From ef95d56394db7600023c99e8f01102c347d3433d Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Sun, 27 Dec 2015 14:02:23 +0000
Subject: [PATCH] tty: further chunks of work on the tty job control interfaces

There is a fair bit left to do, in particular all the silly signal handling
funnies BSD job control does and the signal handling special cases it causes.
---
 Kernel/include/tty.h    |  3 ++
 Kernel/level2.c         | 32 +++++++++++++++
 Kernel/syscall_level2.c | 88 +++++++++++++++++++++++++++++++++++++++++
 Kernel/tty.c            | 11 ++++++
 4 files changed, 134 insertions(+)

diff --git a/Kernel/include/tty.h b/Kernel/include/tty.h
index e557b02e..249a924b 100644
--- a/Kernel/include/tty.h
+++ b/Kernel/include/tty.h
@@ -142,6 +142,9 @@ struct termios {
 #define TIOCGWINSZ	10
 #define TIOCSWINSZ	11
 
+#define TIOCGPGRP	12
+#define TIOCSPGRP	13
+
 #define KBMAPSIZE	0x20
 #define KBMAPGET	0x21
 #define VTSIZE		0x22
diff --git a/Kernel/level2.c b/Kernel/level2.c
index b25a5fb6..1c8a1a31 100644
--- a/Kernel/level2.c
+++ b/Kernel/level2.c
@@ -16,6 +16,8 @@ void jobcontrol_in(struct tty *t)
 {
 	if (udata.u_proc->p_pgrp == t->pgrp)
 		return;
+	/* We probably want to special case a helper here because we need
+	   to handle the funnier side effects ? */
 	ssig(udata.u_proc, SIGTTIN);
 	/* So we halt */
 	pause(0);
@@ -31,3 +33,33 @@ void jobcontrol_out(struct tty *t)
 	/* So we halt */
 	pause(0);
 }
+
+int tcsetpgrp(struct tty *t, char *data)	/* data is user pointer */
+{
+	uint16_t grp = ugetw(data);
+	uint16_t ses = udata.u_ptab->p_session;
+        ptptr p;
+	uint8_t found = 0;
+
+	/* Controlling tty check is done by caller */
+
+	/* No change -> ok */
+	if (grp == tty->pgrp)
+		return 0;
+
+	for (p = ptab; p < ptab_end; ++p) {
+		/* The group exists */
+		if (p->p_pgrp == grp) {
+			/* but not within our session */
+			if (p->p_session != ses) {
+				udata.u_error = EPERM;
+				return -1;
+			}
+			/* So it's a valid group and in our session */
+			tty->pgrp = grp;
+			return 0;
+		}
+	}
+	udata.u_error = EINVAL;
+	return -1;
+}
diff --git a/Kernel/syscall_level2.c b/Kernel/syscall_level2.c
index 06b3fa3c..43a27291 100644
--- a/Kernel/syscall_level2.c
+++ b/Kernel/syscall_level2.c
@@ -111,3 +111,91 @@ bad:
 #undef res
 #undef rlim
 
+/*******************************************
+  setpgid (pid, pgid)        Function ??
+  uint16_t npid;
+  uint16_t npgid;
+ *******************************************/
+
+#define npid (uint16_t)udata.u_argn
+#define npgid (uint16_t)udata.u_argn1
+
+arg_t _setpgid(void)
+{
+	ptptr p, t;
+	uint16_t ses = udata.u_ptab->p_session;
+
+	/* pid 0 means "self" */
+	if (npid == 0)
+		t = udata.u_ptab;
+	else {
+		for (p = ptab; p < ptab_end; ++p) {
+			if (p->p_pid == npid)
+				t = p;
+		}
+	}
+	if (t == NULL) {
+		udata.u_error = ESRCH;
+		return -1;
+	}
+
+	if (t->p_session != udata.u_ptab->p_session)
+		goto invalid;
+
+	if (npgid == 0)
+		npgid = t->p_pid;
+
+	/* Check if the group is in use with a different session */
+	for (p = ptab; p < ptab_end; ++p)
+		if (p->p_pgrp == npgid && p->p_session != ses)
+			goto invalid;
+
+	t->p_pgrp = npgid;
+	return 0;
+
+invalid:
+	udata.u_error = EPERM;
+	return -1;
+}
+
+#undef npid
+#undef npgid
+
+/*******************************************
+  setsid (void)                  Function ??
+ *******************************************/
+
+arg_t _setsid(void)
+{
+	ptptr p;
+	uint16_t pid = udata.u_ptab->p_pid;
+
+	for (p = ptab; p < ptab_end; ++p) {
+		if (p->p_pgid == pid || p->p_session == pid) {
+			udata.u_error = EPERM;
+			return -1;
+		}
+	}
+	p = udata.u_ptab;
+	p->p_pgrp = pid;
+	p->p_session = pid;
+	udata.u_ctty = NULL;
+	return 0;
+}
+
+/*******************************************
+  getsid (pid)                   Function ??
+  uint16_t pid;
+ *******************************************/
+
+arg_t _getsid(void)
+{
+	ptptr p;
+	for (p = ptab; p < ptab_end; ++p) {
+		if (p->p_pid == pid)
+			return p->p_session;
+	}
+	udata.u_error = ESRCH;
+	return -1;
+}
+
diff --git a/Kernel/tty.c b/Kernel/tty.c
index 264c0c37..4dc68334 100644
--- a/Kernel/tty.c
+++ b/Kernel/tty.c
@@ -267,6 +267,17 @@ int tty_ioctl(uint8_t minor, uarg_t request, char *data)
                         return -1;
                 sgrpsig(t->pgrp, SIGWINCH);
                 return 0;
+        case TIOCGPGRP:
+                return uputw(t->pgrp, data);
+#ifdef CONFIG_LEVEL_2
+        case TIOCSPGRP:
+                /* Only applicable via controlling terminal */
+                if (minor != udata.u_ptab->p_tty) {
+                        udata.u_error = ENOTTY;
+                        return -1;
+                }
+                return tcsetpgrp(minor, t, data);
+#endif
 	default:
 		udata.u_error = ENOTTY;
 		return -1;
-- 
2.34.1