From ff48be37b5e0fe277eaf8a46c732ea5e484bab9c Mon Sep 17 00:00:00 2001
From: David Bright <dab@FreeBSD.org>
Date: Thu, 7 Sep 2017 00:20:17 +0000
Subject: [PATCH] Add a new getty/gettytab capability to generate an initial
 message dynamically.

This modification adds a new gettytab(5) option (iM) to specify a
program to run that will generate the initial (banner) message that is
displayed before the login prompt. Such a capability is useful when
dynamic information is needed in the banner message that cannot be
supplied by the set of % substitution sequences available in the "im"
option.

Reviewed by:	vangyzen, wblock, manpages
Approved by:	vangyzen (mentor)
MFC after:	1 week
Relnotes:	yes
Sponsored by:	Dell EMC
Differential Revision:	https://reviews.freebsd.org/D12108
---
 libexec/getty/gettytab.5 | 6 ++++--
 libexec/getty/gettytab.h | 1 +
 libexec/getty/init.c     | 1 +
 libexec/getty/main.c     | 2 ++
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/libexec/getty/gettytab.5 b/libexec/getty/gettytab.5
index 0011f3ac65ad..b1ddda2dd5c3 100644
--- a/libexec/getty/gettytab.5
+++ b/libexec/getty/gettytab.5
@@ -28,7 +28,7 @@
 .\"     from: @(#)gettytab.5	8.4 (Berkeley) 4/19/94
 .\" $FreeBSD$
 .\" "
-.Dd February 2, 2017
+.Dd August 23, 2017
 .Dt GETTYTAB 5
 .Os
 .Sh NAME
@@ -130,6 +130,8 @@ hangup line on last close
 .It "ig	bool	false	ignore garbage characters in login name"
 .It "im	str" Ta Dv NULL
 .Ta No "initial (banner) message"
+.It "iM	str" Ta Dv NULL
+.Ta No "execute named file to generate initial (banner) message"
 .It "in	str" Ta So Li ^C
 .Sc Ta No "interrupt character"
 .It "is	num	unused	input speed"
@@ -146,7 +148,7 @@ hangup line on last close
 .It "mb	bool	false	do flow control based on carrier"
 .It "nc	bool	false	terminal does not supply carrier (set clocal)"
 .It "nl	bool	false	terminal has (or might have) a newline character"
-.It "np	bool	false	terminal uses no parity (i.e. 8-bit characters)"
+.It "np	bool	false	terminal uses no parity (i.e., 8-bit characters)"
 .It "nx	str	default	next table (for auto speed selection)"
 .It "o0	num	unused	tty output flags to write messages"
 .It "o1	num	unused	tty output flags to read login name"
diff --git a/libexec/getty/gettytab.h b/libexec/getty/gettytab.h
index 67ad95fa1768..83b17f013740 100644
--- a/libexec/getty/gettytab.h
+++ b/libexec/getty/gettytab.h
@@ -88,6 +88,7 @@ struct gettyflags {
 #define AC	gettystrs[28].value
 #define AL	gettystrs[29].value
 #define DF	gettystrs[30].value
+#define IMP	gettystrs[31].value
 
 /*
  * Numeric definitions.
diff --git a/libexec/getty/init.c b/libexec/getty/init.c
index 6959e8d56235..a7077a332665 100644
--- a/libexec/getty/init.c
+++ b/libexec/getty/init.c
@@ -82,6 +82,7 @@ struct	gettystrs gettystrs[] = {
 	{ "ac" },			/* modem answer-chat */
 	{ "al" },			/* user to auto-login */
 	{ "df", datefmt},		/* format for strftime() */
+	{ "iM" },			/* initial message program */
 	{ 0 }
 };
 
diff --git a/libexec/getty/main.c b/libexec/getty/main.c
index 94ecb0779cec..9b2c964873bf 100644
--- a/libexec/getty/main.c
+++ b/libexec/getty/main.c
@@ -324,6 +324,8 @@ main(int argc, char *argv[])
 		}
 		first_time = 0;
 
+		if (IMP && *IMP && !(PL && PP))
+			system(IMP);
 		if (IM && *IM && !(PL && PP))
 			putf(IM);
 		if (setjmp(timeout)) {