X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/0b4c1975fb5e4eccf1012a35081f7e7799b81046..c18c124eaa464aaaa5549e99e5a70fc9cbb50944:/bsd/kern/tty.c

diff --git a/bsd/kern/tty.c b/bsd/kern/tty.c
index 841781612..2586c482f 100644
--- a/bsd/kern/tty.c
+++ b/bsd/kern/tty.c
@@ -130,7 +130,7 @@ static lck_grp_t	*tty_lck_grp;
 static lck_grp_attr_t	*tty_lck_grp_attr;
 static lck_attr_t      *tty_lck_attr;
 
-static int	ttnread(struct tty *tp);
+__private_extern__ int ttnread(struct tty *tp);
 static void	ttyecho(int c, struct tty *tp);
 static int	ttyoutput(int c, struct tty *tp);
 static void	ttypend(struct tty *tp);
@@ -142,6 +142,9 @@ static void	ttyunblock(struct tty *tp);
 static int	ttywflush(struct tty *tp);
 static int	proc_compare(proc_t p1, proc_t p2);
 
+static void	ttyhold(struct tty *tp);
+static void	ttydeallocate(struct tty *tp);
+
 static int isctty(proc_t p, struct tty  *tp);
 static int isctty_sp(proc_t p, struct tty  *tp, struct session *sessp);
 
@@ -339,8 +342,9 @@ int
 ttyopen(dev_t device, struct tty *tp)
 {
 	proc_t p = current_proc();
-	struct pgrp * pg, * oldpg;
+	struct pgrp *pg, *oldpg;
 	struct session *sessp, *oldsess;
+	struct tty *oldtp;
 
 	TTY_LOCK_OWNED(tp);	/* debug assert */
 
@@ -359,15 +363,15 @@ ttyopen(dev_t device, struct tty *tp)
 	/*
 	 * First tty open affter setsid() call makes this tty its controlling
 	 * tty, if the tty does not already have a session associated with it.
-	 * Only do this if the process
 	 */
-	if (SESS_LEADER(p, sessp) &&			/* process is session leader */
+	if (SESS_LEADER(p, sessp) &&	/* the process is the session leader */
 	    sessp->s_ttyvp == NULL &&	/* but has no controlling tty */
-	    tp->t_session == NULL ) {		/* and tty not controlling */
+	    tp->t_session == NULL ) {	/* and tty not controlling */
 		session_lock(sessp);
 	    	if ((sessp->s_flags & S_NOCTTY) == 0) {	/* and no O_NOCTTY */
-			/* Hold on to the reference */
-			sessp->s_ttyp = tp;	/* XXX NOT A REFERENCE */
+			oldtp = sessp->s_ttyp;
+			ttyhold(tp);
+			sessp->s_ttyp = tp;
 			OSBitOrAtomic(P_CONTROLT, &p->p_flag);
 			session_unlock(sessp);
 			proc_list_lock();
@@ -385,6 +389,8 @@ ttyopen(dev_t device, struct tty *tp)
 				pg_rele(oldpg);
 			if (oldsess != SESSION_NULL)
 				session_rele(oldsess);	
+			if (NULL != oldtp)
+				ttyfree(oldtp);
 			tty_lock(tp);
 			goto out;
 	     	}
@@ -954,6 +960,29 @@ ttyoutput(int c, struct tty *tp)
 	return (-1);
 }
 
+/*
+ * Sets the tty state to not allow any more changes of foreground process
+ * group. This is required to be done so that a subsequent revoke on a vnode
+ * is able to always successfully complete.
+ *
+ * Locks :   Assumes tty_lock held on entry
+ */
+void
+ttysetpgrphup(struct tty *tp)
+{
+	TTY_LOCK_OWNED(tp);     /* debug assert */
+	SET(tp->t_state, TS_PGRPHUP);
+}
+
+/*
+ * Locks : Assumes tty lock held on entry
+ */
+void
+ttyclrpgrphup(struct tty *tp)
+{
+	TTY_LOCK_OWNED(tp);     /* debug assert */
+	CLR(tp->t_state, TS_PGRPHUP);
+}
 
 /*
  * ttioctl
@@ -1047,8 +1076,9 @@ ttioctl_locked(struct tty *tp, u_long cmd, caddr_t data, int flag, proc_t p)
 {
 	int error = 0;
 	struct uthread *ut;
-	struct pgrp * pg, *oldpg;
-	struct session *sessp, * oldsessp;
+	struct pgrp *pg, *oldpg;
+	struct session *sessp, *oldsessp;
+	struct tty *oldtp;
 
 	TTY_LOCK_OWNED(tp);	/* debug assert */
 
@@ -1404,7 +1434,9 @@ ttioctl_locked(struct tty *tp, u_long cmd, caddr_t data, int flag, proc_t p)
 		tp->t_pgrp = pg;
 		proc_list_unlock();
 		session_lock(sessp);
-		sessp->s_ttyp = tp;	/* XXX NOT A REFERENCE */
+		oldtp = sessp->s_ttyp;
+		ttyhold(tp);
+		sessp->s_ttyp = tp;
 		session_unlock(sessp);
 		OSBitOrAtomic(P_CONTROLT, &p->p_flag);
 		/* SAFE: All callers drop the lock on return */
@@ -1414,6 +1446,8 @@ ttioctl_locked(struct tty *tp, u_long cmd, caddr_t data, int flag, proc_t p)
 			session_rele(oldsessp);
 		if (oldpg != PGRP_NULL)
 			pg_rele(oldpg);
+		if (NULL != oldtp)
+			ttyfree(oldtp);
 		tty_lock(tp);
 		break;
 
@@ -1442,6 +1476,15 @@ ttioctl_locked(struct tty *tp, u_long cmd, caddr_t data, int flag, proc_t p)
 			error = EPERM;
 			goto out;
 		}
+		/*
+		 * The session leader is going away and is possibly going to revoke
+		 * the terminal, we can't change the process group when that is the
+		 * case.
+		 */
+		if (ISSET(tp->t_state, TS_PGRPHUP)) {
+			error = EPERM;
+			goto out;
+		}
 		proc_list_lock();
 		oldpg = tp->t_pgrp;
 		tp->t_pgrp = pgrp;
@@ -1498,6 +1541,8 @@ out:
 int
 ttyselect(struct tty *tp, int rw, void *wql, proc_t p)
 {
+	int retval = 0;
+
 	if (tp == NULL)
 		return (ENXIO);
 
@@ -1505,20 +1550,32 @@ ttyselect(struct tty *tp, int rw, void *wql, proc_t p)
 
 	switch (rw) {
 	case FREAD:
-		if (ttnread(tp) > 0 || ISSET(tp->t_state, TS_ZOMBIE))
+		if (ISSET(tp->t_state, TS_ZOMBIE)) {
 			return(1);
+		}
+
+		retval = ttnread(tp);
+		if (retval > 0) {
+			break;
+		}
+
 		selrecord(p, &tp->t_rsel, wql);
 		break;
 	case FWRITE:
-		if ((tp->t_outq.c_cc <= tp->t_lowat &&
-		     ISSET(tp->t_state, TS_CONNECTED))
-		    || ISSET(tp->t_state, TS_ZOMBIE)) {
-			return (1);
+		if (ISSET(tp->t_state, TS_ZOMBIE)) {
+			return(1);
+		}
+
+		if ((tp->t_outq.c_cc <= tp->t_lowat) &&
+				ISSET(tp->t_state, TS_CONNECTED)) {
+			retval = tp->t_hiwat - tp->t_outq.c_cc;
+			break;
 		}
+
 		selrecord(p, &tp->t_wsel, wql);
 		break;
 	}
-	return (0);
+	return retval;
 }
 
 
@@ -1545,7 +1602,7 @@ ttselect(dev_t dev, int rw, void *wql, proc_t p)
 /*
  * Locks:	Assumes tp is locked on entry, remains locked on exit
  */
-static int
+__private_extern__ int
 ttnread(struct tty *tp)
 {
 	int nread;
@@ -2120,7 +2177,7 @@ read:
 		char ibuf[IBUFSIZ];
 		int icc;
 
-		icc = min(uio_resid(uio), IBUFSIZ);
+		icc = MIN(uio_resid(uio), IBUFSIZ);
 		icc = q_to_b(qp, (u_char *)ibuf, icc);
 		if (icc <= 0) {
 			if (first)
@@ -2161,8 +2218,8 @@ slowcase:
 			tty_pgsignal(tp, SIGTSTP, 1);
 			tty_lock(tp);
 			if (first) {
-				error = ttysleep(tp, &lbolt, TTIPRI | PCATCH,
-						 "ttybg3", 0);
+				error = ttysleep(tp, &ttread, TTIPRI | PCATCH,
+						 "ttybg3", hz);
 				if (error)
 					break;
 				goto loop;
@@ -2341,7 +2398,7 @@ loop:
 		 * leftover from last time.
 		 */
 		if (cc == 0) {
-			cc = min(uio_resid(uio), OBUFSIZ);
+			cc = MIN(uio_resid(uio), OBUFSIZ);
 			cp = obuf;
 			error = uiomove(cp, cc, uio);
 			if (error) {
@@ -3024,22 +3081,57 @@ ttymalloc(void)
 		lck_mtx_init(&tp->t_lock, tty_lck_grp, tty_lck_attr);
 		klist_init(&tp->t_rsel.si_note);
 		klist_init(&tp->t_wsel.si_note);
+		tp->t_refcnt = 1;
 	}
-	return(tp);
+	return (tp);
 }
 
+/*
+ * Increment the reference count on a tty.
+ */
+static void
+ttyhold(struct tty *tp)
+{
+	TTY_LOCK_OWNED(tp);
+	tp->t_refcnt++;
+}
 
 /*
- * Free a tty structure and its buffers.
- *
- * Locks:	The tty_lock() is assumed to not be held at the time of
- *		the free; this functions destroys the mutex.
+ * Drops a reference count on a tty structure; if the reference count reaches
+ * zero, then also frees the structure and associated buffers.
  */
 void
 ttyfree(struct tty *tp)
+{
+	TTY_LOCK_NOTOWNED(tp);
+
+	tty_lock(tp);
+	if (--tp->t_refcnt == 0) {
+		tty_unlock(tp);
+		ttydeallocate(tp);
+	} else if (tp->t_refcnt < 0) {
+		panic("%s: freeing free tty %p", __func__, tp);
+	} else
+		tty_unlock(tp);
+}
+
+/*
+ * Deallocate a tty structure and its buffers.
+ *
+ * Locks:	The tty_lock() is assumed to not be held at the time of
+ *		the free; this function destroys the mutex.
+ */
+static void
+ttydeallocate(struct tty *tp)
 {
 	TTY_LOCK_NOTOWNED(tp);	/* debug assert */
 
+#if DEBUG
+	if (!(SLIST_EMPTY(&tp->t_rsel.si_note) && SLIST_EMPTY(&tp->t_wsel.si_note))) {
+		panic("knotes hooked into a tty when the tty is freed.\n");
+	}
+#endif /* DEBUG */
+
 	clfree(&tp->t_rawq);
 	clfree(&tp->t_canq);
 	clfree(&tp->t_outq);
@@ -3077,4 +3169,3 @@ isctty_sp(proc_t p, struct tty  *tp, struct session *sessp)
 	return(sessp == tp->t_session && p->p_flag & P_CONTROLT);
 
 }
-