Merge branch 'master' into access-tokens

.github/workflows/test.yml

@@ -12,8 +12,6 @@ jobs:
     - uses: actions/checkout@v2
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v10
+    - uses: cachix/install-nix-action@v11
-      with:
-        skip_adding_nixpkgs_channel: true
     #- run: nix flake check
     - run: nix-build -A checks.$(if [[ `uname` = Linux ]]; then echo x86_64-linux; else echo x86_64-darwin; fi)

.gitignore

@@ -12,15 +12,6 @@ perl/Makefile.config
 /svn-revision
 /libtool
 
-/corepkgs/config.nix
-
-# /corepkgs/channels/
-/corepkgs/channels/unpack.sh
-
-# /corepkgs/nar/
-/corepkgs/nar/nar.sh
-/corepkgs/nar/unnar.sh
-
 # /doc/manual/
 /doc/manual/*.1
 /doc/manual/*.5

Makefile

@@ -26,7 +26,7 @@ OPTIMIZE = 1
 ifeq ($(OPTIMIZE), 1)
   GLOBAL_CXXFLAGS += -O3
 else
-  GLOBAL_CXXFLAGS += -O0
+  GLOBAL_CXXFLAGS += -O0 -U_FORTIFY_SOURCE
 endif
 
 include mk/lib.mk

README.md

@@ -9,7 +9,7 @@ for more details.
 
 ## Installation
 
-On Linux and macOS the easiest way to Install Nix is to run the following shell command
+On Linux and macOS the easiest way to install Nix is to run the following shell command
 (as a user other than root):
 
 ```console

corepkgs/config.nix.in

@@ -1,13 +0,0 @@
-# FIXME: remove this file?
-let
-  fromEnv = var: def:
-    let val = builtins.getEnv var; in
-    if val != "" then val else def;
-in rec {
-  nixBinDir = fromEnv "NIX_BIN_DIR" "@bindir@";
-  nixPrefix = "@prefix@";
-  nixLibexecDir = fromEnv "NIX_LIBEXEC_DIR" "@libexecdir@";
-  nixLocalstateDir = "@localstatedir@";
-  nixSysconfDir = "@sysconfdir@";
-  nixStoreDir = fromEnv "NIX_STORE_DIR" "@storedir@";
-}

corepkgs/local.mk

@@ -1,8 +1,4 @@
 corepkgs_FILES = \
-  unpack-channel.nix \
-  derivation.nix \
   fetchurl.nix
 
-$(foreach file,config.nix $(corepkgs_FILES),$(eval $(call install-data-in,$(d)/$(file),$(datadir)/nix/corepkgs)))
+$(foreach file,$(corepkgs_FILES),$(eval $(call install-data-in,$(d)/$(file),$(datadir)/nix/corepkgs)))
-
-template-files += $(d)/config.nix

doc/manual/src/command-ref/nix-prefetch-url.md

@@ -51,6 +51,9 @@ Nix store is also printed.
     result to the Nix store. The resulting hash can be used with
     functions such as Nixpkgs’s `fetchzip` or `fetchFromGitHub`.
 
+  - `--executable`  
+    Set the executable bit on the downloaded file.
+
   - `--name` *name*  
     Override the name of the file in the Nix store. By default, this is
     `hash-basename`, where *basename* is the last component of *url*.

doc/manual/src/hacking.md

@@ -39,17 +39,17 @@ To build Nix itself in this shell:
 
 ```console
 [nix-shell]$ ./bootstrap.sh
-[nix-shell]$ ./configure $configureFlags --prefix=$(pwd)/inst
+[nix-shell]$ ./configure $configureFlags --prefix=$(pwd)/outputs/out
 [nix-shell]$ make -j $NIX_BUILD_CORES
 ```
 
-To install it in `$(pwd)/inst` and test it:
+To install it in `$(pwd)/outputs` and test it:
 
 ```console
 [nix-shell]$ make install
-[nix-shell]$ make installcheck
+[nix-shell]$ make installcheck -j $NIX_BUILD_CORES
-[nix-shell]$ ./inst/bin/nix --version
+[nix-shell]$ ./outputs/out/bin/nix --version
-nix (Nix) 2.4
+nix (Nix) 3.0
 ```
 
 To run a functional test:
@@ -58,6 +58,12 @@ To run a functional test:
 make tests/test-name-should-auto-complete.sh.test
 ```
 
+To run the unit-tests for C++ code:
+
+```
+make check
+```
+
 If you have a flakes-enabled Nix you can replace:
 
 ```console

flake.lock

@@ -3,16 +3,15 @@
     "lowdown-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1598296217,
+        "lastModified": 1598695561,
-        "narHash": "sha256-ha7lyNY1d8m+osmDpPc9f/bfZ3ZC1IVIXwfyklSWg8I=",
+        "narHash": "sha256-gyH/5j+h/nWw0W8AcR2WKvNBUsiQ7QuxqSJNXAwV+8E=",
-        "owner": "edolstra",
+        "owner": "kristapsdz",
         "repo": "lowdown",
-        "rev": "c7a4e715af1e233080842db82d15b261cb74cb28",
+        "rev": "1705b4a26fbf065d9574dce47a94e8c7c79e052f",
         "type": "github"
       },
       "original": {
-        "owner": "edolstra",
+        "owner": "kristapsdz",
-        "ref": "no-structs-in-anonymous-unions",
         "repo": "lowdown",
         "type": "github"
       }

flake.nix

@@ -2,7 +2,7 @@
   description = "The purely functional package manager";
 
   inputs.nixpkgs.url = "nixpkgs/nixos-20.03-small";
-  inputs.lowdown-src = { url = "github:edolstra/lowdown/no-structs-in-anonymous-unions"; flake = false; };
+  inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
   outputs = { self, nixpkgs, lowdown-src }:
 
@@ -58,6 +58,7 @@
         configureFlags =
           lib.optionals stdenv.isLinux [
             "--with-sandbox-shell=${sh}/bin/busybox"
+            "LDFLAGS=-fuse-ld=gold"
           ];
 
         buildDeps =
@@ -136,7 +137,7 @@
 
           enableParallelBuilding = true;
 
-          makeFlags = "profiledir=$(out)/etc/profile.d";
+          makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
 
           doCheck = true;
 
@@ -334,9 +335,6 @@
             # syntax-check generated dot files, it still requires some
             # fonts.  So provide those.
             FONTCONFIG_FILE = texFunctions.fontsConf;
-
-            # To test building without precompiled headers.
-            makeFlagsArray = [ "PRECOMPILE_HEADERS=0" ];
           };
 
         # System tests.

misc/launchd/org.nixos.nix-daemon.plist.in

@@ -4,6 +4,8 @@
   <dict>
     <key>EnvironmentVariables</key>
     <dict>
+      <key>NIX_SSL_CERT_FILE</key>
+      <string>/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt</string>
       <key>OBJC_DISABLE_INITIALIZE_FORK_SAFETY</key>
       <string>YES</string>
     </dict>

mk/precompiled-headers.mk

@@ -1,4 +1,4 @@
-PRECOMPILE_HEADERS ?= 1
+PRECOMPILE_HEADERS ?= 0
 
 print-var-help += \
   echo "  PRECOMPILE_HEADERS ($(PRECOMPILE_HEADERS)): Whether to use precompiled headers to speed up the build";

perl/configure.ac

@@ -70,19 +70,6 @@ PKG_CHECK_MODULES([NIX], [nix-store])
 
 NEED_PROG([NIX], [nix])
 
-# Get nix configure values
-export NIX_REMOTE=daemon
-nixbindir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixBinDir)
-nixlibexecdir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixLibexecDir)
-nixlocalstatedir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixLocalstateDir)
-nixsysconfdir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixSysconfDir)
-nixstoredir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixStoreDir)
-AC_SUBST(nixbindir)
-AC_SUBST(nixlibexecdir)
-AC_SUBST(nixlocalstatedir)
-AC_SUBST(nixsysconfdir)
-AC_SUBST(nixstoredir)
-
 # Expand all variables in config.status.
 test "$prefix" = NONE && prefix=$ac_default_prefix
 test "$exec_prefix" = NONE && exec_prefix='${prefix}'

perl/lib/Nix/Config.pm.in

@@ -4,14 +4,8 @@ use MIME::Base64;
 
 $version = "@PACKAGE_VERSION@";
 
-$binDir = $ENV{"NIX_BIN_DIR"} || "@nixbindir@";
+$binDir = Nix::Store::getBinDir;
-$libexecDir = $ENV{"NIX_LIBEXEC_DIR"} || "@nixlibexecdir@";
+$storeDir = Nix::Store::getStoreDir;
-$stateDir = $ENV{"NIX_STATE_DIR"} || "@nixlocalstatedir@/nix";
-$logDir = $ENV{"NIX_LOG_DIR"} || "@nixlocalstatedir@/log/nix";
-$confDir = $ENV{"NIX_CONF_DIR"} || "@nixsysconfdir@/nix";
-$storeDir = $ENV{"NIX_STORE_DIR"} || "@nixstoredir@";
-
-$useBindings = 1;
 
 %config = ();
 

perl/lib/Nix/Store.pm

@@ -2,7 +2,6 @@ package Nix::Store;
 
 use strict;
 use warnings;
-use Nix::Config;
 
 require Exporter;
 
@@ -22,6 +21,7 @@ our @EXPORT = qw(
     addToStore makeFixedOutputPath
     derivationFromPath
     addTempRoot
+    getBinDir getStoreDir
 );
 
 our $VERSION = '0.15';
@@ -34,62 +34,8 @@ sub backtick {
     return $res;
 }
 
-if ($Nix::Config::useBindings) {
+require XSLoader;
-    require XSLoader;
+XSLoader::load('Nix::Store', $VERSION);
-    XSLoader::load('Nix::Store', $VERSION);
-} else {
-
-    # Provide slow fallbacks of some functions on platforms that don't
-    # support the Perl bindings.
-
-    use File::Temp;
-    use Fcntl qw/F_SETFD/;
-
-    *hashFile = sub {
-        my ($algo, $base32, $path) = @_;
-        my $res = backtick("$Nix::Config::binDir/nix-hash", "--flat", $path, "--type", $algo, $base32 ? "--base32" : ());
-        chomp $res;
-        return $res;
-    };
-
-    *hashPath = sub {
-        my ($algo, $base32, $path) = @_;
-        my $res = backtick("$Nix::Config::binDir/nix-hash", $path, "--type", $algo, $base32 ? "--base32" : ());
-        chomp $res;
-        return $res;
-    };
-
-    *hashString = sub {
-        my ($algo, $base32, $s) = @_;
-        my $fh = File::Temp->new();
-        print $fh $s;
-        my $res = backtick("$Nix::Config::binDir/nix-hash", $fh->filename, "--type", $algo, $base32 ? "--base32" : ());
-        chomp $res;
-        return $res;
-    };
-
-    *addToStore = sub {
-        my ($srcPath, $recursive, $algo) = @_;
-        die "not implemented" if $recursive || $algo ne "sha256";
-        my $res = backtick("$Nix::Config::binDir/nix-store", "--add", $srcPath);
-        chomp $res;
-        return $res;
-    };
-
-    *isValidPath = sub {
-        my ($path) = @_;
-        my $res = backtick("$Nix::Config::binDir/nix-store", "--check-validity", "--print-invalid", $path);
-        chomp $res;
-        return $res ne $path;
-    };
-
-    *queryPathHash = sub {
-        my ($path) = @_;
-        my $res = backtick("$Nix::Config::binDir/nix-store", "--query", "--hash", $path);
-        chomp $res;
-        return $res;
-    };
-}
 
 1;
 __END__

perl/lib/Nix/Store.xs

@@ -351,3 +351,13 @@ void addTempRoot(char * storePath)
         } catch (Error & e) {
             croak("%s", e.what());
         }
+
+
+SV * getBinDir()
+    PPCODE:
+        XPUSHs(sv_2mortal(newSVpv(settings.nixBinDir.c_str(), 0)));
+
+
+SV * getStoreDir()
+    PPCODE:
+        XPUSHs(sv_2mortal(newSVpv(settings.nixStore.c_str(), 0)));

src/libexpr/common-eval-args.cc

@@ -76,7 +76,7 @@ Path lookupFileArg(EvalState & state, string s)
     if (isUri(s)) {
         return state.store->toRealPath(
             fetchers::downloadTarball(
-                state.store, resolveUri(s), Headers {}, "source", false).first.storePath);
+                state.store, resolveUri(s), "source", false).first.storePath);
     } else if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
         Path p = s.substr(1, s.size() - 2);
         return state.findFile(p);

src/libexpr/eval.cc

@@ -356,6 +356,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sEpsilon(symbols.create(""))
     , repair(NoRepair)
     , store(store)
+    , regexCache(makeRegexCache())
     , baseEnv(allocEnv(128))
     , staticBaseEnv(false, 0)
 {

src/libexpr/eval.hh

@@ -6,7 +6,6 @@
 #include "symbol-table.hh"
 #include "config.hh"
 
-#include <regex>
 #include <map>
 #include <optional>
 #include <unordered_map>
@@ -65,6 +64,11 @@ typedef std::list<SearchPathElem> SearchPath;
 void initGC();
 
 
+struct RegexCache;
+
+std::shared_ptr<RegexCache> makeRegexCache();
+
+
 class EvalState
 {
 public:
@@ -120,7 +124,7 @@ private:
     std::unordered_map<Path, Path> resolvedPaths;
 
     /* Cache used by prim_match(). */
-    std::unordered_map<std::string, std::regex> regexCache;
+    std::shared_ptr<RegexCache> regexCache;
 
 public:
 

src/libexpr/flake/flake.cc

@@ -48,17 +48,17 @@ static std::tuple<fetchers::Tree, FlakeRef, FlakeRef> fetchOrSubstituteTree(
                 resolvedRef = originalRef.resolve(state.store);
                 auto fetchedResolved = lookupInFlakeCache(flakeCache, originalRef);
                 if (!fetchedResolved) fetchedResolved.emplace(resolvedRef.fetchTree(state.store));
-                flakeCache.push_back({resolvedRef, fetchedResolved.value()});
+                flakeCache.push_back({resolvedRef, *fetchedResolved});
-                fetched.emplace(fetchedResolved.value());
+                fetched.emplace(*fetchedResolved);
             }
             else {
                 throw Error("'%s' is an indirect flake reference, but registry lookups are not allowed", originalRef);
             }
         }
-        flakeCache.push_back({originalRef, fetched.value()});
+        flakeCache.push_back({originalRef, *fetched});
     }
 
-    auto [tree, lockedRef] = fetched.value();
+    auto [tree, lockedRef] = *fetched;
 
     debug("got tree '%s' from '%s'",
         state.store->printStorePath(tree.storePath), lockedRef);
@@ -215,10 +215,9 @@ static Flake getFlake(
 
     if (auto outputs = vInfo.attrs->get(sOutputs)) {
         expectType(state, tLambda, *outputs->value, *outputs->pos);
-        flake.vOutputs = allocRootValue(outputs->value);
 
-        if ((*flake.vOutputs)->lambda.fun->matchAttrs) {
+        if (outputs->value->lambda.fun->matchAttrs) {
-            for (auto & formal : (*flake.vOutputs)->lambda.fun->formals->formals) {
+            for (auto & formal : outputs->value->lambda.fun->formals->formals) {
                 if (formal.name != state.sSelf)
                     flake.inputs.emplace(formal.name, FlakeInput {
                         .ref = parseFlakeRef(formal.name)
@@ -248,7 +247,7 @@ Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup
 }
 
 /* Compute an in-memory lock file for the specified top-level flake,
-   and optionally write it to file, it the flake is writable. */
+   and optionally write it to file, if the flake is writable. */
 LockedFlake lockFlake(
     EvalState & state,
     const FlakeRef & topRef,
@@ -367,7 +366,7 @@ LockedFlake lockFlake(
 
                 /* If we have an --update-input flag for an input
                    of this input, then we must fetch the flake to
-                   to update it. */
+                   update it. */
                 auto lb = lockFlags.inputUpdates.lower_bound(inputPath);
 
                 auto hasChildUpdate =

src/libexpr/flake/flake.hh

@@ -34,7 +34,6 @@ struct Flake
     std::optional<std::string> description;
     std::shared_ptr<const fetchers::Tree> sourceInfo;
     FlakeInputs inputs;
-    RootValue vOutputs;
     ~Flake();
 };
 

src/libexpr/flake/flakeref.cc

@@ -1,6 +1,7 @@
 #include "flakeref.hh"
 #include "store-api.hh"
 #include "url.hh"
+#include "url-parts.hh"
 #include "fetchers.hh"
 #include "registry.hh"
 

src/libexpr/flake/lockfile.cc

@@ -1,5 +1,6 @@
 #include "lockfile.hh"
 #include "store-api.hh"
+#include "url-parts.hh"
 
 #include <nlohmann/json.hpp>
 

src/libexpr/json-to-value.cc

@@ -115,6 +115,14 @@ public:
     {
         return handle_value<void(Value&, const char*)>(mkString, val.c_str());
     }
+#if NLOHMANN_JSON_VERSION_MAJOR >= 3 && NLOHMANN_JSON_VERSION_MINOR >= 8
+    bool binary(binary_t&)
+    {
+        // This function ought to be unreachable
+        assert(false);
+        return true;
+    }
+#endif
 
     bool start_object(std::size_t len)
     {

src/libexpr/local.mk

@@ -42,6 +42,6 @@ $(eval $(call install-file-in, $(d)/nix-expr.pc, $(prefix)/lib/pkgconfig, 0644))
 $(foreach i, $(wildcard src/libexpr/flake/*.hh), \
   $(eval $(call install-file-in, $(i), $(includedir)/nix/flake, 0644)))
 
-$(d)/primops.cc: $(d)/imported-drv-to-derivation.nix.gen.hh
+$(d)/primops.cc: $(d)/imported-drv-to-derivation.nix.gen.hh $(d)/primops/derivation.nix.gen.hh
 
 $(d)/flake/flake.cc: $(d)/flake/call-flake.nix.gen.hh

src/libexpr/parser.y

@@ -614,8 +614,7 @@ Path resolveExprPath(Path path)
         // Basic cycle/depth limit to avoid infinite loops.
         if (++followCount >= maxFollow)
             throw Error("too many symbolic links encountered while traversing the path '%s'", path);
-        if (lstat(path.c_str(), &st))
+        st = lstat(path);
-            throw SysError("getting status of '%s'", path);
         if (!S_ISLNK(st.st_mode)) break;
         path = absPath(readLink(path), dirOf(path));
     }
@@ -719,7 +718,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
     if (isUri(elem.second)) {
         try {
             res = { true, store->toRealPath(fetchers::downloadTarball(
-                        store, resolveUri(elem.second), Headers {}, "source", false).first.storePath) };
+                        store, resolveUri(elem.second), "source", false).first.storePath) };
         } catch (FileTransferError & e) {
             logWarning({
                 .name = "Entry download",

src/libexpr/primops.cc

@@ -2236,6 +2236,10 @@ static RegisterPrimOp primop_catAttrs({
 static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
+    if (args[0]->type == tPrimOpApp || args[0]->type == tPrimOp) {
+        state.mkAttrs(v, 0);
+        return;
+    }
     if (args[0]->type != tLambda)
         throw TypeError({
             .hint = hintfmt("'functionArgs' requires a function"),
@@ -3085,17 +3089,25 @@ static RegisterPrimOp primop_hashString({
     .fun = prim_hashString,
 });
 
-/* Match a regular expression against a string and return either
+struct RegexCache
-   ‘null’ or a list containing substring matches. */
+{
+    std::unordered_map<std::string, std::regex> cache;
+};
+
+std::shared_ptr<RegexCache> makeRegexCache()
+{
+    return std::make_shared<RegexCache>();
+}
+
 void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     auto re = state.forceStringNoCtx(*args[0], pos);
 
     try {
 
-        auto regex = state.regexCache.find(re);
+        auto regex = state.regexCache->cache.find(re);
-        if (regex == state.regexCache.end())
+        if (regex == state.regexCache->cache.end())
-            regex = state.regexCache.emplace(re, std::regex(re, std::regex::extended)).first;
+            regex = state.regexCache->cache.emplace(re, std::regex(re, std::regex::extended)).first;
 
         PathSet context;
         const std::string str = state.forceString(*args[1], context, pos);
@@ -3565,13 +3577,11 @@ void EvalState::createBaseEnv()
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */
-    try {
+    sDerivationNix = symbols.create("//builtin/derivation.nix");
-        string path = canonPath(settings.nixDataDir + "/nix/corepkgs/derivation.nix", true);
+    eval(parse(
-        sDerivationNix = symbols.create(path);
+        #include "primops/derivation.nix.gen.hh"
-        evalFile(path, v);
+        , foFile, sDerivationNix, "/", staticBaseEnv), v);
     addConstant("derivation", v);
-    } catch (SysError &) {
-    }
 
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */

src/libexpr/primops/fetchMercurial.cc

@@ -3,8 +3,7 @@
 #include "store-api.hh"
 #include "fetchers.hh"
 #include "url.hh"
-
+#include "url-parts.hh"
-#include <regex>
 
 namespace nix {
 

src/libexpr/primops/fetchTree.cc

@@ -201,8 +201,8 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
 
     auto storePath =
         unpack
-        ? fetchers::downloadTarball(state.store, *url, Headers {}, name, (bool) expectedHash).first.storePath
+        ? fetchers::downloadTarball(state.store, *url, name, (bool) expectedHash).first.storePath
-        : fetchers::downloadFile(state.store, *url, Headers{}, name, (bool) expectedHash).storePath;
+        : fetchers::downloadFile(state.store, *url, name, (bool) expectedHash).storePath;
 
     auto path = state.store->toRealPath(storePath);
 

src/libfetchers/fetchers.hh

@@ -73,7 +73,7 @@ public:
 
     StorePath computeStorePath(Store & store) const;
 
-    // Convience functions for common attributes.
+    // Convenience functions for common attributes.
     std::string getType() const;
     std::optional<Hash> getNarHash() const;
     std::optional<std::string> getRef() const;
@@ -118,15 +118,15 @@ struct DownloadFileResult
 DownloadFileResult downloadFile(
     ref<Store> store,
     const std::string & url,
-    const Headers & headers,
     const std::string & name,
-    bool immutable);
+    bool immutable,
+    const Headers & headers = {});
 
 std::pair<Tree, time_t> downloadTarball(
     ref<Store> store,
     const std::string & url,
-    const Headers & headers,
     const std::string & name,
-    bool immutable);
+    bool immutable,
+    const Headers & headers = {});
 
 }

src/libfetchers/git.cc

@@ -3,6 +3,7 @@
 #include "globals.hh"
 #include "tarfile.hh"
 #include "store-api.hh"
+#include "url-parts.hh"
 
 #include <sys/time.h>
 

src/libfetchers/github.cc

@@ -4,6 +4,7 @@
 #include "globals.hh"
 #include "store-api.hh"
 #include "types.hh"
+#include "url-parts.hh"
 
 #include <optional>
 #include <nlohmann/json.hpp>
@@ -19,9 +20,9 @@ struct DownloadUrl
         : url(url), headers(headers) { }
 };
 
-// A github or gitlab url
+// A github or gitlab host
-const static std::string urlRegexS = "[a-zA-Z0-9.]*"; // FIXME: check
+const static std::string hostRegexS = "[a-zA-Z0-9.]*"; // FIXME: check
-std::regex urlRegex(urlRegexS, std::regex::ECMAScript);
+std::regex hostRegex(hostRegexS, std::regex::ECMAScript);
 
 struct GitArchiveInputScheme : InputScheme
 {
@@ -64,7 +65,7 @@ struct GitArchiveInputScheme : InputScheme
                 ref = value;
             }
             else if (name == "host") {
-                if (!std::regex_match(value, urlRegex))
+                if (!std::regex_match(value, hostRegex))
                     throw BadURL("URL '%s' contains an invalid instance host", url.url);
                 host_url = value;
             }
@@ -204,7 +205,7 @@ struct GitArchiveInputScheme : InputScheme
 
         auto url = getDownloadUrl(input);
 
-        auto [tree, lastModified] = downloadTarball(store, url.url, url.headers, "source", true);
+        auto [tree, lastModified] = downloadTarball(store, url.url, "source", true, url.headers);
 
         input.attrs.insert_or_assign("lastModified", lastModified);
 
@@ -247,7 +248,7 @@ struct GitHubInputScheme : GitArchiveInputScheme
         auto json = nlohmann::json::parse(
             readFile(
                 store->toRealPath(
-                    downloadFile(store, url, headers, "source", false).storePath)));
+                    downloadFile(store, url, "source", false, headers).storePath)));
         auto rev = Hash::parseAny(std::string { json["sha"] }, htSHA1);
         debug("HEAD revision for '%s' is %s", url, rev.gitRev());
         return rev;
@@ -310,7 +311,7 @@ struct GitLabInputScheme : GitArchiveInputScheme
         auto json = nlohmann::json::parse(
             readFile(
                 store->toRealPath(
-                    downloadFile(store, url, headers, "source", false).storePath)));
+                    downloadFile(store, url, "source", false, headers).storePath)));
         auto rev = Hash::parseAny(std::string(json[0]["id"]), htSHA1);
         debug("HEAD revision for '%s' is %s", url, rev.gitRev());
         return rev;

src/libfetchers/indirect.cc

@@ -1,4 +1,5 @@
 #include "fetchers.hh"
+#include "url-parts.hh"
 
 namespace nix::fetchers {
 

src/libfetchers/mercurial.cc

@@ -3,6 +3,7 @@
 #include "globals.hh"
 #include "tarfile.hh"
 #include "store-api.hh"
+#include "url-parts.hh"
 
 #include <sys/time.h>
 

src/libfetchers/registry.cc

@@ -145,7 +145,7 @@ static std::shared_ptr<Registry> getGlobalRegistry(ref<Store> store)
         auto path = settings.flakeRegistry.get();
 
         if (!hasPrefix(path, "/")) {
-            auto storePath = downloadFile(store, path, Headers {}, "flake-registry.json", false).storePath;
+            auto storePath = downloadFile(store, path, "flake-registry.json", false).storePath;
             if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>())
                 store2->addPermRoot(storePath, getCacheDir() + "/nix/flake-registry.json");
             path = store->toRealPath(storePath);

src/libfetchers/tarball.cc

@@ -12,9 +12,9 @@ namespace nix::fetchers {
 DownloadFileResult downloadFile(
     ref<Store> store,
     const std::string & url,
-    const Headers & headers,
     const std::string & name,
-    bool immutable)
+    bool immutable,
+    const Headers & headers)
 {
     // FIXME: check store
 
@@ -38,7 +38,8 @@ DownloadFileResult downloadFile(
     if (cached && !cached->expired)
         return useCached();
 
-    FileTransferRequest request(url, headers);
+    FileTransferRequest request(url);
+    request.headers = headers;
     if (cached)
         request.expectedETag = getStrAttr(cached->infoAttrs, "etag");
     FileTransferResult res;
@@ -112,9 +113,9 @@ DownloadFileResult downloadFile(
 std::pair<Tree, time_t> downloadTarball(
     ref<Store> store,
     const std::string & url,
-    const Headers & headers,
     const std::string & name,
-    bool immutable)
+    bool immutable,
+    const Headers & headers)
 {
     Attrs inAttrs({
         {"type", "tarball"},
@@ -130,7 +131,7 @@ std::pair<Tree, time_t> downloadTarball(
             getIntAttr(cached->infoAttrs, "lastModified")
         };
 
-    auto res = downloadFile(store, url, headers, name, immutable);
+    auto res = downloadFile(store, url, name, immutable, headers);
 
     std::optional<StorePath> unpackedStorePath;
     time_t lastModified;
@@ -225,7 +226,7 @@ struct TarballInputScheme : InputScheme
 
     std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) override
     {
-        auto tree = downloadTarball(store, getStrAttr(input.attrs, "url"), Headers {}, "source", false).first;
+        auto tree = downloadTarball(store, getStrAttr(input.attrs, "url"), "source", false).first;
         return {std::move(tree), input};
     }
 };

src/libmain/progress-bar.cc

@@ -256,7 +256,7 @@ public:
         }
 
         else if (type == resBuildLogLine || type == resPostBuildLogLine) {
-            auto lastLine = trim(getS(fields, 0));
+            auto lastLine = chomp(getS(fields, 0));
             if (!lastLine.empty()) {
                 auto i = state->its.find(act);
                 assert(i != state->its.end());

src/libstore/binary-cache-store.cc

@@ -11,6 +11,7 @@
 #include "nar-accessor.hh"
 #include "json.hh"
 #include "thread-pool.hh"
+#include "callback.hh"
 
 #include <chrono>
 #include <future>

src/libstore/build.cc

@@ -17,6 +17,7 @@
 #include "daemon.hh"
 #include "worker-protocol.hh"
 #include "topo-sort.hh"
+#include "callback.hh"
 
 #include <algorithm>
 #include <iostream>
@@ -295,9 +296,21 @@ public:
     ~Worker();
 
     /* Make a goal (with caching). */
-    GoalPtr makeDerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
+
-    std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(const StorePath & drvPath,
+    /* derivation goal */
-        const BasicDerivation & drv, BuildMode buildMode = bmNormal);
+private:
+    std::shared_ptr<DerivationGoal> makeDerivationGoalCommon(
+        const StorePath & drvPath, const StringSet & wantedOutputs,
+        std::function<std::shared_ptr<DerivationGoal>()> mkDrvGoal);
+public:
+    std::shared_ptr<DerivationGoal> makeDerivationGoal(
+        const StorePath & drvPath,
+        const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
+    std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(
+        const StorePath & drvPath, const BasicDerivation & drv,
+        const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
+
+    /* substitution goal */
     GoalPtr makeSubstitutionGoal(const StorePath & storePath, RepairFlag repair = NoRepair, std::optional<ContentAddress> ca = std::nullopt);
 
     /* Remove a dead goal. */
@@ -948,10 +961,12 @@ private:
     friend struct RestrictedStore;
 
 public:
-    DerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs,
+    DerivationGoal(const StorePath & drvPath,
-        Worker & worker, BuildMode buildMode = bmNormal);
+        const StringSet & wantedOutputs, Worker & worker,
+        BuildMode buildMode = bmNormal);
     DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
-        Worker & worker, BuildMode buildMode = bmNormal);
+        const StringSet & wantedOutputs, Worker & worker,
+        BuildMode buildMode = bmNormal);
     ~DerivationGoal();
 
     /* Whether we need to perform hash rewriting if there are valid output paths. */
@@ -993,6 +1008,8 @@ private:
     void tryLocalBuild();
     void buildDone();
 
+    void resolvedFinished();
+
     /* Is the build hook willing to perform the build? */
     HookReply tryBuildHook();
 
@@ -1084,8 +1101,8 @@ private:
 const Path DerivationGoal::homeDir = "/homeless-shelter";
 
 
-DerivationGoal::DerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs,
+DerivationGoal::DerivationGoal(const StorePath & drvPath,
-    Worker & worker, BuildMode buildMode)
+    const StringSet & wantedOutputs, Worker & worker, BuildMode buildMode)
     : Goal(worker)
     , useDerivation(true)
     , drvPath(drvPath)
@@ -1093,7 +1110,9 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath, const StringSet & want
     , buildMode(buildMode)
 {
     state = &DerivationGoal::getDerivation;
-    name = fmt("building of '%s'", worker.store.printStorePath(this->drvPath));
+    name = fmt(
+        "building of '%s' from .drv file",
+        StorePathWithOutputs { drvPath, wantedOutputs }.to_string(worker.store));
     trace("created");
 
     mcExpectedBuilds = std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds);
@@ -1102,15 +1121,18 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath, const StringSet & want
 
 
 DerivationGoal::DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
-    Worker & worker, BuildMode buildMode)
+    const StringSet & wantedOutputs, Worker & worker, BuildMode buildMode)
     : Goal(worker)
     , useDerivation(false)
     , drvPath(drvPath)
+    , wantedOutputs(wantedOutputs)
     , buildMode(buildMode)
 {
     this->drv = std::make_unique<BasicDerivation>(BasicDerivation(drv));
     state = &DerivationGoal::haveDerivation;
-    name = fmt("building of %s", StorePathWithOutputs { drvPath, drv.outputNames() }.to_string(worker.store));
+    name = fmt(
+        "building of '%s' from in-memory derivation",
+        StorePathWithOutputs { drvPath, drv.outputNames() }.to_string(worker.store));
     trace("created");
 
     mcExpectedBuilds = std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds);
@@ -1463,8 +1485,40 @@ void DerivationGoal::inputsRealised()
     /* Determine the full set of input paths. */
 
     /* First, the input derivations. */
-    if (useDerivation)
+    if (useDerivation) {
-        for (auto & [depDrvPath, wantedDepOutputs] : dynamic_cast<Derivation *>(drv.get())->inputDrvs) {
+        auto & fullDrv = *dynamic_cast<Derivation *>(drv.get());
+
+        if (!fullDrv.inputDrvs.empty() && fullDrv.type() == DerivationType::CAFloating) {
+            /* We are be able to resolve this derivation based on the
+               now-known results of dependencies. If so, we become a stub goal
+               aliasing that resolved derivation goal */
+            std::optional attempt = fullDrv.tryResolve(worker.store);
+            assert(attempt);
+            Derivation drvResolved { *std::move(attempt) };
+
+            auto pathResolved = writeDerivation(worker.store, drvResolved);
+            /* Add to memotable to speed up downstream goal's queries with the
+               original derivation. */
+            drvPathResolutions.lock()->insert_or_assign(drvPath, pathResolved);
+
+            auto msg = fmt("Resolved derivation: '%s' -> '%s'",
+                worker.store.printStorePath(drvPath),
+                worker.store.printStorePath(pathResolved));
+            act = std::make_unique<Activity>(*logger, lvlInfo, actBuildWaiting, msg,
+                Logger::Fields {
+                       worker.store.printStorePath(drvPath),
+                       worker.store.printStorePath(pathResolved),
+                   });
+
+            auto resolvedGoal = worker.makeDerivationGoal(
+                pathResolved, wantedOutputs, buildMode);
+            addWaitee(resolvedGoal);
+
+            state = &DerivationGoal::resolvedFinished;
+            return;
+        }
+
+        for (auto & [depDrvPath, wantedDepOutputs] : fullDrv.inputDrvs) {
             /* Add the relevant output closures of the input derivation
                `i' as input paths.  Only add the closures of output paths
                that are specified as inputs. */
@@ -1484,6 +1538,7 @@ void DerivationGoal::inputsRealised()
                         worker.store.printStorePath(drvPath), j, worker.store.printStorePath(drvPath));
             }
         }
+    }
 
     /* Second, the input sources. */
     worker.store.computeFSClosure(drv->inputSrcs, inputPaths);
@@ -1611,6 +1666,13 @@ void DerivationGoal::tryToBuild()
 
     actLock.reset();
 
+    state = &DerivationGoal::tryLocalBuild;
+    worker.wakeUp(shared_from_this());
+}
+
+void DerivationGoal::tryLocalBuild() {
+    bool buildLocally = buildMode != bmNormal || parsedDrv->willBuildLocally(worker.store);
+
     /* Make sure that we are allowed to start a build.  If this
        derivation prefers to be done locally, do it even if
        maxBuildJobs is 0. */
@@ -1621,12 +1683,6 @@ void DerivationGoal::tryToBuild()
         return;
     }
 
-    state = &DerivationGoal::tryLocalBuild;
-    worker.wakeUp(shared_from_this());
-}
-
-void DerivationGoal::tryLocalBuild() {
-
     /* If `build-users-group' is not empty, then we have to build as
        one of the members of that group. */
     if (settings.buildUsersGroup != "" && getuid() == 0) {
@@ -1674,7 +1730,34 @@ void DerivationGoal::tryLocalBuild() {
 }
 
 
-void replaceValidPath(const Path & storePath, const Path tmpPath)
+static void chmod_(const Path & path, mode_t mode)
+{
+    if (chmod(path.c_str(), mode) == -1)
+        throw SysError("setting permissions on '%s'", path);
+}
+
+
+/* Move/rename path 'src' to 'dst'. Temporarily make 'src' writable if
+   it's a directory and we're not root (to be able to update the
+   directory's parent link ".."). */
+static void movePath(const Path & src, const Path & dst)
+{
+    auto st = lstat(src);
+
+    bool changePerm = (geteuid() && S_ISDIR(st.st_mode) && !(st.st_mode & S_IWUSR));
+
+    if (changePerm)
+        chmod_(src, st.st_mode | S_IWUSR);
+
+    if (rename(src.c_str(), dst.c_str()))
+        throw SysError("renaming '%1%' to '%2%'", src, dst);
+
+    if (changePerm)
+        chmod_(dst, st.st_mode);
+}
+
+
+void replaceValidPath(const Path & storePath, const Path & tmpPath)
 {
     /* We can't atomically replace storePath (the original) with
        tmpPath (the replacement), so we have to move it out of the
@@ -1682,11 +1765,20 @@ void replaceValidPath(const Path & storePath, const Path tmpPath)
        we're repairing (say) Glibc, we end up with a broken system. */
     Path oldPath = (format("%1%.old-%2%-%3%") % storePath % getpid() % random()).str();
     if (pathExists(storePath))
-        rename(storePath.c_str(), oldPath.c_str());
+        movePath(storePath, oldPath);
-    if (rename(tmpPath.c_str(), storePath.c_str()) == -1) {
+
-        rename(oldPath.c_str(), storePath.c_str()); // attempt to recover
+    try {
-        throw SysError("moving '%s' to '%s'", tmpPath, storePath);
+        movePath(tmpPath, storePath);
+    } catch (...) {
+        try {
+            // attempt to recover
+            movePath(oldPath, storePath);
+        } catch (...) {
+            ignoreException();
         }
+        throw;
+    }
+
     deletePath(oldPath);
 }
 
@@ -1905,6 +1997,9 @@ void DerivationGoal::buildDone()
     done(BuildResult::Built);
 }
 
+void DerivationGoal::resolvedFinished() {
+    done(BuildResult::Built);
+}
 
 HookReply DerivationGoal::tryBuildHook()
 {
@@ -2004,13 +2099,6 @@ HookReply DerivationGoal::tryBuildHook()
 }
 
 
-static void chmod_(const Path & path, mode_t mode)
-{
-    if (chmod(path.c_str(), mode) == -1)
-        throw SysError("setting permissions on '%s'", path);
-}
-
-
 int childEntry(void * arg)
 {
     ((DerivationGoal *) arg)->runChild();
@@ -2366,10 +2454,7 @@ void DerivationGoal::startBuilder()
         for (auto & i : inputPaths) {
             auto p = worker.store.printStorePath(i);
             Path r = worker.store.toRealPath(p);
-            struct stat st;
+            if (S_ISDIR(lstat(r).st_mode))
-            if (lstat(r.c_str(), &st))
-                throw SysError("getting attributes of path '%s'", p);
-            if (S_ISDIR(st.st_mode))
                 dirsInChroot.insert_or_assign(p, r);
             else
                 linkOrCopy(r, chrootRootDir + p);
@@ -2949,14 +3034,6 @@ struct RestrictedStore : public LocalFSStore, public virtual RestrictedStoreConf
         goal.addDependency(info.path);
     }
 
-    StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override
-    {
-        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair);
-        goal.addDependency(path);
-        return path;
-    }
-
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair = NoRepair) override
     {
@@ -3151,9 +3228,7 @@ void DerivationGoal::addDependency(const StorePath & path)
             if (pathExists(target))
                 throw Error("store path '%s' already exists in the sandbox", worker.store.printStorePath(path));
 
-            struct stat st;
+            auto st = lstat(source);
-            if (lstat(source.c_str(), &st))
-                throw SysError("getting attributes of path '%s'", source);
 
             if (S_ISDIR(st.st_mode)) {
 
@@ -3742,29 +3817,6 @@ void DerivationGoal::runChild()
 }
 
 
-static void moveCheckToStore(const Path & src, const Path & dst)
-{
-    /* For the rename of directory to succeed, we must be running as root or
-       the directory must be made temporarily writable (to update the
-       directory's parent link ".."). */
-    struct stat st;
-    if (lstat(src.c_str(), &st) == -1) {
-        throw SysError("getting attributes of path '%1%'", src);
-    }
-
-    bool changePerm = (geteuid() && S_ISDIR(st.st_mode) && !(st.st_mode & S_IWUSR));
-
-    if (changePerm)
-        chmod_(src, st.st_mode | S_IWUSR);
-
-    if (rename(src.c_str(), dst.c_str()))
-        throw SysError("renaming '%1%' to '%2%'", src, dst);
-
-    if (changePerm)
-        chmod_(dst, st.st_mode);
-}
-
-
 void DerivationGoal::registerOutputs()
 {
     /* When using a build hook, the build hook can register the output
@@ -3865,7 +3917,7 @@ void DerivationGoal::registerOutputs()
            something like that. */
         canonicalisePathMetaData(actualPath, buildUser ? buildUser->getUID() : -1, inodesSeen);
 
-        debug("scanning for references for output %1 in temp location '%1%'", outputName, actualPath);
+        debug("scanning for references for output '%s' in temp location '%s'", outputName, actualPath);
 
         /* Pass blank Sink as we are not ready to hash data at this stage. */
         NullSink blank;
@@ -3920,7 +3972,6 @@ void DerivationGoal::registerOutputs()
                 outputRewrites[std::string { scratchPath.hashPart() }] = std::string { finalStorePath.hashPart() };
         };
 
-        bool rewritten = false;
         std::optional<StorePathSet> referencesOpt = std::visit(overloaded {
             [&](AlreadyRegistered skippedFinalPath) -> std::optional<StorePathSet> {
                 finish(skippedFinalPath.path);
@@ -3951,7 +4002,9 @@ void DerivationGoal::registerOutputs()
                 StringSource source(*sink.s);
                 restorePath(actualPath, source);
 
-                rewritten = true;
+                /* FIXME: set proper permissions in restorePath() so
+                   we don't have to do another traversal. */
+                canonicalisePathMetaData(actualPath, -1, inodesSeen);
             }
         };
 
@@ -4034,7 +4087,7 @@ void DerivationGoal::registerOutputs()
             [&](DerivationOutputInputAddressed output) {
                 /* input-addressed case */
                 auto requiredFinalPath = output.path;
-                /* Preemtively add rewrite rule for final hash, as that is
+                /* Preemptively add rewrite rule for final hash, as that is
                    what the NAR hash will use rather than normalized-self references */
                 if (scratchPath != requiredFinalPath)
                     outputRewrites.insert_or_assign(
@@ -4108,44 +4161,21 @@ void DerivationGoal::registerOutputs()
                    else. No moving needed. */
                 assert(newInfo.ca);
             } else {
-                /* Temporarily add write perm so we can move, will be fixed
+                auto destPath = worker.store.toRealPath(finalDestPath);
-                   later. */
+                movePath(actualPath, destPath);
-                {
+                actualPath = destPath;
-                    struct stat st;
-                    auto & mode = st.st_mode;
-                    if (lstat(actualPath.c_str(), &st))
-                        throw SysError("getting attributes of path '%1%'", actualPath);
-                    mode |= 0200;
-                    /* Try to change the perms, but only if the file isn't a
-                       symlink as symlinks permissions are mostly ignored and
-                       calling `chmod` on it will just forward the call to the
-                       target of the link. */
-                    if (!S_ISLNK(st.st_mode))
-                        if (chmod(actualPath.c_str(), mode) == -1)
-                            throw SysError("changing mode of '%1%' to %2$o", actualPath, mode);
-                }
-                if (rename(
-                        actualPath.c_str(),
-                        worker.store.toRealPath(finalDestPath).c_str()) == -1)
-                    throw SysError("moving build output '%1%' from it's temporary location to the Nix store", finalDestPath);
-                actualPath = worker.store.toRealPath(finalDestPath);
             }
         }
 
-        /* Get rid of all weird permissions.  This also checks that
-           all files are owned by the build user, if applicable. */
-        canonicalisePathMetaData(actualPath,
-            buildUser && !rewritten ? buildUser->getUID() : -1, inodesSeen);
-
         if (buildMode == bmCheck) {
             if (!worker.store.isValidPath(newInfo.path)) continue;
             ValidPathInfo oldInfo(*worker.store.queryPathInfo(newInfo.path));
             if (newInfo.narHash != oldInfo.narHash) {
                 worker.checkMismatch = true;
                 if (settings.runDiffHook || settings.keepFailed) {
-                    Path dst = worker.store.toRealPath(finalDestPath + checkSuffix);
+                    auto dst = worker.store.toRealPath(finalDestPath + checkSuffix);
                     deletePath(dst);
-                    moveCheckToStore(actualPath, dst);
+                    movePath(actualPath, dst);
 
                     handleDiffHook(
                         buildUser ? buildUser->getUID() : getuid(),
@@ -4265,11 +4295,13 @@ void DerivationGoal::registerOutputs()
     /* Register each output path as valid, and register the sets of
        paths referenced by each of them.  If there are cycles in the
        outputs, this will fail. */
+    {
         ValidPathInfos infos2;
         for (auto & [outputName, newInfo] : infos) {
             infos2.push_back(newInfo);
         }
         worker.store.registerValidPaths(infos2);
+    }
 
     /* In case of a fixed-output derivation hash mismatch, throw an
        exception now that we have registered the output as valid. */
@@ -4281,12 +4313,21 @@ void DerivationGoal::registerOutputs()
        means it's safe to link the derivation to the output hash. We must do
        that for floating CA derivations, which otherwise couldn't be cached,
        but it's fine to do in all cases. */
-    for (auto & [outputName, newInfo] : infos) {
+    bool isCaFloating = drv->type() == DerivationType::CAFloating;
-        /* FIXME: we will want to track this mapping in the DB whether or
+
-           not we have a drv file. */
+    auto drvPathResolved = drvPath;
-        if (useDerivation)
+    if (!useDerivation && isCaFloating) {
-            worker.store.linkDeriverToPath(drvPath, outputName, newInfo.path);
+        /* Once a floating CA derivations reaches this point, it
+           must already be resolved, so we don't bother trying to
+           downcast drv to get would would just be an empty
+           inputDrvs field. */
+        Derivation drv2 { *drv };
+        drvPathResolved = writeDerivation(worker.store, drv2);
     }
+
+    if (useDerivation || isCaFloating)
+        for (auto & [outputName, newInfo] : infos)
+            worker.store.linkDeriverToPath(drvPathResolved, outputName, newInfo.path);
 }
 
 
@@ -4576,7 +4617,7 @@ void DerivationGoal::flushLine()
 
 std::map<std::string, std::optional<StorePath>> DerivationGoal::queryPartialDerivationOutputMap()
 {
-    if (drv->type() != DerivationType::CAFloating) {
+    if (!useDerivation || drv->type() != DerivationType::CAFloating) {
         std::map<std::string, std::optional<StorePath>> res;
         for (auto & [name, output] : drv->outputs)
             res.insert_or_assign(name, output.path(worker.store, drv->name, name));
@@ -4588,7 +4629,7 @@ std::map<std::string, std::optional<StorePath>> DerivationGoal::queryPartialDeri
 
 OutputPathMap DerivationGoal::queryDerivationOutputMap()
 {
-    if (drv->type() != DerivationType::CAFloating) {
+    if (!useDerivation || drv->type() != DerivationType::CAFloating) {
         OutputPathMap res;
         for (auto & [name, output] : drv->outputsAndOptPaths(worker.store))
             res.insert_or_assign(name, *output.second);
@@ -5067,35 +5108,52 @@ Worker::~Worker()
 }
 
 
-GoalPtr Worker::makeDerivationGoal(const StorePath & path,
+std::shared_ptr<DerivationGoal> Worker::makeDerivationGoalCommon(
-    const StringSet & wantedOutputs, BuildMode buildMode)
+    const StorePath & drvPath,
+    const StringSet & wantedOutputs,
+    std::function<std::shared_ptr<DerivationGoal>()> mkDrvGoal)
 {
-    GoalPtr goal = derivationGoals[path].lock(); // FIXME
+    WeakGoalPtr & abstract_goal_weak = derivationGoals[drvPath];
-    if (!goal) {
+    GoalPtr abstract_goal = abstract_goal_weak.lock(); // FIXME
-        goal = std::make_shared<DerivationGoal>(path, wantedOutputs, *this, buildMode);
+    std::shared_ptr<DerivationGoal> goal;
-        derivationGoals.insert_or_assign(path, goal);
+    if (!abstract_goal) {
+        goal = mkDrvGoal();
+        abstract_goal_weak = goal;
         wakeUp(goal);
-    } else
+    } else {
-        (dynamic_cast<DerivationGoal *>(goal.get()))->addWantedOutputs(wantedOutputs);
+        goal = std::dynamic_pointer_cast<DerivationGoal>(abstract_goal);
+        assert(goal);
+        goal->addWantedOutputs(wantedOutputs);
+    }
     return goal;
 }
 
 
-std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(const StorePath & drvPath,
+std::shared_ptr<DerivationGoal> Worker::makeDerivationGoal(const StorePath & drvPath,
-    const BasicDerivation & drv, BuildMode buildMode)
+    const StringSet & wantedOutputs, BuildMode buildMode)
 {
-    auto goal = std::make_shared<DerivationGoal>(drvPath, drv, *this, buildMode);
+    return makeDerivationGoalCommon(drvPath, wantedOutputs, [&]() {
-    wakeUp(goal);
+        return std::make_shared<DerivationGoal>(drvPath, wantedOutputs, *this, buildMode);
-    return goal;
+    });
+}
+
+
+std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(const StorePath & drvPath,
+    const BasicDerivation & drv, const StringSet & wantedOutputs, BuildMode buildMode)
+{
+    return makeDerivationGoalCommon(drvPath, wantedOutputs, [&]() {
+        return std::make_shared<DerivationGoal>(drvPath, drv, wantedOutputs, *this, buildMode);
+    });
 }
 
 
 GoalPtr Worker::makeSubstitutionGoal(const StorePath & path, RepairFlag repair, std::optional<ContentAddress> ca)
 {
-    GoalPtr goal = substitutionGoals[path].lock(); // FIXME
+    WeakGoalPtr & goal_weak = substitutionGoals[path];
+    GoalPtr goal = goal_weak.lock(); // FIXME
     if (!goal) {
         goal = std::make_shared<SubstitutionGoal>(path, *this, repair, ca);
-        substitutionGoals.insert_or_assign(path, goal);
+        goal_weak = goal;
         wakeUp(goal);
     }
     return goal;
@@ -5526,7 +5584,7 @@ BuildResult LocalStore::buildDerivation(const StorePath & drvPath, const BasicDe
     BuildMode buildMode)
 {
     Worker worker(*this);
-    auto goal = worker.makeBasicDerivationGoal(drvPath, drv, buildMode);
+    auto goal = worker.makeBasicDerivationGoal(drvPath, drv, {}, buildMode);
 
     BuildResult result;
 

src/libstore/content-address.cc

@@ -4,11 +4,13 @@
 
 namespace nix {
 
-std::string FixedOutputHash::printMethodAlgo() const {
+std::string FixedOutputHash::printMethodAlgo() const
+{
     return makeFileIngestionPrefix(method) + printHashType(hash.type);
 }
 
-std::string makeFileIngestionPrefix(const FileIngestionMethod m) {
+std::string makeFileIngestionPrefix(const FileIngestionMethod m)
+{
     switch (m) {
     case FileIngestionMethod::Flat:
         return "";
@@ -26,7 +28,8 @@ std::string makeFixedOutputCA(FileIngestionMethod method, const Hash & hash)
         + hash.to_string(Base32, true);
 }
 
-std::string renderContentAddress(ContentAddress ca) {
+std::string renderContentAddress(ContentAddress ca)
+{
     return std::visit(overloaded {
         [](TextHash th) {
             return "text:" + th.hash.to_string(Base32, true);
@@ -37,54 +40,97 @@ std::string renderContentAddress(ContentAddress ca) {
     }, ca);
 }
 
-ContentAddress parseContentAddress(std::string_view rawCa) {
+std::string renderContentAddressMethod(ContentAddressMethod cam)
-    auto rest = rawCa;
+{
+    return std::visit(overloaded {
+        [](TextHashMethod &th) {
+            return std::string{"text:"} + printHashType(htSHA256);
+        },
+        [](FixedOutputHashMethod &fshm) {
+            return "fixed:" + makeFileIngestionPrefix(fshm.fileIngestionMethod) + printHashType(fshm.hashType);
+        }
+    }, cam);
+}
+
+/*
+  Parses content address strings up to the hash.
+ */
+static ContentAddressMethod parseContentAddressMethodPrefix(std::string_view & rest)
+{
+    std::string_view wholeInput { rest };
 
     std::string_view prefix;
     {
         auto optPrefix = splitPrefixTo(rest, ':');
         if (!optPrefix)
-            throw UsageError("not a content address because it is not in the form '<prefix>:<rest>': %s", rawCa);
+            throw UsageError("not a content address because it is not in the form '<prefix>:<rest>': %s", wholeInput);
         prefix = *optPrefix;
     }
 
     auto parseHashType_ = [&](){
         auto hashTypeRaw = splitPrefixTo(rest, ':');
         if (!hashTypeRaw)
-            throw UsageError("content address hash must be in form '<algo>:<hash>', but found: %s", rawCa);
+            throw UsageError("content address hash must be in form '<algo>:<hash>', but found: %s", wholeInput);
         HashType hashType = parseHashType(*hashTypeRaw);
         return std::move(hashType);
     };
 
     // Switch on prefix
     if (prefix == "text") {
-        // No parsing of the method, "text" only support flat.
+        // No parsing of the ingestion method, "text" only support flat.
         HashType hashType = parseHashType_();
         if (hashType != htSHA256)
             throw Error("text content address hash should use %s, but instead uses %s",
                 printHashType(htSHA256), printHashType(hashType));
-        return TextHash {
+        return TextHashMethod {};
-            .hash = Hash::parseNonSRIUnprefixed(rest, std::move(hashType)),
-        };
     } else if (prefix == "fixed") {
         // Parse method
         auto method = FileIngestionMethod::Flat;
         if (splitPrefix(rest, "r:"))
             method = FileIngestionMethod::Recursive;
         HashType hashType = parseHashType_();
-        return FixedOutputHash {
+        return FixedOutputHashMethod {
-            .method = method,
+            .fileIngestionMethod = method,
-            .hash = Hash::parseNonSRIUnprefixed(rest, std::move(hashType)),
+            .hashType = std::move(hashType),
         };
     } else
         throw UsageError("content address prefix '%s' is unrecognized. Recogonized prefixes are 'text' or 'fixed'", prefix);
+}
+
+ContentAddress parseContentAddress(std::string_view rawCa) {
+    auto rest = rawCa;
+
+    ContentAddressMethod caMethod = parseContentAddressMethodPrefix(rest);
+
+    return std::visit(
+        overloaded {
+            [&](TextHashMethod thm) {
+                return ContentAddress(TextHash {
+                    .hash = Hash::parseNonSRIUnprefixed(rest, htSHA256)
+                });
+            },
+            [&](FixedOutputHashMethod fohMethod) {
+                return ContentAddress(FixedOutputHash {
+                    .method = fohMethod.fileIngestionMethod,
+                    .hash = Hash::parseNonSRIUnprefixed(rest, std::move(fohMethod.hashType)),
+                });
+            },
+        }, caMethod);
+}
+
+ContentAddressMethod parseContentAddressMethod(std::string_view caMethod)
+{
+    std::string_view asPrefix {std::string{caMethod} + ":"};
+    return parseContentAddressMethodPrefix(asPrefix);
+}
+
+std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt)
+{
+    return rawCaOpt == "" ? std::optional<ContentAddress>() : parseContentAddress(rawCaOpt);
 };
 
-std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt) {
+std::string renderContentAddress(std::optional<ContentAddress> ca)
-    return rawCaOpt == "" ? std::optional<ContentAddress> {} : parseContentAddress(rawCaOpt);
+{
-};
-
-std::string renderContentAddress(std::optional<ContentAddress> ca) {
     return ca ? renderContentAddress(*ca) : "";
 }
 

src/libstore/content-address.hh

@@ -55,4 +55,23 @@ std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt);
 
 Hash getContentAddressHash(const ContentAddress & ca);
 
+/*
+  We only have one way to hash text with references, so this is single-value
+  type is only useful in std::variant.
+*/
+struct TextHashMethod { };
+struct FixedOutputHashMethod {
+  FileIngestionMethod fileIngestionMethod;
+  HashType hashType;
+};
+
+typedef std::variant<
+    TextHashMethod,
+    FixedOutputHashMethod
+  > ContentAddressMethod;
+
+ContentAddressMethod parseContentAddressMethod(std::string_view rawCaMethod);
+
+std::string renderContentAddressMethod(ContentAddressMethod caMethod);
+
 }

src/libstore/daemon.cc

@@ -2,7 +2,6 @@
 #include "monitor-fd.hh"
 #include "worker-protocol.hh"
 #include "store-api.hh"
-#include "local-store.hh"
 #include "finally.hh"
 #include "affinity.hh"
 #include "archive.hh"
@@ -240,6 +239,23 @@ struct ClientSettings
     }
 };
 
+static void writeValidPathInfo(
+    ref<Store> store,
+    unsigned int clientVersion,
+    Sink & to,
+    std::shared_ptr<const ValidPathInfo> info)
+{
+    to << (info->deriver ? store->printStorePath(*info->deriver) : "")
+       << info->narHash.to_string(Base16, false);
+    writeStorePaths(*store, to, info->references);
+    to << info->registrationTime << info->narSize;
+    if (GET_PROTOCOL_MINOR(clientVersion) >= 16) {
+        to << info->ultimate
+           << info->sigs
+           << renderContentAddress(info->ca);
+    }
+}
+
 static void performOp(TunnelLogger * logger, ref<Store> store,
     TrustedFlag trusted, RecursiveFlag recursive, unsigned int clientVersion,
     Source & from, BufferedSink & to, unsigned int op)
@@ -350,6 +366,41 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddToStore: {
+        if (GET_PROTOCOL_MINOR(clientVersion) >= 25) {
+            auto name = readString(from);
+            auto camStr = readString(from);
+            auto refs = readStorePaths<StorePathSet>(*store, from);
+            bool repairBool;
+            from >> repairBool;
+            auto repair = RepairFlag{repairBool};
+
+            logger->startWork();
+            auto pathInfo = [&]() {
+                // NB: FramedSource must be out of scope before logger->stopWork();
+                ContentAddressMethod contentAddressMethod = parseContentAddressMethod(camStr);
+                FramedSource source(from);
+                // TODO this is essentially RemoteStore::addCAToStore. Move it up to Store.
+                return std::visit(overloaded {
+                    [&](TextHashMethod &_) {
+                        // We could stream this by changing Store
+                        std::string contents = source.drain();
+                        auto path = store->addTextToStore(name, contents, refs, repair);
+                        return store->queryPathInfo(path);
+                    },
+                    [&](FixedOutputHashMethod &fohm) {
+                        if (!refs.empty())
+                            throw UnimplementedError("cannot yet have refs with flat or nar-hashed data");
+                        auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair);
+                        return store->queryPathInfo(path);
+                    },
+                }, contentAddressMethod);
+            }();
+            logger->stopWork();
+
+            to << store->printStorePath(pathInfo->path);
+            writeValidPathInfo(store, clientVersion, to, pathInfo);
+
+        } else {
             HashType hashAlgo;
             std::string baseName;
             FileIngestionMethod method;
@@ -391,6 +442,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             logger->stopWork();
 
             to << store->printStorePath(path);
+        }
         break;
     }
 
@@ -494,6 +546,20 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
            are in fact content-addressed if we don't trust them. */
         assert(derivationIsCA(drv.type()) || trusted);
 
+        /* Recompute the derivation path when we cannot trust the original. */
+        if (!trusted) {
+            /* Recomputing the derivation path for input-address derivations
+               makes it harder to audit them after the fact, since we need the
+               original not-necessarily-resolved derivation to verify the drv
+               derivation as adequate claim to the input-addressed output
+               paths. */
+            assert(derivationIsCA(drv.type()));
+
+            Derivation drv2;
+            static_cast<BasicDerivation &>(drv2) = drv;
+            drvPath = writeDerivation(*store, Derivation { drv2 });
+        }
+
         auto res = store->buildDerivation(drvPath, drv, buildMode);
         logger->stopWork();
         to << res.status << res.errorMsg;
@@ -675,15 +741,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         if (info) {
             if (GET_PROTOCOL_MINOR(clientVersion) >= 17)
                 to << 1;
-            to << (info->deriver ? store->printStorePath(*info->deriver) : "")
+            writeValidPathInfo(store, clientVersion, to, info);
-               << info->narHash.to_string(Base16, false);
-            writeStorePaths(*store, to, info->references);
-            to << info->registrationTime << info->narSize;
-            if (GET_PROTOCOL_MINOR(clientVersion) >= 16) {
-                to << info->ultimate
-                   << info->sigs
-                   << renderContentAddress(info->ca);
-            }
         } else {
             assert(GET_PROTOCOL_MINOR(clientVersion) >= 17);
             to << 0;
@@ -749,59 +807,12 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             info.ultimate = false;
 
         if (GET_PROTOCOL_MINOR(clientVersion) >= 23) {
-
-            struct FramedSource : Source
-            {
-                Source & from;
-                bool eof = false;
-                std::vector<unsigned char> pending;
-                size_t pos = 0;
-
-                FramedSource(Source & from) : from(from)
-                { }
-
-                ~FramedSource()
-                {
-                    if (!eof) {
-                        while (true) {
-                            auto n = readInt(from);
-                            if (!n) break;
-                            std::vector<unsigned char> data(n);
-                            from(data.data(), n);
-                        }
-                    }
-                }
-
-                size_t read(unsigned char * data, size_t len) override
-                {
-                    if (eof) throw EndOfFile("reached end of FramedSource");
-
-                    if (pos >= pending.size()) {
-                        size_t len = readInt(from);
-                        if (!len) {
-                            eof = true;
-                            return 0;
-                        }
-                        pending = std::vector<unsigned char>(len);
-                        pos = 0;
-                        from(pending.data(), len);
-                    }
-
-                    auto n = std::min(len, pending.size() - pos);
-                    memcpy(data, pending.data() + pos, n);
-                    pos += n;
-                    return n;
-                }
-            };
-
             logger->startWork();
-
             {
                 FramedSource source(from);
                 store->addToStore(info, source, (RepairFlag) repair,
                     dontCheckSigs ? NoCheckSigs : CheckSigs);
             }
-
             logger->stopWork();
         }
 

src/libstore/derivations.cc

@@ -69,7 +69,7 @@ bool BasicDerivation::isBuiltin() const
 
 
 StorePath writeDerivation(Store & store,
-    const Derivation & drv, RepairFlag repair)
+    const Derivation & drv, RepairFlag repair, bool readOnly)
 {
     auto references = drv.inputSrcs;
     for (auto & i : drv.inputDrvs)
@@ -79,7 +79,7 @@ StorePath writeDerivation(Store & store,
        held during a garbage collection). */
     auto suffix = std::string(drv.name) + drvExtension;
     auto contents = drv.unparse(store, false);
-    return settings.readOnlyMode
+    return readOnly || settings.readOnlyMode
         ? store.computeStorePathForText(suffix, contents, references)
         : store.addTextToStore(suffix, contents, references, repair);
 }
@@ -644,4 +644,57 @@ std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath
     return "/" + hashString(htSHA256, clearText).to_string(Base32, false);
 }
 
+
+// N.B. Outputs are left unchanged
+static void rewriteDerivation(Store & store, BasicDerivation & drv, const StringMap & rewrites) {
+
+    debug("Rewriting the derivation");
+
+    for (auto &rewrite: rewrites) {
+        debug("rewriting %s as %s", rewrite.first, rewrite.second);
+    }
+
+    drv.builder = rewriteStrings(drv.builder, rewrites);
+    for (auto & arg: drv.args) {
+        arg = rewriteStrings(arg, rewrites);
+    }
+
+    StringPairs newEnv;
+    for (auto & envVar: drv.env) {
+        auto envName = rewriteStrings(envVar.first, rewrites);
+        auto envValue = rewriteStrings(envVar.second, rewrites);
+        newEnv.emplace(envName, envValue);
+    }
+    drv.env = newEnv;
+}
+
+
+Sync<DrvPathResolutions> drvPathResolutions;
+
+std::optional<BasicDerivation> Derivation::tryResolve(Store & store) {
+    BasicDerivation resolved { *this };
+
+    // Input paths that we'll want to rewrite in the derivation
+    StringMap inputRewrites;
+
+    for (auto & input : inputDrvs) {
+        auto inputDrvOutputs = store.queryPartialDerivationOutputMap(input.first);
+        StringSet newOutputNames;
+        for (auto & outputName : input.second) {
+            auto actualPathOpt = inputDrvOutputs.at(outputName);
+            if (!actualPathOpt)
+                return std::nullopt;
+            auto actualPath = *actualPathOpt;
+            inputRewrites.emplace(
+                downstreamPlaceholder(store, input.first, outputName),
+                store.printStorePath(actualPath));
+            resolved.inputSrcs.insert(std::move(actualPath));
+        }
+    }
+
+    rewriteDerivation(store, resolved, inputRewrites);
+
+    return resolved;
+}
+
 }

src/libstore/derivations.hh

@@ -4,6 +4,7 @@
 #include "types.hh"
 #include "hash.hh"
 #include "content-address.hh"
+#include "sync.hh"
 
 #include <map>
 #include <variant>
@@ -100,7 +101,7 @@ struct BasicDerivation
     StringPairs env;
     std::string name;
 
-    BasicDerivation() { }
+    BasicDerivation() = default;
     virtual ~BasicDerivation() { };
 
     bool isBuiltin() const;
@@ -127,7 +128,17 @@ struct Derivation : BasicDerivation
     std::string unparse(const Store & store, bool maskOutputs,
         std::map<std::string, StringSet> * actualInputs = nullptr) const;
 
-    Derivation() { }
+    /* Return the underlying basic derivation but with these changes:
+
+	   1. Input drvs are emptied, but the outputs of them that were used are
+	      added directly to input sources.
+
+       2. Input placeholders are replaced with realized input store paths. */
+    std::optional<BasicDerivation> tryResolve(Store & store);
+
+    Derivation() = default;
+    Derivation(const BasicDerivation & bd) : BasicDerivation(bd) { }
+    Derivation(BasicDerivation && bd) : BasicDerivation(std::move(bd)) { }
 };
 
 
@@ -137,7 +148,9 @@ enum RepairFlag : bool { NoRepair = false, Repair = true };
 
 /* Write a derivation to the Nix store, and return its path. */
 StorePath writeDerivation(Store & store,
-    const Derivation & drv, RepairFlag repair = NoRepair);
+    const Derivation & drv,
+    RepairFlag repair = NoRepair,
+    bool readOnly = false);
 
 /* Read a derivation from a file. */
 Derivation parseDerivation(const Store & store, std::string && s, std::string_view name);
@@ -191,6 +204,16 @@ typedef std::map<StorePath, DrvHashModulo> DrvHashes;
 
 extern DrvHashes drvHashes; // FIXME: global, not thread-safe
 
+/* Memoisation of `readDerivation(..).resove()`. */
+typedef std::map<
+    StorePath,
+    std::optional<StorePath>
+> DrvPathResolutions;
+
+// FIXME: global, though at least thread-safe.
+// FIXME: arguably overlaps with hashDerivationModulo memo table.
+extern Sync<DrvPathResolutions> drvPathResolutions;
+
 bool wantOutput(const string & output, const std::set<string> & wanted);
 
 struct Source;

src/libstore/dummy-store.cc

@@ -1,4 +1,5 @@
 #include "store-api.hh"
+#include "callback.hh"
 
 namespace nix {
 

src/libstore/filetransfer.cc

@@ -5,6 +5,7 @@
 #include "s3.hh"
 #include "compression.hh"
 #include "finally.hh"
+#include "callback.hh"
 
 #ifdef ENABLE_S3
 #include <aws/core/client/ClientConfiguration.h>

src/libstore/filetransfer.hh

@@ -66,9 +66,6 @@ struct FileTransferRequest
     FileTransferRequest(const std::string & uri)
         : uri(uri), parentAct(getCurActivity()) { }
 
-    FileTransferRequest(const std::string & uri, Headers headers)
-        : uri(uri), headers(headers) { }
-
     std::string verb()
     {
         return data ? "upload" : "download";

src/libstore/gc.cc

@@ -574,9 +574,12 @@ bool LocalStore::canReachRoot(GCState & state, StorePathSet & visited, const Sto
     /* If keep-derivations is set and this is a derivation, then
        don't delete the derivation if any of the outputs are alive. */
     if (state.gcKeepDerivations && path.isDerivation()) {
-        for (auto & i : queryDerivationOutputs(path))
+        for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(path))
-            if (isValidPath(i) && queryPathInfo(i)->deriver == path)
+            if (maybeOutPath &&
-                incoming.insert(i);
+                isValidPath(*maybeOutPath) &&
+                queryPathInfo(*maybeOutPath)->deriver == path
+                )
+                incoming.insert(*maybeOutPath);
     }
 
     /* If keep-outputs is set, then don't delete this path if there
@@ -660,9 +663,7 @@ void LocalStore::removeUnusedLinks(const GCState & state)
         if (name == "." || name == "..") continue;
         Path path = linksDir + "/" + name;
 
-        struct stat st;
+        auto st = lstat(path);
-        if (lstat(path.c_str(), &st) == -1)
-            throw SysError("statting '%1%'", path);
 
         if (st.st_nlink != 1) {
             actualSize += st.st_size;

src/libstore/globals.cc

@@ -2,6 +2,7 @@
 #include "util.hh"
 #include "archive.hh"
 #include "args.hh"
+#include "abstract-setting-to-json.hh"
 
 #include <algorithm>
 #include <map>
@@ -41,6 +42,7 @@ Settings::Settings()
 {
     buildUsersGroup = getuid() == 0 ? "nixbld" : "";
     lockCPU = getEnv("NIX_AFFINITY_HACK") == "1";
+    allowSymlinkedStore = getEnv("NIX_IGNORE_SYMLINK_STORE") == "1";
 
     caFile = getEnv("NIX_SSL_CERT_FILE").value_or(getEnv("SSL_CERT_FILE").value_or(""));
     if (caFile == "") {
@@ -146,6 +148,12 @@ bool Settings::isWSL1()
 
 const string nixVersion = PACKAGE_VERSION;
 
+NLOHMANN_JSON_SERIALIZE_ENUM(SandboxMode, {
+    {SandboxMode::smEnabled, true},
+    {SandboxMode::smRelaxed, "relaxed"},
+    {SandboxMode::smDisabled, false},
+});
+
 template<> void BaseSetting<SandboxMode>::set(const std::string & str)
 {
     if (str == "true") value = smEnabled;

src/libstore/globals.hh

@@ -2,7 +2,6 @@
 
 #include "types.hh"
 #include "config.hh"
-#include "abstractsettingtojson.hh"
 #include "util.hh"
 
 #include <map>
@@ -930,6 +929,19 @@ public:
 
     Setting<std::string> flakeRegistry{this, "https://github.com/NixOS/flake-registry/raw/master/flake-registry.json", "flake-registry",
         "Path or URI of the global flake registry."};
+
+    Setting<bool> allowSymlinkedStore{
+        this, false, "allow-symlinked-store",
+        R"(
+          If set to `true`, Nix will stop complaining if the store directory
+          (typically /nix/store) contains symlink components.
+
+          This risks making some builds "impure" because builders sometimes
+          "canonicalise" paths by resolving all symlink components. Problems
+          occur if those builds are then deployed to machines where /nix/store
+          resolves to a different location from that of the build machine. You
+          can enable this setting if you are sure you're not going to do that.
+        )"};
 };
 
 

src/libstore/http-binary-cache-store.cc

@@ -2,6 +2,7 @@
 #include "filetransfer.hh"
 #include "globals.hh"
 #include "nar-info-disk-cache.hh"
+#include "callback.hh"
 
 namespace nix {
 

src/libstore/legacy-ssh-store.cc

@@ -6,6 +6,7 @@
 #include "worker-protocol.hh"
 #include "ssh.hh"
 #include "derivations.hh"
+#include "callback.hh"
 
 namespace nix {
 

src/libstore/local-store.cc

@@ -6,6 +6,7 @@
 #include "derivations.hh"
 #include "nar-info.hh"
 #include "references.hh"
+#include "callback.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -109,12 +110,11 @@ LocalStore::LocalStore(const Params & params)
     }
 
     /* Ensure that the store and its parents are not symlinks. */
-    if (getEnv("NIX_IGNORE_SYMLINK_STORE") != "1") {
+    if (!settings.allowSymlinkedStore) {
         Path path = realStoreDir;
         struct stat st;
         while (path != "/") {
-            if (lstat(path.c_str(), &st))
+            st = lstat(path);
-                throw SysError("getting status of '%1%'", path);
             if (S_ISLNK(st.st_mode))
                 throw Error(
                         "the path '%1%' is a symlink; "
@@ -418,10 +418,7 @@ static void canonicaliseTimestampAndPermissions(const Path & path, const struct
 
 void canonicaliseTimestampAndPermissions(const Path & path)
 {
-    struct stat st;
+    canonicaliseTimestampAndPermissions(path, lstat(path));
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
-    canonicaliseTimestampAndPermissions(path, st);
 }
 
 
@@ -439,9 +436,7 @@ static void canonicalisePathMetaData_(const Path & path, uid_t fromUid, InodesSe
     }
 #endif
 
-    struct stat st;
+    auto st = lstat(path);
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
 
     /* Really make sure that the path is of a supported type. */
     if (!(S_ISREG(st.st_mode) || S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode)))
@@ -477,8 +472,7 @@ static void canonicalisePathMetaData_(const Path & path, uid_t fromUid, InodesSe
        ensure that we don't fail on hard links within the same build
        (i.e. "touch $out/foo; ln $out/foo $out/bar"). */
     if (fromUid != (uid_t) -1 && st.st_uid != fromUid) {
-        assert(!S_ISDIR(st.st_mode));
+        if (S_ISDIR(st.st_mode) || !inodesSeen.count(Inode(st.st_dev, st.st_ino)))
-        if (inodesSeen.find(Inode(st.st_dev, st.st_ino)) == inodesSeen.end())
             throw BuildError("invalid ownership on file '%1%'", path);
         mode_t mode = st.st_mode & ~S_IFMT;
         assert(S_ISLNK(st.st_mode) || (st.st_uid == geteuid() && (mode == 0444 || mode == 0555) && st.st_mtime == mtimeStore));
@@ -521,9 +515,7 @@ void canonicalisePathMetaData(const Path & path, uid_t fromUid, InodesSeen & ino
 
     /* On platforms that don't have lchown(), the top-level path can't
        be a symlink, since we can't change its ownership. */
-    struct stat st;
+    auto st = lstat(path);
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
 
     if (st.st_uid != geteuid()) {
         assert(S_ISLNK(st.st_mode));
@@ -729,7 +721,7 @@ uint64_t LocalStore::queryValidPathId(State & state, const StorePath & path)
 {
     auto use(state.stmtQueryPathInfo.use()(printStorePath(path)));
     if (!use.next())
-        throw Error("path '%s' is not valid", printStorePath(path));
+        throw InvalidPath("path '%s' is not valid", printStorePath(path));
     return use.getInt(0);
 }
 
@@ -804,18 +796,58 @@ StorePathSet LocalStore::queryValidDerivers(const StorePath & path)
 }
 
 
-std::map<std::string, std::optional<StorePath>> LocalStore::queryPartialDerivationOutputMap(const StorePath & path)
+std::map<std::string, std::optional<StorePath>> LocalStore::queryPartialDerivationOutputMap(const StorePath & path_)
 {
+    auto path = path_;
     std::map<std::string, std::optional<StorePath>> outputs;
-    BasicDerivation drv = readDerivation(path);
+    Derivation drv = readDerivation(path);
     for (auto & [outName, _] : drv.outputs) {
         outputs.insert_or_assign(outName, std::nullopt);
     }
+    bool haveCached = false;
+    {
+        auto resolutions = drvPathResolutions.lock();
+        auto resolvedPathOptIter = resolutions->find(path);
+        if (resolvedPathOptIter != resolutions->end()) {
+            auto & [_, resolvedPathOpt] = *resolvedPathOptIter;
+            if (resolvedPathOpt)
+                path = *resolvedPathOpt;
+            haveCached = true;
+        }
+    }
+    /* can't just use else-if instead of `!haveCached` because we need to unlock
+       `drvPathResolutions` before it is locked in `Derivation::resolve`. */
+    if (!haveCached && drv.type() == DerivationType::CAFloating) {
+        /* Try resolve drv and use that path instead. */
+        auto attempt = drv.tryResolve(*this);
+        if (!attempt)
+            /* If we cannot resolve the derivation, we cannot have any path
+               assigned so we return the map of all std::nullopts. */
+            return outputs;
+        /* Just compute store path */
+        auto pathResolved = writeDerivation(*this, *std::move(attempt), NoRepair, true);
+        /* Store in memo table. */
+        /* FIXME: memo logic should not be local-store specific, should have
+           wrapper-method instead. */
+        drvPathResolutions.lock()->insert_or_assign(path, pathResolved);
+        path = std::move(pathResolved);
+    }
     return retrySQLite<std::map<std::string, std::optional<StorePath>>>([&]() {
         auto state(_state.lock());
 
-        auto useQueryDerivationOutputs(state->stmtQueryDerivationOutputs.use()
+        uint64_t drvId;
-            (queryValidPathId(*state, path)));
+        try {
+            drvId = queryValidPathId(*state, path);
+        } catch (InvalidPath &) {
+            /* FIXME? if the derivation doesn't exist, we cannot have a mapping
+               for it. */
+            return outputs;
+        }
+
+        auto useQueryDerivationOutputs {
+            state->stmtQueryDerivationOutputs.use()
+            (drvId)
+        };
 
         while (useQueryDerivationOutputs.next())
             outputs.insert_or_assign(
@@ -1454,7 +1486,7 @@ static void makeMutable(const Path & path)
 {
     checkInterrupt();
 
-    struct stat st = lstat(path);
+    auto st = lstat(path);
 
     if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode)) return;
 

src/libstore/misc.cc

@@ -5,7 +5,7 @@
 #include "store-api.hh"
 #include "thread-pool.hh"
 #include "topo-sort.hh"
-
+#include "callback.hh"
 
 namespace nix {
 

src/libstore/names.cc

@@ -1,10 +1,18 @@
 #include "names.hh"
 #include "util.hh"
 
+#include <regex>
+
 
 namespace nix {
 
 
+struct Regex
+{
+    std::regex regex;
+};
+
+
 DrvName::DrvName()
 {
     name = "";
@@ -30,11 +38,18 @@ DrvName::DrvName(std::string_view s) : hits(0)
 }
 
 
+DrvName::~DrvName()
+{ }
+
+
 bool DrvName::matches(DrvName & n)
 {
     if (name != "*") {
-        if (!regex) regex = std::unique_ptr<std::regex>(new std::regex(name, std::regex::extended));
+        if (!regex) {
-        if (!std::regex_match(n.name, *regex)) return false;
+            regex = std::make_unique<Regex>();
+            regex->regex = std::regex(name, std::regex::extended);
+        }
+        if (!std::regex_match(n.name, regex->regex)) return false;
     }
     if (version != "" && version != n.version) return false;
     return true;
@@ -99,7 +114,7 @@ DrvNames drvNamesFromArgs(const Strings & opArgs)
 {
     DrvNames result;
     for (auto & i : opArgs)
-        result.push_back(DrvName(i));
+        result.emplace_back(i);
     return result;
 }
 

src/libstore/names.hh

@@ -3,10 +3,11 @@
 #include <memory>
 
 #include "types.hh"
-#include <regex>
 
 namespace nix {
 
+struct Regex;
+
 struct DrvName
 {
     string fullName;
@@ -16,10 +17,12 @@ struct DrvName
 
     DrvName();
     DrvName(std::string_view s);
+    ~DrvName();
+
     bool matches(DrvName & n);
 
 private:
-    std::unique_ptr<std::regex> regex;
+    std::unique_ptr<Regex> regex;
 };
 
 typedef list<DrvName> DrvNames;

src/libstore/optimise-store.cc

@@ -17,9 +17,7 @@ namespace nix {
 
 static void makeWritable(const Path & path)
 {
-    struct stat st;
+    auto st = lstat(path);
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
     if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
         throw SysError("changing writability of '%1%'", path);
 }
@@ -94,9 +92,7 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
 {
     checkInterrupt();
 
-    struct stat st;
+    auto st = lstat(path);
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
 
 #if __APPLE__
     /* HFS/macOS has some undocumented security feature disabling hardlinking for
@@ -187,9 +183,7 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
 
     /* Yes!  We've seen a file with the same contents.  Replace the
        current file with a hard link to that file. */
-    struct stat stLink;
+    auto stLink = lstat(linkPath);
-    if (lstat(linkPath.c_str(), &stLink))
-        throw SysError("getting attributes of path '%1%'", linkPath);
 
     if (st.st_ino == stLink.st_ino) {
         debug(format("'%1%' is already linked to '%2%'") % path % linkPath);

src/libstore/profiles.cc

@@ -39,13 +39,10 @@ std::pair<Generations, std::optional<GenerationNumber>> findGenerations(Path pro
     for (auto & i : readDirectory(profileDir)) {
         if (auto n = parseName(profileName, i.name)) {
             auto path = profileDir + "/" + i.name;
-            struct stat st;
-            if (lstat(path.c_str(), &st) != 0)
-                throw SysError("statting '%1%'", path);
             gens.push_back({
                 .number = *n,
                 .path = path,
-                .creationTime = st.st_mtime
+                .creationTime = lstat(path).st_mtime
             });
         }
     }

src/libstore/remote-store.cc

@@ -10,6 +10,7 @@
 #include "pool.hh"
 #include "finally.hh"
 #include "logging.hh"
+#include "callback.hh"
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -97,7 +98,16 @@ RemoteStore::RemoteStore(const Params & params)
     , RemoteStoreConfig(params)
     , connections(make_ref<Pool<Connection>>(
             std::max(1, (int) maxConnections),
-            [this]() { return openConnectionWrapper(); },
+            [this]() {
+                auto conn = openConnectionWrapper();
+                try {
+                    initConnection(*conn);
+                } catch (...) {
+                    failed = true;
+                    throw;
+                }
+                return conn;
+            },
             [this](const ref<Connection> & r) {
                 return
                     r->to.good()
@@ -182,8 +192,6 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
 
     conn->startTime = std::chrono::steady_clock::now();
 
-    initConnection(*conn);
-
     return conn;
 }
 
@@ -299,6 +307,8 @@ struct ConnectionHandle
             std::rethrow_exception(ex);
         }
     }
+
+    void withFramedSink(std::function<void(Sink & sink)> fun);
 };
 
 
@@ -412,11 +422,28 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
 }
 
 
+ref<const ValidPathInfo> RemoteStore::readValidPathInfo(ConnectionHandle & conn, const StorePath & path)
+{
+    auto deriver = readString(conn->from);
+    auto narHash = Hash::parseAny(readString(conn->from), htSHA256);
+    auto info = make_ref<ValidPathInfo>(path, narHash);
+    if (deriver != "") info->deriver = parseStorePath(deriver);
+    info->references = readStorePaths<StorePathSet>(*this, conn->from);
+    conn->from >> info->registrationTime >> info->narSize;
+    if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 16) {
+        conn->from >> info->ultimate;
+        info->sigs = readStrings<StringSet>(conn->from);
+        info->ca = parseContentAddressOpt(readString(conn->from));
+    }
+    return info;
+}
+
+
 void RemoteStore::queryPathInfoUncached(const StorePath & path,
     Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept
 {
     try {
-        std::shared_ptr<ValidPathInfo> info;
+        std::shared_ptr<const ValidPathInfo> info;
         {
             auto conn(getConnection());
             conn->to << wopQueryPathInfo << printStorePath(path);
@@ -432,17 +459,7 @@ void RemoteStore::queryPathInfoUncached(const StorePath & path,
                 bool valid; conn->from >> valid;
                 if (!valid) throw InvalidPath("path '%s' is not valid", printStorePath(path));
             }
-            auto deriver = readString(conn->from);
+            info = readValidPathInfo(conn, path);
-            auto narHash = Hash::parseAny(readString(conn->from), htSHA256);
-            info = std::make_shared<ValidPathInfo>(path, narHash);
-            if (deriver != "") info->deriver = parseStorePath(deriver);
-            info->references = readStorePaths<StorePathSet>(*this, conn->from);
-            conn->from >> info->registrationTime >> info->narSize;
-            if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 16) {
-                conn->from >> info->ultimate;
-                info->sigs = readStrings<StringSet>(conn->from);
-                info->ca = parseContentAddressOpt(readString(conn->from));
-            }
         }
         callback(std::move(info));
     } catch (...) { callback.rethrow(); }
@@ -517,6 +534,93 @@ std::optional<StorePath> RemoteStore::queryPathFromHashPart(const std::string &
 }
 
 
+ref<const ValidPathInfo> RemoteStore::addCAToStore(
+    Source & dump,
+    const string & name,
+    ContentAddressMethod caMethod,
+    const StorePathSet & references,
+    RepairFlag repair)
+{
+    std::optional<ConnectionHandle> conn_(getConnection());
+    auto & conn = *conn_;
+
+    if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 25) {
+
+        conn->to
+            << wopAddToStore
+            << name
+            << renderContentAddressMethod(caMethod);
+        writeStorePaths(*this, conn->to, references);
+        conn->to << repair;
+
+        conn.withFramedSink([&](Sink & sink) {
+            dump.drainInto(sink);
+        });
+
+        auto path = parseStorePath(readString(conn->from));
+        return readValidPathInfo(conn, path);
+    }
+    else {
+        if (repair) throw Error("repairing is not supported when building through the Nix daemon protocol < 1.25");
+
+        std::visit(overloaded {
+            [&](TextHashMethod thm) -> void {
+                std::string s = dump.drain();
+                conn->to << wopAddTextToStore << name << s;
+                writeStorePaths(*this, conn->to, references);
+                conn.processStderr();
+            },
+            [&](FixedOutputHashMethod fohm) -> void {
+                conn->to
+                    << wopAddToStore
+                    << name
+                    << ((fohm.hashType == htSHA256 && fohm.fileIngestionMethod == FileIngestionMethod::Recursive) ? 0 : 1) /* backwards compatibility hack */
+                    << (fohm.fileIngestionMethod == FileIngestionMethod::Recursive ? 1 : 0)
+                    << printHashType(fohm.hashType);
+
+                try {
+                    conn->to.written = 0;
+                    conn->to.warn = true;
+                    connections->incCapacity();
+                    {
+                        Finally cleanup([&]() { connections->decCapacity(); });
+                        if (fohm.fileIngestionMethod == FileIngestionMethod::Recursive) {
+                            dump.drainInto(conn->to);
+                        } else {
+                            std::string contents = dump.drain();
+                            dumpString(contents, conn->to);
+                        }
+                    }
+                    conn->to.warn = false;
+                    conn.processStderr();
+                } catch (SysError & e) {
+                    /* Daemon closed while we were sending the path. Probably OOM
+                      or I/O error. */
+                    if (e.errNo == EPIPE)
+                        try {
+                            conn.processStderr();
+                        } catch (EndOfFile & e) { }
+                    throw;
+                }
+
+            }
+        }, caMethod);
+        auto path = parseStorePath(readString(conn->from));
+        // Release our connection to prevent a deadlock in queryPathInfo().
+        conn_.reset();
+        return queryPathInfo(path);
+    }
+}
+
+
+StorePath RemoteStore::addToStoreFromDump(Source & dump, const string & name,
+        FileIngestionMethod method, HashType hashType, RepairFlag repair)
+{
+    StorePathSet references;
+    return addCAToStore(dump, name, FixedOutputHashMethod{ .fileIngestionMethod = method, .hashType = hashType }, references, repair)->path;
+}
+
+
 void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
     RepairFlag repair, CheckSigsFlag checkSigs)
 {
@@ -557,78 +661,9 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
                  << repair << !checkSigs;
 
         if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 23) {
-
+            conn.withFramedSink([&](Sink & sink) {
-            conn->to.flush();
-
-            std::exception_ptr ex;
-
-            struct FramedSink : BufferedSink
-            {
-                ConnectionHandle & conn;
-                std::exception_ptr & ex;
-
-                FramedSink(ConnectionHandle & conn, std::exception_ptr & ex) : conn(conn), ex(ex)
-                { }
-
-                ~FramedSink()
-                {
-                    try {
-                        conn->to << 0;
-                        conn->to.flush();
-                    } catch (...) {
-                        ignoreException();
-                    }
-                }
-
-                void write(const unsigned char * data, size_t len) override
-                {
-                    /* Don't send more data if the remote has
-                       encountered an error. */
-                    if (ex) {
-                        auto ex2 = ex;
-                        ex = nullptr;
-                        std::rethrow_exception(ex2);
-                    }
-                    conn->to << len;
-                    conn->to(data, len);
-                };
-            };
-
-            /* Handle log messages / exceptions from the remote on a
-               separate thread. */
-            std::thread stderrThread([&]()
-            {
-                try {
-                    conn.processStderr(nullptr, nullptr, false);
-                } catch (...) {
-                    ex = std::current_exception();
-                }
-            });
-
-            Finally joinStderrThread([&]()
-            {
-                if (stderrThread.joinable()) {
-                    stderrThread.join();
-                    if (ex) {
-                        try {
-                            std::rethrow_exception(ex);
-                        } catch (...) {
-                            ignoreException();
-                        }
-                    }
-                }
-            });
-
-            {
-                FramedSink sink(conn, ex);
                 copyNAR(source, sink);
-                sink.flush();
+            });
-            }
-
-            stderrThread.join();
-            if (ex)
-                std::rethrow_exception(ex);
-
         } else if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 21) {
             conn.processStderr(0, &source);
         } else {
@@ -639,57 +674,11 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
 }
 
 
-StorePath RemoteStore::addToStore(const string & name, const Path & _srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
-{
-    if (repair) throw Error("repairing is not supported when building through the Nix daemon");
-
-    auto conn(getConnection());
-
-    Path srcPath(absPath(_srcPath));
-
-    conn->to
-        << wopAddToStore
-        << name
-        << ((hashAlgo == htSHA256 && method == FileIngestionMethod::Recursive) ? 0 : 1) /* backwards compatibility hack */
-        << (method == FileIngestionMethod::Recursive ? 1 : 0)
-        << printHashType(hashAlgo);
-
-    try {
-        conn->to.written = 0;
-        conn->to.warn = true;
-        connections->incCapacity();
-        {
-            Finally cleanup([&]() { connections->decCapacity(); });
-            dumpPath(srcPath, conn->to, filter);
-        }
-        conn->to.warn = false;
-        conn.processStderr();
-    } catch (SysError & e) {
-        /* Daemon closed while we were sending the path. Probably OOM
-           or I/O error. */
-        if (e.errNo == EPIPE)
-            try {
-                conn.processStderr();
-            } catch (EndOfFile & e) { }
-        throw;
-    }
-
-    return parseStorePath(readString(conn->from));
-}
-
-
 StorePath RemoteStore::addTextToStore(const string & name, const string & s,
     const StorePathSet & references, RepairFlag repair)
 {
-    if (repair) throw Error("repairing is not supported when building through the Nix daemon");
+    StringSource source(s);
-
+    return addCAToStore(source, name, TextHashMethod{}, references, repair)->path;
-    auto conn(getConnection());
-    conn->to << wopAddTextToStore << name << s;
-    writeStorePaths(*this, conn->to, references);
-
-    conn.processStderr();
-    return parseStorePath(readString(conn->from));
 }
 
 
@@ -985,6 +974,49 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink * sink, Source *
     return nullptr;
 }
 
+void ConnectionHandle::withFramedSink(std::function<void(Sink &sink)> fun)
+{
+    (*this)->to.flush();
+
+    std::exception_ptr ex;
+
+    /* Handle log messages / exceptions from the remote on a
+        separate thread. */
+    std::thread stderrThread([&]()
+    {
+        try {
+            processStderr(nullptr, nullptr, false);
+        } catch (...) {
+            ex = std::current_exception();
+        }
+    });
+
+    Finally joinStderrThread([&]()
+    {
+        if (stderrThread.joinable()) {
+            stderrThread.join();
+            if (ex) {
+                try {
+                    std::rethrow_exception(ex);
+                } catch (...) {
+                    ignoreException();
+                }
+            }
+        }
+    });
+
+    {
+        FramedSink sink((*this)->to, ex);
+        fun(sink);
+        sink.flush();
+    }
+
+    stderrThread.join();
+    if (ex)
+        std::rethrow_exception(ex);
+
+}
+
 static RegisterStoreImplementation<UDSRemoteStore, UDSRemoteStoreConfig> regStore;
 
 }

src/libstore/remote-store.hh

@@ -63,13 +63,21 @@ public:
     void querySubstitutablePathInfos(const StorePathCAMap & paths,
         SubstitutablePathInfos & infos) override;
 
+    /* Add a content-addressable store path. `dump` will be drained. */
+    ref<const ValidPathInfo> addCAToStore(
+        Source & dump,
+        const string & name,
+        ContentAddressMethod caMethod,
+        const StorePathSet & references,
+        RepairFlag repair);
+
+    /* Add a content-addressable store path. Does not support references. `dump` will be drained. */
+    StorePath addToStoreFromDump(Source & dump, const string & name,
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override;
+
     void addToStore(const ValidPathInfo & info, Source & nar,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
-    StorePath addToStore(const string & name, const Path & srcPath,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override;
-
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
 
@@ -106,8 +114,6 @@ public:
 
     void flushBadConnections();
 
-protected:
-
     struct Connection
     {
         AutoCloseFD fd;
@@ -123,6 +129,8 @@ protected:
 
     ref<Connection> openConnectionWrapper();
 
+protected:
+
     virtual ref<Connection> openConnection() = 0;
 
     void initConnection(Connection & conn);
@@ -139,6 +147,8 @@ protected:
 
     virtual void narFromPath(const StorePath & path, Sink & sink) override;
 
+    ref<const ValidPathInfo> readValidPathInfo(ConnectionHandle & conn, const StorePath & path);
+
 private:
 
     std::atomic_bool failed{false};

src/libstore/ssh-store.cc

@@ -80,7 +80,6 @@ ref<RemoteStore::Connection> SSHStore::openConnection()
         + (remoteStore.get() == "" ? "" : " --store " + shellEscape(remoteStore.get())));
     conn->to = FdSink(conn->sshConn->in.get());
     conn->from = FdSource(conn->sshConn->out.get());
-    initConnection(*conn);
     return conn;
 }
 

src/libstore/store-api.cc

@@ -8,9 +8,7 @@
 #include "json.hh"
 #include "url.hh"
 #include "archive.hh"
-
+#include "callback.hh"
-#include <future>
-
 
 namespace nix {
 
@@ -1040,37 +1038,25 @@ static bool isNonUriPath(const std::string & spec) {
         && spec.find("/") != std::string::npos;
 }
 
-StoreType getStoreType(const std::string & uri, const std::string & stateDir)
-{
-    if (uri == "daemon") {
-        return tDaemon;
-    } else if (uri == "local" || isNonUriPath(uri)) {
-        return tLocal;
-    } else if (uri == "" || uri == "auto") {
-        if (access(stateDir.c_str(), R_OK | W_OK) == 0)
-            return tLocal;
-        else if (pathExists(settings.nixDaemonSocketFile))
-            return tDaemon;
-        else
-            return tLocal;
-    } else {
-        return tOther;
-    }
-}
-
 std::shared_ptr<Store> openFromNonUri(const std::string & uri, const Store::Params & params)
 {
-    switch (getStoreType(uri, get(params, "state").value_or(settings.nixStateDir))) {
+    if (uri == "" || uri == "auto") {
-        case tDaemon:
+        auto stateDir = get(params, "state").value_or(settings.nixStateDir);
-            return std::shared_ptr<Store>(std::make_shared<UDSRemoteStore>(params));
+        if (access(stateDir.c_str(), R_OK | W_OK) == 0)
-        case tLocal: {
+            return std::make_shared<LocalStore>(params);
+        else if (pathExists(settings.nixDaemonSocketFile))
+            return std::make_shared<UDSRemoteStore>(params);
+        else
+            return std::make_shared<LocalStore>(params);
+    } else if (uri == "daemon") {
+        return std::make_shared<UDSRemoteStore>(params);
+    } else if (uri == "local") {
+        return std::make_shared<LocalStore>(params);
+    } else if (isNonUriPath(uri)) {
         Store::Params params2 = params;
-            if (isNonUriPath(uri)) {
         params2["root"] = absPath(uri);
-            }
+        return std::make_shared<LocalStore>(params2);
-            return std::shared_ptr<Store>(std::make_shared<LocalStore>(params2));
+    } else {
-        }
-        default:
         return nullptr;
     }
 }

src/libstore/store-api.hh

@@ -449,7 +449,8 @@ public:
     /* 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). */
+       false).
+       `dump` may be drained */
     // FIXME: remove?
     virtual StorePath addToStoreFromDump(Source & dump, const string & name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair)
@@ -478,8 +479,38 @@ public:
         BuildMode buildMode = bmNormal);
 
     /* Build a single non-materialized derivation (i.e. not from an
-       on-disk .drv file). Note that ‘drvPath’ is only used for
+       on-disk .drv file).
-       informational purposes. */
+
+       ‘drvPath’ is used to deduplicate worker goals so it is imperative that
+       is correct. That said, it doesn't literally need to be store path that
+       would be calculated from writing this derivation to the store: it is OK
+       if it instead is that of a Derivation which would resolve to this (by
+       taking the outputs of it's input derivations and adding them as input
+       sources) such that the build time referenceable-paths are the same.
+
+       In the input-addressed case, we usually *do* use an "original"
+       unresolved derivations's path, as that is what will be used in the
+       `buildPaths` case. Also, the input-addressed output paths are verified
+       only by that contents of that specific unresolved derivation, so it is
+       nice to keep that information around so if the original derivation is
+       ever obtained later, it can be verified whether the trusted user in fact
+       used the proper output path.
+
+       In the content-addressed case, we want to always use the
+       resolved drv path calculated from the provided derivation. This serves
+       two purposes:
+
+         - It keeps the operation trustless, by ruling out a maliciously
+           invalid drv path corresponding to a non-resolution-equivalent
+           derivation.
+
+         - For the floating case in particular, it ensures that the derivation
+           to output mapping respects the resolution equivalence relation, so
+           one cannot choose different resolution-equivalent derivations to
+           subvert dependency coherence (i.e. the property that one doesn't end
+           up with multiple different versions of dependencies without
+           explicitly choosing to allow it).
+    */
     virtual BuildResult buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
         BuildMode buildMode = bmNormal) = 0;
 
@@ -516,7 +547,7 @@ public:
        - The collector isn't running, or it's just started but hasn't
          acquired the GC lock yet.  In that case we get and release
          the lock right away, then exit.  The collector scans the
-         permanent root and sees our's.
+         permanent root and sees ours.
 
        In either case the permanent root is seen by the collector. */
     virtual void syncWithGC() { };
@@ -791,16 +822,6 @@ ref<Store> openStore(const std::string & uri = settings.storeUri.get(),
     const Store::Params & extraParams = Store::Params());
 
 
-enum StoreType {
-    tDaemon,
-    tLocal,
-    tOther
-};
-
-
-StoreType getStoreType(const std::string & uri = settings.storeUri.get(),
-    const std::string & stateDir = settings.nixStateDir);
-
 /* Return the default substituter stores, defined by the
    ‘substituters’ option and various legacy options. */
 std::list<ref<Store>> getDefaultSubstituters();

src/libstore/worker-protocol.hh

@@ -6,7 +6,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x118
+#define PROTOCOL_VERSION 0x119
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
@@ -18,7 +18,7 @@ typedef enum {
     wopQueryReferences = 5, // obsolete
     wopQueryReferrers = 6,
     wopAddToStore = 7,
-    wopAddTextToStore = 8,
+    wopAddTextToStore = 8, // obsolete since 1.25, Nix 3.0. Use wopAddToStore
     wopBuildPaths = 9,
     wopEnsurePath = 10,
     wopAddTempRoot = 11,

src/libutil/archive.cc

@@ -27,6 +27,8 @@ struct ArchiveSettings : Config
         #endif
         "use-case-hack",
         "Whether to enable a Darwin-specific hack for dealing with file name collisions."};
+    Setting<bool> preallocateContents{this, true, "preallocate-contents",
+        "Whether to preallocate files when writing objects with known size."};
 };
 
 static ArchiveSettings archiveSettings;
@@ -66,9 +68,7 @@ static void dump(const Path & path, Sink & sink, PathFilter & filter)
 {
     checkInterrupt();
 
-    struct stat st;
+    auto st = lstat(path);
-    if (lstat(path.c_str(), &st))
-        throw SysError("getting attributes of path '%1%'", path);
 
     sink << "(";
 
@@ -325,6 +325,9 @@ struct RestoreSink : ParseSink
 
     void preallocateContents(uint64_t len)
     {
+        if (!archiveSettings.preallocateContents)
+            return;
+
 #if HAVE_POSIX_FALLOCATE
         if (len) {
             errno = posix_fallocate(fd.get(), 0, len);

src/libutil/args.hh

@@ -192,7 +192,7 @@ public:
     {
         expectArgs({
             .label = label,
-            .optional = true,
+            .optional = optional,
             .handler = {dest}
         });
     }

src/libutil/callback.hh

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <future>
+#include <functional>
+
+namespace nix {
+
+/* A callback is a wrapper around a lambda that accepts a valid of
+   type T or an exception. (We abuse std::future<T> to pass the value or
+   exception.) */
+template<typename T>
+class Callback
+{
+    std::function<void(std::future<T>)> fun;
+    std::atomic_flag done = ATOMIC_FLAG_INIT;
+
+public:
+
+    Callback(std::function<void(std::future<T>)> fun) : fun(fun) { }
+
+    Callback(Callback && callback) : fun(std::move(callback.fun))
+    {
+        auto prev = callback.done.test_and_set();
+        if (prev) done.test_and_set();
+    }
+
+    void operator()(T && t) noexcept
+    {
+        auto prev = done.test_and_set();
+        assert(!prev);
+        std::promise<T> promise;
+        promise.set_value(std::move(t));
+        fun(promise.get_future());
+    }
+
+    void rethrow(const std::exception_ptr & exc = std::current_exception()) noexcept
+    {
+        auto prev = done.test_and_set();
+        assert(!prev);
+        std::promise<T> promise;
+        promise.set_exception(exc);
+        fun(promise.get_future());
+    }
+};
+
+}

src/libutil/config.cc

@@ -1,6 +1,6 @@
 #include "config.hh"
 #include "args.hh"
-#include "abstractsettingtojson.hh"
+#include "abstract-setting-to-json.hh"
 
 #include <nlohmann/json.hpp>
 

src/libutil/fmt.hh

@@ -1,7 +1,6 @@
 #pragma once
 
 #include <boost/format.hpp>
-#include <boost/algorithm/string/replace.hpp>
 #include <string>
 #include "ansicolor.hh"
 

src/libutil/serialise.cc

@@ -93,7 +93,7 @@ void Source::operator () (unsigned char * data, size_t len)
 }
 
 
-std::string Source::drain()
+void Source::drainInto(Sink & sink)
 {
     std::string s;
     std::vector<unsigned char> buf(8192);
@@ -101,12 +101,19 @@ std::string Source::drain()
         size_t n;
         try {
             n = read(buf.data(), buf.size());
-            s.append((char *) buf.data(), n);
+            sink(buf.data(), n);
         } catch (EndOfFile &) {
             break;
         }
     }
-    return s;
+}
+
+
+std::string Source::drain()
+{
+    StringSink s;
+    drainInto(s);
+    return *s.s;
 }
 
 

src/libutil/serialise.hh

@@ -69,6 +69,8 @@ struct Source
 
     virtual bool good() { return true; }
 
+    void drainInto(Sink & sink);
+
     std::string drain();
 };
 
@@ -340,7 +342,7 @@ T readNum(Source & source)
         ((uint64_t) buf[6] << 48) |
         ((uint64_t) buf[7] << 56);
 
-    if (n > std::numeric_limits<T>::max())
+    if (n > (uint64_t)std::numeric_limits<T>::max())
         throw SerialisationError("serialised integer %d is too large for type '%s'", n, typeid(T).name());
 
     return (T) n;
@@ -404,4 +406,93 @@ struct StreamToSourceAdapter : Source
 };
 
 
+/* A source that reads a distinct format of concatenated chunks back into its
+   logical form, in order to guarantee a known state to the original stream,
+   even in the event of errors.
+
+   Use with FramedSink, which also allows the logical stream to be terminated
+   in the event of an exception.
+*/
+struct FramedSource : Source
+{
+    Source & from;
+    bool eof = false;
+    std::vector<unsigned char> pending;
+    size_t pos = 0;
+
+    FramedSource(Source & from) : from(from)
+    { }
+
+    ~FramedSource()
+    {
+        if (!eof) {
+            while (true) {
+                auto n = readInt(from);
+                if (!n) break;
+                std::vector<unsigned char> data(n);
+                from(data.data(), n);
+            }
+        }
+    }
+
+    size_t read(unsigned char * data, size_t len) override
+    {
+        if (eof) throw EndOfFile("reached end of FramedSource");
+
+        if (pos >= pending.size()) {
+            size_t len = readInt(from);
+            if (!len) {
+                eof = true;
+                return 0;
+            }
+            pending = std::vector<unsigned char>(len);
+            pos = 0;
+            from(pending.data(), len);
+        }
+
+        auto n = std::min(len, pending.size() - pos);
+        memcpy(data, pending.data() + pos, n);
+        pos += n;
+        return n;
+    }
+};
+
+/* Write as chunks in the format expected by FramedSource.
+
+   The exception_ptr reference can be used to terminate the stream when you
+   detect that an error has occurred on the remote end.
+*/
+struct FramedSink : nix::BufferedSink
+{
+    BufferedSink & to;
+    std::exception_ptr & ex;
+
+    FramedSink(BufferedSink & to, std::exception_ptr & ex) : to(to), ex(ex)
+    { }
+
+    ~FramedSink()
+    {
+        try {
+            to << 0;
+            to.flush();
+        } catch (...) {
+            ignoreException();
+        }
+    }
+
+    void write(const unsigned char * data, size_t len) override
+    {
+        /* Don't send more data if the remote has
+            encountered an error. */
+        if (ex) {
+            auto ex2 = ex;
+            ex = nullptr;
+            std::rethrow_exception(ex2);
+        }
+        to << len;
+        to(data, len);
+    };
+};
+
+
 }

src/libutil/split.hh

@@ -9,7 +9,7 @@ namespace nix {
 
 // If `separator` is found, we return the portion of the string before the
 // separator, and modify the string argument to contain only the part after the
-// separator. Otherwise, wer return `std::nullopt`, and we leave the argument
+// separator. Otherwise, we return `std::nullopt`, and we leave the argument
 // string alone.
 static inline std::optional<std::string_view> splitPrefixTo(std::string_view & string, char separator) {
     auto sepInstance = string.find(separator);

src/libutil/url-parts.hh

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <string>
+#include <regex>
+
+namespace nix {
+
+// URI stuff.
+const static std::string pctEncoded = "(?:%[0-9a-fA-F][0-9a-fA-F])";
+const static std::string schemeRegex = "(?:[a-z+.-]+)";
+const static std::string ipv6AddressRegex = "(?:\\[[0-9a-fA-F:]+\\])";
+const static std::string unreservedRegex = "(?:[a-zA-Z0-9-._~])";
+const static std::string subdelimsRegex = "(?:[!$&'\"()*+,;=])";
+const static std::string hostnameRegex = "(?:(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + ")*)";
+const static std::string hostRegex = "(?:" + ipv6AddressRegex + "|" + hostnameRegex + ")";
+const static std::string userRegex = "(?:(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + "|:)*)";
+const static std::string authorityRegex = "(?:" + userRegex + "@)?" + hostRegex + "(?::[0-9]+)?";
+const static std::string pcharRegex = "(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + "|[:@])";
+const static std::string queryRegex = "(?:" + pcharRegex + "|[/? \"])*";
+const static std::string segmentRegex = "(?:" + pcharRegex + "+)";
+const static std::string absPathRegex = "(?:(?:/" + segmentRegex + ")*/?)";
+const static std::string pathRegex = "(?:" + segmentRegex + "(?:/" + segmentRegex + ")*/?)";
+
+// A Git ref (i.e. branch or tag name).
+const static std::string refRegexS = "[a-zA-Z0-9][a-zA-Z0-9_.-]*"; // FIXME: check
+extern std::regex refRegex;
+
+// Instead of defining what a good Git Ref is, we define what a bad Git Ref is
+// This is because of the definition of a ref in refs.c in https://github.com/git/git
+// See tests/fetchGitRefs.sh for the full definition
+const static std::string badGitRefRegexS = "//|^[./]|/\\.|\\.\\.|[[:cntrl:][:space:]:?^~\[]|\\\\|\\*|\\.lock$|\\.lock/|@\\{|[/.]$|^@$|^$";
+extern std::regex badGitRefRegex;
+
+// A Git revision (a SHA-1 commit hash).
+const static std::string revRegexS = "[0-9a-fA-F]{40}";
+extern std::regex revRegex;
+
+// A ref or revision, or a ref followed by a revision.
+const static std::string refAndOrRevRegex = "(?:(" + revRegexS + ")|(?:(" + refRegexS + ")(?:/(" + revRegexS + "))?))";
+
+const static std::string flakeIdRegexS = "[a-zA-Z][a-zA-Z0-9_-]*";
+extern std::regex flakeIdRegex;
+
+}

src/libutil/url.cc

@@ -1,4 +1,5 @@
 #include "url.hh"
+#include "url-parts.hh"
 #include "util.hh"
 
 namespace nix {

src/libutil/url.hh

@@ -2,8 +2,6 @@
 
 #include "error.hh"
 
-#include <regex>
-
 namespace nix {
 
 struct ParsedURL
@@ -29,40 +27,4 @@ std::map<std::string, std::string> decodeQuery(const std::string & query);
 
 ParsedURL parseURL(const std::string & url);
 
-// URI stuff.
-const static std::string pctEncoded = "(?:%[0-9a-fA-F][0-9a-fA-F])";
-const static std::string schemeRegex = "(?:[a-z+.-]+)";
-const static std::string ipv6AddressRegex = "(?:\\[[0-9a-fA-F:]+\\])";
-const static std::string unreservedRegex = "(?:[a-zA-Z0-9-._~])";
-const static std::string subdelimsRegex = "(?:[!$&'\"()*+,;=])";
-const static std::string hostnameRegex = "(?:(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + ")*)";
-const static std::string hostRegex = "(?:" + ipv6AddressRegex + "|" + hostnameRegex + ")";
-const static std::string userRegex = "(?:(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + "|:)*)";
-const static std::string authorityRegex = "(?:" + userRegex + "@)?" + hostRegex + "(?::[0-9]+)?";
-const static std::string pcharRegex = "(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + "|[:@])";
-const static std::string queryRegex = "(?:" + pcharRegex + "|[/? \"])*";
-const static std::string segmentRegex = "(?:" + pcharRegex + "+)";
-const static std::string absPathRegex = "(?:(?:/" + segmentRegex + ")*/?)";
-const static std::string pathRegex = "(?:" + segmentRegex + "(?:/" + segmentRegex + ")*/?)";
-
-// A Git ref (i.e. branch or tag name).
-const static std::string refRegexS = "[a-zA-Z0-9][a-zA-Z0-9_.-]*"; // FIXME: check
-extern std::regex refRegex;
-
-// Instead of defining what a good Git Ref is, we define what a bad Git Ref is
-// This is because of the definition of a ref in refs.c in https://github.com/git/git
-// See tests/fetchGitRefs.sh for the full definition
-const static std::string badGitRefRegexS = "//|^[./]|/\\.|\\.\\.|[[:cntrl:][:space:]:?^~\[]|\\\\|\\*|\\.lock$|\\.lock/|@\\{|[/.]$|^@$|^$";
-extern std::regex badGitRefRegex;
-
-// A Git revision (a SHA-1 commit hash).
-const static std::string revRegexS = "[0-9a-fA-F]{40}";
-extern std::regex revRegex;
-
-// A ref or revision, or a ref followed by a revision.
-const static std::string refAndOrRevRegex = "(?:(" + revRegexS + ")|(?:(" + refRegexS + ")(?:/(" + revRegexS + "))?))";
-
-const static std::string flakeIdRegexS = "[a-zA-Z][a-zA-Z0-9_-]*";
-extern std::regex flakeIdRegex;
-
 }

src/libutil/util.hh

@@ -12,13 +12,9 @@
 #include <signal.h>
 
 #include <functional>
-#include <limits>
-#include <cstdio>
 #include <map>
 #include <sstream>
 #include <optional>
-#include <future>
-#include <iterator>
 
 #ifndef HAVE_STRUCT_DIRENT_D_TYPE
 #define DT_UNKNOWN 0
@@ -480,43 +476,8 @@ std::optional<typename T::mapped_type> get(const T & map, const typename T::key_
 }
 
 
-/* A callback is a wrapper around a lambda that accepts a valid of
-   type T or an exception. (We abuse std::future<T> to pass the value or
-   exception.) */
 template<typename T>
-class Callback
+class Callback;
-{
-    std::function<void(std::future<T>)> fun;
-    std::atomic_flag done = ATOMIC_FLAG_INIT;
-
-public:
-
-    Callback(std::function<void(std::future<T>)> fun) : fun(fun) { }
-
-    Callback(Callback && callback) : fun(std::move(callback.fun))
-    {
-        auto prev = callback.done.test_and_set();
-        if (prev) done.test_and_set();
-    }
-
-    void operator()(T && t) noexcept
-    {
-        auto prev = done.test_and_set();
-        assert(!prev);
-        std::promise<T> promise;
-        promise.set_value(std::move(t));
-        fun(promise.get_future());
-    }
-
-    void rethrow(const std::exception_ptr & exc = std::current_exception()) noexcept
-    {
-        auto prev = done.test_and_set();
-        assert(!prev);
-        std::promise<T> promise;
-        promise.set_exception(exc);
-        fun(promise.get_future());
-    }
-};
 
 
 /* Start a thread that handles various signals. Also block those signals

src/nix-channel/nix-channel.cc

@@ -76,6 +76,13 @@ static void update(const StringSet & channelNames)
 
     auto store = openStore();
 
+    auto [fd, unpackChannelPath] = createTempFile();
+    writeFull(fd.get(),
+        #include "unpack-channel.nix.gen.hh"
+        );
+    fd = -1;
+    AutoDelete del(unpackChannelPath, false);
+
     // Download each channel.
     Strings exprs;
     for (const auto & channel : channels) {
@@ -87,7 +94,7 @@ static void update(const StringSet & channelNames)
         // We want to download the url to a file to see if it's a tarball while also checking if we
         // got redirected in the process, so that we can grab the various parts of a nix channel
         // definition from a consistent location if the redirect changes mid-download.
-        auto result = fetchers::downloadFile(store, url, Headers {}, std::string(baseNameOf(url)), false);
+        auto result = fetchers::downloadFile(store, url, std::string(baseNameOf(url)), false);
         auto filename = store->toRealPath(result.storePath);
         url = result.effectiveUrl;
 
@@ -104,7 +111,7 @@ static void update(const StringSet & channelNames)
 
         bool unpacked = false;
         if (std::regex_search(filename, std::regex("\\.tar\\.(gz|bz2|xz)$"))) {
-            runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import <nix/unpack-channel.nix> "
+            runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import " + unpackChannelPath +
                         "{ name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; }" });
             unpacked = true;
         }
@@ -112,9 +119,9 @@ static void update(const StringSet & channelNames)
         if (!unpacked) {
             // Download the channel tarball.
             try {
-                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.xz", Headers {}, "nixexprs.tar.xz", false).storePath);
+                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.xz", "nixexprs.tar.xz", false).storePath);
             } catch (FileTransferError & e) {
-                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.bz2", Headers {}, "nixexprs.tar.bz2", false).storePath);
+                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.bz2", "nixexprs.tar.bz2", false).storePath);
             }
         }
 
@@ -125,7 +132,7 @@ static void update(const StringSet & channelNames)
     // Unpack the channel tarballs into the Nix store and install them
     // into the channels profile.
     std::cerr << "unpacking channels...\n";
-    Strings envArgs{ "--profile", profile, "--file", "<nix/unpack-channel.nix>", "--install", "--from-expression" };
+    Strings envArgs{ "--profile", profile, "--file", unpackChannelPath, "--install", "--from-expression" };
     for (auto & expr : exprs)
         envArgs.push_back(std::move(expr));
     envArgs.push_back("--quiet");

src/nix-daemon/nix-daemon.cc

@@ -1,5 +1,6 @@
 #include "shared.hh"
 #include "local-store.hh"
+#include "remote-store.hh"
 #include "util.hh"
 #include "serialise.hh"
 #include "archive.hh"
@@ -285,44 +286,28 @@ static int _main(int argc, char * * argv)
         initPlugins();
 
         if (stdio) {
-            if (getStoreType() == tDaemon) {
+            if (auto store = openUncachedStore().dynamic_pointer_cast<RemoteStore>()) {
-                //  Forward on this connection to the real daemon
+                auto conn = store->openConnectionWrapper();
-                auto socketPath = settings.nixDaemonSocketFile;
+                int from = conn->from.fd;
-                auto s = socket(PF_UNIX, SOCK_STREAM, 0);
+                int to = conn->to.fd;
-                if (s == -1)
-                    throw SysError("creating Unix domain socket");
 
-                auto socketDir = dirOf(socketPath);
+                auto nfds = std::max(from, STDIN_FILENO) + 1;
-                if (chdir(socketDir.c_str()) == -1)
-                    throw SysError("changing to socket directory '%1%'", socketDir);
-
-                auto socketName = std::string(baseNameOf(socketPath));
-                auto addr = sockaddr_un{};
-                addr.sun_family = AF_UNIX;
-                if (socketName.size() + 1 >= sizeof(addr.sun_path))
-                    throw Error("socket name %1% is too long", socketName);
-                strcpy(addr.sun_path, socketName.c_str());
-
-                if (connect(s, (struct sockaddr *) &addr, sizeof(addr)) == -1)
-                    throw SysError("cannot connect to daemon at %1%", socketPath);
-
-                auto nfds = (s > STDIN_FILENO ? s : STDIN_FILENO) + 1;
                 while (true) {
                     fd_set fds;
                     FD_ZERO(&fds);
-                    FD_SET(s, &fds);
+                    FD_SET(from, &fds);
                     FD_SET(STDIN_FILENO, &fds);
                     if (select(nfds, &fds, nullptr, nullptr, nullptr) == -1)
                         throw SysError("waiting for data from client or server");
-                    if (FD_ISSET(s, &fds)) {
+                    if (FD_ISSET(from, &fds)) {
-                        auto res = splice(s, nullptr, STDOUT_FILENO, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
+                        auto res = splice(from, nullptr, STDOUT_FILENO, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
                         if (res == -1)
                             throw SysError("splicing data from daemon socket to stdout");
                         else if (res == 0)
                             throw EndOfFile("unexpected EOF from daemon socket");
                     }
                     if (FD_ISSET(STDIN_FILENO, &fds)) {
-                        auto res = splice(STDIN_FILENO, nullptr, s, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
+                        auto res = splice(STDIN_FILENO, nullptr, to, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
                         if (res == -1)
                             throw SysError("splicing data from stdin to daemon socket");
                         else if (res == 0)

src/nix-env/nix-env.cc

@@ -230,7 +230,7 @@ static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
 {
     DrvNames selectors = drvNamesFromArgs(args);
     if (selectors.empty())
-        selectors.push_back(DrvName("*"));
+        selectors.emplace_back("*");
 
     DrvInfos elems;
     set<unsigned int> done;

src/nix-prefetch-url/nix-prefetch-url.cc

@@ -57,6 +57,7 @@ static int _main(int argc, char * * argv)
         bool fromExpr = false;
         string attrPath;
         bool unpack = false;
+        bool executable = false;
         string name;
 
         struct MyArgs : LegacyArgs, MixEvalArgs
@@ -81,6 +82,8 @@ static int _main(int argc, char * * argv)
             }
             else if (*arg == "--unpack")
                 unpack = true;
+            else if (*arg == "--executable")
+                executable = true;
             else if (*arg == "--name")
                 name = getArg(*arg, arg, end);
             else if (*arg != "" && arg->at(0) == '-')
@@ -175,7 +178,11 @@ static int _main(int argc, char * * argv)
 
             /* Download the file. */
             {
-                AutoCloseFD fd = open(tmpFile.c_str(), O_WRONLY | O_CREAT | O_EXCL, 0600);
+                auto mode = 0600;
+                if (executable)
+                    mode = 0700;
+
+                AutoCloseFD fd = open(tmpFile.c_str(), O_WRONLY | O_CREAT | O_EXCL, mode);
                 if (!fd) throw SysError("creating temporary file '%s'", tmpFile);
 
                 FdSink sink(fd.get());
@@ -201,7 +208,7 @@ static int _main(int argc, char * * argv)
                     tmpFile = unpacked;
             }
 
-            const auto method = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+            const auto method = unpack || executable ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
 
             auto info = store->addToStoreSlow(name, tmpFile, method, ht, expectedHash);
             storePath = info.path;

src/nix/bundle.cc

@@ -98,14 +98,14 @@ struct CmdBundle : InstallableCommand
         if (!evalState->isDerivation(*vRes))
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
 
-        auto attr1 = vRes->attrs->find(evalState->sDrvPath);
+        auto attr1 = vRes->attrs->get(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);
+        auto attr2 = vRes->attrs->get(evalState->sOutPath);
         if (!attr2)
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
 

src/nix/doctor.cc

@@ -49,9 +49,7 @@ struct CmdDoctor : StoreCommand
     {
         logger->log("Running checks against store uri: " + store->getUri());
 
-        auto type = getStoreType();
+        if (store.dynamic_pointer_cast<LocalFSStore>()) {
-
-        if (type < tOther) {
             success &= checkNixInPath();
             success &= checkProfileRoots(store);
         }

src/nix/hash.cc

@@ -44,6 +44,7 @@ struct CmdHash : Command
         switch (mode) {
         case FileIngestionMethod::Flat:
             d = "print cryptographic hash of a regular file";
+            break;
         case FileIngestionMethod::Recursive:
             d = "print cryptographic hash of the NAR serialisation of a path";
         };

src/nix/local.mk

@@ -29,3 +29,5 @@ $(eval $(call install-symlink, $(bindir)/nix, $(libexecdir)/nix/build-remote))
 src/nix-env/user-env.cc: src/nix-env/buildenv.nix.gen.hh
 
 src/nix/develop.cc: src/nix/get-env.sh.gen.hh
+
+src/nix-channel/nix-channel.cc: src/nix-channel/unpack-channel.nix.gen.hh

src/resolve-system-dependencies/resolve-system-dependencies.cc

@@ -111,11 +111,7 @@ std::set<std::string> runResolver(const Path & filename)
 
 bool isSymlink(const Path & path)
 {
-    struct stat st;
+    return S_ISLNK(lstat(path).st_mode);
-    if (lstat(path.c_str(), &st) == -1)
-        throw SysError("getting attributes of path '%1%'", path);
-
-    return S_ISLNK(st.st_mode);
 }
 
 Path resolveSymlink(const Path & path)

tests/content-addressed.nix

@@ -29,4 +29,26 @@ rec {
     outputHashMode = "recursive";
     outputHashAlgo = "sha256";
   };
+  dependentCA = mkDerivation {
+    name = "dependent";
+    buildCommand = ''
+      echo "building a dependent derivation"
+      mkdir -p $out
+      echo ${rootCA}/hello > $out/dep
+    '';
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+  };
+  transitivelyDependentCA = mkDerivation {
+    name = "transitively-dependent";
+    buildCommand = ''
+      echo "building transitively-dependent"
+      cat ${dependentCA}/dep
+      echo ${dependentCA} > $out
+    '';
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+  };
 }

tests/content-addressed.sh

@@ -2,16 +2,26 @@
 
 source common.sh
 
-clearStore
-clearCache
-
-export REMOTE_STORE=file://$cacheDir
-
 drv=$(nix-instantiate --experimental-features ca-derivations ./content-addressed.nix -A rootCA --arg seed 1)
 nix --experimental-features 'nix-command ca-derivations' show-derivation --derivation "$drv" --arg seed 1
 
-commonArgs=("--experimental-features" "ca-derivations" "./content-addressed.nix" "-A" "rootCA" "--no-out-link")
+testDerivation () {
-out1=$(nix-build "${commonArgs[@]}" ./content-addressed.nix --arg seed 1)
+    local derivationPath=$1
-out2=$(nix-build "${commonArgs[@]}" ./content-addressed.nix --arg seed 2)
+    local commonArgs=("--experimental-features" "ca-derivations" "./content-addressed.nix" "-A" "$derivationPath" "--no-out-link")
+    local out1 out2
+    out1=$(nix-build "${commonArgs[@]}" --arg seed 1)
+    out2=$(nix-build "${commonArgs[@]}" --arg seed 2 "${secondSeedArgs[@]}")
+    test "$out1" == "$out2"
+}
 
-test $out1 == $out2
+testDerivation rootCA
+# The seed only changes the root derivation, and not it's output, so the
+# dependent derivations should only need to be built once.
+secondSeedArgs=(-j0)
+# Don't directly build depenentCA, that way we'll make sure we dodn't rely on
+# dependent derivations always being already built.
+#testDerivation dependentCA
+testDerivation transitivelyDependentCA
+
+nix-instantiate --experimental-features ca-derivations ./content-addressed.nix -A rootCA --arg seed 5
+nix-collect-garbage --experimental-features ca-derivations --option keep-derivations true

tests/local.mk

@@ -15,6 +15,7 @@ nix_tests = \
   linux-sandbox.sh \
   build-dry.sh \
   build-remote-input-addressed.sh \
+  ssh-relay.sh \
   nar-access.sh \
   structured-attrs.sh \
   fetchGit.sh \

tests/recursive.sh

@@ -9,9 +9,8 @@ rm -f $TEST_ROOT/result
 
 export unreachable=$(nix add-to-store ./recursive.sh)
 
-nix --experimental-features 'nix-command recursive-nix' build -o $TEST_ROOT/result -L --impure --expr '
+NIX_BIN_DIR=$(dirname $(type -p nix)) nix --experimental-features 'nix-command recursive-nix' build -o $TEST_ROOT/result -L --impure --expr '
   with import ./config.nix;
-  with import <nix/config.nix>;
   mkDerivation {
     name = "recursive";
     dummy = builtins.toFile "dummy" "bla bla";
@@ -24,9 +23,10 @@ nix --experimental-features 'nix-command recursive-nix' build -o $TEST_ROOT/resu
 
     buildCommand = '\'\''
       mkdir $out
-      PATH=${nixBinDir}:$PATH
       opts="--experimental-features nix-command"
 
+      PATH=${builtins.getEnv "NIX_BIN_DIR"}:$PATH
+
       # Check that we can query/build paths in our input closure.
       nix $opts path-info $dummy
       nix $opts build $dummy

tests/repair.sh

@@ -13,14 +13,14 @@ hash=$(nix-hash $path2)
 chmod u+w $path2
 touch $path2/bad
 
-if nix-store --verify --check-contents -v; then
+(! nix-store --verify --check-contents -v)
-    echo "nix-store --verify succeeded unexpectedly" >&2
-    exit 1
-fi
 
 # The path can be repaired by rebuilding the derivation.
 nix-store --verify --check-contents --repair
 
+(! [ -e $path2/bad ])
+(! [ -w $path2 ])
+
 nix-store --verify-path $path2
 
 # Re-corrupt and delete the deriver. Now --verify --repair should
@@ -30,10 +30,7 @@ touch $path2/bad
 
 nix-store --delete $(nix-store -qd $path2)
 
-if nix-store --verify --check-contents --repair; then
+(! nix-store --verify --check-contents --repair)
-    echo "nix-store --verify --repair succeeded unexpectedly" >&2
-    exit 1
-fi
 
 nix-build dependencies.nix -o $TEST_ROOT/result --repair
 

tests/simple.sh

@@ -10,13 +10,15 @@ outPath=$(nix-store -rvv "$drvPath")
 
 echo "output path is $outPath"
 
+(! [ -w $outPath ])
+
 text=$(cat "$outPath"/hello)
 if test "$text" != "Hello World!"; then exit 1; fi
 
 # Directed delete: $outPath is not reachable from a root, so it should
 # be deleteable.
 nix-store --delete $outPath
-if test -e $outPath/hello; then false; fi
+(! [ -e $outPath/hello ])
 
 outPath="$(NIX_REMOTE=local?store=/foo\&real=$TEST_ROOT/real-store nix-instantiate --readonly-mode hash-check.nix)"
 if test "$outPath" != "/foo/lfy1s6ca46rm5r6w4gg9hc0axiakjcnm-dependencies.drv"; then

tests/ssh-relay.sh

@@ -0,0 +1,16 @@
+source common.sh
+
+echo foo > $TEST_ROOT/hello.sh
+
+ssh_localhost=ssh://localhost
+remote_store=?remote-store=$ssh_localhost
+
+store=$ssh_localhost
+
+store+=$remote_store
+store+=$remote_store
+store+=$remote_store
+
+out=$(nix add-to-store --store "$store" $TEST_ROOT/hello.sh)
+
+[ foo = $(< $out) ]

tests/tarball.sh

@@ -17,7 +17,7 @@ test_tarball() {
     local compressor="$2"
 
     tarball=$TEST_ROOT/tarball.tar$ext
-    (cd $TEST_ROOT && tar c tarball) | $compressor > $tarball
+    (cd $TEST_ROOT && tar cf - tarball) | $compressor > $tarball
 
     nix-env -f file://$tarball -qa --out-path | grep -q dependencies