Allow the redraw method to be chosen by the user, and include the old Ctrl L

character method again.

attach.c

@@ -96,7 +96,7 @@ process_kbd(int s, struct packet *pkt)
 	{
 		/* Tell the master that we are suspending. */
 		pkt->type = MSG_DETACH;
-		write(s, pkt, sizeof(*pkt));
+		write(s, pkt, sizeof(struct packet));
 
 		/* And suspend... */
 		tcsetattr(0, TCSADRAIN, &orig_term);
@@ -106,8 +106,13 @@ process_kbd(int s, struct packet *pkt)
 
 		/* Tell the master that we are returning. */
 		pkt->type = MSG_ATTACH;
+		write(s, pkt, sizeof(struct packet));
+
+		/* We would like a redraw, too. */
+		pkt->type = MSG_REDRAW;
+		pkt->len = redraw_method;
 		ioctl(0, TIOCGWINSZ, &pkt->u.ws);
-		write(s, pkt, sizeof(*pkt));
+		write(s, pkt, sizeof(struct packet));
 		return;
 	}
 	/* Detach char? */
@@ -121,7 +126,7 @@ process_kbd(int s, struct packet *pkt)
 		win_changed = 1;
 
 	/* Push it out */
-	write(s, pkt, sizeof(*pkt));
+	write(s, pkt, sizeof(struct packet));
 }
 
 int
@@ -176,8 +181,13 @@ attach_main(int noerror)
 
 	/* Tell the master that we want to attach. */
 	pkt.type = MSG_ATTACH;
+	write(s, &pkt, sizeof(struct packet));
+
+	/* We would like a redraw, too. */
+	pkt.type = MSG_REDRAW;
+	pkt.len = redraw_method;
 	ioctl(0, TIOCGWINSZ, &pkt.u.ws);
-	write(s, &pkt, sizeof(pkt));
+	write(s, &pkt, sizeof(struct packet));
 
 	/* Wait for things to happen */
 	while (1)

dtach.h

@@ -74,15 +74,24 @@
 #include <sys/un.h>
 
 extern char *progname, *sockname;
-extern int detach_char, no_suspend;
+extern int detach_char, no_suspend, redraw_method;
 extern struct termios orig_term;
 
 enum
 {
-	MSG_PUSH,
-	MSG_ATTACH,
-	MSG_DETACH,
-	MSG_WINCH,
+	MSG_PUSH	= 0,
+	MSG_ATTACH	= 1,
+	MSG_DETACH	= 2,
+	MSG_WINCH	= 3,
+	MSG_REDRAW	= 4,
+};
+
+enum
+{
+	REDRAW_UNSPEC	= 0,
+	REDRAW_NONE	= 1,
+	REDRAW_CTRL_L	= 2,
+	REDRAW_WINCH	= 3,
 };
 
 /* The client to master protocol. */

main.c

@@ -35,6 +35,8 @@ char *sockname;
 int detach_char = '\\' - 64;
 /* 1 if we should not interpret the suspend character. */
 int no_suspend;
+/* The default redraw method. Initially set to unspecified. */
+int redraw_method = REDRAW_UNSPEC;
 
 /*
 ** The original terminal settings. Shared between the master and attach
@@ -63,6 +65,10 @@ usage()
 		"  -e <char>\tSet the detach character to <char>, defaults "
 		"to ^\\.\n"
 		"  -E\t\tDisable the detach character.\n"
+		"  -r <method>\tUse the specified redraw method when redrawing:\n"
+		"\t\t     none: Don't redraw at all.\n"
+		"\t\t   ctrl_l: Send a Ctrl L character to the program.\n"
+		"\t\t    winch: Send a WINCH signal to the program.\n"
 		"  -z\t\tDisable processing of the suspend key.\n"
 		"\nReport any bugs to <" PACKAGE_BUGREPORT ">.\n",
 		PACKAGE_VERSION, __DATE__, __TIME__);
@@ -153,6 +159,33 @@ main(int argc, char **argv)
 					detach_char = argv[0][0];
 				break;
 			}
+			else if (*p == 'r')
+			{
+				++argv; --argc;
+				if (argc < 1)
+				{
+					printf("%s: No redraw method "
+						"specified.\n", progname);	
+					printf("Try '%s --help' for more "
+						"information.\n", progname);
+					return 1;
+				}
+				if (strcmp(argv[0], "none") == 0)
+					redraw_method = REDRAW_NONE;
+				else if (strcmp(argv[0], "ctrl_l") == 0)
+					redraw_method = REDRAW_CTRL_L;
+				else if (strcmp(argv[0], "winch") == 0)
+					redraw_method = REDRAW_WINCH;
+				else
+				{
+					printf("%s: Invalid redraw method "
+						"specified.\n", progname);	
+					printf("Try '%s --help' for more "
+						"information.\n", progname);
+					return 1;
+				}
+				break;
+			}
 			else
 			{
 				printf("%s: Invalid option '-%c'\n",

master.c

@@ -238,7 +238,7 @@ client_activity(struct client *p)
 	struct packet pkt;
 
 	/* Read the activity. */
-	len = read(p->fd, &pkt, sizeof(pkt));
+	len = read(p->fd, &pkt, sizeof(struct packet));
 	/* Close the client on an error. */
 	if (len <= 0)
 	{
@@ -254,24 +254,9 @@ client_activity(struct client *p)
 	if (pkt.type == MSG_PUSH)
 		write(the_pty.fd, pkt.u.buf, pkt.len);
 
-	/* When attaching, we set the window size and force a redraw by sending
-	** the WINCH signal to the program.
-	**
-	** XXX: Are there any programs that don't handle the WINCH signal
-	** properly? Full-screen programs should fully redraw themselves, and
-	** line-oriented programs should redraw the prompt, or do nothing. 
-	*/
+	/* Attach or detach from the program. */
 	else if (pkt.type == MSG_ATTACH)
-	{
 		p->attached = 1;
-		if (memcmp(&the_pty.ws, &pkt.u.ws, sizeof(struct winsize)) != 0)
-		{
-			the_pty.ws = pkt.u.ws;
-			ioctl(the_pty.fd, TIOCSWINSZ, &the_pty.ws);
-		}
-		else
-			killpty(&the_pty, SIGWINCH);
-	}
 	else if (pkt.type == MSG_DETACH)
 		p->attached = 0;
 
@@ -281,6 +266,41 @@ client_activity(struct client *p)
 		the_pty.ws = pkt.u.ws;
 		ioctl(the_pty.fd, TIOCSWINSZ, &the_pty.ws);
 	}
+
+	/* Force a redraw using a particular method. */
+	else if (pkt.type == MSG_REDRAW)
+	{
+		int method = pkt.len;
+
+		/* If the client didn't specify a particular method, use
+		** whatever we had on startup. */
+		if (method == REDRAW_UNSPEC)
+			method = redraw_method;
+		if (method == REDRAW_NONE)
+			return;
+
+		/* Set the window size. */
+		the_pty.ws = pkt.u.ws;
+		ioctl(the_pty.fd, TIOCSWINSZ, &the_pty.ws);
+
+		/* Send a ^L character if the terminal is in no-echo and
+		** character-at-a-time mode. */
+		if (method == REDRAW_CTRL_L)
+		{
+			char c = '\f';
+
+                	if (((the_pty.term.c_lflag & (ECHO|ICANON)) == 0) &&
+                        	(the_pty.term.c_cc[VMIN] == 1))
+			{
+				write(the_pty.fd, &c, 1);
+			}
+		}
+		/* Send a WINCH signal to the program. */
+		else if (method == REDRAW_WINCH)
+		{
+			killpty(&the_pty, SIGWINCH);
+		}
+	}
 }
 
 /* The master process - It watches over the pty process and the attached */
@@ -368,6 +388,10 @@ master_main(char **argv)
 	int s;
 	pid_t pid;
 
+	/* Use a default redraw method if one hasn't been specified yet. */
+	if (redraw_method == REDRAW_UNSPEC)
+		redraw_method = REDRAW_CTRL_L;
+
 	/* Create the unix domain socket. */
 	s = create_socket(sockname);
 	if (s < 0)