From 9e3a65a91ed9140afc457605150ab252af4f9ab0 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Sun, 27 Dec 2015 13:06:49 +0000
Subject: [PATCH] kernel: first pieces of job control logic

---
 Kernel/include/kernel.h |  5 +++++
 Kernel/level2.c         | 20 ++++++++++++++++++++
 Kernel/tty.c            |  4 +++-
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index 54138ce3..11b352e2 100644
--- a/Kernel/include/kernel.h
+++ b/Kernel/include/kernel.h
@@ -38,6 +38,11 @@ From UZI by Doug Braun and UZI280 by Stefan Nitschke.
 
 #ifdef CONFIG_LEVEL_2
 #include "level2.h"
+#else
+
+#define jobcontrol_in(x)
+#define jobcontrol_out(x)
+
 #endif
 
 #define CPM_EMULATOR_FILENAME    "/usr/cpm/emulator"
diff --git a/Kernel/level2.c b/Kernel/level2.c
index 53bf780f..b25a5fb6 100644
--- a/Kernel/level2.c
+++ b/Kernel/level2.c
@@ -11,3 +11,23 @@ int in_group(uint16_t gid)
 			return 1;
 	return 0;
 }
+
+void jobcontrol_in(struct tty *t)
+{
+	if (udata.u_proc->p_pgrp == t->pgrp)
+		return;
+	ssig(udata.u_proc, SIGTTIN);
+	/* So we halt */
+	pause(0);
+}
+
+void jobcontrol_out(struct tty *t)
+{
+	if (udata.u_proc->p_pgrp == t->pgrp)
+		return;
+	if (!(t->termios.t_lflag & TOSTOP))
+		return;
+	ssig(udata.u_proc, SIGTTOU);
+	/* So we halt */
+	pause(0);
+}
diff --git a/Kernel/tty.c b/Kernel/tty.c
index 87bc0439..264c0c37 100644
--- a/Kernel/tty.c
+++ b/Kernel/tty.c
@@ -50,6 +50,7 @@ int tty_read(uint8_t minor, uint8_t rawflag, uint8_t flag)
 		                udata.u_error = ENXIO;
 		                return -1;
                         }
+                        jobcontrol_in(t);
 			if (remq(q, &c)) {
 				if (udata.u_sysio)
 					*udata.u_base = c;
@@ -114,8 +115,8 @@ int tty_write(uint8_t minor, uint8_t rawflag, uint8_t flag)
 				break;
 			if (psleep_flags_io(&t->flag, flag, &written))
 				return written;
+                        jobcontrol_out(t);
 		}
-
 		if (!(t->flag & TTYF_DISCARD)) {
 			if (udata.u_sysio)
 				c = *udata.u_base;
@@ -229,6 +230,7 @@ int tty_ioctl(uint8_t minor, uarg_t request, char *data)
 	        udata.u_error = ENXIO;
 	        return -1;
         }
+        jobcontrol_in(t);
 	switch (request) {
 	case TCGETS:
 		return uput(&t->termios, data, sizeof(struct termios));
-- 
2.34.1