Make the Store API more type-safe

Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).

1 files changed, 82 insertions, 67 deletions

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index d3c17e772..c53dfdd56 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -260,14 +260,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     switch (op) {
 
     case wopIsValidPath: {
-        /* 'readStorePath' could raise an error leading to the connection
-           being closed.  To be able to recover from an invalid path error,
-           call 'startWork' early, and do 'assertStorePath' afterwards so
-           that the 'Error' exception handler doesn't close the
-           connection.  */
-        Path path = readString(from);
-        logger->startWork();
-        store->assertStorePath(path);
+        auto path = store->parseStorePath(readString(from));
+        logger->startWork();
         bool result = store->isValidPath(path);
         logger->stopWork();
         to << result;
@@ -275,34 +269,36 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQueryValidPaths: {
-        PathSet paths = readStorePaths<PathSet>(*store, from);
+        auto paths = readStorePaths<StorePathSet>(*store, from);
         logger->startWork();
-        PathSet res = store->queryValidPaths(paths);
+        auto res = store->queryValidPaths(paths);
         logger->stopWork();
-        to << res;
+        writeStorePaths(*store, to, res);
         break;
     }
 
     case wopHasSubstitutes: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
-        PathSet res = store->querySubstitutablePaths({path});
+        StorePathSet paths; // FIXME
+        paths.insert(path.clone());
+        auto res = store->querySubstitutablePaths(paths);
         logger->stopWork();
-        to << (res.find(path) != res.end());
+        to << (res.count(path) != 0);
         break;
     }
 
     case wopQuerySubstitutablePaths: {
-        PathSet paths = readStorePaths<PathSet>(*store, from);
+        auto paths = readStorePaths<StorePathSet>(*store, from);
         logger->startWork();
-        PathSet res = store->querySubstitutablePaths(paths);
+        auto res = store->querySubstitutablePaths(paths);
         logger->stopWork();
-        to << res;
+        writeStorePaths(*store, to, res);
         break;
     }
 
     case wopQueryPathHash: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         auto hash = store->queryPathInfo(path)->narHash;
         logger->stopWork();
@@ -314,23 +310,24 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopQueryReferrers:
     case wopQueryValidDerivers:
     case wopQueryDerivationOutputs: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
-        PathSet paths;
+        StorePathSet paths;
         if (op == wopQueryReferences)
-            paths = store->queryPathInfo(path)->references;
+            for (auto & i : store->queryPathInfo(path)->references)
+                paths.insert(i.clone());
         else if (op == wopQueryReferrers)
             store->queryReferrers(path, paths);
         else if (op == wopQueryValidDerivers)
             paths = store->queryValidDerivers(path);
         else paths = store->queryDerivationOutputs(path);
         logger->stopWork();
-        to << paths;
+        writeStorePaths(*store, to, paths);
         break;
     }
 
     case wopQueryDerivationOutputNames: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         StringSet names;
         names = store->queryDerivationOutputNames(path);
@@ -340,20 +337,20 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQueryDeriver: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
-        auto deriver = store->queryPathInfo(path)->deriver;
+        auto info = store->queryPathInfo(path);
         logger->stopWork();
-        to << deriver;
+        to << (info->deriver ? store->printStorePath(*info->deriver) : "");
         break;
     }
 
     case wopQueryPathFromHashPart: {
-        string hashPart = readString(from);
+        auto hashPart = readString(from);
         logger->startWork();
-        Path path = store->queryPathFromHashPart(hashPart);
+        auto path = store->queryPathFromHashPart(hashPart);
         logger->stopWork();
-        to << path;
+        to << (path ? store->printStorePath(*path) : "");
         break;
     }
 
@@ -383,26 +380,26 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         if (!savedRegular.regular) throw Error("regular file expected");
 
-        Path path = store->addToStoreFromDump(recursive ? *savedNAR.data : savedRegular.s, baseName, recursive, hashAlgo);
+        auto path = store->addToStoreFromDump(recursive ? *savedNAR.data : savedRegular.s, baseName, recursive, hashAlgo);
         logger->stopWork();
 
-        to << path;
+        to << store->printStorePath(path);
         break;
     }
 
     case wopAddTextToStore: {
         string suffix = readString(from);
         string s = readString(from);
-        PathSet refs = readStorePaths<PathSet>(*store, from);
+        auto refs = readStorePaths<StorePathSet>(*store, from);
         logger->startWork();
-        Path path = store->addTextToStore(suffix, s, refs, NoRepair);
+        auto path = store->addTextToStore(suffix, s, refs, NoRepair);
         logger->stopWork();
-        to << path;
+        to << store->printStorePath(path);
         break;
     }
 
     case wopExportPath: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         readInt(from); // obsolete
         logger->startWork();
         TunnelSink sink(to);
@@ -415,15 +412,19 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopImportPaths: {
         logger->startWork();
         TunnelSource source(from, to);
-        Paths paths = store->importPaths(source, nullptr,
+        auto paths = store->importPaths(source, nullptr,
             trusted ? NoCheckSigs : CheckSigs);
         logger->stopWork();
-        to << paths;
+        Strings paths2;
+        for (auto & i : paths) paths2.push_back(store->printStorePath(i));
+        to << paths2;
         break;
     }
 
     case wopBuildPaths: {
-        PathSet drvs = readStorePaths<PathSet>(*store, from);
+        std::vector<StorePathWithOutputs> drvs;
+        for (auto & s : readStrings<Strings>(from))
+            drvs.push_back(store->parseDrvPathWithOutputs(s));
         BuildMode mode = bmNormal;
         if (GET_PROTOCOL_MINOR(clientVersion) >= 15) {
             mode = (BuildMode) readInt(from);
@@ -441,7 +442,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopBuildDerivation: {
-        Path drvPath = readStorePath(*store, from);
+        auto drvPath = store->parseStorePath(readString(from));
         BasicDerivation drv;
         readDerivation(from, *store, drv);
         BuildMode buildMode = (BuildMode) readInt(from);
@@ -455,7 +456,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopEnsurePath: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         store->ensurePath(path);
         logger->stopWork();
@@ -464,7 +465,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddTempRoot: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         store->addTempRoot(path);
         logger->stopWork();
@@ -502,7 +503,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
 
         for (auto & [target, links] : roots)
             for (auto & link : links)
-                to << link << target;
+                to << link << store->printStorePath(target);
 
         break;
     }
@@ -510,7 +511,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopCollectGarbage: {
         GCOptions options;
         options.action = (GCOptions::GCAction) readInt(from);
-        options.pathsToDelete = readStorePaths<PathSet>(*store, from);
+        options.pathsToDelete = readStorePaths<StorePathSet>(*store, from);
         from >> options.ignoreLiveness >> options.maxFreed;
         // obsolete fields
         readInt(from);
@@ -568,44 +569,52 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQuerySubstitutablePathInfo: {
-        Path path = absPath(readString(from));
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         SubstitutablePathInfos infos;
-        store->querySubstitutablePathInfos({path}, infos);
+        StorePathSet paths;
+        paths.insert(path.clone()); // FIXME
+        store->querySubstitutablePathInfos(paths, infos);
         logger->stopWork();
-        SubstitutablePathInfos::iterator i = infos.find(path);
+        auto i = infos.find(path);
         if (i == infos.end())
             to << 0;
         else {
-            to << 1 << i->second.deriver << i->second.references << i->second.downloadSize << i->second.narSize;
+            to << 1
+               << (i->second.deriver ? store->printStorePath(*i->second.deriver) : "");
+            writeStorePaths(*store, to, i->second.references);
+            to << i->second.downloadSize
+               << i->second.narSize;
         }
         break;
     }
 
     case wopQuerySubstitutablePathInfos: {
-        PathSet paths = readStorePaths<PathSet>(*store, from);
+        auto paths = readStorePaths<StorePathSet>(*store, from);
         logger->startWork();
         SubstitutablePathInfos infos;
         store->querySubstitutablePathInfos(paths, infos);
         logger->stopWork();
         to << infos.size();
         for (auto & i : infos) {
-            to << i.first << i.second.deriver << i.second.references
-               << i.second.downloadSize << i.second.narSize;
+            to << store->printStorePath(i.first)
+               << (i.second.deriver ? store->printStorePath(*i.second.deriver) : "");
+            writeStorePaths(*store, to, i.second.references);
+            to << i.second.downloadSize << i.second.narSize;
         }
         break;
     }
 
     case wopQueryAllValidPaths: {
         logger->startWork();
-        PathSet paths = store->queryAllValidPaths();
+        auto paths = store->queryAllValidPaths();
         logger->stopWork();
-        to << paths;
+        writeStorePaths(*store, to, paths);
         break;
     }
 
     case wopQueryPathInfo: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         std::shared_ptr<const ValidPathInfo> info;
         logger->startWork();
         try {
@@ -617,8 +626,10 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         if (info) {
             if (GET_PROTOCOL_MINOR(clientVersion) >= 17)
                 to << 1;
-            to << info->deriver << info->narHash.to_string(Base16, false) << info->references
-               << info->registrationTime << info->narSize;
+            to << (info->deriver ? store->printStorePath(*info->deriver) : "")
+               << info->narHash.to_string(Base16, false);
+            writeStorePaths(*store, to, info->references);
+            to << info->registrationTime << info->narSize;
             if (GET_PROTOCOL_MINOR(clientVersion) >= 16) {
                 to << info->ultimate
                    << info->sigs
@@ -651,7 +662,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddSignatures: {
-        Path path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         StringSet sigs = readStrings<StringSet>(from);
         logger->startWork();
         if (!trusted)
@@ -663,22 +674,21 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopNarFromPath: {
-        auto path = readStorePath(*store, from);
+        auto path = store->parseStorePath(readString(from));
         logger->startWork();
         logger->stopWork();
-        dumpPath(path, to);
+        dumpPath(store->printStorePath(path), to);
         break;
     }
 
     case wopAddToStoreNar: {
         bool repair, dontCheckSigs;
-        ValidPathInfo info;
-        info.path = readStorePath(*store, from);
-        from >> info.deriver;
-        if (!info.deriver.empty())
-            store->assertStorePath(info.deriver);
+        ValidPathInfo info(store->parseStorePath(readString(from)));
+        auto deriver = readString(from);
+        if (deriver != "")
+            info.deriver = store->parseStorePath(deriver);
         info.narHash = Hash(readString(from), htSHA256);
-        info.references = readStorePaths<PathSet>(*store, from);
+        info.references = readStorePaths<StorePathSet>(*store, from);
         from >> info.registrationTime >> info.narSize >> info.ultimate;
         info.sigs = readStrings<StringSet>(from);
         from >> info.ca >> repair >> dontCheckSigs;
@@ -709,13 +719,18 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQueryMissing: {
-        PathSet targets = readStorePaths<PathSet>(*store, from);
+        std::vector<StorePathWithOutputs> targets;
+        for (auto & s : readStrings<Strings>(from))
+            targets.push_back(store->parseDrvPathWithOutputs(s));
         logger->startWork();
-        PathSet willBuild, willSubstitute, unknown;
+        StorePathSet willBuild, willSubstitute, unknown;
         unsigned long long downloadSize, narSize;
         store->queryMissing(targets, willBuild, willSubstitute, unknown, downloadSize, narSize);
         logger->stopWork();
-        to << willBuild << willSubstitute << unknown << downloadSize << narSize;
+        writeStorePaths(*store, to, willBuild);
+        writeStorePaths(*store, to, willSubstitute);
+        writeStorePaths(*store, to, unknown);
+        to << downloadSize << narSize;
         break;
     }