MFC r315733, r315737, r315740, r330054:

 r315733 (imp):
  Impelemnt ttys onifexists in init.

  Implement a new init(8) option in /etc/ttys. If this option is present
  on the entry in /etc/ttys, the entry will be active if and only if it
  exists.  If the name starts with a '/', it will be considered an
  absolute path. If not, it will be a path relative to /dev.

  This allows one to turn off video console getty that aren't present
  (while running a getty on them even when they aren't the system
  console). Likewise with serial ports.

  It differs from onifconsole in only requiring the device exist rather
  than it be listed as one of the system consoles.

 r315737 (ngie):
  Unbreak world by adding sys/stat.h for stat(2)

 r315740 (imp):
  Simplify the code a little.

 r330054 (trasz):
  Improve missing tty handling in init(8).  This removes a check that did
  nothing - it was checking for ENXIO, which, with devfs, is no longer
  returned - and was badly placed anyway, and replaces it with similar
  one that works, and is done just before starting getty, instead of being
  done when rereading ttys(5).

  From the practical point of view, this makes init(8) handle disappearing
  terminals (eg /dev/ttyU*) gracefully, without unneccessary getty restarts
  and resulting error messages.

Reported by:	Bart Ender, Andre Albsmeier
PR:		228315
Blocks:		11.2-BETA2
Approved by:	re (marius)
Sponsored by:	The FreeBSD Foundation

2 files changed, 34 insertions, 4 deletions

diff --git a/lib/libc/gen/getttyent.3 b/lib/libc/gen/getttyent.3
index 18c3f07..43b2ace 100644
--- a/lib/libc/gen/getttyent.3
+++ b/lib/libc/gen/getttyent.3
@@ -75,6 +75,8 @@ struct ttyent {
 #define	TTY_SECURE	0x02	/* allow uid of 0 to login */
 #define	TTY_DIALUP	0x04	/* is a dialup tty */
 #define	TTY_NETWORK	0x08	/* is a network tty */
+#define	TTY_IFEXISTS	0x10	/* configured as "onifexists" */
+#define	TTY_IFCONSOLE	0x20	/* configured as "onifconsole" */
 	int	ty_status;	/* status flags */
 	char	*ty_window;	/* command to start up window manager */
 	char	*ty_comment;	/* comment field */
@@ -115,6 +117,10 @@ Identifies a tty used for network connections.
 If this flag is set, then
 .Fn isnettty
 will return a non-zero value.
+.It Dv TTY_IFEXISTS
+Identifies a tty that does not neccessarily exist.
+.It Dv TTY_IFCONSOLE
+Identifies a tty that might be a system console.
 .El
 .It Fa ty_window
 The command to execute for a window system associated with the line.
diff --git a/lib/libc/gen/getttyent.c b/lib/libc/gen/getttyent.c
index 266f631..e0b2698 100644
--- a/lib/libc/gen/getttyent.c
+++ b/lib/libc/gen/getttyent.c
@@ -34,6 +34,7 @@ static char sccsid[] = "@(#)getttyent.c	8.1 (Berkeley) 6/4/93";
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/sysctl.h>
 
 #include <ctype.h>
@@ -72,11 +73,14 @@ auto_tty_status(const char *ty_name)
 {
 	size_t len;
 	char *buf, *cons, *nextcons;
+	int rv;
+
+	rv = TTY_IFCONSOLE;
 
 	/* Check if this is an enabled kernel console line */
 	buf = NULL;
 	if (sysctlbyname("kern.console", NULL, &len, NULL, 0) == -1)
-		return (0); /* Errors mean don't enable */
+		return (rv); /* Errors mean don't enable */
 	buf = malloc(len);
 	if (sysctlbyname("kern.console", buf, &len, NULL, 0) == -1)
 		goto done;
@@ -87,14 +91,32 @@ auto_tty_status(const char *ty_name)
 	nextcons = buf;
 	while ((cons = strsep(&nextcons, ",")) != NULL && strlen(cons) != 0) {
 		if (strcmp(cons, ty_name) == 0) {
-			free(buf);
-			return (TTY_ON);
+			rv |= TTY_ON;
+			break;
 		}
 	}
 
 done:
 	free(buf);
-	return (0);
+	return (rv);
+}
+
+static int
+auto_exists_status(const char *ty_name)
+{
+	struct stat sb;
+	char *dev;
+	int rv;
+
+	rv = TTY_IFEXISTS;
+	if (*ty_name == '/')
+		asprintf(&dev, "%s", ty_name);
+	else
+		asprintf(&dev, "/dev/%s", ty_name);
+	if (dev != NULL && stat(dev, &sb) == 0)
+		rv |= TTY_ON;
+	free(dev);
+	return (rv);
 }
 
 struct ttyent *
@@ -161,6 +183,8 @@ getttyent(void)
 			tty.ty_status |= TTY_ON;
 		else if (scmp(_TTYS_ONIFCONSOLE))
 			tty.ty_status |= auto_tty_status(tty.ty_name);
+		else if (scmp(_TTYS_ONIFEXISTS))
+			tty.ty_status |= auto_exists_status(tty.ty_name);
 		else if (scmp(_TTYS_SECURE))
 			tty.ty_status |= TTY_SECURE;
 		else if (scmp(_TTYS_INSECURE))