1 files changed, 20 insertions, 16 deletions

diff --git a/src/libstore/profiles.hh b/src/libstore/profiles.hh
index 78645d8b6..d100c970c 100644
--- a/src/libstore/profiles.hh
+++ b/src/libstore/profiles.hh
@@ -8,38 +8,35 @@
 
 namespace nix {
 
+class StorePath;
+
+
+typedef uint64_t GenerationNumber;
 
 struct Generation
 {
-    int number;
+    GenerationNumber number;
     Path path;
     time_t creationTime;
-    Generation()
-    {
-        number = -1;
-    }
-    operator bool() const
-    {
-        return number != -1;
-    }
 };
 
-typedef list<Generation> Generations;
+typedef std::list<Generation> Generations;
 
 
 /* Returns the list of currently present generations for the specified
-   profile, sorted by generation number. */
-Generations findGenerations(Path profile, int & curGen);
+   profile, sorted by generation number. Also returns the number of
+   the current generation. */
+std::pair<Generations, std::optional<GenerationNumber>> findGenerations(Path profile);
 
 class LocalFSStore;
 
-Path createGeneration(ref<LocalFSStore> store, Path profile, Path outPath);
+Path createGeneration(ref<LocalFSStore> store, Path profile, StorePath outPath);
 
-void deleteGeneration(const Path & profile, unsigned int gen);
+void deleteGeneration(const Path & profile, GenerationNumber gen);
 
-void deleteGenerations(const Path & profile, const std::set<unsigned int> & gensToDelete, bool dryRun);
+void deleteGenerations(const Path & profile, const std::set<GenerationNumber> & gensToDelete, bool dryRun);
 
-void deleteGenerationsGreaterThan(const Path & profile, const int max, bool dryRun);
+void deleteGenerationsGreaterThan(const Path & profile, GenerationNumber max, bool dryRun);
 
 void deleteOldGenerations(const Path & profile, bool dryRun);
 
@@ -49,6 +46,13 @@ void deleteGenerationsOlderThan(const Path & profile, const string & timeSpec, b
 
 void switchLink(Path link, Path target);
 
+/* Roll back a profile to the specified generation, or to the most
+   recent one older than the current. */
+void switchGeneration(
+    const Path & profile,
+    std::optional<GenerationNumber> dstGen,
+    bool dryRun);
+
 /* Ensure exclusive access to a profile.  Any command that modifies
    the profile first acquires this lock. */
 void lockProfile(PathLocks & lock, const Path & profile);