Re: install/54932: A green message overwrite part of screen in sysinst on laptop

The following reply was made to PR install/54932; it has been noted by GNATS.

From: Andreas Gustafsson <[email protected]>
To: [email protected]
Cc: 
Subject: Re: install/54932: A green message overwrite part of screen in sysinst on laptop
Date: Sat, 27 Jun 2026 15:07:20 +0300

 A few weeks ago, I wrote:
 > Sysinst already intercepts kernel messages using TIOCCONS, but only while
 > running external commands.  It should intercept them at all times.
 
 I propose the following patch.
 
 Index: src/usr.sbin/sysinst/defs.h
 ===================================================================
 RCS file: /cvsroot/src/usr.sbin/sysinst/defs.h,v
 retrieving revision 1.95
 diff -u -r1.95 defs.h
 --- src/usr.sbin/sysinst/defs.h	26 Apr 2026 13:31:47 -0000	1.95
 +++ src/usr.sbin/sysinst/defs.h	15 Jun 2026 16:21:19 -0000
 @@ -919,6 +919,8 @@
  	    struct disk_partitions*);
  void	free_install_desc(struct install_partition_desc*);
  bool	may_swap_if_not_sdmmc(const char*);
 +void	redirect_console(int, int);
 +void	discard_console_output(void);
  
  /* from target.c */
  #if defined(DEBUG)  ||	defined(DEBUG_ROOT)
 Index: src/usr.sbin/sysinst/main.c
 ===================================================================
 RCS file: /cvsroot/src/usr.sbin/sysinst/main.c,v
 retrieving revision 1.36
 diff -u -r1.36 main.c
 --- src/usr.sbin/sysinst/main.c	26 Apr 2026 13:31:47 -0000	1.36
 +++ src/usr.sbin/sysinst/main.c	15 Jun 2026 16:21:19 -0000
 @@ -274,6 +274,9 @@
  		no_https = 1;
  	}
  
 +	/* Prevent kernel conole messages from messing up the display */
 +	discard_console_output();
 +
  	/* initialize message window */
  	if (menu_init()) {
  		__menu_initerror();
 Index: src/usr.sbin/sysinst/run.c
 ===================================================================
 RCS file: /cvsroot/src/usr.sbin/sysinst/run.c,v
 retrieving revision 1.16
 diff -u -r1.16 run.c
 --- src/usr.sbin/sysinst/run.c	4 Oct 2024 15:11:09 -0000	1.16
 +++ src/usr.sbin/sysinst/run.c	15 Jun 2026 16:21:19 -0000
 @@ -419,7 +419,6 @@
  	char *cp, *ncp;
  	struct termios rtt, tt;
  	struct timeval tmo;
 -	static int do_tioccons = 2;
  
  	(void)tcgetattr(STDIN_FILENO, &tt);
  	if (openpty(&master, &slave, NULL, &tt, win) == -1) {
 @@ -433,20 +432,7 @@
  	ttysig_ignore = 1;
  	ioctl(master, TIOCPKT, &ttysig_ignore);
  
 -	/* Try to get console output into our pipe */
 -	if (do_tioccons) {
 -		if (ioctl(slave, TIOCCONS, &do_tioccons) == 0
 -		    && do_tioccons == 2) {
 -			/* test our output - we don't want it grabbed */
 -			write(1, " \b", 2);
 -			ioctl(master, FIONREAD, &do_tioccons);
 -			if (do_tioccons != 0) {
 -				do_tioccons = 0;
 -				ioctl(slave, TIOCCONS, &do_tioccons);
 -			} else
 -				do_tioccons = 1;
 -		}
 -	}
 +	redirect_console(master, slave);
  
  	if (logfp)
  		fflush(logfp);
 @@ -589,6 +575,7 @@
  	}
  	close(master);
  	close(slave);
 +	discard_console_output();
  	if (logfp)
  		fflush(logfp);
  
 Index: src/usr.sbin/sysinst/util.c
 ===================================================================
 RCS file: /cvsroot/src/usr.sbin/sysinst/util.c,v
 retrieving revision 1.78
 diff -u -r1.78 util.c
 --- src/usr.sbin/sysinst/util.c	5 Aug 2025 14:52:43 -0000	1.78
 +++ src/usr.sbin/sysinst/util.c	15 Jun 2026 16:21:20 -0000
 @@ -193,6 +193,8 @@
     programs available on install media */
  int have_raid, have_vnd, have_cgd, have_lvm, have_gpt, have_dk;
  
 +int console_tty = -1;	/* tty where console is currently redirected */
 +
  /*
   * local prototypes
   */
 @@ -2682,3 +2684,48 @@
  	return strncmp(parent, "sdmmc", 5) != 0;
  }
  #endif
 +
 +/*
 + * Redirect console output to the pty associated with master/slave
 + */
 +void
 +redirect_console(int master, int slave) {
 +	static int do_tioccons = 2;
 +	/* Try to get console output into our pipe */
 +	if (do_tioccons) {
 +		/* Turn off any existing console redirection */
 +		if (console_tty != -1) {
 +			int off = 0;
 +			ioctl(console_tty, TIOCCONS, &off);
 +			console_tty = -1;
 +		}
 +		if (ioctl(slave, TIOCCONS, &do_tioccons) == 0) {
 +			console_tty = slave;
 +			if (do_tioccons == 2) {
 +				/* test our output - we don't want it grabbed */
 +				write(1, " \b", 2);
 +				ioctl(master, FIONREAD, &do_tioccons);
 +				if (do_tioccons != 0) {
 +					do_tioccons = 0;
 +					ioctl(slave, TIOCCONS, &do_tioccons);
 +					console_tty = -1;
 +				} else
 +					do_tioccons = 1;
 +			}
 +		}
 +	}
 +}
 +
 +/*
 + * Redirect console output to nowhere
 + */
 +void
 +discard_console_output(void) {
 +	static int master = -1, slave = -1;
 +	if (slave == -1)
 +		/* Return value ignored */
 +		openpty(&master, &slave, NULL, NULL, NULL);
 +	if (slave == -1)
 +		return;
 +	redirect_console(master, slave);
 +}