From cf4dcfa6727b89362494bd49e2a28ebd10d767ce Mon Sep 17 00:00:00 2001
From: Gaius Mulley <gaiusmod2@gmail.com>
Date: Tue, 16 May 2023 15:51:53 +0100
Subject: [PATCH] PR modula2/108344 disable default opening of /dev/tty

This patch changes removes the static initialisation code for KeyBoardLEDs.cc.
The module is only initialised if one of the exported functions is called.
This is useful as the module will access /dev/tty which might not be
available.  TimerHandler.mod has also been changed to disable the scroll
lock LED as a sign of life.

gcc/m2/ChangeLog:

	PR modula2/108344
	* gm2-libs-coroutines/TimerHandler.mod (EnableLED): New constant.
	(Timer): Test EnableLED before switching on the scroll LED.

libgm2/ChangeLog:

	PR modula2/108344
	* libm2cor/KeyBoardLEDs.cc (initialize_module): New function.
	(SwitchScroll): Call initialize_module.
	(SwitchNum): Call initialize_module.
	(SwitchCaps): Call initialize_module.
	(SwitchLEDs): Call initialize_module.
	(M2EXPORT): Remove initialization code.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>
---
 gcc/m2/gm2-libs-coroutines/TimerHandler.mod | 35 +++++++++++----------
 libgm2/libm2cor/KeyBoardLEDs.cc             | 31 ++++++++++++------
 2 files changed, 40 insertions(+), 26 deletions(-)

diff --git a/gcc/m2/gm2-libs-coroutines/TimerHandler.mod b/gcc/m2/gm2-libs-coroutines/TimerHandler.mod
index d3dee319ca1..1285873486d 100644
--- a/gcc/m2/gm2-libs-coroutines/TimerHandler.mod
+++ b/gcc/m2/gm2-libs-coroutines/TimerHandler.mod
@@ -41,8 +41,9 @@ CONST
    MaxQuantum     =     4 ;   (* Maximum ticks a process may consume    *)
                               (* before being rescheduled.              *)
    BaseTicks      = 1000000 ; (* Max resolution of clock ticks per sec  *)
-   TimerStackSize = 100000H ; (* Reasonable sized stack for a process  *)
-   Debugging      =  FALSE ;  (* Do you want lots of debugging info?   *)
+   TimerStackSize = 100000H ; (* Reasonable sized stack for a process   *)
+   Debugging      =  FALSE ;  (* Do you want lots of debugging info?    *)
+   EnableLED      =  FALSE ;  (* Should the scroll LED be pulsed?       *)
 
 TYPE
    EVENT = POINTER TO RECORD
@@ -328,21 +329,23 @@ BEGIN
       (* Now compenstate for lost ticks *)
       StartClock (TimerIntNo, CurrentCount + (BaseTicks DIV TicksPerSecond)) ;
 
-      (* your code needs to go here *)
-      INC (TotalTicks) ;                                     (* (iii) *)    (* remove for student *)
-      (* now pulse scroll LED *)                                            (* remove for student *)
-      IF (TotalTicks MOD TicksPerSecond) = 0                                (* remove for student *)
-      THEN                                                                  (* remove for student *)
-         ScrollLED := NOT ScrollLED ;                                       (* remove for student *)
-         (* r := printf("<scroll %d>", TotalTicks); *)
-         SwitchScroll(ScrollLED)                             (* (iv)  *)    (* remove for student *)
-      END ;                                                                 (* remove for student *)
-      IF (TotalTicks MOD MaxQuantum) = 0                                    (* remove for student *)
-      THEN                                                                  (* remove for student *)
-         RotateRunQueue                                      (* (ii)  *)    (* remove for student *)
-      END ;                                                                 (* remove for student *)
+      INC (TotalTicks) ;                                     (* (iii) *)
+      IF EnableLED
+      THEN
+         (* now pulse scroll LED *)
+         IF (TotalTicks MOD TicksPerSecond) = 0
+         THEN
+            ScrollLED := NOT ScrollLED ;
+            (* r := printf("<scroll %d>", TotalTicks); *)
+            SwitchScroll(ScrollLED)                          (* (iv)  *)
+         END
+      END ;
+      IF (TotalTicks MOD MaxQuantum) = 0
+      THEN
+         RotateRunQueue                                      (* (ii)  *)
+      END ;
 
-      CheckActiveQueue                                       (* (i)   *)    (* remove for student *)
+      CheckActiveQueue                                       (* (i)   *)
    END
 END Timer ;
 
diff --git a/libgm2/libm2cor/KeyBoardLEDs.cc b/libgm2/libm2cor/KeyBoardLEDs.cc
index 8d2b50bf99e..32f4c0ce711 100644
--- a/libgm2/libm2cor/KeyBoardLEDs.cc
+++ b/libgm2/libm2cor/KeyBoardLEDs.cc
@@ -46,10 +46,27 @@ static int fd;
 static bool initialized = false;
 
 
+void
+initialize_module (void)
+{
+  if (! initialized)
+    {
+      initialized = true;
+      fd = open ("/dev/tty", O_RDONLY);
+      if (fd == -1)
+	{
+	  perror ("unable to open /dev/tty");
+	  exit (1);
+	}
+    }
+}
+
 extern "C" void
 EXPORT(SwitchScroll) (int scrolllock)
 {
   unsigned char leds;
+
+  initialize_module ();
   int r = ioctl (fd, KDGETLED, &leds);
   if (scrolllock)
     leds = leds | LED_SCR;
@@ -62,6 +79,8 @@ extern "C" void
 EXPORT(SwitchNum) (int numlock)
 {
   unsigned char leds;
+
+  initialize_module ();
   int r = ioctl (fd, KDGETLED, &leds);
   if (numlock)
     leds = leds | LED_NUM;
@@ -74,6 +93,8 @@ extern "C" void
 EXPORT(SwitchCaps) (int capslock)
 {
   unsigned char leds;
+
+  initialize_module ();
   int r = ioctl (fd, KDGETLED, &leds);
   if (capslock)
     leds = leds | LED_CAP;
@@ -93,16 +114,6 @@ EXPORT(SwitchLeds) (int numlock, int capslock, int scrolllock)
 extern "C" void
 M2EXPORT(init) (int, char **, char **)
 {
-  if (! initialized)
-    {
-      initialized = true;
-      fd = open ("/dev/tty", O_RDONLY);
-      if (fd == -1)
-	{
-	  perror ("unable to open /dev/tty");
-	  exit (1);
-	}
-    }
 }
 
 #else