Merge remote-tracking branch 'upstream/master' into optional-derivation-output-storepath

31 files changed, 389 insertions, 412 deletions

diff --git a/Makefile.config.in b/Makefile.config.in
index b632444e8..5c245b8e9 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -19,6 +19,7 @@ LIBLZMA_LIBS = @LIBLZMA_LIBS@
 OPENSSL_LIBS = @OPENSSL_LIBS@
 PACKAGE_NAME = @PACKAGE_NAME@
 PACKAGE_VERSION = @PACKAGE_VERSION@
+SHELL = @bash@
 SODIUM_LIBS = @SODIUM_LIBS@
 SQLITE3_LIBS = @SQLITE3_LIBS@
 bash = @bash@
diff --git a/README.md b/README.md
index a1588284d..03c5deb7b 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ for more details.
 On Linux and macOS the easiest way to Install Nix is to run the following shell command
 (as a user other than root):
 
-```
+```console
 $ curl -L https://nixos.org/nix/install | sh
 ```
 
@@ -20,27 +20,8 @@ Information on additional installation methods is available on the [Nix download
 
 ## Building And Developing
 
-### Building Nix
-
-You can build Nix using one of the targets provided by [release.nix](./release.nix):
-
-```
-$ nix-build ./release.nix -A build.aarch64-linux
-$ nix-build ./release.nix -A build.x86_64-darwin
-$ nix-build ./release.nix -A build.i686-linux
-$ nix-build ./release.nix -A build.x86_64-linux
-```
-
-### Development Environment
-
-You can use the provided `shell.nix` to get a working development environment:
-
-```
-$ nix-shell
-$ ./bootstrap.sh
-$ ./configure
-$ make
-```
+See our [Hacking guide](https://hydra.nixos.org/job/nix/master/build.x86_64-linux/latest/download-by-type/doc/manual#chap-hacking) in our manual for instruction on how to
+build nix from source with nix-build or how to get a development environment.
 
 ## Additional Resources
 
diff --git a/doc/manual/expressions/builder-syntax.xml b/doc/manual/expressions/builder-syntax.xml
deleted file mode 100644
index e51bade44..000000000
--- a/doc/manual/expressions/builder-syntax.xml
+++ /dev/null
@@ -1,119 +0,0 @@
-<section xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      version="5.0"
-      xml:id='sec-builder-syntax'>
-
-<title>Builder Syntax</title>
-
-<example xml:id='ex-hello-builder'><title>Build script for GNU Hello
-(<filename>builder.sh</filename>)</title>
-<programlisting>
-source $stdenv/setup <co xml:id='ex-hello-builder-co-1' />
-
-PATH=$perl/bin:$PATH <co xml:id='ex-hello-builder-co-2' />
-
-tar xvfz $src <co xml:id='ex-hello-builder-co-3' />
-cd hello-*
-./configure --prefix=$out <co xml:id='ex-hello-builder-co-4' />
-make <co xml:id='ex-hello-builder-co-5' />
-make install</programlisting>
-</example>
-
-<para><xref linkend='ex-hello-builder' /> shows the builder referenced
-from Hello's Nix expression (stored in
-<filename>pkgs/applications/misc/hello/ex-1/builder.sh</filename>).
-The builder can actually be made a lot shorter by using the
-<emphasis>generic builder</emphasis> functions provided by
-<varname>stdenv</varname>, but here we write out the build steps to
-elucidate what a builder does.  It performs the following
-steps:</para>
-
-<calloutlist>
-
-  <callout arearefs='ex-hello-builder-co-1'>
-
-    <para>When Nix runs a builder, it initially completely clears the
-    environment (except for the attributes declared in the
-    derivation).  For instance, the <envar>PATH</envar> variable is
-    empty<footnote><para>Actually, it's initialised to
-    <filename>/path-not-set</filename> to prevent Bash from setting it
-    to a default value.</para></footnote>.  This is done to prevent
-    undeclared inputs from being used in the build process.  If for
-    example the <envar>PATH</envar> contained
-    <filename>/usr/bin</filename>, then you might accidentally use
-    <filename>/usr/bin/gcc</filename>.</para>
-
-    <para>So the first step is to set up the environment.  This is
-    done by calling the <filename>setup</filename> script of the
-    standard environment.  The environment variable
-    <envar>stdenv</envar> points to the location of the standard
-    environment being used.  (It wasn't specified explicitly as an
-    attribute in <xref linkend='ex-hello-nix' />, but
-    <varname>mkDerivation</varname> adds it automatically.)</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-builder-co-2'>
-
-    <para>Since Hello needs Perl, we have to make sure that Perl is in
-    the <envar>PATH</envar>.  The <envar>perl</envar> environment
-    variable points to the location of the Perl package (since it
-    was passed in as an attribute to the derivation), so
-    <filename><replaceable>$perl</replaceable>/bin</filename> is the
-    directory containing the Perl interpreter.</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-builder-co-3'>
-
-    <para>Now we have to unpack the sources.  The
-    <varname>src</varname> attribute was bound to the result of
-    fetching the Hello source tarball from the network, so the
-    <envar>src</envar> environment variable points to the location in
-    the Nix store to which the tarball was downloaded.  After
-    unpacking, we <command>cd</command> to the resulting source
-    directory.</para>
-
-    <para>The whole build is performed in a temporary directory
-    created in <varname>/tmp</varname>, by the way.  This directory is
-    removed after the builder finishes, so there is no need to clean
-    up the sources afterwards.  Also, the temporary directory is
-    always newly created, so you don't have to worry about files from
-    previous builds interfering with the current build.</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-builder-co-4'>
-
-    <para>GNU Hello is a typical Autoconf-based package, so we first
-    have to run its <filename>configure</filename> script.  In Nix
-    every package is stored in a separate location in the Nix store,
-    for instance
-    <filename>/nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1</filename>.
-    Nix computes this path by cryptographically hashing all attributes
-    of the derivation.  The path is passed to the builder through the
-    <envar>out</envar> environment variable.  So here we give
-    <filename>configure</filename> the parameter
-    <literal>--prefix=$out</literal> to cause Hello to be installed in
-    the expected location.</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-builder-co-5'>
-
-    <para>Finally we build Hello (<literal>make</literal>) and install
-    it into the location specified by <envar>out</envar>
-    (<literal>make install</literal>).</para>
-
-  </callout>
-
-</calloutlist>
-
-<para>If you are wondering about the absence of error checking on the
-result of various commands called in the builder: this is because the
-shell script is evaluated with Bash's <option>-e</option> option,
-which causes the script to be aborted if any command fails without an
-error check.</para>
-
-</section>
\ No newline at end of file
diff --git a/doc/manual/hacking.xml b/doc/manual/hacking.xml
index b671811d3..d25d4b84a 100644
--- a/doc/manual/hacking.xml
+++ b/doc/manual/hacking.xml
@@ -4,18 +4,37 @@
 
 <title>Hacking</title>
 
-<para>This section provides some notes on how to hack on Nix.  To get
+<para>This section provides some notes on how to hack on Nix. To get
 the latest version of Nix from GitHub:
 <screen>
-$ git clone git://github.com/NixOS/nix.git
+$ git clone https://github.com/NixOS/nix.git
 $ cd nix
 </screen>
 </para>
 
-<para>To build it and its dependencies:
+<para>To build Nix for the current operating system/architecture use
+
+<screen>
+$ nix-build
+</screen>
+
+or if you have a flakes-enabled nix:
+
+<screen>
+$ nix build
+</screen>
+
+This will build <literal>defaultPackage</literal> attribute defined in the <literal>flake.nix</literal> file.
+
+To build for other platforms add one of the following suffixes to it: aarch64-linux,
+i686-linux, x86_64-darwin, x86_64-linux.
+
+i.e.
+
 <screen>
-$ nix-build release.nix -A build.x86_64-linux
+nix-build -A defaultPackage.x86_64-linux
 </screen>
+
 </para>
 
 <para>To build all dependencies and start a shell in which all
@@ -27,13 +46,27 @@ $ nix-shell
 To build Nix itself in this shell:
 <screen>
 [nix-shell]$ ./bootstrap.sh
-[nix-shell]$ configurePhase
-[nix-shell]$ make
+[nix-shell]$ ./configure $configureFlags
+[nix-shell]$ make -j $NIX_BUILD_CORES
 </screen>
 To install it in <literal>$(pwd)/inst</literal> and test it:
 <screen>
 [nix-shell]$ make install
 [nix-shell]$ make installcheck
+[nix-shell]$ ./inst/bin/nix --version
+nix (Nix) 2.4
+</screen>
+
+If you have a flakes-enabled nix you can replace:
+
+<screen>
+$ nix-shell
+</screen>
+
+by:
+
+<screen>
+$ nix develop
 </screen>
 
 </para>
diff --git a/mk/precompiled-headers.mk b/mk/precompiled-headers.mk
index 1c0452dc2..500c99e4a 100644
--- a/mk/precompiled-headers.mk
+++ b/mk/precompiled-headers.mk
@@ -21,13 +21,13 @@ clean-files += $(GCH) $(PCH)
 
 ifeq ($(PRECOMPILE_HEADERS), 1)
 
-  ifeq ($(CXX), g++)
+  ifeq ($(findstring g++,$(CXX)), g++)
 
     GLOBAL_CXXFLAGS_PCH += -include $(buildprefix)precompiled-headers.h -Winvalid-pch
 
     GLOBAL_ORDER_AFTER += $(GCH)
 
-  else ifeq ($(CXX), clang++)
+  else ifeq ($(findstring clang++,$(CXX)), clang++)
 
     GLOBAL_CXXFLAGS_PCH += -include-pch $(PCH) -Winvalid-pch
 
diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index 5824c2217..6fb0beb2b 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -207,7 +207,7 @@ if [ -z "$NIX_INSTALLER_NO_MODIFY_PROFILE" ]; then
         if [ -w "$fn" ]; then
             if ! grep -q "$p" "$fn"; then
                 echo "modifying $fn..." >&2
-                echo "if [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
+                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
             fi
             added=1
             break
@@ -218,7 +218,7 @@ if [ -z "$NIX_INSTALLER_NO_MODIFY_PROFILE" ]; then
         if [ -w "$fn" ]; then
             if ! grep -q "$p" "$fn"; then
                 echo "modifying $fn..." >&2
-                echo "if [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
+                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
             fi
             added=1
             break
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 000000000..330df0ab6
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,3 @@
+(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
+  src = ./.;
+}).shellNix
diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 701546671..6363446f6 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -102,56 +102,61 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
             percentDecode(std::string(match[6])));
     }
 
-    /* Check if 'url' is a path (either absolute or relative to
-       'baseDir'). If so, search upward to the root of the repo
-       (i.e. the directory containing .git). */
-
     else if (std::regex_match(url, match, pathUrlRegex)) {
         std::string path = match[1];
-        if (!baseDir && !hasPrefix(path, "/"))
-            throw BadURL("flake reference '%s' is not an absolute path", url);
-        path = absPath(path, baseDir, true);
-
-        if (!S_ISDIR(lstat(path).st_mode))
-            throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
-
-        if (!allowMissing && !pathExists(path + "/flake.nix"))
-            throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
-
-        auto fragment = percentDecode(std::string(match[3]));
-
-        auto flakeRoot = path;
-        std::string subdir;
-
-        while (flakeRoot != "/") {
-            if (pathExists(flakeRoot + "/.git")) {
-                auto base = std::string("git+file://") + flakeRoot;
-
-                auto parsedURL = ParsedURL{
-                    .url = base, // FIXME
-                    .base = base,
-                    .scheme = "git+file",
-                    .authority = "",
-                    .path = flakeRoot,
-                    .query = decodeQuery(match[2]),
-                };
-
-                if (subdir != "") {
-                    if (parsedURL.query.count("dir"))
-                        throw Error("flake URL '%s' has an inconsistent 'dir' parameter", url);
-                    parsedURL.query.insert_or_assign("dir", subdir);
-                }
+        std::string fragment = percentDecode(std::string(match[3]));
+
+        if (baseDir) {
+            /* Check if 'url' is a path (either absolute or relative
+               to 'baseDir'). If so, search upward to the root of the
+               repo (i.e. the directory containing .git). */
+
+            path = absPath(path, baseDir, true);
+
+            if (!S_ISDIR(lstat(path).st_mode))
+                throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
+
+            if (!allowMissing && !pathExists(path + "/flake.nix"))
+                throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
 
-                if (pathExists(flakeRoot + "/.git/shallow"))
-                    parsedURL.query.insert_or_assign("shallow", "1");
+            auto flakeRoot = path;
+            std::string subdir;
+
+            while (flakeRoot != "/") {
+                if (pathExists(flakeRoot + "/.git")) {
+                    auto base = std::string("git+file://") + flakeRoot;
+
+                    auto parsedURL = ParsedURL{
+                        .url = base, // FIXME
+                        .base = base,
+                        .scheme = "git+file",
+                        .authority = "",
+                        .path = flakeRoot,
+                        .query = decodeQuery(match[2]),
+                    };
+
+                    if (subdir != "") {
+                        if (parsedURL.query.count("dir"))
+                            throw Error("flake URL '%s' has an inconsistent 'dir' parameter", url);
+                        parsedURL.query.insert_or_assign("dir", subdir);
+                    }
+
+                    if (pathExists(flakeRoot + "/.git/shallow"))
+                        parsedURL.query.insert_or_assign("shallow", "1");
+
+                    return std::make_pair(
+                        FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
+                        fragment);
+                }
 
-                return std::make_pair(
-                    FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
-                    fragment);
+                subdir = std::string(baseNameOf(flakeRoot)) + (subdir.empty() ? "" : "/" + subdir);
+                flakeRoot = dirOf(flakeRoot);
             }
 
-            subdir = std::string(baseNameOf(flakeRoot)) + (subdir.empty() ? "" : "/" + subdir);
-            flakeRoot = dirOf(flakeRoot);
+        } else {
+            if (!hasPrefix(path, "/"))
+                throw BadURL("flake reference '%s' is not an absolute path", url);
+            path = canonPath(path);
         }
 
         fetchers::Attrs attrs;
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 1c88d91bc..109368f8a 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2774,7 +2774,7 @@ struct RestrictedStore : public LocalFSStore
         goal.addDependency(info.path);
     }
 
-    StorePath addToStoreFromDump(const string & dump, const string & name,
+    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);
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index e574ea1a7..df295084a 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -173,31 +173,6 @@ struct TunnelSource : BufferedSource
     }
 };
 
-/* If the NAR archive contains a single file at top-level, then save
-   the contents of the file to `s'.  Otherwise barf. */
-struct RetrieveRegularNARSink : ParseSink
-{
-    bool regular;
-    string s;
-
-    RetrieveRegularNARSink() : regular(true) { }
-
-    void createDirectory(const Path & path)
-    {
-        regular = false;
-    }
-
-    void receiveContents(unsigned char * data, unsigned int len)
-    {
-        s.append((const char *) data, len);
-    }
-
-    void createSymlink(const Path & path, const string & target)
-    {
-        regular = false;
-    }
-};
-
 struct ClientSettings
 {
     bool keepFailed;
@@ -375,25 +350,28 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddToStore: {
-        std::string s, baseName;
+        HashType hashAlgo;
+        std::string baseName;
         FileIngestionMethod method;
         {
-            bool fixed; uint8_t recursive;
-            from >> baseName >> fixed /* obsolete */ >> recursive >> s;
+            bool fixed;
+            uint8_t recursive;
+            std::string hashAlgoRaw;
+            from >> baseName >> fixed /* obsolete */ >> recursive >> hashAlgoRaw;
             if (recursive > (uint8_t) FileIngestionMethod::Recursive)
                 throw Error("unsupported FileIngestionMethod with value of %i; you may need to upgrade nix-daemon", recursive);
             method = FileIngestionMethod { recursive };
             /* Compatibility hack. */
             if (!fixed) {
-                s = "sha256";
+                hashAlgoRaw = "sha256";
                 method = FileIngestionMethod::Recursive;
             }
+            hashAlgo = parseHashType(hashAlgoRaw);
         }
-        HashType hashAlgo = parseHashType(s);
 
-        StringSink savedNAR;
-        TeeSource savedNARSource(from, savedNAR);
-        RetrieveRegularNARSink savedRegular;
+        StringSink saved;
+        TeeSource savedNARSource(from, saved);
+        RetrieveRegularNARSink savedRegular { saved };
 
         if (method == FileIngestionMethod::Recursive) {
             /* Get the entire NAR dump from the client and save it to
@@ -407,11 +385,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         if (!savedRegular.regular) throw Error("regular file expected");
 
-        auto path = store->addToStoreFromDump(
-            method == FileIngestionMethod::Recursive ? *savedNAR.s : savedRegular.s,
-            baseName,
-            method,
-            hashAlgo);
+        // FIXME: try to stream directly from `from`.
+        StringSource dumpSource { *saved.s };
+        auto path = store->addToStoreFromDump(dumpSource, baseName, method, hashAlgo);
         logger->stopWork();
 
         to << store->printStorePath(path);
@@ -727,15 +703,15 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         if (!trusted)
             info.ultimate = false;
 
-        std::string saved;
         std::unique_ptr<Source> source;
         if (GET_PROTOCOL_MINOR(clientVersion) >= 21)
             source = std::make_unique<TunnelSource>(from, to);
         else {
-            TeeParseSink tee(from);
-            parseDump(tee, tee.source);
-            saved = std::move(*tee.saved.s);
-            source = std::make_unique<StringSource>(saved);
+            StringSink saved;
+            TeeSource tee { from, saved };
+            ParseSink ether;
+            parseDump(ether, tee);
+            source = std::make_unique<StringSource>(std::move(*saved.s));
         }
 
         logger->startWork();
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index e74e46dda..7d0a5abeb 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -23,14 +23,6 @@ StorePath DerivationOutput::path(const Store & store, std::string_view drvName)
     }, output);
 }
 
-const StorePath BasicDerivation::findOutput(const Store & store, const string & id) const
-{
-    auto i = outputs.find(id);
-    if (i == outputs.end())
-        throw Error("derivation has no output '%s'", id);
-    return i->second.path(store, name);
-}
-
 
 bool BasicDerivation::isBuiltin() const
 {
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index fd8828373..133ffe50e 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -50,10 +50,6 @@ struct BasicDerivation
     BasicDerivation() { }
     virtual ~BasicDerivation() { };
 
-    /* Return the path corresponding to the output identifier `id' in
-       the given derivation. */
-    const StorePath findOutput(const Store & store, const std::string & id) const;
-
     bool isBuiltin() const;
 
     /* Return true iff this is a fixed-output derivation. */
diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index 082d0f1d1..b963d64d7 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -60,8 +60,10 @@ StorePaths Store::importPaths(Source & source, CheckSigsFlag checkSigs)
         if (n != 1) throw Error("input doesn't look like something created by 'nix-store --export'");
 
         /* Extract the NAR from the source. */
-        TeeParseSink tee(source);
-        parseDump(tee, tee.source);
+        StringSink saved;
+        TeeSource tee { source, saved };
+        ParseSink ether;
+        parseDump(ether, tee);
 
         uint32_t magic = readInt(source);
         if (magic != exportMagic)
@@ -77,15 +79,15 @@ StorePaths Store::importPaths(Source & source, CheckSigsFlag checkSigs)
         if (deriver != "")
             info.deriver = parseStorePath(deriver);
 
-        info.narHash = hashString(htSHA256, *tee.saved.s);
-        info.narSize = tee.saved.s->size();
+        info.narHash = hashString(htSHA256, *saved.s);
+        info.narSize = saved.s->size();
 
         // Ignore optional legacy signature.
         if (readInt(source) == 1)
             readString(source);
 
         // Can't use underlying source, which would have been exhausted
-        auto source = StringSource { *tee.saved.s };
+        auto source = StringSource { *saved.s };
         addToStore(info, source, NoRepair, checkSigs);
 
         res.push_back(info.path);
diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index beb508e67..4149f8155 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -124,7 +124,7 @@ struct curlFileTransfer : public FileTransfer
             if (requestHeaders) curl_slist_free_all(requestHeaders);
             try {
                 if (!done)
-                    fail(FileTransferError(Interrupted, "download of '%s' was interrupted", request.uri));
+                    fail(FileTransferError(Interrupted, nullptr, "download of '%s' was interrupted", request.uri));
             } catch (...) {
                 ignoreException();
             }
@@ -145,6 +145,7 @@ struct curlFileTransfer : public FileTransfer
 
         LambdaSink finalSink;
         std::shared_ptr<CompressionSink> decompressionSink;
+        std::optional<StringSink> errorSink;
 
         std::exception_ptr writeException;
 
@@ -154,9 +155,19 @@ struct curlFileTransfer : public FileTransfer
                 size_t realSize = size * nmemb;
                 result.bodySize += realSize;
 
-                if (!decompressionSink)
+                if (!decompressionSink) {
                     decompressionSink = makeDecompressionSink(encoding, finalSink);
+                    if (! successfulStatuses.count(getHTTPStatus())) {
+                        // In this case we want to construct a TeeSink, to keep
+                        // the response around (which we figure won't be big
+                        // like an actual download should be) to improve error
+                        // messages.
+                        errorSink = StringSink { };
+                    }
+                }
 
+                if (errorSink)
+                    (*errorSink)((unsigned char *) contents, realSize);
                 (*decompressionSink)((unsigned char *) contents, realSize);
 
                 return realSize;
@@ -412,16 +423,21 @@ struct curlFileTransfer : public FileTransfer
 
                 attempt++;
 
+                std::shared_ptr<std::string> response;
+                if (errorSink)
+                    response = errorSink->s;
                 auto exc =
                     code == CURLE_ABORTED_BY_CALLBACK && _isInterrupted
-                    ? FileTransferError(Interrupted, fmt("%s of '%s' was interrupted", request.verb(), request.uri))
+                    ? FileTransferError(Interrupted, response, "%s of '%s' was interrupted", request.verb(), request.uri)
                     : httpStatus != 0
                     ? FileTransferError(err,
+                        response,
                         fmt("unable to %s '%s': HTTP error %d ('%s')",
                             request.verb(), request.uri, httpStatus, statusMsg)
                         + (code == CURLE_OK ? "" : fmt(" (curl error: %s)", curl_easy_strerror(code)))
                         )
                     : FileTransferError(err,
+                        response,
                         fmt("unable to %s '%s': %s (%d)",
                             request.verb(), request.uri, curl_easy_strerror(code), code));
 
@@ -679,7 +695,7 @@ struct curlFileTransfer : public FileTransfer
                 auto s3Res = s3Helper.getObject(bucketName, key);
                 FileTransferResult res;
                 if (!s3Res.data)
-                    throw FileTransferError(NotFound, fmt("S3 object '%s' does not exist", request.uri));
+                    throw FileTransferError(NotFound, nullptr, "S3 object '%s' does not exist", request.uri);
                 res.data = s3Res.data;
                 callback(std::move(res));
 #else
@@ -824,6 +840,21 @@ void FileTransfer::download(FileTransferRequest && request, Sink & sink)
     }
 }
 
+template<typename... Args>
+FileTransferError::FileTransferError(FileTransfer::Error error, std::shared_ptr<string> response, const Args & ... args)
+    : Error(args...), error(error), response(response)
+{
+    const auto hf = hintfmt(args...);
+    // FIXME: Due to https://github.com/NixOS/nix/issues/3841 we don't know how
+    // to print different messages for different verbosity levels. For now
+    // we add some heuristics for detecting when we want to show the response.
+    if (response && (response->size() < 1024 || response->find("<html>") != string::npos)) {
+            err.hint = hintfmt("%1%\n\nresponse body:\n\n%2%", normaltxt(hf.str()), *response);
+    } else {
+        err.hint = hf;
+    }
+}
+
 bool isUri(const string & s)
 {
     if (s.compare(0, 8, "channel:") == 0) return true;
diff --git a/src/libstore/filetransfer.hh b/src/libstore/filetransfer.hh
index 11dca2fe0..25ade0add 100644
--- a/src/libstore/filetransfer.hh
+++ b/src/libstore/filetransfer.hh
@@ -103,10 +103,12 @@ class FileTransferError : public Error
 {
 public:
     FileTransfer::Error error;
+    std::shared_ptr<string> response; // intentionally optional
+
     template<typename... Args>
-    FileTransferError(FileTransfer::Error error, const Args & ... args)
-        : Error(args...), error(error)
-    { }
+    FileTransferError(FileTransfer::Error error, std::shared_ptr<string> response, const Args & ... args);
+
+    virtual const char* sname() const override { return "FileTransferError"; }
 };
 
 bool isUri(const string & s);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index d1a3b95c1..1e6b34cd1 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1026,82 +1026,26 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 }
 
 
-StorePath LocalStore::addToStoreFromDump(const string & dump, const string & name,
-    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
-{
-    Hash h = hashString(hashAlgo, dump);
-
-    auto dstPath = makeFixedOutputPath(method, h, name);
-
-    addTempRoot(dstPath);
-
-    if (repair || !isValidPath(dstPath)) {
-
-        /* The first check above is an optimisation to prevent
-           unnecessary lock acquisition. */
-
-        auto realPath = Store::toRealPath(dstPath);
-
-        PathLocks outputLock({realPath});
-
-        if (repair || !isValidPath(dstPath)) {
-
-            deletePath(realPath);
-
-            autoGC();
-
-            if (method == FileIngestionMethod::Recursive) {
-                StringSource source(dump);
-                restorePath(realPath, source);
-            } else
-                writeFile(realPath, dump);
-
-            canonicalisePathMetaData(realPath, -1);
-
-            /* Register the SHA-256 hash of the NAR serialisation of
-               the path in the database.  We may just have computed it
-               above (if called with recursive == true and hashAlgo ==
-               sha256); otherwise, compute it here. */
-            HashResult hash;
-            if (method == FileIngestionMethod::Recursive) {
-                hash.first = hashAlgo == htSHA256 ? h : hashString(htSHA256, dump);
-                hash.second = dump.size();
-            } else
-                hash = hashPath(htSHA256, realPath);
-
-            optimisePath(realPath); // FIXME: combine with hashPath()
-
-            ValidPathInfo info(dstPath);
-            info.narHash = hash.first;
-            info.narSize = hash.second;
-            info.ca = FixedOutputHash { .method = method, .hash = h };
-            registerValidPath(info);
-        }
-
-        outputLock.setDeletion(true);
-    }
-
-    return dstPath;
-}
-
-
 StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
     FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
 {
     Path srcPath(absPath(_srcPath));
+    auto source = sinkToSource([&](Sink & sink) {
+        if (method == FileIngestionMethod::Recursive)
+            dumpPath(srcPath, sink, filter);
+        else
+            readFile(srcPath, sink);
+    });
+    return addToStoreFromDump(*source, name, method, hashAlgo, repair);
+}
 
-    if (method != FileIngestionMethod::Recursive)
-        return addToStoreFromDump(readFile(srcPath), name, method, hashAlgo, repair);
-
-    /* For computing the NAR hash. */
-    auto sha256Sink = std::make_unique<HashSink>(htSHA256);
 
-    /* For computing the store path. In recursive SHA-256 mode, this
-       is the same as the NAR hash, so no need to do it again. */
-    std::unique_ptr<HashSink> hashSink =
-        hashAlgo == htSHA256
-        ? nullptr
-        : std::make_unique<HashSink>(hashAlgo);
+StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
+{
+    /* For computing the store path. */
+    auto hashSink = std::make_unique<HashSink>(hashAlgo);
+    TeeSource source { source0, *hashSink };
 
     /* Read the source path into memory, but only if it's up to
        narBufferSize bytes. If it's larger, write it to a temporary
@@ -1109,55 +1053,49 @@ StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
        destination store path is already valid, we just delete the
        temporary path. Otherwise, we move it to the destination store
        path. */
-    bool inMemory = true;
-    std::string nar;
-
-    auto source = sinkToSource([&](Sink & sink) {
-
-        LambdaSink sink2([&](const unsigned char * buf, size_t len) {
-            (*sha256Sink)(buf, len);
-            if (hashSink) (*hashSink)(buf, len);
-
-            if (inMemory) {
-                if (nar.size() + len > settings.narBufferSize) {
-                    inMemory = false;
-                    sink << 1;
-                    sink((const unsigned char *) nar.data(), nar.size());
-                    nar.clear();
-                } else {
-                    nar.append((const char *) buf, len);
-                }
-            }
-
-            if (!inMemory) sink(buf, len);
-        });
-
-        dumpPath(srcPath, sink2, filter);
-    });
+    bool inMemory = false;
+
+    std::string dump;
+
+    /* Fill out buffer, and decide whether we are working strictly in
+       memory based on whether we break out because the buffer is full
+       or the original source is empty */
+    while (dump.size() < settings.narBufferSize) {
+        auto oldSize = dump.size();
+        constexpr size_t chunkSize = 65536;
+        auto want = std::min(chunkSize, settings.narBufferSize - oldSize);
+        dump.resize(oldSize + want);
+        auto got = 0;
+        try {
+            got = source.read((uint8_t *) dump.data() + oldSize, want);
+        } catch (EndOfFile &) {
+            inMemory = true;
+            break;
+        }
+        dump.resize(oldSize + got);
+    }
 
     std::unique_ptr<AutoDelete> delTempDir;
     Path tempPath;
 
-    try {
-        /* Wait for the source coroutine to give us some dummy
-           data. This is so that we don't create the temporary
-           directory if the NAR fits in memory. */
-        readInt(*source);
+    if (!inMemory) {
+        /* Drain what we pulled so far, and then keep on pulling */
+        StringSource dumpSource { dump };
+        ChainSource bothSource { dumpSource, source };
 
         auto tempDir = createTempDir(realStoreDir, "add");
         delTempDir = std::make_unique<AutoDelete>(tempDir);
         tempPath = tempDir + "/x";
 
-        restorePath(tempPath, *source);
+        if (method == FileIngestionMethod::Recursive)
+            restorePath(tempPath, bothSource);
+        else
+            writeFile(tempPath, bothSource);
 
-    } catch (EndOfFile &) {
-        if (!inMemory) throw;
-        /* The NAR fits in memory, so we didn't do restorePath(). */
+        dump.clear();
     }
 
-    auto sha256 = sha256Sink->finish();
-
-    Hash hash = hashSink ? hashSink->finish().first : sha256.first;
+    auto [hash, size] = hashSink->finish();
 
     auto dstPath = makeFixedOutputPath(method, hash, name);
 
@@ -1179,22 +1117,34 @@ StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
             autoGC();
 
             if (inMemory) {
+                 StringSource dumpSource { dump };
                 /* Restore from the NAR in memory. */
-                StringSource source(nar);
-                restorePath(realPath, source);
+                if (method == FileIngestionMethod::Recursive)
+                    restorePath(realPath, dumpSource);
+                else
+                    writeFile(realPath, dumpSource);
             } else {
                 /* Move the temporary path we restored above. */
                 if (rename(tempPath.c_str(), realPath.c_str()))
                     throw Error("renaming '%s' to '%s'", tempPath, realPath);
             }
 
+            /* For computing the nar hash. In recursive SHA-256 mode, this
+               is the same as the store hash, so no need to do it again. */
+            auto narHash = std::pair { hash, size };
+            if (method != FileIngestionMethod::Recursive || hashAlgo != htSHA256) {
+                HashSink narSink { htSHA256 };
+                dumpPath(realPath, narSink);
+                narHash = narSink.finish();
+            }
+
             canonicalisePathMetaData(realPath, -1); // FIXME: merge into restorePath
 
             optimisePath(realPath);
 
             ValidPathInfo info(dstPath);
-            info.narHash = sha256.first;
-            info.narSize = sha256.second;
+            info.narHash = narHash.first;
+            info.narSize = narHash.second;
             info.ca = FixedOutputHash { .method = method, .hash = hash };
             registerValidPath(info);
         }
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index c0e5d0286..355c2814f 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -153,7 +153,7 @@ public:
        in `dump', which is either a NAR serialisation (if recursive ==
        true) or simply the contents of a regular file (if recursive ==
        false). */
-    StorePath addToStoreFromDump(const string & dump, const string & name,
+    StorePath addToStoreFromDump(Source & dump, const string & name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override;
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index a10d536a3..968e2e425 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -48,13 +48,12 @@ static void search(const unsigned char * s, size_t len,
 
 struct RefScanSink : Sink
 {
-    HashSink hashSink;
     StringSet hashes;
     StringSet seen;
 
     string tail;
 
-    RefScanSink() : hashSink(htSHA256) { }
+    RefScanSink() { }
 
     void operator () (const unsigned char * data, size_t len);
 };
@@ -62,8 +61,6 @@ struct RefScanSink : Sink
 
 void RefScanSink::operator () (const unsigned char * data, size_t len)
 {
-    hashSink(data, len);
-
     /* It's possible that a reference spans the previous and current
        fragment, so search in the concatenation of the tail of the
        previous fragment and the start of the current fragment. */
@@ -82,7 +79,9 @@ void RefScanSink::operator () (const unsigned char * data, size_t len)
 PathSet scanForReferences(const string & path,
     const PathSet & refs, HashResult & hash)
 {
-    RefScanSink sink;
+    RefScanSink refsSink;
+    HashSink hashSink { htSHA256 };
+    TeeSink sink { refsSink, hashSink };
     std::map<string, Path> backMap;
 
     /* For efficiency (and a higher hit rate), just search for the
@@ -97,7 +96,7 @@ PathSet scanForReferences(const string & path,
         assert(s.size() == refLength);
         assert(backMap.find(s) == backMap.end());
         // parseHash(htSHA256, s);
-        sink.hashes.insert(s);
+        refsSink.hashes.insert(s);
         backMap[s] = i;
     }
 
@@ -106,13 +105,13 @@ PathSet scanForReferences(const string & path,
 
     /* Map the hashes found back to their store paths. */
     PathSet found;
-    for (auto & i : sink.seen) {
+    for (auto & i : refsSink.seen) {
         std::map<string, Path>::iterator j;
         if ((j = backMap.find(i)) == backMap.end()) abort();
         found.insert(j->second);
     }
 
-    hash = sink.hashSink.finish();
+    hash = hashSink.finish();
 
     return found;
 }
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 5b9f79049..ab21b0bd5 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -222,20 +222,73 @@ StorePath Store::computeStorePathForText(const string & name, const string & s,
 }
 
 
+/*
+The aim of this function is to compute in one pass the correct ValidPathInfo for
+the files that we are trying to add to the store. To accomplish that in one
+pass, given the different kind of inputs that we can take (normal nar archives,
+nar archives with non SHA-256 hashes, and flat files), we set up a net of sinks
+and aliases. Also, since the dataflow is obfuscated by this, we include here a
+graphviz diagram:
+
+digraph graphname {
+    node [shape=box]
+    fileSource -> narSink
+    narSink [style=dashed]
+    narSink -> unsualHashTee [style = dashed, label = "Recursive && !SHA-256"]
+    narSink -> narHashSink [style = dashed, label = "else"]
+    unsualHashTee -> narHashSink
+    unsualHashTee -> caHashSink
+    fileSource -> parseSink
+    parseSink [style=dashed]
+    parseSink-> fileSink [style = dashed, label = "Flat"]
+    parseSink -> blank [style = dashed, label = "Recursive"]
+    fileSink -> caHashSink
+}
+*/
 ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
     FileIngestionMethod method, HashType hashAlgo,
     std::optional<Hash> expectedCAHash)
 {
-    /* FIXME: inefficient: we're reading/hashing 'tmpFile' three
-       times. */
+    HashSink narHashSink { htSHA256 };
+    HashSink caHashSink { hashAlgo };
+
+    /* Note that fileSink and unusualHashTee must be mutually exclusive, since
+       they both write to caHashSink. Note that that requisite is currently true
+       because the former is only used in the flat case. */
+    RetrieveRegularNARSink fileSink { caHashSink };
+    TeeSink unusualHashTee { narHashSink, caHashSink };
+
+    auto & narSink = method == FileIngestionMethod::Recursive && hashAlgo != htSHA256
+        ? static_cast<Sink &>(unusualHashTee)
+        : narHashSink;
+
+    /* Functionally, this means that fileSource will yield the content of
+       srcPath. The fact that we use scratchpadSink as a temporary buffer here
+       is an implementation detail. */
+    auto fileSource = sinkToSource([&](Sink & scratchpadSink) {
+        dumpPath(srcPath, scratchpadSink);
+    });
 
-    auto [narHash, narSize] = hashPath(htSHA256, srcPath);
+    /* tapped provides the same data as fileSource, but we also write all the
+       information to narSink. */
+    TeeSource tapped { *fileSource, narSink };
 
-    auto hash = method == FileIngestionMethod::Recursive
-        ? hashAlgo == htSHA256
-          ? narHash
-          : hashPath(hashAlgo, srcPath).first
-        : hashFile(hashAlgo, srcPath);
+    ParseSink blank;
+    auto & parseSink = method == FileIngestionMethod::Flat
+        ? fileSink
+        : blank;
+
+    /* The information that flows from tapped (besides being replicated in
+       narSink), is now put in parseSink. */
+    parseDump(parseSink, tapped);
+
+    /* We extract the result of the computation from the sink by calling
+       finish. */
+    auto [narHash, narSize] = narHashSink.finish();
+
+    auto hash = method == FileIngestionMethod::Recursive && hashAlgo == htSHA256
+        ? narHash
+        : caHashSink.finish().first;
 
     if (expectedCAHash && expectedCAHash != hash)
         throw Error("hash mismatch for '%s'", srcPath);
@@ -246,8 +299,8 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
     info.ca = FixedOutputHash { .method = method, .hash = hash };
 
     if (!isValidPath(info.path)) {
-        auto source = sinkToSource([&](Sink & sink) {
-            dumpPath(srcPath, sink);
+        auto source = sinkToSource([&](Sink & scratchpadSink) {
+            dumpPath(srcPath, scratchpadSink);
         });
         addToStore(info, *source);
     }
@@ -914,12 +967,20 @@ ref<Store> openStore(const std::string & uri_,
     throw Error("don't know how to open Nix store '%s'", uri);
 }
 
+static bool isNonUriPath(const std::string & spec) {
+    return
+        // is not a URL
+        spec.find("://") == std::string::npos
+        // Has at least one path separator, and so isn't a single word that
+        // might be special like "auto"
+        && spec.find("/") != std::string::npos;
+}
 
 StoreType getStoreType(const std::string & uri, const std::string & stateDir)
 {
     if (uri == "daemon") {
         return tDaemon;
-    } else if (uri == "local" || hasPrefix(uri, "/")) {
+    } else if (uri == "local" || isNonUriPath(uri)) {
         return tLocal;
     } else if (uri == "" || uri == "auto") {
         if (access(stateDir.c_str(), R_OK | W_OK) == 0)
@@ -943,8 +1004,9 @@ static RegisterStoreImplementation regStore([](
             return std::shared_ptr<Store>(std::make_shared<UDSRemoteStore>(params));
         case tLocal: {
             Store::Params params2 = params;
-            if (hasPrefix(uri, "/"))
-                params2["root"] = uri;
+            if (isNonUriPath(uri)) {
+                params2["root"] = absPath(uri);
+            }
             return std::shared_ptr<Store>(std::make_shared<LocalStore>(params2));
         }
         default:
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index a4be0411e..d1cb2035f 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -460,7 +460,7 @@ public:
         std::optional<Hash> expectedCAHash = {});
 
     // FIXME: remove?
-    virtual StorePath addToStoreFromDump(const string & dump, const string & name,
+    virtual StorePath addToStoreFromDump(Source & dump, const string & name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair)
     {
         throw Error("addToStoreFromDump() is not supported by this store");
diff --git a/src/libutil/archive.hh b/src/libutil/archive.hh
index 302b1bb18..57780d16a 100644
--- a/src/libutil/archive.hh
+++ b/src/libutil/archive.hh
@@ -63,12 +63,29 @@ struct ParseSink
     virtual void createSymlink(const Path & path, const string & target) { };
 };
 
-struct TeeParseSink : ParseSink
+/* If the NAR archive contains a single file at top-level, then save
+   the contents of the file to `s'.  Otherwise barf. */
+struct RetrieveRegularNARSink : ParseSink
 {
-    StringSink saved;
-    TeeSource source;
+    bool regular = true;
+    Sink & sink;
 
-    TeeParseSink(Source & source) : source(source, saved) { }
+    RetrieveRegularNARSink(Sink & sink) : sink(sink) { }
+
+    void createDirectory(const Path & path)
+    {
+        regular = false;
+    }
+
+    void receiveContents(unsigned char * data, unsigned int len)
+    {
+        sink(data, len);
+    }
+
+    void createSymlink(const Path & path, const string & target)
+    {
+        regular = false;
+    }
 };
 
 void parseDump(ParseSink & sink, Source & source);
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index c8b71188f..00c945113 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -322,5 +322,18 @@ void StringSink::operator () (const unsigned char * data, size_t len)
     s->append((const char *) data, len);
 }
 
+size_t ChainSource::read(unsigned char * data, size_t len)
+{
+    if (useSecond) {
+        return source2.read(data, len);
+    } else {
+        try {
+            return source1.read(data, len);
+        } catch (EndOfFile &) {
+            useSecond = true;
+            return this->read(data, len);
+        }
+    }
+}
 
 }
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 8386a4991..5d9acf887 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -189,7 +189,7 @@ struct TeeSource : Source
     size_t read(unsigned char * data, size_t len)
     {
         size_t n = orig.read(data, len);
-        sink(data, len);
+        sink(data, n);
         return n;
     }
 };
@@ -256,6 +256,19 @@ struct LambdaSource : Source
     }
 };
 
+/* Chain two sources together so after the first is exhausted, the second is
+   used */
+struct ChainSource : Source
+{
+    Source & source1, & source2;
+    bool useSecond = false;
+    ChainSource(Source & s1, Source & s2)
+        : source1(s1), source2(s2)
+    { }
+
+    size_t read(unsigned char * data, size_t len) override;
+};
+
 
 /* Convert a function that feeds data into a Sink into a Source. The
    Source executes the function as a coroutine. */
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 93798a765..a0a8ff4d3 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1581,7 +1581,7 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
 
     struct sockaddr_un addr;
     addr.sun_family = AF_UNIX;
-    if (path.size() >= sizeof(addr.sun_path))
+    if (path.size() + 1 >= sizeof(addr.sun_path))
         throw Error("socket path '%1%' is too long", path);
     strcpy(addr.sun_path, path.c_str());
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 1a36dbee3..ddd036070 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -381,7 +381,8 @@ static void queryInstSources(EvalState & state,
 
                 if (path.isDerivation()) {
                     elem.setDrvPath(state.store->printStorePath(path));
-                    elem.setOutPath(state.store->printStorePath(state.store->derivationFromPath(path).findOutput(*state.store, "out")));
+                    auto outputs = state.store->queryDerivationOutputMap(path);
+                    elem.setOutPath(state.store->printStorePath(outputs.at("out")));
                     if (name.size() >= drvExtension.size() &&
                         string(name, name.size() - drvExtension.size()) == drvExtension)
                         name = string(name, 0, name.size() - drvExtension.size());
diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index dc9775635..378a3739c 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -45,6 +45,7 @@ struct CmdEdit : InstallableCommand
 
         auto args = editorFor(pos);
 
+        restoreSignals();
         execvp(args.front().c_str(), stringsToCharPtrs(args).data());
 
         std::string command;
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 729924e3a..c6cd88c49 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -395,7 +395,7 @@ struct CmdProfileInfo : virtual EvalCommand, virtual StoreCommand, MixDefaultPro
     }
 };
 
-struct CmdProfileDiffClosures : virtual EvalCommand, virtual StoreCommand, MixDefaultProfile
+struct CmdProfileDiffClosures : virtual StoreCommand, MixDefaultProfile
 {
     std::string description() override
     {
diff --git a/src/nix/registry.cc b/src/nix/registry.cc
index 16d7e511f..ebee4545c 100644
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@@ -111,6 +111,7 @@ struct CmdRegistryPin : virtual Args, EvalCommand
         fetchers::Attrs extraAttrs;
         if (ref.subdir != "") extraAttrs["dir"] = ref.subdir;
         userRegistry->add(ref.input, resolved, extraAttrs);
+        userRegistry->write(fetchers::getUserRegistryPath());
     }
 };
 
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 25e1847e1..5aec563ac 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -18,7 +18,6 @@ registry=$TEST_ROOT/registry.json
 flake1Dir=$TEST_ROOT/flake1
 flake2Dir=$TEST_ROOT/flake2
 flake3Dir=$TEST_ROOT/flake3
-flake4Dir=$TEST_ROOT/flake4
 flake5Dir=$TEST_ROOT/flake5
 flake6Dir=$TEST_ROOT/flake6
 flake7Dir=$TEST_ROOT/flake7
@@ -390,14 +389,12 @@ cat > $flake3Dir/flake.nix <<EOF
   };
 }
 EOF
-git -C $flake3Dir add flake.nix
+nix flake update $flake3Dir
+git -C $flake3Dir add flake.nix flake.lock
 git -C $flake3Dir commit -m 'Remove packages.xyzzy'
 git -C $flake3Dir checkout master
 
-# Test whether fuzzy-matching works for IsAlias
-(! nix build -o $TEST_ROOT/result flake4/removeXyzzy#xyzzy)
-
-# Test whether fuzzy-matching works for IsGit
+# Test whether fuzzy-matching works for registry entries.
 (! nix build -o $TEST_ROOT/result flake4/removeXyzzy#xyzzy)
 nix build -o $TEST_ROOT/result flake4/removeXyzzy#sth
 
diff --git a/tests/local-store.sh b/tests/local-store.sh
new file mode 100644
index 000000000..4ec3d64b0
--- /dev/null
+++ b/tests/local-store.sh
@@ -0,0 +1,20 @@
+source common.sh
+
+cd $TEST_ROOT
+
+echo example > example.txt
+mkdir -p ./x
+
+NIX_STORE_DIR=$TEST_ROOT/x
+
+CORRECT_PATH=$(nix-store --store ./x --add example.txt)
+
+PATH1=$(nix path-info --store ./x $CORRECT_PATH)
+[ $CORRECT_PATH == $PATH1 ]
+
+PATH2=$(nix path-info --store "$PWD/x" $CORRECT_PATH)
+[ $CORRECT_PATH == $PATH2 ]
+
+# FIXME we could also test the query parameter version:
+# PATH3=$(nix path-info --store "local?store=$PWD/x" $CORRECT_PATH)
+# [ $CORRECT_PATH == $PATH3 ]
diff --git a/tests/local.mk b/tests/local.mk
index 81366160b..0f3bfe606 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -6,7 +6,7 @@ nix_tests = \
   gc-auto.sh \
   referrers.sh user-envs.sh logging.sh nix-build.sh misc.sh fixed.sh \
   gc-runtime.sh check-refs.sh filter-source.sh \
-  remote-store.sh export.sh export-graph.sh \
+  local-store.sh remote-store.sh export.sh export-graph.sh \
   timeout.sh secure-drv-outputs.sh nix-channel.sh \
   multiple-outputs.sh import-derivation.sh fetchurl.sh optimise-store.sh \
   binary-cache.sh nix-profile.sh repair.sh dump-db.sh case-hack.sh \