Add original unix v6

source/s2/mesg.c

@@ -0,0 +1,49 @@
+/*
+ * mesg -- set current tty to accept or
+ *	forbid write permission.
+ *
+ *	mesg [y] [n]
+ *		y allow messages
+ *		n forbid messages
+ */
+
+int	sbuf[40];
+
+main(argc, argv)
+char *argv[];
+{
+	register char *tty;
+
+	tty = "/dev/ttyx";
+	tty[8] = ttyn(1);
+	if(stat(tty, sbuf) < 0) {
+		write(2, "cannot stat\n", 12);
+		exit(1);
+	}
+	if(argc < 2) {
+		if(sbuf[2] & 02)
+			goto no;
+		goto yes;
+	}
+	if(*argv[1] == 'y')
+		goto yes;
+
+no:
+	if(chmod(tty, 0600) < 0)
+		goto bad;
+	goto was;
+
+yes:
+	if(chmod(tty, 0622) < 0)
+		goto bad;
+
+was:
+	if(sbuf[2] & 02)
+		write(2, "was y\n", 6); else
+		write(2, "was n\n", 6);
+	exit(0);
+
+bad:
+	write(2, "cannot change mode\n", 19);
+	exit(1);
+}