht* and a base-16 hash *h*, Nix will try to download the file from
-    `hashed-mirror/ht/h`. This allows files to be downloaded even if
-    they have disappeared from their original URI. For example, given
-    the default mirror `http://tarballs.nixos.org/`, when building the
-    derivation
-
-    ```nix
-    builtins.fetchurl {
-      url = "https://example.org/foo-1.2.3.tar.xz";
-      sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae";
-    }
-    ```
-    
-    Nix will attempt to download this file from
-    `http://tarballs.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae`
-    first. If it is not available there, if will try the original URI.
-
  - `http-connections`  
    The maximum number of parallel TCP connections used to fetch files
    from binary caches and by other downloads. It defaults to 25. 0
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@ -33,7 +33,7 @@ std::string escapeUri(std::string uri)

 static string currentLoad;

-static AutoCloseFD openSlotLock(const Machine & m, unsigned long long slot)
+static AutoCloseFD openSlotLock(const Machine & m, uint64_t slot)
 {
    return openLockFile(fmt("%s/%s-%d", currentLoad, escapeUri(m.storeUri), slot), true);
 }
@ -119,7 +119,7 @@ static int _main(int argc, char * * argv)
                bool rightType = false;

                Machine * bestMachine = nullptr;
-                unsigned long long bestLoad = 0;
+                uint64_t bestLoad = 0;
                for (auto & m : machines) {
                    debug("considering building on remote machine '%s'", m.storeUri);

@ -130,8 +130,8 @@ static int _main(int argc, char * * argv)
                        m.mandatoryMet(requiredFeatures)) {
                        rightType = true;
                        AutoCloseFD free;
-                        unsigned long long load = 0;
-                        for (unsigned long long slot = 0; slot < m.maxJobs; ++slot) {
+                        uint64_t load = 0;
+                        for (uint64_t slot = 0; slot < m.maxJobs; ++slot) {
                            auto slotLock = openSlotLock(m, slot);
                            if (lockFile(slotLock.get(), ltWrite, false)) {
                                if (!free) {
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@ -65,7 +65,7 @@ void EvalState::realiseContext(const PathSet & context)

    /* For performance, prefetch all substitute info. */
    StorePathSet willBuild, willSubstitute, unknown;
-    unsigned long long downloadSize, narSize;
+    uint64_t downloadSize, narSize;
    store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);

    store->buildPaths(drvs);
@ -1199,7 +1199,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
    string name;
    Value * filterFun = nullptr;
    auto method = FileIngestionMethod::Recursive;
-    Hash expectedHash(htSHA256);
+    std::optional<Hash> expectedHash;

    for (auto & attr : *args[0]->attrs) {
        const string & n(attr.name);
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@ -36,7 +36,7 @@ void printGCWarning()

 void printMissing(ref<Store> store, const std::vector<StorePathWithOutputs> & paths, Verbosity lvl)
 {
-    unsigned long long downloadSize, narSize;
+    uint64_t downloadSize, narSize;
    StorePathSet willBuild, willSubstitute, unknown;
    store->queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
    printMissing(store, willBuild, willSubstitute, unknown, downloadSize, narSize, lvl);
@ -45,7 +45,7 @@ void printMissing(ref<Store> store, const std::vector<StorePathWithOutputs> & pa

 void printMissing(ref<Store> store, const StorePathSet & willBuild,
    const StorePathSet & willSubstitute, const StorePathSet & unknown,
-    unsigned long long downloadSize, unsigned long long narSize, Verbosity lvl)
+    uint64_t downloadSize, uint64_t narSize, Verbosity lvl)
 {
    if (!willBuild.empty()) {
        if (willBuild.size() == 1)
@ -386,7 +386,7 @@ RunPager::~RunPager()
 }


-string showBytes(unsigned long long bytes)
+string showBytes(uint64_t bytes)
 {
    return (format("%.2f MiB") % (bytes / (1024.0 * 1024.0))).str();
 }
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@ -47,7 +47,7 @@ void printMissing(

 void printMissing(ref<Store> store, const StorePathSet & willBuild,
    const StorePathSet & willSubstitute, const StorePathSet & unknown,
-    unsigned long long downloadSize, unsigned long long narSize, Verbosity lvl = lvlInfo);
+    uint64_t downloadSize, uint64_t narSize, Verbosity lvl = lvlInfo);

 string getArg(const string & opt,
    Strings::iterator & i, const Strings::iterator & end);
@ -110,7 +110,7 @@ extern volatile ::sig_atomic_t blockInt;

 /* GC helpers. */

-string showBytes(unsigned long long bytes);
+string showBytes(uint64_t bytes);

 struct GCResults;

--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@ -297,7 +297,7 @@ public:
    GoalPtr makeDerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
    std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(const StorePath & drvPath,
        const BasicDerivation & drv, BuildMode buildMode = bmNormal);
-    GoalPtr makeSubstitutionGoal(const StorePath & storePath, RepairFlag repair = NoRepair);
+    GoalPtr makeSubstitutionGoal(const StorePath & storePath, RepairFlag repair = NoRepair, std::optional<ContentAddress> ca = std::nullopt);

    /* Remove a dead goal. */
    void removeGoal(GoalPtr goal);
@ -1206,7 +1206,7 @@ void DerivationGoal::haveDerivation()
       them. */
    if (settings.useSubstitutes && parsedDrv->substitutesAllowed())
        for (auto & i : invalidOutputs)
-            addWaitee(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair));
+            addWaitee(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair, getDerivationCA(*drv)));

    if (waitees.empty()) /* to prevent hang (no wake-up event) */
        outputsSubstituted();
@ -1646,13 +1646,13 @@ void DerivationGoal::buildDone()
               So instead, check if the disk is (nearly) full now.  If
               so, we don't mark this build as a permanent failure. */
 #if HAVE_STATVFS
-            unsigned long long required = 8ULL * 1024 * 1024; // FIXME: make configurable
+            uint64_t required = 8ULL * 1024 * 1024; // FIXME: make configurable
            struct statvfs st;
            if (statvfs(worker.store.realStoreDir.c_str(), &st) == 0 &&
-                (unsigned long long) st.f_bavail * st.f_bsize < required)
+                (uint64_t) st.f_bavail * st.f_bsize < required)
                diskFull = true;
            if (statvfs(tmpDir.c_str(), &st) == 0 &&
-                (unsigned long long) st.f_bavail * st.f_bsize < required)
+                (uint64_t) st.f_bavail * st.f_bsize < required)
                diskFull = true;
 #endif

@ -2851,7 +2851,7 @@ struct RestrictedStore : public LocalFSStore

    void queryMissing(const std::vector<StorePathWithOutputs> & targets,
        StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
-        unsigned long long & downloadSize, unsigned long long & narSize) override
+        uint64_t & downloadSize, uint64_t & narSize) override
    {
        /* This is slightly impure since it leaks information to the
           client about what paths will be built/substituted or are
@ -4276,6 +4276,10 @@ private:
    /* The store path that should be realised through a substitute. */
    StorePath storePath;

+    /* The path the substituter refers to the path as. This will be
+     * different when the stores have different names. */
+    std::optional<StorePath> subPath;
+
    /* The remaining substituters. */
    std::list<ref<Store>> subs;

@ -4309,8 +4313,11 @@ private:
    typedef void (SubstitutionGoal::*GoalState)();
    GoalState state;

+    /* Content address for recomputing store path */
+    std::optional<ContentAddress> ca;
+
 public:
-    SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair = NoRepair);
+    SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair = NoRepair, std::optional<ContentAddress> ca = std::nullopt);
    ~SubstitutionGoal();

    void timedOut(Error && ex) override { abort(); };
@ -4340,10 +4347,11 @@ public:
 };


-SubstitutionGoal::SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair)
+SubstitutionGoal::SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair, std::optional<ContentAddress> ca)
    : Goal(worker)
    , storePath(storePath)
    , repair(repair)
+    , ca(ca)
 {
    state = &SubstitutionGoal::init;
    name = fmt("substitution of '%s'", worker.store.printStorePath(this->storePath));
@ -4418,14 +4426,18 @@ void SubstitutionGoal::tryNext()
    sub = subs.front();
    subs.pop_front();

-    if (sub->storeDir != worker.store.storeDir) {
+    if (ca) {
+        subPath = sub->makeFixedOutputPathFromCA(storePath.name(), *ca);
+        if (sub->storeDir == worker.store.storeDir)
+            assert(subPath == storePath);
+    } else if (sub->storeDir != worker.store.storeDir) {
        tryNext();
        return;
    }

    try {
        // FIXME: make async
-        info = sub->queryPathInfo(storePath);
+        info = sub->queryPathInfo(subPath ? *subPath : storePath);
    } catch (InvalidPath &) {
        tryNext();
        return;
@ -4444,6 +4456,19 @@ void SubstitutionGoal::tryNext()
        throw;
    }

+    if (info->path != storePath) {
+        if (info->isContentAddressed(*sub) && info->references.empty()) {
+            auto info2 = std::make_shared<ValidPathInfo>(*info);
+            info2->path = storePath;
+            info = info2;
+        } else {
+            printError("asked '%s' for '%s' but got '%s'",
+                sub->getUri(), worker.store.printStorePath(storePath), sub->printStorePath(info->path));
+            tryNext();
+            return;
+        }
+    }
+
    /* Update the total expected download size. */
    auto narInfo = std::dynamic_pointer_cast<const NarInfo>(info);

@ -4533,7 +4558,7 @@ void SubstitutionGoal::tryToRun()
            PushActivity pact(act.id);

            copyStorePath(ref<Store>(sub), ref<Store>(worker.store.shared_from_this()),
-                storePath, repair, sub->isTrusted ? NoCheckSigs : CheckSigs);
+                subPath ? *subPath : storePath, repair, sub->isTrusted ? NoCheckSigs : CheckSigs);

            promise.set_value();
        } catch (...) {
@ -4666,11 +4691,11 @@ std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(const StorePath
 }


-GoalPtr Worker::makeSubstitutionGoal(const StorePath & path, RepairFlag repair)
+GoalPtr Worker::makeSubstitutionGoal(const StorePath & path, RepairFlag repair, std::optional<ContentAddress> ca)
 {
    GoalPtr goal = substitutionGoals[path].lock(); // FIXME
    if (!goal) {
-        goal = std::make_shared<SubstitutionGoal>(path, *this, repair);
+        goal = std::make_shared<SubstitutionGoal>(path, *this, repair, ca);
        substitutionGoals.insert_or_assign(path, goal);
        wakeUp(goal);
    }
@ -5038,7 +5063,7 @@ void Worker::markContentsGood(const StorePath & path)
 static void primeCache(Store & store, const std::vector<StorePathWithOutputs> & paths)
 {
    StorePathSet willBuild, willSubstitute, unknown;
-    unsigned long long downloadSize, narSize;
+    uint64_t downloadSize, narSize;
    store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);

    if (!willBuild.empty() && 0 == settings.maxBuildJobs && getMachines().empty())
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@ -58,26 +58,6 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
        }
    };

-    /* We always have one output, and if it's a fixed-output derivation (as
-       checked below) it must be the only output */
-    auto & output = drv.outputs.begin()->second;
-
-    /* Try the hashed mirrors first. */
-    if (auto hash = std::get_if<DerivationOutputFixed>(&output.output)) {
-        if (hash->hash.method == FileIngestionMethod::Flat) {
-            for (auto hashedMirror : settings.hashedMirrors.get()) {
-                try {
-                    if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
-                    fetch(hashedMirror + printHashType(hash->hash.hash.type) + "/" + hash->hash.hash.to_string(Base16, false));
-                    return;
-                } catch (Error & e) {
-                    debug(e.what());
-                }
-            }
-        }
-    }
-
-    /* Otherwise try the specified URL. */
    fetch(mainUrl);
 }

--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@ -579,7 +579,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
        auto path = store->parseStorePath(readString(from));
        logger->startWork();
        SubstitutablePathInfos infos;
-        store->querySubstitutablePathInfos({path}, infos);
+        store->querySubstitutablePathInfos({{path, std::nullopt}}, infos);
        logger->stopWork();
        auto i = infos.find(path);
        if (i == infos.end())
@ -595,10 +595,16 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
    }

    case wopQuerySubstitutablePathInfos: {
-        auto paths = readStorePaths<StorePathSet>(*store, from);
-        logger->startWork();
        SubstitutablePathInfos infos;
-        store->querySubstitutablePathInfos(paths, infos);
+        StorePathCAMap pathsMap = {};
+        if (GET_PROTOCOL_MINOR(clientVersion) < 22) {
+            auto paths = readStorePaths<StorePathSet>(*store, from);
+            for (auto & path : paths)
+                pathsMap.emplace(path, std::nullopt);
+        } else
+            pathsMap = readStorePathCAMap(*store, from);
+        logger->startWork();
+        store->querySubstitutablePathInfos(pathsMap, infos);
        logger->stopWork();
        to << infos.size();
        for (auto & i : infos) {
@ -790,7 +796,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
            targets.push_back(store->parsePathWithOutputs(s));
        logger->startWork();
        StorePathSet willBuild, willSubstitute, unknown;
-        unsigned long long downloadSize, narSize;
+        uint64_t downloadSize, narSize;
        store->queryMissing(targets, willBuild, willSubstitute, unknown, downloadSize, narSize);
        logger->stopWork();
        writeStorePaths(*store, to, willBuild);
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@ -500,7 +500,7 @@ struct LocalStore::GCState
    StorePathSet alive;
    bool gcKeepOutputs;
    bool gcKeepDerivations;
-    unsigned long long bytesInvalidated;
+    uint64_t bytesInvalidated;
    bool moveToTrash = true;
    bool shouldDelete;
    GCState(const GCOptions & options, GCResults & results)
@ -518,7 +518,7 @@ bool LocalStore::isActiveTempFile(const GCState & state,

 void LocalStore::deleteGarbage(GCState & state, const Path & path)
 {
-    unsigned long long bytesFreed;
+    uint64_t bytesFreed;
    deletePath(path, bytesFreed);
    state.results.bytesFreed += bytesFreed;
 }
@ -528,7 +528,7 @@ void LocalStore::deletePathRecursive(GCState & state, const Path & path)
 {
    checkInterrupt();

-    unsigned long long size = 0;
+    uint64_t size = 0;

    auto storePath = maybeParseStorePath(path);
    if (storePath && isValidPath(*storePath)) {
@ -687,7 +687,7 @@ void LocalStore::removeUnusedLinks(const GCState & state)
    AutoCloseDir dir(opendir(linksDir.c_str()));
    if (!dir) throw SysError("opening directory '%1%'", linksDir);

-    long long actualSize = 0, unsharedSize = 0;
+    int64_t actualSize = 0, unsharedSize = 0;

    struct dirent * dirent;
    while (errno = 0, dirent = readdir(dir.get())) {
@ -717,10 +717,10 @@ void LocalStore::removeUnusedLinks(const GCState & state)
    struct stat st;
    if (stat(linksDir.c_str(), &st) == -1)
        throw SysError("statting '%1%'", linksDir);
-    long long overhead = st.st_blocks * 512ULL;
+    auto overhead = st.st_blocks * 512ULL;

-    printInfo(format("note: currently hard linking saves %.2f MiB")
-        % ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
+    printInfo("note: currently hard linking saves %.2f MiB",
+        ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
 }


--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@ -335,9 +335,6 @@ public:
        "setuid/setgid bits or with file capabilities."};
 #endif

-    Setting<Strings> hashedMirrors{this, {"http://tarballs.nixos.org/"}, "hashed-mirrors",
-        "A list of servers used by builtins.fetchurl to fetch files by hash."};
-
    Setting<uint64_t> minFree{this, 0, "min-free",
        "Automatically run the garbage collector when free disk space drops below the specified amount."};

--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@ -839,20 +839,32 @@ StorePathSet LocalStore::querySubstitutablePaths(const StorePathSet & paths)
 }


-void LocalStore::querySubstitutablePathInfos(const StorePathSet & paths,
-    SubstitutablePathInfos & infos)
+void LocalStore::querySubstitutablePathInfos(const StorePathCAMap & paths, SubstitutablePathInfos & infos)
 {
    if (!settings.useSubstitutes) return;
    for (auto & sub : getDefaultSubstituters()) {
-        if (sub->storeDir != storeDir) continue;
        for (auto & path : paths) {
-            if (infos.count(path)) continue;
-            debug("checking substituter '%s' for path '%s'", sub->getUri(), printStorePath(path));
+            auto subPath(path.first);
+
+            // recompute store path so that we can use a different store root
+            if (path.second) {
+                subPath = makeFixedOutputPathFromCA(path.first.name(), *path.second);
+                if (sub->storeDir == storeDir)
+                    assert(subPath == path.first);
+                if (subPath != path.first)
+                    debug("replaced path '%s' with '%s' for substituter '%s'", printStorePath(path.first), sub->printStorePath(subPath), sub->getUri());
+            } else if (sub->storeDir != storeDir) continue;
+
+            debug("checking substituter '%s' for path '%s'", sub->getUri(), sub->printStorePath(subPath));
            try {
-                auto info = sub->queryPathInfo(path);
+                auto info = sub->queryPathInfo(subPath);
+
+                if (sub->storeDir != storeDir && !(info->isContentAddressed(*sub) && info->references.empty()))
+                    continue;
+
                auto narInfo = std::dynamic_pointer_cast<const NarInfo>(
                    std::shared_ptr<const ValidPathInfo>(info));
-                infos.insert_or_assign(path, SubstitutablePathInfo{
+                infos.insert_or_assign(path.first, SubstitutablePathInfo{
                    info->deriver,
                    info->references,
                    narInfo ? narInfo->fileSize : 0,
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@ -29,8 +29,8 @@ struct Derivation;
 struct OptimiseStats
 {
    unsigned long filesLinked = 0;
-    unsigned long long bytesFreed = 0;
-    unsigned long long blocksFreed = 0;
+    uint64_t bytesFreed = 0;
+    uint64_t blocksFreed = 0;
 };


@ -139,7 +139,7 @@ public:

    StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

-    void querySubstitutablePathInfos(const StorePathSet & paths,
+    void querySubstitutablePathInfos(const StorePathCAMap & paths,
        SubstitutablePathInfos & infos) override;

    void addToStore(const ValidPathInfo & info, Source & source,
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@ -108,9 +108,19 @@ void Store::computeFSClosure(const StorePath & startPath,
 }


+std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv)
+{
+    auto out = drv.outputs.find("out");
+    if (out != drv.outputs.end()) {
+        if (auto v = std::get_if<DerivationOutputFixed>(&out->second.output))
+            return v->hash;
+    }
+    return std::nullopt;
+}
+
 void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
    StorePathSet & willBuild_, StorePathSet & willSubstitute_, StorePathSet & unknown_,
-    unsigned long long & downloadSize_, unsigned long long & narSize_)
+    uint64_t & downloadSize_, uint64_t & narSize_)
 {
    Activity act(*logger, lvlDebug, actUnknown, "querying info about missing paths");

@ -122,8 +132,8 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
    {
        std::unordered_set<std::string> done;
        StorePathSet & unknown, & willSubstitute, & willBuild;
-        unsigned long long & downloadSize;
-        unsigned long long & narSize;
+        uint64_t & downloadSize;
+        uint64_t & narSize;
    };

    struct DrvState
@ -157,7 +167,7 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
        auto outPath = parseStorePath(outPathS);

        SubstitutablePathInfos infos;
-        querySubstitutablePathInfos({outPath}, infos);
+        querySubstitutablePathInfos({{outPath, getDerivationCA(*drv)}}, infos);

        if (infos.empty()) {
            drvState_->lock()->done = true;
@ -214,7 +224,7 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
            if (isValidPath(path.path)) return;

            SubstitutablePathInfos infos;
-            querySubstitutablePathInfos({path.path}, infos);
+            querySubstitutablePathInfos({{path.path, std::nullopt}}, infos);

            if (infos.empty()) {
                auto state(state_.lock());
--- a/src/libstore/nar-accessor.cc
+++ b/src/libstore/nar-accessor.cc
@ -80,14 +80,14 @@ struct NarAccessor : public FSAccessor
            parents.top()->isExecutable = true;
        }

-        void preallocateContents(unsigned long long size) override
+        void preallocateContents(uint64_t size) override
        {
            assert(size <= std::numeric_limits<uint64_t>::max());
            parents.top()->size = (uint64_t) size;
            parents.top()->start = pos;
        }

-        void receiveContents(unsigned char * data, unsigned int len) override
+        void receiveContents(unsigned char * data, size_t len) override
        { }

        void createSymlink(const Path & path, const string & target) override
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@ -282,7 +282,7 @@ void LocalStore::optimiseStore(OptimiseStats & stats)
    }
 }

-static string showBytes(unsigned long long bytes)
+static string showBytes(uint64_t bytes)
 {
    return (format("%.2f MiB") % (bytes / (1024.0 * 1024.0))).str();
 }
--- a/src/libstore/path.hh
+++ b/src/libstore/path.hh
@ -64,6 +64,8 @@ typedef std::set<StorePath> StorePathSet;
 typedef std::vector<StorePath> StorePaths;
 typedef std::map<string, StorePath> OutputPathMap;

+typedef std::map<StorePath, std::optional<ContentAddress>> StorePathCAMap;
+
 /* Extension of derivations in the Nix store. */
 const std::string drvExtension = ".drv";

--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@ -39,6 +39,24 @@ void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths
        out << store.printStorePath(i);
 }

+StorePathCAMap readStorePathCAMap(const Store & store, Source & from)
+{
+    StorePathCAMap paths;
+    auto count = readNum<size_t>(from);
+    while (count--)
+        paths.insert_or_assign(store.parseStorePath(readString(from)), parseContentAddressOpt(readString(from)));
+    return paths;
+}
+
+void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap & paths)
+{
+    out << paths.size();
+    for (auto & i : paths) {
+        out << store.printStorePath(i.first);
+        out << renderContentAddress(i.second);
+    }
+}
+
 std::map<string, StorePath> readOutputPathMap(const Store & store, Source & from)
 {
    std::map<string, StorePath> pathMap;
@ -332,18 +350,17 @@ StorePathSet RemoteStore::querySubstitutablePaths(const StorePathSet & paths)
 }


-void RemoteStore::querySubstitutablePathInfos(const StorePathSet & paths,
-    SubstitutablePathInfos & infos)
+void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, SubstitutablePathInfos & infos)
 {
-    if (paths.empty()) return;
+    if (pathsMap.empty()) return;

    auto conn(getConnection());

    if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 12) {

-        for (auto & i : paths) {
+        for (auto & i : pathsMap) {
            SubstitutablePathInfo info;
-            conn->to << wopQuerySubstitutablePathInfo << printStorePath(i);
+            conn->to << wopQuerySubstitutablePathInfo << printStorePath(i.first);
            conn.processStderr();
            unsigned int reply = readInt(conn->from);
            if (reply == 0) continue;
@ -353,13 +370,19 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathSet & paths,
            info.references = readStorePaths<StorePathSet>(*this, conn->from);
            info.downloadSize = readLongLong(conn->from);
            info.narSize = readLongLong(conn->from);
-            infos.insert_or_assign(i, std::move(info));
+            infos.insert_or_assign(i.first, std::move(info));
        }

    } else {

        conn->to << wopQuerySubstitutablePathInfos;
-        writeStorePaths(*this, conn->to, paths);
+        if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 22) {
+            StorePathSet paths;
+            for (auto & path : pathsMap)
+                paths.insert(path.first);
+            writeStorePaths(*this, conn->to, paths);
+        } else
+            writeStorePathCAMap(*this, conn->to, pathsMap);
        conn.processStderr();
        size_t count = readNum<size_t>(conn->from);
        for (size_t n = 0; n < count; n++) {
@ -782,7 +805,7 @@ void RemoteStore::addSignatures(const StorePath & storePath, const StringSet & s

 void RemoteStore::queryMissing(const std::vector<StorePathWithOutputs> & targets,
    StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
-    unsigned long long & downloadSize, unsigned long long & narSize)
+    uint64_t & downloadSize, uint64_t & narSize)
 {
    {
        auto conn(getConnection());
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@ -56,7 +56,7 @@ public:

    StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

-    void querySubstitutablePathInfos(const StorePathSet & paths,
+    void querySubstitutablePathInfos(const StorePathCAMap & paths,
        SubstitutablePathInfos & infos) override;

    void addToStore(const ValidPathInfo & info, Source & nar,
@ -94,7 +94,7 @@ public:

    void queryMissing(const std::vector<StorePathWithOutputs> & targets,
        StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
-        unsigned long long & downloadSize, unsigned long long & narSize) override;
+        uint64_t & downloadSize, uint64_t & narSize) override;

    void connect() override;

--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@ -193,6 +193,23 @@ StorePath Store::makeFixedOutputPath(
    }
 }

+// FIXME Put this somewhere?
+template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
+
+StorePath Store::makeFixedOutputPathFromCA(std::string_view name, ContentAddress ca,
+    const StorePathSet & references, bool hasSelfReference) const
+{
+    // New template
+    return std::visit(overloaded {
+        [&](TextHash th) {
+            return makeTextPath(name, th.hash, references);
+        },
+        [&](FixedOutputHash fsh) {
+            return makeFixedOutputPath(fsh.method, fsh.hash, name, references, hasSelfReference);
+        }
+    }, ca);
+}

 StorePath Store::makeTextPath(std::string_view name, const Hash & hash,
    const StorePathSet & references) const
@ -689,6 +706,15 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,

    uint64_t total = 0;

+    // recompute store path on the chance dstStore does it differently
+    if (info->ca && info->references.empty()) {
+        auto info2 = make_ref<ValidPathInfo>(*info);
+        info2->path = dstStore->makeFixedOutputPathFromCA(info->path.name(), *info->ca);
+        if (dstStore->storeDir == srcStore->storeDir)
+            assert(info->path == info2->path);
+        info = info2;
+    }
+
    if (!info->narHash) {
        StringSink sink;
        srcStore->narFromPath({storePath}, sink);
@ -724,7 +750,7 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
 }


-void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & storePaths,
+std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & storePaths,
    RepairFlag repair, CheckSigsFlag checkSigs, SubstituteFlag substitute)
 {
    auto valid = dstStore->queryValidPaths(storePaths, substitute);
@ -733,7 +759,11 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
    for (auto & path : storePaths)
        if (!valid.count(path)) missing.insert(path);

-    if (missing.empty()) return;
+    std::map<StorePath, StorePath> pathsMap;
+    for (auto & path : storePaths)
+        pathsMap.insert_or_assign(path, path);
+
+    if (missing.empty()) return pathsMap;

    Activity act(*logger, lvlInfo, actCopyPaths, fmt("copying %d paths", missing.size()));

@ -752,14 +782,23 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
        StorePathSet(missing.begin(), missing.end()),

        [&](const StorePath & storePath) {
+            auto info = srcStore->queryPathInfo(storePath);
+            auto storePathForDst = storePath;
+            if (info->ca && info->references.empty()) {
+                storePathForDst = dstStore->makeFixedOutputPathFromCA(storePath.name(), *info->ca);
+                if (dstStore->storeDir == srcStore->storeDir)
+                    assert(storePathForDst == storePath);
+                if (storePathForDst != storePath)
+                    debug("replaced path '%s' to '%s' for substituter '%s'", srcStore->printStorePath(storePath), dstStore->printStorePath(storePathForDst), dstStore->getUri());
+            }
+            pathsMap.insert_or_assign(storePath, storePathForDst);
+
            if (dstStore->isValidPath(storePath)) {
                nrDone++;
                showProgress();
                return StorePathSet();
            }

-            auto info = srcStore->queryPathInfo(storePath);
-
            bytesExpected += info->narSize;
            act.setExpected(actCopyPath, bytesExpected);

@ -769,7 +808,19 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
        [&](const StorePath & storePath) {
            checkInterrupt();

-            if (!dstStore->isValidPath(storePath)) {
+            auto info = srcStore->queryPathInfo(storePath);
+
+            auto storePathForDst = storePath;
+            if (info->ca && info->references.empty()) {
+                storePathForDst = dstStore->makeFixedOutputPathFromCA(storePath.name(), *info->ca);
+                if (dstStore->storeDir == srcStore->storeDir)
+                    assert(storePathForDst == storePath);
+                if (storePathForDst != storePath)
+                    debug("replaced path '%s' to '%s' for substituter '%s'", srcStore->printStorePath(storePath), dstStore->printStorePath(storePathForDst), dstStore->getUri());
+            }
+            pathsMap.insert_or_assign(storePath, storePathForDst);
+
+            if (!dstStore->isValidPath(storePathForDst)) {
                MaintainCount<decltype(nrRunning)> mc(nrRunning);
                showProgress();
                try {
@ -787,6 +838,8 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
            nrDone++;
            showProgress();
        });
+
+    return pathsMap;
 }


@ -863,10 +916,6 @@ void ValidPathInfo::sign(const Store & store, const SecretKey & secretKey)
    sigs.insert(secretKey.signDetached(fingerprint(store)));
 }

-// FIXME Put this somewhere?
-template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
-template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
-
 bool ValidPathInfo::isContentAddressed(const Store & store) const
 {
    if (! ca) return false;
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@ -85,7 +85,7 @@ struct GCOptions
    StorePathSet pathsToDelete;

    /* Stop after at least `maxFreed' bytes have been freed. */
-    unsigned long long maxFreed{std::numeric_limits<unsigned long long>::max()};
+    uint64_t maxFreed{std::numeric_limits<uint64_t>::max()};
 };


@ -97,7 +97,7 @@ struct GCResults

    /* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
       number of bytes that would be or was freed. */
-    unsigned long long bytesFreed = 0;
+    uint64_t bytesFreed = 0;
 };


@ -105,8 +105,8 @@ struct SubstitutablePathInfo
 {
    std::optional<StorePath> deriver;
    StorePathSet references;
-    unsigned long long downloadSize; /* 0 = unknown or inapplicable */
-    unsigned long long narSize; /* 0 = unknown */
+    uint64_t downloadSize; /* 0 = unknown or inapplicable */
+    uint64_t narSize; /* 0 = unknown */
 };

 typedef std::map<StorePath, SubstitutablePathInfo> SubstitutablePathInfos;
@ -344,7 +344,11 @@ public:
        bool hasSelfReference = false) const;

    StorePath makeTextPath(std::string_view name, const Hash & hash,
-        const StorePathSet & references) const;
+        const StorePathSet & references = {}) const;
+
+    StorePath makeFixedOutputPathFromCA(std::string_view name, ContentAddress ca,
+        const StorePathSet & references = {},
+        bool hasSelfReference = false) const;

    /* This is the preparatory part of addToStore(); it computes the
       store path to which srcPath is to be copied.  Returns the store
@ -436,9 +440,10 @@ public:
    virtual StorePathSet querySubstitutablePaths(const StorePathSet & paths) { return {}; };

    /* Query substitute info (i.e. references, derivers and download
-       sizes) of a set of paths.  If a path does not have substitute
-       info, it's omitted from the resulting ‘infos’ map. */
-    virtual void querySubstitutablePathInfos(const StorePathSet & paths,
+       sizes) of a map of paths to their optional ca values. If a path
+       does not have substitute info, it's omitted from the resulting
+       ‘infos’ map. */
+    virtual void querySubstitutablePathInfos(const StorePathCAMap & paths,
        SubstitutablePathInfos & infos) { return; };

    /* Import a path into the store. */
@ -610,7 +615,7 @@ public:
       that will be substituted. */
    virtual void queryMissing(const std::vector<StorePathWithOutputs> & targets,
        StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
-        unsigned long long & downloadSize, unsigned long long & narSize);
+        uint64_t & downloadSize, uint64_t & narSize);

    /* Sort a set of paths topologically under the references
       relation.  If p refers to q, then p precedes q in this list. */
@ -740,11 +745,13 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,


 /* 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 StorePathSet & storePaths,
+   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. Returns a map of what each path was copied to the dstStore
+   as. */
+std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStore,
+    const StorePathSet & storePaths,
    RepairFlag repair = NoRepair,
    CheckSigsFlag checkSigs = CheckSigs,
    SubstituteFlag substitute = NoSubstitute);
@ -843,4 +850,6 @@ std::optional<ValidPathInfo> decodeValidPathInfo(
 /* Split URI into protocol+hierarchy part and its parameter set. */
 std::pair<std::string, Store::Params> splitUriAndParams(const std::string & uri);

+std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv);
+
 }
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@ -70,6 +70,10 @@ template<class T> T readStorePaths(const Store & store, Source & from);

 void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths);

+StorePathCAMap readStorePathCAMap(const Store & store, Source & from);
+
+void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap & paths);
+
 void writeOutputPathMap(const Store & store, Sink & out, const OutputPathMap & paths);

 }
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@ -150,17 +150,17 @@ static void skipGeneric(Source & source)

 static void parseContents(ParseSink & sink, Source & source, const Path & path)
 {
-    unsigned long long size = readLongLong(source);
+    uint64_t size = readLongLong(source);

    sink.preallocateContents(size);

-    unsigned long long left = size;
+    uint64_t left = size;
    std::vector<unsigned char> buf(65536);

    while (left) {
        checkInterrupt();
        auto n = buf.size();
-        if ((unsigned long long)n > left) n = left;
+        if ((uint64_t)n > left) n = left;
        source(buf.data(), n);
        sink.receiveContents(buf.data(), n);
        left -= n;
@ -323,7 +323,7 @@ struct RestoreSink : ParseSink
            throw SysError("fchmod");
    }

-    void preallocateContents(unsigned long long len)
+    void preallocateContents(uint64_t len)
    {
 #if HAVE_POSIX_FALLOCATE
        if (len) {
@ -338,7 +338,7 @@ struct RestoreSink : ParseSink
 #endif
    }

-    void receiveContents(unsigned char * data, unsigned int len)
+    void receiveContents(unsigned char * data, size_t len)
    {
        writeFull(fd.get(), data, len);
    }
--- a/src/libutil/archive.hh
+++ b/src/libutil/archive.hh
@ -57,8 +57,8 @@ struct ParseSink

    virtual void createRegularFile(const Path & path) { };
    virtual void isExecutable() { };
-    virtual void preallocateContents(unsigned long long size) { };
-    virtual void receiveContents(unsigned char * data, unsigned int len) { };
+    virtual void preallocateContents(uint64_t size) { };
+    virtual void receiveContents(unsigned char * data, size_t len) { };

    virtual void createSymlink(const Path & path, const string & target) { };
 };
@ -77,7 +77,7 @@ struct RetrieveRegularNARSink : ParseSink
        regular = false;
    }

-    void receiveContents(unsigned char * data, unsigned int len)
+    void receiveContents(unsigned char * data, size_t len)
    {
        sink(data, len);
    }
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@ -111,7 +111,7 @@ Hash hashFile(HashType ht, const Path & path);

 /* Compute the hash of the given path.  The hash is defined as
   (essentially) hashString(ht, dumpPath(path)). */
-typedef std::pair<Hash, unsigned long long> HashResult;
+typedef std::pair<Hash, uint64_t> HashResult;
 HashResult hashPath(HashType ht, const Path & path,
    PathFilter & filter = defaultPathFilter);

@ -141,7 +141,7 @@ class HashSink : public BufferedSink, public AbstractHashSink
 private:
    HashType ht;
    Ctx * ctx;
-    unsigned long long bytes;
+    uint64_t bytes;

 public:
    HashSink(HashType ht);
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@ -312,14 +312,14 @@ T readNum(Source & source)
    source(buf, sizeof(buf));

    uint64_t n =
-        ((unsigned long long) buf[0]) |
-        ((unsigned long long) buf[1] << 8) |
-        ((unsigned long long) buf[2] << 16) |
-        ((unsigned long long) buf[3] << 24) |
-        ((unsigned long long) buf[4] << 32) |
-        ((unsigned long long) buf[5] << 40) |
-        ((unsigned long long) buf[6] << 48) |
-        ((unsigned long long) buf[7] << 56);
+        ((uint64_t) buf[0]) |
+        ((uint64_t) buf[1] << 8) |
+        ((uint64_t) buf[2] << 16) |
+        ((uint64_t) buf[3] << 24) |
+        ((uint64_t) buf[4] << 32) |
+        ((uint64_t) buf[5] << 40) |
+        ((uint64_t) buf[6] << 48) |
+        ((uint64_t) buf[7] << 56);

    if (n > std::numeric_limits<T>::max())
        throw SerialisationError("serialised integer %d is too large for type '%s'", n, typeid(T).name());
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@ -374,7 +374,7 @@ void writeLine(int fd, string s)
 }


-static void _deletePath(int parentfd, const Path & path, unsigned long long & bytesFreed)
+static void _deletePath(int parentfd, const Path & path, uint64_t & bytesFreed)
 {
    checkInterrupt();

@ -414,7 +414,7 @@ static void _deletePath(int parentfd, const Path & path, unsigned long long & by
    }
 }

-static void _deletePath(const Path & path, unsigned long long & bytesFreed)
+static void _deletePath(const Path & path, uint64_t & bytesFreed)
 {
    Path dir = dirOf(path);
    if (dir == "")
@ -435,12 +435,12 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed)

 void deletePath(const Path & path)
 {
-    unsigned long long dummy;
+    uint64_t dummy;
    deletePath(path, dummy);
 }


-void deletePath(const Path & path, unsigned long long & bytesFreed)
+void deletePath(const Path & path, uint64_t & bytesFreed)
 {
    //Activity act(*logger, lvlDebug, format("recursively deleting path '%1%'") % path);
    bytesFreed = 0;
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@ -125,7 +125,7 @@ void writeLine(int fd, string s);
   second variant returns the number of bytes and blocks freed. */
 void deletePath(const Path & path);

-void deletePath(const Path & path, unsigned long long & bytesFreed);
+void deletePath(const Path & path, uint64_t & bytesFreed);

 std::string getUserName();

--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@ -174,7 +174,7 @@ static void _main(int argc, char * * argv)
        else if (*arg == "--run-env") // obsolete
            runEnv = true;

-        else if (*arg == "--command" || *arg == "--run") {
+        else if (runEnv && (*arg == "--command" || *arg == "--run")) {
            if (*arg == "--run")
                interactive = false;
            envCommand = getArg(*arg, arg, end) + "\nexit";
@ -192,7 +192,7 @@ static void _main(int argc, char * * argv)
        else if (*arg == "--pure") pure = true;
        else if (*arg == "--impure") pure = false;

-        else if (*arg == "--packages" || *arg == "-p")
+        else if (runEnv && (*arg == "--packages" || *arg == "-p"))
            packages = true;

        else if (inShebang && *arg == "-i") {
@ -325,7 +325,7 @@ static void _main(int argc, char * * argv)
    auto buildPaths = [&](const std::vector<StorePathWithOutputs> & paths) {
        /* Note: we do this even when !printMissing to efficiently
           fetch binary cache data. */
-        unsigned long long downloadSize, narSize;
+        uint64_t downloadSize, narSize;
        StorePathSet willBuild, willSubstitute, unknown;
        store->queryMissing(paths,
            willBuild, willSubstitute, unknown, downloadSize, narSize);
--- a/src/nix-collect-garbage/nix-collect-garbage.cc
+++ b/src/nix-collect-garbage/nix-collect-garbage.cc
@ -67,10 +67,8 @@ static int _main(int argc, char * * argv)
                deleteOlderThan = getArg(*arg, arg, end);
            }
            else if (*arg == "--dry-run") dryRun = true;
-            else if (*arg == "--max-freed") {
-                long long maxFreed = getIntArg<long long>(*arg, arg, end, true);
-                options.maxFreed = maxFreed >= 0 ? maxFreed : 0;
-            }
+            else if (*arg == "--max-freed")
+                options.maxFreed = std::max(getIntArg<int64_t>(*arg, arg, end, true), (int64_t) 0);
            else
                return false;
            return true;
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@ -130,7 +130,7 @@ static void opRealise(Strings opFlags, Strings opArgs)
    for (auto & i : opArgs)
        paths.push_back(store->followLinksToStorePathWithOutputs(i));

-    unsigned long long downloadSize, narSize;
+    uint64_t downloadSize, narSize;
    StorePathSet willBuild, willSubstitute, unknown;
    store->queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);

@ -572,10 +572,8 @@ static void opGC(Strings opFlags, Strings opArgs)
        if (*i == "--print-roots") printRoots = true;
        else if (*i == "--print-live") options.action = GCOptions::gcReturnLive;
        else if (*i == "--print-dead") options.action = GCOptions::gcReturnDead;
-        else if (*i == "--max-freed") {
-            long long maxFreed = getIntArg<long long>(*i, i, opFlags.end(), true);
-            options.maxFreed = maxFreed >= 0 ? maxFreed : 0;
-        }
+        else if (*i == "--max-freed")
+            options.maxFreed = std::max(getIntArg<int64_t>(*i, i, opFlags.end(), true), (int64_t) 0);
        else throw UsageError("bad sub-operation '%1%' in GC", *i);

    if (!opArgs.empty()) throw UsageError("no arguments expected");
@ -831,7 +829,7 @@ static void opServe(Strings opFlags, Strings opArgs)
                    for (auto & path : paths)
                        if (!path.isDerivation())
                            paths2.push_back({path});
-                    unsigned long long downloadSize, narSize;
+                    uint64_t downloadSize, narSize;
                    StorePathSet willBuild, willSubstitute, unknown;
                    store->queryMissing(paths2,
                        willBuild, willSubstitute, unknown, downloadSize, narSize);
--- a/src/nix/add-to-store.cc
+++ b/src/nix/add-to-store.cc
@ -9,6 +9,7 @@ struct CmdAddToStore : MixDryRun, StoreCommand
 {
    Path path;
    std::optional<std::string> namePart;
+    FileIngestionMethod ingestionMethod = FileIngestionMethod::Recursive;

    CmdAddToStore()
    {
@ -21,6 +22,13 @@ struct CmdAddToStore : MixDryRun, StoreCommand
            .labels = {"name"},
            .handler = {&namePart},
        });
+
+        addFlag({
+            .longName = "flat",
+            .shortName = 0,
+            .description = "add flat file to the Nix store",
+            .handler = {&ingestionMethod, FileIngestionMethod::Flat},
+        });
    }

    std::string description() override
@ -45,12 +53,19 @@ struct CmdAddToStore : MixDryRun, StoreCommand

        auto narHash = hashString(htSHA256, *sink.s);

-        ValidPathInfo info(store->makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, *namePart));
+        Hash hash = narHash;
+        if (ingestionMethod == FileIngestionMethod::Flat) {
+            HashSink hsink(htSHA256);
+            readFile(path, hsink);
+            hash = hsink.finish().first;
+        }
+
+        ValidPathInfo info(store->makeFixedOutputPath(ingestionMethod, hash, *namePart));
        info.narHash = narHash;
        info.narSize = sink.s->size();
        info.ca = std::optional { FixedOutputHash {
-            .method = FileIngestionMethod::Recursive,
-            .hash = *info.narHash,
+            .method = ingestionMethod,
+            .hash = hash,
        } };

        if (!dryRun) {
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@ -0,0 +1,127 @@
+#include "command.hh"
+#include "common-args.hh"
+#include "shared.hh"
+#include "store-api.hh"
+#include "fs-accessor.hh"
+
+using namespace nix;
+
+struct CmdBundle : InstallableCommand
+{
+    std::string bundler = "github:matthewbauer/nix-bundle";
+    std::optional<Path> outLink;
+
+    CmdBundle()
+    {
+        addFlag({
+            .longName = "bundler",
+            .description = "use custom bundler",
+            .labels = {"flake-url"},
+            .handler = {&bundler},
+            .completer = {[&](size_t, std::string_view prefix) {
+                completeFlakeRef(getStore(), prefix);
+            }}
+        });
+
+        addFlag({
+            .longName = "out-link",
+            .shortName = 'o',
+            .description = "path of the symlink to the build result",
+            .labels = {"path"},
+            .handler = {&outLink},
+            .completer = completePath
+        });
+    }
+
+    std::string description() override
+    {
+        return "bundle an application so that it works outside of the Nix store";
+    }
+
+    Examples examples() override
+    {
+        return {
+            Example{
+                "To bundle Hello:",
+                "nix bundle hello"
+            },
+        };
+    }
+
+    Strings getDefaultFlakeAttrPaths() override
+    {
+        Strings res{"defaultApp." + settings.thisSystem.get()};
+        for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
+            res.push_back(s);
+        return res;
+    }
+
+    Strings getDefaultFlakeAttrPathPrefixes() override
+    {
+        Strings res{"apps." + settings.thisSystem.get() + ".", "packages"};
+        for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
+            res.push_back(s);
+        return res;
+    }
+
+    void run(ref<Store> store) override
+    {
+        auto evalState = getEvalState();
+
+        auto app = installable->toApp(*evalState);
+        store->buildPaths(app.context);
+
+        auto [bundlerFlakeRef, bundlerName] = parseFlakeRefWithFragment(bundler, absPath("."));
+        const flake::LockFlags lockFlags{ .writeLockFile = false };
+        auto bundler = InstallableFlake(
+            evalState, std::move(bundlerFlakeRef),
+            Strings{bundlerName == "" ? "defaultBundler" : bundlerName},
+            Strings({"bundlers."}), lockFlags);
+
+        Value * arg = evalState->allocValue();
+        evalState->mkAttrs(*arg, 2);
+
+        PathSet context;
+        for (auto & i : app.context)
+            context.insert("=" + store->printStorePath(i.path));
+        mkString(*evalState->allocAttr(*arg, evalState->symbols.create("program")), app.program, context);
+
+        mkString(*evalState->allocAttr(*arg, evalState->symbols.create("system")), settings.thisSystem.get());
+
+        arg->attrs->sort();
+ 
+        auto vRes = evalState->allocValue();
+        evalState->callFunction(*bundler.toValue(*evalState).first, *arg, *vRes, noPos);
+
+        if (!evalState->isDerivation(*vRes))
+            throw Error("the bundler '%s' does not produce a derivation", bundler.what());
+
+        auto attr1 = vRes->attrs->find(evalState->sDrvPath);
+        if (!attr1)
+            throw Error("the bundler '%s' does not produce a derivation", bundler.what());
+
+        PathSet context2;
+        StorePath drvPath = store->parseStorePath(evalState->coerceToPath(*attr1->pos, *attr1->value, context2));
+
+        auto attr2 = vRes->attrs->find(evalState->sOutPath);
+        if (!attr2)
+            throw Error("the bundler '%s' does not produce a derivation", bundler.what());
+
+        StorePath outPath = store->parseStorePath(evalState->coerceToPath(*attr2->pos, *attr2->value, context2));
+
+        store->buildPaths({{drvPath}});
+
+        auto outPathS = store->printStorePath(outPath);
+
+        auto info = store->queryPathInfo(outPath);
+        if (!info->references.empty())
+            throw Error("'%s' has references; a bundler must not leave any references", outPathS);
+
+        if (!outLink)
+            outLink = baseNameOf(app.program);
+
+        store.dynamic_pointer_cast<LocalFSStore>()->addPermRoot(outPath, absPath(*outLink), true);
+    }
+};
+
+static auto r2 = registerCommand<CmdBundle>("bundle");
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@ -368,6 +368,21 @@ struct CmdFlakeCheck : FlakeCommand
            }
        };

+        auto checkBundler = [&](const std::string & attrPath, Value & v, const Pos & pos) {
+            try {
+                state->forceValue(v, pos);
+                if (v.type != tLambda)
+                    throw Error("bundler must be a function");
+                if (!v.lambda.fun->formals ||
+                    v.lambda.fun->formals->argNames.find(state->symbols.create("program")) == v.lambda.fun->formals->argNames.end() ||
+                    v.lambda.fun->formals->argNames.find(state->symbols.create("system")) == v.lambda.fun->formals->argNames.end())
+                    throw Error("bundler must take formal arguments 'program' and 'system'");
+            } catch (Error & e) {
+                e.addTrace(pos, hintfmt("while checking the template '%s'", attrPath));
+                throw;
+            }
+        };
+
        {
            Activity act(*logger, lvlInfo, actUnknown, "evaluating flake");

@ -490,6 +505,16 @@ struct CmdFlakeCheck : FlakeCommand
                                    *attr.value, *attr.pos);
                        }

+                        else if (name == "defaultBundler")
+                            checkBundler(name, vOutput, pos);
+
+                        else if (name == "bundlers") {
+                            state->forceAttrs(vOutput, pos);
+                            for (auto & attr : *vOutput.attrs)
+                                checkBundler(fmt("%s.%s", name, attr.name),
+                                    *attr.value, *attr.pos);
+                        }
+
                        else
                            warn("unknown flake output '%s'", name);

--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@ -61,7 +61,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
        };
    }

-    void printSize(unsigned long long value)
+    void printSize(uint64_t value)
    {
        if (!humanReadable) {
            std::cout << fmt("\t%11d", value);
--- a/tests/check.sh
+++ b/tests/check.sh
@ -61,30 +61,30 @@ nix-build check.nix -A nondeterministic --no-out-link --repeat 1 2> $TEST_ROOT/l
 [ "$status" = "1" ]
 grep 'differs from previous round' $TEST_ROOT/log

-path=$(nix-build check.nix -A fetchurl --no-out-link --hashed-mirrors '')
+path=$(nix-build check.nix -A fetchurl --no-out-link)

 chmod +w $path
 echo foo > $path
 chmod -w $path

-nix-build check.nix -A fetchurl --no-out-link --check --hashed-mirrors ''
+nix-build check.nix -A fetchurl --no-out-link --check
 # Note: "check" doesn't repair anything, it just compares to the hash stored in the database.
 [[ $(cat $path) = foo ]]

-nix-build check.nix -A fetchurl --no-out-link --repair --hashed-mirrors ''
+nix-build check.nix -A fetchurl --no-out-link --repair
 [[ $(cat $path) != foo ]]

-nix-build check.nix -A hashmismatch --no-out-link --hashed-mirrors '' || status=$?
+nix-build check.nix -A hashmismatch --no-out-link || status=$?
 [ "$status" = "102" ]

 echo -n > ./dummy
-nix-build check.nix -A hashmismatch --no-out-link --hashed-mirrors ''
+nix-build check.nix -A hashmismatch --no-out-link
 echo 'Hello World' > ./dummy

-nix-build check.nix -A hashmismatch --no-out-link --check --hashed-mirrors '' || status=$?
+nix-build check.nix -A hashmismatch --no-out-link --check || status=$?
 [ "$status" = "102" ]

 # Multiple failures with --keep-going
 nix-build check.nix -A nondeterministic --no-out-link
-nix-build check.nix -A nondeterministic -A hashmismatch --no-out-link --check --keep-going --hashed-mirrors '' || status=$?
+nix-build check.nix -A nondeterministic -A hashmismatch --no-out-link --check --keep-going || status=$?
 [ "$status" = "110" ]
--- a/tests/fetchurl.sh
+++ b/tests/fetchurl.sh
@ -5,7 +5,7 @@ clearStore
 # Test fetching a flat file.
 hash=$(nix-hash --flat --type sha256 ./fetchurl.sh)

-outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha256 $hash --no-out-link --hashed-mirrors '')
+outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha256 $hash --no-out-link)

 cmp $outPath fetchurl.sh

@ -14,7 +14,7 @@ clearStore

 hash=$(nix hash-file --type sha512 --base64 ./fetchurl.sh)

-outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha512 $hash --no-out-link --hashed-mirrors '')
+outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr sha512 $hash --no-out-link)

 cmp $outPath fetchurl.sh

@ -25,26 +25,24 @@ hash=$(nix hash-file ./fetchurl.sh)

 [[ $hash =~ ^sha256- ]]

-outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr hash $hash --no-out-link --hashed-mirrors '')
+outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file://$(pwd)/fetchurl.sh --argstr hash $hash --no-out-link)

 cmp $outPath fetchurl.sh

-# Test the hashed mirror feature.
+# Test that we can substitute from a different store dir.
 clearStore

-hash=$(nix hash-file --type sha512 --base64 ./fetchurl.sh)
-hash32=$(nix hash-file --type sha512 --base16 ./fetchurl.sh)
+other_store=file://$TEST_ROOT/other_store?store=/fnord/store

-mirror=$TEST_ROOT/hashed-mirror
-rm -rf $mirror
-mkdir -p $mirror/sha512
-ln -s $(pwd)/fetchurl.sh $mirror/sha512/$hash32
+hash=$(nix hash-file --type sha256 --base16 ./fetchurl.sh)

-outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file:///no-such-dir/fetchurl.sh --argstr sha512 $hash --no-out-link --hashed-mirrors "file://$mirror")
+storePath=$(nix --store $other_store add-to-store --flat ./fetchurl.sh)
+
+outPath=$(nix-build '<nix/fetchurl.nix>' --argstr url file:///no-such-dir/fetchurl.sh --argstr sha256 $hash --no-out-link --substituters $other_store)

 # Test hashed mirrors with an SRI hash.
-nix-build '<nix/fetchurl.nix>' --argstr url file:///no-such-dir/fetchurl.sh --argstr hash $(nix to-sri --type sha512 $hash) \
-          --argstr name bla --no-out-link --hashed-mirrors "file://$mirror"
+nix-build '<nix/fetchurl.nix>' --argstr url file:///no-such-dir/fetchurl.sh --argstr hash $(nix to-sri --type sha256 $hash) \
+          --no-out-link --substituters $other_store

 # Test unpacking a NAR.
 rm -rf $TEST_ROOT/archive
--- a/tests/filter-source.sh
+++ b/tests/filter-source.sh
@ -10,10 +10,16 @@ touch $TEST_ROOT/filterin/bak
 touch $TEST_ROOT/filterin/bla.c.bak
 ln -s xyzzy $TEST_ROOT/filterin/link

-nix-build ./filter-source.nix -o $TEST_ROOT/filterout
+checkFilter() {
+    test ! -e $1/foo/bar
+    test -e $1/xyzzy
+    test -e $1/bak
+    test ! -e $1/bla.c.bak
+    test ! -L $1/link
+}

-test ! -e $TEST_ROOT/filterout/foo/bar
-test -e $TEST_ROOT/filterout/xyzzy
-test -e $TEST_ROOT/filterout/bak
-test ! -e $TEST_ROOT/filterout/bla.c.bak
-test ! -L $TEST_ROOT/filterout/link
+nix-build ./filter-source.nix -o $TEST_ROOT/filterout1
+checkFilter $TEST_ROOT/filterout1
+
+nix-build ./path.nix -o $TEST_ROOT/filterout2
+checkFilter $TEST_ROOT/filterout2
--- a/tests/path.nix
+++ b/tests/path.nix
@ -0,0 +1,14 @@
+with import ./config.nix;
+
+mkDerivation {
+  name = "filter";
+  builder = builtins.toFile "builder" "ln -s $input $out";
+  input =
+    builtins.path {
+      path = ((builtins.getEnv "TEST_ROOT") + "/filterin");
+      filter = path: type:
+           type != "symlink"
+        && baseNameOf path != "foo"
+        && !((import ./lang/lib.nix).hasSuffix ".bak" (baseNameOf path));
+    };
+}