Merge remote-tracking branch 'upstream/master' into better-ca-parse-errors

9 files changed, 200 insertions, 231 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 0c128d757..7d82ef09b 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 33b6ab9b1..9e138e8d9 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/export-import.cc b/src/libstore/export-import.cc
index e0622fb31..a0fc22264 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/local-store.cc b/src/libstore/local-store.cc
index 135419af7..b053d9b76 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1033,82 +1033,26 @@ 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 = method == FileIngestionMethod::Recursive
-                ? HashResult {
-                    hashAlgo == htSHA256 ? h : hashString(htSHA256, dump),
-                    dump.size(),
-                  }
-                : 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
@@ -1116,55 +1060,49 @@ 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 = 1024;
+        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);
 
@@ -1186,22 +1124,34 @@ 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/profiles.cc b/src/libstore/profiles.cc
index 6cfe393a4..6862b42f0 100644
--- a/src/libstore/profiles.cc
+++ b/src/libstore/profiles.cc
@@ -12,30 +12,24 @@
 namespace nix {
 
 
-static bool cmpGensByNumber(const Generation & a, const Generation & b)
-{
-    return a.number < b.number;
-}
-
-
 /* Parse a generation name of the format
    `<profilename>-<number>-link'. */
-static int parseName(const string & profileName, const string & name)
+static std::optional<GenerationNumber> parseName(const string & profileName, const string & name)
 {
-    if (string(name, 0, profileName.size() + 1) != profileName + "-") return -1;
+    if (string(name, 0, profileName.size() + 1) != profileName + "-") return {};
     string s = string(name, profileName.size() + 1);
     string::size_type p = s.find("-link");
-    if (p == string::npos) return -1;
-    int n;
+    if (p == string::npos) return {};
+    unsigned int n;
     if (string2Int(string(s, 0, p), n) && n >= 0)
         return n;
     else
-        return -1;
+        return {};
 }
 
 
 
-Generations findGenerations(Path profile, int & curGen)
+std::pair<Generations, std::optional<GenerationNumber>> findGenerations(Path profile)
 {
     Generations gens;
 
@@ -43,30 +37,34 @@ Generations findGenerations(Path profile, int & curGen)
     auto profileName = std::string(baseNameOf(profile));
 
     for (auto & i : readDirectory(profileDir)) {
-        int n;
-        if ((n = parseName(profileName, i.name)) != -1) {
-            Generation gen;
-            gen.path = profileDir + "/" + i.name;
-            gen.number = n;
+        if (auto n = parseName(profileName, i.name)) {
+            auto path = profileDir + "/" + i.name;
             struct stat st;
-            if (lstat(gen.path.c_str(), &st) != 0)
-                throw SysError("statting '%1%'", gen.path);
-            gen.creationTime = st.st_mtime;
-            gens.push_back(gen);
+            if (lstat(path.c_str(), &st) != 0)
+                throw SysError("statting '%1%'", path);
+            gens.push_back({
+                .number = *n,
+                .path = path,
+                .creationTime = st.st_mtime
+            });
         }
     }
 
-    gens.sort(cmpGensByNumber);
+    gens.sort([](const Generation & a, const Generation & b)
+    {
+        return a.number < b.number;
+    });
 
-    curGen = pathExists(profile)
+    return {
+        gens,
+        pathExists(profile)
         ? parseName(profileName, readLink(profile))
-        : -1;
-
-    return gens;
+        : std::nullopt
+    };
 }
 
 
-static void makeName(const Path & profile, unsigned int num,
+static void makeName(const Path & profile, GenerationNumber num,
     Path & outLink)
 {
     Path prefix = (format("%1%-%2%") % profile % num).str();
@@ -78,10 +76,9 @@ Path createGeneration(ref<LocalFSStore> store, Path profile, Path outPath)
 {
     /* The new generation number should be higher than old the
        previous ones. */
-    int dummy;
-    Generations gens = findGenerations(profile, dummy);
+    auto [gens, dummy] = findGenerations(profile);
 
-    unsigned int num;
+    GenerationNumber num;
     if (gens.size() > 0) {
         Generation last = gens.back();
 
@@ -121,7 +118,7 @@ static void removeFile(const Path & path)
 }
 
 
-void deleteGeneration(const Path & profile, unsigned int gen)
+void deleteGeneration(const Path & profile, GenerationNumber gen)
 {
     Path generation;
     makeName(profile, gen, generation);
@@ -129,7 +126,7 @@ void deleteGeneration(const Path & profile, unsigned int gen)
 }
 
 
-static void deleteGeneration2(const Path & profile, unsigned int gen, bool dryRun)
+static void deleteGeneration2(const Path & profile, GenerationNumber gen, bool dryRun)
 {
     if (dryRun)
         printInfo(format("would remove generation %1%") % gen);
@@ -140,31 +137,29 @@ static void deleteGeneration2(const Path & profile, unsigned int gen, bool dryRu
 }
 
 
-void deleteGenerations(const Path & profile, const std::set<unsigned int> & gensToDelete, bool dryRun)
+void deleteGenerations(const Path & profile, const std::set<GenerationNumber> & gensToDelete, bool dryRun)
 {
     PathLocks lock;
     lockProfile(lock, profile);
 
-    int curGen;
-    Generations gens = findGenerations(profile, curGen);
+    auto [gens, curGen] = findGenerations(profile);
 
-    if (gensToDelete.find(curGen) != gensToDelete.end())
+    if (gensToDelete.count(*curGen))
         throw Error("cannot delete current generation of profile %1%'", profile);
 
     for (auto & i : gens) {
-        if (gensToDelete.find(i.number) == gensToDelete.end()) continue;
+        if (!gensToDelete.count(i.number)) continue;
         deleteGeneration2(profile, i.number, dryRun);
     }
 }
 
-void deleteGenerationsGreaterThan(const Path & profile, int max, bool dryRun)
+void deleteGenerationsGreaterThan(const Path & profile, GenerationNumber max, bool dryRun)
 {
     PathLocks lock;
     lockProfile(lock, profile);
 
-    int curGen;
     bool fromCurGen = false;
-    Generations gens = findGenerations(profile, curGen);
+    auto [gens, curGen] = findGenerations(profile);
     for (auto i = gens.rbegin(); i != gens.rend(); ++i) {
         if (i->number == curGen) {
             fromCurGen = true;
@@ -186,8 +181,7 @@ void deleteOldGenerations(const Path & profile, bool dryRun)
     PathLocks lock;
     lockProfile(lock, profile);
 
-    int curGen;
-    Generations gens = findGenerations(profile, curGen);
+    auto [gens, curGen] = findGenerations(profile);
 
     for (auto & i : gens)
         if (i.number != curGen)
@@ -200,8 +194,7 @@ void deleteGenerationsOlderThan(const Path & profile, time_t t, bool dryRun)
     PathLocks lock;
     lockProfile(lock, profile);
 
-    int curGen;
-    Generations gens = findGenerations(profile, curGen);
+    auto [gens, curGen] = findGenerations(profile);
 
     bool canDelete = false;
     for (auto i = gens.rbegin(); i != gens.rend(); ++i)
diff --git a/src/libstore/profiles.hh b/src/libstore/profiles.hh
index 78645d8b6..abe507f0e 100644
--- a/src/libstore/profiles.hh
+++ b/src/libstore/profiles.hh
@@ -9,37 +9,32 @@
 namespace nix {
 
 
+typedef unsigned int GenerationNumber;
+
 struct Generation
 {
-    int number;
+    GenerationNumber number;
     Path path;
     time_t creationTime;
-    Generation()
-    {
-        number = -1;
-    }
-    operator bool() const
-    {
-        return number != -1;
-    }
 };
 
-typedef list<Generation> Generations;
+typedef std::list<Generation> Generations;
 
 
 /* Returns the list of currently present generations for the specified
-   profile, sorted by generation number. */
-Generations findGenerations(Path profile, int & curGen);
+   profile, sorted by generation number. Also returns the number of
+   the current generation. */
+std::pair<Generations, std::optional<GenerationNumber>> findGenerations(Path profile);
 
 class LocalFSStore;
 
 Path createGeneration(ref<LocalFSStore> store, Path profile, Path outPath);
 
-void deleteGeneration(const Path & profile, unsigned int gen);
+void deleteGeneration(const Path & profile, GenerationNumber gen);
 
-void deleteGenerations(const Path & profile, const std::set<unsigned int> & gensToDelete, bool dryRun);
+void deleteGenerations(const Path & profile, const std::set<GenerationNumber> & gensToDelete, bool dryRun);
 
-void deleteGenerationsGreaterThan(const Path & profile, const int max, bool dryRun);
+void deleteGenerationsGreaterThan(const Path & profile, GenerationNumber max, bool dryRun);
 
 void deleteOldGenerations(const Path & profile, bool dryRun);
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 2fb9c968a..80a10a2bf 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);
     }
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index cbabe3d77..a7288d0cc 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -461,7 +461,7 @@ 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");