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, 12 insertions, 12 deletions

diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 2d7cd1947..fa2200ad8 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -65,18 +65,18 @@ private:
 
     std::string narMagic;
 
-    std::string narInfoFileFor(const Path & storePath);
+    std::string narInfoFileFor(const StorePath & storePath);
 
     void writeNarInfo(ref<NarInfo> narInfo);
 
 public:
 
-    bool isValidPathUncached(const Path & path) override;
+    bool isValidPathUncached(const StorePath & path) override;
 
-    void queryPathInfoUncached(const Path & path,
+    void queryPathInfoUncached(const StorePath & path,
         Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept override;
 
-    Path queryPathFromHashPart(const string & hashPart) override
+    std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { unsupported("queryPathFromHashPart"); }
 
     bool wantMassQuery() override { return wantMassQuery_; }
@@ -85,27 +85,27 @@ public:
         RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override;
 
-    Path addToStore(const string & name, const Path & srcPath,
+    StorePath addToStore(const string & name, const Path & srcPath,
         bool recursive, HashType hashAlgo,
         PathFilter & filter, RepairFlag repair) override;
 
-    Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, RepairFlag repair) override;
+    StorePath addTextToStore(const string & name, const string & s,
+        const StorePathSet & references, RepairFlag repair) override;
 
-    void narFromPath(const Path & path, Sink & sink) override;
+    void narFromPath(const StorePath & path, Sink & sink) override;
 
-    BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
+    BuildResult buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
         BuildMode buildMode) override
     { unsupported("buildDerivation"); }
 
-    void ensurePath(const Path & path) override
+    void ensurePath(const StorePath & path) override
     { unsupported("ensurePath"); }
 
     ref<FSAccessor> getFSAccessor() override;
 
-    void addSignatures(const Path & storePath, const StringSet & sigs) override;
+    void addSignatures(const StorePath & storePath, const StringSet & sigs) override;
 
-    std::shared_ptr<std::string> getBuildLog(const Path & path) override;
+    std::shared_ptr<std::string> getBuildLog(const StorePath & path) override;
 
     int getPriority() override { return priority; }