Organize content addressing, use SourceAccessor with Store::addToStore

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>

perl/lib/Nix/Store.xs

@@ -13,6 +13,7 @@
 #include "globals.hh"
 #include "store-api.hh"
 #include "crypto.hh"
+#include "posix-source-accessor.hh"
 
 #include <sodium.h>
 #include <nlohmann/json.hpp>
@@ -205,7 +206,10 @@ void importPaths(int fd, int dontCheckSigs)
 SV * hashPath(char * algo, int base32, char * path)
     PPCODE:
         try {
-            Hash h = hashPath(parseHashAlgo(algo), path).first;
+            PosixSourceAccessor accessor;
+            Hash h = hashPath(
+                accessor, CanonPath::fromCwd(path),
+                FileIngestionMethod::Recursive, parseHashAlgo(algo)).first;
             auto s = h.to_string(base32 ? HashFormat::Nix32 : HashFormat::Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
@@ -281,7 +285,11 @@ SV * addToStore(char * srcPath, int recursive, char * algo)
     PPCODE:
         try {
             auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
-            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, method, parseHashAlgo(algo));
+            PosixSourceAccessor accessor;
+            auto path = store()->addToStore(
+                std::string(baseNameOf(srcPath)),
+                accessor, CanonPath::fromCwd(srcPath),
+                method, parseHashAlgo(algo));
             XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());

src/libcmd/installable-value.cc

@@ -44,7 +44,7 @@ ref<InstallableValue> InstallableValue::require(ref<Installable> installable)
 std::optional<DerivedPathWithInfo> InstallableValue::trySinglePathToDerivedPaths(Value & v, const PosIdx pos, std::string_view errorCtx)
 {
     if (v.type() == nPath) {
-        auto storePath = v.path().fetchToStore(state->store);
+        auto storePath = v.path().fetchToStore(*state->store);
         return {{
             .path = DerivedPath::Opaque {
                 .path = std::move(storePath),

src/libexpr/eval.cc

@@ -2317,7 +2317,7 @@ StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePat
     auto dstPath = i != srcToStore.end()
         ? i->second
         : [&]() {
-            auto dstPath = path.fetchToStore(store, path.baseName(), FileIngestionMethod::Recursive, nullptr, repair);
+            auto dstPath = path.fetchToStore(*store, path.baseName(), FileIngestionMethod::Recursive, nullptr, repair);
             allowPath(dstPath);
             srcToStore.insert_or_assign(path, dstPath);
             printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, store->printStorePath(dstPath));

src/libexpr/primops.cc

@@ -2229,7 +2229,7 @@ static void addPath(
             });
 
         if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
-            auto dstPath = path.fetchToStore(state.store, name, method, filter.get(), state.repair);
+            auto dstPath = path.fetchToStore(*state.store, name, method, filter.get(), state.repair);
             if (expectedHash && expectedStorePath != dstPath)
                 state.debugThrowLastTrace(Error("store path mismatch in (possibly filtered) path added from '%s'", path));
             state.allowAndSetStorePathString(dstPath, v);

src/libfetchers/cache.cc

@@ -106,7 +106,7 @@ struct CacheImpl : Cache
     }
 
     void add(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs,
         const Attrs & infoAttrs,
         const StorePath & storePath,
@@ -115,13 +115,13 @@ struct CacheImpl : Cache
         _state.lock()->add.use()
             (attrsToJSON(inAttrs).dump())
             (attrsToJSON(infoAttrs).dump())
-            (store->printStorePath(storePath))
+            (store.printStorePath(storePath))
             (locked)
             (time(0)).exec();
     }
 
     std::optional<std::pair<Attrs, StorePath>> lookup(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs) override
     {
         if (auto res = lookupExpired(store, inAttrs)) {
@@ -134,7 +134,7 @@ struct CacheImpl : Cache
     }
 
     std::optional<Result> lookupExpired(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs) override
     {
         auto state(_state.lock());
@@ -148,19 +148,19 @@ struct CacheImpl : Cache
         }
 
         auto infoJSON = stmt.getStr(0);
-        auto storePath = store->parseStorePath(stmt.getStr(1));
+        auto storePath = store.parseStorePath(stmt.getStr(1));
         auto locked = stmt.getInt(2) != 0;
         auto timestamp = stmt.getInt(3);
 
-        store->addTempRoot(storePath);
+        store.addTempRoot(storePath);
-        if (!store->isValidPath(storePath)) {
+        if (!store.isValidPath(storePath)) {
             // FIXME: we could try to substitute 'storePath'.
             debug("ignoring disappeared cache entry '%s'", inAttrsJSON);
             return {};
         }
 
         debug("using cache entry '%s' -> '%s', '%s'",
-            inAttrsJSON, infoJSON, store->printStorePath(storePath));
+            inAttrsJSON, infoJSON, store.printStorePath(storePath));
 
         return Result {
             .expired = !locked && (settings.tarballTtl.get() == 0 || timestamp + settings.tarballTtl < time(0)),

src/libfetchers/cache.hh

@@ -50,14 +50,14 @@ struct Cache
 
     /* Old cache for things that have a store path. */
     virtual void add(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs,
         const Attrs & infoAttrs,
         const StorePath & storePath,
         bool locked) = 0;
 
     virtual std::optional<std::pair<Attrs, StorePath>> lookup(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs) = 0;
 
     struct Result
@@ -68,7 +68,7 @@ struct Cache
     };
 
     virtual std::optional<Result> lookupExpired(
-        ref<Store> store,
+        Store & store,
         const Attrs & inAttrs) = 0;
 };
 

src/libfetchers/fetchers.cc

@@ -374,7 +374,7 @@ void InputScheme::clone(const Input & input, const Path & destDir) const
 std::pair<StorePath, Input> InputScheme::fetch(ref<Store> store, const Input & input)
 {
     auto [accessor, input2] = getAccessor(store, input);
-    auto storePath = SourcePath(accessor).fetchToStore(store, input2.getName());
+    auto storePath = SourcePath(accessor).fetchToStore(*store, input2.getName());
     return {storePath, input2};
 }
 

src/libfetchers/git.cc

@@ -368,14 +368,14 @@ struct GitInputScheme : InputScheme
 
     RepoInfo getRepoInfo(const Input & input) const
     {
-        auto checkHashType = [&](const std::optional<Hash> & hash)
+        auto checkHashAlgorithm = [&](const std::optional<Hash> & hash)
         {
             if (hash.has_value() && !(hash->algo == HashAlgorithm::SHA1 || hash->algo == HashAlgorithm::SHA256))
                 throw Error("Hash '%s' is not supported by Git. Supported types are sha1 and sha256.", hash->to_string(HashFormat::Base16, true));
         };
 
         if (auto rev = input.getRev())
-            checkHashType(rev);
+            checkHashAlgorithm(rev);
 
         RepoInfo repoInfo;
 

src/libfetchers/github.cc

@@ -201,7 +201,7 @@ struct GitArchiveInputScheme : InputScheme
             {"rev", rev->gitRev()},
         });
 
-        if (auto res = getCache()->lookup(store, lockedAttrs)) {
+        if (auto res = getCache()->lookup(*store, lockedAttrs)) {
             input.attrs.insert_or_assign("lastModified", getIntAttr(res->first, "lastModified"));
             return {std::move(res->second), input};
         }
@@ -213,7 +213,7 @@ struct GitArchiveInputScheme : InputScheme
         input.attrs.insert_or_assign("lastModified", uint64_t(result.lastModified));
 
         getCache()->add(
-            store,
+            *store,
             lockedAttrs,
             {
                 {"rev", rev->gitRev()},

src/libfetchers/input-accessor.cc

@@ -5,10 +5,10 @@
 namespace nix {
 
 StorePath InputAccessor::fetchToStore(
-    ref<Store> store,
+    Store & store,
     const CanonPath & path,
     std::string_view name,
-    FileIngestionMethod method,
+    ContentAddressMethod method,
     PathFilter * filter,
     RepairFlag repair)
 {
@@ -20,10 +20,24 @@ StorePath InputAccessor::fetchToStore(
     if (!filter && fingerprint) {
         cacheKey = fetchers::Attrs{
             {"_what", "fetchToStore"},
-            {"store", store->storeDir},
+            {"store", store.storeDir},
             {"name", std::string(name)},
             {"fingerprint", *fingerprint},
-            {"method", (uint8_t) method},
+            {
+                "method",
+                std::visit(overloaded {
+                    [](const TextIngestionMethod &) {
+                        return "text";
+                    },
+                    [](const FileIngestionMethod & fim) {
+                        switch (fim) {
+                        case FileIngestionMethod::Flat: return "flat";
+                        case FileIngestionMethod::Recursive: return "nar";
+                        default: assert(false);
+                        }
+                    },
+                }, method.raw),
+            },
             {"path", path.abs()}
         };
         if (auto res = fetchers::getCache()->lookup(store, *cacheKey)) {
@@ -35,17 +49,14 @@ StorePath InputAccessor::fetchToStore(
 
     Activity act(*logger, lvlChatty, actUnknown, fmt("copying '%s' to the store", showPath(path)));
 
-    auto source = sinkToSource([&](Sink & sink) {
+    auto filter2 = filter ? *filter : defaultPathFilter;
-        if (method == FileIngestionMethod::Recursive)
-            dumpPath(path, sink, filter ? *filter : defaultPathFilter);
-        else
-            readFile(path, sink);
-    });
 
     auto storePath =
         settings.readOnlyMode
-        ? store->computeStorePathFromDump(*source, name, method, HashAlgorithm::SHA256).first
+        ? store.computeStorePath(
-        : store->addToStoreFromDump(*source, name, method, HashAlgorithm::SHA256, repair);
+            name, *this, path, method, HashAlgorithm::SHA256, {}, filter2).first
+        : store.addToStore(
+            name, *this, path, method, HashAlgorithm::SHA256, {}, filter2, repair);
 
     if (cacheKey)
         fetchers::getCache()->add(store, *cacheKey, {}, storePath, true);
@@ -60,9 +71,9 @@ std::ostream & operator << (std::ostream & str, const SourcePath & path)
 }
 
 StorePath SourcePath::fetchToStore(
-    ref<Store> store,
+    Store & store,
     std::string_view name,
-    FileIngestionMethod method,
+    ContentAddressMethod method,
     PathFilter * filter,
     RepairFlag repair) const
 {

src/libfetchers/input-accessor.hh

@@ -30,10 +30,10 @@ struct InputAccessor : virtual SourceAccessor, std::enable_shared_from_this<Inpu
     }
 
     StorePath fetchToStore(
-        ref<Store> store,
+        Store & store,
         const CanonPath & path,
         std::string_view name = "source",
-        FileIngestionMethod method = FileIngestionMethod::Recursive,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
         PathFilter * filter = nullptr,
         RepairFlag repair = NoRepair);
 };
@@ -116,9 +116,9 @@ struct SourcePath
      * Copy this `SourcePath` to the Nix store.
      */
     StorePath fetchToStore(
-        ref<Store> store,
+        Store & store,
         std::string_view name = "source",
-        FileIngestionMethod method = FileIngestionMethod::Recursive,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
         PathFilter * filter = nullptr,
         RepairFlag repair = NoRepair) const;
 

src/libfetchers/mercurial.cc

@@ -6,6 +6,7 @@
 #include "tarfile.hh"
 #include "store-api.hh"
 #include "url-parts.hh"
+#include "posix-source-accessor.hh"
 
 #include "fetch-settings.hh"
 
@@ -210,7 +211,12 @@ struct MercurialInputScheme : InputScheme
                     return files.count(file);
                 };
 
-                auto storePath = store->addToStore(input.getName(), actualPath, FileIngestionMethod::Recursive, HashAlgorithm::SHA256, filter);
+                PosixSourceAccessor accessor;
+                auto storePath = store->addToStore(
+                    input.getName(),
+                    accessor, CanonPath { actualPath },
+                    FileIngestionMethod::Recursive, HashAlgorithm::SHA256, {},
+                    filter);
 
                 return {std::move(storePath), input};
             }
@@ -218,7 +224,7 @@ struct MercurialInputScheme : InputScheme
 
         if (!input.getRef()) input.attrs.insert_or_assign("ref", "default");
 
-        auto checkHashType = [&](const std::optional<Hash> & hash)
+        auto checkHashAlgorithm = [&](const std::optional<Hash> & hash)
         {
             if (hash.has_value() && hash->algo != HashAlgorithm::SHA1)
                 throw Error("Hash '%s' is not supported by Mercurial. Only sha1 is supported.", hash->to_string(HashFormat::Base16, true));
@@ -227,7 +233,7 @@ struct MercurialInputScheme : InputScheme
 
         auto getLockedAttrs = [&]()
         {
-            checkHashType(input.getRev());
+            checkHashAlgorithm(input.getRev());
 
             return Attrs({
                 {"type", "hg"},
@@ -246,7 +252,7 @@ struct MercurialInputScheme : InputScheme
         };
 
         if (input.getRev()) {
-            if (auto res = getCache()->lookup(store, getLockedAttrs()))
+            if (auto res = getCache()->lookup(*store, getLockedAttrs()))
                 return makeResult(res->first, std::move(res->second));
         }
 
@@ -259,7 +265,7 @@ struct MercurialInputScheme : InputScheme
             {"ref", *input.getRef()},
         });
 
-        if (auto res = getCache()->lookup(store, unlockedAttrs)) {
+        if (auto res = getCache()->lookup(*store, unlockedAttrs)) {
             auto rev2 = Hash::parseAny(getStrAttr(res->first, "rev"), HashAlgorithm::SHA1);
             if (!input.getRev() || input.getRev() == rev2) {
                 input.attrs.insert_or_assign("rev", rev2.gitRev());
@@ -305,7 +311,7 @@ struct MercurialInputScheme : InputScheme
         auto revCount = std::stoull(tokens[1]);
         input.attrs.insert_or_assign("ref", tokens[2]);
 
-        if (auto res = getCache()->lookup(store, getLockedAttrs()))
+        if (auto res = getCache()->lookup(*store, getLockedAttrs()))
             return makeResult(res->first, std::move(res->second));
 
         Path tmpDir = createTempDir();
@@ -315,7 +321,8 @@ struct MercurialInputScheme : InputScheme
 
         deletePath(tmpDir + "/.hg_archival.txt");
 
-        auto storePath = store->addToStore(name, tmpDir);
+        PosixSourceAccessor accessor;
+        auto storePath = store->addToStore(name, accessor, CanonPath { tmpDir });
 
         Attrs infoAttrs({
             {"rev", input.getRev()->gitRev()},
@@ -324,14 +331,14 @@ struct MercurialInputScheme : InputScheme
 
         if (!_input.getRev())
             getCache()->add(
-                store,
+                *store,
                 unlockedAttrs,
                 infoAttrs,
                 storePath,
                 false);
 
         getCache()->add(
-            store,
+            *store,
             getLockedAttrs(),
             infoAttrs,
             storePath,

src/libfetchers/tarball.cc

@@ -8,6 +8,7 @@
 #include "tarfile.hh"
 #include "types.hh"
 #include "split.hh"
+#include "posix-source-accessor.hh"
 
 namespace nix::fetchers {
 
@@ -26,7 +27,7 @@ DownloadFileResult downloadFile(
         {"name", name},
     });
 
-    auto cached = getCache()->lookupExpired(store, inAttrs);
+    auto cached = getCache()->lookupExpired(*store, inAttrs);
 
     auto useCached = [&]() -> DownloadFileResult
     {
@@ -91,7 +92,7 @@ DownloadFileResult downloadFile(
     }
 
     getCache()->add(
-        store,
+        *store,
         inAttrs,
         infoAttrs,
         *storePath,
@@ -99,7 +100,7 @@ DownloadFileResult downloadFile(
 
     if (url != res.effectiveUri)
         getCache()->add(
-            store,
+            *store,
             {
                 {"type", "file"},
                 {"url", res.effectiveUri},
@@ -130,7 +131,7 @@ DownloadTarballResult downloadTarball(
         {"name", name},
     });
 
-    auto cached = getCache()->lookupExpired(store, inAttrs);
+    auto cached = getCache()->lookupExpired(*store, inAttrs);
 
     if (cached && !cached->expired)
         return {
@@ -156,7 +157,8 @@ DownloadTarballResult downloadTarball(
             throw nix::Error("tarball '%s' contains an unexpected number of top-level files", url);
         auto topDir = tmpDir + "/" + members.begin()->name;
         lastModified = lstat(topDir).st_mtime;
-        unpackedStorePath = store->addToStore(name, topDir, FileIngestionMethod::Recursive, HashAlgorithm::SHA256, defaultPathFilter, NoRepair);
+        PosixSourceAccessor accessor;
+        unpackedStorePath = store->addToStore(name, accessor, CanonPath { topDir }, FileIngestionMethod::Recursive, HashAlgorithm::SHA256, {}, defaultPathFilter, NoRepair);
     }
 
     Attrs infoAttrs({
@@ -168,7 +170,7 @@ DownloadTarballResult downloadTarball(
         infoAttrs.emplace("immutableUrl", *res.immutableUrl);
 
     getCache()->add(
-        store,
+        *store,
         inAttrs,
         infoAttrs,
         *unpackedStorePath,

src/libstore/binary-cache-store.cc

@@ -300,8 +300,13 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
     }});
 }
 
-StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view name,
+StorePath BinaryCacheStore::addToStoreFromDump(
-                                               FileIngestionMethod method, HashAlgorithm hashAlgo, RepairFlag repair, const StorePathSet & references)
+    Source & dump,
+    std::string_view name,
+    ContentAddressMethod method,
+    HashAlgorithm hashAlgo,
+    const StorePathSet & references,
+    RepairFlag repair)
 {
     if (method != FileIngestionMethod::Recursive || hashAlgo != HashAlgorithm::SHA256)
         unsupported("addToStoreFromDump");
@@ -309,15 +314,14 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view n
         ValidPathInfo info {
             *this,
             name,
-            FixedOutputInfo {
+            ContentAddressWithReferences::fromParts(
-                .method = method,
+                method,
-                .hash = nar.first,
+                nar.first,
-                .references = {
+                {
                     .others = references,
                     // caller is not capable of creating a self-reference, because this is content-addressed without modulus
                     .self = false,
-                },
+                }),
-            },
             nar.first,
         };
         info.narSize = nar.second;
@@ -400,41 +404,35 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
 
 StorePath BinaryCacheStore::addToStore(
     std::string_view name,
-        const Path & srcPath,
+    SourceAccessor & accessor,
-        FileIngestionMethod method,
+    const CanonPath & path,
+    ContentAddressMethod method,
     HashAlgorithm hashAlgo,
+    const StorePathSet & references,
     PathFilter & filter,
-        RepairFlag repair,
+    RepairFlag repair)
-        const StorePathSet & references)
 {
     /* FIXME: Make BinaryCacheStore::addToStoreCommon support
        non-recursive+sha256 so we can just use the default
        implementation of this method in terms of addToStoreFromDump. */
 
-    HashSink sink { hashAlgo };
+    auto h = hashPath(accessor, path, method.getFileIngestionMethod(), hashAlgo, filter).first;
-    if (method == FileIngestionMethod::Recursive) {
-        dumpPath(srcPath, sink, filter);
-    } else {
-        readFile(srcPath, sink);
-    }
-    auto h = sink.finish().first;
 
     auto source = sinkToSource([&](Sink & sink) {
-        dumpPath(srcPath, sink, filter);
+        accessor.dumpPath(path, sink, filter);
     });
     return addToStoreCommon(*source, repair, CheckSigs, [&](HashResult nar) {
         ValidPathInfo info {
             *this,
             name,
-            FixedOutputInfo {
+            ContentAddressWithReferences::fromParts(
-                .method = method,
+                method,
-                .hash = h,
+                h,
-                .references = {
+                {
                     .others = references,
                     // caller is not capable of creating a self-reference, because this is content-addressed without modulus
                     .self = false,
-                },
+                }),
-            },
             nar.first,
         };
         info.narSize = nar.second;

src/libstore/binary-cache-store.hh

@@ -123,17 +123,23 @@ public:
     void addToStore(const ValidPathInfo & info, Source & narSource,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
-    StorePath addToStoreFromDump(Source & dump, std::string_view name,
+    StorePath addToStoreFromDump(
-                                 FileIngestionMethod method, HashAlgorithm hashAlgo, RepairFlag repair, const StorePathSet & references) override;
+        Source & dump,
+        std::string_view name,
+        ContentAddressMethod method,
+        HashAlgorithm hashAlgo,
+        const StorePathSet & references,
+        RepairFlag repair) override;
 
     StorePath addToStore(
         std::string_view name,
-            const Path & srcPath,
+        SourceAccessor & accessor,
-            FileIngestionMethod method,
+        const CanonPath & srcPath,
+        ContentAddressMethod method,
         HashAlgorithm hashAlgo,
+        const StorePathSet & references,
         PathFilter & filter,
-            RepairFlag repair,
+        RepairFlag repair) override;
-            const StorePathSet & references) override;
 
     StorePath addTextToStore(
         std::string_view name,

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

@@ -20,6 +20,7 @@
 #include "child.hh"
 #include "unix-domain-socket.hh"
 #include "posix-fs-canonicalise.hh"
+#include "posix-source-accessor.hh"
 
 #include <regex>
 #include <queue>
@@ -1291,12 +1292,13 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual In
 
     StorePath addToStore(
         std::string_view name,
-            const Path & srcPath,
+        SourceAccessor & accessor,
-            FileIngestionMethod method,
+        const CanonPath & srcPath,
+        ContentAddressMethod method,
         HashAlgorithm hashAlgo,
+        const StorePathSet & references,
         PathFilter & filter,
-            RepairFlag repair,
+        RepairFlag repair) override
-            const StorePathSet & references) override
     { throw Error("addToStore"); }
 
     void addToStore(const ValidPathInfo & info, Source & narSource,
@@ -1320,12 +1322,12 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual In
     StorePath addToStoreFromDump(
         Source & dump,
         std::string_view name,
-            FileIngestionMethod method,
+        ContentAddressMethod method,
         HashAlgorithm hashAlgo,
-            RepairFlag repair,
+        const StorePathSet & references,
-            const StorePathSet & references) override
+        RepairFlag repair) override
     {
-        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair, references);
+        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, references, repair);
         goal.addDependency(path);
         return path;
     }
@@ -2453,8 +2455,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                 throw BuildError(
                     "output path %1% without valid stats info",
                     actualPath);
-            if (outputHash.method == ContentAddressMethod { FileIngestionMethod::Flat } ||
+            if (outputHash.method.getFileIngestionMethod() == FileIngestionMethod::Flat)
-                outputHash.method == ContentAddressMethod { TextIngestionMethod {} })
             {
                 /* The output path should be a regular file without execute permission. */
                 if (!S_ISREG(st->st_mode) || (st->st_mode & S_IXUSR) != 0)
@@ -2466,38 +2467,23 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
             rewriteOutput(outputRewrites);
             /* FIXME optimize and deduplicate with addToStore */
             std::string oldHashPart { scratchPath->hashPart() };
+            auto got = ({
                 HashModuloSink caSink { outputHash.hashAlgo, oldHashPart };
-            std::visit(overloaded {
+                PosixSourceAccessor accessor;
-                [&](const TextIngestionMethod &) {
+                dumpPath(
-                    readFile(actualPath, caSink);
+                    accessor, CanonPath { actualPath },
-                },
+                    caSink,
-                [&](const FileIngestionMethod & m2) {
+                    outputHash.method.getFileIngestionMethod());
-                    switch (m2) {
+                caSink.finish().first;
-                    case FileIngestionMethod::Recursive:
+            });
-                        dumpPath(actualPath, caSink);
-                        break;
-                    case FileIngestionMethod::Flat:
-                        readFile(actualPath, caSink);
-                        break;
-                    }
-                },
-            }, outputHash.method.raw);
-            auto got = caSink.finish().first;
 
-            auto optCA = ContentAddressWithReferences::fromPartsOpt(
-                outputHash.method,
-                std::move(got),
-                rewriteRefs());
-            if (!optCA) {
-                // TODO track distinct failure modes separately (at the time of
-                // writing there is just one but `nullopt` is unclear) so this
-                // message can't get out of sync.
-                throw BuildError("output path '%s' has illegal content address, probably a spurious self-reference with text hashing");
-            }
             ValidPathInfo newInfo0 {
                 worker.store,
                 outputPathName(drv->name, outputName),
-                std::move(*optCA),
+                ContentAddressWithReferences::fromParts(
+                    outputHash.method,
+                    std::move(got),
+                    rewriteRefs()),
                 Hash::dummy,
             };
             if (*scratchPath != newInfo0.path) {
@@ -2511,9 +2497,14 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                                std::string(newInfo0.path.hashPart())}});
             }
 
-            HashResult narHashAndSize = hashPath(HashAlgorithm::SHA256, actualPath);
+            {
+                PosixSourceAccessor accessor;
+                HashResult narHashAndSize = hashPath(
+                    accessor, CanonPath { actualPath },
+                    FileIngestionMethod::Recursive, HashAlgorithm::SHA256);
                 newInfo0.narHash = narHashAndSize.first;
                 newInfo0.narSize = narHashAndSize.second;
+            }
 
             assert(newInfo0.ca);
             return newInfo0;
@@ -2531,7 +2522,10 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                         std::string { scratchPath->hashPart() },
                         std::string { requiredFinalPath.hashPart() });
                 rewriteOutput(outputRewrites);
-                auto narHashAndSize = hashPath(HashAlgorithm::SHA256, actualPath);
+                PosixSourceAccessor accessor;
+                HashResult narHashAndSize = hashPath(
+                    accessor, CanonPath { actualPath },
+                    FileIngestionMethod::Recursive, HashAlgorithm::SHA256);
                 ValidPathInfo newInfo0 { requiredFinalPath, narHashAndSize.first };
                 newInfo0.narSize = narHashAndSize.second;
                 auto refs = rewriteRefs();

src/libstore/build/worker.cc

@@ -519,7 +519,9 @@ bool Worker::pathContentsGood(const StorePath & path)
     if (!pathExists(store.printStorePath(path)))
         res = false;
     else {
-        HashResult current = hashPath(info->narHash.algo, store.printStorePath(path));
+        HashResult current = hashPath(
+            *store.getFSAccessor(), CanonPath { store.printStorePath(path) },
+            FileIngestionMethod::Recursive, info->narHash.algo);
         Hash nullHash(HashAlgorithm::SHA256);
         res = info->narHash == nullHash || info->narHash == current.first;
     }

src/libstore/content-address.cc

@@ -50,6 +50,18 @@ std::string ContentAddressMethod::render(HashAlgorithm ha) const
     }, raw);
 }
 
+FileIngestionMethod ContentAddressMethod::getFileIngestionMethod() const
+{
+    return std::visit(overloaded {
+        [&](const TextIngestionMethod & th) {
+            return FileIngestionMethod::Flat;
+        },
+        [&](const FileIngestionMethod & fim) {
+            return fim;
+        }
+    }, raw);
+}
+
 std::string ContentAddress::render() const
 {
     return std::visit(overloaded {
@@ -79,7 +91,7 @@ static std::pair<ContentAddressMethod, HashAlgorithm> parseContentAddressMethodP
         prefix = *optPrefix;
     }
 
-    auto parseHashType_ = [&](){
+    auto parseHashAlgorithm_ = [&](){
         auto hashTypeRaw = splitPrefixTo(rest, ':');
         if (!hashTypeRaw)
             throw UsageError("content address hash must be in form '<algo>:<hash>', but found: %s", wholeInput);
@@ -90,7 +102,7 @@ static std::pair<ContentAddressMethod, HashAlgorithm> parseContentAddressMethodP
     // Switch on prefix
     if (prefix == "text") {
         // No parsing of the ingestion method, "text" only support flat.
-        HashAlgorithm hashAlgo = parseHashType_();
+        HashAlgorithm hashAlgo = parseHashAlgorithm_();
         return {
             TextIngestionMethod {},
             std::move(hashAlgo),
@@ -100,7 +112,7 @@ static std::pair<ContentAddressMethod, HashAlgorithm> parseContentAddressMethodP
         auto method = FileIngestionMethod::Flat;
         if (splitPrefix(rest, "r:"))
             method = FileIngestionMethod::Recursive;
-        HashAlgorithm hashAlgo = parseHashType_();
+        HashAlgorithm hashAlgo = parseHashAlgorithm_();
         return {
             std::move(method),
             std::move(hashAlgo),
@@ -176,13 +188,13 @@ ContentAddressWithReferences ContentAddressWithReferences::withoutRefs(const Con
     }, ca.method.raw);
 }
 
-std::optional<ContentAddressWithReferences> ContentAddressWithReferences::fromPartsOpt(
+ContentAddressWithReferences ContentAddressWithReferences::fromParts(
-    ContentAddressMethod method, Hash hash, StoreReferences refs) noexcept
+    ContentAddressMethod method, Hash hash, StoreReferences refs)
 {
     return std::visit(overloaded {
-        [&](TextIngestionMethod _) -> std::optional<ContentAddressWithReferences> {
+        [&](TextIngestionMethod _) -> ContentAddressWithReferences {
             if (refs.self)
-                return std::nullopt;
+                throw Error("self-reference not allowed with text hashing");
             return ContentAddressWithReferences {
                 TextInfo {
                     .hash = std::move(hash),
@@ -190,7 +202,7 @@ std::optional<ContentAddressWithReferences> ContentAddressWithReferences::fromPa
                 }
             };
         },
-        [&](FileIngestionMethod m2) -> std::optional<ContentAddressWithReferences> {
+        [&](FileIngestionMethod m2) -> ContentAddressWithReferences {
             return ContentAddressWithReferences {
                 FixedOutputInfo {
                     .method = m2,

src/libstore/content-address.hh

@@ -4,6 +4,7 @@
 #include <variant>
 #include "hash.hh"
 #include "path.hh"
+#include "file-content-address.hh"
 #include "comparator.hh"
 #include "variant-wrapper.hh"
 
@@ -31,22 +32,6 @@ namespace nix {
  */
 struct TextIngestionMethod : std::monostate { };
 
-/**
- * An enumeration of the main ways we can serialize file system
- * objects.
- */
-enum struct FileIngestionMethod : uint8_t {
-    /**
-     * Flat-file hashing. Directly ingest the contents of a single file
-     */
-    Flat = 0,
-    /**
-     * Recursive (or NAR) hashing. Serializes the file-system object in Nix
-     * Archive format and ingest that
-     */
-    Recursive = 1
-};
-
 /**
  * Compute the prefix to the hash algorithm which indicates how the
  * files were ingested.
@@ -54,7 +39,7 @@ enum struct FileIngestionMethod : uint8_t {
 std::string makeFileIngestionPrefix(FileIngestionMethod m);
 
 /**
- * An enumeration of all the ways we can serialize file system objects.
+ * An enumeration of all the ways we can content-address store objects.
  *
  * Just the type of a content address. Combine with the hash itself, and
  * we have a `ContentAddress` as defined below. Combine that, in turn,
@@ -102,7 +87,15 @@ struct ContentAddressMethod
      *
      * The rough inverse of `parse()`.
      */
-    std::string render(HashAlgorithm ha) const;
+    std::string render(HashAlgorithm ht) const;
+
+    /**
+     * Get the underlying way to content-address file system objects.
+     *
+     * Different ways of hashing store objects may use the same method
+     * for hashing file systeme objects.
+     */
+    FileIngestionMethod getFileIngestionMethod() const;
 };
 
 
@@ -266,11 +259,12 @@ struct ContentAddressWithReferences
      *
      * @param refs References to other store objects or oneself.
      *
-     * Do note that not all combinations are supported; `nullopt` is
+     * @note note that all combinations are supported. This is a
-     * returns for invalid combinations.
+     * *partial function* and exceptions will be thrown for invalid
+     * combinations.
      */
-    static std::optional<ContentAddressWithReferences> fromPartsOpt(
+    static ContentAddressWithReferences fromParts(
-        ContentAddressMethod method, Hash hash, StoreReferences refs) noexcept;
+        ContentAddressMethod method, Hash hash, StoreReferences refs);
 
     ContentAddressMethod getMethod() const;
 

src/libstore/daemon.cc

@@ -403,22 +403,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                 auto [contentAddressMethod, hashAlgo_] = ContentAddressMethod::parse(camStr);
                 auto hashAlgo = hashAlgo_; // work around clang bug
                 FramedSource source(from);
-                // TODO this is essentially RemoteStore::addCAToStore. Move it up to Store.
+                // TODO these two steps are essentially RemoteStore::addCAToStore. Move it up to Store.
-                return std::visit(overloaded {
+                auto path = store->addToStoreFromDump(source, name, contentAddressMethod, hashAlgo, refs, repair);
-                    [&](const TextIngestionMethod &) {
-                        if (hashAlgo != HashAlgorithm::SHA256)
-                            throw UnimplementedError("When adding text-hashed data called '%s', only SHA-256 is supported but '%s' was given",
-                                name, printHashAlgo(hashAlgo));
-                        // We could stream this by changing Store
-                        std::string contents = source.drain();
-                        auto path = store->addTextToStore(name, contents, refs, repair);
                 return store->queryPathInfo(path);
-                    },
-                    [&](const FileIngestionMethod & fim) {
-                        auto path = store->addToStoreFromDump(source, name, fim, hashAlgo, repair, refs);
-                        return store->queryPathInfo(path);
-                    },
-                }, contentAddressMethod.raw);
             }();
             logger->stopWork();
 

src/libstore/legacy-ssh-store.hh

@@ -60,12 +60,13 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
 
     StorePath addToStore(
         std::string_view name,
-            const Path & srcPath,
+        SourceAccessor & accessor,
-            FileIngestionMethod method,
+        const CanonPath & srcPath,
+        ContentAddressMethod method,
         HashAlgorithm hashAlgo,
+        const StorePathSet & references,
         PathFilter & filter,
-            RepairFlag repair,
+        RepairFlag repair) override
-            const StorePathSet & references) override
     { unsupported("addToStore"); }
 
     StorePath addTextToStore(

src/libstore/local-store.cc

@@ -13,6 +13,7 @@
 #include "compression.hh"
 #include "signals.hh"
 #include "posix-fs-canonicalise.hh"
+#include "posix-source-accessor.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -1088,11 +1089,22 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
             if (info.ca) {
                 auto & specified = *info.ca;
-                auto actualHash = hashCAPath(
+                auto actualHash = ({
-                    specified.method,
+                    HashModuloSink caSink {
                         specified.hash.algo,
-                    info.path
+                        std::string { info.path.hashPart() },
-                );
+                    };
+                    PosixSourceAccessor accessor;
+                    dumpPath(
+                        *getFSAccessor(false),
+                        CanonPath { printStorePath(info.path) },
+                        caSink,
+                        specified.method.getFileIngestionMethod());
+                    ContentAddress {
+                        .method = specified.method,
+                        .hash = caSink.finish().first,
+                    };
+                });
                 if (specified.hash != actualHash.hash) {
                     throw Error("ca hash mismatch importing path '%s';\n  specified: %s\n  got:       %s",
                         printStorePath(info.path),
@@ -1115,8 +1127,13 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 }
 
 
-StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name,
+StorePath LocalStore::addToStoreFromDump(
-                                         FileIngestionMethod method, HashAlgorithm hashAlgo, RepairFlag repair, const StorePathSet & references)
+    Source & source0,
+    std::string_view name,
+    ContentAddressMethod method,
+    HashAlgorithm hashAlgo,
+    const StorePathSet & references,
+    RepairFlag repair)
 {
     /* For computing the store path. */
     auto hashSink = std::make_unique<HashSink>(hashAlgo);
@@ -1166,25 +1183,21 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
         delTempDir = std::make_unique<AutoDelete>(tempDir);
         tempPath = tempDir + "/x";
 
-        if (method == FileIngestionMethod::Recursive)
+        restorePath(tempPath, bothSource, method.getFileIngestionMethod());
-            restorePath(tempPath, bothSource);
-        else
-            writeFile(tempPath, bothSource);
 
         dump.clear();
     }
 
     auto [hash, size] = hashSink->finish();
 
-    ContentAddressWithReferences desc = FixedOutputInfo {
+    auto desc = ContentAddressWithReferences::fromParts(
-        .method = method,
+        method,
-        .hash = hash,
+        hash,
-        .references = {
+        {
             .others = references,
             // caller is not capable of creating a self-reference, because this is content-addressed without modulus
             .self = false,
-        },
+        });
-    };
 
     auto dstPath = makeFixedOutputPathFromCA(name, desc);
 
@@ -1207,11 +1220,8 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
 
             if (inMemory) {
                 StringSource dumpSource { dump };
-                /* Restore from the NAR in memory. */
+                /* Restore from the buffer in memory. */
-                if (method == FileIngestionMethod::Recursive)
+                restorePath(realPath, dumpSource, method.getFileIngestionMethod());
-                    restorePath(realPath, dumpSource);
-                else
-                    writeFile(realPath, dumpSource);
             } else {
                 /* Move the temporary path we restored above. */
                 moveFile(tempPath, realPath);
@@ -1389,7 +1399,10 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
         for (auto & link : readDirectory(linksDir)) {
             printMsg(lvlTalkative, "checking contents of '%s'", link.name);
             Path linkPath = linksDir + "/" + link.name;
-            std::string hash = hashPath(HashAlgorithm::SHA256, linkPath).first.to_string(HashFormat::Nix32, false);
+            PosixSourceAccessor accessor;
+            std::string hash = hashPath(
+                accessor, CanonPath { linkPath },
+                FileIngestionMethod::Recursive, HashAlgorithm::SHA256).first.to_string(HashFormat::Nix32, false);
             if (hash != link.name) {
                 printError("link '%s' was modified! expected hash '%s', got '%s'",
                     linkPath, link.name, hash);
@@ -1696,42 +1709,6 @@ void LocalStore::queryRealisationUncached(const DrvOutput & id,
     }
 }
 
-ContentAddress LocalStore::hashCAPath(
-    const ContentAddressMethod & method, const HashAlgorithm & hashAlgo,
-    const StorePath & path)
-{
-    return hashCAPath(method, hashAlgo, Store::toRealPath(path), path.hashPart());
-}
-
-ContentAddress LocalStore::hashCAPath(
-    const ContentAddressMethod & method,
-    const HashAlgorithm & hashAlgo,
-    const Path & path,
-    const std::string_view pathHash
-)
-{
-    HashModuloSink caSink ( hashAlgo, std::string(pathHash) );
-    std::visit(overloaded {
-        [&](const TextIngestionMethod &) {
-            readFile(path, caSink);
-        },
-        [&](const FileIngestionMethod & m2) {
-            switch (m2) {
-            case FileIngestionMethod::Recursive:
-                dumpPath(path, caSink);
-                break;
-            case FileIngestionMethod::Flat:
-                readFile(path, caSink);
-                break;
-            }
-        },
-    }, method.raw);
-    return ContentAddress {
-        .method = method,
-        .hash = caSink.finish().first,
-    };
-}
-
 void LocalStore::addBuildLog(const StorePath & drvPath, std::string_view log)
 {
     assert(drvPath.isDerivation());

src/libstore/local-store.hh

@@ -177,8 +177,13 @@ public:
     void addToStore(const ValidPathInfo & info, Source & source,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
-    StorePath addToStoreFromDump(Source & dump, std::string_view name,
+    StorePath addToStoreFromDump(
-                                 FileIngestionMethod method, HashAlgorithm hashAlgo, RepairFlag repair, const StorePathSet & references) override;
+        Source & dump,
+        std::string_view name,
+        ContentAddressMethod method,
+        HashAlgorithm hashAlgo,
+        const StorePathSet & references,
+        RepairFlag repair) override;
 
     StorePath addTextToStore(
         std::string_view name,
@@ -350,19 +355,6 @@ private:
     void signPathInfo(ValidPathInfo & info);
     void signRealisation(Realisation &);
 
-    // XXX: Make a generic `Store` method
-    ContentAddress hashCAPath(
-        const ContentAddressMethod & method,
-        const HashAlgorithm & hashAlgo,
-        const StorePath & path);
-
-    ContentAddress hashCAPath(
-        const ContentAddressMethod & method,
-        const HashAlgorithm & hashAlgo,
-        const Path & path,
-        const std::string_view pathHash
-    );
-
     void addBuildLog(const StorePath & drvPath, std::string_view log) override;
 
     friend struct LocalDerivationGoal;

src/libstore/optimise-store.cc

@@ -2,6 +2,7 @@
 #include "globals.hh"
 #include "signals.hh"
 #include "posix-fs-canonicalise.hh"
+#include "posix-source-accessor.hh"
 
 #include <cstdlib>
 #include <cstring>
@@ -146,7 +147,12 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
        Also note that if `path' is a symlink, then we're hashing the
        contents of the symlink (i.e. the result of readlink()), not
        the contents of the target (which may not even exist). */
-    Hash hash = hashPath(HashAlgorithm::SHA256, path).first;
+    Hash hash = ({
+        PosixSourceAccessor accessor;
+        hashPath(
+            accessor, CanonPath { path },
+            FileIngestionMethod::Recursive, HashAlgorithm::SHA256).first;
+    });
     debug("'%1%' has hash '%2%'", path, hash.to_string(HashFormat::Nix32, true));
 
     /* Check if this is a known hash. */
@@ -156,7 +162,12 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
     if (pathExists(linkPath)) {
         auto stLink = lstat(linkPath);
         if (st.st_size != stLink.st_size
-            || (repair && hash != hashPath(HashAlgorithm::SHA256, linkPath).first))
+            || (repair && hash != ({
+                PosixSourceAccessor accessor;
+                hashPath(
+                    accessor, CanonPath { linkPath },
+                    FileIngestionMethod::Recursive, HashAlgorithm::SHA256).first;
+           })))
         {
             // XXX: Consider overwriting linkPath with our valid version.
             warn("removing corrupted link '%s'", linkPath);

src/libstore/remote-store.cc

@@ -502,8 +502,13 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
 }
 
 
-StorePath RemoteStore::addToStoreFromDump(Source & dump, std::string_view name,
+StorePath RemoteStore::addToStoreFromDump(
-                                          FileIngestionMethod method, HashAlgorithm hashAlgo, RepairFlag repair, const StorePathSet & references)
+    Source & dump,
+    std::string_view name,
+    ContentAddressMethod method,
+    HashAlgorithm hashAlgo,
+    const StorePathSet & references,
+    RepairFlag repair)
 {
     return addCAToStore(dump, name, method, hashAlgo, references, repair)->path;
 }

src/libstore/remote-store.hh

@@ -82,10 +82,15 @@ public:
             RepairFlag repair);
 
     /**
-     * Add a content-addressable store path. Does not support references. `dump` will be drained.
+     * Add a content-addressable store path. `dump` will be drained.
      */
-    StorePath addToStoreFromDump(Source & dump, std::string_view name,
+    StorePath addToStoreFromDump(
-                                 FileIngestionMethod method = FileIngestionMethod::Recursive, HashAlgorithm hashAlgo = HashAlgorithm::SHA256, RepairFlag repair = NoRepair, const StorePathSet & references = StorePathSet()) override;
+        Source & dump,
+        std::string_view name,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
+        HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
+        const StorePathSet & references = StorePathSet(),
+        RepairFlag repair = NoRepair) override;
 
     void addToStore(const ValidPathInfo & info, Source & nar,
         RepairFlag repair, CheckSigsFlag checkSigs) override;

src/libstore/store-api.cc

@@ -232,22 +232,28 @@ StorePath StoreDirConfig::makeFixedOutputPathFromCA(std::string_view name, const
 }
 
 
-std::pair<StorePath, Hash> StoreDirConfig::computeStorePathFromDump(
+std::pair<StorePath, Hash> StoreDirConfig::computeStorePath(
-        Source & dump,
     std::string_view name,
-        FileIngestionMethod method,
+    SourceAccessor & accessor,
+    const CanonPath & path,
+    ContentAddressMethod method,
     HashAlgorithm hashAlgo,
-        const StorePathSet & references) const
+    const StorePathSet & references,
+    PathFilter & filter) const
 {
-    HashSink sink(hashAlgo);
+    auto h = hashPath(accessor, path, method.getFileIngestionMethod(), hashAlgo, filter).first;
-    dump.drainInto(sink);
+    return {
-    auto h = sink.finish().first;
+        makeFixedOutputPathFromCA(
-    FixedOutputInfo caInfo {
+            name,
-        .method = method,
+            ContentAddressWithReferences::fromParts(
-        .hash = h,
+                method,
-        .references = {},
+                h,
+                {
+                    .others = references,
+                    .self = false,
+                })),
+        h,
     };
-    return std::make_pair(makeFixedOutputPath(name, caInfo), h);
 }
 
 
@@ -265,21 +271,18 @@ StorePath StoreDirConfig::computeStorePathForText(
 
 StorePath Store::addToStore(
     std::string_view name,
-        const Path & _srcPath,
+    SourceAccessor & accessor,
-        FileIngestionMethod method,
+    const CanonPath & path,
+    ContentAddressMethod method,
     HashAlgorithm hashAlgo,
+    const StorePathSet & references,
     PathFilter & filter,
-        RepairFlag repair,
+    RepairFlag repair)
-        const StorePathSet & references)
 {
-    Path srcPath(absPath(_srcPath));
     auto source = sinkToSource([&](Sink & sink) {
-        if (method == FileIngestionMethod::Recursive)
+        dumpPath(accessor, path, sink, method.getFileIngestionMethod(), filter);
-            dumpPath(srcPath, sink, filter);
-        else
-            readFile(srcPath, sink);
     });
-    return addToStoreFromDump(*source, name, method, hashAlgo, repair, references);
+    return addToStoreFromDump(*source, name, method, hashAlgo, references, repair);
 }
 
 void Store::addMultipleToStore(
@@ -404,8 +407,12 @@ digraph graphname {
     fileSink -> caHashSink
 }
 */
-ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
+ValidPathInfo Store::addToStoreSlow(
-                                    FileIngestionMethod method, HashAlgorithm hashAlgo,
+    std::string_view name,
+    SourceAccessor & accessor,
+    const CanonPath & srcPath,
+    ContentAddressMethod method, HashAlgorithm hashAlgo,
+    const StorePathSet & references,
     std::optional<Hash> expectedCAHash)
 {
     HashSink narHashSink { HashAlgorithm::SHA256 };
@@ -425,7 +432,7 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
        srcPath. The fact that we use scratchpadSink as a temporary buffer here
        is an implementation detail. */
     auto fileSource = sinkToSource([&](Sink & scratchpadSink) {
-        dumpPath(srcPath, scratchpadSink);
+        accessor.dumpPath(srcPath, scratchpadSink);
     });
 
     /* tapped provides the same data as fileSource, but we also write all the
@@ -433,9 +440,11 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
     TeeSource tapped { *fileSource, narSink };
 
     NullParseSink blank;
-    auto & parseSink = method == FileIngestionMethod::Flat
+    auto & parseSink = method.getFileIngestionMethod() == FileIngestionMethod::Flat
         ? (ParseSink &) fileSink
-        : (ParseSink &) blank;
+        : method.getFileIngestionMethod() == FileIngestionMethod::Recursive
+        ? (ParseSink &) blank
+        : (abort(), (ParseSink &)*(ParseSink *)nullptr); // handled both cases
 
     /* The information that flows from tapped (besides being replicated in
        narSink), is now put in parseSink. */
@@ -452,21 +461,24 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
     if (expectedCAHash && expectedCAHash != hash)
         throw Error("hash mismatch for '%s'", srcPath);
 
+
     ValidPathInfo info {
         *this,
         name,
-        FixedOutputInfo {
+        ContentAddressWithReferences::fromParts(
-            .method = method,
+            method,
-            .hash = hash,
+            hash,
-            .references = {},
+            {
-        },
+                .others = references,
+                .self = false,
+            }),
         narHash,
     };
     info.narSize = narSize;
 
     if (!isValidPath(info.path)) {
         auto source = sinkToSource([&](Sink & scratchpadSink) {
-            dumpPath(srcPath, scratchpadSink);
+            accessor.dumpPath(srcPath, scratchpadSink);
         });
         addToStore(info, *source);
     }

src/libstore/store-api.hh

@@ -428,20 +428,26 @@ public:
      */
     virtual StorePath addToStore(
         std::string_view name,
-            const Path & srcPath,
+        SourceAccessor & accessor,
-            FileIngestionMethod method = FileIngestionMethod::Recursive,
+        const CanonPath & path,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
         HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
+        const StorePathSet & references = StorePathSet(),
         PathFilter & filter = defaultPathFilter,
-            RepairFlag repair = NoRepair,
+        RepairFlag repair = NoRepair);
-            const StorePathSet & references = StorePathSet());
 
     /**
      * Copy the contents of a path to the store and register the
      * validity the resulting path, using a constant amount of
      * memory.
      */
-    ValidPathInfo addToStoreSlow(std::string_view name, const Path & srcPath,
+    ValidPathInfo addToStoreSlow(
-                                 FileIngestionMethod method = FileIngestionMethod::Recursive, HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
+        std::string_view name,
+        SourceAccessor & accessor,
+        const CanonPath & path,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
+        HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
+        const StorePathSet & references = StorePathSet(),
         std::optional<Hash> expectedCAHash = {});
 
     /**
@@ -453,9 +459,13 @@ public:
      *
      * \todo remove?
      */
-    virtual StorePath addToStoreFromDump(Source & dump, std::string_view name,
+    virtual StorePath addToStoreFromDump(
-                                         FileIngestionMethod method = FileIngestionMethod::Recursive, HashAlgorithm hashAlgo = HashAlgorithm::SHA256, RepairFlag repair = NoRepair,
+        Source & dump,
-                                         const StorePathSet & references = StorePathSet())
+        std::string_view name,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
+        HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
+        const StorePathSet & references = StorePathSet(),
+        RepairFlag repair = NoRepair)
     { unsupported("addToStoreFromDump"); }
 
     /**

src/libstore/store-dir-config.hh

@@ -91,15 +91,17 @@ struct StoreDirConfig : public Config
     StorePath makeFixedOutputPathFromCA(std::string_view name, const ContentAddressWithReferences & ca) const;
 
     /**
-     * Read-only variant of addToStoreFromDump(). It returns the store
+     * Read-only variant of addToStore(). It returns the store
-     * path to which a NAR or flat file would be written.
+     * path for the given file sytem object.
      */
-    std::pair<StorePath, Hash> computeStorePathFromDump(
+    std::pair<StorePath, Hash> computeStorePath(
-        Source & dump,
         std::string_view name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive,
+        SourceAccessor & accessor,
+        const CanonPath & path,
+        ContentAddressMethod method = FileIngestionMethod::Recursive,
         HashAlgorithm hashAlgo = HashAlgorithm::SHA256,
-        const StorePathSet & references = {}) const;
+        const StorePathSet & references = {},
+        PathFilter & filter = defaultPathFilter) const;
 
     /**
      * Preparatory part of addTextToStore().

src/libutil/file-content-address.cc

@@ -0,0 +1,49 @@
+#include "file-content-address.hh"
+#include "archive.hh"
+
+namespace nix {
+
+void dumpPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    Sink & sink,
+    FileIngestionMethod method,
+    PathFilter & filter)
+{
+    switch (method) {
+    case FileIngestionMethod::Flat:
+        accessor.readFile(path, sink);
+        break;
+    case FileIngestionMethod::Recursive:
+        accessor.dumpPath(path, sink, filter);
+        break;
+    }
+}
+
+
+void restorePath(
+    const Path & path,
+    Source & source,
+    FileIngestionMethod method)
+{
+    switch (method) {
+    case FileIngestionMethod::Flat:
+        writeFile(path, source);
+        break;
+    case FileIngestionMethod::Recursive:
+        restorePath(path, source);
+        break;
+    }
+}
+
+
+HashResult hashPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    FileIngestionMethod method, HashAlgorithm ht,
+    PathFilter & filter)
+{
+    HashSink sink { ht };
+    dumpPath(accessor, path, sink, method, filter);
+    return sink.finish();
+}
+
+}

src/libutil/file-content-address.hh

@@ -0,0 +1,56 @@
+#pragma once
+///@file
+
+#include "source-accessor.hh"
+#include "fs-sink.hh"
+#include "util.hh"
+
+namespace nix {
+
+/**
+ * An enumeration of the main ways we can serialize file system
+ * objects.
+ */
+enum struct FileIngestionMethod : uint8_t {
+    /**
+     * Flat-file hashing. Directly ingest the contents of a single file
+     */
+    Flat = 0,
+    /**
+     * Recursive (or NAR) hashing. Serializes the file-system object in
+     * Nix Archive format and ingest that.
+     */
+    Recursive = 1,
+};
+
+/**
+ * Dump a serialization of the given file system object.
+ */
+void dumpPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    Sink & sink,
+    FileIngestionMethod method,
+    PathFilter & filter = defaultPathFilter);
+
+/**
+ * Restore a serialization of the given file system object.
+ *
+ * @TODO use an arbitrary `ParseSink`.
+ */
+void restorePath(
+    const Path & path,
+    Source & source,
+    FileIngestionMethod method);
+
+/**
+ * Compute the hash of the given file system object according to the
+ * given method.
+ *
+ * The hash is defined as (essentially) hashString(ht, dumpPath(path)).
+ */
+HashResult hashPath(
+    SourceAccessor & accessor, const CanonPath & path,
+    FileIngestionMethod method, HashAlgorithm ht,
+    PathFilter & filter = defaultPathFilter);
+
+}

src/libutil/hash.cc

@@ -367,15 +367,6 @@ HashResult HashSink::currentHash()
 }
 
 
-HashResult hashPath(
-        HashAlgorithm ha, const Path & path, PathFilter & filter)
-{
-    HashSink sink(ha);
-    dumpPath(path, sink, filter);
-    return sink.finish();
-}
-
-
 Hash compressHash(const Hash & hash, unsigned int newSize)
 {
     Hash h(hash.algo);

src/libutil/hash.hh

@@ -168,14 +168,11 @@ Hash hashString(HashAlgorithm ha, std::string_view s);
 Hash hashFile(HashAlgorithm ha, const Path & path);
 
 /**
- * Compute the hash of the given path, serializing as a Nix Archive and
+ * The final hash and the number of bytes digested.
- * then hashing that.
  *
- * The hash is defined as (essentially) hashString(ht, dumpPath(path)).
+ * @todo Convert to proper struct
  */
 typedef std::pair<Hash, uint64_t> HashResult;
-HashResult hashPath(HashAlgorithm ha, const Path & path,
-                    PathFilter & filter = defaultPathFilter);
 
 /**
  * Compress a hash to the specified number of bytes by cyclically

src/nix-store/nix-store.cc

@@ -13,6 +13,7 @@
 #include "shared.hh"
 #include "graphml.hh"
 #include "legacy.hh"
+#include "posix-source-accessor.hh"
 #include "path-with-outputs.hh"
 #include "posix-fs-canonicalise.hh"
 
@@ -175,8 +176,12 @@ static void opAdd(Strings opFlags, Strings opArgs)
 {
     if (!opFlags.empty()) throw UsageError("unknown flag");
 
+    PosixSourceAccessor accessor;
     for (auto & i : opArgs)
-        cout << fmt("%s\n", store->printStorePath(store->addToStore(std::string(baseNameOf(i)), i)));
+        cout << fmt("%s\n", store->printStorePath(store->addToStore(
+            std::string(baseNameOf(i)),
+            accessor,
+            CanonPath::fromCwd(i))));
 }
 
 
@@ -196,8 +201,14 @@ static void opAddFixed(Strings opFlags, Strings opArgs)
     HashAlgorithm hashAlgo = parseHashAlgo(opArgs.front());
     opArgs.pop_front();
 
+    PosixSourceAccessor accessor;
     for (auto & i : opArgs)
-        std::cout << fmt("%s\n", store->printStorePath(store->addToStoreSlow(baseNameOf(i), i, method, hashAlgo).path));
+        std::cout << fmt("%s\n", store->printStorePath(store->addToStoreSlow(
+            baseNameOf(i),
+            accessor,
+            CanonPath::fromCwd(i),
+            method,
+            hashAlgo).path));
 }
 
 
@@ -541,7 +552,10 @@ static void registerValidity(bool reregister, bool hashGiven, bool canonicalise)
             if (canonicalise)
                 canonicalisePathMetaData(store->printStorePath(info->path), {});
             if (!hashGiven) {
-                HashResult hash = hashPath(HashAlgorithm::SHA256, store->printStorePath(info->path));
+                HashResult hash = hashPath(
+                    *store->getFSAccessor(false), CanonPath { store->printStorePath(info->path) },
+
+                    FileIngestionMethod::Recursive, HashAlgorithm::SHA256);
                 info->narHash = hash.first;
                 info->narSize = hash.second;
             }

src/nix/add-to-store.cc

@@ -2,6 +2,7 @@
 #include "common-args.hh"
 #include "store-api.hh"
 #include "archive.hh"
+#include "posix-source-accessor.hh"
 
 using namespace nix;
 
@@ -20,7 +21,7 @@ struct CmdAddToStore : MixDryRun, StoreCommand
 {
     Path path;
     std::optional<std::string> namePart;
-    FileIngestionMethod ingestionMethod = FileIngestionMethod::Recursive;
+    ContentAddressMethod caMethod = FileIngestionMethod::Recursive;
 
     CmdAddToStore()
     {
@@ -48,7 +49,7 @@ struct CmdAddToStore : MixDryRun, StoreCommand
             )",
             .labels = {"hash-mode"},
             .handler = {[this](std::string s) {
-                this->ingestionMethod = parseIngestionMethod(s);
+                this->caMethod = parseIngestionMethod(s);
             }},
         });
     }
@@ -57,36 +58,17 @@ struct CmdAddToStore : MixDryRun, StoreCommand
     {
         if (!namePart) namePart = baseNameOf(path);
 
-        StringSink sink;
+        PosixSourceAccessor accessor;
-        dumpPath(path, sink);
 
-        auto narHash = hashString(HashAlgorithm::SHA256, sink.s);
+        auto path2 = CanonPath::fromCwd(path);
 
-        Hash hash = narHash;
+        auto storePath = dryRun
-        if (ingestionMethod == FileIngestionMethod::Flat) {
+            ? store->computeStorePath(
-            HashSink hsink(HashAlgorithm::SHA256);
+                *namePart, accessor, path2, caMethod, HashAlgorithm::SHA256, {}).first
-            readFile(path, hsink);
+            : store->addToStoreSlow(
-            hash = hsink.finish().first;
+                *namePart, accessor, path2, caMethod, HashAlgorithm::SHA256, {}).path;
-        }
 
-        ValidPathInfo info {
+        logger->cout("%s", store->printStorePath(storePath));
-            *store,
-            std::move(*namePart),
-            FixedOutputInfo {
-                .method = std::move(ingestionMethod),
-                .hash = std::move(hash),
-                .references = {},
-            },
-            narHash,
-        };
-        info.narSize = sink.s.size();
-
-        if (!dryRun) {
-            auto source = StringSource(sink.s);
-            store->addToStore(info, source);
-        }
-
-        logger->cout("%s", store->printStorePath(info.path));
     }
 };
 
@@ -110,7 +92,7 @@ struct CmdAddFile : CmdAddToStore
 {
     CmdAddFile()
     {
-        ingestionMethod = FileIngestionMethod::Flat;
+        caMethod = FileIngestionMethod::Flat;
     }
 
     std::string description() override

src/nix/hash.cc

@@ -5,6 +5,7 @@
 #include "shared.hh"
 #include "references.hh"
 #include "archive.hh"
+#include "posix-source-accessor.hh"
 
 using namespace nix;
 
@@ -88,14 +89,8 @@ struct CmdHashBase : Command
             else
                 hashSink = std::make_unique<HashSink>(ha);
 
-            switch (mode) {
+            PosixSourceAccessor accessor;
-            case FileIngestionMethod::Flat:
+            dumpPath(accessor, CanonPath::fromCwd(path), *hashSink, mode);
-                readFile(path, *hashSink);
-                break;
-            case FileIngestionMethod::Recursive:
-                dumpPath(path, *hashSink);
-                break;
-            }
 
             Hash h = hashSink->finish().first;
             if (truncate && h.hashSize > 20) h = compressHash(h, 20);

src/nix/prefetch.cc

@@ -9,6 +9,7 @@
 #include "attr-path.hh"
 #include "eval-inline.hh"
 #include "legacy.hh"
+#include "posix-source-accessor.hh"
 
 #include <nlohmann/json.hpp>
 
@@ -122,7 +123,11 @@ std::tuple<StorePath, Hash> prefetchFile(
         Activity act(*logger, lvlChatty, actUnknown,
             fmt("adding '%s' to the store", url));
 
-        auto info = store->addToStoreSlow(*name, tmpFile, ingestionMethod, hashAlgo, expectedHash);
+        PosixSourceAccessor accessor;
+        auto info = store->addToStoreSlow(
+            *name,
+            accessor, CanonPath::fromCwd(tmpFile),
+            ingestionMethod, hashAlgo, {}, expectedHash);
         storePath = info.path;
         assert(info.ca);
         hash = info.ca->hash;

tests/unit/libexpr/primops.cc

@@ -604,7 +604,7 @@ namespace nix {
         ASSERT_THAT(v, IsStringEq("401b09eab3c013d4ca54922bb802bec8fd5318192b0a75f201d8b3727429080fb337591abd3e44453b954555b7a0812e1081c39b740293f765eae731f5a65ed1"));
     }
 
-    TEST_F(PrimOpTest, hashStringInvalidHashType) {
+    TEST_F(PrimOpTest, hashStringInvalidHashAlgorithm) {
         ASSERT_THROW(eval("builtins.hashString \"foobar\" \"asdf\""), Error);
     }