#define UNLOCK(x) (*(x)=0)
#define CANCELPT(x) (libc.cancelpt ? libc.cancelpt((x)),0 : (void)(x),0)
#define CANCELPT_BEGIN CANCELPT(1)
-#define CANCELPT_END CANCELPT(0)
+#define CANCELPT_TRY CANCELPT(0)
+#define CANCELPT_END CANCELPT(-1)
extern char **__environ;
#define environ __environ