Introduce DerivationOptions

This is a first step towards PR #10760, and the issues it addresses.
See the Doxygen for details.

Thanks to these changes, we are able to drastically restrict how the
rest of the code-base uses `ParseDerivation`.

Co-Authored-By: HaeNoe <git@haenoe.party>

src/libstore-tests/derivation-advanced-attrs.cc

@@ -3,13 +3,15 @@
 
 #include "experimental-features.hh"
 #include "derivations.hh"
-
-#include "tests/libstore.hh"
-#include "tests/characterization.hh"
+#include "derivations.hh"
+#include "derivation-options.hh"
 #include "parsed-derivations.hh"
 #include "types.hh"
 #include "json-utils.hh"
 
+#include "tests/libstore.hh"
+#include "tests/characterization.hh"
+
 namespace nix {
 
 using nlohmann::json;
@@ -80,21 +82,30 @@ TEST_F(DerivationAdvancedAttrsTest, Derivation_advancedAttributes_defaults)
         auto drvPath = writeDerivation(*store, got, NoRepair, true);
 
         ParsedDerivation parsedDrv(drvPath, got);
+        DerivationOptions options = DerivationOptions::fromParsedDerivation(parsedDrv);
 
-        EXPECT_EQ(parsedDrv.getStringAttr("__sandboxProfile").value_or(""), "");
-        EXPECT_EQ(parsedDrv.getBoolAttr("__noChroot"), false);
-        EXPECT_EQ(parsedDrv.getStringsAttr("__impureHostDeps").value_or(Strings()), Strings());
-        EXPECT_EQ(parsedDrv.getStringsAttr("impureEnvVars").value_or(Strings()), Strings());
-        EXPECT_EQ(parsedDrv.getBoolAttr("__darwinAllowLocalNetworking"), false);
-        EXPECT_EQ(parsedDrv.getStringsAttr("allowedReferences"), std::nullopt);
-        EXPECT_EQ(parsedDrv.getStringsAttr("allowedRequisites"), std::nullopt);
-        EXPECT_EQ(parsedDrv.getStringsAttr("disallowedReferences"), std::nullopt);
-        EXPECT_EQ(parsedDrv.getStringsAttr("disallowedRequisites"), std::nullopt);
-        EXPECT_EQ(parsedDrv.getRequiredSystemFeatures(), StringSet());
-        EXPECT_EQ(parsedDrv.canBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.willBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.substitutesAllowed(), true);
-        EXPECT_EQ(parsedDrv.useUidRange(), false);
+        EXPECT_TRUE(!parsedDrv.hasStructuredAttrs());
+
+        EXPECT_EQ(options.additionalSandboxProfile, "");
+        EXPECT_EQ(options.noChroot, false);
+        EXPECT_EQ(options.impureHostDeps, StringSet{});
+        EXPECT_EQ(options.impureEnvVars, StringSet{});
+        EXPECT_EQ(options.allowLocalNetworking, false);
+        {
+            auto * checksForAllOutputs_ = std::get_if<0>(&options.outputChecks);
+            ASSERT_TRUE(checksForAllOutputs_ != nullptr);
+            auto & checksForAllOutputs = *checksForAllOutputs_;
+
+            EXPECT_EQ(checksForAllOutputs.allowedReferences, std::nullopt);
+            EXPECT_EQ(checksForAllOutputs.allowedRequisites, std::nullopt);
+            EXPECT_EQ(checksForAllOutputs.disallowedReferences, StringSet{});
+            EXPECT_EQ(checksForAllOutputs.disallowedRequisites, StringSet{});
+        }
+        EXPECT_EQ(options.getRequiredSystemFeatures(got), StringSet());
+        EXPECT_EQ(options.canBuildLocally(*store, got), false);
+        EXPECT_EQ(options.willBuildLocally(*store, got), false);
+        EXPECT_EQ(options.substitutesAllowed(), true);
+        EXPECT_EQ(options.useUidRange(got), false);
     });
 };
 
@@ -106,29 +117,36 @@ TEST_F(DerivationAdvancedAttrsTest, Derivation_advancedAttributes)
         auto drvPath = writeDerivation(*store, got, NoRepair, true);
 
         ParsedDerivation parsedDrv(drvPath, got);
+        DerivationOptions options = DerivationOptions::fromParsedDerivation(parsedDrv);
 
         StringSet systemFeatures{"rainbow", "uid-range"};
 
-        EXPECT_EQ(parsedDrv.getStringAttr("__sandboxProfile").value_or(""), "sandcastle");
-        EXPECT_EQ(parsedDrv.getBoolAttr("__noChroot"), true);
-        EXPECT_EQ(parsedDrv.getStringsAttr("__impureHostDeps").value_or(Strings()), Strings{"/usr/bin/ditto"});
-        EXPECT_EQ(parsedDrv.getStringsAttr("impureEnvVars").value_or(Strings()), Strings{"UNICORN"});
-        EXPECT_EQ(parsedDrv.getBoolAttr("__darwinAllowLocalNetworking"), true);
-        EXPECT_EQ(
-            parsedDrv.getStringsAttr("allowedReferences"), Strings{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
-        EXPECT_EQ(
-            parsedDrv.getStringsAttr("allowedRequisites"), Strings{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
-        EXPECT_EQ(
-            parsedDrv.getStringsAttr("disallowedReferences"),
-            Strings{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
-        EXPECT_EQ(
-            parsedDrv.getStringsAttr("disallowedRequisites"),
-            Strings{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
-        EXPECT_EQ(parsedDrv.getRequiredSystemFeatures(), systemFeatures);
-        EXPECT_EQ(parsedDrv.canBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.willBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.substitutesAllowed(), false);
-        EXPECT_EQ(parsedDrv.useUidRange(), true);
+        EXPECT_TRUE(!parsedDrv.hasStructuredAttrs());
+
+        EXPECT_EQ(options.additionalSandboxProfile, "sandcastle");
+        EXPECT_EQ(options.noChroot, true);
+        EXPECT_EQ(options.impureHostDeps, StringSet{"/usr/bin/ditto"});
+        EXPECT_EQ(options.impureEnvVars, StringSet{"UNICORN"});
+        EXPECT_EQ(options.allowLocalNetworking, true);
+        {
+            auto * checksForAllOutputs_ = std::get_if<0>(&options.outputChecks);
+            ASSERT_TRUE(checksForAllOutputs_ != nullptr);
+            auto & checksForAllOutputs = *checksForAllOutputs_;
+
+            EXPECT_EQ(
+                checksForAllOutputs.allowedReferences, StringSet{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
+            EXPECT_EQ(
+                checksForAllOutputs.allowedRequisites, StringSet{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
+            EXPECT_EQ(
+                checksForAllOutputs.disallowedReferences, StringSet{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
+            EXPECT_EQ(
+                checksForAllOutputs.disallowedRequisites, StringSet{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
+        }
+        EXPECT_EQ(options.getRequiredSystemFeatures(got), systemFeatures);
+        EXPECT_EQ(options.canBuildLocally(*store, got), false);
+        EXPECT_EQ(options.willBuildLocally(*store, got), false);
+        EXPECT_EQ(options.substitutesAllowed(), false);
+        EXPECT_EQ(options.useUidRange(got), true);
     });
 };
 
@@ -140,27 +158,29 @@ TEST_F(DerivationAdvancedAttrsTest, Derivation_advancedAttributes_structuredAttr
         auto drvPath = writeDerivation(*store, got, NoRepair, true);
 
         ParsedDerivation parsedDrv(drvPath, got);
+        DerivationOptions options = DerivationOptions::fromParsedDerivation(parsedDrv);
 
-        EXPECT_EQ(parsedDrv.getStringAttr("__sandboxProfile").value_or(""), "");
-        EXPECT_EQ(parsedDrv.getBoolAttr("__noChroot"), false);
-        EXPECT_EQ(parsedDrv.getStringsAttr("__impureHostDeps").value_or(Strings()), Strings());
-        EXPECT_EQ(parsedDrv.getStringsAttr("impureEnvVars").value_or(Strings()), Strings());
-        EXPECT_EQ(parsedDrv.getBoolAttr("__darwinAllowLocalNetworking"), false);
+        EXPECT_TRUE(parsedDrv.hasStructuredAttrs());
+
+        EXPECT_EQ(options.additionalSandboxProfile, "");
+        EXPECT_EQ(options.noChroot, false);
+        EXPECT_EQ(options.impureHostDeps, StringSet{});
+        EXPECT_EQ(options.impureEnvVars, StringSet{});
+        EXPECT_EQ(options.allowLocalNetworking, false);
 
         {
-            auto structuredAttrs_ = parsedDrv.getStructuredAttrs();
-            ASSERT_TRUE(structuredAttrs_);
-            auto & structuredAttrs = *structuredAttrs_;
+            auto * checksPerOutput_ = std::get_if<1>(&options.outputChecks);
+            ASSERT_TRUE(checksPerOutput_ != nullptr);
+            auto & checksPerOutput = *checksPerOutput_;
 
-            auto outputChecks_ = get(structuredAttrs, "outputChecks");
-            ASSERT_FALSE(outputChecks_);
+            EXPECT_EQ(checksPerOutput.size(), 0);
         }
 
-        EXPECT_EQ(parsedDrv.getRequiredSystemFeatures(), StringSet());
-        EXPECT_EQ(parsedDrv.canBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.willBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.substitutesAllowed(), true);
-        EXPECT_EQ(parsedDrv.useUidRange(), false);
+        EXPECT_EQ(options.getRequiredSystemFeatures(got), StringSet());
+        EXPECT_EQ(options.canBuildLocally(*store, got), false);
+        EXPECT_EQ(options.willBuildLocally(*store, got), false);
+        EXPECT_EQ(options.substitutesAllowed(), true);
+        EXPECT_EQ(options.useUidRange(got), false);
     });
 };
 
@@ -172,62 +192,52 @@ TEST_F(DerivationAdvancedAttrsTest, Derivation_advancedAttributes_structuredAttr
         auto drvPath = writeDerivation(*store, got, NoRepair, true);
 
         ParsedDerivation parsedDrv(drvPath, got);
+        DerivationOptions options = DerivationOptions::fromParsedDerivation(parsedDrv);
 
         StringSet systemFeatures{"rainbow", "uid-range"};
 
-        EXPECT_EQ(parsedDrv.getStringAttr("__sandboxProfile").value_or(""), "sandcastle");
-        EXPECT_EQ(parsedDrv.getBoolAttr("__noChroot"), true);
-        EXPECT_EQ(parsedDrv.getStringsAttr("__impureHostDeps").value_or(Strings()), Strings{"/usr/bin/ditto"});
-        EXPECT_EQ(parsedDrv.getStringsAttr("impureEnvVars").value_or(Strings()), Strings{"UNICORN"});
-        EXPECT_EQ(parsedDrv.getBoolAttr("__darwinAllowLocalNetworking"), true);
+        EXPECT_TRUE(parsedDrv.hasStructuredAttrs());
+
+        EXPECT_EQ(options.additionalSandboxProfile, "sandcastle");
+        EXPECT_EQ(options.noChroot, true);
+        EXPECT_EQ(options.impureHostDeps, StringSet{"/usr/bin/ditto"});
+        EXPECT_EQ(options.impureEnvVars, StringSet{"UNICORN"});
+        EXPECT_EQ(options.allowLocalNetworking, true);
 
         {
-            auto structuredAttrs_ = parsedDrv.getStructuredAttrs();
-            ASSERT_TRUE(structuredAttrs_);
-            auto & structuredAttrs = *structuredAttrs_;
-
-            auto outputChecks_ = get(structuredAttrs, "outputChecks");
-            ASSERT_TRUE(outputChecks_);
-            auto & outputChecks = *outputChecks_;
-
             {
-                auto output_ = get(outputChecks, "out");
+                auto output_ = get(std::get<1>(options.outputChecks), "out");
                 ASSERT_TRUE(output_);
                 auto & output = *output_;
-                EXPECT_EQ(
-                    get(output, "allowedReferences")->get<Strings>(),
-                    Strings{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
-                EXPECT_EQ(
-                    get(output, "allowedRequisites")->get<Strings>(),
-                    Strings{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
+
+                EXPECT_EQ(output.allowedReferences, StringSet{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
+                EXPECT_EQ(output.allowedRequisites, StringSet{"/nix/store/3c08bzb71z4wiag719ipjxr277653ynp-foo"});
             }
 
             {
-                auto output_ = get(outputChecks, "bin");
+                auto output_ = get(std::get<1>(options.outputChecks), "bin");
                 ASSERT_TRUE(output_);
                 auto & output = *output_;
-                EXPECT_EQ(
-                    get(output, "disallowedReferences")->get<Strings>(),
-                    Strings{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
-                EXPECT_EQ(
-                    get(output, "disallowedRequisites")->get<Strings>(),
-                    Strings{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
+
+                EXPECT_EQ(output.disallowedReferences, StringSet{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
+                EXPECT_EQ(output.disallowedRequisites, StringSet{"/nix/store/7rhsm8i393hm1wcsmph782awg1hi2f7x-bar"});
             }
 
             {
-                auto output_ = get(outputChecks, "dev");
+                auto output_ = get(std::get<1>(options.outputChecks), "dev");
                 ASSERT_TRUE(output_);
                 auto & output = *output_;
-                EXPECT_EQ(get(output, "maxSize")->get<uint64_t>(), 789);
-                EXPECT_EQ(get(output, "maxClosureSize")->get<uint64_t>(), 5909);
+
+                EXPECT_EQ(output.maxSize, 789);
+                EXPECT_EQ(output.maxClosureSize, 5909);
             }
         }
 
-        EXPECT_EQ(parsedDrv.getRequiredSystemFeatures(), systemFeatures);
-        EXPECT_EQ(parsedDrv.canBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.willBuildLocally(*store), false);
-        EXPECT_EQ(parsedDrv.substitutesAllowed(), false);
-        EXPECT_EQ(parsedDrv.useUidRange(), true);
+        EXPECT_EQ(options.getRequiredSystemFeatures(got), systemFeatures);
+        EXPECT_EQ(options.canBuildLocally(*store, got), false);
+        EXPECT_EQ(options.willBuildLocally(*store, got), false);
+        EXPECT_EQ(options.substitutesAllowed(), false);
+        EXPECT_EQ(options.useUidRange(got), true);
     });
 };
 

src/libstore/build/derivation-goal.cc

@@ -168,6 +168,7 @@ Goal::Co DerivationGoal::haveDerivation()
     trace("have derivation");
 
     parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv);
+    drvOptions = std::make_unique<DerivationOptions>(DerivationOptions::fromParsedDerivation(*parsedDrv));
 
     if (!drv->type().hasKnownOutputPaths())
         experimentalFeatureSettings.require(Xp::CaDerivations);
@@ -224,7 +225,7 @@ Goal::Co DerivationGoal::haveDerivation()
     /* We are first going to try to create the invalid output paths
        through substitutes.  If that doesn't work, we'll build
        them. */
-    if (settings.useSubstitutes && parsedDrv->substitutesAllowed())
+    if (settings.useSubstitutes && drvOptions->substitutesAllowed())
         for (auto & [outputName, status] : initialOutputs) {
             if (!status.wanted) continue;
             if (!status.known)
@@ -614,7 +615,7 @@ Goal::Co DerivationGoal::tryToBuild()
        `preferLocalBuild' set.  Also, check and repair modes are only
        supported for local builds. */
     bool buildLocally =
-        (buildMode != bmNormal || parsedDrv->willBuildLocally(worker.store))
+        (buildMode != bmNormal || drvOptions->willBuildLocally(worker.store, *drv))
         && settings.maxBuildJobs.get() != 0;
 
     if (!buildLocally) {
@@ -1110,7 +1111,7 @@ HookReply DerivationGoal::tryBuildHook()
             << (worker.getNrLocalBuilds() < settings.maxBuildJobs ? 1 : 0)
             << drv->platform
             << worker.store.printStorePath(drvPath)
-            << parsedDrv->getRequiredSystemFeatures();
+            << drvOptions->getRequiredSystemFeatures(*drv);
         worker.hook->sink.flush();
 
         /* Read the first line of input, which should be a word indicating

src/libstore/build/derivation-goal.hh

@@ -2,6 +2,7 @@
 ///@file
 
 #include "parsed-derivations.hh"
+#include "derivation-options.hh"
 #ifndef _WIN32
 #  include "user-lock.hh"
 #endif
@@ -147,6 +148,7 @@ struct DerivationGoal : public Goal
     std::unique_ptr<Derivation> drv;
 
     std::unique_ptr<ParsedDerivation> parsedDrv;
+    std::unique_ptr<DerivationOptions> drvOptions;
 
     /**
      * The remainder is state held during the build.

src/libstore/derivation-options.cc

@@ -0,0 +1,274 @@
+#include "derivation-options.hh"
+#include "json-utils.hh"
+#include "parsed-derivations.hh"
+#include "types.hh"
+#include "util.hh"
+#include <optional>
+#include <string>
+#include <variant>
+
+namespace nix {
+
+using OutputChecks = DerivationOptions::OutputChecks;
+
+using OutputChecksVariant = std::variant<OutputChecks, std::map<std::string, OutputChecks>>;
+
+DerivationOptions DerivationOptions::fromParsedDerivation(const ParsedDerivation & parsed, bool shouldWarn)
+{
+    DerivationOptions defaults = {};
+
+    auto structuredAttrs = parsed.structuredAttrs.get();
+
+    if (shouldWarn && structuredAttrs) {
+        if (get(*structuredAttrs, "allowedReferences")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'allowedReferences'; use 'outputChecks' instead");
+        }
+        if (get(*structuredAttrs, "allowedRequisites")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'allowedRequisites'; use 'outputChecks' instead");
+        }
+        if (get(*structuredAttrs, "disallowedRequisites")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'disallowedRequisites'; use 'outputChecks' instead");
+        }
+        if (get(*structuredAttrs, "disallowedReferences")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'disallowedReferences'; use 'outputChecks' instead");
+        }
+        if (get(*structuredAttrs, "maxSize")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'maxSize'; use 'outputChecks' instead");
+        }
+        if (get(*structuredAttrs, "maxClosureSize")) {
+            warn(
+                "'structuredAttrs' disables the effect of the top-level attribute 'maxClosureSize'; use 'outputChecks' instead");
+        }
+    }
+
+    return {
+        .outputChecks = [&]() -> OutputChecksVariant {
+            if (auto structuredAttrs = parsed.structuredAttrs.get()) {
+                std::map<std::string, OutputChecks> res;
+                if (auto outputChecks = get(*structuredAttrs, "outputChecks")) {
+                    for (auto & [outputName, output] : getObject(*outputChecks)) {
+                        OutputChecks checks;
+
+                        if (auto maxSize = get(output, "maxSize"))
+                            checks.maxSize = maxSize->get<uint64_t>();
+
+                        if (auto maxClosureSize = get(output, "maxClosureSize"))
+                            checks.maxClosureSize = maxClosureSize->get<uint64_t>();
+
+                        auto get_ = [&](const std::string & name) -> std::optional<StringSet> {
+                            if (auto i = get(output, name)) {
+                                StringSet res;
+                                for (auto j = i->begin(); j != i->end(); ++j) {
+                                    if (!j->is_string())
+                                        throw Error("attribute '%s' must be a list of strings", name);
+                                    res.insert(j->get<std::string>());
+                                }
+                                checks.disallowedRequisites = res;
+                                return res;
+                            }
+                            return {};
+                        };
+
+                        checks.allowedReferences = get_("allowedReferences");
+                        checks.allowedRequisites = get_("allowedRequisites");
+                        checks.disallowedReferences = get_("disallowedReferences").value_or(StringSet{});
+                        checks.disallowedRequisites = get_("disallowedRequisites").value_or(StringSet{});
+                        ;
+
+                        res.insert_or_assign(outputName, std::move(checks));
+                    }
+                }
+                return res;
+            } else {
+                return OutputChecks{
+                    // legacy non-structured-attributes case
+                    .ignoreSelfRefs = true,
+                    .allowedReferences = parsed.getStringSetAttr("allowedReferences"),
+                    .disallowedReferences = parsed.getStringSetAttr("disallowedReferences").value_or(StringSet{}),
+                    .allowedRequisites = parsed.getStringSetAttr("allowedRequisites"),
+                    .disallowedRequisites = parsed.getStringSetAttr("disallowedRequisites").value_or(StringSet{}),
+                };
+            }
+        }(),
+        .unsafeDiscardReferences =
+            [&] {
+                std::map<std::string, bool> res;
+
+                if (auto structuredAttrs = parsed.structuredAttrs.get()) {
+                    if (auto udr = get(*structuredAttrs, "unsafeDiscardReferences")) {
+                        for (auto & [outputName, output] : getObject(*udr)) {
+                            if (!output.is_boolean())
+                                throw Error("attribute 'unsafeDiscardReferences.\"%s\"' must be a Boolean", outputName);
+                            res.insert_or_assign(outputName, output.get<bool>());
+                        }
+                    }
+                }
+
+                return res;
+            }(),
+        .passAsFile =
+            [&] {
+                StringSet res;
+                if (auto * passAsFileString = get(parsed.drv.env, "passAsFile")) {
+                    if (parsed.hasStructuredAttrs()) {
+                        if (shouldWarn) {
+                            warn(
+                                "'structuredAttrs' disables the effect of the top-level attribute 'passAsFile'; because all JSON is always passed via file");
+                        }
+                    } else {
+                        res = tokenizeString<StringSet>(*passAsFileString);
+                    }
+                }
+                return res;
+            }(),
+        .additionalSandboxProfile =
+            parsed.getStringAttr("__sandboxProfile").value_or(defaults.additionalSandboxProfile),
+        .noChroot = parsed.getBoolAttr("__noChroot", defaults.noChroot),
+        .impureHostDeps = parsed.getStringSetAttr("__impureHostDeps").value_or(defaults.impureHostDeps),
+        .impureEnvVars = parsed.getStringSetAttr("impureEnvVars").value_or(defaults.impureEnvVars),
+        .allowLocalNetworking = parsed.getBoolAttr("__darwinAllowLocalNetworking", defaults.allowLocalNetworking),
+        .requiredSystemFeatures =
+            parsed.getStringSetAttr("requiredSystemFeatures").value_or(defaults.requiredSystemFeatures),
+        .preferLocalBuild = parsed.getBoolAttr("preferLocalBuild", defaults.preferLocalBuild),
+        .allowSubstitutes = parsed.getBoolAttr("allowSubstitutes", defaults.allowSubstitutes),
+    };
+}
+
+StringSet DerivationOptions::getRequiredSystemFeatures(const BasicDerivation & drv) const
+{
+    // FIXME: cache this?
+    StringSet res;
+    for (auto & i : requiredSystemFeatures)
+        res.insert(i);
+    if (!drv.type().hasKnownOutputPaths())
+        res.insert("ca-derivations");
+    return res;
+}
+
+bool DerivationOptions::canBuildLocally(Store & localStore, const BasicDerivation & drv) const
+{
+    if (drv.platform != settings.thisSystem.get() && !settings.extraPlatforms.get().count(drv.platform)
+        && !drv.isBuiltin())
+        return false;
+
+    if (settings.maxBuildJobs.get() == 0 && !drv.isBuiltin())
+        return false;
+
+    for (auto & feature : getRequiredSystemFeatures(drv))
+        if (!localStore.systemFeatures.get().count(feature))
+            return false;
+
+    return true;
+}
+
+bool DerivationOptions::willBuildLocally(Store & localStore, const BasicDerivation & drv) const
+{
+    return preferLocalBuild && canBuildLocally(localStore, drv);
+}
+
+bool DerivationOptions::substitutesAllowed() const
+{
+    return settings.alwaysAllowSubstitutes ? true : allowSubstitutes;
+}
+
+bool DerivationOptions::useUidRange(const BasicDerivation & drv) const
+{
+    return getRequiredSystemFeatures(drv).count("uid-range");
+}
+
+}
+
+namespace nlohmann {
+
+using namespace nix;
+
+DerivationOptions adl_serializer<DerivationOptions>::from_json(const json & json)
+{
+    return {
+        .outputChecks = [&]() -> OutputChecksVariant {
+            auto outputChecks = getObject(valueAt(json, "outputChecks"));
+
+            auto forAllOutputsOpt = optionalValueAt(outputChecks, "forAllOutputs");
+            auto perOutputOpt = optionalValueAt(outputChecks, "perOutput");
+
+            if (forAllOutputsOpt && !perOutputOpt) {
+                return static_cast<OutputChecks>(*forAllOutputsOpt);
+            } else if (perOutputOpt && !forAllOutputsOpt) {
+                return static_cast<std::map<std::string, OutputChecks>>(*perOutputOpt);
+            } else {
+                throw Error("Exactly one of 'perOutput' or 'forAllOutputs' is required");
+            }
+        }(),
+
+        .unsafeDiscardReferences = valueAt(json, "unsafeDiscardReferences"),
+        .passAsFile = getStringSet(valueAt(json, "passAsFile")),
+
+        .additionalSandboxProfile = getString(valueAt(json, "additionalSandboxProfile")),
+        .noChroot = getBoolean(valueAt(json, "noChroot")),
+        .impureHostDeps = getStringSet(valueAt(json, "impureHostDeps")),
+        .impureEnvVars = getStringSet(valueAt(json, "impureEnvVars")),
+        .allowLocalNetworking = getBoolean(valueAt(json, "allowLocalNetworking")),
+
+        .requiredSystemFeatures = getStringSet(valueAt(json, "requiredSystemFeatures")),
+        .preferLocalBuild = getBoolean(valueAt(json, "preferLocalBuild")),
+        .allowSubstitutes = getBoolean(valueAt(json, "allowSubstitutes")),
+    };
+}
+
+void adl_serializer<DerivationOptions>::to_json(json & json, DerivationOptions o)
+{
+    json["outputChecks"] = std::visit(
+        overloaded{
+            [&](const OutputChecks & checks) {
+                nlohmann::json outputChecks;
+                outputChecks["forAllOutputs"] = checks;
+                return outputChecks;
+            },
+            [&](const std::map<std::string, OutputChecks> & checksPerOutput) {
+                nlohmann::json outputChecks;
+                outputChecks["perOutput"] = checksPerOutput;
+                return outputChecks;
+            },
+        },
+        o.outputChecks);
+
+    json["unsafeDiscardReferences"] = o.unsafeDiscardReferences;
+    json["passAsFile"] = o.passAsFile;
+
+    json["additionalSandboxProfile"] = o.additionalSandboxProfile;
+    json["noChroot"] = o.noChroot;
+    json["impureHostDeps"] = o.impureHostDeps;
+    json["impureEnvVars"] = o.impureEnvVars;
+    json["allowLocalNetworking"] = o.allowLocalNetworking;
+
+    json["requiredSystemFeatures"] = o.requiredSystemFeatures;
+    json["preferLocalBuild"] = o.preferLocalBuild;
+    json["allowSubstitutes"] = o.allowSubstitutes;
+}
+
+DerivationOptions::OutputChecks adl_serializer<DerivationOptions::OutputChecks>::from_json(const json & json)
+{
+    return {
+        .ignoreSelfRefs = getBoolean(valueAt(json, "ignoreSelfRefs")),
+        .allowedReferences = nullableValueAt(json, "allowedReferences"),
+        .disallowedReferences = getStringSet(valueAt(json, "disallowedReferences")),
+        .allowedRequisites = nullableValueAt(json, "allowedRequisites"),
+        .disallowedRequisites = getStringSet(valueAt(json, "disallowedRequisites")),
+    };
+}
+
+void adl_serializer<DerivationOptions::OutputChecks>::to_json(json & json, DerivationOptions::OutputChecks c)
+{
+    json["ignoreSelfRefs"] = c.ignoreSelfRefs;
+    json["allowedReferences"] = c.allowedReferences;
+    json["disallowedReferences"] = c.disallowedReferences;
+    json["allowedRequisites"] = c.allowedRequisites;
+    json["disallowedRequisites"] = c.disallowedRequisites;
+}
+
+}

src/libstore/derivation-options.hh

@@ -0,0 +1,185 @@
+#pragma once
+///@file
+
+#include <cstdint>
+#include <nlohmann/json.hpp>
+#include <optional>
+#include <variant>
+
+#include "types.hh"
+#include "json-impls.hh"
+
+namespace nix {
+
+class Store;
+struct BasicDerivation;
+class ParsedDerivation;
+
+/**
+ * This represents all the special options on a `Derivation`.
+ *
+ * Currently, these options are parsed from the environment variables
+ * with the aid of `ParsedDerivation`.
+ *
+ * The first goal of this data type is to make sure that no other code
+ * uses `ParsedDerivation` to ad-hoc parse some additional options. That
+ * ensures this data type is up to date and fully correct.
+ *
+ * The second goal of this data type is to allow an alternative to
+ * hackily parsing the options from the environment variables. The ATerm
+ * format cannot change, but in alternatives to it (like the JSON
+ * format), we have the option of instead storing the options
+ * separately. That would be nice to separate concerns, and not make any
+ * environment variable names magical.
+ */
+struct DerivationOptions
+{
+    struct OutputChecks
+    {
+        bool ignoreSelfRefs = false;
+        std::optional<uint64_t> maxSize, maxClosureSize;
+
+        /**
+         * env: allowedReferences
+         *
+         * A value of `nullopt` indicates that the check is skipped.
+         * This means that all references are allowed.
+         */
+        std::optional<StringSet> allowedReferences;
+
+        /**
+         * env: disallowedReferences
+         *
+         * No needed for `std::optional`, because skipping the check is
+         * the same as disallowing the references.
+         */
+        StringSet disallowedReferences;
+
+        /**
+         * env: allowedRequisites
+         *
+         * See `allowedReferences`
+         */
+        std::optional<StringSet> allowedRequisites;
+
+        /**
+         * env: disallowedRequisites
+         *
+         * See `disallowedReferences`
+         */
+        StringSet disallowedRequisites;
+
+        bool operator==(const OutputChecks &) const = default;
+    };
+
+    /**
+     * Either one set of checks for all outputs, or separate checks
+     * per-output.
+     */
+    std::variant<OutputChecks, std::map<std::string, OutputChecks>> outputChecks = OutputChecks{};
+
+    /**
+     * Whether to avoid scanning for references for a given output.
+     */
+    std::map<std::string, bool> unsafeDiscardReferences;
+
+    /**
+     * In non-structured mode, all bindings specified in the derivation
+     * go directly via the environment, except those listed in the
+     * passAsFile attribute. Those are instead passed as file names
+     * pointing to temporary files containing the contents.
+     *
+     * Note that passAsFile is ignored in structure mode because it's
+     * not needed (attributes are not passed through the environment, so
+     * there is no size constraint).
+     */
+    StringSet passAsFile;
+
+    /**
+     * env: __sandboxProfile
+     *
+     * Just for Darwin
+     */
+    std::string additionalSandboxProfile = "";
+
+    /**
+     * env: __noChroot
+     *
+     * Derivation would like to opt out of the sandbox.
+     *
+     * Builder is free to not respect this wish (because it is
+     * insecure) and fail the build instead.
+     */
+    bool noChroot = false;
+
+    /**
+     * env: __impureHostDeps
+     */
+    StringSet impureHostDeps = {};
+
+    /**
+     * env: impureEnvVars
+     */
+    StringSet impureEnvVars = {};
+
+    /**
+     * env: __darwinAllowLocalNetworking
+     *
+     * Just for Darwin
+     */
+    bool allowLocalNetworking = false;
+
+    /**
+     * env: requiredSystemFeatures
+     */
+    StringSet requiredSystemFeatures = {};
+
+    /**
+     * env: preferLocalBuild
+     */
+    bool preferLocalBuild = false;
+
+    /**
+     * env: allowSubstitutes
+     */
+    bool allowSubstitutes = true;
+
+    bool operator==(const DerivationOptions &) const = default;
+
+    /**
+     * Parse this information from its legacy encoding as part of the
+     * environment. This should not be used with nice greenfield formats
+     * (e.g. JSON) but is necessary for supporing old formats (e.g.
+     * ATerm).
+     */
+    static DerivationOptions fromParsedDerivation(const ParsedDerivation & parsed, bool shouldWarn = true);
+
+    /**
+     * @param drv Must be the same derivation we parsed this from. In
+     * the future we'll flip things around so a `BasicDerivation` has
+     * `DerivationOptions` instead.
+     */
+    StringSet getRequiredSystemFeatures(const BasicDerivation & drv) const;
+
+    /**
+     * @param drv See note on `getRequiredSystemFeatures`
+     */
+    bool canBuildLocally(Store & localStore, const BasicDerivation & drv) const;
+
+    /**
+     * @param drv See note on `getRequiredSystemFeatures`
+     */
+    bool willBuildLocally(Store & localStore, const BasicDerivation & drv) const;
+
+    bool substitutesAllowed() const;
+
+    /**
+     * @param drv See note on `getRequiredSystemFeatures`
+     */
+    bool useUidRange(const BasicDerivation & drv) const;
+};
+
+};
+
+JSON_IMPL(DerivationOptions);
+JSON_IMPL(DerivationOptions::OutputChecks)

src/libstore/meson.build

@@ -197,6 +197,7 @@ sources = files(
   'content-address.cc',
   'daemon.cc',
   'derivations.cc',
+  'derivation-options.cc',
   'derived-path-map.cc',
   'derived-path.cc',
   'downstream-placeholder.cc',
@@ -269,6 +270,7 @@ headers = [config_h] + files(
   'content-address.hh',
   'daemon.hh',
   'derivations.hh',
+  'derivation-options.hh',
   'derived-path-map.hh',
   'derived-path.hh',
   'downstream-placeholder.hh',

src/libstore/misc.cc

@@ -2,6 +2,7 @@
 
 #include "derivations.hh"
 #include "parsed-derivations.hh"
+#include "derivation-options.hh"
 #include "globals.hh"
 #include "store-api.hh"
 #include "thread-pool.hh"
@@ -222,8 +223,9 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
 
             auto drv = make_ref<Derivation>(derivationFromPath(drvPath));
             ParsedDerivation parsedDrv(StorePath(drvPath), *drv);
+            DerivationOptions drvOptions = DerivationOptions::fromParsedDerivation(parsedDrv);
 
-            if (!knownOutputPaths && settings.useSubstitutes && parsedDrv.substitutesAllowed()) {
+            if (!knownOutputPaths && settings.useSubstitutes && drvOptions.substitutesAllowed()) {
                 experimentalFeatureSettings.require(Xp::CaDerivations);
 
                 // If there are unknown output paths, attempt to find if the
@@ -253,7 +255,7 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
                 }
             }
 
-            if (knownOutputPaths && settings.useSubstitutes && parsedDrv.substitutesAllowed()) {
+            if (knownOutputPaths && settings.useSubstitutes && drvOptions.substitutesAllowed()) {
                 auto drvState = make_ref<Sync<DrvState>>(DrvState(invalid.size()));
                 for (auto & output : invalid)
                     pool.enqueue(std::bind(checkOutput, drvPath, drv, output, drvState));

src/libstore/parsed-derivations.cc

@@ -87,47 +87,12 @@ std::optional<Strings> ParsedDerivation::getStringsAttr(const std::string & name
     }
 }
 
-StringSet ParsedDerivation::getRequiredSystemFeatures() const
+std::optional<StringSet> ParsedDerivation::getStringSetAttr(const std::string & name) const
 {
-    // FIXME: cache this?
-    StringSet res;
-    for (auto & i : getStringsAttr("requiredSystemFeatures").value_or(Strings()))
-        res.insert(i);
-    if (!drv.type().hasKnownOutputPaths())
-        res.insert("ca-derivations");
-    return res;
-}
-
-bool ParsedDerivation::canBuildLocally(Store & localStore) const
-{
-    if (drv.platform != settings.thisSystem.get()
-        && !settings.extraPlatforms.get().count(drv.platform)
-        && !drv.isBuiltin())
-        return false;
-
-    if (settings.maxBuildJobs.get() == 0
-        && !drv.isBuiltin())
-        return false;
-
-    for (auto & feature : getRequiredSystemFeatures())
-        if (!localStore.systemFeatures.get().count(feature)) return false;
-
-    return true;
-}
-
-bool ParsedDerivation::willBuildLocally(Store & localStore) const
-{
-    return getBoolAttr("preferLocalBuild") && canBuildLocally(localStore);
-}
-
-bool ParsedDerivation::substitutesAllowed() const
-{
-    return settings.alwaysAllowSubstitutes ? true : getBoolAttr("allowSubstitutes", true);
-}
-
-bool ParsedDerivation::useUidRange() const
-{
-    return getRequiredSystemFeatures().count("uid-range");
+    auto ss = getStringsAttr(name);
+    return ss
+        ? (std::optional{StringSet{ss->begin(), ss->end()}})
+        : (std::optional<StringSet>{});
 }
 
 static std::regex shVarName("[A-Za-z_][A-Za-z0-9_]*");
@@ -188,7 +153,6 @@ static nlohmann::json pathInfoToJSON(
 
 std::optional<nlohmann::json> ParsedDerivation::prepareStructuredAttrs(Store & store, const StorePathSet & inputPaths)
 {
-    auto structuredAttrs = getStructuredAttrs();
     if (!structuredAttrs) return std::nullopt;
 
     auto json = *structuredAttrs;

src/libstore/parsed-derivations.hh

@@ -8,38 +8,40 @@
 
 namespace nix {
 
+struct DerivationOptions;
+
 class ParsedDerivation
 {
     StorePath drvPath;
     BasicDerivation & drv;
     std::unique_ptr<nlohmann::json> structuredAttrs;
 
-public:
-
-    ParsedDerivation(const StorePath & drvPath, BasicDerivation & drv);
-
-    ~ParsedDerivation();
-
-    const nlohmann::json * getStructuredAttrs() const
-    {
-        return structuredAttrs.get();
-    }
-
     std::optional<std::string> getStringAttr(const std::string & name) const;
 
     bool getBoolAttr(const std::string & name, bool def = false) const;
 
     std::optional<Strings> getStringsAttr(const std::string & name) const;
 
-    StringSet getRequiredSystemFeatures() const;
+    std::optional<StringSet> getStringSetAttr(const std::string & name) const;
 
-    bool canBuildLocally(Store & localStore) const;
+    /**
+     * Only `DerivationOptions` is allowed to parse individual fields
+     * from `ParsedDerivation`. This ensure that it includes all
+     * derivation options, and, the likes of `LocalDerivationGoal` are
+     * incapable of more ad-hoc options.
+     */
+    friend struct DerivationOptions;
 
-    bool willBuildLocally(Store & localStore) const;
+public:
 
-    bool substitutesAllowed() const;
+    ParsedDerivation(const StorePath & drvPath, BasicDerivation & drv);
 
-    bool useUidRange() const;
+    ~ParsedDerivation();
+
+    bool hasStructuredAttrs() const
+    {
+        return static_cast<bool>(structuredAttrs);
+    }
 
     std::optional<nlohmann::json> prepareStructuredAttrs(Store & store, const StorePathSet & inputPaths);
 };

src/libstore/unix/build/local-derivation-goal.cc

@@ -184,10 +184,6 @@ void LocalDerivationGoal::killSandbox(bool getStats)
 
 Goal::Co LocalDerivationGoal::tryLocalBuild()
 {
-#if __APPLE__
-    additionalSandboxProfile = parsedDrv->getStringAttr("__sandboxProfile").value_or("");
-#endif
-
     unsigned int curBuilds = worker.getNrLocalBuilds();
     if (curBuilds >= settings.maxBuildJobs) {
         worker.waitForBuildSlot(shared_from_this());
@@ -200,13 +196,12 @@ Goal::Co LocalDerivationGoal::tryLocalBuild()
 
     /* Are we doing a chroot build? */
     {
-        auto noChroot = parsedDrv->getBoolAttr("__noChroot");
         if (settings.sandboxMode == smEnabled) {
-            if (noChroot)
+            if (drvOptions->noChroot)
                 throw Error("derivation '%s' has '__noChroot' set, "
                     "but that's not allowed when 'sandbox' is 'true'", worker.store.printStorePath(drvPath));
 #if __APPLE__
-            if (additionalSandboxProfile != "")
+            if (drvOptions->additionalSandboxProfile != "")
                 throw Error("derivation '%s' specifies a sandbox profile, "
                     "but this is only allowed when 'sandbox' is 'relaxed'", worker.store.printStorePath(drvPath));
 #endif
@@ -215,7 +210,7 @@ Goal::Co LocalDerivationGoal::tryLocalBuild()
         else if (settings.sandboxMode == smDisabled)
             useChroot = false;
         else if (settings.sandboxMode == smRelaxed)
-            useChroot = derivationType->isSandboxed() && !noChroot;
+            useChroot = derivationType->isSandboxed() && !drvOptions->noChroot;
     }
 
     auto & localStore = getLocalStore();
@@ -240,7 +235,7 @@ Goal::Co LocalDerivationGoal::tryLocalBuild()
 
     if (useBuildUsers()) {
         if (!buildUser)
-            buildUser = acquireUserLock(parsedDrv->useUidRange() ? 65536 : 1, useChroot);
+            buildUser = acquireUserLock(drvOptions->useUidRange(*drv) ? 65536 : 1, useChroot);
 
         if (!buildUser) {
             if (!actLock)
@@ -531,14 +526,14 @@ void LocalDerivationGoal::startBuilder()
     killSandbox(false);
 
     /* Right platform? */
-    if (!parsedDrv->canBuildLocally(worker.store)) {
+    if (!drvOptions->canBuildLocally(worker.store, *drv)) {
         // since aarch64-darwin has Rosetta 2, this user can actually run x86_64-darwin on their hardware - we should tell them to run the command to install Darwin 2
         if (drv->platform == "x86_64-darwin" && settings.thisSystem == "aarch64-darwin") {
             throw Error("run `/usr/sbin/softwareupdate --install-rosetta` to enable your %s to run programs for %s", settings.thisSystem, drv->platform);
         } else {
             throw Error("a '%s' with features {%s} is required to build '%s', but I am a '%s' with features {%s}",
                 drv->platform,
-                concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
+                concatStringsSep(", ", drvOptions->getRequiredSystemFeatures(*drv)),
                 worker.store.printStorePath(drvPath),
                 settings.thisSystem,
                 concatStringsSep<StringSet>(", ", worker.store.systemFeatures));
@@ -628,7 +623,7 @@ void LocalDerivationGoal::startBuilder()
     writeStructuredAttrs();
 
     /* Handle exportReferencesGraph(), if set. */
-    if (!parsedDrv->getStructuredAttrs()) {
+    if (!parsedDrv->hasStructuredAttrs()) {
         /* The `exportReferencesGraph' feature allows the references graph
            to be passed to a builder.  This attribute should be a list of
            pairs [name1 path1 name2 path2 ...].  The references graph of
@@ -702,7 +697,7 @@ void LocalDerivationGoal::startBuilder()
         PathSet allowedPaths = settings.allowedImpureHostPrefixes;
 
         /* This works like the above, except on a per-derivation level */
-        auto impurePaths = parsedDrv->getStringsAttr("__impureHostDeps").value_or(Strings());
+        auto impurePaths = drvOptions->impureHostDeps;
 
         for (auto & i : impurePaths) {
             bool found = false;
@@ -722,7 +717,7 @@ void LocalDerivationGoal::startBuilder()
                 throw Error("derivation '%s' requested impure path '%s', but it was not in allowed-impure-host-deps",
                     worker.store.printStorePath(drvPath), i);
 
-            /* Allow files in __impureHostDeps to be missing; e.g.
+            /* Allow files in drvOptions->impureHostDeps to be missing; e.g.
                macOS 11+ has no /usr/lib/libSystem*.dylib */
             pathsInChroot[i] = {i, true};
         }
@@ -762,10 +757,10 @@ void LocalDerivationGoal::startBuilder()
            nobody account.  The latter is kind of a hack to support
            Samba-in-QEMU. */
         createDirs(chrootRootDir + "/etc");
-        if (parsedDrv->useUidRange())
+        if (drvOptions->useUidRange(*drv))
             chownToBuilder(chrootRootDir + "/etc");
 
-        if (parsedDrv->useUidRange() && (!buildUser || buildUser->getUIDCount() < 65536))
+        if (drvOptions->useUidRange(*drv) && (!buildUser || buildUser->getUIDCount() < 65536))
             throw Error("feature 'uid-range' requires the setting '%s' to be enabled", settings.autoAllocateUids.name);
 
         /* Declare the build user's group so that programs get a consistent
@@ -824,7 +819,7 @@ void LocalDerivationGoal::startBuilder()
         }
 
 #else
-        if (parsedDrv->useUidRange())
+        if (drvOptions->useUidRange(*drv))
             throw Error("feature 'uid-range' is not supported on this platform");
         #if __APPLE__
             /* We don't really have any parent prep work to do (yet?)
@@ -834,7 +829,7 @@ void LocalDerivationGoal::startBuilder()
         #endif
 #endif
     } else {
-        if (parsedDrv->useUidRange())
+        if (drvOptions->useUidRange(*drv))
             throw Error("feature 'uid-range' is only supported in sandboxed builds");
     }
 
@@ -879,7 +874,7 @@ void LocalDerivationGoal::startBuilder()
 
     /* Fire up a Nix daemon to process recursive Nix calls from the
        builder. */
-    if (parsedDrv->getRequiredSystemFeatures().count("recursive-nix"))
+    if (drvOptions->getRequiredSystemFeatures(*drv).count("recursive-nix"))
         startDaemon();
 
     /* Run the builder. */
@@ -1147,18 +1142,12 @@ void LocalDerivationGoal::initTmpDir()
     tmpDirInSandbox = tmpDir;
 #endif
 
-    /* In non-structured mode, add all bindings specified in the
-       derivation via the environment, except those listed in the
-       passAsFile attribute. Those are passed as file names pointing
-       to temporary files containing the contents. Note that
-       passAsFile is ignored in structure mode because it's not
-       needed (attributes are not passed through the environment, so
-       there is no size constraint). */
-    if (!parsedDrv->getStructuredAttrs()) {
-
-        StringSet passAsFile = tokenizeString<StringSet>(getOr(drv->env, "passAsFile", ""));
+    /* In non-structured mode, set all bindings either directory in the
+       environment or via a file, as specified by
+       `DerivationOptions::passAsFile`. */
+    if (!parsedDrv->hasStructuredAttrs()) {
         for (auto & i : drv->env) {
-            if (passAsFile.find(i.first) == passAsFile.end()) {
+            if (drvOptions->passAsFile.find(i.first) == drvOptions->passAsFile.end()) {
                 env[i.first] = i.second;
             } else {
                 auto hash = hashString(HashAlgorithm::SHA256, i.first);
@@ -1235,7 +1224,7 @@ void LocalDerivationGoal::initEnv()
         if (!impureEnv.empty())
             experimentalFeatureSettings.require(Xp::ConfigurableImpureEnv);
 
-        for (auto & i : parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings())) {
+        for (auto & i : drvOptions->impureEnvVars){
             auto envVar = impureEnv.find(i);
             if (envVar != impureEnv.end()) {
                 env[i] = envVar->second;
@@ -1995,7 +1984,7 @@ void LocalDerivationGoal::runChild()
             }
 
             /* Make /etc unwritable */
-            if (!parsedDrv->useUidRange())
+            if (!drvOptions->useUidRange(*drv))
                 chmod_(chrootRootDir + "/etc", 0555);
 
             /* Unshare this mount namespace. This is necessary because
@@ -2182,7 +2171,7 @@ void LocalDerivationGoal::runChild()
             }
             sandboxProfile += ")\n";
 
-            sandboxProfile += additionalSandboxProfile;
+            sandboxProfile += drvOptions->additionalSandboxProfile;
         } else
             sandboxProfile +=
                 #include "sandbox-minimal.sb"
@@ -2191,8 +2180,6 @@ void LocalDerivationGoal::runChild()
         debug("Generated sandbox profile:");
         debug(sandboxProfile);
 
-        bool allowLocalNetworking = parsedDrv->getBoolAttr("__darwinAllowLocalNetworking");
-
         /* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms
             to find temporary directories, so we want to open up a broader place for them to put their files, if needed. */
         Path globalTmpDir = canonPath(defaultTempDir(), true);
@@ -2205,7 +2192,7 @@ void LocalDerivationGoal::runChild()
             Strings sandboxArgs;
             sandboxArgs.push_back("_GLOBAL_TMP_DIR");
             sandboxArgs.push_back(globalTmpDir);
-            if (allowLocalNetworking) {
+            if (drvOptions->allowLocalNetworking) {
                 sandboxArgs.push_back("_ALLOW_LOCAL_NETWORKING");
                 sandboxArgs.push_back("1");
             }
@@ -2395,14 +2382,8 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
             inodesSeen);
 
         bool discardReferences = false;
-        if (auto structuredAttrs = parsedDrv->getStructuredAttrs()) {
-            if (auto udr = get(*structuredAttrs, "unsafeDiscardReferences")) {
-                if (auto output = get(*udr, outputName)) {
-                    if (!output->is_boolean())
-                        throw Error("attribute 'unsafeDiscardReferences.\"%s\"' of derivation '%s' must be a Boolean", outputName, drvPath.to_string());
-                    discardReferences = output->get<bool>();
-                }
-            }
+        if (auto udr = get(drvOptions->unsafeDiscardReferences, outputName)) {
+            discardReferences = *udr;
         }
 
         StorePathSet references;
@@ -2873,13 +2854,6 @@ void LocalDerivationGoal::checkOutputs(const std::map<std::string, ValidPathInfo
         auto & outputName = output.first;
         auto & info = output.second;
 
-        struct Checks
-        {
-            bool ignoreSelfRefs = false;
-            std::optional<uint64_t> maxSize, maxClosureSize;
-            std::optional<Strings> allowedReferences, allowedRequisites, disallowedReferences, disallowedRequisites;
-        };
-
         /* Compute the closure and closure size of some output. This
            is slightly tricky because some of its references (namely
            other outputs) may not be valid yet. */
@@ -2911,7 +2885,7 @@ void LocalDerivationGoal::checkOutputs(const std::map<std::string, ValidPathInfo
             return std::make_pair(std::move(pathsDone), closureSize);
         };
 
-        auto applyChecks = [&](const Checks & checks)
+        auto applyChecks = [&](const DerivationOptions::OutputChecks & checks)
         {
             if (checks.maxSize && info.narSize > *checks.maxSize)
                 throw BuildError("path '%s' is too large at %d bytes; limit is %d bytes",
@@ -2924,15 +2898,13 @@ void LocalDerivationGoal::checkOutputs(const std::map<std::string, ValidPathInfo
                         worker.store.printStorePath(info.path), closureSize, *checks.maxClosureSize);
             }
 
-            auto checkRefs = [&](const std::optional<Strings> & value, bool allowed, bool recursive)
+            auto checkRefs = [&](const StringSet & value, bool allowed, bool recursive)
             {
-                if (!value) return;
-
                 /* Parse a list of reference specifiers.  Each element must
                    either be a store path, or the symbolic name of the output
                    of the derivation (such as `out'). */
                 StorePathSet spec;
-                for (auto & i : *value) {
+                for (auto & i : value) {
                     if (worker.store.isStorePath(i))
                         spec.insert(worker.store.parseStorePath(i));
                     else if (auto output = get(outputs, i))
@@ -2970,73 +2942,35 @@ void LocalDerivationGoal::checkOutputs(const std::map<std::string, ValidPathInfo
                 }
             };
 
-            checkRefs(checks.allowedReferences, true, false);
-            checkRefs(checks.allowedRequisites, true, true);
-            checkRefs(checks.disallowedReferences, false, false);
-            checkRefs(checks.disallowedRequisites, false, true);
+            /* Mandatory check: absent whitelist, and present but empty
+               whitelist mean very different things. */
+            if (auto & refs = checks.allowedReferences) {
+                checkRefs(*refs, true, false);
+            }
+            if (auto & refs = checks.allowedRequisites) {
+                checkRefs(*refs, true, true);
+            }
+
+            /* Optimization: don't need to do anything when
+               disallowed and empty set. */
+            if (!checks.disallowedReferences.empty()) {
+                checkRefs(checks.disallowedReferences, false, false);
+            }
+            if (!checks.disallowedRequisites.empty()) {
+                checkRefs(checks.disallowedRequisites, false, true);
+            }
         };
 
-        if (auto structuredAttrs = parsedDrv->getStructuredAttrs()) {
-            if (get(*structuredAttrs, "allowedReferences")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'allowedReferences'; use 'outputChecks' instead");
-            }
-            if (get(*structuredAttrs, "allowedRequisites")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'allowedRequisites'; use 'outputChecks' instead");
-            }
-            if (get(*structuredAttrs, "disallowedRequisites")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'disallowedRequisites'; use 'outputChecks' instead");
-            }
-            if (get(*structuredAttrs, "disallowedReferences")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'disallowedReferences'; use 'outputChecks' instead");
-            }
-            if (get(*structuredAttrs, "maxSize")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'maxSize'; use 'outputChecks' instead");
-            }
-            if (get(*structuredAttrs, "maxClosureSize")){
-                warn("'structuredAttrs' disables the effect of the top-level attribute 'maxClosureSize'; use 'outputChecks' instead");
-            }
-            if (auto outputChecks = get(*structuredAttrs, "outputChecks")) {
-                if (auto output = get(*outputChecks, outputName)) {
-                    Checks checks;
+        std::visit(overloaded{
+            [&](const DerivationOptions::OutputChecks & checks) {
+                applyChecks(checks);
+            },
+            [&](const std::map<std::string, DerivationOptions::OutputChecks> & checksPerOutput) {
+                if (auto outputChecks = get(checksPerOutput, outputName))
 
-                    if (auto maxSize = get(*output, "maxSize"))
-                        checks.maxSize = maxSize->get<uint64_t>();
-
-                    if (auto maxClosureSize = get(*output, "maxClosureSize"))
-                        checks.maxClosureSize = maxClosureSize->get<uint64_t>();
-
-                    auto get_ = [&](const std::string & name) -> std::optional<Strings> {
-                        if (auto i = get(*output, name)) {
-                            Strings res;
-                            for (auto j = i->begin(); j != i->end(); ++j) {
-                                if (!j->is_string())
-                                    throw Error("attribute '%s' of derivation '%s' must be a list of strings", name, worker.store.printStorePath(drvPath));
-                                res.push_back(j->get<std::string>());
-                            }
-                            checks.disallowedRequisites = res;
-                            return res;
-                        }
-                        return {};
-                    };
-
-                    checks.allowedReferences = get_("allowedReferences");
-                    checks.allowedRequisites = get_("allowedRequisites");
-                    checks.disallowedReferences = get_("disallowedReferences");
-                    checks.disallowedRequisites = get_("disallowedRequisites");
-
-                    applyChecks(checks);
-                }
-            }
-        } else {
-            // legacy non-structured-attributes case
-            Checks checks;
-            checks.ignoreSelfRefs = true;
-            checks.allowedReferences = parsedDrv->getStringsAttr("allowedReferences");
-            checks.allowedRequisites = parsedDrv->getStringsAttr("allowedRequisites");
-            checks.disallowedReferences = parsedDrv->getStringsAttr("disallowedReferences");
-            checks.disallowedRequisites = parsedDrv->getStringsAttr("disallowedRequisites");
-            applyChecks(checks);
-        }
+                    applyChecks(*outputChecks);
+            },
+        }, drvOptions->outputChecks);
     }
 }
 

src/libstore/unix/build/local-derivation-goal.hh

@@ -109,11 +109,6 @@ struct LocalDerivationGoal : public DerivationGoal
     typedef map<std::string, std::string> Environment;
     Environment env;
 
-#if __APPLE__
-    typedef std::string SandboxProfile;
-    SandboxProfile additionalSandboxProfile;
-#endif
-
     /**
      * Hash rewriting.
      */

src/libutil/json-utils.cc

@@ -3,6 +3,7 @@
 #include "types.hh"
 #include <nlohmann/json_fwd.hpp>
 #include <iostream>
+#include <optional>
 
 namespace nix {
 
@@ -38,6 +39,15 @@ std::optional<nlohmann::json> optionalValueAt(const nlohmann::json::object_t & m
     return std::optional { map.at(key) };
 }
 
+std::optional<nlohmann::json> nullableValueAt(const nlohmann::json::object_t & map, const std::string & key)
+{
+    auto value = valueAt(map, key);
+
+    if (value.is_null())
+        return std::nullopt;
+
+    return std::optional { std::move(value) };
+}
 
 const nlohmann::json * getNullable(const nlohmann::json & value)
 {

src/libutil/json-utils.hh

@@ -25,6 +25,7 @@ const nlohmann::json & valueAt(
     const std::string & key);
 
 std::optional<nlohmann::json> optionalValueAt(const nlohmann::json::object_t & value, const std::string & key);
+std::optional<nlohmann::json> nullableValueAt(const nlohmann::json::object_t & value, const std::string & key);
 
 /**
  * Downcast the json object, failing with a nice error if the conversion fails.
@@ -69,6 +70,9 @@ struct json_avoids_null<std::vector<T>> : std::true_type {};
 template<typename T>
 struct json_avoids_null<std::list<T>> : std::true_type {};
 
+template<typename T>
+struct json_avoids_null<std::set<T>> : std::true_type {};
+
 template<typename K, typename V>
 struct json_avoids_null<std::map<K, V>> : std::true_type {};
 

src/nix-build/nix-build.cc

@@ -11,6 +11,7 @@
 
 #include "current-process.hh"
 #include "parsed-derivations.hh"
+#include "derivation-options.hh"
 #include "store-api.hh"
 #include "local-fs-store.hh"
 #include "globals.hh"
@@ -542,12 +543,13 @@ static void main_nix_build(int argc, char * * argv)
         env["NIX_STORE"] = store->storeDir;
         env["NIX_BUILD_CORES"] = std::to_string(settings.buildCores);
 
-        auto passAsFile = tokenizeString<StringSet>(getOr(drv.env, "passAsFile", ""));
+        ParsedDerivation parsedDrv(packageInfo.requireDrvPath(), drv);
+        DerivationOptions drvOptions = DerivationOptions::fromParsedDerivation(parsedDrv);
 
         int fileNr = 0;
 
         for (auto & var : drv.env)
-            if (passAsFile.count(var.first)) {
+            if (drvOptions.passAsFile.count(var.first)) {
                 auto fn = ".attr-" + std::to_string(fileNr++);
                 Path p = (tmpDir.path() / fn).string();
                 writeFile(p, var.second);
@@ -557,7 +559,7 @@ static void main_nix_build(int argc, char * * argv)
 
         std::string structuredAttrsRC;
 
-        if (env.count("__json")) {
+        if (parsedDrv.hasStructuredAttrs()) {
             StorePathSet inputs;
 
             std::function<void(const StorePath &, const DerivedPathMap<StringSet>::ChildNode &)> accumInputClosure;
@@ -575,8 +577,6 @@ static void main_nix_build(int argc, char * * argv)
             for (const auto & [inputDrv, inputNode] : drv.inputDrvs.map)
                 accumInputClosure(inputDrv, inputNode);
 
-            ParsedDerivation parsedDrv(packageInfo.requireDrvPath(), drv);
-
             if (auto structAttrs = parsedDrv.prepareStructuredAttrs(*store, inputs)) {
                 auto json = structAttrs.value();
                 structuredAttrsRC = writeStructuredAttrsShell(json);