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, 42 insertions, 43 deletions

diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index ce553bb53..fefcd5ae6 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -59,7 +59,7 @@ void setVerbosity(int level)
 int isValidPath(char * path)
     CODE:
         try {
-            RETVAL = store()->isValidPath(path);
+            RETVAL = store()->isValidPath(store()->parseStorePath(path));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -70,9 +70,8 @@ int isValidPath(char * path)
 SV * queryReferences(char * path)
     PPCODE:
         try {
-            PathSet paths = store()->queryPathInfo(path)->references;
-            for (PathSet::iterator i = paths.begin(); i != paths.end(); ++i)
-                XPUSHs(sv_2mortal(newSVpv(i->c_str(), 0)));
+            for (auto & i : store()->queryPathInfo(store()->parseStorePath(path))->references)
+                XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(i).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -81,7 +80,7 @@ SV * queryReferences(char * path)
 SV * queryPathHash(char * path)
     PPCODE:
         try {
-            auto s = store()->queryPathInfo(path)->narHash.to_string();
+            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string();
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -91,9 +90,9 @@ SV * queryPathHash(char * path)
 SV * queryDeriver(char * path)
     PPCODE:
         try {
-            auto deriver = store()->queryPathInfo(path)->deriver;
-            if (deriver == "") XSRETURN_UNDEF;
-            XPUSHs(sv_2mortal(newSVpv(deriver.c_str(), 0)));
+            auto info = store()->queryPathInfo(store()->parseStorePath(path));
+            if (!info->deriver) XSRETURN_UNDEF;
+            XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(*info->deriver).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -102,18 +101,18 @@ SV * queryDeriver(char * path)
 SV * queryPathInfo(char * path, int base32)
     PPCODE:
         try {
-            auto info = store()->queryPathInfo(path);
-            if (info->deriver == "")
+            auto info = store()->queryPathInfo(store()->parseStorePath(path));
+            if (info->deriver)
                 XPUSHs(&PL_sv_undef);
             else
-                XPUSHs(sv_2mortal(newSVpv(info->deriver.c_str(), 0)));
+                XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(*info->deriver).c_str(), 0)));
             auto s = info->narHash.to_string(base32 ? Base32 : Base16);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
             mXPUSHi(info->registrationTime);
             mXPUSHi(info->narSize);
             AV * arr = newAV();
-            for (PathSet::iterator i = info->references.begin(); i != info->references.end(); ++i)
-                av_push(arr, newSVpv(i->c_str(), 0));
+            for (auto & i : info->references)
+                av_push(arr, newSVpv(store()->printStorePath(i).c_str(), 0));
             XPUSHs(sv_2mortal(newRV((SV *) arr)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -123,8 +122,8 @@ SV * queryPathInfo(char * path, int base32)
 SV * queryPathFromHashPart(char * hashPart)
     PPCODE:
         try {
-            Path path = store()->queryPathFromHashPart(hashPart);
-            XPUSHs(sv_2mortal(newSVpv(path.c_str(), 0)));
+            auto path = store()->queryPathFromHashPart(hashPart);
+            XPUSHs(sv_2mortal(newSVpv(path ? store()->printStorePath(*path).c_str() : "", 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -133,11 +132,11 @@ SV * queryPathFromHashPart(char * hashPart)
 SV * computeFSClosure(int flipDirection, int includeOutputs, ...)
     PPCODE:
         try {
-            PathSet paths;
+            StorePathSet paths;
             for (int n = 2; n < items; ++n)
-                store()->computeFSClosure(SvPV_nolen(ST(n)), paths, flipDirection, includeOutputs);
-            for (PathSet::iterator i = paths.begin(); i != paths.end(); ++i)
-                XPUSHs(sv_2mortal(newSVpv(i->c_str(), 0)));
+                store()->computeFSClosure(store()->parseStorePath(SvPV_nolen(ST(n))), paths, flipDirection, includeOutputs);
+            for (auto & i : paths)
+                XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(i).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -146,11 +145,11 @@ SV * computeFSClosure(int flipDirection, int includeOutputs, ...)
 SV * topoSortPaths(...)
     PPCODE:
         try {
-            PathSet paths;
-            for (int n = 0; n < items; ++n) paths.insert(SvPV_nolen(ST(n)));
-            Paths sorted = store()->topoSortPaths(paths);
-            for (Paths::iterator i = sorted.begin(); i != sorted.end(); ++i)
-                XPUSHs(sv_2mortal(newSVpv(i->c_str(), 0)));
+            StorePathSet paths;
+            for (int n = 0; n < items; ++n) paths.insert(store()->parseStorePath(SvPV_nolen(ST(n))));
+            auto sorted = store()->topoSortPaths(paths);
+            for (auto & i : sorted)
+                XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(i).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -159,7 +158,7 @@ SV * topoSortPaths(...)
 SV * followLinksToStorePath(char * path)
     CODE:
         try {
-            RETVAL = newSVpv(store()->followLinksToStorePath(path).c_str(), 0);
+            RETVAL = newSVpv(store()->printStorePath(store()->followLinksToStorePath(path)).c_str(), 0);
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -170,8 +169,8 @@ SV * followLinksToStorePath(char * path)
 void exportPaths(int fd, ...)
     PPCODE:
         try {
-            Paths paths;
-            for (int n = 1; n < items; ++n) paths.push_back(SvPV_nolen(ST(n)));
+            StorePathSet paths;
+            for (int n = 1; n < items; ++n) paths.insert(store()->parseStorePath(SvPV_nolen(ST(n))));
             FdSink sink(fd);
             store()->exportPaths(paths, sink);
         } catch (Error & e) {
@@ -275,8 +274,8 @@ int checkSignature(SV * publicKey_, SV * sig_, char * msg)
 SV * addToStore(char * srcPath, int recursive, char * algo)
     PPCODE:
         try {
-            Path path = store()->addToStore(baseNameOf(srcPath), srcPath, recursive, parseHashType(algo));
-            XPUSHs(sv_2mortal(newSVpv(path.c_str(), 0)));
+            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, recursive, parseHashType(algo));
+            XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -286,8 +285,8 @@ SV * makeFixedOutputPath(int recursive, char * algo, char * hash, char * name)
     PPCODE:
         try {
             Hash h(hash, parseHashType(algo));
-            Path path = store()->makeFixedOutputPath(recursive, h, name);
-            XPUSHs(sv_2mortal(newSVpv(path.c_str(), 0)));
+            auto path = store()->makeFixedOutputPath(recursive, h, name);
+            XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
         }
@@ -298,35 +297,35 @@ SV * derivationFromPath(char * drvPath)
         HV *hash;
     CODE:
         try {
-            Derivation drv = store()->derivationFromPath(drvPath);
+            Derivation drv = store()->derivationFromPath(store()->parseStorePath(drvPath));
             hash = newHV();
 
             HV * outputs = newHV();
-            for (DerivationOutputs::iterator i = drv.outputs.begin(); i != drv.outputs.end(); ++i)
-                hv_store(outputs, i->first.c_str(), i->first.size(), newSVpv(i->second.path.c_str(), 0), 0);
+            for (auto & i : drv.outputs)
+                hv_store(outputs, i.first.c_str(), i.first.size(), newSVpv(store()->printStorePath(i.second.path).c_str(), 0), 0);
             hv_stores(hash, "outputs", newRV((SV *) outputs));
 
             AV * inputDrvs = newAV();
-            for (DerivationInputs::iterator i = drv.inputDrvs.begin(); i != drv.inputDrvs.end(); ++i)
-                av_push(inputDrvs, newSVpv(i->first.c_str(), 0)); // !!! ignores i->second
+            for (auto & i : drv.inputDrvs)
+                av_push(inputDrvs, newSVpv(store()->printStorePath(i.first).c_str(), 0)); // !!! ignores i->second
             hv_stores(hash, "inputDrvs", newRV((SV *) inputDrvs));
 
             AV * inputSrcs = newAV();
-            for (PathSet::iterator i = drv.inputSrcs.begin(); i != drv.inputSrcs.end(); ++i)
-                av_push(inputSrcs, newSVpv(i->c_str(), 0));
+            for (auto & i : drv.inputSrcs)
+                av_push(inputSrcs, newSVpv(store()->printStorePath(i).c_str(), 0));
             hv_stores(hash, "inputSrcs", newRV((SV *) inputSrcs));
 
             hv_stores(hash, "platform", newSVpv(drv.platform.c_str(), 0));
             hv_stores(hash, "builder", newSVpv(drv.builder.c_str(), 0));
 
             AV * args = newAV();
-            for (Strings::iterator i = drv.args.begin(); i != drv.args.end(); ++i)
-                av_push(args, newSVpv(i->c_str(), 0));
+            for (auto & i : drv.args)
+                av_push(args, newSVpv(i.c_str(), 0));
             hv_stores(hash, "args", newRV((SV *) args));
 
             HV * env = newHV();
-            for (StringPairs::iterator i = drv.env.begin(); i != drv.env.end(); ++i)
-                hv_store(env, i->first.c_str(), i->first.size(), newSVpv(i->second.c_str(), 0), 0);
+            for (auto & i : drv.env)
+                hv_store(env, i.first.c_str(), i.first.size(), newSVpv(i.second.c_str(), 0), 0);
             hv_stores(hash, "env", newRV((SV *) env));
 
             RETVAL = newRV_noinc((SV *)hash);
@@ -340,7 +339,7 @@ SV * derivationFromPath(char * drvPath)
 void addTempRoot(char * storePath)
     PPCODE:
         try {
-            store()->addTempRoot(storePath);
+            store()->addTempRoot(store()->parseStorePath(storePath));
         } catch (Error & e) {
             croak("%s", e.what());
         }