Refactor into _extract_tarballname helper function

pyodide_build/buildpkg.py

@@ -59,6 +59,20 @@ def _make_whlfile(
 )
 
 
+def _extract_tarballname(url: str, headers: dict) -> str:
+    tarballname = url.split("/")[-1]
+
+    if "Content-Disposition" in headers:
+        msg = Message()
+        msg["Content-Disposition"] = headers["Content-Disposition"]
+
+        filename = msg.get_filename()
+        if filename is not None:
+            tarballname = filename
+
+    return tarballname
+
+
 class RecipeBuilder:
     """
     A class to build a Pyodide meta.yaml recipe.
@@ -323,14 +337,7 @@ def _download_and_extract(self) -> None:
 
         self.build_dir.mkdir(parents=True, exist_ok=True)
 
-        tarballname = url.split("/")[-1]
-        if "Content-Disposition" in response.headers:
-            msg = Message()
-            msg["Content-Disposition"] = response.headers["Content-Disposition"]
-            filename = msg.get_filename()
-            if filename is not None:
-                tarballname = filename
-
+        tarballname = _extract_tarballname(url, response.headers)
         tarballpath = self.build_dir / tarballname
         tarballpath.write_bytes(response.content)