1 files changed, 31 insertions, 0 deletions
diff --git a/src/libfetchers/fetchers.hh b/src/libfetchers/fetchers.hh
index 2bb4248be..40f2b6294 100644
--- a/src/libfetchers/fetchers.hh
+++ b/src/libfetchers/fetchers.hh
@@ -159,6 +159,37 @@ struct InputScheme
         std::optional<std::string> commitMsg) const;
 
     virtual std::pair<StorePath, Input> fetch(ref<Store> store, const Input & input) = 0;
+
+protected:
+    void emplaceURLQueryIntoAttrs(
+        const ParsedURL & parsedURL,
+        Attrs & attrs,
+        const StringSet & numericParams,
+        const StringSet & booleanParams) const
+    {
+        for (auto &[name, value] : parsedURL.query) {
+            if (name == "url") {
+                throw BadURL(
+                    "URL '%s' must not override url via query param!",
+                    parsedURL.to_string()
+                );
+            } else if (numericParams.count(name) != 0) {
+                if (auto n = string2Int<uint64_t>(value)) {
+                    attrs.insert_or_assign(name, *n);
+                } else {
+                    throw BadURL(
+                        "URL '%s' has non-numeric parameter '%s'",
+                        parsedURL.to_string(),
+                        name
+                    );
+                }
+            } else if (booleanParams.count(name) != 0) {
+                attrs.emplace(name, Explicit<bool> { value == "1" });
+            } else {
+                attrs.emplace(name, value);
+            }
+        }
+    }
 };
 
 void registerInputScheme(std::shared_ptr<InputScheme> && fetcher);