+ ucwlib_lock();
+ if (!sig_handler_nest[signum]++)
+ {
+ struct sigaction act;
+ bzero(&act, sizeof(act));
+ act.sa_handler = signal_handler_internal;
+ act.sa_flags = SA_NODEFER;
+ if (sigaction(signum, &act, &sig_handler_old[signum]) < 0)
+ die("sigaction: %m");
+ }
+ ucwlib_unlock();
+}
+
+void
+unhandle_signal(int signum)
+{
+ ucwlib_lock();
+ ASSERT(sig_handler_nest[signum]);
+ if (!--sig_handler_nest[signum])
+ {
+ if (sigaction(signum, &sig_handler_old[signum], NULL) < 0)
+ die("sigaction: %m");
+ }
+ ucwlib_unlock();
+}
+
+sh_sighandler_t
+set_signal_handler(int signum, sh_sighandler_t new)
+{
+ struct ucwlib_context *ctx = ucwlib_thread_context();
+ if (!ctx->signal_handlers)
+ ctx->signal_handlers = xmalloc_zero(NSIG * sizeof(sh_sighandler_t));
+ sh_sighandler_t old = ctx->signal_handlers[signum];
+ ctx->signal_handlers[signum] = new;
+ return old;