tty: Retire zombie dtrwait

Nothing uses dtrwait anymore. This was elimianted with the tty mpsafe
rewrite for FreeBSD 8. Only these zombie symbols and functionality
remain. GC them. Add comcontrol to the list things to remove in 16.0.

Sponsored by:		Netflix
Reviewed by:		kevans, emaste
Differential Revision:	https://reviews.freebsd.org/D52317

sbin/comcontrol/comcontrol.8

@@ -1,13 +1,17 @@
-.Dd May 15, 1994
+.Dd August 31, 2025
 .Dt COMCONTROL 8
 .Os
 .Sh NAME
 .Nm comcontrol
 .Nd control a special tty device
+.Sh DEPRECATION NOTICE
+The
+.Nm
+utility is deprecated and will be removed in
+.Fx 16.0 .
 .Sh SYNOPSIS
 .Nm
 .Ar special_device
-.Op dtrwait Ar number
 .Op drainwait Ar number
 .Sh DESCRIPTION
 The
@@ -22,13 +26,6 @@ Only the superuser can change the settings.
 .Pp
 The following options are available:
 .Bl -tag -width indent
-.It Cm dtrwait Ar number
-Set the time to wait after dropping DTR
-to the given number.
-The units are hundredths of a second.
-The default is 300 hundredths, i.e., 3 seconds.
-This option needed mainly to set proper recover time after
-modem reset.
 .It Cm drainwait Ar number
 Set the time to wait for output drain
 to the given number.
@@ -57,7 +54,6 @@ dialout devices
 Originally part of cgd's com package patches, version 0.2.1, to
 .Bx 386 0.1 .
 Once controlled bidirectional capabilities.
-Little is left to control now
-that these capabilities are standard.
+Little is left to control now that these capabilities are standard.
 .Sh AUTHORS
 .An Christopher G. Demetriou

sbin/comcontrol/comcontrol.c

@@ -46,7 +46,7 @@ static void
 usage(void)
 {
 	fprintf(stderr,
-	"usage: comcontrol <filename> [dtrwait <n>] [drainwait <n>]\n");
+	"usage: comcontrol <filename> [drainwait <n>]\n");
 	exit(1);
 }
 
@@ -55,8 +55,8 @@ main(int argc, char *argv[])
 {
 	int	fd;
 	int     res = 0;
-	int     print_dtrwait = 1, print_drainwait = 1;
-	int     dtrwait = -1, drainwait = -1;
+	int     print_drainwait = 1;
+	int     drainwait = -1;
 
 	if (argc < 2)
 		usage();
@@ -71,13 +71,6 @@ main(int argc, char *argv[])
 		}
 	}
 	if (argc == 2) {
-		if (ioctl(fd, TIOCMGDTRWAIT, &dtrwait) < 0) {
-			print_dtrwait = 0;
-			if (errno != ENOTTY) {
-				res = 1;
-				warn("TIOCMGDTRWAIT");
-			}
-		}
 		if (ioctl(fd, TIOCGDRAINWAIT, &drainwait) < 0) {
 			print_drainwait = 0;
 			if (errno != ENOTTY) {
@@ -85,21 +78,12 @@ main(int argc, char *argv[])
 				warn("TIOCGDRAINWAIT");
 			}
 		}
-		if (print_dtrwait)
-			printf("dtrwait %d ", dtrwait);
 		if (print_drainwait)
 			printf("drainwait %d ", drainwait);
 		printf("\n");
 	} else {
 		while (argv[2] != NULL) {
-			if (!strcmp(argv[2],"dtrwait")) {
-				if (dtrwait >= 0)
-					usage();
-				if (argv[3] == NULL || !isdigit(argv[3][0]))
-					usage();
-				dtrwait = atoi(argv[3]);
-				argv += 2;
-			} else if (!strcmp(argv[2],"drainwait")) {
+			if (!strcmp(argv[2],"drainwait")) {
 				if (drainwait >= 0)
 					usage();
 				if (argv[3] == NULL || !isdigit(argv[3][0]))
@@ -109,12 +93,6 @@ main(int argc, char *argv[])
 			} else
 				usage();
 		}
-		if (dtrwait >= 0) {
-			if (ioctl(fd, TIOCMSDTRWAIT, &dtrwait) < 0) {
-				res = 1;
-				warn("TIOCMSDTRWAIT");
-			}
-		}
 		if (drainwait >= 0) {
 			if (ioctl(fd, TIOCSDRAINWAIT, &drainwait) < 0) {
 				res = 1;

sys/sys/ttycom.h

@@ -69,8 +69,8 @@
 						/* 89-91 conflicts: tun and tap */
 #define	TIOCTIMESTAMP	_IOR('t', 89, struct timeval)	/* enable/get timestamp
 						 * of last input event */
-#define	TIOCMGDTRWAIT	_IOR('t', 90, int)	/* modem: get wait on close */
-#define	TIOCMSDTRWAIT	_IOW('t', 91, int)	/* modem: set wait on close */
+/*	TIOCMGDTRWAIT	_IOR('t', 90, int)	 * was modem: get wait on close */
+/*	TIOCMSDTRWAIT	_IOW('t', 91, int)	 * was modem: set wait on close */
 						/* 92-93 tun and tap */
 						/* 94-97 conflicts: tun and tap */
 #define	TIOCDRAIN	 _IO('t', 94)		/* wait till output drained */