Merge branch 'master' into read-only-local-store

src/libcmd/installables.cc

@@ -701,7 +701,7 @@ RawInstallablesCommand::RawInstallablesCommand()
 {
     addFlag({
         .longName = "stdin",
-        .description = "Read installables from the standard input.",
+        .description = "Read installables from the standard input. No default installable applied.",
         .handler = {&readFromStdIn, true}
     });
 
@@ -730,9 +730,9 @@ void RawInstallablesCommand::run(ref<Store> store)
         while (std::cin >> word) {
             rawInstallables.emplace_back(std::move(word));
         }
+    } else {
+        applyDefaultInstallables(rawInstallables);
     }
-
-    applyDefaultInstallables(rawInstallables);
     run(store, std::move(rawInstallables));
 }
 

src/libexpr/eval.hh

@@ -741,7 +741,7 @@ struct EvalSettings : Config
           If set to `true`, the Nix evaluator will not allow access to any
           files outside of the Nix search path (as set via the `NIX_PATH`
           environment variable or the `-I` option), or to URIs outside of
-          `allowed-uri`. The default is `false`.
+          `allowed-uris`. The default is `false`.
         )"};
 
     Setting<bool> pureEval{this, false, "pure-eval",

src/libexpr/primops.cc

@@ -6,7 +6,7 @@
 #include "globals.hh"
 #include "json-to-value.hh"
 #include "names.hh"
-#include "references.hh"
+#include "path-references.hh"
 #include "store-api.hh"
 #include "util.hh"
 #include "value-to-json.hh"
@@ -4058,18 +4058,6 @@ static RegisterPrimOp primop_splitVersion({
 RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
 
 
-RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun)
-{
-    if (!primOps) primOps = new PrimOps;
-    primOps->push_back({
-        .name = name,
-        .args = {},
-        .arity = arity,
-        .fun = fun,
-    });
-}
-
-
 RegisterPrimOp::RegisterPrimOp(Info && info)
 {
     if (!primOps) primOps = new PrimOps;

src/libexpr/primops.hh

@@ -28,11 +28,6 @@ struct RegisterPrimOp
      * will get called during EvalState initialization, so there
      * may be primops not yet added and builtins is not yet sorted.
      */
-    RegisterPrimOp(
-        std::string name,
-        size_t arity,
-        PrimOpFun fun);
-
     RegisterPrimOp(Info && info);
 };
 

src/libexpr/primops/context.cc

@@ -12,7 +12,11 @@ static void prim_unsafeDiscardStringContext(EvalState & state, const PosIdx pos,
     v.mkString(*s);
 }
 
-static RegisterPrimOp primop_unsafeDiscardStringContext("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
+static RegisterPrimOp primop_unsafeDiscardStringContext({
+    .name = "__unsafeDiscardStringContext",
+    .arity = 1,
+    .fun = prim_unsafeDiscardStringContext
+});
 
 
 static void prim_hasContext(EvalState & state, const PosIdx pos, Value * * args, Value & v)
@@ -22,7 +26,16 @@ static void prim_hasContext(EvalState & state, const PosIdx pos, Value * * args,
     v.mkBool(!context.empty());
 }
 
-static RegisterPrimOp primop_hasContext("__hasContext", 1, prim_hasContext);
+static RegisterPrimOp primop_hasContext({
+    .name = "__hasContext",
+    .args = {"s"},
+    .doc = R"(
+      Return `true` if string *s* has a non-empty context. The
+      context can be obtained with
+      [`getContext`](#builtins-getContext).
+    )",
+    .fun = prim_hasContext
+});
 
 
 /* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
@@ -51,7 +64,11 @@ static void prim_unsafeDiscardOutputDependency(EvalState & state, const PosIdx p
     v.mkString(*s, context2);
 }
 
-static RegisterPrimOp primop_unsafeDiscardOutputDependency("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
+static RegisterPrimOp primop_unsafeDiscardOutputDependency({
+    .name = "__unsafeDiscardOutputDependency",
+    .arity = 1,
+    .fun = prim_unsafeDiscardOutputDependency
+});
 
 
 /* Extract the context of a string as a structured Nix value.
@@ -119,7 +136,30 @@ static void prim_getContext(EvalState & state, const PosIdx pos, Value * * args,
     v.mkAttrs(attrs);
 }
 
-static RegisterPrimOp primop_getContext("__getContext", 1, prim_getContext);
+static RegisterPrimOp primop_getContext({
+    .name = "__getContext",
+    .args = {"s"},
+    .doc = R"(
+      Return the string context of *s*.
+
+      The string context tracks references to derivations within a string.
+      It is represented as an attribute set of [store derivation](@docroot@/glossary.md#gloss-store-derivation) paths mapping to output names.
+
+      Using [string interpolation](@docroot@/language/string-interpolation.md) on a derivation will add that derivation to the string context.
+      For example,
+
+      ```nix
+      builtins.getContext "${derivation { name = "a"; builder = "b"; system = "c"; }}"
+      ```
+
+      evaluates to
+
+      ```
+      { "/nix/store/arhvjaf6zmlyn8vh8fgn55rpwnxq0n7l-a.drv" = { outputs = [ "out" ]; }; }
+      ```
+    )",
+    .fun = prim_getContext
+});
 
 
 /* Append the given context to a given string.
@@ -192,6 +232,10 @@ static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * ar
     v.mkString(orig, context);
 }
 
-static RegisterPrimOp primop_appendContext("__appendContext", 2, prim_appendContext);
+static RegisterPrimOp primop_appendContext({
+    .name = "__appendContext",
+    .arity = 2,
+    .fun = prim_appendContext
+});
 
 }

src/libexpr/primops/fetchMercurial.cc

@@ -88,6 +88,10 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
     state.allowPath(tree.storePath);
 }
 
-static RegisterPrimOp r_fetchMercurial("fetchMercurial", 1, prim_fetchMercurial);
+static RegisterPrimOp r_fetchMercurial({
+    .name = "fetchMercurial",
+    .arity = 1,
+    .fun = prim_fetchMercurial
+});
 
 }

src/libexpr/primops/fetchTree.cc

@@ -194,7 +194,11 @@ static void prim_fetchTree(EvalState & state, const PosIdx pos, Value * * args,
 }
 
 // FIXME: document
-static RegisterPrimOp primop_fetchTree("fetchTree", 1, prim_fetchTree);
+static RegisterPrimOp primop_fetchTree({
+    .name = "fetchTree",
+    .arity = 1,
+    .fun = prim_fetchTree
+});
 
 static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v,
     const std::string & who, bool unpack, std::string name)

src/libexpr/primops/fromTOML.cc

@@ -3,6 +3,8 @@
 
 #include "../../toml11/toml.hpp"
 
+#include <sstream>
+
 namespace nix {
 
 static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, Value & val)
@@ -58,8 +60,18 @@ static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, V
             case toml::value_t::offset_datetime:
             case toml::value_t::local_date:
             case toml::value_t::local_time:
-                // We fail since Nix doesn't have date and time types
-                throw std::runtime_error("Dates and times are not supported");
+                {
+                    if (experimentalFeatureSettings.isEnabled(Xp::ParseTomlTimestamps)) {
+                        auto attrs = state.buildBindings(2);
+                        attrs.alloc("_type").mkString("timestamp");
+                        std::ostringstream s;
+                        s << t;
+                        attrs.alloc("value").mkString(s.str());
+                        v.mkAttrs(attrs);
+                    } else {
+                        throw std::runtime_error("Dates and times are not supported");
+                    }
+                }
                 break;;
             case toml::value_t::empty:
                 v.mkNull();
@@ -78,6 +90,24 @@ static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, V
     }
 }
 
-static RegisterPrimOp primop_fromTOML("fromTOML", 1, prim_fromTOML);
+static RegisterPrimOp primop_fromTOML({
+    .name = "fromTOML",
+    .args = {"e"},
+    .doc = R"(
+      Convert a TOML string to a Nix value. For example,
+
+      ```nix
+      builtins.fromTOML ''
+        x=1
+        s="a"
+        [table]
+        y=2
+      ''
+      ```
+
+      returns the value `{ s = "a"; table = { y = 2; }; x = 1; }`.
+    )",
+    .fun = prim_fromTOML
+});
 
 }

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

@@ -4,7 +4,7 @@
 #include "worker.hh"
 #include "builtins.hh"
 #include "builtins/buildenv.hh"
-#include "references.hh"
+#include "path-references.hh"
 #include "finally.hh"
 #include "util.hh"
 #include "archive.hh"
@@ -1457,7 +1457,7 @@ void LocalDerivationGoal::startDaemon()
                 (struct sockaddr *) &remoteAddr, &remoteAddrLen);
             if (!remote) {
                 if (errno == EINTR || errno == EAGAIN) continue;
-                if (errno == EINVAL) break;
+                if (errno == EINVAL || errno == ECONNABORTED) break;
                 throw SysError("accepting connection");
             }
 
@@ -1487,8 +1487,22 @@ void LocalDerivationGoal::startDaemon()
 
 void LocalDerivationGoal::stopDaemon()
 {
-    if (daemonSocket && shutdown(daemonSocket.get(), SHUT_RDWR) == -1)
-        throw SysError("shutting down daemon socket");
+    if (daemonSocket && shutdown(daemonSocket.get(), SHUT_RDWR) == -1) {
+        // According to the POSIX standard, the 'shutdown' function should
+        // return an ENOTCONN error when attempting to shut down a socket that
+        // hasn't been connected yet. This situation occurs when the 'accept'
+        // function is called on a socket without any accepted connections,
+        // leaving the socket unconnected. While Linux doesn't seem to produce
+        // an error for sockets that have only been accepted, more
+        // POSIX-compliant operating systems like OpenBSD, macOS, and others do
+        // return the ENOTCONN error. Therefore, we handle this error here to
+        // avoid raising an exception for compliant behaviour.
+        if (errno == ENOTCONN) {
+            daemonSocket.close();
+        } else {
+            throw SysError("shutting down daemon socket");
+        }
+    }
 
     if (daemonThread.joinable())
         daemonThread.join();
@@ -1499,7 +1513,8 @@ void LocalDerivationGoal::stopDaemon()
         thread.join();
     daemonWorkerThreads.clear();
 
-    daemonSocket = -1;
+    // release the socket.
+    daemonSocket.close();
 }
 
 
@@ -2379,18 +2394,21 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
             continue;
         auto references = *referencesOpt;
 
-        auto rewriteOutput = [&]() {
+        auto rewriteOutput = [&](const StringMap & rewrites) {
             /* Apply hash rewriting if necessary. */
-            if (!outputRewrites.empty()) {
+            if (!rewrites.empty()) {
                 debug("rewriting hashes in '%1%'; cross fingers", actualPath);
 
-                /* FIXME: this is in-memory. */
-                StringSink sink;
-                dumpPath(actualPath, sink);
+                /* FIXME: Is this actually streaming? */
+                auto source = sinkToSource([&](Sink & nextSink) {
+                    RewritingSink rsink(rewrites, nextSink);
+                    dumpPath(actualPath, rsink);
+                    rsink.flush();
+                });
+                Path tmpPath = actualPath + ".tmp";
+                restorePath(tmpPath, *source);
                 deletePath(actualPath);
-                sink.s = rewriteStrings(sink.s, outputRewrites);
-                StringSource source(sink.s);
-                restorePath(actualPath, source);
+                movePath(tmpPath, actualPath);
 
                 /* FIXME: set proper permissions in restorePath() so
                    we don't have to do another traversal. */
@@ -2439,7 +2457,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                         "since recursive hashing is not enabled (one of outputHashMode={flat,text} is true)",
                         actualPath);
             }
-            rewriteOutput();
+            rewriteOutput(outputRewrites);
             /* FIXME optimize and deduplicate with addToStore */
             std::string oldHashPart { scratchPath->hashPart() };
             HashModuloSink caSink { outputHash.hashType, oldHashPart };
@@ -2477,16 +2495,14 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                 Hash::dummy,
             };
             if (*scratchPath != newInfo0.path) {
-                // Also rewrite the output path
-                auto source = sinkToSource([&](Sink & nextSink) {
-                    RewritingSink rsink2(oldHashPart, std::string(newInfo0.path.hashPart()), nextSink);
-                    dumpPath(actualPath, rsink2);
-                    rsink2.flush();
-                });
-                Path tmpPath = actualPath + ".tmp";
-                restorePath(tmpPath, *source);
-                deletePath(actualPath);
-                movePath(tmpPath, actualPath);
+                // If the path has some self-references, we need to rewrite
+                // them.
+                // (note that this doesn't invalidate the ca hash we calculated
+                // above because it's computed *modulo the self-references*, so
+                // it already takes this rewrite into account).
+                rewriteOutput(
+                    StringMap{{oldHashPart,
+                               std::string(newInfo0.path.hashPart())}});
             }
 
             HashResult narHashAndSize = hashPath(htSHA256, actualPath);
@@ -2508,7 +2524,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                     outputRewrites.insert_or_assign(
                         std::string { scratchPath->hashPart() },
                         std::string { requiredFinalPath.hashPart() });
-                rewriteOutput();
+                rewriteOutput(outputRewrites);
                 auto narHashAndSize = hashPath(htSHA256, actualPath);
                 ValidPathInfo newInfo0 { requiredFinalPath, narHashAndSize.first };
                 newInfo0.narSize = narHashAndSize.second;

src/libstore/build/personality.cc

@@ -21,7 +21,8 @@ void setPersonality(std::string_view system)
                 && (std::string_view(SYSTEM) == "x86_64-linux"
                     || (!strcmp(utsbuf.sysname, "Linux") && !strcmp(utsbuf.machine, "x86_64"))))
             || system == "armv7l-linux"
-            || system == "armv6l-linux")
+            || system == "armv6l-linux"
+            || system == "armv5tel-linux")
         {
             if (personality(PER_LINUX32) == -1)
                 throw SysError("cannot set 32-bit personality");

src/libstore/globals.hh

@@ -691,20 +691,19 @@ public:
         Strings{"https://cache.nixos.org/"},
         "substituters",
         R"(
-          A list of [URLs of Nix stores](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format)
-          to be used as substituters, separated by whitespace.
-          Substituters are tried based on their Priority value, which each substituter can set
-          independently. Lower value means higher priority.
-          The default is `https://cache.nixos.org`, with a Priority of 40.
+          A list of [URLs of Nix stores](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format) to be used as substituters, separated by whitespace.
+          A substituter is an additional [store]{@docroot@/glossary.md##gloss-store} from which Nix can obtain [store objects](@docroot@/glossary.md#gloss-store-object) instead of building them.
 
-          At least one of the following conditions must be met for Nix to use
-          a substituter:
+          Substituters are tried based on their priority value, which each substituter can set independently.
+          Lower value means higher priority.
+          The default is `https://cache.nixos.org`, which has a priority of 40.
+
+          At least one of the following conditions must be met for Nix to use a substituter:
 
           - the substituter is in the [`trusted-substituters`](#conf-trusted-substituters) list
           - the user calling Nix is in the [`trusted-users`](#conf-trusted-users) list
 
-          In addition, each store path should be trusted as described
-          in [`trusted-public-keys`](#conf-trusted-public-keys)
+          In addition, each store path should be trusted as described in [`trusted-public-keys`](#conf-trusted-public-keys)
         )",
         {"binary-caches"}};
 
@@ -896,12 +895,11 @@ public:
         this, {}, "hashed-mirrors",
         R"(
           A list of web servers used by `builtins.fetchurl` to obtain files by
-          hash. The default is `http://tarballs.nixos.org/`. Given a hash type
-          *ht* and a base-16 hash *h*, Nix will try to download the file from
-          *hashed-mirror*/*ht*/*h*. This allows files to be downloaded even if
-          they have disappeared from their original URI. For example, given
-          the default mirror `http://tarballs.nixos.org/`, when building the
-          derivation
+          hash. Given a hash type *ht* and a base-16 hash *h*, Nix will try to
+          download the file from *hashed-mirror*/*ht*/*h*. This allows files to
+          be downloaded even if they have disappeared from their original URI.
+          For example, given an example mirror `http://tarballs.nixos.org/`,
+          when building the derivation
 
           ```nix
           builtins.fetchurl {

src/libstore/path-references.cc

@@ -0,0 +1,73 @@
+#include "path-references.hh"
+#include "hash.hh"
+#include "util.hh"
+#include "archive.hh"
+
+#include <map>
+#include <cstdlib>
+#include <mutex>
+#include <algorithm>
+
+
+namespace nix {
+
+
+PathRefScanSink::PathRefScanSink(StringSet && hashes, std::map<std::string, StorePath> && backMap)
+    : RefScanSink(std::move(hashes))
+    , backMap(std::move(backMap))
+{ }
+
+PathRefScanSink PathRefScanSink::fromPaths(const StorePathSet & refs)
+{
+    StringSet hashes;
+    std::map<std::string, StorePath> backMap;
+
+    for (auto & i : refs) {
+        std::string hashPart(i.hashPart());
+        auto inserted = backMap.emplace(hashPart, i).second;
+        assert(inserted);
+        hashes.insert(hashPart);
+    }
+
+    return PathRefScanSink(std::move(hashes), std::move(backMap));
+}
+
+StorePathSet PathRefScanSink::getResultPaths()
+{
+    /* Map the hashes found back to their store paths. */
+    StorePathSet found;
+    for (auto & i : getResult()) {
+        auto j = backMap.find(i);
+        assert(j != backMap.end());
+        found.insert(j->second);
+    }
+
+    return found;
+}
+
+
+std::pair<StorePathSet, HashResult> scanForReferences(
+    const std::string & path,
+    const StorePathSet & refs)
+{
+    HashSink hashSink { htSHA256 };
+    auto found = scanForReferences(hashSink, path, refs);
+    auto hash = hashSink.finish();
+    return std::pair<StorePathSet, HashResult>(found, hash);
+}
+
+StorePathSet scanForReferences(
+    Sink & toTee,
+    const Path & path,
+    const StorePathSet & refs)
+{
+    PathRefScanSink refsSink = PathRefScanSink::fromPaths(refs);
+    TeeSink sink { refsSink, toTee };
+
+    /* Look for the hashes in the NAR dump of the path. */
+    dumpPath(path, sink);
+
+    return refsSink.getResultPaths();
+}
+
+}

src/libstore/path-references.hh

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "references.hh"
+#include "path.hh"
+
+namespace nix {
+
+std::pair<StorePathSet, HashResult> scanForReferences(const Path & path, const StorePathSet & refs);
+
+StorePathSet scanForReferences(Sink & toTee, const Path & path, const StorePathSet & refs);
+
+class PathRefScanSink : public RefScanSink
+{
+    std::map<std::string, StorePath> backMap;
+
+    PathRefScanSink(StringSet && hashes, std::map<std::string, StorePath> && backMap);
+
+public:
+
+    static PathRefScanSink fromPaths(const StorePathSet & refs);
+
+    StorePathSet getResultPaths();
+};
+
+}

src/libstore/uds-remote-store.cc

@@ -13,6 +13,14 @@
 
 namespace nix {
 
+std::string UDSRemoteStoreConfig::doc()
+{
+    return
+        #include "uds-remote-store.md"
+        ;
+}
+
+
 UDSRemoteStore::UDSRemoteStore(const Params & params)
     : StoreConfig(params)
     , LocalFSStoreConfig(params)

src/libstore/uds-remote-store.hh

@@ -17,12 +17,7 @@ struct UDSRemoteStoreConfig : virtual LocalFSStoreConfig, virtual RemoteStoreCon
 
     const std::string name() override { return "Local Daemon Store"; }
 
-    std::string doc() override
-    {
-        return
-          #include "uds-remote-store.md"
-          ;
-    }
+    std::string doc() override;
 };
 
 class UDSRemoteStore : public virtual UDSRemoteStoreConfig, public virtual LocalFSStore, public virtual RemoteStore

src/libutil/experimental-features.cc

@@ -12,7 +12,7 @@ struct ExperimentalFeatureDetails
     std::string_view description;
 };
 
-constexpr std::array<ExperimentalFeatureDetails, 14> xpFeatureDetails = {{
+constexpr std::array<ExperimentalFeatureDetails, 15> xpFeatureDetails = {{
     {
         .tag = Xp::CaDerivations,
         .name = "ca-derivations",
@@ -214,6 +214,13 @@ constexpr std::array<ExperimentalFeatureDetails, 14> xpFeatureDetails = {{
                 derivations that are themselves derivations outputs.
         )",
     },
+    {
+        .tag = Xp::ParseTomlTimestamps,
+        .name = "parse-toml-timestamps",
+        .description = R"(
+            Allow parsing of timestamps in builtins.fromTOML.
+        )",
+    },
     {
         .tag = Xp::ReadOnlyLocalStore,
         .name = "read-only-local-store",
@@ -263,7 +270,7 @@ std::string_view showExperimentalFeature(const ExperimentalFeature tag)
     return xpFeatureDetails[(size_t)tag].name;
 }
 
-nlohmann::json documentExperimentalFeatures() 
+nlohmann::json documentExperimentalFeatures()
 {
     StringMap res;
     for (auto & xpFeature : xpFeatureDetails)

src/libutil/experimental-features.hh

@@ -30,6 +30,7 @@ enum struct ExperimentalFeature
     DiscardReferences,
     DaemonTrustOverride,
     DynamicDerivations,
+    ParseTomlTimestamps,
     ReadOnlyLocalStore,
 };
 

src/libutil/filesystem.cc

@@ -63,30 +63,19 @@ std::pair<AutoCloseFD, Path> createTempFile(const Path & prefix)
     return {std::move(fd), tmpl};
 }
 
-void createSymlink(const Path & target, const Path & link,
-    std::optional<time_t> mtime)
+void createSymlink(const Path & target, const Path & link)
 {
     if (symlink(target.c_str(), link.c_str()))
         throw SysError("creating symlink from '%1%' to '%2%'", link, target);
-    if (mtime) {
-        struct timeval times[2];
-        times[0].tv_sec = *mtime;
-        times[0].tv_usec = 0;
-        times[1].tv_sec = *mtime;
-        times[1].tv_usec = 0;
-        if (lutimes(link.c_str(), times))
-            throw SysError("setting time of symlink '%s'", link);
-    }
 }
 
-void replaceSymlink(const Path & target, const Path & link,
-    std::optional<time_t> mtime)
+void replaceSymlink(const Path & target, const Path & link)
 {
     for (unsigned int n = 0; true; n++) {
         Path tmp = canonPath(fmt("%s/.%d_%s", dirOf(link), n, baseNameOf(link)));
 
         try {
-            createSymlink(target, tmp, mtime);
+            createSymlink(target, tmp);
         } catch (SysError & e) {
             if (e.errNo == EEXIST) continue;
             throw;

src/libutil/references.cc

@@ -6,6 +6,7 @@
 #include <map>
 #include <cstdlib>
 #include <mutex>
+#include <algorithm>
 
 
 namespace nix {
@@ -66,69 +67,20 @@ void RefScanSink::operator () (std::string_view data)
 }
 
 
-PathRefScanSink::PathRefScanSink(StringSet && hashes, std::map<std::string, StorePath> && backMap)
-    : RefScanSink(std::move(hashes))
-    , backMap(std::move(backMap))
-{ }
-
-PathRefScanSink PathRefScanSink::fromPaths(const StorePathSet & refs)
-{
-    StringSet hashes;
-    std::map<std::string, StorePath> backMap;
-
-    for (auto & i : refs) {
-        std::string hashPart(i.hashPart());
-        auto inserted = backMap.emplace(hashPart, i).second;
-        assert(inserted);
-        hashes.insert(hashPart);
-    }
-
-    return PathRefScanSink(std::move(hashes), std::move(backMap));
-}
-
-StorePathSet PathRefScanSink::getResultPaths()
-{
-    /* Map the hashes found back to their store paths. */
-    StorePathSet found;
-    for (auto & i : getResult()) {
-        auto j = backMap.find(i);
-        assert(j != backMap.end());
-        found.insert(j->second);
-    }
-
-    return found;
-}
-
-
-std::pair<StorePathSet, HashResult> scanForReferences(
-    const std::string & path,
-    const StorePathSet & refs)
-{
-    HashSink hashSink { htSHA256 };
-    auto found = scanForReferences(hashSink, path, refs);
-    auto hash = hashSink.finish();
-    return std::pair<StorePathSet, HashResult>(found, hash);
-}
-
-StorePathSet scanForReferences(
-    Sink & toTee,
-    const Path & path,
-    const StorePathSet & refs)
-{
-    PathRefScanSink refsSink = PathRefScanSink::fromPaths(refs);
-    TeeSink sink { refsSink, toTee };
-
-    /* Look for the hashes in the NAR dump of the path. */
-    dumpPath(path, sink);
-
-    return refsSink.getResultPaths();
-}
-
-
 RewritingSink::RewritingSink(const std::string & from, const std::string & to, Sink & nextSink)
-    : from(from), to(to), nextSink(nextSink)
+    : RewritingSink({{from, to}}, nextSink)
 {
-    assert(from.size() == to.size());
+}
+
+RewritingSink::RewritingSink(const StringMap & rewrites, Sink & nextSink)
+    : rewrites(rewrites), nextSink(nextSink)
+{
+    long unsigned int maxRewriteSize = 0;
+    for (auto & [from, to] : rewrites) {
+        assert(from.size() == to.size());
+        maxRewriteSize = std::max(maxRewriteSize, from.size());
+    }
+    this->maxRewriteSize = maxRewriteSize;
 }
 
 void RewritingSink::operator () (std::string_view data)
@@ -136,13 +88,13 @@ void RewritingSink::operator () (std::string_view data)
     std::string s(prev);
     s.append(data);
 
-    size_t j = 0;
-    while ((j = s.find(from, j)) != std::string::npos) {
-        matches.push_back(pos + j);
-        s.replace(j, from.size(), to);
-    }
+    s = rewriteStrings(s, rewrites);
 
-    prev = s.size() < from.size() ? s : std::string(s, s.size() - from.size() + 1, from.size() - 1);
+    prev = s.size() < maxRewriteSize
+        ? s
+        : maxRewriteSize == 0
+            ? ""
+            : std::string(s, s.size() - maxRewriteSize + 1, maxRewriteSize - 1);
 
     auto consumed = s.size() - prev.size();
 

src/libutil/references.hh

@@ -2,14 +2,9 @@
 ///@file
 
 #include "hash.hh"
-#include "path.hh"
 
 namespace nix {
 
-std::pair<StorePathSet, HashResult> scanForReferences(const Path & path, const StorePathSet & refs);
-
-StorePathSet scanForReferences(Sink & toTee, const Path & path, const StorePathSet & refs);
-
 class RefScanSink : public Sink
 {
     StringSet hashes;
@@ -28,28 +23,18 @@ public:
     void operator () (std::string_view data) override;
 };
 
-class PathRefScanSink : public RefScanSink
-{
-    std::map<std::string, StorePath> backMap;
-
-    PathRefScanSink(StringSet && hashes, std::map<std::string, StorePath> && backMap);
-
-public:
-
-    static PathRefScanSink fromPaths(const StorePathSet & refs);
-
-    StorePathSet getResultPaths();
-};
-
 struct RewritingSink : Sink
 {
-    std::string from, to, prev;
+    const StringMap rewrites;
+    long unsigned int maxRewriteSize;
+    std::string prev;
     Sink & nextSink;
     uint64_t pos = 0;
 
     std::vector<uint64_t> matches;
 
     RewritingSink(const std::string & from, const std::string & to, Sink & nextSink);
+    RewritingSink(const StringMap & rewrites, Sink & nextSink);
 
     void operator () (std::string_view data) override;
 

src/libutil/tests/references.cc

@@ -0,0 +1,46 @@
+#include "references.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+using std::string;
+
+struct RewriteParams {
+    string originalString, finalString;
+    StringMap rewrites;
+
+    friend std::ostream& operator<<(std::ostream& os, const RewriteParams& bar) {
+        StringSet strRewrites;
+        for (auto & [from, to] : bar.rewrites)
+            strRewrites.insert(from + "->" + to);
+        return os <<
+            "OriginalString: " << bar.originalString << std::endl <<
+            "Rewrites: " << concatStringsSep(",", strRewrites) << std::endl <<
+            "Expected result: " << bar.finalString;
+    }
+};
+
+class RewriteTest : public ::testing::TestWithParam<RewriteParams> {
+};
+
+TEST_P(RewriteTest, IdentityRewriteIsIdentity) {
+    RewriteParams param = GetParam();
+    StringSink rewritten;
+    auto rewriter = RewritingSink(param.rewrites, rewritten);
+    rewriter(param.originalString);
+    rewriter.flush();
+    ASSERT_EQ(rewritten.s, param.finalString);
+}
+
+INSTANTIATE_TEST_CASE_P(
+    references,
+    RewriteTest,
+    ::testing::Values(
+        RewriteParams{ "foooo", "baroo", {{"foo", "bar"}, {"bar", "baz"}}},
+        RewriteParams{ "foooo", "bazoo", {{"fou", "bar"}, {"foo", "baz"}}},
+        RewriteParams{ "foooo", "foooo", {}}
+    )
+);
+
+}
+

src/libutil/util.hh

@@ -256,14 +256,12 @@ inline Paths createDirs(PathView path)
 /**
  * Create a symlink.
  */
-void createSymlink(const Path & target, const Path & link,
-    std::optional<time_t> mtime = {});
+void createSymlink(const Path & target, const Path & link);
 
 /**
  * Atomically create or replace a symlink.
  */
-void replaceSymlink(const Path & target, const Path & link,
-    std::optional<time_t> mtime = {});
+void replaceSymlink(const Path & target, const Path & link);
 
 void renameFile(const Path & src, const Path & dst);
 

src/nix-channel/nix-channel.cc

@@ -177,6 +177,7 @@ static int main_nix_channel(int argc, char ** argv)
             cRemove,
             cList,
             cUpdate,
+            cListGenerations,
             cRollback
         } cmd = cNone;
         std::vector<std::string> args;
@@ -193,6 +194,8 @@ static int main_nix_channel(int argc, char ** argv)
                 cmd = cList;
             } else if (*arg == "--update") {
                 cmd = cUpdate;
+            } else if (*arg == "--list-generations") {
+                cmd = cListGenerations;
             } else if (*arg == "--rollback") {
                 cmd = cRollback;
             } else {
@@ -237,6 +240,11 @@ static int main_nix_channel(int argc, char ** argv)
             case cUpdate:
                 update(StringSet(args.begin(), args.end()));
                 break;
+            case cListGenerations:
+                if (!args.empty())
+                    throw UsageError("'--list-generations' expects no arguments");
+                std::cout << runProgram(settings.nixBinDir + "/nix-env", false, {"--profile", profile, "--list-generations"}) << std::flush;
+                break;
             case cRollback:
                 if (args.size() > 1)
                     throw UsageError("'--rollback' has at most one argument");

src/nix/daemon.cc

@@ -24,6 +24,7 @@
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <sys/select.h>
 #include <errno.h>
 #include <pwd.h>
 #include <grp.h>