Return map of StorePaths in copyPaths

This allows the caller to know what values were actually added to the
store.

src/libstore/store-api.cc

@@ -638,7 +638,7 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
 }
 
 
-void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & storePaths,
+std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & storePaths,
     RepairFlag repair, CheckSigsFlag checkSigs, SubstituteFlag substitute)
 {
     auto valid = dstStore->queryValidPaths(storePaths, substitute);
@@ -647,7 +647,11 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
     for (auto & path : storePaths)
         if (!valid.count(path)) missing.insert(srcStore->printStorePath(path));
 
-    if (missing.empty()) return;
+    std::map<StorePath, StorePath> pathsMap;
+    for (auto & path : storePaths)
+        pathsMap.insert_or_assign(path, path);
+
+    if (missing.empty()) return pathsMap;
 
     Activity act(*logger, lvlInfo, actCopyPaths, fmt("copying %d paths", missing.size()));
 
@@ -677,6 +681,7 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
                 if (storePathForDst != storePath)
                     debug("replaced path '%s' to '%s' for substituter '%s'", srcStore->printStorePath(storePath), dstStore->printStorePath(storePathForDst), dstStore->getUri());
             }
+            pathsMap.insert_or_assign(storePath, storePathForDst);
 
             if (dstStore->isValidPath(storePathForDst)) {
                 nrDone++;
@@ -704,6 +709,7 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
                 if (storePathForDst != storePath)
                     debug("replaced path '%s' to '%s' for substituter '%s'", srcStore->printStorePath(storePath), dstStore->printStorePath(storePathForDst), dstStore->getUri());
             }
+            pathsMap.insert_or_assign(storePath, storePathForDst);
 
             if (!dstStore->isValidPath(storePathForDst)) {
                 MaintainCount<decltype(nrRunning)> mc(nrRunning);
@@ -723,6 +729,8 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & st
             nrDone++;
             showProgress();
         });
+
+    return pathsMap;
 }
 
 

src/libstore/store-api.hh

@@ -444,8 +444,9 @@ public:
     virtual StorePathSet querySubstitutablePaths(const StorePathSet & paths) { return {}; };
 
     /* Query substitute info (i.e. references, derivers and download
-       sizes) of a set of paths.  If a path does not have substitute
+       sizes) of a map of paths to their optional ca values. If a path
-       info, it's omitted from the resulting ‘infos’ map. */
+       does not have substitute info, it's omitted from the resulting
+       ‘infos’ map. */
     virtual void querySubstitutablePathInfos(const StorePathCAMap & paths,
         SubstitutablePathInfos & infos) { return; };
 
@@ -743,11 +744,13 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
 
 
 /* Copy store paths from one store to another. The paths may be copied
-   in parallel. They are copied in a topologically sorted order
+   in parallel. They are copied in a topologically sorted order (i.e.
-   (i.e. if A is a reference of B, then A is copied before B), but
+   if A is a reference of B, then A is copied before B), but the set
-   the set of store paths is not automatically closed; use
+   of store paths is not automatically closed; use copyClosure() for
-   copyClosure() for that. */
+   that. Returns a map of what each path was copied to the dstStore
-void copyPaths(ref<Store> srcStore, ref<Store> dstStore, const StorePathSet & storePaths,
+   as. */
+std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStore,
+    const StorePathSet & storePaths,
     RepairFlag repair = NoRepair,
     CheckSigsFlag checkSigs = CheckSigs,
     SubstituteFlag substitute = NoSubstitute);