+static NORETURN void die_builtin(const char *err, va_list params)
+{
+ report("fatal: ", err, params);
+ exit(128);
+}
+
+static void error_builtin(const char *err, va_list params)
+{
+ report("error: ", err, params);
+}
+
+static void warn_builtin(const char *warn, va_list params)
+{
+ report("warning: ", warn, params);
+}
+
+/* If we are in a dlopen()ed .so write to a global variable would segfault
+ * (ugh), so keep things static. */
+static void (*usage_routine)(const char *err) NORETURN = usage_builtin;
+static void (*die_routine)(const char *err, va_list params) NORETURN = die_builtin;
+static void (*error_routine)(const char *err, va_list params) = error_builtin;
+static void (*warn_routine)(const char *err, va_list params) = warn_builtin;
+
+void set_usage_routine(void (*routine)(const char *err) NORETURN)
+{
+ usage_routine = routine;
+}
+
+void set_die_routine(void (*routine)(const char *err, va_list params) NORETURN)
+{
+ die_routine = routine;
+}
+
+void set_error_routine(void (*routine)(const char *err, va_list params))
+{
+ error_routine = routine;
+}
+
+void set_warn_routine(void (*routine)(const char *warn, va_list params))
+{
+ warn_routine = routine;
+}
+
+
+void usage(const char *err)
+{
+ usage_routine(err);
+}
+