-extern int head_ref(each_ref_fn, void *);
-extern int for_each_ref(each_ref_fn, void *);
-extern int for_each_ref_in(const char *, each_ref_fn, void *);
-extern int for_each_tag_ref(each_ref_fn, void *);
-extern int for_each_branch_ref(each_ref_fn, void *);
-extern int for_each_remote_ref(each_ref_fn, void *);
-extern int for_each_replace_ref(each_ref_fn, void *);
-extern int for_each_glob_ref(each_ref_fn, const char *pattern, void *);
-extern int for_each_glob_ref_in(each_ref_fn, const char *pattern, const char* prefix, void *);
+extern int head_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data);
+extern int for_each_tag_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_branch_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_remote_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_replace_ref(each_ref_fn fn, void *cb_data);
+extern int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data);
+extern int for_each_glob_ref_in(each_ref_fn fn, const char *pattern, const char *prefix, void *cb_data);