1 files changed, 35 insertions, 0 deletions
diff --git a/src/libfetchers/mercurial.cc b/src/libfetchers/mercurial.cc
index 1d6571571..5abb00172 100644
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@@ -60,6 +60,41 @@ struct MercurialInput : Input
         return attrs;
     }
 
+    std::shared_ptr<const Input> applyOverrides(
+        std::optional<std::string> ref,
+        std::optional<Hash> rev) const override
+    {
+        if (!ref && !rev) return shared_from_this();
+
+        auto res = std::make_shared<MercurialInput>(*this);
+
+        if (ref) res->ref = ref;
+        if (rev) res->rev = rev;
+
+        return res;
+    }
+
+    std::optional<Path> getSourcePath() const
+    {
+        if (url.scheme == "file" && !ref && !rev)
+            return url.path;
+        return {};
+    }
+
+    void markChangedFile(std::string_view file, std::optional<std::string> commitMsg) const override
+    {
+        auto sourcePath = getSourcePath();
+        assert(sourcePath);
+
+        // FIXME: shut up if file is already tracked.
+        runProgram("hg", true,
+            { "add", *sourcePath + "/" + std::string(file) });
+
+        if (commitMsg)
+            runProgram("hg", true,
+                { "commit", *sourcePath + "/" + std::string(file), "-m", *commitMsg });
+    }
+
     std::pair<bool, std::string> getActualUrl() const
     {
         bool isLocal = url.scheme == "file";