+#ifndef SIGRETRO
+#define sigchild()
+#endif
+
+/*
+ * 4.2bsd signal interface help...
+ */
+#ifdef VMUNIX
+#define sigset(s, a) signal(s, a)
+#define sigsys(s, a) signal(s, a)
+#endif
+
+/*
+ * Truncate a file to the last character written. This is
+ * useful just before closing an old file that was opened
+ * for read/write.
+ */
+#define trunc(stream) ftruncate(fileno(stream), (long) ftell(stream))